| 1. |
- Fuzzi, S., et al.
(författare)
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The Po Valley Fog Experiment 1989
- 1992
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Ingår i: Tellus. Series B: Chemical and Physical Meteorology. - : Stockholm University Press. - 0280-6509. ; 44:5, s. 448-468
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Tidskriftsartikel (refereegranskat)abstract
- An outline is presented here of the Po Valley Fog Experiment 1989, carried out within the EUROTRAC‐GCE project. This experiment is a joint effort by several European research groups from 5 countries. The physical and chemical behaviour of the fog multiphase system was studied experimentally following the temporal evolution of the relevant chemical species in the different phases (gas, droplet, interstitial aerosol) and the evolution of micrometeorological and microphysical conditions, from the pre‐fog situation through the whole fog evolution, to the post‐fog period. Some general results, useful for describing the general features of the fog system, are presented here, while specific scientific questions on the different processes taking place within the system itself will be addressed in other companion papers of this same issue.
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| 2. |
- Kaigle Holm, Allison, 1964, et al.
(författare)
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A method for the intravital measurement of interspinous kinematics.
- 1992
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Ingår i: Journal of biomechanics. - 0021-9290. ; 25:4, s. 451-6
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Tidskriftsartikel (refereegranskat)abstract
- A novel non-radiographic technique for objectively quantifying quasi-static or dynamic intervertebral motion of a spinal motion segment in vivo in human subjects is presented here. The intervertebral motion device (IMD) is an instrumented linkage transducer system which can continuously measure over time two-dimensional sagittal plane rigid-body motion. Three custom-built omega-shaped displacement transducers are utilized. The IMD is rigidly fixed to the spinous processes of the lumbar motion segment by means of two intraosseous pins. Knowing the mechanoelectrical behavior and geometric configuration of the IMD, the relative spatial motion between the vertebral bodies can be resolved into sagittal rotation, axial translation, and anterior-posterior shear translation. Static calibrations of the IMD in the ranges of +/- 4 degrees rotation and +/- 4 mm translation determined the absolute maximum errors to be 0.2 degree and 0.07 mm for rotation and translation measurements, respectively, with corresponding variances of 0.1 degrees and 0.03 mm. For use in the vibration environment, negligible motion artifact content was detected in the IMD output signals when excited at discrete frequencies of 5.0 and 8.0 Hz. The first natural frequency of the IMD, specific for this design, was measured at 16.25 Hz. This technique may be used to study in vivo the spinal kinematics in healthy lumbar motion segments and in patients suspected of having segmental instability, and can perhaps be of clinical diagnostic significance.
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| 3. |
- Wiman, Bo, et al.
(författare)
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Perspectives on Aerosol Deposition to Natural Surfaces: interactions between aerosol residence times, removal processes, the biosphere and global environmental change
- 1990
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Ingår i: Journal of Aerosol Science. - 0021-8502 .- 1879-1964. ; 21:3, s. 313-338
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Tidskriftsartikel (refereegranskat)abstract
- This paper summarizes the state-of-the-art and the research needs in the areas of aerosol residence-time assessments, deposition modelling, and understanding of aerosols in biogeochemistry. Research needs are emphasized from a systems perspective of global environmental change. Although fundamental quantitative knowledge is lacking, some qualitative linkages between source strengths, residence times, removal processes and the biosphere can be identified. It turns out that not only are the respective areas as such challenged by new problems, superimposed on the fairly well established conventional ones, but these areas also face mutually operating sets of feedbacks between residence times and sink/source characteristics of ecological systems subject to stress. To evaluate the sensitivity of these feedback loops, and to assess whether they are negative (stabilizing interactions) or positive (destabilizing) are important and potentially urgent tasks. Such studies should focus on a common goal, such as developing empirical and theoretical understanding of aerosol resuspension, transport and deposition for application in large-scale circulation models. A basic link in such advancements is that structural change of vegetated surfaces of the biosphere caused by deposition itself, and by changing land-use and climate, be understood and assessed. This article was initiated in connection with the Workshop on Aerosol Deposition to Natural Surfaces, Lund, Sweden, 2 September, 1988; conducted during the European Aerosol Conference (see J. Aerosol Sci. 19, 775–776). The authors wish to express their thanks to the workshop participants (list available from the workshop coordinators).
