740 research outputs found
THE CALCULATIONS OF LOW-ENERGY BEAM TRANSPORT
No full textAfter the ion beams are extracted from ion sources, it is necessary to transport the beams to the experimental areas or to the accelerating installations. Low-energy beam transport systems usually consist of some axially symmetrical electrostatic focusing and accelerating lenses as well as quadrupoles and dipoles. Here, we discuss the calculation methods for the beam transport in electrostatic lens systems and describe a computer program for this use.Instruments & InstrumentationPhysics, AppliedSCI(E)
Producing space, producing China : a critical intervention
No full textThe concepts of the production and representation of space and place are receiving an increasing amount of attention in both the humanities and the social sciences. This paper will use the theoretical knowledge that has and continues to be produced on the subject to come
to a better understanding of the spatial origins that constitute the place that is Chinese nation
state. The analysis of spatial practises should shed light on the question what China is and wherefrom it receives the legitimacy for its social-spatial integrity.
It will be argued that the arrival of modernity and its universal measurement of time and space were essential components in the gradual transformation from ethnocentric place to a territorially defined nation state. The political production and organisation of space employed for the formation of the nation state is argued to be the consequence of the same (globalising) logic that is now said to question and undermine its territorial integrity.
Modernity and globalisation are in this paper, in other words, considered to be similar, if not identical, spatial-temporal concepts that both help to create and destruct places. This is arguably best visible in the constant production and reproduction of the most sophisticated of spatial organisations: our cities. I will argue that despite the changing face of cities, of which the disputed contemporary "globalisation" is but one of many, the spatial reality that is the modern nation state remains the same. This is not to return to an orthodox realist interpretation but to understand the very "stuff" that space and place are made of
Soliton solutions for quasilinear Schrodinger equations, I
No full textFor a class of quasilinear Schrodinger equations we establish the existence of ground states of soliton type solutions by a minimization argument.Mathematics, AppliedMathematicsSCI(E)95ARTICLE2441-44813
Physical–chemical characterisation of the particulate matter inside two road tunnels in the São Paulo Metropolitan Area
No full textabstract: The notable increase in biofuel usage by the road transportation sector in Brazil during recent years has significantly altered the vehicular fuel composition. Consequently, many uncertainties are currently found in particulate matter vehicular emission profiles. In an effort to better characterise the emitted particulate matter, measurements of aerosol physical and chemical properties were undertaken inside two tunnels located in the São Paulo Metropolitan Area (SPMA). The tunnels show very distinct fleet profiles: in the Jânio Quadros (JQ) tunnel, the vast majority of the circulating fleet are light duty vehicles (LDVs), fuelled on average with the same amount of ethanol as gasoline. In the Rodoanel (RA) tunnel, the particulate emission is dominated by heavy duty vehicles (HDVs) fuelled with diesel (5% biodiesel). In the JQ tunnel, PM[subscript 2.5] concentration was on average 52 μg m[superscript −3], with the largest contribution of organic mass (OM, 42%), followed by elemental carbon (EC, 17%) and crustal elements (13%). Sulphate accounted for 7% of PM[subscript 2.5] and the sum of other trace elements was 10%. In the RA tunnel, PM[subscript 2.5] was on average 233 μg m[superscript −3], mostly composed of EC (52%) and OM (39%). Sulphate, crustal and the trace elements showed a minor contribution with 5%, 1%, and 1%, respectively. The average OC : EC ratio in the JQ tunnel was 1.59 ± 0.09, indicating an important contribution of EC despite the high ethanol fraction in the fuel composition. In the RA tunnel, the OC : EC ratio was 0.49 ± 0.12, consistent with previous measurements of diesel-fuelled HDVs. Besides bulk carbonaceous aerosol measurement, polycyclic aromatic hydrocarbons (PAHs) were quantified. The sum of the PAHs concentration was 56 ± 5 ng m[superscript −3] and 45 ± 9 ng m[superscript −3] in the RA and JQ tunnel, respectively. In the JQ tunnel, benzo(a)pyrene (BaP) ranged from 0.9 to 6.7 ng m[superscript −3] (0.02–0.1‰ of PM[subscript 2.5)] whereas in the RA tunnel BaP ranged from 0.9 to 4.9 ng m[superscript −3] (0.004–0. 02‰ of PM[subscript 2.5]), indicating an important relative contribution of LDVs emission to atmospheric BaP.This article and any associated published material is distributed under the Creative Commons Attribution 3.0 License. View the article as published at: http://www.atmos-chem-phys.net/13/12199/2013
