A Monte Carlo investigation of the dual photopeak window scattercorrection method [SPECT]

Results from a Monte Carlo investigation of the dual photopeak window (DPW) scatter correction method are presented for point and extended sources of Tc-99m in both homogeneous and nonhomogeneous attenuating media. The DPW method uses the ratio of counts in two nonoverlapping energy windows within the photopeak region as input to a regression relation. A pixel-by-pixel estimate of the scatter in the summed windows is obtained and subtracted to yield an estimate of the primary. An approximate tenfold decrease in the scatter fraction and an excellent agreement with the shape of the true scatter distribution were observed     

Rethinking competence systems for knowledge-based organizations

Existing competence systems are based on a rationalistic view of competence. While these competence systems might work in job-based organizations, we argue that in more dynamic settings, such as in knowledge-based organizations, the interest-informed actions that capture the emergent competencies of tomorrow require different types of information technology support. The main objective of this paper is to elaborate on the possibilities and implications of using interest-activated technology as a design rationale for competence systems. This paper is based on an action case study of an implemented interest-activated Intranet recommender system prototype at Volvo Information Technology AB in Gothenburg, Sweden. On the basis of how organizational members used this prototype to find information they were interested in, our research team was able to inquire into how personal interest, embodied in information-seeking activities, could be a means for identifying competence. Building on the relation between personal interest and competence, we discuss competence systems design and spell out explicit implications for managerial practice in knowledge-based organizations.     

Pleiotropic,Unique and Shared Responses Elicited by IL-6 Family Cytokines in Human Vascular Endothelial Cells

Vascular endothelial cells express glycoprotein 130 (gp130), which is utilized as a signaling receptor by cytokines in the interleukin-6 (IL-6) family. Several IL-6 family cytokines can be found in the circulatory system during physiological or pathological conditions, and may influence endothelial function and response. This study evaluated and compared the cellular and molecular responses induced by IL-6 family cytokines in human endothelial cells. A proteomic analysis showed that IL-6 family cytokines induce the release of a range of proteins from endothelial cells, such as C-C motif chemokine ligand 23, hepatocyte growth factor, and IL-6. Pathway analysis indicated that gp130-signaling in endothelial cells regulates several functions related to angiogenesis and immune cell recruitment. The present investigation also disclosed differences and similarities between different IL-6 family cytokines in their ability to induce protein release and regulate gene expression and intracellular signaling, in regards to which oncostatin M showed the most pronounced effect. Further, this study showed that soluble gp130 preferentially blocks trans-signaling-induced responses, but does not affect responses induced by classic signaling. In conclusion, IL-6 family cytokines induce both specific and overlapping molecular responses in endothelial cells, and regulate genes and proteins involved in angiogenesis and immune cell recruitment.     

Open source movements as a model for organising

Open source software such as the operating system Linux has in a few years created much attention as an alternative way to develop and distribute software. Open source is to let anyone have access to the source code, so that they can modify it. Open source can be seen as a movement, where communities of highly skilled programmers collectively develop software, often of a quality that outperforms commercial proprietary software. These movements are based on virtual networking on the Internet and the web. They are loosely coupled communities kept together by strong common values related to hacker culture. Work seems to be totally distributed, delegated and loosely coupled. The highly skilled members contribute to the collective effort of free software development. In this paper the open source phenomenon is investigated from different perspectives. It is claimed that the open source movement is one key to the understanding of future forms of organizations, information work and business.     

The power of gifts: organizing social relationships in open source communities

Abstract. In writings on the open source software development model, it is often argued that it is successful as a result of the gift economy that embraces activities in online communities. However, the theoretical foundations for this argument are seldom discussed and empirically tested. Starting with the 'classic' theories of gift giving, we discuss how they need to be developed in order to explain gift-giving practices in digital domains. In this paper, we argue that the gift economy is important, not only because it creates openness, but also because it organizes relationships between people in a certain way. Open source software development relies on gift giving as a way of getting new ideas and prototypes out into circulation. This also implies that the giver gets power from giving away. This power is used as a way of guaranteeing the quality of the code. We relate this practice to how gifts, in the form of new scientific knowledge, are given to the research community, and how this is done through peer review processes.     

