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PubMed2006

Spray pattern analysis for metered dose inhalers I: Orifice size, particle size, and droplet motion correlations.

Factors that influence spray pattern measurements of pressurized, metered-dose inhalers have been evaluated. Spray patterns were correlated with changes in actuator orifice diameter, particle size profiles, and calculated estimates of particle-size dynamics of plumes during a spray. Spray patterns, regardless of actuator orifice size, were ellipsoid in the vertical direction. Measures of elliptical ratio, major axis, and minor axis were significantly influenced by orifice size in a non-linear fashion over the range of orifice sizes investigated. Spray patterns also correlated with particle size profile and spray geometry measurements. Spray distribution asymmetry may be related to droplet evaporation and sedimentation processes. However, the spray patterns did not appear sensitive to changes in gravitational force acting on the plume. Instead, it is postulated that elliptical spray patterns may have dependence on fluid dynamic processes within the inhaler actuator. Developing an understanding of these processes may provide a basis for developing spray pattern tests with relevance to product performance.

Aerosol Propellants↗
PubMed2006

Asymptotic size determines species abundance in the marine size spectrum.

The majority of higher organisms in the marine environment display indeterminate growth; that is, they continue to grow throughout their life, limited by an asymptotic size. We derive the abundance of species as a function of their asymptotic size. The derivation is based on size-spectrum theory, where population structure is derived from physiology and simple arguments regarding the predator-prey interaction. Using a hypothesis of constant satiation, which states that the average degree of satiation is independent of the size of an organism, the number of individuals with a given size is found to be proportional to the weight raised to the power -2.05, independent of the predator/prey size ratio. This is the first time the spectrum exponent has been derived solely on the basis of processes at the individual level. The theory furthermore predicts that the parameters in the von Bertalanffy growth function are related as K ∝ L⁻¹∞

Animals↗
PubMed2003

Gene genealogies when the sample size exceeds the effective size of the population.

We study the properties of gene genealogies for large samples using a continuous approximation introduced by R. A. Fisher. We show that the major effect of large sample size, relative to the effective size of the population, is to increase the proportion of polymorphisms at which the mutant type is found in a single copy in the sample. We derive analytical expressions for the expected number of these singleton polymorphisms and for the total number of polymorphic, or segregating, sites that are valid even when the sample size is much greater than the effective size of the population. We use simulations to assess the accuracy of these predictions and to investigate other aspects of large-sample genealogies. Lastly, we apply our results to some data from Pacific oysters sampled from British Columbia. This illustrates that, when large samples are available, it is possible to estimate the mutation rate and the effective population size separately, in contrast to the case of small samples in which only the product of the mutation rate and the effective population size can be estimated.

DNA, Mitochondrial↗
PubMed2002

A bird's-eye view of the C-value enigma: genome size, cell size, and metabolic rate in the class aves.

For half a century, variation in genome size (C-value) has been an unresolved puzzle in evolutionary biology. While the initial "C-value paradox" was solved with the discovery of noncoding DNA, a much more complex "C-value enigma" remains. The present study focuses on one aspect of this puzzle, namely the small genome sizes of birds. Significant negative correlations are reported between resting metabolic rate and both C-value and erythrocyte size. Cell size is positively correlated with both nucleus size and C-value in birds, as in other vertebrates. These findings shed light on the constraints acting on genome size in birds and illustrate the importance of interactions among various levels of the biological hierarchy, ranging from the subchromosomal to the ecological. Following from a discussion of the mechanistic bases of the correlations reported and the processes by which birds achieved and/or maintain small genomes, a pluralistic approach to the C-value enigma is recommended.

Animals↗
PubMed2003

Different cell size and cell number contribution in two newly established and one ancient body size cline of Drosophila subobscura.

Latitudinal genetic clines in body size occur in many ectotherms including Drosophila species. In the wing of D. melanogaster, these clines are generally based on latitudinal variation in cell number. In contrast, differences in wing area that evolve by thermal selection in the laboratory are in general based on cell size. To investigate possible reasons for the different cellular bases of these two types of evolutionary response, we compared the newly established North and South American wing size clines of Drosophila subobscura. The new clines are based on latitudinal variation in cell area in North America and cell number in South America. The ancestral European cline is also based on latitudinal variation in cell number. The difference in the cellular basis of wing size variation in the American clines, which are roughly the same age, together with the similar cellular basis of the new South American cline and the ancient European one, suggest that the antiquity of a cline does not explain its cellular basis. Furthermore, the results indicate that wing size as a whole, rather than its cellular basis, is under selection. The different cellular bases of different size clines are most likely explained either entirely by chance or by different patterns of genetic variance--or its expression--in founding populations.

Animals↗
PubMed2006

Cope's rule in cryptodiran turtles: do the body sizes of extant species reflect a trend of phyletic size increase?

