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Search Results: 1 - 10 of 127163 matches for " Simon T Segar "
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A Role for Parasites in Stabilising the Fig-Pollinator Mutualism
Derek W. Dunn,Simon T. Segar,Jo Ridley,Ruth Chan,Ross H. Crozier,Douglas W. Yu,James M. Cook
PLOS Biology , 2012, DOI: 10.1371/journal.pbio.0060059
Abstract: Mutualisms are interspecific interactions in which both players benefit. Explaining their maintenance is problematic, because cheaters should outcompete cooperative conspecifics, leading to mutualism instability. Monoecious figs (Ficus) are pollinated by host-specific wasps (Agaonidae), whose larvae gall ovules in their “fruits” (syconia). Female pollinating wasps oviposit directly into Ficus ovules from inside the receptive syconium. Across Ficus species, there is a widely documented segregation of pollinator galls in inner ovules and seeds in outer ovules. This pattern suggests that wasps avoid, or are prevented from ovipositing into, outer ovules, and this results in mutualism stability. However, the mechanisms preventing wasps from exploiting outer ovules remain unknown. We report that in Ficus rubiginosa, offspring in outer ovules are vulnerable to attack by parasitic wasps that oviposit from outside the syconium. Parasitism risk decreases towards the centre of the syconium, where inner ovules provide enemy-free space for pollinator offspring. We suggest that the resulting gradient in offspring viability is likely to contribute to selection on pollinators to avoid outer ovules, and by forcing wasps to focus on a subset of ovules, reduces their galling rates. This previously unidentified mechanism may therefore contribute to mutualism persistence independent of additional factors that invoke plant defences against pollinator oviposition, or physiological constraints on pollinators that prevent oviposition in all available ovules.
A Role for Parasites in Stabilising the Fig-Pollinator Mutualism
Derek W Dunn,Simon T Segar,Jo Ridley,Ruth Chan,Ross H Crozier,Douglas W Yu,James M Cook
PLOS Biology , 2008, DOI: 10.1371/journal.pbio.0060059
Abstract: Mutualisms are interspecific interactions in which both players benefit. Explaining their maintenance is problematic, because cheaters should outcompete cooperative conspecifics, leading to mutualism instability. Monoecious figs (Ficus) are pollinated by host-specific wasps (Agaonidae), whose larvae gall ovules in their “fruits” (syconia). Female pollinating wasps oviposit directly into Ficus ovules from inside the receptive syconium. Across Ficus species, there is a widely documented segregation of pollinator galls in inner ovules and seeds in outer ovules. This pattern suggests that wasps avoid, or are prevented from ovipositing into, outer ovules, and this results in mutualism stability. However, the mechanisms preventing wasps from exploiting outer ovules remain unknown. We report that in Ficus rubiginosa, offspring in outer ovules are vulnerable to attack by parasitic wasps that oviposit from outside the syconium. Parasitism risk decreases towards the centre of the syconium, where inner ovules provide enemy-free space for pollinator offspring. We suggest that the resulting gradient in offspring viability is likely to contribute to selection on pollinators to avoid outer ovules, and by forcing wasps to focus on a subset of ovules, reduces their galling rates. This previously unidentified mechanism may therefore contribute to mutualism persistence independent of additional factors that invoke plant defences against pollinator oviposition, or physiological constraints on pollinators that prevent oviposition in all available ovules.
A Note on Linear based Set Associative Cache address System
Chandramowliswaran N,Srinivasan.S,Chandra Segar.T
International Journal on Computer Science and Engineering , 2012,
Abstract: Based on the system request or application request a set of word is loaded on the cache memory. When the system is switched off the cache history gets abscond. The performance of CPU is based on the factors such as cache hit, write through cache, write back, cache memory mapping technique, CPU speed, bandwidth, cache memory size etc., Some of the standard cache addresses mapping techniques are set associative, associative and direct mapping technique. This paper proposes a novel idea of set associative cache address mapping usinglinear equation. The standard set associative mapping is remapped with linear set associative for to secure the data in a non sequential portion by having the standard mapping execution time. This is mainly focus on to design the cache enhancement and improvement.
Small deviations in p-variation norm for multidimensional Levy processes
T. Simon
Mathematics , 2003,
Abstract: Let Z be an Rd-valued Levy process with strong finite p-variation for some p<2. We prove that the ''decompensated'' process Y obtained from Z by annihilating its generalized drift has a small deviations property in p-variation. This property means that the null function belongs to the support of the law of Y with respect to the p-variation distance. Thanks to the continuity results of T. J. Lyons/D. R. E. Williams, this allows us to prove a support theorem with respect to the p-Skorohod distance for canonical SDE driven by Z without any assumption on Z, improving the results of H. Kunita. We also give a criterion ensuring the small deviation property for Z itself, noticing that the characterization under the uniform distance, which we had obtained in a previous paper, no more holds under the p-variation distance.
