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This paper presents the distribution of the number of customers served during a busy period for special cases of the Geo/G/1 queue when initiated with m customers. We analyze the system under the assumptions of a late arrival system with delayed access and early arrival system policies. It is not easy to invert the functional equation for the number of customers served during a busy period except for the simple case Geo/Geo/1 queue, as stated by several researchers. Using the Lagrange inversion theorem, we give an elegant solution to this equation. We find the distribution of the number of customers served during a busy period for various service-time distributions such as geometric, deterministic, binomial, negative binomial, uniform, Delaporte, discrete phase-type and interrupted Bernoulli process. We compute the mean and variance of these distributions and also give numerical results. Due to the clarity of the expressions, the computations are very fast and robust. We also show that in the limiting case, the results tend to the analogous continuous-time counterparts.
We present a detailed overview of the cosmological surveys that we aim to carry out with Phase 1 of the Square Kilometre Array (SKA1) and the science that they will enable. We highlight three main surveys: a medium-deep continuum weak lensing and low-redshift spectroscopic HI galaxy survey over 5 000 deg2; a wide and deep continuum galaxy and HI intensity mapping (IM) survey over 20 000 deg2 from
$z = 0.35$
to 3; and a deep, high-redshift HI IM survey over 100 deg2 from
$z = 3$
to 6. Taken together, these surveys will achieve an array of important scientific goals: measuring the equation of state of dark energy out to
$z \sim 3$
with percent-level precision measurements of the cosmic expansion rate; constraining possible deviations from General Relativity on cosmological scales by measuring the growth rate of structure through multiple independent methods; mapping the structure of the Universe on the largest accessible scales, thus constraining fundamental properties such as isotropy, homogeneity, and non-Gaussianity; and measuring the HI density and bias out to
$z = 6$
. These surveys will also provide highly complementary clustering and weak lensing measurements that have independent systematic uncertainties to those of optical and near-infrared (NIR) surveys like Euclid, LSST, and WFIRST leading to a multitude of synergies that can improve constraints significantly beyond what optical or radio surveys can achieve on their own. This document, the 2018 Red Book, provides reference technical specifications, cosmological parameter forecasts, and an overview of relevant systematic effects for the three key surveys and will be regularly updated by the Cosmology Science Working Group in the run up to start of operations and the Key Science Programme of SKA1.
The objectives of the current study were to investigate the dynamics of body calcium (Ca) and to estimate the net Ca maintenance requirements (NCam) of Saanen goats, using 45Ca as a radiotracer. Eighteen castrated male Saanen goats (25 ± 2.3 kg body weight (BW)) received a basal diet (ground ear maize, ground maize and vitamin–mineral premix). The treatments consisted of adding limestone to the basal diet to provide Ca content of 0.6, 1.7 and 3.0 g/kg dry matter (DM). The experiment lasted 45 days (i.e. 36 d of adaptation and 9 days of measurements). On day 38, 0.5 ml of 7.4 MBq 45Ca solution was administrated before feeding. From days 39 to 45, samples of faeces, blood and urine were collected, and Ca concentration determined. The Ca intake, Ca in faeces, Ca in urine, faecal endogenous Ca and true absorbed Ca increased linearly as Ca content in the diets increased, while retained Ca increased at a decreasing rate. Dry matter intake decreased at an increasing rate with increased Ca content in the diets. In contrast, Ca content in the diets did not affect biological availability of Ca, or Ca in plasma. The true biological availability of Ca from limestone in Saanen goats was 0.72. The daily NCam was 11.6 (±1.3) mg/kg BW. The current results might help to understand Ca dynamics in goats and enhance the formulation of balanced diets to best meet Ca requirements of Saanen goats.
