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Search Results: 1 - 10 of 516351 matches for " A. W. Watson "
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Contrasting Micro/Nano Architecture on Termite Wings: Two Divergent Strategies for Optimising Success of Colonisation Flights
Gregory S. Watson, Bronwen W. Cribb, Jolanta A. Watson
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0024368
Abstract: Many termite species typically fly during or shortly after rain periods. Local precipitation will ensure water will be present when establishing a new colony after the initial flight. Here we show how different species of termite utilise two distinct and contrasting strategies for optimising the success of the colonisation flight. Nasutitermes sp. and Microcerotermes sp. fly during rain periods and adopt hydrophobic structuring/‘technologies’ on their wings to contend with a moving canvas of droplets in daylight hours. Schedorhinotermes sp. fly after rain periods (typically at night) and thus do not come into contact with mobile droplets. These termites, in contrast, display hydrophilic structuring on their wings with a small scale roughness which is not dimensionally sufficient to introduce an increase in hydrophobicity. The lack of hydrophobicity allows the termite to be hydrophilicly captured at locations where water may be present in large quantities; sufficient for the initial colonization period. The high wettability of the termite cuticle (Schedorhinotermes sp.) indicates that the membrane has a high surface energy and thus will also have strong attractions with solid particles. To investigate this the termite wings were also interacted with both artificial and natural contaminants in the form of hydrophilic silicon beads of various sizes, 4 μm C18 beads and three differently structured pollens. These were compared to the superhydrophobic surface of the planthopper (Desudaba psittacus) and a native Si wafer surface. The termite cuticle demonstrated higher adhesive interactions with all particles in comparison to those measured on the plant hopper.
Diversity of a semi-arid, intact Mediterranean ecosystem in southwest Australia
S. Judd, J. E. M. Watson,A. W. T. Watson
Web Ecology (WE) , 2008, DOI: 10.5194/we-8-84-2008
Abstract: The drier parts of the Mediterranean biome of southwest Australia contain the largest remaining Mediterranean woodlands and shrublands on Earth. Despite this, there has been no formal, comprehensive assessment of their biodiversity. The region abuts the southwest Australian floristic region which has received much scientific attention. The aim of this paper is to provide the first general overview of the biodiversity of part of this intact, yet relatively unknown, Mediterranean ecosystem. We do this by synthesizing data from State Government agencies and published research. We found that, like other parts of southwest Australia, the region has globally significant levels of plant species diversity. More than 2400 plant species, including 291 species considered threatened, have been recorded, representing one-sixth of all Australia’s vascular plant species. Eleven of Australia’s 23 major vegetation groups are represented even though the region covers less than 1% of continental Australia. We documented 170 vertebrate species, including 31 threatened species, with a particularly high richness of reptile species (n = 46). We highlight how little is known about this region. For example, 116 vertebrate species not recorded in the region probably occur there based on their habitat requirements and known distributions. An examination of plant and vertebrate diversity in the region, using a half degree latitude and longitude grid cells, showed a highly heterogeneous pattern of species richness and vulnerability, with a general decline in species richness from southwest to northeast. Conservation strategies that rely on capturing the highest levels of biodiversity in a series of protected areas are unlikely to guarantee protection for all species given these high levels of heterogeneity. Instead, a region-wide conservation plan should involve targeted ecological research, consideration of ecological processes and stakeholder consultation.
