Physics And Astronomy (12)
MRS Online Proceedings Library Archive (6)
The Journal of Asian Studies (4)
International Organization (2)
International Psychogeriatrics (2)
Seed Science Research (2)
Antarctic Science (1)
CNS Spectrums (1)
Health Economics, Policy and Law (1)
Journal of Helminthology (1)
Law and History Review (1)
Proceedings of the British Society of Animal Science (1)
The Association for Asian Studies (4)
International Psychogeriatric Association (2)
American Society for Legal History (1)
International Astronomical Union (1)
Neuroscience Education Institute (1)
Impulsivity and decision-making in obsessive-compulsive disorder after effective deep brain stimulation or treatment as usual
Giacomo Grassi, Martijn Figee, Pieter Ooms, Lorenzo Righi, Takashi Nakamae, Stefano Pallanti, Rick Schuurman, Damiaan Denys
Journal: CNS Spectrums / Volume 23 / Issue 5 / October 2018
Impulsivity and impaired decision-making have been proposed as obsessive-compulsive disorder (OCD) endophenotypes, running in OCD and their healthy relatives independently of symptom severity and medication status. Deep brain stimulation (DBS) targeting the ventral limb of the internal capsule (vALIC) and the nucleus accumbens (Nacc) is an effective treatment strategy for treatment-refractory OCD. The effectiveness of vALIC-DBS for OCD has been linked to its effects on a frontostriatal network that is also implicated in reward, impulse control, and decision-making. While vALIC-DBS has been shown to restore reward dysfunction in OCD patients, little is known about the effects of vALIC-DBS on impulsivity and decision-making. The aim of the study was to compare cognitive impulsivity and decision-making between OCD patients undergoing effective vALIC-DBS or treatment as usual (TAU), and healthy controls.
We used decision-making performances under ambiguity on the Iowa Gambling Task and reflection impulsivity on the Beads Task to compare 20 OCD patients effectively treated with vALIC-DBS, 40 matched OCD patients undergoing effective TAU (medication and/or cognitive behavioural therapy), and 40 healthy subjects. Effective treatment was defined as at least 35% improvement of OCD symptoms.
OCD patients, irrespective of treatment modality (DBS or TAU), showed increased reflection impulsivity and impaired decision-making compared to healthy controls. No differences were observed between OCD patients treated with DBS or TAU.
OCD patients effectively treated with vALIC-DBS or TAU display increased reflection impulsivity and impaired decision-making independent of the type of treatment.
Effects of social behaviour on patch utilization by sheep in a complex vegetation mosaic
A. M. Sibbald, S. P. Oom, R. J. Hooper, R. Anderson
Journal: Proceedings of the British Society of Animal Science / Volume 2005 / 2005
Published online by Cambridge University Press: 23 November 2017, p. 63
In heterogeneous environments, such as complex vegetation mosaics, there is likely to be a dynamic interaction between the spatial pattern of the vegetation and the distribution of the animals grazing there. Preferences for particular vegetation types will influence where animals choose to feed and, in turn, changes to the vegetation caused by damage from grazing and trampling will affect the dynamics of the mosaic. Social interactions, amongst highly social grazers such as sheep, can also affect the distribution of the animals, depending on the relationship between the dimensions of vegetation patches and the characteristic spacing of the animals. The aim of this study was to investigate the relationship between patch utilization and patch size for small groups of Scottish Blackface sheep foraging in a natural heather (Calluna vulgaris ) and grass mosaic.
Towards a coherent global framework for health financing: recommendations and recent developments
Trygve Ottersen, Riku Elovainio, David B. Evans, David McCoy, Di Mcintyre, Filip Meheus, Suerie Moon, Gorik Ooms, John-Arne Røttingen
Journal: Health Economics, Policy and Law / Volume 12 / Issue 2 / April 2017
The articles in this special issue have demonstrated how unprecedented transitions have come with both challenges and opportunities for health financing. Against the background of these challenges and opportunities, the Working Group on Health Financing at the Chatham House Centre on Global Health Security laid out, in 2014, a set of policy responses encapsulated in 20 recommendations for how to make progress towards a coherent global framework for health financing. These recommendations pertain to domestic financing of national health systems, global public goods for health, external financing for national health systems and the cross-cutting issues of accountability and agreement on a new global framework. Since the Working Group concluded its work, multiple events have reinforced the group's recommendations. Among these are the agreement on the Addis Ababa Action Agenda, the adoption of the Sustainable Development Goals, the outbreak of Ebola in West Africa and the release of the Panama Papers. These events also represent new stepping stones towards a new global framework.
