Role Of Size Research Articles

Nanoparticle heterodimers: The role of size and interparticle gap distance on the optical response

Composite plasmonic nanostructures with controlled size, shape and relative arrangement is a subject of significant current research interest. Much of this is stimulated by the prospects by generating enormous near-field enhancements of the surface and interparticle gap regions for potential applications in surface-enhanced spectroscopies. In this manuscript, using time-dependent density functional theory (TDDFT) calculations, we investigate how the optical response in size matched homodimers and size mismatched heterodimers composed of Aluminum modify while varying the size and interparticle gap distances in the sub-nanometer range. Both systems show interesting optical response evolution. In particular, the size mismatched heterodimers show even more complex optical response evolution due to a symmetry-breaking in the system.

Innovation in small-scale aquaculture in Chile

ABSTRACTIn light of the current depletion of extractive marine resources and the sustainability issues that have arisen in the aquaculture industry, the small-scale aquaculture sector has emerged as a viable and sustainable alternative for generating income. To integrate the small-scale aquaculture sector into the food value chain, understanding the decision-making process to innovate becomes essential. This paper explores the factors underlying both innovation choices and intensity among small-scale aquaculture producers by utilizing exclusive census data from the small-scale aquaculture sector in Chile. The results indicate that education, secure property rights, internet access, participation in organizations, commercialization methods, government instruments, understanding of credit, and social learning promote innovation decisions. We also find that largest producers innovate in more areas, suggesting a role of size for both technological and non-technological innovations.

Diagnostic yield of EUS-FNA of small (≤15 mm) solid pancreatic lesions using a 25-gauge needle

BackgroundEarly detection of small solid pancreatic lesions is increasingly common. To date, few and contradictory data have been published about the relationship between lesion size and endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) diagnostic yield. The aim of this study was to assess the relation between the size of solid pancreatic lesions and the diagnostic yield of EUS-FNA using a 25-gauge needle in a center without available rapid on-site evaluation. MethodsIn the retrospective cohort study, we selected patients who underwent EUS-FNA for solid pancreatic lesions with a 25-gauge needle from October 2014 to October 2015. Patients were divided into three groups (≤15 mm, 16–25 mm and >25 mm), and the outcomes were compared. ResultsWe analyzed 163 patients. Overall adequacy, sensitivity, specificity and accuracy were 85.2%, 81.8%, 93.7%, and 80.4%, respectively. When stratified by size, the sensitivity and accuracy correlated with size (P = 0.016 and P = 0.042, respectively). Multivariate analysis showed that lesion size was the only independent factor (P = 0.019, OR = 4.76) affecting accuracy. The role of size as an independent factor affecting accuracy was confirmed in a separate multivariate analysis, where size was included in the model as a covariate (P = 0.018, OR = 1.08). ConclusionOur study demonstrates that, in the absence of rapid on-site evaluation, mass size affects the accuracy of EUS-FNA of solid pancreatic lesions.

Profitability, Earnings Per Share on Stock Return with Size as Moderation

The purpose of this study was to analyze the effect of profitability and earnings per share on stock returns and the role of size as a moderating variable in state-owned companies listed in the Indonesia Stock Exchange (IDX) in the period of 2011-2016. By using purposive sampling, the number of samples included 18 companies. Method was conducted by downloading summary of financial statements in the Indonesia Stock Exchange. The research began with classical assumption test, multiple linear regression analysis was done with the absolute difference test. The research found that profitability had no effect on stock return. Earnings per share and size had a significant negative effect on stock return. The role of size as a moderating variable strengthened the relationship of earnings per share with stock returns, but it did not play a role in the relationship of profitability with stock returns.

Vanishing Pancreatic Cysts during Follow-Up: Another Step Towards De-Emphasizing Cyst Size as a Major Clinical Predictor of Malignancy

Introduction: In the management of pancreatic cystic neoplasms (PCN), size plays a crucial role as the expression of disease progression. While many evidences regarding the natural history of growing pancreatic cysts exist, almost no data are available regarding cysts with a reduction in size. Methods: Radiological and clinical data from patients of the dedicated pancreatic cysts outpatient clinic of the Department of General and Pancreatic Surgery, University of Verona Hospital were retrospectively reviewed. Patients diagnosed with PCNs reducing in size during follow-up were reviewed. Results: From a total of 3,146 patients, we identified 12 (0.38%) vanishing/reducing cysts without a history of pancreatitis. Most of them were presumed IPMN (66.6%). The median follow-up was 69 months and the median cyst’s size 30 mm (range 10–49). Most of the patients (75%) experienced a reduction in cyst size (median reduction of 8 mm, range 6–22) after a median time of 12 months (range 6–63), 3 patients experienced a complete disappearance of the cyst. Conclusion: Cyst size reduction during follow-up is a rare phenomenon of unknown explanation. It adds to the debate regarding the role of size as a clinical predictor whenever a definite diagnosis of a PCN cannot be reached.

