855 research outputs found
When Are Errors-in-Variables Aspects Important to Consider in System Identification?
No full textWhen recorded signals are corrupted by noise on both input and output sides, standard identification methods give biased parameter estimates, due to the presence of input noise. This paper discusses in what situations such a bias is large and, consequently, when errors-in-variables identification methods should preferably be used
IgG subclass deficiency in patients with Down's syndrome and aberrant hepatitis B vaccine response.
No full textSeventeen adult patients with Down's syndrome (DS) and 19 adult healthy references were vaccinated with a hepatitis B vaccine in order to study the IgG subclass response. An enzyme-linked immunosorbent assay (ELISA) using monoclonal antibodies specific for IgG subclasses was employed. In spite of normal levels of total IgG1 and normal or even high levels of IgG3 in the DS patients, a significantly lower IgG1 response to the vaccine was observed in trisomic patients than in the references
Monetary Policy, Doubts and Asset Prices
No full textAsset prices and the equity premium might reflect doubts and pessimism. Introducing these features in an otherwise standard New-Keynesian model changes in a quite substantial way the nature of the policy that maximizes the welfare of the consumers in the model. First, following productivity shocks, optimal policy in this model is more accommodating than in a standard New-Keynesian model, and may even inflate the equity premium. Second, asset-price movements improve the inflation-output trade-off so that average output can rise without increasing much average inflation. Finally, a strict inflation-targeting policy may result in lower average welfare than a more flexible inflation-targeting policy, which instead increases the comovements between inflation, asset prices and output growth.
Comparison of three Frisch methods for errors-in-variables identification
No full textThe errors–in–variables framework concerns static or dynamic systems whose input and output variables are affected by additive noise. Several estimation methods have been proposed for identifying dynamic errors–in–variables models. One of the more promising approaches is the so–called Frisch scheme. This paper decribes three different estimation criteria within the Frisch context and compares their estimation accuracy on the basis of the asymptotic covariance matrices of the estimates. Some numerical examples support well the theoretical results
CD4+CD25+ T regulatory cells in multiple sclerosis
No full textMultiple sclerosis (MS) is a chronic, inflammatory, and demyelinating disease of the central nervous system (CNS), which is likely to be mediated by autoaggressive immunity. Treatments of MS that may beneficially influence the disease course consist of Avonex (interferon-beta; IFN-beta), and Copaxone (glatiramer acetate; GA). Studies in experimental autoimmune encephalomyelitis (EAE), a commonly used experimental model of human MS, have demonstrated a crucial role of CD4+CD25+ T regulatory (Tr) cells in suppressing autoreactive T cells and promoting peripheral tolerance. Recent studies have shown that Tr cells inhibiting the proliferation and cytokine secretion by CD4+ T cells, are enriched in the CD25high cells among CD4+ T cells. It is not yet known if circulating CD4+CD25 high Tr cells are involved in MS.The aims of this study were to:1. identify and quantify CD4+CD25+ and CD4+CD25high Tr cells among blood CD4+ T cells, and proportions of CD4+CD25high Tr cells expressing cell surface and intracellular molecules in patients with untreated MS vs MS treated with either IFN-beta-1a or GA or the combination of IFN-beta-1a+GA vs healthy controls (HC);2. to correlate the properties of circulating CD4+CD25+ Tr cells with lesion load (LL) and gadolinium (Gd) enhancement detected by magnetic resonance imaging (MRI) of the brain in untreated MS patients.3. analyse the in-vitro influence of GA upon CD4+CD25 high Tr cells from MS patients vs from HC.4. examine whether a functional deficit inherent to CD4+CD25+ Tr cells occurred in untreated MS patients vs HQ in terms of the ability of Tr cells to suppress the production of pro-inflammatory cytokines by blood mononuclear cells (MNC) upon auto- or foreign-antigenic stimulation.These studies demonstrated that i) there are no alterations of frequency of circulating CD4+CD25+ and