| 1. |
- Thunberg, Per, 1968-, et al.
(författare)
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Noise distribution in SENSE- and GRAPPA-reconstructed images : a computer simulation study
- 2007
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Ingår i: Magnetic Resonance Imaging. - New York, USA : Elsevier. - 0730-725X .- 1873-5894. ; 25:7, s. 1089-1094
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Tidskriftsartikel (refereegranskat)abstract
- This work presents a descriptive study of noise distributions in images reconstructed according to the parallel imaging methods SENSE and GRAPPA. In the computer simulations, two different settings were used for describing an object. The first setting included a synthetic object and eight complex-valued coil sensitivities. In the second setting, a complex-valued in vitro object, composed of four individual coil images, was used. After adding noise and subsampling k-space for each coil image, reconstruction was performed according to SENSE, with and without regularization, and GRAPPA for different reduction factors. A set of images was created for three different reduction factors. Noise distributions were determined for each data set and compared with each other. The results of this study show that the noise distributions in SENSE- and GRAPPA-reconstructed images differ. The noise in images reconstructed according to GRAPPA has a more uniform spatial distribution compared with SENSE-reconstructed images, in which the noise varies regionally according to the geometry factor. The noise distribution in SENSE-reconstructed images using regularization showed a similar but lowered pattern of noise compared with images reconstructed according to SENSE without regularization.
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| 2. |
- Garcia-Garcia, Laura, et al.
(författare)
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Measurements of MIMO indoor channels at 1800 MHz with multiple indoor and outdoor base stations
- 2007
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Ingår i: EURASIP Journal on Wireless Communications and Networking. - : Springer Science and Business Media LLC. - 1687-1472 .- 1687-1499.
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Tidskriftsartikel (refereegranskat)abstract
- This paper proposes several configurations for multiple base stations in indoor MIMO systems and compares their performance. The results are based on channel measurements realized with a MIMO testbed. The receiver was moved along several routes and floors on an office building. Both outdoor and indoor locations are considered for the transmitters or base stations, which allow the analysis of not only indoor but also outdoor-to-indoor environment. The use of 2 base stations with different system level combinations of the two is analyzed. We show that the 2 x 4 configuration with base station selection provides almost as good performance as a 4 x 4 full water-filling scheme when the 2 base stations are placed at different locations. Also the spatial correlation properties for the different configurations are analyzed and the importance of considering path loss when evaluating capacity is highlighted.
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| 3. |
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| 4. |
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| 5. |
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| 6. |
- Johansson, Per, et al.
(författare)
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Cerebrospinal Fluid Biomarkers for Alzheimer's Disease: Diagnostic Performance in a Homogeneous Mono-Center Population
- 2011
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Ingår i: Journal of Alzheimer's Disease. - 1387-2877 .- 1875-8908. ; 24:3, s. 537-546
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Tidskriftsartikel (refereegranskat)abstract
- The cerebrospinal fluid (CSF) biomarkers amyloid-beta (A beta)(1-42), T-tau, and P-tau have good diagnostic accuracy for clinically diagnosed Alzheimer's disease (AD). However, in multi-center studies, the predictive values of the CSF biomarkers have been lower, possibly due to differences in procedures for lumbar puncture and CSF handling and storage, and to differences in patient populations, clinical evaluations, and diagnostic procedures. Here we investigate the diagnostic accuracy of CSF biomarkers in a well defined homogeneous mono-center population. We also evaluate an extended panel of amyloid related biomarkers. Sixty consecutive patients admitted for cognitive impairment to a memory clinic were recruited. The participants included patients with AD or mild cognitive impairment (MCI) diagnosed with AD upon follow-up (n = 32), patients with stable MCI (n = 13), patients with other dementias diagnosed at primary evaluation or upon follow-up (n = 15), and healthy controls (n = 20). CSF was analyzed for A beta(1-42), T-tau, P-tau, A beta(X-38), A beta(X-40), A beta(X-42), sA beta PP alpha, and sA beta PP beta. In multivariate analysis, the core biomarkers A beta(1-42), T-tau, and P-tau demonstrated a high ability to diagnose AD versus the combined groups of controls and stable MCI, with an area under the receiver operating characteristic curve (AUROC) of 0.97 (95% CI 0.93-1.00, p < 0.0001). The additional biomarkers only marginally increased AUROC to 0.98 (95% CI 0.95-1.00, p < 0.0001), this increase mainly mediated by A beta(X-42). In conclusion, CSF biomarkers A beta(1-42), T-tau, and P-tau have very high diagnostic accuracy in a well defined cohort of untreated patients, demonstrating the excellent potency of CSF biomarkers to identify pathological processes in AD when a stringent analytical protocol is used.