8. Commission de l'Astronomie Méridienne
Frank Dyson, MM. Aiginitis, Armellini, Bemporad, Boss, Camera, de Sitter, Dneprovsky, Dodwell, Fayet, Gonnessiat, Gyllenberg, Hins, Jackson, Jeffers, Jones, Kopff, A. Lambert, Moreau, Morgan, Oom, Perrine, Stewart, Zimmer
Journal: Transactions of the International Astronomical Union / Volume 4 / 1933
Since the last meeting of the International Astronomical Union, much attention has been given both in Germany and America to the systematic errors of the fundamental catalogues of Boss and Auwers. This is of special importance if the proper motions of any of the stars are to be used in the verification of the rotation in the plane of the Milky Way. The periodic errors in the proper motions, both in right ascension and declination, are of significance in this connection, while the motion of the equinox is required for the determination of precession, and the systematic correction to the proper motions of declination affects the position of the Solar Apex and the Vertices of the Star Streams.
Experimental and theoretical study of dewetting corner flow
Hyoungsoo Kim, Christian Poelma, Gijs Ooms, Jerry Westerweel
Journal: Journal of Fluid Mechanics / Volume 762 / 10 January 2015
Print publication: 10 January 2015
We study a partial dewetting corner flow with a moving contact line at a finite Reynolds number, $0<\mathit{Re}<O(100)$ . When the speed of the moving contact line increases, the receding contact line appears with a corner shape that is also observed in a gravity-driven liquid droplet on an incline and on a plate withdrawn from a bath. In the current problem, $\mathit{Re}\,{\it\epsilon}$ is larger than unity, where ${\it\epsilon}$ is the aspect ratio of the flow structure. Therefore, classical lubrication theory is no longer appropriate. We develop a modified three-dimensional lubrication model for the dewetting corner structure at $\mathit{Re}\,{\it\epsilon}>1$ by taking into account the internal flow pattern and by scaling arguments. The key requirement is that the streamlines in the corner are straight and (nearly) parallel. In this case, we can obtain a modified pressure consisting of the capillary pressure and the dynamic pressure. This model describes the three-dimensional dewetting corner structure at the rear of the moving droplets at $\mathit{Re}\,{\it\epsilon}>1$ and furthermore shows that the dynamic pressure effects become dominant at a small half-opening angle. Additionally, this model provides analytical results for the internal flow, which is a self-similar flow pattern. To validate the analytical results, we perform high-speed shadowgraphy and tomographic particle image velocimetry (PIV). We find a good agreement between the theoretical and the experimental results.
10 - The Struggle againstHIV/AIDS
from Part II - Synergies and Conflicts in Different Goals
By Gorik Ooms, Rachel Hammonds, Gregg Gonsalves
Edited by Malcolm Langford, Universitetet i Oslo, Andy Sumner, King's College London, Alicia Ely Yamin, Harvard University, Massachusetts
Book: The Millennium Development Goals and Human Rights
Published online: 05 October 2013
John Owen Haley, The Spirit of Japanese Law, Athens: The University of Georgia Press, 1998. Pp. xx + 251. $50.00 (ISBN 0-8203-2022-6).
Herman Ooms
Journal: Law and History Review / Volume 19 / Issue 2 / Summer 2001
Print publication: Summer 2001
A Holocene palaeoenviromental study of a sediment core from Ile de la Possession, Iles Crozet, sub-Antarctica
Marijke Ooms, Bart van de Vijver, Stijn Temmerman, Louis Beyens
Journal: Antarctic Science / Volume 23 / Issue 5 / October 2011
Ile de la Possession is one of the few islands in the southern Indian Ocean, making the island a valuable place to reconstruct past environmental and climatic changes. In this study a peat sediment core was analysed to reconstruct the changes that occurred before, during and after the eruption of the Morne Rouge (10 000–5500 14C yr bp) volcano. In addition to sedimentological analyses, diatom communities were used to reconstruct humidity and altitude, based on existing transfer functions. Radiocarbon dating of a tephra layer showed that the Morne Rouge volcano erupted between 6700–6600 cal. yr bp, giving a much more precise time scale for this event. The eruption was preceded by a tsunami flooding, indicated by the high numbers of marine diatoms found immediately before the tephra layer. After the eruption pioneer diatom species recolonized the coring site. Evidence is presented of the late climatic optimum around 3050 cal. yr bp, preceded by a cooling event until 6600 cal. yr bp. Nutrient input from elephant seals and wandering albatrosses obscured the climate signal for the last 600 cal yr bp.
