Contribution Of Different Components Research Articles

Determination of the calorimetric energy in extensive air showers

The contribution of different components of an air shower to the total energy deposit in the atmosphere, for different angles and primary particles, was studied using the CORSIKA air shower simulation code. The amount of missing energy, parameterized in terms of the calorimetric energy, was calculated. The results show that this parameterization varies less than 1% with angle or observation level. The dependence with the primary mass is less than 5% and, with the high energy hadronic interaction model, less than 2%. The systematic error introduced by the use of just one parameterization of the missing energy correction function, for an equal mixture of proton and iron at 45°, was calculated to be below 3%. We estimate the statistical error due to shower-to-shower fluctuations to be about 1%.

Sampling variance of flood quantiles from the generalised logistic distribution estimated using the method of L-moments

Abstract. The method of L-moments is the recommended method for fitting the three parameters (location, scale and shape) of a Generalised Logistic (GLO) distribution when conducting flood frequency analyses in the UK. This paper examines the sampling uncertainty of quantile estimates obtained using the GLO distribution for single site analysis using the median to estimate the location parameter. Analytical expressions for the mean and variance of the quantile estimates were derived, based on asymptotic theory. This has involved deriving expressions for the covariance between the sampling median (location parameter) and the quantiles of the estimated unit-median GLO distribution (growth curve). The accuracy of the asymptotic approximations for many of these intermediate results and for the quantile estimates was investigated by comparing the approximations to the outcome of a series of Monte Carlo experiments. The approximations were found to be adequate for GLO shape parameter values between –0.35 and 0.25, which is an interval that includes the shape parameter estimates for most British catchments. An investigation into the contribution of different components to the total uncertainty showed that for large returns periods, the variance of the growth curve is larger than the contribution of the median. Therefore, statistical methods using regional information to estimate the growth curve should be considered when estimating design events at large return periods. Keywords: flood frequency analysis, Flood Estimation Handbook, single site, annual maximum series, Generalised Logistic Distribution, uncertainty

Effect of tertiary multileaf collimator (MLC) on foetal dose during three-dimensional conformal radiation therapy (3DCRT) of a brain tumour during pregnancy

Background and purpose The aim of this work was to measure the dose to foetus both in vivo and in vitro during three-dimensional conformal radiation therapy (3DCRT) in a pregnant patient with a pituitary adenoma. The study was then extended to assess the components contributing to the foetal dose such as collimator scatter, internal scatter, head leakage, wedge scatter and multileaf collimator (MLC) effect. Patients and methods A 30-year-old pregnant woman with a non-functioning pituitary macroadenoma was planned for 3DCRT with 6 MV X-ray using four equally weighted MLC-shaped non-coplanar wedged portals. In vivo dosimetry was carried out using thermoluminescent (TL) phosphor powder, which was placed at different positions on the patient, corresponding to different locations in the uterus and also at external os. In vitro measurements were also performed on a simulated phantom using the same set-up parameters and beam arrangement to verify the in vivo measured dose. Experiments were carried out to measure the respective contributions of different components towards peripheral dose. Results In vitro measured dose to foetus was found to be slightly more than that of in vivo measurement with a maximum of 0.044% of the prescribed dose of 45 Gy, which corresponded to 0.0199±0.0008 Gy. Thermoluminescence dosimeter (TLD) kept at the external os of the patient showed a dose of 0.031% of the prescribed dose. Among the various components of the peripheral dose (foetal dose) measured, head leakage was found to be the leading cause contributing 52%, followed by wedge scatter (31%), collimator scatter (14%) and internal scatter (13%). The use of MLC reduced not only the volume of normal brain irradiation as compared to open fields but also the peripheral dose by 10%. Conclusion Radiotherapy of brain tumours during pregnancy poses a unique clinical situation and decisions to deliver radiotherapy should be taken after detailed in vitro and in vivo dosimetric measurements. Our findings suggest that the beam arrangement using 3–4-fields generally used for 3DCRT of brain tumour with MLC for optimal coverage can be employed for pregnant patients even in early trimester. A possible increase in foetal dose from wedges to a large extent can be compensated with the use of MLC.

