178,048 research outputs found
Präzise Ionenimplantation mittels Rastermikroskopie
No full textA new technique for precision ion implantation has been developed. A scanning probe has been equipped with a small aperture and incorporated into an ion beamline, so that ions can be implanted through the aperture into a sample. By using a scanning probe the target can be imaged in a non-destructive way prior to implantation and the probe together with the aperture can be placed at the desired location with nanometer precision. In this work first results of a scanning probe integrated into an ion beamline are presented. A placement resolution of about 120 nm is reported. The final placement accuracy is determined by the size of the aperture hole and by the straggle of the implanted ion inside the target material. The limits of this technology are expected to be set by the latter, which is of the order of 10 nm for low energy ions. This research has been carried out in the context of a larger program concerned with the development of quantum computer test structures. For that the placement accuracy needs to be increased and a detector for single ion detection has to be integrated into the setup. Both issues are discussed in this thesis. To achieve single ion detection highly charged ions are used for the implantation, as in addition to their kinetic energy they also deposit their potential energy in the target material, therefore making detection easier. A special ion source for producing these highly charged ions was used and their creation and interactions with solids of are discussed in detail.Eine neue Technik zur Ionenimplantation mit hoher Ortsgenauigkeit wurde entwickelt. Hierzu wurde der Cantilever eines Rasterkraftmikroskops in eine bewegliche Lochmaske umfunktioniert. Die Verwendung eines Rasterkraftmikroskops ermöglicht, die Probe vor der Implantation zu betrachten und die Lochblende mit einer Genauigkeit von einigen Nanometern relativ zu zum Beispiel vorgefertigten Strukturen zu platzieren. In dieser Arbeit werden erste Ergebnisse eines Rasterkraftmikroskops, welches in eine Ionenstrahlführung integrierte wurde, dargestellt. Messungen, die die Auflösungsgrenzen des Mikroskops zeigen, werden präsentiert. Weiterhin werden Ergebnisse mit einer Ionenimplantationsgenauigkeit von 120 nm gezeigt. Eine Grenze für die maximale Auflösung eines solchen Implanters ist durch die Streuung der Ionen beim Abbremsen im Material gegeben. Daher wird die maximale Ortsauflösung, die mit diesem Aufbau erreicht werden kann mit ca. 10 nm abgeschätzt. Die vorliegende Arbeit ist Teil eines Projektes, das sich zum Ziel gesetzt hat, Teststrukturen für Quantencomputer zu erzeugen. Hierzu wird nicht nur eine hohe Ortsauflösung, sondern auch das Implantieren von einzelnen Ionen verlangt. Um dies zu erreichen, muss weiterhin ein Einzelionendetektor in den Aufbau integriert werden. Verschiedene Möglichkeiten hierzu werden ebenfalls in der Arbeit diskutiert. Um das Detektieren einzelner Ionen einfacher zu gestalten werden hochgeladen Ionen benutzt, da diese neben ihrer kinetischen Energie auch potentielle Energie besitzen, die zur Detektion benutzt werden kann. Eine spezielle Ionenquelle zur Erzeugung hochgeladener Ionen ist daher Teil des Aufbaus. Effekte von hochgeladene Ionen und die spezielle Ionenquelle werden daher ebenfalls in der Arbeit diskutiert