Ageing of Eurobitum Bituminised Radioactive Waste under Gamma Irradiation
Fabian Rorif, Elie Valcke, Patrick Boven, Hans Ooms, Jozef Peeters, Steven Smets
Journal: MRS Online Proceedings Library Archive / Volume 932 / 2006
Published online by Cambridge University Press: 21 March 2011, 47.1
The extent of the physico-chemical processes of concern in the study on the acceptability of the Belgian Eurobitum bituminised waste for underground disposal will depend on the degree ofageing of the bituminous matrix. Therefore, the ageing of non-radioactive simulates of Eurobitum under gamma irradiation was studied both in the presence and absence of oxygen. Chemical changes in the bitumen structure were measured in the mid-infrared region with the attenuated total reflectance infrared technique (ATR/FTIR) and evaluation of the peaks at 1700 cm−1 (C=O) and 1600 cm−1 (C=C). Even for the highest total absorbed doses (∼800 kGy at ∼150 Gy/h), the effect of the irradiation in Eurobitum was found to be small and was, in any case, smaller than for samples heated for three hours at 130°C in air.
Magnetic Measurements on YBa(2)Cu(3)O(x) Ceramic High Temperature Superconductors
J. Cornelis, A. Van Den Bosch, J. Vansummeren, H. Ooms, R. Gilissen, J. Cooymans, N. Maene, F. Biermans
Journal: MRS Online Proceedings Library Archive / Volume 99 / 1987
Published online by Cambridge University Press: 28 February 2011, 829
Static magnetic susceptibilities have been measured, following the Faraday method, on a disc of home-made YBa(2)Cu(3)O(x). The superconducting ceramic disc was oriented perpendicular to the applied magnetic induction field < 10 mT. On cooling the sample in a constant field from above to below the critical temperature a Meissner-Ochsenfeld effect is observed. The interpretation of the data yields partial flux expulsion. That the flux is not completely expelled from the sample is understood on the basis of the flatness of the disc. Part of the flux which had not been expelled by the Meissner-Ochsenfeld effect remains trapped in the cooled superconducting material.
Properties of Epitaxial SrTiO3 Thin Films Grown on Silicon by Molecular Beam Epitaxy
Z. Yu, R. Droopad, J. Ramdani, J.A. Curless, C.D. Overgaard, J.M. Finder, K.W. Eisenbeiser, J. Wang, J.A. Hallmark, W.J. Ooms
Single crystalline perovskite oxides such as SrTiO3 (STO) are highly desirable for future generation ULSI applications. Over the past three decades, development of crystalline oxides on silicon has been a great technological challenge as an amorphous silicon oxide layer forms readily on the Si surface when exposed to oxygen preventing the intended oxide heteroepitaxy on Si substrate. Recently, we have successfully grown epitaxial STO thin films on Si(001) surface by using molecular beam epitaxy (MBE) method. Properties of the STO films on Si have been characterized using a variety of techniques including in-situ reflection high energy electron diffraction (RHEED), ex-situ X-ray diffraction (XRD), spectroscopic ellipsometry (SE), Auger electron spectroscopy (AES) and atomic force microscopy (AFM). The STO films grown on Si(001) substrate show bright and streaky RHEED patterns indicating coherent two-dimensional epitaxial oxide film growth with its unit cell rotated 450 with respect to the underlying Si unit cell. RHEED and XRD data confirm the single crystalline nature and (001) orientation of the STO films. An X-ray pole figure indicates the in-plane orientation relationship as STO[100]//Si[110] and STO(001)// Si(001). The STO surface is atomically smooth with AFM rms roughness of 1.2 AÅ. The leakage current density is measured to be in the low 10−9 A/cm2 range at 1 V, after a brief post-growth anneal in O2. An interface state density Dit = 4.6 × 1011 eV−1 cm−2 is inferred from the high-frequency and quasi-static C-V characteristics. The effective oxide thickness for a 200 Å STO film is around 30 Å and is not sensitive to post-growth anneal in O2 at 500-700°C. These STO films are also robust against forming gas anneal. Finally, STO MOSFET structures have been fabricated and tested. An extrinsic carrier mobility value of 66 cm2 V−11 s−1 is obtained for an STO PMOS device with a 2 μm effective gate length.
