| 1. |
|
|
| 2. |
- Eastham, D. A., et al.
(författare)
-
Construction of a new type of low-energy, scanning electron microscope with atomic resolution
- 2009
-
Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - Monterey : SPIE. - 0277-786X .- 1996-756X. - 9780819476548 ; 7378, s. 73781S-73781S
-
Konferensbidrag (refereegranskat)abstract
- We describe a new type of scanning electron microscope which works by directly imaging the electron field-emission sites on a nanotip. Electrons are extracted from the nanotip through a nanoscale aperture, accelerated in a high electric field and focussed to a spot using a microscale einzel lens. If the whole microscope (accelerating section and lens) and the focal length are both restricted in size to below 10 microns, then computer simulations show that the effects of aberration are extremely small and it is possible to have a system with approximately unit magnification, at electron energies as low as 300 eV. Thus a typical emission site of 1 nm diameter will produce an image of the same size and an atomic emission site with give a resolution of 0.1-0.2 nm (1-2 Å), and because the beam is not allowed to expand beyond 100nm in diameter the depth of field is large and the contribution to the beam spot size from chromatic aberrations is less than 0.02 nm (0.2 Å) for 500 eV electrons. Since it is now entirely possible to make stable atomic sized emitters (nanopyramids) it is expected that this instrument will have atomic resolution. Furthermore the brightness of the beam is determined only by the field-emission and can be up to a million times larger than in a typical (high-energy) electron microscope. The construction of this microscope, based on using a nanotip electron source which is mounted on a nanopositioner so that it can be positioned at the correct point adjacent to the microscope, entrance aperture, is described. In this geometry the scanning is achieved by moving the sample using piezos. Two methods for the construction of the microscope column are reviewed and the results of preliminary tests are described. The advantages of this low energy, bright-beam, electron microscope with atomic resolution are described. It can be used in either scanning mode or diffraction mode. The major advantage over existing microscopes is that because it works at very low energies the elastic backscatteri g is sensitive to the atomic species and so these can be identified directly without any energy discrimination on the detector. Furthermore it is also possible to use the microscope to do low energy electron diffraction which, because the scattering cross-section is large, can be carried out on single molecules. If these are biological samples such as DNA, proteins and viruses then the low energy means that the radiation damage is minimised. Some possibilities for mounting these samples, which can reduce radiation damage, are discussed. Finally we show a system for producing holograms of single protein molecules.
|
|
| 3. |
|
|
| 4. |
- Berghauser Pont, Meta, 1972, et al.
(författare)
-
Quantitative comparison of cities : Distribution of street and building types based on density and centrality measures
- 2017
-
Ingår i: Proceedings - 11th International Space Syntax Symposium, SSS 2017. - : Instituto Superior Tecnico, Departamento de Engenharia Civil, Arquitetura e Georrecursos. - 9789729899447 ; 2, s. 44.1-44.18
-
Konferensbidrag (refereegranskat)abstract
- It has been argued that different urban configurations-planned vs. organic, treelike vs. grid like-perform differently when it comes to the intensity and distribution of pedestrian flows, built density and land uses. However, definitions of urban configurations are often rather abstract, ill-defined and at worse end in fixed stereotypes hiding underlying spatial complexity. Recent publications define morphological typologies based on quantitative variables (e.g. Barthelemy, 2015; Serra, 2013a; Gil et al., 2012; Berghauser Pont and Haupt, 2010) and solve some of these shortcomings. These approaches contribute to the discussion of types in two ways: firstly, they allow for the definition of types based on multiple variables in a precise and repeattable manner, enabling the study of large samples and the comparison between both cities and regions; secondly, they frame design choices in terms of types without being fixed and so open up for design explorations where the relation between the variables can be challenged to propose new types. This paper explores the typologies defined by Serra (2013a) and Berghauser Pont and Haupt (2010) further, as these target two of the most important morphological entities of urban form, namely the street network and the building structure. The purpose is to gain a better understanding of how types are composed and distributed within and across different cities. The method is based on GIS and statistical modeling of four cities to allow for a comparative analysis of four cities: Amsterdam, London, Stockholm and Gothenburg. For the street network, we process the Road-Centre-line maps to obtain a clean network model, then run segment angular analysis to calculate the space syntax measures of betweenness at different metric radii, defining the "centrality palimpsest" (Serra, 2013a). For the building structure, we process elevation data to obtain building height, then run accessible density analysis for all building density metrics (FSI, GSI, OSR, L) using the Place Syntax Tool (Berghauser Pont and Marcus, 2014). The street and building types are defined using cluster analysis (unsupervised classification), following a similar approach to Serra (2013a). The result is a typology of street ('paths') and building types ('places'), with different profiles of centrality and density across scales. The spatial distribution and frequency of these types across the four cities gives an objective summary of their spatial structure, identifying common as well as unique traits.
|
|
| 5. |
- Börjesson, J., et al.