The Peer Group in European Market Multiples: The Problem of Size

The aim of this paper is to bring a new perspective to the role of control factors in MARKET-EBITDA, MARKET-SALES and MARKET-BOOK ratios in the European market, which are different from industry. We analyze the role of size and its interactions with the rest of the variables: profitability, risk, and structural asset factors. For this purpose, we have developed a valuation model using panel data methodology for listed European firms from the period 2002-2013. We found that size includes economic aspects of the companies, but also differential investors’ perceptions about these economic aspects. It makes it a complementary explanation factor on the selection of the peer group with the rest of the variables. These findings help to understand the variation of market ratios and share prices depending on size in different economic conditions or economic cycles. This research is in accordance with the theoretical framework of market ratios and with size effect theory.

Role of size on the relative importance of fluid dynamic losses in linear cryocoolers

Thermodynamic modeling results for a novel small satellite (SmallSat) Stirling Cryocooler, capable of delivering over 200 mW net cooling power at 80 K for less than 6 W DC input power, are used in this paper as the basis for related pulse tube computational fluid dynamics (CFD) analysis. Industry and government requirements for SmallSat infrared sensors are driving the development of ever-more miniaturized cryocooler systems. Such cryocoolers must be extremely compact and lightweight, a challenge met by this research team through operating a Stirling cryocooler at a frequency of approximately 300 Hz. The primary advantage of operating at such a high frequency is that the required compression and expansion swept volumes are reduced relative to linear coolers operating at lower frequencies, which evidently reduces the size of the motor mechanisms and the thermodynamic components. In the case of a pulse tube cryocooler, this includes a reduction in diameter of the pulse tube itself. This unfortunately leads to high boundary layer losses, as the presented results demonstrate. Using a Stirling approach with a mechanical moving expander piston eliminates this small pulse tube loss mechanism, but other challenges are introduced, such as maintaining very tight clearance gaps between moving and stationary elements. This paper focuses on CFD modelling results for a highly miniaturized pulse tube cooler.

Roles of size and kinematics in drag reduction for two tandem flexible foils

The effect of size and kinematics difference between two tandem flexible foils on drag reduction have been numerically studied. Compared with single foil, it is found that the kinematics difference between two foils would not play a significant role in reducing drag, while the size difference between two foils significantly affects the drag reduction in this two foil system. For leading foil, it always enjoys drag reduction and the highest drag reduction can be observed at bigger size difference and gap distance between two foil as 22%. For trailing foil, it suffers drag increase when the gap distance between two foils is smaller, while it enjoys drag decrease when the size difference between two foils is bigger enough. The hydrodynamic interaction between such actively undulated foils also has been uncovered and used to explain the mechanisms of drag reduction.

Early time course of variation in coelomic fluid ionic concentrations in sea urchins abruptly exposed to hypo- and hyper-osmotic salinity challenges: Role of size and cross-section area of test holes.

Echinoderms are restricted to the marine environment and are osmoconformer invertebrates. However, some species live in unstable environments. Especially those species, and those of larger body size, tend to show variable, albeit transient, ionic gradients between their coelomic fluid and external seawater. In order to further examine how sea urchin size relates to apparent ionic permeability of their body wall/epithelia, specimens of Echinometra lucunter, Lytechinus variegatus, Paracentrotus gaimardi, and Arbacia lixula-A. lixula of two distinct populations, Rio de Janeiro and Santa Catarina-were abruptly transferred from 35 psu to either 25 or 45 psu. Sodium, chloride, magnesium, and potassium concentrations were assayed in their coelomic fluids after 0, 1, 2, and 3hr of exposure. Relative area of putative permeable (i.e., cross section areas of soft tissues, or test holes) surfaces (PPS) was estimated in empty tests as the sum of the peristomial area (oral hole in the empty test) and the total cross-section area of ambulacral holes, divided by the total volume (TV) of the test. L. variegatus and E. lucunter, the largest species, had PPS/TV values similar to that of the much smaller P. gaimardi. A. lixula was the "most putatively-permeable and conformer" among them all, especially urchins from the Santa Catarina population. Internal ionic levels equilibrated faster with external water in 45 than in 25, and differences among ions were observed. Body size is relevant, among many other factors, to aid conformers such as sea urchins to dwell in intertidal unstable habitats.

