1,113 research outputs found
Amblyomma vikirri Keirans, Bull and Duffield 1996
No full text136. Amblyomma vikirri Keirans, Bull and Duffield, 1996. An Australasian species, all stages of which are known only to parasitize Squamata: Scincidae. M: Keirans et al. (1996c) F: Keirans et al. (1996c) N: Keirans et al. (1996c) L: Keirans et al. (1996c) Redescriptions: none Note: Keirans et al. (1996c) state that morphological criteria are not useful for differentiating the larva of Amblyomma vikirri from those of Amblyomma limbatum and Amblyomma glauerti.Published as part of Guglielmone, Alberto A., Petney, Trevor N. & Robbins, Richard G., 2020, Ixodidae (Acari: Ixodoidea): descriptions and redescriptions of all known species from 1758 to December 31, 2019, pp. 1-322 in Zootaxa 4871 (1) on page 129, DOI: 10.11646/zootaxa.4871.1.1, http://zenodo.org/record/442334
Large deviations and overflow probabilities for the general single-server queue, with applications
No full textWe consider from a thermodynamic viewpoint queueing systems where the workload process is assumed to have an associated large deviation principle with arbitrary scaling: there exist increasing scaling functions (a_t, v_t, t ϵ R_+) and a rate function I such that if (W_t, t ϵ R_+) denotes the workload process, then lim_(t→∞) (v_t)^(-1)logP(W_t/a_t > w) = -I(w) on the continuity set of I. In the case that a_t = v_t = t it has been argued heuristically, and recently proved in a fairly general context (for discrete time models) by Glynn and Whitt [8], that the queue-length distribution (that is, the distribution of supremum of the workload process Q = sup_(t≥0) W_t) decays exponentially: P(Q > b) ~ e^(-δb) and the decay rate δ is directly related to the rate function I. We establish conditions for a more general result to hold, where the scaling functions are not necessarily linear in t: we find that the queue-length distribution has an exponential tail only if lim_(t→∞) a_t/v_t is finite and strictly positive; otherwise, provided our conditions are satisfied, the tail probabilities decay like P(Q > b) ~ e^(-δv(a^(-1)(b))). We apply our results to a range of workload processes, including fractional Brownian motion (a model that has been proposed in the literature (see, for example, Leland et al [10] and Norros [13]) to account for self-similarity and long range dependence) and, more generally, Gaussian processes with stationary increments. We also show that the martingale upper bound estimates obtained by Daley and Duffield [5], when the workload is modelled as an Ornstein-Uhlenbeck position process, are asymptotically correct
A large deviation principle for the reduction of product representations
No full textA large deviation principle is proved for a family of measures
{
L
n
:
n
=
1
,
2
,
…
}
\left \{ {{\mathbb {L}_n}:n = 1,2, \ldots } \right \}
derived from the multiplicities occurring in the decomposition into irreducible components of
n
n
-fold tensor products of representations of arbitrary compact semisimple Lie groups.</p
Lexical-Semantic Development in a Second Language: Investigating the adjective different in English and Japanese
No full textThe current study examined the second language (L2) acquisition of a specific case of one-to-many mapping, the adjective different and its two partially synonymous Japanese translations, betubetu and tigau. This particular example was recognised by Duffield, Matsuo and Wood (2005) who reported findings from Japanese native-speakers indicating that the word betubetu is more restricted in meaning than both different and tigau, and that English L2 learners were likely to overextend its use. Duffield et al.’s results had broad scope for interpretation and the present study investigated their significance within a framework of first language (L1) to L2 semantic transfer. Two experiments were conducted to explain English L2 learners’ performance at a lexically-specific level as well as to inform on the processes generally underlying L2 semantic development. A novel-word learning task and a magnitude estimation study of semantic acceptability used cross-linguistic comparisons of English and German learners to identify L1 dependencies in L2 behaviour. Methodological difficulties limited the explanatory potential of the novel-word task but magnitude estimation showed significant differences between native-speaker and L2 learner acceptability judgements consistent with the involvement of L1 semantic preferences in L2 lexical processing. As numbers in the study were small and learners varied in their L2 experience, the extent to which these deviations directly reflected L1 semantic influences could not be firmly concluded. However, their implications for current approaches to semantic development are discussed