Particle Adhesion Measurements on Insect Wing Membranes Using Atomic Force Microscopy
Gregory S. Watson,Bronwen W. Cribb,Jolanta A. Watson
ISRN Biophysics , 2012, DOI: 10.5402/2012/947872
Abstract:
Anti Inflammatory Effects of Statins in Cardiac Surgery Patients  [PDF]
A. Raza, S. Kennedy, Y. Fan, B. Maher, M. Codd, T. Murphy, A. Wood, W. Watson
World Journal of Cardiovascular Surgery (WJCS) , 2012, DOI: 10.4236/wjcs.2012.23010
Abstract: Objectives: Cardiac surgery with cardiopulmonary bypass provokes systemic inflammatory response, which may cause organ dysfunction. Studies have suggested that pre-operative statin therapy can reduce morbidity and mortality associated with cardiac surgery; the mechanism for this remains unclear. We hypothesise that underlying mechanism of action for these effects of statins is through inhibition of neutrophil transendothelial migration. Methods: We recruited 151 patients undergoing cardiac surgery. Of these 41 patients were on no-statin; 48 patients on low-dose (10 - 30 mg) and 62 patients were on high-dose statin (40 - 80 mg). Ex vivo neutrophil migration was performed on pre-operative blood samples of 90 patients. Of these 90 patients we used 36 patients to assess the levels of TNF-α and sICAM-1. Clinical parameters of total 151 patients were assessed to analyse outcome. Results: Ex vivo neutrophil migration was decreased in high-dose statin group when compared to neutrophils isolated from no-statin or low-dose statin groups (p < 0.001). Serum TNF-α levels were lower in the high-dose statin group (p = 0.002) and sICAM-1 levels were decreased in both low (p = 0.02) and high-dose statin (p = 0.01) groups. Conclusion: Our study demonstrates that high-dose statins reduce ex-vivo transendothelial neutrophil migration, TNF-α and sICAM-1 serum levels suggesting that statins may help in decreasing the post-cardiac surgery morbidity.
Adiabatic self-trapped states in carbon nanotubes
L. Brizhik,A. Eremko,B. Piette,M. Watson,W. Zakrzewski
Physics , 2005,
Abstract: We study here polaron (soliton) states of electrons or holes in a model describing carbon-type nanotubes. In the Hamiltonian of the system we take into account the electron-phonon interaction that arises from the deformation dependencies of both the on-site and the hopping interaction energies. Using an adiabatic approximation, we derive the equations for self-trapped electron states in zigzag nanotubes. We find the ground states of an electron in such a system and show that the polaron states can have different symmetries depending on the strength of the electron-phonon coupling. Namely, at relatively weak coupling the polarons possess quasi-one-dimensional (quasi-1D) properties and have an azimuthal symmetry. When the coupling constant exceeds some critical value, the azimuthal symmetry breaks down and the polaron spreads out in more than one dimension. We also study polarons that are formed by the electrons in the conducting band (or by holes in the valence band) in semiconducting carbon nanotubes. We show that their properties are more complex than those of quasi-1D ground state polarons. In particular, polarons in semiconducting carbon nanotubes possess an inner structure: being self-trapped along the nanotube axis they exhibit some modulations around the nanotube.
Gaussian Spectral Line Profiles of Astrophysical Masers
W. D. Watson,A. P. Sarma,M. S. Singleton
Physics , 2002, DOI: 10.1086/340833
Abstract: Calculations are performed to demonstrate the deviations from Gaussian that occur in the spectral line profiles of a linear maser as a result of the amplification process. Near-Gaussian profiles are presented for bright, interstellar 22 GHz water masers obtained from high resolution Very Long Baseline Array (VLBA) observations of W3 IRS 5. For the profiles to be so close to Gaussian, the calculations indicate that these masers must originate in quite hot gas with temperatures greater than 1200 K -- a conclusion that is supportive of C-type shocks as the origin of these masers. In addition, the degree of saturation of these masers must be less than approximately one-third, from which it follows that the beaming angles are less than about 10^{-4} ster and the actual luminosities are modest. If spectral profiles that are as close to Gaussian as the profiles presented in this initial investigation are found to occur widely, they can be valuable diagnostics for the environments of astrophysical masers.
Reaping Numbers of Boolean Algebras
A. Dow,J Steprāns,W. S. Watson
Mathematics , 1992,
Abstract: A subset $A$ of a Boolean algebra $B$ is said to be $(n,m)$-reaped if there is a partition of unity $P \subset B$ of size $n$ such that the cardinality of $\{b \in P: b \wedge a \neq \emptyset\}$ is greater than or equal to $m$ for all $a\in A$. The reaping number $r_{n,m}(B)$ of a Boolean algebra $B$ is the minimum cardinality of a set $A \subset B\setminus \{0\}$ such which cannot be $(n,m)$-reaped. It is shown that, for each $n \in \omega$, there is a Boolean algebra $B$ such that $r_{n+1,2}(B) \neq r_{n,2}(B)$. Also, $\{r_{n,m}(B) : \{n,m\}\subseteq\omega\}$ consists of at most two consecutive integers. The existence of a Boolean algebra $B$ such that $r_{n,m}(B) \neq r_{n',m'}(B)$ is equivalent to a statement in finite combinatorics which is also discussed.