The role of size and dominance in the feeding behaviour of coexisting hummingbirds

Interspecific competition can strongly influence community structure and limit the distribution and abundance of species. One of the main factors that determine hummingbird community structure is competition for food. The temporal and spatial distribution of nectar has a strong impact on hummingbird assemblages, shaping foraging niches according to hummingbird dominance and foraging strategy. We investigated whether body size and the degree of aggressive dominance influence feeding behaviour of hummingbirds in a temperate forest in northwestern Mexico (El Palmito, Mexico) when winter migrant hummingbirds are present in the community. First, we determined the dominance status of hummingbirds and evaluated the relationship between dominance and body mass, wing disc loading and migratory status. Secondly, we determined how hummingbird species used plant species differently. Thirdly, we examined whether the most dominant hummingbird species defended floral patches with more energy and/or with a larger number of flowers. At each flower patch, hummingbird species, number of hummingbird interactions, feeding time and number of flowers present were recorded. The total number of calories available within each floral patch was also determined. Our results demonstrate that the dominance hierarchy of 13 hummingbird species (migratory and resident) was correlated with body size but not wing disc loading, and that members of the hummingbird community showed a clear separation in resource use (by plant species). Hummingbirds at the top of the dominance hierarchy defended and fed on the best flower patches, defined by the quantity of calories available. Hence, the feeding behaviour of hummingbirds at El Palmito depends on the abundance of plant species used by hummingbirds and on the amount of energy available from each flower patch. Thus, hummingbird body size, aggressive dominance and defence of quality flower patches determines niche partitioning among species.

Role of size, composition and substrate in controlling the reactivity of α(0001)-Al 2 O 3 supported Ag n Au m ( n+m = 2 − 4) alloy clusters for CO-oxidation: A comprehensive density functional study

Abstract Catalytic efficiency of gas phase and alumina-supported bimetallic Ag n Au m ( n + m = 2 − 4) alloy clusters is studied using density functional methods As a pre-requite, adsorption of O 2 and CO molecules, and co-adsorption of both molecules on these clusters are studied in detail. O 2 and CO are co-adsorbed on nearby sites on the gas phase tetramer clusters Ag 2 Au 2 and Ag 3 Au. But their catalytic efficiency is hindered by large barriers (1.55 eV and 1.44 eV, respectively) to the breaking of O O bond. Among the deposited clusters, Ag 2 Au and AgAu 2 have O 2 and CO co-adsorbed on nearby locations. Of these two, Ag 2 Au has a lower kinetic barrier for subsequent CO 2 formation. Thus Ag 2 Au looks the most promising candidate.

Superradiance from Two Dimensional Brick-Wall Aggregates of Dye Molecules: The Role of Size and Shape for the Temperature Dependence.

Aggregates of interacting molecules can exhibit electronically excited states that are coherently delocalized over many molecules. This can lead to a strong enhancement of the fluorescence decay rate which is referred to as superradiance (SR). To date, the temperature dependence of SR is described by a 1/T law. Using an epitaxial dye layer and a Frenkel-exciton based model we provide both experimental and theoretical evidence that significant deviations from the 1/T behavior can occur for brick-wall-type aggregates of finite size leading even to a maximum of the SR at finite temperature. This is due to the presence of low energy excitations of weak or zero transition strength. These findings are relevant for designing light-emitting molecular materials.

What drives export performance of firms in Eastern and Western Poland?

ABSTRACTWe use a unique firm-level survey dataset that draws from the EFIGE (European Firms in a Global Economy) questionnaire to unveil differences in factors driving export performance in the most structurally diverse areas of Poland. While conventional results regarding the role of size, foreign ownership and innovation activity are confirmed at the aggregate level, the picture breaks down when Western and Eastern macroregions are extracted. Our results suggest that the common perception of a more developed West (Poland ‘A’) and a backward East (Poland ‘B’) might be outdated. Rather, firms in both regions seem to follow distinct strategies for and have dissimilar success factors in competing internationally. Interestingly, export performance in the East is found to benefit from family ties in business, but also from product innovation and non-price competitiveness. In the West, it is associated mostly with size and foreign ownership. Overall, our results, on the one hand, add support to the ‘new’ new trade theory and the ‘new’ new economic geography’s premises related to the importance of microeconomic factors and, on the other, contribute to the discussion on the pattern of regional development in Poland. We also discuss some implications for policymakers and managers and suggest directions for further research.