Small deviations in p-variation for stable processes
T. Simon
Mathematics , 2003,
Abstract: Let $\{Z_t, t\geq 0\}$ be a strictly stable process on $\R$ with index $\alpha\in (0,2]$. We prove that for every $p > \alpha$, there exists $\gamma = \gamma (\alpha, p)$ and $\k = \k (\alpha, p)\in (0, +\infty)$ such that $$\lim_{\ee\downarrow 0}\ee^{\gamma}\log\pb\lcr ||Z||_{p}\leq \ee \rcr = - \k,$$ where $||Z||_{p}$ stands for the strong $p$-variation of $Z$ on $[0,1]$. The critical exponent $\gamma (\alpha, p)$ takes a different shape according as $|Z|$ is a subordinator and $p >1$, or not. The small ball constant $\k (\alpha, p)$ is explicitly computed when $p \leq 1$, and a lower bound on $\k (\alpha, p)$ is easily obtained in the general case. In the symmetric case and when $p > 2$, we can also give an upper bound on $\k (\alpha, p)$ in terms of the Brownian small ball constant under the $(1/p)$-H\"older semi-norm. Along the way, we remark that the positive random variable $||Z||^p_{p}$ is not necessarily stable when $p > 1$, which gives a negative answer to an old question of P.~E.~Greenwood.
Adiabatic thermostatistics of the two parameter entropy and the role of Lambert's W-function in its applications
R. Chandrashekar,J. Segar
Physics , 2012, DOI: 10.1016/j.physa.2013.05.045,
Abstract: A unified framework to describe the adiabatic class of ensembles in the generalized statistical mechanics based on Schwammle-Tsallis two parameter (q, q') entropy is proposed. The generalized form of the equipartition theorem, virial theorem and the adiabatic theorem are derived. Each member of the class of ensembles is illustrated using the classical nonrelativistic ideal gas and we observe that the heat functions could be written in terms of the Lambert's W-function in the large N limit. In the microcanonical ensemble we study the effect of gravitational field on classical nonrelativistic ideal gas and a system of hard rods in one dimension and compute their respective internal energy and specific heat. We found that the specific heat can take both positive and negative values depending on the range of the deformation parameters, unlike the case of one parameter Tsallis entropy.
Jordanian quantum spheres
R. Chakrabarti,J. Segar
Mathematics , 2001, DOI: 10.1142/S0217732301004832
Abstract: We introduce and investigate a one parameter family of quantum spaces invariant under the left (right) coactions of the group-like element ${\cal T}_{h}^{(j=1)}$ of the Jordanian function algebra $Fun_{h}(SL(2))$. These spaces may be regarded as Jordanian quantization of the two-dimensional spheres.
A Survey on Context-Aware Sensing for Body Sensor Networks  [PDF]
Barbara T. Korel, Simon G. M. Koo
Wireless Sensor Network (WSN) , 2010, DOI: 10.4236/wsn.2010.28069
Abstract: Context awareness in Body Sensor Networks (BSNs) has the significance of associating physiological user activity and the environment to the sensed signals of the user. The context information derived from a BSN can be used in pervasive healthcare monitoring for relating importance to events and specifically for accurate episode detection. In this paper, we address the issue of context-aware sensing in BSNs, and survey different techniques for deducing context awareness.
Reflections on urban space: streets through time Reflections on urban space: streets through time
Simon T. Loseby
Reti Medievali Rivista , 2011, DOI: 10.6092/1593-2214/305
Abstract: This paper offers a general reflection on late antique and early medieval urban space, situating the essays in the collection Le trasformazioni dello spazio urbano nell’alto medioevo (secoli V-VIII). Città mediterranee a confronto (RM Rivista 2010, 2) within a wider framework. It focuses in particular on the long late antique phase of Mediterrranean urban history, and the enduring ideological significance of urbanism in the early medieval west. Il contributo offre una riflessione generale sullo spazio urbano in età tardo antica e alto medievale, collocando i saggi della raccolta Le trasformazioni dello spazio urbano nell’alto medioevo (secoli V-VIII). Città mediterranee a confronto (RM Rivista 2010, 2) in un più largo contesto. Il contributo si sofferma in particolare sulla lunga fase antica della storia mediterranea urbana e sul perdurante significato ideologico dell’urbanesimo nell’Occidente alto medievale.
Comparison of the Bacterial Microbiota in a Bale of Collected Cardboard Determined by 454 Pyrosequencing and Clone Library  [PDF]
Valérie Lalande, Simon Barnabé, Jean-Charles C?té
Advances in Microbiology (AiM) , 2014, DOI: 10.4236/aim.2014.412082
Abstract: Biofouling, the accumulation of microorganisms, is a major problem in paper mills processing paper and cardboard. This leads to the production of lower quality recycled products. Several studies have focused on the microbial content in the paper mill and the final products. Our aim was to determine the microbial biota in a bale of collected cardboard prior to entering the paper mill. Total genomic DNA was isolated and analyzed using two different methods for comparison purposes: 454 pyrosequencing and clone library. A total of 3268 V6-V8 454 pyrosequencing reads and 322 cloned V6-V8 16S rRNA nucleotide sequences were obtained. Both methods showed the presence of three major bacterial genera: Bacillus, Solibacillus and Paenibacillus, all members of the spore-forming phylum Firmicutes. Pyrosequencing, however, revealed a richer and more diverse bacterial community than clone library. It showed the presence of additional minor Firmicute genera and of a small number of Proteobacteria. The sorting at the recycling plant, the storing, and the processing at the paper mill, the end uses, will all contribute to the bacterial microbiota present in a bale of collected cardboard as revealed here.
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