CD4+CD25high Tr cells nor of the proportions of CD4+CD25 high Tr cells expressing CD45RO, HLADR, CD95, CTLA-4 or IL-10 in MS patients compared to HQ ii) the frequency of CD4+CD25+ Tr cells, and the proportions of IL-10 expressing CD4+CD25+ Tr cells are elevated in MS patients with Gdenhancing lesions; iii) the proportion of CXCR3+ CD4+ T cells is lower in the group of patients with Gdenhancing lesions on T1weighted images, as compared to the group with no Gd-enhancing lesions; iv) GA, in vitro elevates the levels of IL-10 producing blood CD4+CD25 high Tr cells in both MS patients and HC, and; v) CD4+CD25+ Tr cells augments the secretion of Th1 cytokines IFN-gamma and IL-2, but not of Th.2 cytokine IL-13 in response to MBP, equally in MS patients and HC, suggesting that the functional activity of CD4+CD25+ Tr cells in terms of controlling Th1 and Th2 cytokine secretions in response to MBP, is not significantly altered in MS.List of scientific papersI. Putheti P, Pettersson A, Soderstrom M, Link H, Huang YM (2004). Circulating CD4(+)CD25(+) T Regulatory Cells Are Not Altered in Multiple Sclerosis and Unaffected by Disease-Modulating Drugs. J Clin Immunol. 24(2): 155-61. https://pubmed.ncbi.nlm.nih.gov/15024182II. Putheti P, Morris M, Stawiarz L, Teleshova N, Kivisakk P, Pashenkov M, Kouwenhoven M, Wiberg MK, Bronge L, Huang YM, Soderstrom M, Hillert J, Link H (2003). Multiple sclerosis: a study of chemokine receptors and regulatory T cells in relation to MRI variables. Eur J Neurol. 10(5): 529-35. https://pubmed.ncbi.nlm.nih.gov/12940835III. Putheti P, Soderstrom M, Link H, Huang YM (2003). Effect of glatiramer acetate (Copaxone) on CD4+CD25high T regulatory cells and their IL-10 production in multiple sclerosis. J Neuroimmunol. 144(1-2): 125-31. https://pubmed.ncbi.nlm.nih.gov/14597106IV. Ptheti P, Pashenkov M, Huang YM, Soderstrom M, Link H (2004). Multiple sclerosis: No evidence of functional deficit of CD4+CD25+T regulatory cells. [Manuscript]</p
Analysis of gamma-delta V region usage in normal and diseased human intestinal biopsies and peripheral blood by polymerase chain reaction (PCR) and flow cytometry
No full textThe intestinal population of gamma delta T cell receptor (TCR)-bearing cells was characterized with regard to V delta and V gamma subtype expression. For this purpose, we utilized V gene-specific PCR of mRNA prepared from intestinal biopsies. Predominant expression of the V delta 1 subtype was demonstrated in the small intestine of patients with coeliac disease and in the inflamed colon of patients with inflammatory bowel diseases (IBD: ulcerative colitis and Crohn's disease) as well as in colon biopsies taken from macroscopically normal areas of colon. Although intestinal gamma delta T cells preferentially expressed V delta 1, other V delta transcripts could be detected, of which V delta 2 and V delta 5 were commonly expressed. Analysis of biopsies from mesenteric lymph nodes demonstrated a V delta repertoire similar to the mucosa. In peripheral blood on the other hand, high expression of both V delta 2 and V delta 1 was found. The predominant expression of V delta 1 transcripts in the intestinal mucosa of IBD patients correlated well with protein cell surface expression as analysed by flow cytometry using V delta 1- and V delta 2-specific antibodies. Selective expansion of gamma delta T cells could not be demonstrated within the inflamed mucosa as shown by mRNA analysis and flow cytometry. Instead, IBD patients demonstrated a decreased proportion of TCR gamma delta-carrying T cells in the inflamed mucosa compared with macroscopically normal area of colon. On the other hand, a significantly increased percentage of T cells bearing the gamma delta TCR was found in peripheral blood of patients with Crohn's disease compared with healthy individuals, indicating that local mucosal inflammation may influence the circulating gamma delta T cell population
Evolution of life history strategies in Lophoziaceae