A new approach to probing primordial non-Gaussianity
No full text08/02/13 meb Publisher version attached, OK to pub
Fracture energy of columnar freshwater ice: Influence of loading type, loading rate and size
No full textFunding Information: This work was funded though the Finland Distinguished Professor programme ”Scaling of Ice Strength: Measurements and Modeling”, and through the ARAJ research project, both funded by Business Finland and the industrial partners Aker Arctic Technology, Arctech Helsinki Shipyard, Arctia Shipping, ABB Marine, Finnish Transport Agency, Suomen Hyȵtytuuli Oy, and Ponvia Oy. This financial support is gratefully acknowledged. The second author (J.P.D.) thanks Business Finland for support by the FiDiPro Professorship from Aalto University, and the sabbatical support from Aalto University, which collectively supported an annual visit 2015–2016, and summer visits 2017–2019. Publisher Copyright: © 2021 The Author(s)This work investigates the influence of loading type, loading rate, and test size on the fracture energy of columnar freshwater S2 ice. The ice sheet in the Ice tank at Aalto University was very warm (above -0.5 ∘C) and thick (0.34<h<0.41 m). A program of nineteen mode I fracture tests using deeply cracked edge-cracked rectangular plates of various sizes (size range 1:39), loading types, and loading rates were carried out. Fourteen displacement-controlled tests (DC) were loaded monotonically to fracture, and five load-controlled tests (LC) were conducted with creep/cyclic-recovery and monotonic loading to fracture. Different methods for computing the fracture energy were applied and compared. The apparent fracture energy at crack growth initiation was obtained via Rice's J-integral expression (JQ) modified to be applicable to the special case of a deeply cracked edge-cracked plate as well as via a viscoelastic fictitious crack analysis (GVFCM). The work-of-fracture (Wf) was also evaluated. Both JQ and Wf were measured from the load-displacement record at the crack mouth. GVFCM was obtained from the back-calculated stress-separation (σ−δ) relation within the fracture process zone. A rather good agreement was obtained between GVFCM and JQ, especially for the large specimens. JQ and Wf exhibited interrelated size and rate effects. The Wf/JQ values for the DC tests were affected by rate and confined to a narrow range of 1 to 3. The creep-recovery loading did not affect the JQ values but led to an increase in the Wf and Wf/JQ values for most of the LC tests.Peer reviewe
Small fish swimming in the shape of a shark: why politicians join political parties in the Pacific islands
No full textPolitical parties are ubiquitous features of contemporary models of representative democracy and are widely believed to be integral to transition, and yet persistently democratic Pacific Island countries tend to have ‘weakly’ institutionalised parties – some have none at all – that have little influence on the mobilisation of voters during elections. Party theory largely assumes that politicians form parties to win elections: the author asks why, given the commonly cited irrelevance of party politics in much of the Pacific, politicians join political parties at all. Drawing on 96 biographical accounts – including 72 in-depth interviews –he interprets the explanations politicians give for joining, leaving and changing parties. The author identifies three narratives. The first accords with an augmented rational actor model, the second with a responsible parties model and the third points to intrinsic motivations that are largely overlooked in the existing literature. The author concludes that a comprehensive account must include all three interpretations
A real-time information gathering agent based on ontology