Comparison of dextranomer paste and saline dressings for management of decubital ulcers

In this open-label, parallel-group study, 23 male spinal cord injury patients aged 23 to 73 years (median 54 years) with a total of 30 exudative decubital ulcers were randomly allocated to receive treatment with dextranomer paste (15 ulcers) or conventional saline dressings (15 ulcers). Treatment was applied at least once every 12 hours and continued for a maximum of 15 days, until the ulcer was clean and covered with new granulation tissue and was suitable for skin grafting. The same physician assessed ulcer status (extent of drainage, granulation, erythema, and edema and the presence or absence of necrosis and epithelialization) each time the study nurse changed the dressings. Treatment with dextranomer paste resulted in significantly greater improvement in ulcer drainage compared with saline; 73% versus 13% of the ulcers, respectively, showed > or =25% improvement in drainage from baseline to the end of the study. Both treatments were well tolerated, with no evidence of any local irritation. Dextranomer paste was more effective than saline dressings in the management of decubital ulcers in spinal cord injury patients.     

Serum interleukin-6 in relation to acute-phase reactants and survival in patients with renal cell carcinoma

Patients with malignancies often present with signs of inflammatory reactions such as elevated erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). Since interleukin-6 (IL-6) is a possible regulator of these reactions and has been proposed as a predictor of prognosis, the aim of the study was to analyse its clinical significance in patients with renal cell carcinoma. Serum samples were collected from 196 patients before any treatment. IL-6 was analysed by an enzyme-linked immunoassay and compared with tumour grade, stage, acute-phase reactants and survival. Patients with renal cell carcinoma had significantly higher IL-6 levels (mean 28.1 +/- 63.4 ng/l; median 8.3 ng/l) compared with controls (mean 1.7 +/- 2.6 ng/l; median 0.5 ng/l; P < 0.001). Serum IL-6 levels in patients with distant metastases were significantly higher than for patients with tumours confined to the kidney (P = 0.02). This difference was more pronounced when serum IL-6 levels in patients with poorly differentiated tumours were compared with well-differentiated tumours (P < 0.001). A significant correlation between the acute-phase reactants CRP, ESR and IL-6 levels was found. Survival time was significantly shorter (P = 0.001) for patients with IL-6 levels above the median serum level compared with patients with lower levels. Similar significant prognostic results were obtained in the group of patients with metastatic disease, but not in group of patients with stage I-III. Serum levels of IL-6 correlated to tumour stage, grade and acute-phase reactants. Increased levels were related to the presence of metastases and adverse survival. Serum IL-6 proved univariate prognostic information but this prognostic significance was lost using a multivariate analysis.     

Signal profile measurements for evaluation of the volume-selection performance of ISIS

High-resolution signal profiles obtained with a test phantom were used in this study to evaluate the volume-selection performance of an implementation of ISIS (Image Selected In vivo Spectroscopy). The phantom simulated the brain with regard to volume and loading of coil. A remotely controlled, movable signal source inside the phantom was filled with orthophosphoric acid. Signal profiles of the volume of interest (VOI) were measured in three perpendicular directions. Special interest was focused on the transition zones, the position of the profiles, and the effects of off-resonance and T1 smearing. The transition zones were on average 5.6 mm wide and the full width at half maximum (FWHM) was 35 mm for a VOI of 40 x 40 x 40 mm3. The positions of the centre of the signal profiles were x = 3.2, y = -0.7 and z = 3.3 mm off-centre. The deviation of the volume position could be explained by off-resonance effects during imaging and spectroscopy. These data illustrate the importance of detailed knowledge of the volume-selection performance when attempting precision measurements using image-guided in vivo MRS.