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| 7. |
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| 8. |
- Johansson, Per, 1966, et al.
(författare)
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Cerebrospinal fluid substance P concentrations are elevated in patients with Alzheimer's disease.
- 2015
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Ingår i: Neuroscience letters. - : Elsevier BV. - 1872-7972 .- 0304-3940. ; 609, s. 58-62
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Tidskriftsartikel (refereegranskat)abstract
- The neuropeptides substance P, orexin A (hypocretin-1) and neurotensin are signaling molecules that influence brain activity. We examined their cerebrospinal fluid (CSF) levels in a study population consisting of Alzheimer's disease (AD) dementia or mild cognitive impairment (MCI) diagnosed with AD dementia upon follow-up (n=32), stable MCI (SMCI, n=13), other dementias (n=15), and healthy controls (n=20). CSF substance P level was increased in AD patients compared to patients with other dementias and healthy controls (P<0.05 and P<0.01, respectively). Patients with other dementia or SMCI had lower CSF orexin A level than AD patients (both P<0.05) and marginally lower level than healthy controls (both P=0.05). CSF neurotensin level was similar in all groups. In the total study population (n=80), CSF substance P level correlated positively with CSF levels of T-tau and P-tau, and in AD patients (n=32), CSF substance P level correlated positively with CSF Aβ1-42 level. In conclusion, CSF substance P level was elevated in AD patients and correlated with CSF Aβ1-42 level, a well established marker of senile plaque pathology. The role of low CSF orexin A level in other dementias or SMCI needs to be explored in further studies.
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| 9. |
- Johansson, Per, 1966, et al.
(författare)
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Reduced Cerebrospinal Fluid Concentration of Apolipoprotein A-I in Patients with Alzheimer's Disease.
- 2017
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Ingår i: Journal of Alzheimer's disease : JAD. - 1875-8908 .- 1387-2877. ; 59:3, s. 1017-1026
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Tidskriftsartikel (refereegranskat)abstract
- Apolipoprotein E (ApoE) has been extensively studied in Alzheimer's disease (AD), but little is known of apolipoprotein A-I (ApoA-I) in cerebrospinal fluid (CSF).Plasma lipids as well as ApoA-I and ApoE in plasma and CSF were determined and related to Mini-Mental State Examination (MMSE) score, APOE genotype, and CSF AD biomarkers.Consecutive patients with AD (n=29), stable mild cognitive impairment (n=13), other dementias (n=14), and healthy controls (n=18) were included at a single center.AD patients had higher plasma triglycerides and lower CSF ApoA-I concentration than controls (both p<0.05). CSF ApoE concentration was reduced in other dementias (p<0.01). In AD as well as other dementias, the ratios between CSF and plasma concentrations of both ApoA-I and ApoE were lower than those in the controls. ApoA-I and ApoE in plasma and CSF were not influenced by APOEɛ4 allele distribution. In the total study population (n=74), CSF ApoA-I correlated positively with MMSE score (r=0.26, p<0.05) and negatively with CSF P-tau (r=-0.25, p<0.05). CSF ApoE correlated positively with CSF concentrations of T-tau and P-tau in the total study population and in AD patients.CSF ApoA-I was reduced in AD patients and associated with measures of cognitive function and AD disease status. The mechanisms underlying the decreased CSF:plasma ratios of ApoA-I and ApoE in AD and other dementias need to be explored in further studies.
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| 10. |
- Johansson, Per, 1966, et al.
(författare)
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Reduced cerebrospinal fluid concentration of interleukin-12/23 subunit p40 in patients with cognitive impairment.