The geographical range structure of the holly leaf‐miner. II. Demographic rates

Summary Few studies have sought to document the variation in demographic rates exhibited by local populations across the geographical range of a species. None the less, such information has the potential to yield insights into the factors that determine the internal abundance structure of ranges. Major components of demographic rates are reported here for the holly leaf‐miner Phytomyza ilicis Curtis across its natural geographical range in Europe, including areas at each of the extreme limits and at the core of its occurrence. Correlograms reveal that a number of these components exhibit significant spatial structure across the geographical range and, in conjunction with interpolated maps, suggest that some of these patterns are, in terms of broad trends, reasonably simple. Across the whole range, individual mortality components are largely independent of one another and of leaf‐miner population densities, often exhibiting very different spatial patterns. Thus, P. ilicis populations experience markedly different mortality profiles across the range. While some correlations between broad‐scale environmental variation and the components of demographic rates were found, it was not possible to separate these effects from shared spatial structure. In sum, the contribution of different components of demographic rates to local densities varies markedly across the geographical range of P. ilicis, and in isolation the pattern observed in any one locality provides limited information on what is occurring elsewhere, but these components none the less often exhibit systematic geographical patterns of variation.

Characterization of the Apoptosis Suppressor Protein P49 from the Spodoptera littoralisNucleopolyhedrovirus

Two antiapoptotic types of genes, iap and p35, were found in baculoviruses. P35 is a 35-kDa protein that can suppress apoptosis induced by virus infection or by diverse stimuli in vertebrates or invertebrates. iap homologues were identified in insects and mammals. Recently, we have identified sl-p49, a novel apoptosis suppressor gene and the first homologue of p35, in the genome of the Spodoptera littoralis nucleopolyhedrovirus. Here we show that sl-p49 encodes a 49-kDa protein, confirmed its primary structure that displays 48.8% identity to P35, and performed computer-assisted modeling of P49 based on the structure of P35. We demonstrated that P49 is able to inhibit insect and human effector caspases, which requires P49 cleavage at Asp(94). Finally we identified domains important for P49's antiapoptotic function that include a reactive site loop (RSL) protruding from a beta-barrel domain. RSL begins at an amphipathic alpha1 helix, traverses the beta-sheet central region, exposing Asp(94) at the apex, and rejoins the beta-barrel. Our model predicted seven alpha-helical motifs, three of them unique to P49. alpha-Helical motifs alpha(1), alpha(2), and alpha(4') were required for P49 function. The high structural homology between P49 and P35 suggests that these molecules bear a scaffold common to baculovirus "apoptotic suppressor" proteins. P49 may serve as a novel tool to analyze the contribution of different components of the caspase chain in the apoptotic response in organisms not related phylogenetically.

Asymmetry coefficient for large optically soft spherical particles.

The basic mechanisms describing radiation scattered by large optically soft spheres are presented in this paper. The contributions of different components of geometrical optics to formation of the integral indicatrix have been estimated. The asymptotic equations for the asymmetry coefficient have been obtained.

Biomass and combustion characteristics of secondary mixed deciduous forests in Eastern Ghats of India

Biomass quantities at three different sites in tropical moist mixed secondary deciduous forests before and after burning have been quantified in the forest patches cleared for shifting cultivation purposes. The main objective of the experiments was to study the spatial variability in the amount of biomass burnt and the contribution of different components viz., bole, branch, and mixed leaf litter in the burning process affecting the combustion factors. Species composition at the three sites varied with respect to each other. The total density of species before burning at the three sites for more than 10 cm diameter were found to be 3192 (site 1), 1194 (site 2) and 1444 (site 3) stems/area, respectively. Analysis of the results from girth-class and density relationships suggests that nearly 80% of the stems occurred in the range from 10–40 cm girth for site one, 64.2% in 10–55 cm girth class for the site two and more than 80% of stems in 10–40 cm girth class for the site three, indicating very poor and secondary nature of the forest. The fire intensity is found to be high for site one with 60 847 kJ s −1 m −1, when compared to 31 086 and 42 789 kJ s −1 m −1 for second and third sites, respectively. The values are comparatively higher than the mean value of 2566 kJ s −1 m −1 reported for savanna fires. The individual combustion completeness suggested that among the different components of biomass, branch material with less than 10 cm and upto 5 cm dbh contributed to more than 60% of combustion. Mixed leaf litter contributed to about more than 50% of individual combustion completeness at all the sites, with third site having the highest (84%). The contribution of dry biomass material having more than 70 cm diameter is found to be very low indicating that most of the trunks were burnt superficially. The overall combustion completeness suggested that mixed leaf litter and branch material contributed to most of the combustion. Of all the three sites, site three had been found to be having highest combustion completeness of about 30.04% when compared to 20.18% and 16.1% for first and second sites, respectively. In the study, comparison of combustion factors for different vegetation types has also been made.