Excitonic effects and related properties in semiconductor nanostructures: roles of size and dimensionality

The size- and dimensionality-dependence of excitonic effects and related properties in semiconductor nanostructures are theoretically studied in detail within the effective-mass approximation. When nanostructure sizes become smaller than the bulk exciton Bohr radius, excitonic effects are significantly enhanced with reducing size or dimensionality. This is as a result of quantum confinement in more directions leading to larger exciton binding energies and normalized exciton oscillator strengths. These excitonic effects originate from electron–hole Coulombic interactions, which strongly enhance the oscillator strength between the electron and hole. It is also established that the universal scaling of exciton binding energy versus the inverse of the exciton Bohr radius follows a linear scaling law. Herein, we propose a stretched exponential law for the size scaling of optical gap, which is in good agreement with the calculated data. Due to differences in the confinement dimensionality, the radiative lifetime of low-dimensional excitons becomes shorter than that of bulk excitons. The size dependence of the exciton radiative lifetimes is in good agreement with available experimental data. This strongly enhanced electron–hole exchange interaction is expected in low-dimensional structures due to enriched excitonic effects. The main difference in nanostructures compared to the bulk can be interpreted in terms of the enhanced excitonic effects induced by exciton localization. The enhanced excitonic effects are expected to be of importance in developing stable and high-efficiency nanoscale excitonic optoelectronic devices.

Variability in early post-settlement mortality in intertidal mussels and the role of size at settlement

ABSTRACTEarly post-settlement mortality is difficult to measure in mobile benthic taxa such as mussels. Field studies typically employ settlement collectors that often contain empty shells of dead individuals, which are usually disregarded. Here, empty shells of pediveligers, i.e. recent settlers that died before beginning to grow as juveniles, were used to assess temporal and spatial patterns of early mortality in mussels, whether size at settlement determined mortality, and whether mortality was density-dependent. This study took place at two intertidal sites in a large harbour in central New Zealand where monthly cohorts of mussels were collected over a 2-year period. Monthly mortality varied substantially, ranging from 0% to 42.6%, but not across the two sites that were 27 km apart. Although there was no density-dependent mortality evident within cohorts, the proportion of pediveligers which were dead on collection was highly positively correlated across sites. Live settlers were on average larger than dead settlers, and the size distribution of dead settlers was shifted toward smaller sizes compared to live settlers. At the extremes, of all settlers with shell length of 260 µm or less, 72% were dead on collection. By contrast, for settlers 310 µm or greater in length, 6% were dead. Together, these results (1) suggest that in this system size at settlement may be an important determinant of very early, peri-metamorphic mortality in mussels, with smaller settlers at higher risk, and (2) demonstrate the value in evaluating dead pediveligers for assessing natural early post-settlement mortality in mussels.

Molecular mechanisms of isocitrate dehydrogenase 1 (IDH1) mutations identified in tumors: The role of size and hydrophobicity at residue 132 on catalytic efficiency

Isocitrate dehydrogenase 1 (IDH1) catalyzes the reversible NADP+-dependent conversion of isocitrate (ICT) to α-ketoglutarate (αKG) in the cytosol and peroxisomes. Mutations in IDH1 have been implicated in >80% of lower grade gliomas and secondary glioblastomas and primarily affect residue 132, which helps coordinate substrate binding. However, other mutations found in the active site have also been identified in tumors. IDH1 mutations typically result in a loss of catalytic activity, but many also can catalyze a new reaction, the NADPH-dependent reduction of αKG to d-2-hydroxyglutarate (D2HG). D2HG is a proposed oncometabolite that can competitively inhibit αKG-dependent enzymes. Some kinetic parameters have been reported for several IDH1 mutations, and there is evidence that mutant IDH1 enzymes vary widely in their ability to produce D2HG. We report that most IDH1 mutations identified in tumors are severely deficient in catalyzing the normal oxidation reaction, but that D2HG production efficiency varies among mutant enzymes up to ∼640-fold. Common IDH1 mutations have moderate catalytic efficiencies for D2HG production, whereas rarer mutations exhibit either very low or very high efficiencies. We then designed a series of experimental IDH1 mutants to understand the features that support D2HG production. We show that this new catalytic activity observed in tumors is supported by mutations at residue 132 that have a smaller van der Waals volume and are more hydrophobic. We report that one mutation can support both the normal and neomorphic reactions. These studies illuminate catalytic features of mutations found in the majority of patients with lower grade gliomas.