The Dark Energy Survey is undertaking an observational programme imaging 1/4 of the southern hemisphere sky with unprecedented photometric accuracy. In the process of observing millions of faint stars and galaxies to constrain the parameters of the dark energy equation of state, the Dark Energy Survey will obtain pre-discovery images of the regions surrounding an estimated 100 gamma-ray bursts over 5 yr. Once gamma-ray bursts are detected by, e.g., the Swift satellite, the DES data will be extremely useful for follow-up observations by the transient astronomy community. We describe a recently-commissioned suite of software that listens continuously for automated notices of gamma-ray burst activity, collates information from archival DES data, and disseminates relevant data products back to the community in near-real-time. Of particular importance are the opportunities that non-public DES data provide for relative photometry of the optical counterparts of gamma-ray bursts, as well as for identifying key characteristics (e.g., photometric redshifts) of potential gamma-ray burst host galaxies. We provide the functional details of the DESAlert software, and its data products, and we show sample results from the application of DESAlert to numerous previously detected gamma-ray bursts, including the possible identification of several heretofore unknown gamma-ray burst hosts.
Spectroscopic redshift surveys are an incredibly valuable tool in cosmology, allowing us to trace the distribution of galaxies as a function of distance and, thus, trace the evolution of structure formation in the Universe. However, estimating the redshifts from spectra with low signal-to-noise is difficult, and such data are often either discarded or require human classification of spectral lines to obtain the galaxy redshift. Darth Fader offers an automated method for estimating the redshifts of galaxies in the low signal-to-noise regime. Using a sophisticated, wavelet-based technique, galaxy spectra can be separated into continuum, line and noise components, and the lines can then be cross-correlated with template spectra in order to estimate the redshifts. Cross-matching of the identified lines then allows for a cleaning of the resulting catalogue, effectively removing the vast majority of erroneous redshift estimates and resulting in a highly pure, highly accurate redshift catalogue. Darth Fader allows us to effectively use low signal-to-noise galaxy spectra, and dramatically reduces the number of human hours required to do this, allowing spectroscopic surveys to probe deeper into the formation history of the Universe.
The problem of supernova photometric identification is still an open issue faced by large photometric surveys. In a previous investigation, we showed how combining Kernel Principal Component Analysis and Nearest Neighbour algorithms enable us to photometrically classify supernovae with a high rate of success. In the present work, we demonstrate that the introduction of Gaussian Process Regression (GPR) in determining each light curve highly improves the efficiency and purity rates. We present detailed comparison with results from the literature, based on the same simulated data set. The method proved to be satisfactorily efficient, providing high purity (⩽ 96%) rates when compared with standard algorithms, without demanding any information on astrophysical properties of the local environment, host galaxy or redshift.
This study examined the production of three types of noun plural inflections, feminine sound plural (FSP), masculine sound plural (MSP), and broken plural (BP) in Kuwaiti Arabic-speaking children with and without language impairment. A total of thirty-six Kuwaiti participants – twelve adults, twelve children with specific language impairment (SLI), and twelve typically developing age-matched controls (TD) were presented with twenty-seven pictured stimuli of real and nonsense words. The results showed that the TD children were significantly more accurate in using the required noun plural inflections than the SLI group. The TD children's preferred overgeneralization strategy was to substitute FSP for the regular MSP and irregular BP contexts much more than their peers with SLI. The performance of the SLI group also differed from that of their age-matched counterparts in the number of errors and their distribution across categories. The results are discussed in the light of relevant theories of atypical language development.
The over-dependency and misuse of the chemotherapeutic drugs available to parasite control with consequent development of anthelmintic resistance, mainly in small ruminants, has been demanded alternative sources to control gastrointestinal nematodes in sheep. The aim of the present study was to investigate the potential anthelmintic effects of condensed tannins (CT) from acacia extract (AE) on Trichostrongylus colubriformis in experimentally infected sheep.
The availability of nutrients in low concentration in diets is difficult to be accessed by means of experiments like apparent digestibility assays. That is because the endogenous contribution underestimates the true availability. The best tool to study the true availability of minerals is the in vivo isotopic dilution technique. Phosphorus (P) and calcium (Ca) are the most studied minerals due to their great importance in animal nutrition. P is one of the most polluting nutrients because of high husbandry concentrations in restricted areas (Tamminga, 1992). There are some remaining doubts concerning the true digestibility of phosphorus. The present study compiles data from previous studies dealing with true availability of different P sources in beef cattle to estimate pollution potential of animal excretions.