No full textThis paper provides an agent based on an ontology that helps user to gather the real-time information. We present an approach of ontology representation based on concept graph and introduce the building and revising algorithms of knowledge base, then discuss the application of the ontology in information source representation. Experimental results show that the agent helps user accomplish the task effectively.Computer Science, Information SystemsComputer Science, Theory & MethodsSCI(E)CPCI-S(ISTP)
Phylogeography and allopatric divergence in cypress species (Cupressus L.) in the Qinghai-Tibetan Plateau and adjacent regions
No full textAdditional files can be found at http://www.biomedcentral.com/1471-2148/10/194Background Although allopatric speciation is viewed as the most common way in which species originate, allopatric divergence among a group of closely related species has rarely been examined at the population level through phylogeographic analysis. Here we report such a case study on eight putative cypress (Cupressus) species, which each have a mainly allopatric distribution in the Qinghai-Tibetan Plateau (QTP) and adjacent regions. The analysis involved sequencing three plastid DNA fragments (trnD-trnT, trnS-trnG and trnL-trnF) in 371 individuals sampled from populations at 66 localities. Results Both phylogenetic and network analyses showed that most DNA haplotypes recovered or haplotype-clustered lineages resolved were largely species-specific. Across all species, significant phylogeographic structure (NST > GST, P < 0.05) implied a high correlation between haplotypes/lineages and geographic distribution. Two species, C. duclouxiana and C. chengiana, which are distributed in the eastern QTP region, contained more haplotypes and higher diversity than five species with restricted distributions in the western highlands of the QTP. The remaining species, C. funebris, is widely cultivated and contained very little cpDNA diversity. Conclusions It is concluded that the formation of high mountain barriers separating deep valleys in the QTP and adjacent regions caused by various uplifts of the plateau since the early Miocene most likely promoted allopatric divergence in Cupressus by restricting gene flow and fixing local, species-specific haplotypes in geographically isolated populations. The low levels of intraspecific diversity present in most species might stem from population bottlenecks brought about by recurrent periods of unfavorable climate and more recently by the negative impacts of human activities on species' distributions. Our findings shed new light on the importance of geographical isolation caused by the uplift of the QTP on the development of high plant species diversity in the QTP biodiversity hotspot.Peer reviewe
Toxicity and in vitro activity of HIV-1 latency-reversing agents in primary CNS cells
No full textDespite the success of combination antiretroviral therapy (cART), HIV persists in long lived latently infected cells in the blood and tissue, and treatment is required lifelong. Recent clinical studies have trialed latency-reversing agents (LRA) as a method to eliminate latently infected cells; however, the effects of LRA on the central nervous system (CNS), a well-known site of virus persistence on cART, are unknown. In this study, we evaluated the toxicity and potency of a panel of commonly used and well-known LRA (panobinostat, romidepsin, vorinostat, chaetocin, disulfiram, hexamethylene bisacetamide [HMBA], and JQ-1) in primary fetal astrocytes (PFA) as well as monocyte-derived macrophages as a cellular model for brain perivascular macrophages. We show that most LRA are non-toxic in these cells at therapeutic concentrations. Additionally, romidepsin, JQ-1, and panobinostat were the most potent at inducing viral transcription, with greater magnitude observed in PFA. In contrast, vorinostat, chaetocin, disulfiram, and HMBA all demonstrated little or no induction of viral transcription. Together, these data suggest that some LRA could potentially activate transcription in latently infected cells in the CNS. We recommend that future trials of LRA also examine the effects of these agents on the CNS via examination of cerebrospinal fluid.Lachlan R. Gray, Hung On, Emma Roberts, Hao K. Lu, Michael A. Moso, Jacqueline A. Raison, Catherine Papaioannou, Wan-Jung Cheng, Anne M. Ellett, Jonathan C. Jacobson, Damian F.J. Purcell, Steve L. Wesselingh, Paul R. Gorry, Sharon R. Lewin, Melissa J. Churchil
- …