A Study on Fundamentals as Determinants of Firm Value under Restriction of Size, Governance and Diversification

Firm value is present value of future cash flows expected from the firm – a basic theory of corporate valuation. Fundamental analysis is the one in which they try to find out variables that determine corporate cash flows and/or discount factors. We are especially interested in the role of size, governance and diversification in determination of firm value by fundamentals. We use Korean listed firms for our test. We document that firm value is positively and very significantly explained by fundamentals. Variables that are related to cash flows and/or discount factors are also found to significantly explain firm value. In addition, firm size and governance significantly affects firm value. Diversification strategy, however, is not significantly explaining firm value. It shows negative significance only in combination with R&D. In addition, our finding support that more cash flows and more R&D by larger firms will lead to higher firm value, and R&D by more diversified firms decreases firm value. Our findings would be helpful in designing good corporate policies on management of cash flows or capital structure to boost up firm value, or in managing stock portfolios.

The impact of pensions, transfers and taxes on child poverty in Europe: the role of size, pro-poorness and child orientation

We assess the impact of redistributive policy on child poverty across 29 European welfare states, using EU SILC 2005-2012. We distinguish between spending on pensions, spending on other cash transfers and taxation. For each of these instruments of redistribution, we further distinguish three features: size, pro-poorness and targeting towards households with children. Pensions are generally neglected in analyses on child poverty, but are relevant through the presence of two, partially offsetting, forces. Increased pension spending weakens the relative income position of children, but pensions also substantially contribute to the household income of children from multigenerational households. This ambiguous result signals a challenge: while reductions in pension spending may be desirable in the long run in several European welfare states, policymakers-especially in Southern and Eastern Europe-should be aware that this not only directly involves income losses for the elderly, but also for a non-negligible share of (predominantly poor) children.

Multiparametric Assessment of Gold Nanoparticle Cytotoxicity in Cancerous and Healthy Cells: The Role of Size, Shape, and Surface Chemistry.

In recent years, we and others have become interested in evaluating the use of surface-enhanced Raman scattering (SERS) tags for early cancer detection and in designing new approaches to demonstrate the applicability of this spectroscopic technique in the clinic. SERS-based imaging in particular offers ultra sensitivity up to the single molecule, multiplexing capability, and increased photostability and has been shown to outperform fluorescence. However, to employ SERS tags for early cancer detection, it is important to understand their interaction with cells and determine their cytotoxicity. We have been particularly interested for quite some time in determining if and how gold nanostars, which have been demonstrated as outstanding SERS enhancing substrates, can be safely employed in living systems and translated to the clinic. In this study, we carried out a multiparametric in vitro study to look at the cytotoxicity and cellular uptake of gold nanoparticles on human glioblastoma and human dermal fibroblast cell lines. Cytotoxicity was evaluated by incubating cells with three different morphologies of AuNPs, namely nanospheres, nanorods, and nanostars, each having three different surface chemistries (cetyltrimethylammonium bromide (CTAB), poly(ethylene glycol) (PEG), and human serum albumin (HSA)). Our results showed that the surface chemistry of the nanoparticles had predominant effects on cytotoxicity, and the morphology and size of the nanoparticles only slightly affected cell viability. CTAB-coated particles were found to be the most toxic to cells, and PEGylated nanostars were determined to be the least toxic. Caspase-3 assay and LDH assay revealed that cell death occurs via apoptosis for cancerous cells and via necrosis for healthy ones. Cellular uptake studies carried out via TEM showed that the particles retain their shape even at long incubation times, which may be beneficial for in vivo SERS-based disease detection. Overall, this study provides valuable information on gold-nanoparticle-induced cytotoxicity that can be leveraged for the development of safe and effective nanoparticle-based therapeutic and diagnostic systems.

The Role of Size in Development of Mucosal Liposome-Lipopeptide Vaccine Candidates Against Group A Streptococcus.

Group A streptococcus (GAS) is an exclusively human pathogenic bacteria. A delay in treatment of GAS infection often lead to severe diseases such as rheumatic heart disease which attributes to hundreds of thousands deaths annually. For the past few decades, the quest for a commercial GAS vaccine has been futile. Currently one of the most investigated strategies to develop vaccine against GAS includes the use of conserved epitopes from major virulent factor of GAS, M-protein. In this study, cationic liposomes of various sizes (70 nm to 1000 nm) were prepared with dimethyldioctadecylammonium bromide (DDAB) encapsulating lipopeptide bearing M-protein derived B-cell epitope (J14). Smaller liposomes induced higher antibody titres, though the differences between groups were not statistically significant. Nonetheless, all mice which were immunized with liposome-lipopeptide delivery system elicited high levels of systemic (IgG) and mucosal antibodies (IgA), which were discernably higher than those induced with the help of commercial adjuvant (cholera toxin B subunit).