Epitaxial Oxide Films on Silicon: Growth, Modeling and Device Properties
R. Droopad, J. Wang, K. Eisenbeiser, Z. Yu, J. Ramdani, J. A. Curless, C. D. Overgaard, J. M. Finder, J. A. Hallmark, V. Kaushik, B. Y. Nguyen, D. S. Marshall, W. J. Ooms
Using molecular beam epitaxy, thin films perovskite-type oxide SrxBa1−xTiO3 (0≤×≤1) has been grown epitaxially on Si(001) substrates. Reflection high energy electron diffraction measurements and X-ray diffraction analysis indicate that high quality heteroepitaxy on Si takes place with SrxBa1−xTiO3(001)//Si(001) and SrxBa1−xTiO3[010]//Si[10]. Extensive atomic simulations have been carried out to understand the initial growth mechanism of the oxide layers on silicon. SrTiO3 layers grown directly on Si have been used as the gate dielectric for the fabrication of MOSFET devices. By varying the growth conditions the thickness of the amorphous interfacial silicon oxide layer formed during the growth of the oxide layers has been engineered to minimize the device short channel effects. An effective oxide thickness <10 Å has been obtained for a 110 Å thick SrTiO3 dielectric film with interface state density around 6.4 × 1010 cm−2 eV-1, and the inversion layer carrier mobilities of 220 cm2 V−1 s−1 and 62 cm 2 V−ls−1 for NMOS and PMOS devices, respectively. The gate leakage in these devices is 2 orders of magnitude smaller than a comparable SiO2 gate dielectric MOSFET.
Sr/Si Template Formation for the Epitaxial Growth of SrTiO3 on Silicon
Xiaoming Hu, Y. Liang, Yi Wei, J.L. Edwards, R. Droopad, K. Moore, W.J. Ooms
Published online by Cambridge University Press: 01 February 2011, B6.2
A novel silicon cleaning process using strontium metal thin films has been described. The silicon dioxide de-oxidation process using strontium as catalysts has been studied by X-ray Photoelectron Spectroscopy (XPS) and other in-situ techniques. A Sr/Si template for the epitaxial growth of SrTiO3 single crystals on silicon can be directly formed as a result of the above Sr-de-oxidation process. The de-oxidation mechanism can be explained after solving the interfacial structures of the Sr/SiO2/Si system with in-situ XPS.
Si(100) Surface Cleaning Using Sr and SrO
Yi Wei, Xiaoming Hu, Yong Liang, D.C. Jordan, Brad Craigo, Ravi Droopad, Z. Yu, Alex Demkov, John L. Edwards, Karen Moore, William J. Ooms
A method for removing SiO2 and producing an ordered Si(100) surface using Sr or SrO has been developed. In this technique, a few monolayers of Sr or SrO are deposited onto the as received Si(100) wafer in a ultrahigh vacuum molecular beam epitaxy system. The substrate is then heated to ∼800°C for about 5 minutes, the SiO2 is removed to leave behind a Sr terminated Si(100) surface. This Sr terminated Si(100) surface is well suited for the growth of crystalline high k dielectric SrTiO3 films. Temperature programmed desorption measurements were carried out to understand the mechanism of removing SiO2 from Si(100) using Sr or SrO. The species we observed coming off the surface during the temperature cycle was mainly SiO and O, no significant amount of Sr containing species was observed. We conclude that the SiO2 removal is due to the catalyst reaction SiO2 + Sr (or SrO) → SiO (g) + O + Sr (or SrO). The reaction happened through several intermediate steps. The reaction SiO2 + Si → 2SiO (g) at the SiO2/Si interface is limited and the pit formation is suppressed. The main roles that Sr or SrO play during the oxide removal process are catalysts promoting SiO formation and preventing further etching and the formation of pits in the substrate.
Flow of a viscous compressible fluid produced in a circular tube by an impulsive point source
B. U. FELDERHOF, G. OOMS
Journal: Journal of Fluid Mechanics / Volume 668 / 10 February 2011
Print publication: 10 February 2011
The flow of a viscous compressible fluid in a circular tube generated by a sudden impulse at a point on the axis is studied on the basis of the linearized Navier–Stokes equations. A no-slip boundary condition is assumed to hold on the wall of the tube. An efficient numerical scheme has been developed for the calculation of flow velocity and pressure disturbance as a function of position and time.