(författare)
-
A method for in-situ electrical measurements of thin film heterostructures using TEM and SEM
- 2008
-
Ingår i: EMC 2008 14th European Microscopy Congress 1–5 September 2008, Aachen, Germany 2008. - Berlin, Heidelberg : Springer. - 9783540852254 - 9783540852261 ; , s. 297-298
-
Konferensbidrag (refereegranskat)abstract
- A method for in-situ measurements of electrical properties of thin film heterostructures using TEM and SEM has been developed. This method allows measurements of the conductance in a thin film heterostructure in a direction along the film planes in thin TEM foils. The advantage is that the properties can be directly correlated to the local atomic structure. The specimens are cross section TEM samples prepared with standard grinding, polishing and ion beam milling techniques
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
- Harvey, P. D., et al.
(författare)
-
Functional Capacity and Functional Disability in Schizophrenia : A Cross-National Study in New York and Sweden
- 2008
-
Konferensbidrag (refereegranskat)abstract
- Background: Functional disability is a central feature of schizophrenia and has been reported to occur across different countries and systems of care. Recent advances in the assessment of disability have separeted the measuremet of functional capacity: the ability to perform skills required for everyday functioning from the measurement of real-world functional outcomes. This presentation reports on a cross-national study of the correlation between functional capacity measured with the UCSD Performance-based Skills Assessment, Brief version (UPSA-B), casemanager ratings of patient everyday functioning with the Specific Levels Of Functioning (SLOF), and occurrence of real-world functional milestones, including independent living, employment, and marital status. Patients with schizophrenia who lived in an urban American setting and a generally rural region in Sweden were compared on their functional capacity performance and real-world outcomes. Metods:Samples of schizophrenia patients in Sweden (n=146) and New York (n=244) performed the UPSA-B and a neuropsychological assessment and were rated by their case managers. Information from archival records and case managers was used to determine the occurence of the different real world outcomes, including living independently and having ever experienced a stable romantic relationship.Results: Performance on the UPSA-B was essentially identical in the two patient samples, with a total raw score in the New York sample 13.8 and the score in the Swedish sample 13.8. Scores on the case manager ratings of everyday activities were also strikingly similar (New York:49; Sweden:49). Further, the correlation between UPSA-B scores and ratings of everyday activities were quite similar, New York: r=.36 Sweden: r=.27 as were the correlations between NP performance and UPSA-B scores, New York: r=.58; Sweden: r=.55. Also, the proportion of cases who had never been married or had a close relationship was 59% in New York and 64% in Sweden. In notable contrast, 80% of the Swedish patients and 46% of the New York patients were living independently.Implications: Performance-based measures of functional capacity were very similar across samples of people with schizophrenia in very different living environments. These results are consistent with previous studies showing that performance-based measures of cognition are also quite similar across different countries in people with schizophrenia. While measures of functional ability and case manager estimates of patients' real-world outcomes were very similar in level of impairment and correlational structure, real-world residential outcomes were very different. These data suggest that cultural and social support systems can lead to very divergent outcomes in individuals who have evidence of the same levels of ability and potential.
|
|
| 10. |
- Harvey, P.D, et al.
(författare)
-
Performance-based measurement of functional disability in schizophrenia: a cross-national study in the United States and Sweden
- 2009
-
Ingår i: American Journal of Psychiatry. - : American Psychiatric Association Publishing. - 0002-953X .- 1535-7228. ; :166, s. 821-827
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Recent advances in the assessment of disability in schizophrenia have separated the measurement of functional capacity from real-world functional outcomes. The authors examined the similarity of performance-based assessments of everyday functioning, real-world disability, and achievement of milestones in people with schizophrenia in the United States and Sweden. METHOD: The UCSD Performance-Based Skills Assessment-Brief Version (UPSA-B) and a neuropsychological assessment were administered to schizophrenia patients living in rural areas in Sweden (N=146) and in the New York City area (N=244), and patients' functioning was rated by their case managers. Information from records and case managers was used to determine the frequency of living independently, working, and having ever experienced a stable romantic relationship. RESULTS: Performance on the UPSA-B was essentially identical in the two samples (New York, mean score=13.84; Sweden, mean score=13.30), as were scores on the case manager ratings of everyday activities (New York, mean=49.0; Sweden, mean=48.8). The correlations between UPSA-B score, neuropsychological test performance, and case manager ratings did not differ across the two samples. The proportion of patients who had never had a close relationship and the rate of vocational disability were also nearly identical. However, while 80% of the Swedish patients were living independently, only 46% of the New York patients were. CONCLUSIONS: While scores on performance-based measures of everyday living skills were similar in people with schizophrenia across cultures, real-world residential outcomes were very different. These data suggest that cultural and social support systems can lead to divergent real-world outcomes among individuals who show evidence of the same levels of ability and potential.
|
|