- 2017
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Ingår i: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 12:5
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Tidskriftsartikel (refereegranskat)abstract
- The role of inflammation in Alzheimer's disease (AD) and other cognitive disorders is unclear. In a well-defined mono-center population, we measured cytokines and chemokines in paired serum and cerebrospinal fluid (CSF) samples.Consecutive patients with AD (n = 30), stable mild cognitive impairment (SMCI, n = 11), other dementias (n = 11), and healthy controls (n = 18) were included. None of the subjects was treated with glucocorticoids, cholinesterase inhibitors, or non-steroidal anti-inflammatory drugs. Serum and CSF concentrations of interleukin-6 (IL-6), IL-8, IL-12/23 p40, IL-15, IL-16, vascular endothelial growth factor-A (VEGF-A), and three chemokines were measured using a multiplex panel.After correction for multiple comparisons, only CSF IL-12/23 p40 concentration differed significantly between the total patient group (n = 52) and controls (n = 18; p = 0.002). Further analyses showed that CSF IL-12/23 p40 concentration was decreased in all patient subgroups (AD, other dementias, and SMCI) compared to healthy controls (p < 0.01, p < 0.05, and p < 0.05, respectively). In the total study population (n = 70), CSF IL-12/23 p40 concentrations correlated positively with CSF concentrations of β-amyloid1-42 (Aβ1-42) and phosphorylated tau protein (P-tau) whereas in AD patients (n = 30), CSF IL-12/23 p40 only correlated positively with CSF P-Tau (r = 0.46, p = 0.01).Most cytokines and chemokines were similar in patients and controls, but CSF IL-12/23 subunit p40 concentration was decreased in patients with cognitive impairment, and correlated with markers of AD disease status. Further studies are needed to evaluate the role of CSF IL-12/23 p40 in other dementias and SMCI.
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| 11. |
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| 12. |
- Lundin, Henrik, et al.
(författare)
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ADC imperfections in multiple antenna wireless systems - An experimental study
- 2004
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Ingår i: 9th IMEKO Workshop on ADC Modeling and Testing, IWADC 2004, Held Together with the 13th IMEKO TC4 Symposium on Measurements for Research and Industrial Applications. - : IMEKO-International Measurement Federation Secretariat. - 9781634391856 ; , s. 84-89
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Konferensbidrag (refereegranskat)abstract
- This paper investigates some of the effects that ADC imperfections may have on wireless communication systems. First, an experimental communication system for wireless multiple-input multiple-output (MIMO) is described. In this test bed, an ADC behavioural model has been implemented. The resulting performance of the communication system, in terms of bit error rate, is assessed when the parameters of the ADC model are altered. The results show that, for this system, the ADC resolution is the key parameter while the non-linearity errors are of minor importance.
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| 13. |
- Mattsson, Niklas, 1979, et al.
(författare)
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Cerebrospinal Fluid Microglial Markers in Alzheimer's Disease: Elevated Chitotriosidase Activity but Lack of Diagnostic Utility
- 2011
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Ingår i: NeuroMolecular Medicine. - : Springer Science and Business Media LLC. - 1535-1084 .- 1559-1174. ; 13:2, s. 151-159
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Tidskriftsartikel (refereegranskat)abstract
- Activated microglial cells, which are the resident macrophages of the central nervous system, surround amyloid beta-plaques in Alzheimer's disease (AD) brains. Inflammation including microglial activation may contribute in AD pathogenesis, and biomarkers for this process may thus be of value to study AD pathogenesis and might facilitate development of therapies targeting these cells. We therefore examined cerebrospinal fluid (CSF) biomarkers in patients with AD, other dementias, mild cognitive impairment and in healthy controls. Samples were analyzed for markers with known association to macrophage activity, including chitotriosidase, YKL-40 (CHI3L1, HC gp-39) and chemokine CC motif ligand 2 (CCL2, MCP1). Patients with AD had higher chitotriosidase activity than controls and patients with stable mild cognitive impairment, consistent with the presence of activated microglial cells in AD brains, but with large overlaps between groups. CCL2 and YKL-40 concentrations did not differ among groups. Microglial markers are unlikely to be useful for AD diagnosis, but might be useful for identification of distinct subgroups of patients, and for the development and implementation of drugs targeting microglial pathology.