Roles of larval supply and behavior in determining settlement of barnacles in a temperate mangrove forest.

Recruitment is often a major influence on the spatial distribution of populations of benthic marine invertebrates, but the contributions of different components of recruitment are not well known, with the added complication that the relative importance of various life-history processes may be scale-dependent. Previously, we have shown that over a large scale across a mangrove (Avicennia marina) forest in southeastern Australia, settlement of the barnacle Elminius covertus explained its patterns of recruitment, which in turn explained the distribution of adults on mangrove pneumatophores. Post-settlement mortality had little influence on this pattern. In contrast, small-scale vertical distributions of adult barnacles along individual pneumatophores were determined by the pattern of recruitment, which differed from the pattern of settlement, so post-settlement mortality determined the vertical patterns of adults.In this study, we tested whether larval supply and/or settlement behavior influence the observed settlement patterns of E. covertus across a forest (from seaward to landward zones). We also tested whether larval supply could explain the vertical settlement patterns along the pneumatophores. A pumping system was used to collect cypris larvae from seaward, mid and landward zones of a mangrove forest and an adjacent, unvegetated shore and from three heights above the sediment surface. We also used transplantation of wooden stakes bearing microbial films and barnacle recruits between horizontal zones of the forest to determine whether settlement was influenced by these films or recruits.Both cyprid supply and cyprid behavior were important factors in determining the patterns of settlement of E. covertus across the forest. Cyprid supply was a result of three-fold differences in immersion times of different (landward, mid and seaward) zones across the forest and a decrease in density of cyprids in the water column from the seaward zone of the forest to the landward sections. In the absence of mangroves immediately adjacent to the forest, there was no temporally consistent difference in cyprid density across the shore and even the differences in immersion time did not produce consistent differences in cyprid supply across the shore. Wooden substrata that had been immersed at seaward sections of the forest attracted consistently more settlers than substrata immersed initially at other sections of the forest and settlement could be induced beyond the normal distribution of adults of E. covertus by stakes transplanted from the seaward zone.The vertical settlement pattern could not be explained by the supply of cyprids, suggesting that larval behavior must determine the vertical settlement pattern.

Influence of physicochemical conditions on amino acid adsorption on inorganic membranes

Inorganic Carbosep membranes with separation layer of zirconia powder were used in the present study to separate a fermentation medium. The contribution of different components of this medium to the membrane fouling was investigated. Yeast extract (YE) was found to be the main reason for the membrane fouling during ultrafiltration (UF) of the fermentation medium. The electrostatic interactions: membrane/solutes were estimated measuring zeta (ξ) potential of zirconia powders in contact with YE. Dynamic amino acid (AA) adsorption during ultrafiltration of yeast extract was assessed. Effect of pH, AA concentration, AA charge, and membrane charge modification on the retention and adsorption of free AA existing in the YE were studied.

Sources of dietary fluoride intake in 4-year-old children residing in low, medium and high fluoride areas in Iran

Accurate estimation of fluoride dietary intake is desirable for optimising caries prevention. Little is known about the dietary fluoride intake of children aged 4 years, an age when many permanent teeth are forming. This study was undertaken in Fars Province, Iran, in 1995-96, where there are big differences in temperature between winter and summer. The aims were to determine: (a) the relative contributions of different components of the diet to fluoride intake, (b) the effect of variation in fluoride concentration in drinking water, and (c) the effect of climate temperature. Temperature varied between +40°C in summer to -5°C in winter. The mean fluoride concentrations in drinking water in the three areas were 0.3, 0.6 and 4.0 mgF/L. Dietary information was obtained by two 3-day diet diaries with interview, validated with reference to international standards. The fluoride content of foods was measured using the silicon-facilitated diffusion method. One hundred and three 4-year-old children completed the study. The mean (and 95% confidence interval) dietary fluoride intakes in each of the three areas, respectively, were 413 (± 21), 698 (± 89) and 3472 (± 557) μ g/day. Drinks provided 72 to 87% of dietary fluoride - this proportion increased with increasing water fluoride concentration and increasing climate temperature. Tea (infusion) was an important source of dietary fluoride, providing 31 to 38% of total dietary intake. Tap water was a more important source of fluoride than soft drinks. Cooked rice and bread were the most important food source of fluoride and the amount of fluoride they contributed increased as water fluoride concentration increased. The results of this first such survey in the Middle East showed (a) that water (as a drink) and tea were by far the most important contributors to dietary fluoride intake, (b) substantial increases in fluoride intake with increasing water fluoride concentrations, and (c) substantially higher fluoride intakes in summer than in the winter.