Cope's rule of phyletic size increase is questioned as a general pattern of body size evolution. Most studies of Cope's rule have examined trends in the paleontological record. However, neontological approaches are now possible due to the development of model-based comparative methods, as well as the availability of an abundance of phylogenetic data. I examined whether the phylogenetic distribution of body sizes in extant cryptodiran turtles is consistent with Cope's rule. To do this, I examined body size evolution in each of six major clades of cryptodiran turtles and also across the whole tree of cryptodirans (n = 201 taxa). Extant cryptodiran turtles do not appear to follow Cope's rule, as no clade showed a significant phyletic body size trend. Previous analyses in other extant vertebrates have also found no evidence for phyletic size increase, which is in contrast to the paleontological data that support the rule in a number of extinct vertebrate taxa.

Animals↗
PubMed1989

Event-related potentials during memory search and selective attention to letter size and conjunctions of letter size and color.

The analysis of event-related potentials was used in two experiments to investigate the structure of information processing in a task in which subjects selectively attended to letter size (Experiment 1) or a conjunction of letter size and color (Experiment 2) and searched for target letters within the attended stimulus category. The event-related potentials showed that selective attention to letter size resulted in the enhancement of a central N2b component (onset about 200 ms), which was assumed to reflect feature nonspecific orienting of attention. When attention was directed to conjunctions of letter size and color an earlier effect was found (onset about 150 ms) consisting of positivity at the anterior electrodes and negativity at OZ. This earlier effect was assumed to reflect feature-specific selective processing. Although the early effect showed a hierarchical pattern of results, in which the effect of attending to size was contingent on the relevance of the color attribute, the N2b showed a more independent pattern of results, in which the relevance of either the color or the size attribute resulted in an enhancement of this component, independent of the relevance of the other attribute. An increase in the duration of the memory search process resulted in a prolonged negativity with an onset of about 200 ms which was maximal at CZ. In both experiments the initial phase of this negativity was also found in the event-related potentials to the unattended stimulus categories, suggesting that the search process was initiated nonselectively and terminated after the selection cues were identified. Detection of attended target letters resulted in a parietal P3b component. In both experiments there was an earlier effect discriminating targets and nontargets in the range 200-300 ms.

Adult↗
PubMed2004

Males have larger skeletal size and bone mass than females, despite comparable body size.

UNLABELLED: Gender differences in fractures may be related to body size, bone size, geometry, or density. We studied this in 18-year-old males (n = 36) and females (n = 36) matched for height and weight. Despite comparable body size, males have greater BMC and BMD at the hip and distal tibia and greater tibial cortical thickness. This may confer greater skeletal integrity in males. INTRODUCTION: Gender differences in fractures may be related to body size, bone size, geometry, or density. We studied this in males (n = 36) and females (n = 36; mean age = 18 years) pair-matched for height and weight. MATERIALS AND METHODS: BMC, bone area (BA), and BMD were measured in the spine and hip using DXA. Distal tibia was measured by pQCT. RESULTS AND CONCLUSIONS: Males had a higher lean mass (92%) compared with females (79%). No gender differences were observed for vertebral BMC or vertebral height, although males had greater width and thus BA at the spine. Males had greater BMC and BA at the femoral neck and total femur (p < 0.02). Geometric variables of the hip including neck diameter and neck-axis length were also greater in males (p < 0.02). There was greater cross-sectional moment of inertia, safety factor, and fall index in males (all p < 0.02). Males had greater tibial BMC, volumetric BMD, and cortical area and thickness compared with females (p < 0.01), with both greater periosteal circumference (p = 0.011) and smaller endosteal circumference (p = 0.058). Statistically controlling for lean mass reduced gender differences, but males still had 8% higher hip BMD (p = 0.24) and 5.3% higher total tibial BMD (p = 0.05). A subset of males and females were matched (n = 14 pairs) for total hip BA. Males in this subset still had greater BMC and BMD at the total hip (p < 0.05) than females, despite similar BA. In summary, despite comparable body size, males have greater BMC and BMD than females at the hip and distal tibia but not at the spine. Differences in BMC and BMD were related to greater cortical thickness in the tibia. We conclude that differences in bone mass and geometry confer greater skeletal integrity in males, which may contribute to the lower incidence of stress and osteoporotic fractures in males.

Adolescent↗
PubMed1979

Effect of familiar size on judgments of relative size and distance.

Carlson and Tassone (1971) found that for far viewing distances a person was judged taller in objective size, smaller in apparent size, and more distant than a board of the same size and at the same distance as the person. The purpose of this experiment was to replicate Carlson and Tassone's findings for near viewing distances. Subjects compared to size and distance of familiar and unfamiliar objects viewed from a distance of 5.3 m. The two objects were judged equal in both apparent and objective size and the familiar object was judged as more distant than the unfamiliar object. It is suggested that the distance results can best be explained in terms of the detail pattern cue rather than the familiar size cue to relative distance.