Persaud et al. 2024 Geochimica et Cosmochimica Acta
No full textData for: Stability and Structure of Aqueous Sb (III) Chloride Complexes from 25 °C to 250 °C at 25 MPa at High Chloride Ion ConcentrationsAvinaash A. Persaud, Swaroop Sasidharanpillai, Jenny S. Cox, Peter R. TremaineTHIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV
Psychology of optimism [podcast]
No full textIn this podcast Dr Raj Persaud discusses the meaning and underlying psychological constructs of optimism with Dr Rebecca McGuire-Snieckus, author of the paper 'Hope, Optimism and Delusion' published in the Psychiatric Bulletin. By the end of this podcast we hope you will have gained an understanding of: 1) the meaning and underlying constructs of optimism, 2) some of the psychological research on positivity bias, including self enhancing cognitive bias, 3) the relationship between optimism and psychological models of depression, 4)the role of optimism in cognitive behavioural therapy
Population data for Mangrove
No full textRaw population data for 4 species of earthworms found in a sampled mangrove ecosystem
Rainforest Data
No full textdataset represents the raw earthworm population data obtained from Guyana's rainforests in order to investigate the impact of deforestation on earthworm populations
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
CLN3p impacts galactosylceramide transport, raft morphology, and lipid content
No full textJuvenile neuronal ceroid lipofuscinosis (JNCL) belongs to the neuronal ceroid lipofuscinoses characterized by blindness-seizures-motor-cognitive decline and early death. JNCL is caused by CLN3 gene mutations that negatively modulate cell growth-apoptosis. CLN3 protein (CLN3p) localizes to Golgi-Rab4--Rab11-positive endosomes and lipid rafts, and harbors a galactosylceramide (GalCer) lipid raft-binding domain. Goals are proving CLN3p participates in GalCer transport from Golgi to rafts, and GalCer deficits negatively affect cell growth-apoptosis. GalCer-mutant CLN3p are retained in Golgi, with CLN3p rescuing GalCer deficits in rafts. Diminishing GalCer in normal cells by GalCer synthase siRNA negatively affects cell growth-apoptosis. GalCer restores JNCL cell growth. WT CLN3p binds GalCer, but not mutant CLN3p. Sphingolipid content of rafts-Golgi is perturbed with diminished GalCer in rafts and accumulation in Golgi. CLN3-deficient raft vesicular structures are small by transmission electron microscopy, reflecting altered sphingolipid composition of rafts. CLN1-CLN2-CLN6 proteins bind to lysophosphatidic acid-sulfatide, CLN6-CLN8 proteins to GalCer, and CLN8 protein to ceramide. Sphingolipid composition-morphology of CLN1--CLN2--CLN6--CLN8- and CLN9-deficient rafts are altered suggesting changes in raft structure-lipid stoichiometry could be common themes underlying these diseases. Copyright © 2008 International Pediatric Research Foundation, Inc.Boggs JM, 2004, J NEUROSCI RES, V76, P342, DOI 10.1002-jnr.20080; Boustany R.M., 1996, HDB CLIN NEUROLOGY, V22, P671; Brugger B, 2006, P NATL ACAD SCI USA, V103, P2641, DOI 10.1073-pnas.0511136103; Cao Y, 2006, J BIOL CHEM, V281, P20483, DOI 10.1074-jbc.M602180200; de Gassart A, 2003, BLOOD, V102, P4336, DOI 10.1182-blood-2003-03-0871; Dhar S, 2002, ANN NEUROL, V51, P448, DOI 