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| 14. |
- Mattsson, Niklas, 1979, et al.
(författare)
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Converging Pathways of Chromogranin and Amyloid Metabolism in the Brain
- 2010
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Ingår i: Journal of Alzheimer's Disease. - 1387-2877 .- 1875-8908. ; 20:4, s. 1039-1048
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Tidskriftsartikel (refereegranskat)abstract
- Much is unknown regarding the regulation of Alzheimer-related amyloid-beta protein precursor (A beta PP)-processing in the human central nervous system. It has been hypothesized that amyloidogenic A beta PP-processing preferentially occurs in the regulated secretory pathway of neurons. To test this hypothesis we looked for correlations of A beta PP-derived molecules in cerebrospinal fluid (CSF) with chromogranin (Cg) derived peptides, representing the regulated secretion. Patients with Alzheimer's disease (AD, N = 32), multiple sclerosis (MS, N = 50), and healthy controls (N = 70) were enrolled. CSF was analyzed for the amyloid peptides A beta(1-42), A beta(x-42), A beta(x-40), A beta(x-38), alpha-cleaved soluble A beta PP (sA beta PP alpha), beta-cleaved soluble A beta PP (sA beta PP beta), and peptides derived from CgB and SgII (Secretogranin-II, CgC). We investigated CSF levels of the protease BACE1, which processes A beta PP into A beta, in relation to Cg-levels. Finally, we measured Cg levels in cell media from untreated and BACE1-inhibited SH-SY5Y human neuroblastoma cells. CSF Cg levels correlated to sA beta PP and A beta peptides in AD, MS, and controls, and to CSF BACE1. Cell medium from BACE1-inhibited cells had decreased CgB levels. These results suggest that a large part of A beta PP in the human central nervous system is processed in the regulated secretory pathway of neurons.
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| 15. |
- Minta, Karolina, et al.
(författare)
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Brevican and Neurocan Peptides as Potential Cerebrospinal Fluid Biomarkers for Differentiation Between Vascular Dementia and Alzheimer's Disease
- 2021
-
Ingår i: Journal of Alzheimer's disease : JAD. - 1387-2877 .- 1875-8908. ; 79:2, s. 729-741
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Brevican and neurocan are central nervous system-specific extracellular matrix proteoglycans. They are degraded by extracellular enzymes, such as metalloproteinases. However, their degradation profile is largely unexplored in cerebrospinal fluid (CSF).OBJECTIVE: The study aim was to quantify proteolytic peptides derived from brevican and neurocan in human CSF of patients with Alzheimer's disease (AD) and vascular dementia (VaD) compared with controls.METHODS: The first cohort consisted of 75 individuals including 25 patients with AD, 7 with mild cognitive impairment (MCI) diagnosed with AD upon follow-up, 10 patients with VaD or MCI diagnosed with VaD upon follow-up, and 33 healthy controls and cognitively stable MCI patients. In the second cohort, 31 individuals were included (5 AD patients, 14 VaD patients and 12 healthy controls). Twenty proteolytic peptides derived from brevican (n = 9) and neurocan (n = 11) were quantified using high-resolution parallel reaction monitoring mass spectrometry.RESULTS: In the first cohort, the majority of CSF concentrations of brevican and neurocan peptides were significantly decreased inVaDas compared withADpatients (AUC = 0.83.0.93, p≤0.05) and as compared with the control group (AUC = 0.79.0.87, p ≤ 0.05). In the second cohort, CSF concentrations of two brevican peptides (B87, B156) were significantly decreased in VaD compared with AD (AUC = 0.86.0.91, p ≤ 0.05) and to controls (AUC = 0.80.0.82, p ≤ 0.05), while other brevican and neurocan peptides showed a clear trend to be decreased in VaD compared with AD (AUC = 0.64.80, p > 0.05). No peptides differed between AD and controls.CONCLUSION: Brevican and neurocan peptides are potential diagnostic biomarkers for VaD, with ability to separate VaD from AD.
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| 16. |
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| 17. |
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| 18. |
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| 19. |
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| 20. |
- Paterson, R W, et al.
(författare)
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A targeted proteomic multiplex CSF assay identifies increased malate dehydrogenase and other neurodegenerative biomarkers in individuals with Alzheimer's disease pathology.