Increased maternal nutrition alters development of the appetite-regulating network in the brain
No full textIndividuals exposed to an increased nutrient supply before birth have a high risk of becoming obese children and adults. It has been proposed that exposure of the fetus to high maternal nutrient intake results in permanent changes within the central appetite regulatory network. No studies, however, have investigated the impact of increased maternal nutrition on the appetite regulatory network in species in which this network develops before birth, as in the human. In the present study, pregnant ewes were fed a diet which provided 100% (control, n =8) or ∼160% (well-fed, n=8) of metabolizable energy requirements. Ewes were allowed to lamb spontaneously, and lambs were sacrificed at 30 days of postnatal age. All fat depots were dissected and weighed, and expression of the appetite-regulating neuropeptides and the leptin receptor (OBRb) were determined by in situ hybridization. Lambs of well-fed ewes had higher glucose (Glc) concentrations during early postnatal life (F=5.93, P<0.01) and a higher relative subcutaneous (s.c.) fat mass at 30 days of age (34.9±4.7 g/kg vs. 22.8±3.3 g/kg; P<0.05). The hypothalamic expression of pro-opiomelanocortin was higher in lambs of well-fed ewes (0.48±0.09 vs. 0.28±0.04, P<0.05). In lambs of overnourished mothers, but not in controls, the expression of OBRb was inversely related to total relative fat mass (r2=0.50, P=0.05, n=8), and the direct relationship between the expression of the central appetite inhibitor CART and fat mass was lost. The expression of neuropeptide Y and AGRP was inversely related to total relative fat mass (NPY, r2=0.28, P<0.05; agouti-related peptide, r2=0.39, P<0.01). These findings suggest that exposure to increased nutrition before birth alters the responses of the central appetite regulatory system to signals of increased adiposity after birth.—Muhlhausler, B. S., Adam, C. L., Findlay, P. A., Duffield, J. A., and McMillen, I. C. Increased maternal nutrition alters development of the appetite-regulating network in the brain.B. S. Muhlhausler, C. L. Adam, P. A. Findlay, J. A. Duffield and I. C. McMille
Intramolecular aromatic substitution reactions in substituted N,N-dimethylthiobenzamide ions
No full textRamana DV, Grützmacher H-F. Intramolecular aromatic substitution reactions in substituted N,N-dimethylthiobenzamide ions. Organic Mass Spectrometry. 1981;16(5):227-235
Predicting Qos Parameters For Atm Traffic Using Shape-Function Estimation.
No full textThis paper addresses the provisioning of service capacity and buffer space in an ATM multiplexer of a large number of VBR sources. The aim is to guarantee sufficient quality of service (QoS), specified here in terms of the cell loss ratio (CLR), while at the same time making maximal use of system resources. Multiplexing gain is available in shared resources due to the statistical properties of the individual traffic streams which share the resources. For example, if one doubles the number of (identical) sources to be multiplexed, one need not, generally, double the rate and buffer size in order to maintain the same CLR. Our method is to use empirical traffic statistics, which could be measured online, in order to predict these multiplexing gains. The prediction is done on the basis of the following scaling behaviour of queue-tail probabilities which has been shown to hold for a very general class of traffic models [1, 2, 4]. For an infinite buffer fed by N independent identical sources served at rate Ns, the frequency with which the queue
Economies of Scale in Queues With Sources Having Power-Law Large Deviation Scalings.