Lithography and Fabrication of Frictional Tiers on Poly(Dimethylsiloxane) Using Atomic Force Microscopy  [PDF]
Gregory S. Watson, Jolanta A. Watson
Journal of Surface Engineered Materials and Advanced Technology (JSEMAT) , 2012, DOI: 10.4236/jsemat.2012.223036
Abstract: This study investigates controlled micro/nano manipulation of polydimethylsiloxane (PDMS) using Atomic Force Microscopy (AFM). Lithographic results revealed stick-slip phenomena along the slow scan direction. Varying the normal loading force, scan size, scan number and contact conditions allowed the control of certain lithographic outcomes e.g., channel spacing. The PDMS surface experienced significant in-plane deformation in response to the tip-induced lateral force. This displacement increased with increasing loading force, creating greater spacing between channels in the slow scan direction. Simultaneous generation of a lateral displacement in the fast scan direction caused a decrease in channel length with increasing loading force due to an increase in static friction with normal force, resulting in a greater surface relaxation, and shorter track length of dynamic friction. By controlling both the loading force and the number of scans over an area, frictional tiers were produced.
Henoch Schonlein Purpura – A 5-Year Review and Proposed Pathway
Louise Watson, Amanda R. W. Richardson, Richard C. L. Holt, Caroline A. Jones, Michael W. Beresford
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0029512
Abstract: Henoch Schonlein Purpura (HSP) is the commonest systemic vasculitis of childhood typically presenting with a palpable purpuric rash and frequently involving the renal system. We are the first group to clinically assess, critically analyse and subsequently revise a nurse led monitoring pathway for this condition. A cohort of 102 children presenting with HSP to a secondary/tertiary level UK paediatric hospital over a five year period, were monitored using a nurse led care pathway. Using this cohort, the incidence (6.21 cases per 100,000 children per year) and natural disease course of HSP nephritis (46% initial renal inflammation; 9% subsequent renal referral; 1% renal biopsy and immunosuppression) was determined. Older patients were at higher risk of requiring a renal referral (renal referral 12.3 (8.4–13.5) years vs. normal outcome 6.0 (3.7–8.5) years; p<0.01). A normal urinalysis on day 7 had a 97% (confidence interval 90 to 99%) negative predictive value in predicting a normal renal outcome. Using this data and existing literature base, The Alder Hey Henoch Schonlein Purpura Pathway was developed, a revised pathway for the screening of poor renal outcome in HSP. This is based on a six-month monitoring period for all patients presenting with HSP, which importantly prioritises patients according to the urine findings on day 7 and thus intensively monitors those at higher risk of developing nephritis. The pathway could be easily adapted for use in different settings and resources. The introduction of a standardised pathway for the monitoring of HSP will facilitate the implementation of disease registries to further our understanding of the condition and permit future clinical trials.
Consistency of long-term elemental carbon trends from thermal and optical measurements in the IMPROVE network
L.-W. A. Chen, J. C. Chow, J. G. Watson,B. A. Schichtel
Atmospheric Measurement Techniques (AMT) & Discussions (AMTD) , 2012,
Abstract: Decreasing trends of elemental carbon (EC) have been reported at US Interagency Monitoring of PROtected Visual Environments (IMPROVE) network from 1990 to 2004, consistent with the phase-in of cleaner engines, residential biomass burning technologies, and prescribed burning practices. EC trends for the past decade are examined due to an upgrade of IMPROVE carbon instruments and the thermal/optical analysis protocol since 2005. Filter reflectance (τR) values measured as part of the carbon analysis were retrieved from archived data and compared with EC for 65 sites with more complete records within 2000–2009. EC–τR relationships suggest minor changes of EC quantified by the original and upgraded instruments for most IMPROVE samples. EC and τR show universal decreasing trends across the US. The EC and τR trends are correlated, with national average downward rates (relative to the 2000–2004 baseline medians) of 4.5% yr 1 for EC and 4.1% yr 1 for τR. The consistency between independent EC and τR measurements adds to the weight of evidence that EC reductions are real rather than an artifact of changes to the measurement process.
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