- 2016
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Ingår i: Translational psychiatry. - : Springer Science and Business Media LLC. - 2158-3188. ; 6:11
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Tidskriftsartikel (refereegranskat)abstract
- Alzheimer's disease (AD) is the most common cause of dementia. Biomarkers are required to identify individuals in the preclinical phase, explain phenotypic diversity, measure progression and estimate prognosis. The development of assays to validate candidate biomarkers is costly and time-consuming. Targeted proteomics is an attractive means of quantifying novel proteins in cerebrospinal and other fluids, and has potential to help overcome this bottleneck in biomarker development. We used a previously validated multiplexed 10-min, targeted proteomic assay to assess 54 candidate cerebrospinal fluid (CSF) biomarkers in two independent cohorts comprising individuals with neurodegenerative dementias and healthy controls. Individuals were classified as 'AD' or 'non-AD' on the basis of their CSF T-tau and amyloid Aβ1-42 profile measured using enzyme-linked immunosorbent assay; biomarkers of interest were compared using univariate and multivariate analyses. In all, 35/31 individuals in Cohort 1 and 46/36 in Cohort 2 fulfilled criteria for AD/non-AD profile CSF, respectively. After adjustment for multiple comparisons, five proteins were elevated significantly in AD CSF compared with non-AD CSF in both cohorts: malate dehydrogenase; total APOE; chitinase-3-like protein 1 (YKL-40); osteopontin and cystatin C. In an independent multivariate orthogonal projection to latent structures discriminant analysis (OPLS-DA), these proteins were also identified as major contributors to the separation between AD and non-AD in both cohorts. Independent of CSF Aβ1-42 and tau, a combination of these biomarkers differentiated AD and non-AD with an area under curve (AUC)=0.88. This targeted proteomic multiple reaction monitoring (MRM)-based assay can simultaneously and rapidly measure multiple candidate CSF biomarkers. Applying this technique to AD we demonstrate differences in proteins involved in glucose metabolism and neuroinflammation that collectively have potential clinical diagnostic utility.
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| 21. |
- Rosén, Christoffer, 1986, et al.
(författare)
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Discriminatory analysis of biochip-derived protein patterns in CSF and plasma in neurodegenerative diseases
- 2011
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Ingår i: Frontiers in Aging Neuroscience. - : Frontiers Media SA. - 1663-4365. ; 3
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Tidskriftsartikel (refereegranskat)abstract
- The role of biomarkers in neurodegenerative diseases has been emphasized by recent research. Future clinical demands for identifying diseases at an early stage may render them essential. The aim of this pilot study was to test the analytical performance of two multiplex assays of cerebral markers on a well-defined clinical material consisting of patients with various neurodegenerative diseases. We measured 10 analytes in plasma and cerebrospinal fluid (CSF) from 60 patients suffering from Alzheimer's disease (AD), vascular dementia, frontotemporal dementia, dementia with Lewy bodies, or mild cognitive impairment, as well as 20 cognitively healthy controls. We used the Randox biochip-based Evidence Investigator™ system to measure the analytes. We found it possible to measure most analytes in both plasma and CSF, and there were some interesting differences between the diagnostic groups, although with large overlaps. CSF heart-type fatty acid-binding protein was increased in AD. Glial fibrillary acidic protein and neutrophil gelatinase-associated lipocalin in CSF and D-dimer in plasma were elevated in patients with cerebrovascular disease. A multivariate statistical analysis revealed that the pattern of analytes could help to differentiate the conditions, although more studies are required to verify this.
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| 22. |
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| 23. |
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| 24. |
- Zetterberg, Per, 1968-, et al.
(författare)
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Experiments Using an Antenna Array in a Mobile Communications Environment
- 1994
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Ingår i: IEEE Seventh SP Workshop on Statistical Signal and Array Processing. ; , s. 137-140
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Konferensbidrag (refereegranskat)abstract
- The goal of this paper is to obtain knowledge about spatial characteristics of the mobile channel seen through an antenna array. Particular interest is paid to the effect of local scattering. i.e large number of rays in the vicinity of the mobile.
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| 25. |
- Zetterberg, Per, 1968-, et al.