Elevated CO2 and temperature impacts on different components of soil CO2 efflux in Douglas‐fir terracosms

AbstractAlthough numerous studies indicate that increasing atmospheric CO2 or temperature stimulate soil CO2 efflux, few data are available on the responses of three major components of soil respiration [i.e. rhizosphere respiration (root and root exudates), litter decomposition, and oxidation of soil organic matter] to different CO2 and temperature conditions. In this study, we applied a dual stable isotope approach to investigate the impact of elevated CO2 and elevated temperature on these components of soil CO2 efflux in Douglas‐fir terracosms. We measured both soil CO2 efflux rates and the 13C and 18O isotopic compositions of soil CO2 efflux in 12 sun‐lit and environmentally controlled terracosms with 4‐year‐old Douglas fir seedlings and reconstructed forest soils under two CO2 concentrations (ambient and 200 ppmv above ambient) and two air temperature regimes (ambient and 4 °C above ambient). The stable isotope data were used to estimate the relative contributions of different components to the overall soil CO2 efflux. In most cases, litter decomposition was the dominant component of soil CO2 efflux in this system, followed by rhizosphere respiration and soil organic matter oxidation. Both elevated atmospheric CO2 concentration and elevated temperature stimulated rhizosphere respiration and litter decomposition. The oxidation of soil organic matter was stimulated only by increasing temperature. Release of newly fixed carbon as root respiration was the most responsive to elevated CO2, while soil organic matter decomposition was most responsive to increasing temperature. Although some assumptions associated with this new method need to be further validated, application of this dual‐isotope approach can provide new insights into the responses of soil carbon dynamics in forest ecosystems to future climate changes.

SCALING ADDITIONAL CONTRIBUTIONS TO PRINCIPAL COMPONENTS ANALYSIS

Principal components analysis (PCA) is of great use in representation of multi-dimensional data sets, often providing a useful compression mechanism. Sometimes, input data sets are drawn from disparate domains, such that components of the input are heterogeneous, making them difficult to compare in scale. When this occurs, it is possible for one component to dominate another in the PCA at the expense of the information content of the original data. We present an approach to balancing the contributions of different components that is constructive; it generalises to the case of the addition of several variables. Conjectures about improved approaches and more complex data sets are presented. The approach is demonstrated on two current research applications.

Partitioning particulate light absorption: A budget for a Mediterranean bay

The contribution of different components of the plankton (autotrophs and heterotrophic bacteria, heterotrophic flagellates, and mixo‐ and heterotrophic ciliates) and suspended inorganic particles to light absorbed by particles in a Mediterranean bay was examined based on a 2‐year time series of particulate light absorption (400–700, 400, and 675 nm), the biomass of planktonic microorganisms, and the mass of suspended inorganic particles. The average (±SE) particulate light absorption coefficient for the photosynthetically active radiation (PAR) range (0.035 ± 0.002 m−1) was characteristic of relatively clear coastal waters but showed great variability on occasions. A substantial fraction (53–73%, depending on the wavelength examined) of this variability could be accounted for by changes in the abundance of inorganic suspended matter, as well as planktonic organisms. The specific light absorption by autotrophs was less variable over the three spectral bands considered than those of microheterotrophs and inorganic particles, which dropped sharply with increasing wavelength. Inorganic particles contributed, on the average, 48 and 74% of the total particulate absorption for the PAR waveband and at 400 nm, respectively, with their contribution to light absorption at 675 nm being negligible. Autotrophs dominated light absorption at 675 nm (on average 45.8% of total particulate absorption), whereas mixo‐ and heterotrophic ciliates and bacteria together contributed, on average, 22.5% of the total light absorption at this wavelength. The combined light absorption coefficient of microheterotrophs at 400 nm (0.0126 m−1) was similar to that of autotrophs (0.013 m−1). These results documented the dominant role that inorganic particles play in the absorption of blue light in the Bay of Blanes and showed that the particulate light absorption by autotrophs was often comparable to that of heterotrophs.