No full textThis study used data from literature and data from the field to analyse the patterns of variation in life history characters among members of the liverwort family Lophoziaceae. A combination of Principal Component and Cluster analyses was used to analyse data from literature in testing for recurrent suites of life history variation among species of the family. Data from literature were also used to examine the relationship between mode of reproduction and reproductive system (sexuality) and between diaspore (spore or gemma) frequency and sexuality. Data from the field were used to establish diaspore (spore and gemma) sizes and their production per capsule or shoot and to test for relationships between diaspore size and production per shoot/capsule and also between diaspore sizes and proportion of germination. The study showed the existence of recurrent suites of life history variation in the family. The clusters produced were shown to be independent of the species' phylogeny, but were closely related to the habitat parameters such as nature of substrate, duration of habitat availability and moisture condition. The study also shows dominance of dioicous species in the family, with about 90% of the studied species being dioicous. There is a statistically significant relationship between reproductive system and sporophyte frequency; monoicous species produce sporophytes more frequently than dioicous species. A negative relationship was shown to generally exist between spore size and number of spores produced per capsule at both species and population levels. However, no relationship could be established between gemma size and the number of gemmae produced per shoot. For two of the studied species, L. ciliata and L. /ongiflora, there was a general positive relationship between spore size and proportion of germination, with bigger spores having higher germination proportions. L ventricosa showed a negative relationship between spore size and germinability
Evaluating electricity distribution network reconfiguration to minimize power loss on existing networks
No full textThis paper applies the distribution network reconfiguration problem to existing networks. The medium voltage distribution network of the Dutch DSO Alliander is operated using a radial topology. By optimizing this topology it is possible to reduce the energy losses caused by the cable impedances. Various solutions algorithms have been compared for this distribution network reconfiguration problem, while taking into account network capacity and voltage levels. A Genetic algorithm combined with a Greedy demeshing starting condition yields the best results. Applying the algorithm on real life distribution networks shows with 226 buses and 406 buses yield a reduction in power losses of 15% and 27% respectively.Support Delft Center for Systems and Contro
Taxonomic status of the endemic South African bamboo, <i>Thamnocalamus tessellatus</i>
No full textThamnocalamus tessellatus (Nees) Soderstrom & Ellis, [= Arundinaria tessellata (Nees) Munro] is the only endemic South African bamboo and occurs from the eastern districts of the Cape, through Lesotho and Natal, to the eastern Orange Free State at elevations of about 1 500-2 500 m. The Mountain Bamboo, or ‘Bergbamboes’ was first described by Nees in 1841 as a member of the genus Nastus because of the similarity, to him, of the spikelets between it and N. barbonicus, but was later transferred to the all-encompassing genus of the time, Arundinaria, the type species of which is endemic to the southeastern United States of America. Based on our present knowledge of bamboo genera, this South African species may be excluded from Nastus because the inflorescence is not a panicle but bracteate racemiform, the vegetative branches do not arise in a verticillate manner but are a series of subequal branches that are borne in a row above the nodal line and T. tessellatus has an androecium of three stamens and not six as in Nastus. The Bergbamboes, with sympodial rhizomes and branch complement of several subequal branches, can also not be maintained in Arundinaria, for monopodial rhizomes and a single branch at the node are typical of this genus. The simple, ebracteate, and exserted inflorescence of Arundinaria is also quite distinct from that of the Bergbamboes.
In order to place the South African bamboo more precisely we have made comparative studies of its leaf anatomy and epidermis, gross morphology, and analyses of its inflorescence and spikelets. The results of all these studies reveal a striking resemblance to members of the Sino-Himalayan genus, Thamnocalamus, to which we have accordingly transferred the species. The results are presented, together with an interpretation of the phylogenetic position of the Bergbamboes and possible events that led to the disjunction of species in the genus
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