Adolescent↗
PubMed2004

"Small-for-size graft" and "small-for-size syndrome" in living donor liver transplantation.

The indications for living donor liver transplantation (LDLT) were successfully expanded from pediatric to adult cases last 15 years. During this process, graft type has been shifted from left side liver to right side liver. Although the introduction of right lobe graft can successfully increase the actual graft size in LDLT, problem related to "small-for-size grafts" have gradually come to light. "Small-for-size syndrome", such as poor bile production, delayed synthetic function, prolonged cholestasis, and intractable ascites, leading to septic complications and higher mortality, are neither specific nor inevitable in low-weight liver grafts. Many factors other than actual graft weight contribute to the occurrence of "small- for-size syndrome". In the clinical setting, surgical modification targeting portal hemodynamics and tissue congestion is a key to overcome "small-for-size syndrome". Until now, several therapeutic options were reported, but further elucidation of the pathogenesis in "small-for-size syndrome" will be a solution for improving the outcomes in adult-to-adult LDLT.

Humans↗
PubMed2006

Meal size, not body size, explains errors in estimating the calorie content of meals.

BACKGROUND: Although most people underestimate the calories they consume during a meal or during the day, calorie underestimation is especially extreme among overweight persons. The reason for this systematic bias is unknown. OBJECTIVE: To investigate whether the association between calorie underestimation and body mass reflects a tendency for all persons to underestimate calories as the size of a meal increases. DESIGN: Overweight and normal-weight adults estimated the number of calories of a fast-food meal they had ordered and eaten (study 1) or of 15 fast-food meals that were chosen by the experimenter (study 2) in a randomized, controlled trial. Their estimations were compared with the actual number of calories of the meals. SETTING: Study 1 was a field study conducted in fast-food restaurants in 3 medium-sized midwestern U.S. cities. Study 2 was conducted in a laboratory at a major U.S. research university. PARTICIPANTS: Study 1 involved 105 lunchtime diners (average body mass index [BMI], 24.2 kg/m2 [range, 17.2 to 33.5 kg/m2]). Study 2 involved 40 undergraduate students (average BMI, 23.2 kg/m2 [range, 16.1 to 32.3 kg/m2]). MEASUREMENTS: Participants were asked to estimate the number of calories in a fast-food meal they had ordered and eaten (study 1) or in 15 sizes of the same fast-food meal (study 2). The actual number of calories in the meals in the field study was obtained by unobtrusively recording the food that was ordered (identified from the wrappings and containers). Weight and height were self-reported. RESULTS: Although participants strongly underestimated the number of calories in larger meals (by -38.0% in study 1 and by -22.6% in study 2), they almost perfectly estimated the number of calories in smaller meals (by -2.9% in study 1 and by 3.0% in study 2). After the authors controlled for body weight-related differences in meal size, the calorie estimations of normal-weight and overweight participants were identical in both studies. LIMITATIONS: These studies examined fast-food meals. Weight and height were self-reported. There were too few observations to distinguish between obese (BMI > or =30 kg/m2) and overweight (BMI >25 kg/m2 but <30 kg/m2) participants. CONCLUSIONS: Greater underestimation of calories by overweight persons is a consequence of their tendency to consume larger meals. Calorie underestimation is related to meal size, not body size.

Adult↗
PubMed2002

[Study of molecular genetics of the size of reproductive organs and litter size in the sow].

The mutations of ESR, PRLR and FSHR genes were investigated by SNP; 103 F2 sows were slaughtered and their reproductive organs were determined; the litter size of sow was recorded. The linkage between mutations of genes and size of reproductive organ, litter size was analyzed. The results revealed: these sows that could provide more piglets with bigger reproductive organs usually carried genotype like as genotype BB on the sites of ESR, FSHRB and the genotype AA on the sites of ESRB and PRLR, that is, the genotype of BB on the sites of ESR or FSHRB in sow was not only helpful to promote growth of reproductive organs, but also benefit to improve litter size; The size of productive organs and litter size of the sow with genotype AA on the sites of ESRB or PRLR were significantly higher than those of sow with genotype AB or BB.

Animals↗
PubMedDate not supplied

The size distribution of thyroid follicles in single thyroid glands, a peculiar problem of particle size distribution in stereology.