We are reporting here on the current status of our investigations on the time evolution of nanoscale surface morphology of thermally evaporated tungsten carbide coatings on silicon carbide substrates. The purpose of the study is to develop a recipe for creating thermally and chemically stable electrical contacts on silicon carbide electronic devices able to work at elevated temperatures (up to 800 °C) in oxidizing environments. We used thermal evaporation and tungsten carbide (WC) powder as a starting material to produce the thin layer deposition on semi-insulating silicon carbide (6H). Our intended applications are for devices working at 800 °C; therefore, our investigations are carried out at 1 hr intervals of time the samples spent at this temperature, in air at atmospheric pressure. We used Rutherford Backscattering Spectrometry (RBS) for measuring the stoichiometry and depth profile, and Atomic Force Microscopy (AFM) to monitor the surface morphology change.
Ruminal fermentation produces methane (CH4), which represents a loss of feed energy and a significant source of greenhouse gas. Researches have been searching for ways of inhibiting ruminal CH4 yield and promising results have been achieved in in vitro assays (Hu et al., 2005). The in vitro gas production technique can predict the in vivo enteric CH4 production from ruminants. Our research focused on the effect of 2-Bromoethanesulfonic acid (BES) on gas and CH4 production and microbial variation of Lucerne and Tifton-85 hays fermented in vitro.
The isotope dilution technique is the most important way to study the metabolism of minerals. With the use of radiophosphorus (32P), it is possible to describe the kinetics of P including the endogenous fraction. The aim of this work was to study the metabolism of supplemented P using the isotope dilution technique and to apply bio mathematical model to investigate its kinetics.
Calcium is needed for bone formation, muscle contraction, nerve transmission and a variety of other functions in the organism. Experiments has been carried out to study phosphorus metabolism in sheep and cattle, by using isotope dilution techniques however, there is very little information on Ca metabolism in sheep. The objective of this experiment was to study the effects of various Ca sources on the Ca flows in sheep by two models.
Although some argument is still ongoing about the resistance to different anthelmintics, there is a general agreement that reversion to susceptibility is rare once drug resistance (DR) has developed in livestock helminths, even when other drugs with completely different working mechanisms are used for prolonged periods. Some in vitro methods have been used to investigate the efficacy of towards nematode parasite: larval development (LD), larval migration inhibition (LMI), larval feeding inhibition (LFI) and egg hatch (EH) assays (Amarante et al. , 1997; Coles et al., 1988). The aim of this work was to determine the potential inhibitory effect of condensed tannins or other bioactive compounds from Acacia molissima extract on the feeding of first stage larvae of Haemonchus contortus, Trichostrongylus vitrinus and Teladorsagia circumcincta, using the LFI test.
Researches worldwide have been studying ruminal methane production in vitro and the in vitro gas production technique has demonstrated an ability to predict the in vivo enteric methane production from ruminants (Getachew et al., 2005; Tavendale et al., 2005). Studies of rumen microbial ecology in animals fed with tannin rich plants have demonstrated that tannins can affect rumen ecology. The objective of this study was to measure methane (CH4) production of Brazilian tannin rich plants incubated in vitro.
The continuing need of protein sources for the human population aside of the economic world is of considerable social interest, so the rational use of the local fauna has both economic and social advantages, while protecting wild species from extinction through irrational hunting and habitat destruction. Among Brazilian mammals the capybara is a big rodent, with high reproductive potential, are herbivorous, they increase their digestive efficiency through extensive mastication followed by fermentation by cellulolitic bacteria and protozoa in the cecum (González-Jiménez, 1995). Furthermore, capybaras are able to use microbial protein from the cecum after fermentation through the cecotrophy, or ‘reingestion’ of the cecal content (Mendes et al., 2000). In function of the controversial findings regarding cecotrophy in capybaras, this study was conducted to compare the faecal excretion curves of capybara, collared peccary (Tayassu tajacu) - animal that does not accomplish the cecotrophy, and rabbit (Oryctolagus cuniculus) - animal that accomplishes the cecotrophy.