A review of diagnostic emission line ratios in the Narrow Line Region of Active Galactic Nuclei

AbstractThe availability of new observing facilities both from ground and space such as the Keck 10m telescope and the Hubble Space Telescope is casting new light on the spectroscopic investigation of emission line galaxies. In particular, it is now possible to detect spectra with a significantly improved signal to noise ratio in a very wide wavelength range, from the ultraviolet to the near infrared (HST, Keck) and beyond (ISO is unveiling the far infrared domain). As we move to high redshifts, however, it is more likely that the observed spectra are given by the contribution of different components in the galaxy: in particular, this may be the case if an Active Galactic Nucleus (AGN hereafter) emitting a power‐law continuum is surrounded by regions with strong star formation activity. The identification of the source which ionizes the line emitting regions is then complicated by the fact that we are observing the integrated spectrum from regions which are ionized by different sources. In this paper we wish to review which line ratios may be used in order to discriminate between photoionization by young stars and power‐law continuum in the wavelength range from 1200 Å to 100 μm. To this aim we used the photoionization code Cloudy (Ferland 1996) to present a series of diagnostic diagrams showing the dependence of emission line ratios on the main input parameters of photoionization models in the case of one component models with gaseous clouds ionized by (1) a stellar continuum typical of an HII region and (2) a power‐law continuum typical of an AGN: these line ratios are plotted as isoratio maps for different values of the hydrogen density, ionization parameter and slope of the power‐law continuum. We then show how the results may be affected by more realistic assumptions about the environment of the ionized gas: to this aim, we show the effects on selected line ratios of (a) the presence of two populations of clouds with different densities and (b) an AGN surrounded by regions with strong star formation activity.

The activities of acidic and glutamine-rich transcriptional activation domains in plant cells: design of modular transcription factors for high-level expression.

The aim of this work was to design strong transcriptional activators that can be used to regulate plant gene expression. The contribution of different components in a transcription factor and target gene system was assayed by measuring transcriptional activation. Each component was optimised to achieve maximal reporter gene expression in transient protoplast transformation assays. The DNA-binding domain of the yeast transcriptional activator GAL4 was studied in the context of fusion proteins with activation domains of the herpes simplex virus protein VP16 or the tomato Myb-like activator THM18. Multimerisation of the activation domain and insertion of a homopolymeric glutamine stretch was used to increase transcription factor potency. Evidence is presented that these modifications can result in even more active transcription factors when they are combined. Finally, it was demonstrated using competition experiments that transcription factors with acidic activation domains can mutually suppress their activation potentials when expressed at high levels.

Reactivation of HIV type 1 in chronically infected chimpanzees following xenostimulation with human cells or with pulses of corticosteroid.

Following resolution of a primary HIV-1 infection initially induced by inoculating a mixture of three different virus strains, a chimpanzee was exposed to both immunostimulatory and immunosuppressive agents in an attempt to assess the contributions of different components of the immune system in suppressing circulating virus. The infusion of human leukocytes as an xenogeneic stimulus induced the replication of one of the input virus strains that had not previously been isolated or detected by PCR. The administration of high-dose, 17-day courses of corticosteroids resulted in coordinate and transient increases of each of the three viruses present in the original inoculum and elevation of HIV-1-specific ELISA antibody levels. Steroids administered to a second chimpanzee, chronically infected with a single HIV-1 isolate, also induced elevations of cell-associated virus. These results highlight the intimate relationship between immune system activation/immunosuppression and HIV replication in an animal model.