No full textWe analyse the queue Q L at a multiplexer with L sources which may display long-range dependence. This includes, for example, sources modelled by fractional Brownian Motion (fBM). The workload processes W due to each source are assumed to have large deviation properties of the form P [W t =a(t) ? x] ß e \Gammav(t)K(x) for appropriate scaling functions a and v, and ratefunction K. Under very general conditions, lim L!1 L \Gamma1 log P [Q L ? Lb] = \GammaI (b) provided the offered load is held constant, where the shape function I is expressed in terms of the cumulant generating functions of the input traffic. For power-law scalings v(t) = t v , a(t) = t a (such as occur in fBM) we analyse the asymptotics of the shape function: lim b!1 b \Gammau=a i I(b) \Gamma ffi b v=a j = u for some exponent u and constant depending on the sources. This demonstrates the economies of scale available through the multiplexing of a large number of such sources, by comparison with ..
A note on queues with M/G/∞ input
No full textWe consider a fluid queue fed by sessions, arriving according to a Poisson process; a session has a heavy-tailed duration, during which traffic is sent at a constant rate. We scale Poisson input rate Λ, buffer space B, and link rate C by n, such that we get nλ,nb , and nc, respectively. Then we let n grow large. In this regime, the overflow probability decays exponentially in the number of sources n; we examine the specific situation in which b is also large.In Duffield (Queueing Syst. 28 (1998) 245–266) this setting is considered. A crucial role was played by the function ≔v(t)≔−logP(D★>t) for large t,D★ being the residual session duration. Duffield covers the case that v(·) is regularly varying of index strictly between 0 and 1 (e.g., Weibull); this note treats slowly varying v(·) (e.g., Pareto, Lognormal).The proof adds insight into the way overflow occurs. If v(·) is slowly varying then, during the trajectory to overflow, the input rate will exceed the link rate only slightly. Consequently, the buffer will fill ‘slowly’, and the typical time to overflow will grow ‘faster than linearly’ in the buffer size. This is essentially different from the ‘Weibull case’, where the input rate will significantly exceed the link rate, and the time to overflow is essentially proportional to the buffer size. In both cases there is a substantial number of sessions that remain in the system during the entire path to overflow.</p
Maternal overnutrition suppresses the phosphorylation of 5 '-AMP-activated protein kinase in liver, but not skeletal muscle, in the fetal and neonatal sheep
No full textEpidemiological studies have shown that infants exposed to an increased supply of nutrients before birth are at increased risk of type 2 diabetes in later life. We have investigated the hypothesis that fetal overnutrition results in reduced expression and phosphorylation of the cellular fuel sensor, AMP-activated kinase (AMPK) in liver and skeletal muscle before and after birth. From 115 days gestation, ewes were fed either at or 55% above maintenance energy requirements. Postmortem was performed on lamb fetuses at 139–141 days gestation (n = 14) and lambs at 30 days of postnatal age (n = 21), and liver and quadriceps muscle were collected at each time point. The expression of AMPK1 and AMPK2 mRNA was determined by quantitative RT-PCR (qRT-PCR). The abundance of AMPK and phospho-AMPK (P-AMPK) was determined by Western blot analysis, and the proportion of the total AMPK pool that was phosphorylated in each sample (%P-AMPK) was determined. The ratio of AMPK2 to AMPK1 mRNA expression was lower in fetuses compared with lambs in both liver and muscle, independent of maternal nutrition. Hepatic %P-AMPK was lower in both fetuses and lambs in the Overfed group and %P-AMPK in the lamb liver was inversely related to plasma glucose concentrations in the first 24 h after birth (r = 0.73, P < 0.025). There was no effect of maternal overnutrition on total AMPK or P-AMPK abundance in liver or skeletal muscle. We have, therefore, demonstrated that AMPK responds to signals of increased nutrient availability in the fetal liver. Suppression of hepatic AMPK phosphorylation may contribute to increased glucose production, and basal hyperglycemia, present in lambs of overfed ewes in early postnatal life.L. K. Philp, B. S. Muhlhausler, A. Janovska, G. A. Wittert, J. A. Duffield, and I. C. McMille
- …