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| 4. |
- Brabant, G, et al.
(författare)
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E-cadherin: a differentiation marker in thyroid malignancies.
- 1993
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Ingår i: Cancer research. - 0008-5472. ; 53:20, s. 4987-93
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Tidskriftsartikel (refereegranskat)abstract
- Loss of E-cadherin (uvomorulin), a Ca(2+)-dependent cell adhesion molecule required for normal epithelial function, has been attributed a pathogenetic role in tumor invasion. The expression of E-cadherin was studied in normal and neoplastic follicular epithelium of the human thyroid by Northern blot analysis and immunofluorescence on frozen tissue sections. In the normal thyroid (n = 10) and in benign thyroid disorders (n = 21; toxic diffuse goitre; multinodular goitre; follicular adenomas), E-cadherin mRNA levels were equally high and the follicles were generally stained, mainly along the lateral surface of the epithelial cells, by the anti-E-cadherin monoclonal antibody. In anaplastic thyroid carcinomas (n = 6) E-cadherin expression was very low or lacking. In papillary carcinomas (n = 23), E-cadherin mRNA levels varied from nearly normal to highly reduced, which roughly correlated with the overall immunofluorescence intensity. However, the immunostaining also revealed a heterogeneous "all-or-nothing" expression of E-cadherin among adjacent cells in the same tumor. In the follicular carcinomas (n = 9), E-cadherin mRNA levels were in general rather high but the immunostaining varied considerably. A few papillary and follicular tumors lacked immunoreactive E-cadherin in spite of high mRNA levels. In oxyphilic (Hürthle) cell tumors, comprising both adenomas (n = 4) and carcinomas (n = 2), E-cadherin immunoreactivity was reduced and distributed intracellularly rather than at the cell surface. The expression of E-cadherin in relapsing thyroid carcinomas and in tumors with metastatic spreading was, irrespective of the histiotype, low or lacking. Sequential Northern analysis revealed a close correlation between the expression levels of E-cadherin and the thyrotropin receptor. Together, the data suggest that in human thyroid malignancies both gene expression and posttranscriptional control of E-cadherin may be impaired.
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| 5. |
- Olevik, David, et al.
(författare)
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Critique of an experiment regarding quantum states in a gravitational field and possible geometrical explanations
- 1992
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- We discuss an experiment conducted by Nesvizhevsky et al. As it is the first experiment claimed to have observed gravitational quantum states, it is imperative to investigate all alternative explanations of the result. In a student project course in applied quantum mechanics, we consider the possibility of quantummechanical effects arising from the geometry of the experimental setup, due to the "cavity" formed. We try to reproduce the experimental result using geometrical arguments only. Due to the influence of several unknown parameters our result is still inconclusive.
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| 6. |
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| 7. |
- Wiedensohler, A., et al.
(författare)
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A novel unipolar charger for ultrafine aerosol particles with minimal particle losses
- 1994
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Ingår i: Journal of Aerosol Science. - : Elsevier BV. - 0021-8502. ; 25:4, s. 639-649
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Tidskriftsartikel (refereegranskat)abstract
- A unipolar diffusion charger with minimal particle losses in the ultrafine size range has been developed. This charger uses two radioactive α-sources to produce ions which are drawn into the charging region by an alternating electric field. The aerosol flow in the centre of the charging region is surrounded by a particle-free sheath air flow to prevent particle losses. Charged aerosol particles move in a "zigzag" manner in the charging channel under the influence of the alternating electric field. Positive gas ions, with higher electrical mobilities than ultrafine aerosol particles, homogeneously fill the entire charging region. Here, the aerosol becomes unipolarly charged. The charging efficiency is strongly dependent on the residence time of the particles in the ion cloud. The ion current was measured in the charging region to determine the ion concentration. The residence time of the particles in the ion cloud was calculated for each stream line of the aerosol flow. The losses of ultrafine particles in the charger were experimentally determined. The unipolar charge distribution was measured and calculated by integrating the theoretical charge distribution over all stream lines of the aerosol flow.
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