IRASObservations of the Outer Galaxy. I. Discrete Sources and Large‐Scale (Diffuse) Emission

The infrared emission in two fields of the outer Galaxy is analyzed using the IRAS image data. We present a census of discrete (but extended) IRAS sources, identified from the 60 μm images. This sample can be used to characterize the properties of typical star-forming regions.We distinguish class A sources (Galactic star-forming regions) from other Galactic objects on the basis of their flux density distributions. However, our class A sources have different infrared colors than other star formation groups (young stellar objects [YSOs] and ultracompact H II regions), as measured by the IRAS Point Source Catalogue. The class A colors, in particular the high 12 μm/25 μm ratio, are similar to the color sequence found by Boulanger et al. for the O-star-excited California Nebula. They are also similar to the colors measured, on IRAS image products, for larger classical H II regions embedded in large molecular clouds. The similar infrared colors suggest that most class A sources are larger, lower density regions that sample a variety of local radiation field strengths.The infrared colors of class A sources are also found to match the colors of normal spiral galaxies. This suggests that a close correspondence exists between the physical conditions in outer Galaxy star-forming regions and normal spiral galaxies.The discrete sources have been carefully measured on IRAS Coadd images, and detailed comparisons are made with the results from other IRAS data products, especially with the Point Source Catalog (PSC). Great care has been taken to investigate the uncertainties associated with these measurements, and these results may be useful for other studies that make use of IRAS image products.Information from these measurements is combined with larger scale IRAS images to investigate the relative contributions of different components of the outer Galaxy to the total mid- and far-infrared emission. At 60 and 100 km, the diffuse emission (i.e., infrared cirrus) dominates the emission from the discrete sources, which include all possible sites of star formation.

Different Components in Word-List Forgetting of Pure Amnesics, Degenerative Demented and Healthy Subjects

This study investigated the contribution of different components of the serial position curve to the accelerated forgetting rate displayed by amnesic and degenerative demented patients in word-list recall. For this purpose, we analyzed immediate and 15 min delayed recall performances on Rey's 15-word learning task of 16 pure amnesic, 15 Alzheimer's demented and 81 healthy subjects. Results documented that in all groups most forgetting occurred at the expense of terminal items of the word list. Nevertheless, both amnesic and demented patients showed a disproportionately larger memory loss on the recent part of the serial position curve than healthy subjects. Finally, amnesics (but not AD patients) suffered from a significantly larger forgetting rate for primacy items than normal controls. These data demonstrate that a critical deficit in memory disordered patients is represented by a failure in transferring information from a transitory memory status to a more durable storing condition. At least in amnesic patients, our results also suggest “true” long-term forgetting, presumably due to decay or to the intervening inaccessibility of previously stored memory representations.

Hypervirial approach to calculating expectation values of the many-body Hamiltonian.

We present a new method, based on the hypervirial operator, for calculating expectation values of many-body Hamiltonians for local velocity-independent potentials. Our approach enables us to calculate the contributions of different components of an interaction [e.g., tensor, one pion exchange part (OPEP)] to the binding energy when {ital all} components are acting. In particular, using the integro-differential equation approach we investigate the contributions of different components of realistic nucleon-nucleon potentials to the triton and {alpha} particle ground-state binding energies. Although the tensor force contributes the most to the expectation value of the potential energy, we find that its overall contribution to the binding energy is much reduced by its large contribution to the expectation value of the kinetic energy.

Vitamins: The Tortuous Path from Needs to Fantasies

The discovery of vitamins in the early 1900s, their chemical characterization and the clarification of their metabolic functions are sequential aspects of a brilliant chapter in the history of modern nutritional science. Despite our current knowledge about vitamins, inadequate vitamin status still abounds in the less industrialized world. With some vitamins, toxicity also poses a problem. The average daily amounts of dietary vitamins needed to maintain physiological functions in generally healthy persons is fairly well known. Nonetheless, new indicators of vitamin status and in vivo kinetic analysis should allow refinement of these values. The dietary intake of fruits and vegetables has been associated with a decreased risk of major chronic diseases, including cancer and cardiovascular diseases. The specific contributions of different components of the diet, including several vitamins, to this apparent protective effect is still uncertain. Factors besides diet that affect chronic diseases are lifestyle, genetics, medical awareness, and habits like smoking. Fantasies among generally healthy persons that large supplements of any single vitamin or combination of them, like some magical amulet, will significantly stave off ill health have captivated a sizable percentage of our population. Such beliefs can only be changed, if at all, by appropriate educational messages based on convincing scientific data.