10.1002-ana.10143; Eckford PDW, 2005, BIOCHEM J, V389, P517; Fujita Y, 2000, J NEUROL SCI, V174, P137, DOI 10.1016-S0022-510X(00)00265-3; GAMMON CM, 1987, BIOCHEMISTRY-US, V26, P6239, DOI 10.1021-bi00393a043; Gombos I, 2006, IMMUNOL LETT, V104, P59, DOI 10.1016-j.imlet.2005.11.021; Gottesman MM, 2001, J BIOENERG BIOMEMBR, V33, P453, DOI 10.1023-A:1012866803188; Hanada K, 2003, NATURE, V426, P803, DOI 10.1038-nature02188; Hering H, 2003, J NEUROSCI, V23, P3262; Hirahara Y, 2004, GLIA, V45, P269, DOI 10.1002-glia.10327; Hobert JA, 2007, BIOCHEM BIOPH RES CO, V358, P111, DOI 10.1016-j.bbrc.2007.04.064; Huang Q, 2006, CANCER RES, V66, P5807, DOI 10.1158-0008-5472.CAN-06-0077; JECKEL D, 1992, J CELL BIOL, V117, P259, DOI 10.1083-jcb.117.2.259; Katz ML, 1999, J NEUROSCI RES, V57, P551; Kilkus J, 2003, J NEUROSCI RES, V72, P65, DOI 10.1002-jnr.10549; Kremmidiotis G, 1999, HUM MOL GENET, V8, P523, DOI 10.1093-hmg-8.3.523; LEVINE TP, 2004, TRENDS CELL BIOL, V9, P483; London E, 2000, BBA-BIOMEMBRANES, V1508, P182, DOI 10.1016-S0304-4157(00)00007-1; Luiro K, 2001, HUM MOL GENET, V10, P2123, DOI 10.1093-hmg-10.19.2123; Mahfoud R, 2002, J BIOL CHEM, V277, P11292, DOI 10.1074-jbc.M111679200; Mao QW, 2003, FEBS LETT, V541, P40, DOI 10.1016-S0014-5793(03)00284-9; Margraf LR, 1999, MOL GENET METAB, V66, P283, DOI 10.1006-mgme.1999.2830; Miyaji M, 2005, J EXP MED, V202, P249, DOI 10.1084-jem.20041685; Narayan SB, 2006, ANN NEUROL, V60, P570, DOI 10.1002-ana.20975; Persaud-Sawin DA, 2005, APOPTOSIS, V10, P973, DOI 10.1007-s10495-005-0733-6; Persaud-Sawin DA, 2007, PEDIATR RES, V61, P146, DOI 10.1203-pdr.0b013e31802d8a4a; Persaud-Sawin DA, 2004, PEDIATR RES, V56, P449, DOI 10.1203-01.PDR.0000136152.54638.95; Persaud-Sawin DANW, 2002, HUM MOL GENET, V11, P2129, DOI 10.1093-hmg-11.18.2129; Pullarkat RK, 1997, NEUROPEDIATRICS, V28, P42, DOI 10.1055-s-2007-973665; Rao CS, 2005, BIOPHYS J, V89, P4017, DOI 10.1529-biophysj.105.070631; Rylova SN, 2002, CANCER RES, V62, P801; Sakurai A, 2000, ACTA NEUROPATHOL, V100, P270; Sprong H, 2003, MOL BIOL CELL, V14, P3482, DOI 10.1091-mbc.E03-03-0130; Zaas DW, 2005, BBA-MOL CELL RES, V1746, P305, DOI 10.1016-j.bbamcr.2005.10.00320191
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
CTX DTM and ORI Mosaics over Sakarya Vallis, Gale Crater, Mars
No full textLocal digital terrain model (DTM) and orthorectified image (ORI) mosaics over Sakarya Vallis, west of Aeolis Mons in Gale crater, Mars. The two constituent DTMs were processed using the CASP-GO suite described in Tao et al. (2018); the ORIs were processed using Ames Stereo Pipeline. The DTMs were then co-registered to an HRSC DTM mosaic (Persaud et al. 2021, https://doi.org/10.5281/zenodo.5808354) and each other using Ames Stereo Pipeline, and then cropped and mosaicked.
Format: GeoTiff
Projection: Equidistant cylindrical
Datum: Spheroid (r = 3396.190 km)
Bit depth: Float32
DTM grid-spacing: 18 m/pixel
ORI resolution: 6 m/pixel
Stereo pairs (from Grindrod and Davis, 2018):
P04_002675_1746_XI_05S222W, B21_017786_1746_XN_05S222W
D02_027834_1748_XN_05S222W, G04_019698_1747_XI_05S222W
Image IDs of the ORIs: P04_002675_1746_XI_05S222W, D02_027834_1748_XN_05S222WThe first author is now at Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California. Contact: [email protected]
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