(författare)
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Implementation and Testing of Co-Operative Schemes on a Real-Time DSP-Based Testbed
- 2009
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Ingår i: ICT-MobileSummit 2009 Conference Proceedings.
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Konferensbidrag (refereegranskat)abstract
- Experimental and simulation results on well-known co-operating relayingschemes such as: amplify-and-forward (AF), detect-and-forward (DF), co-operativemaximum-ratio combining (CMRC), and distributed space-time coding (DSTC) arepresented in this paper. A novel relaying scheme named “selection relaying” (SR), inwhich one of two relays are selected base on path-loss, is also tested.We also implement the modes “Selective” and “Antenna Diversity”. The “Selective”option is designed to avoid forwarding of erroneous frames.In our measurements, all co-operative relaying schemes above increase the coveragearea as compared with direct transmission. The features “Antenna diversity” and “Selective”improve the performance. Good performance is obtained with CMRC, DSTCand SR.
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| 26. |
- Zetterberg, Per, 1968-, et al.
(författare)
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Implementation of SM and RxTxIR on a DSP-Based Wireless MIMO Test-Bed
- 2004
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Ingår i: Proceedings of the European DSP Education and Research Symposium EDERS.
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Konferensbidrag (refereegranskat)abstract
- In this paper we describe the implementation of two smart-antenna strategies and associated signal processing algorithms on a common DSP-based wireless MIMO test-bed. The test-bed supports single cell and two-cell configurations. All nodes (MS andBS) have two antennas (either two transmit or tworeceive) and there are feedback links (via cable) from the receivers to all transmitters.These possibilities has been utilized differently in the two techniques: spatial multiplexing (SM) and joint receiver transmitter and interference rejection (RxTxIR).The SM technique targets a single-link low-mobility scenario and boosts throughput using two parallel spatially multiplexed modulation streams. The RxTxIR scheme utilizes the two-cell configuration of the testbed to demonstrate the possibility of suppressing intercell interference in transmitter as well as the receiver beamforming.
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| 27. |
- Zetterberg, Per, 1968-, et al.
(författare)
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Investigation of Simple Algorithms for Estimation of Delay-Spread and Angle-Spread
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In this paper we describe two simple methods for estimation of delay-spread and angle-spread, re-spectively. The algorithms are simple in the sense that the transmitted signal may consist of only threesuperimposed CW tones -and the receiver need only two antennas. The algorithms are also simple in thesense that the computational cost is very low. We verify the algorithms by applying them to wideband andmulti-antenna measurement data, respectively.
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| 28. |
- Zetterberg, Per, 1968-
(författare)
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Method for Decreasing Fading in a Telecommunication System
- 1998
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Patent (populärvet., debatt m.m.)abstract
- The present invention provides a method for decreasing fading and more particularly the down-link fading in a mobile telecommunication system having transmit lobe diversity. The telecommunication system comprises at least one base station having an antenna array providing lobe diversity, and communicating with mobile terminal units. According to the invention, the average path-loss between the base station and a mobile terminal unit is measured by the base station in order to select a set of alternative lobes. The instantaneous down-link path-loss of the alternative lobes between the base station and the mobile terminal unit is also measured by the mobile in order to select a communication lobe from said set of alternative lobes, such that the communication is effected in the communication lobe.
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| 29. |
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| 30. |
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| 31. |
- Zetterberg, Per, 1968-, et al.
(författare)
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The Spectrum Efficiency of a Base-Station Antenna Array System for Spatially Selective Transmission
- 1994
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Ingår i: IEEE 44th Vehicular Technology Conference. - : IEEE. ; , s. 1517-1521
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Konferensbidrag (refereegranskat)abstract
- The goal of this paper is to estimate the gain, in terms of system capacity at a given outage probability, which can be obtained by applying antenna arrays in the base stations of a mobile cellular network. For this purpose apropagation model which incorporates the angular distribution of the rays in the vicinity of the mobile is postulated. Also included in the model is the interference from co-channel cells. With the aid of the model, aweight selection algorithm is derived. The proposed system is simulated with different numbers of mobiles per channel in each cell and different numbers of antenna elements in the arrays. Also varied is the cluster size. This is done to determine the optimal trade-off between reduced cluster size and multiple mobiles per channel in each cell. The results show that it is possible to increase capacity between two and twelve times depending on thenumber of antennas in the arrays and the spread of the local scattering.