Direct numerical simulation analysis of local flow topology in a particle-laden turbulent channel flow
M. J. BIJLARD, R. V. A. OLIEMANS, L. M. PORTELA, G. OOMS
Journal: Journal of Fluid Mechanics / Volume 653 / 25 June 2010
Published online by Cambridge University Press: 02 June 2010, pp. 35-56
Print publication: 25 June 2010
The results of point-particle Eulerian–Lagrangian direct numerical simulation (DNS) calculations of dilute particle-laden turbulent channel flow are used to study the effect of the particles on the local flow topology. It is found that in the viscous sublayer, the flow becomes increasingly more two-dimensional as the two-way coupling effect (due to interaction between particles and fluid flow) increases with increasing particle load. Beyond the viscous sublayer the modifications in flow topology are not strongly related to the preferential concentration of particles in the flow field, which is in contrast to previous channel flow simulations. The effect of particles on the turbulent flow beyond the viscous sublayer is mostly a result of the overall changing near-wall dynamics of the fluid flow.
The Multinational Enterprise and World Political Economy
Robert O. Keohane, Van Doorn Ooms
Journal: International Organization / Volume 26 / Issue 1 / Winter 1972
Published online by Cambridge University Press: 22 May 2009, pp. 84-120
Print publication: Winter 1972
The multinational firm and international regulation
Robert O. Keohane, Van Doom Ooms
Writing about alternative international regimes to deal with direct foreign investment (DFI) may seem to be somewhat like discussing a perpetual motion machine: most people would like one for their own purposes; no one has ever built one; and discussions about their construction often take on a certain air of unreality. In contrast to the issue areas of money, trade, and aid, there is no important set of international institutions concentrating primarily on DFI. Numerous bilateral agreements and multilateral arrangements regulate or facilitate, in one way or another, the activities of private investors, but these have not been systematized into a coherent structure. Negotiations for new agreements do not take place within a large and semiformal international arrangement, such as the General Agreement on Tariffs and Trade (GATT), and no large international institution, such as the World Bank in the aid field, exists primarily to give direction to activities in this area.
Particle–fluid interactions in grid-generated turbulence
C. POELMA, J. WESTERWEEL, G. OOMS
Journal: Journal of Fluid Mechanics / Volume 589 / 25 October 2007
Print publication: 25 October 2007
The effect of small particles on decaying grid-generated turbulence is studied experimentally. Using a two-camera system, instantaneous fluid-phase and particle-phase measurements can be obtained simultaneously. The data obtained with this system are used to study the decay behaviour of the turbulent flow. The role of particle size, particle density and volume load is studied in a number of different cases. These cases are chosen so that the individual role of these parameters can systematically be evaluated. Addition of particles to the flow has significant effects on the decaying turbulence: first, the onset of the turbulent decay appears to shift upstream; second, the flow becomes anisotropic as it develops downstream. The latter is observed as an increase in integral length scale in the vertical direction. The rate at which the flow becomes anisotropic can be predicted using a new parameter: the product of the non-dimensional number density and the Stokes number (referred to as the 'Stokes load'). This parameter, combining the relevant fluid and particle characteristics, is a measure for the energy redistribution leading to anisotropy. In addition to redistributing energy, the particles also produce turbulence. However, this only becomes evident when the grid-generated turbulence has decayed sufficiently, relatively far downstream of the grid. The turbulence production by particles can also account for the observed decrease in slope of the power spectrum, which leads to a 'cross-over' effect. The production of turbulence by the particles can be predicted using a model for the momentum deficit of the particle wakes. The validity of this approach is confirmed using conditional sampling of the fluid velocity field around the particles.
Interaction and collisions between particles in a linear shear flow near a wall at low Reynolds number
PIETRO POESIO, GIJS OOMS, ANDREAS TEN CATE, JULIAN C. R. HUNT
Journal: Journal of Fluid Mechanics / Volume 555 / 25 May 2006
Print publication: 25 May 2006
The flow field around pairs of small particles moving and rotating in a shear flow close to a wall at low but finite Reynolds number (Re) is computed as a function of time by means of the lattice-Boltzmann technique. The total force and torque acting on each particle is computed at each time step and the position of the particles is updated. By considering the lift force and the disturbances induced by the particles, the trajectories of the pair of particles are explained as a function of the distances from the wall and the Reynolds number. It is shown that when particles are positioned in a particular form, they collide forming strings. In particular, we are interested in particle-bridge formation in shear flows, and two collided particles (a string) can be considered as a nucleus of a particle bridge.