Follicle sections vary in size according to their inclination mainly in hypertrophied thyroids. Sagittal sections elicit a shift to small classes, while transversal sections, to large classes. There is no mathematical transformation able to convert data obtained by sections into "true" sizes of follicles, as may be achieved by isolation. All papers emphasizing only section diameters and inferring about follicle size must be cautiously interpreted, and even discarded, if they tend to establish differences in follicle size solely on that basis. Follicle isolation is necessary if we need to establish follicle size and shape. Although proportions are almost stable for rats of the same age and weight, the proportions of follicle size may vary, as dependent on age and other internal and external conditions. The situation is most complicated by colloid accumulation; but despite these impedimenta, TSH secretion enlarges the follicles, a situation hitherto not well established. Cell enlargement is consequently followed by follicle enlargement, despite colloid resorption.

Animals↗
PubMed1989

The discrepancy between emotional vs. rational estimates of body size, actual size, and ideal body ratings: theoretical and clinical implications.

Thirty-two asymptomatic college females were assessed on multiple aspects of body image. Subjects' estimation of the size of three body sites (waist, hips, thighs) was affected by instructional protocol. Emotional ratings, based on how they "felt" about their body, elicited ratings that were larger than actual and ideal size measures. Size ratings based on rational instructions were no different from actual sizes, but were larger than ideal ratings. There were no differences between actual and ideal sizes. The results are discussed with regard to methodological issues involved in body image research. In addition, a working hypothesis that differentiates affective/emotional from cognitive/rational aspects of body size estimation is offered to complement current theories of body image. Implications of the findings for the understanding of body image and its relationship to eating disorders are discussed.

Adolescent↗
PubMed1995

Size-selected genomic libraries: the distribution and size-fractionation of restricted genomic DNA fragments by gel electrophoresis.

By using one-dimensional genome scanning, it is possible to directly identify the restricted genomic DNA fragment that reflects the site of genetic change. The subsequent strategies to obtain the molecular clones of the corresponding restriction fragment are usually as follows: (i) the restriction of a mass quantity of an appropriate genomic DNA, (ii) the size-fractionation of the restricted DNA on a preparative electrophoresis gel in order to enrich the corresponding restriction fragment, (iii) the construction of the size-selected libraries from the fractionated genomic DNA, and (iv) the screening of the library to obtain an objective clone which is identified on the analytical genome scanning gel. A knowledge of the size distribution pattern of restriction fragments of the genomic DNA makes it possible to calculate the heterogeneity or complexity of the restriction fragment in each size-fraction. This manuscript first describes the distribution of the restriction fragments with respect to their length. Some examples of the practical application of this theory to genome scanning is then discussed using presumptive genome scanning gels. The way to calculate such DNA complexities in the prepared size-fractionated samples is also demonstrated. Such information should greatly facilitate the design of experimental strategies for the cloning of a certain size of genomic DNA after digestion with restriction enzyme(s) as is the case with genome scanning.

Animals↗
PubMed2005

Size fractionation of marine sediments by pinched inlet gravitational split-flow thin fractionation and the study of size dependent PCDD/Fs concentrations from different bay areas.

Pinched inlet gravitational split-flow thin fractionation (PI-GSF) has been applied to the continuous size fractionation of marine sediments in order to study the difference in sediment size distribution and the concentration of PCDD/Fs contained in different particle sizes. A PI-GSF channel, known to improve the separation efficiency by reducing the sample inlet thickness, was utilized to fractionate sediments collected from three different bay areas (Geoje, Ulsan, and Pohang) in Korea into 5 different sub-populations (<2.0, 2.0-5.0, 5.0-10, 10-20, 20-63 microm in diameter). The sorted sediment fractions from PI-GSF were examined using electron microscopy to obtain size distribution and the results showed a variation in particle size distribution between bay areas. When the collected particle fractions were examined for size dependent levels of PCDD/Fs, the concentrations of total PCDD/Fs were shown to be much greater for samples collected close to heavy industry complexes than sediments from bay areas without major industry.

Journal Article↗
PubMed2001

Balanced-size and long-size cloning of full-length, cap-trapped cDNAs into vectors of the novel lambda-FLC family allows enhanced gene discovery rate and functional analysis.

We have developed a new class of cloning vectors: lambda-full-length cDNA (lambda-FLC) cloning vectors. These vectors can be bulk-excised for preparing full-length cDNA libraries in which a high proportion of the plasmids carry large inserts that can be transferred into other (for example, functional) vectors. Unlike other cloning vectors, lambda-FLC vectors accommodate a broad range of sizes of eukaryotic cDNA inserts because they contain "size balancers." Further, the main protocol we use for direct bulk excision of plasmids is mediated by a Cre-lox system and is apparently free of size bias. The average size of the inserts from excised plasmid cDNA libraries was 2.9 kb for standard and 6.9 kb for size-selected cDNA. The average insert size of the full-length cDNA libraries was correlated to the rate of new gene discovery, suggesting that effectively cloning rarely expressed mRNAs requires vectors that can accommodate large inserts from a variety of sources. Part of the vectors are also suitable for bulk transfer of inserts into various functional vectors.

Animals↗