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| 32. |
- Zetterberg, Per, 1968-
(författare)
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WIreless DEvelopment LABoratory(WIDELAB) Equipment Base
- 2013
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This paper documents some of the hard- and soft-ware used by the signal- processing group at KTH, in it’s experimental work on wireless systems. We call these items collectively WIreless DEvelopment LABoratory (WIDELAB), and this paper aims to document the most important pieces and some of the knowledge needed to understand, operate and develop them further. To access the hard and software described contact perz@s3.kth.se
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| 33. |
- Zhang, Shuai, et al.
(författare)
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Printed MIMO antenna system of four closely-spaced elements with large bandwidth and high isolation
- 2010
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Ingår i: Electronics Letters. - : Institution of Engineering and Technology (IET). - 0013-5194 .- 1350-911X. ; 46:15, s. 1052-1053
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Tidskriftsartikel (refereegranskat)abstract
- A compact wideband printed MIMO antenna system (of four elements) with high isolation is presented. The proposed MIMO antenna system with an overall lateral size of only 0.43 lambda x 0.43 lambda can offer 22.8% bandwidth (1.63-2.05 GHz) and isolation of better than 24 dB. The measured gain is larger than 2.72 dBi over the whole band, and the calculated envelope correlation coefficient is better than 0.01. The radiation patterns and MIMO channel capacity are also measured.
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| 34. |
- Zhang, Xi, et al.
(författare)
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Implementation of a smart antenna multiuser algorithm on a DSP-based wireless MIMO test-bed
- 2005
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Ingår i: IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC. ; , s. 126-130
-
Konferensbidrag (refereegranskat)abstract
- This paper describes the implementation and performance of three communication schemes on a DSP-based MIMO test-bed. A multicell scenario with two basestations and two users in the same room is evaluated. Eigenbeamforming with and without interference pre-whitening at both transmitter and receiver is compared with SISO multicell communication. Experimental results show that the gain from using interference pre-whitening is significant. The BER performance of beamforming without intercell interference suppression is only marginally better than single antenna communication. The paper also presents the implementation of synchronization, equalization, frequency offset estimation and decision directed beamforming mismatch compensation.
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| 35. |
- Åberg, Daniel, 1973, et al.
(författare)
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Increased Cerebrospinal Fluid Level of Insulin-like Growth Factor-II in Male Patients with Alzheimer's Disease
- 2015
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Ingår i: Journal of Alzheimers Disease. - : IOS Press. - 1387-2877 .- 1875-8908. ; 48:3, s. 637-646
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Insulin-like growth factor-II (IGF-II) is important for brain development. Although IGF-II is abundant also in adult life, little is known of the role of IGF-II in Alzheimer's disease (AD). Objective and methods: This was a cross-sectional study of 60 consecutive patients under primary evaluation of cognitive impairment and 20 healthy controls. The patients had AD dementia or mild cognitive impairment (MCI) diagnosed with AD dementia upon follow-up (n = 32), stable MCI (SMCI, n = 13), or other dementias (n = 15). IGF-II, IGF-binding protein-1 (IGFBP-1), and IGFBP-2 were analyzed in serum and cerebrospinal fluid (CSF). Results: Levels of IGF-II, IGFBP-1, and IGFBP-2 were similar in all groups in the total study population. Gender-specific analyses showed that in men (n = 40), CSF IGF-II level was higher in AD compared to SMCI and controls (p < 0.01 and p < 0.05, respectively). Furthermore, CSF IGFBP-2 levelwas increased inADmen versus SMCI men (p < 0.01) and tended to be increased versus control men (p = 0.09). There were no between-group differences in women (n = 40). In the total study population (n = 80) as well as in men (n = 40), CSF levels of IGF-II and IGFBP-2 correlated positively with CSF levels of the AD biomarkers total-tau and phosphorylated tau protein. Conclusion: In men, but not women, in the early stages of AD, CSF IGF-II level was elevated, and CSF IGFBP-2 level tended to be increased, compared to healthy controls.
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| 36. |
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