Showing papers by "Linköping University published in 2000"

Microfabricating Conjugated Polymer Actuators

Abstract: Conjugated polymer actuators can be operated in aqueous media, which makes them attractive for laboratories-on-a-chip and applications under physiological conditions. One of the most stable conjugated polymers under these conditions is polypyrrole, which can be patterned by means of standard photolithography. Polypyrrole-gold bilayer actuators that bend out of the plane of the wafer have been microfabricated in our laboratory. These can be used to move and position other microcomponents. Here we review the current status of these microactuators, outlining the methods used to fabricate them. We describe the devices that have been demonstrated as well as some potential future applications.

Impact of CMOS technology scaling on the atmospheric neutron soft error rate

Abstract: We investigated scaling of the atmospheric neutron soft error rate (SER) which affects reliability of CMOS circuits at ground level and airplane flight altitudes. We considered CMOS circuits manufactured in a bulk process with a lightly-doped p-type wafer. One method, based on the empirical model, predicts a linear decrease of SER per bit with decreasing feature size L/sub G/. A different method, based on the MBGR model, predicts even faster decrease of SER per bit than linear. If the increasing number of bits is taken into account, then the SER per chip is not expected to increase faster than linearly with decreasing L/sub G/.

Comparing Academic Entrepreneurship in Europe – The Case of Sweden and Ireland

Abstract: One of the greatest challenges facing European economies is the comparatively limited capacity to convert scientific breakthroughs and technological achievements into industrial and commercial successes. As a result, there is growing awareness of the proactive approach being undertaken by academic institutions, with many adopting a direct entrepreneurial role in collaborating with industry. This paper examines the activities of those academics involved with industry within two small European countries, namely Sweden and Ireland. In particular, it discusses and contrasts the extent to which academic entrepreneurship (i.e. all commercialisation activities outside of the normal university duties of basic research and teaching) has developed. It examines the influence of gender, age, previous entrepreneurial experience, work experience and university environment on the entrepreneurship activities of a sample of academics in both countries. The results demonstrate that there is considerable entrepreneurial experience among academics in both countries, and that this translates into a high degree of involvement in "soft" activities such as consultancy and contract research, but not into organizational creation via technology spin-offs.

Microrobots for micrometer-size objects in aqueous media: potential tools for single-cell manipulation

Abstract: Conducting polymers are excellent materials for actuators that are operated in aqueous media. Microactuators based on polypyrrole-gold bilayers enable large movement of structures attached to these actuators and are of particular interest for the manipulation of biological objects, such as single cells. A fabrication method for creating individually addressable and controllable polypyrrole-gold microactuators was developed. With these individually controlled microactuators, a micrometer-size manipulator, or microrobotic arm, was fabricated. This microrobotic arm can pick up, lift, move, and place micrometer-size objects within an area of about 250 micrometers by 100 micrometers, making the microrobot an excellent tool for single-cell manipulation.

Large-seeded species are less dependent on light for germination than small-seeded ones

Abstract: Germination in light and darkness was compared after cold stratification of seeds of 54 species known or suspected to accumulate persistent seed banks. Germination became less dependent on light with increasing seed mass. This pattern was clear in a direct correlation of individual species data (P <0.0001) as well as when considering phylogenetically independent contrasts (P <0.001). The latter analysis suggests that light response and seed mass coevolved.

Photochemical transformation of dissolved organic matter in lakes

Abstract: In a survey of photochemical transformation of dissolved organic matter (DOM) in lake water, we found photochemical production of dissolved inorganic carbon (DIC) and low molecular weight carboxyli ...

Ketamine reduces muscle pain, temporal summation, and referred pain in fibromyalgia patients

Abstract: Central mechanisms related to referred muscle pain and temporal summation of muscular nociceptive activity are facilitated in fibromyalgia syndrome (FMS) patients. The present study assessed the ef ...

The Thylakoid FtsH Protease Plays a Role in the Light-Induced Turnover of the Photosystem II D1 Protein

Abstract: The photosystem II reaction center D1 protein is known to turn over frequently. This protein is prone to irreversible damage caused by reactive oxygen species that are formed in the light; the damaged, nonfunctional D1 protein is degraded and replaced by a new copy. However, the proteases responsible for D1 protein degradation remain unknown. In this study, we investigate the possible role of the FtsH protease, an ATP-dependent zinc metalloprotease, during this process. The primary light-induced cleavage product of the D1 protein, a 23-kD fragment, was found to be degraded in isolated thylakoids in the dark during a process dependent on ATP hydrolysis and divalent metal ions, suggesting the involvement of FtsH. Purified FtsH degraded the 23-kD D1 fragment present in isolated photosystem II core complexes, as well as that in thylakoid membranes depleted of endogenous FtsH. In this study, we definitively identify the chloroplast protease acting on the D1 protein during its light-induced turnover. Unlike previously identified membrane-bound substrates for FtsH in bacteria and mitochondria, the 23-kD D1 fragment represents a novel class of FtsH substrate— functionally assembled proteins that have undergone irreversible photooxidative damage and cleavage.

Admissible heuristics for optimal planning

Abstract: HSP and HSPr are two recent planners that search the state-space using an heuristic function extracted from Strips encodings. HSP does a forward search from the initial state recomputing the heuristic in every state, while HSPr does a regression search from the goal computing a suitable representation of the heuristic only once. Both planners have shown good performance, often producing solutions that are competitive in time and number of actions with the solutions found by Graphplan and SAT planners. HSP and HSPr. however, are not optimal planners. This is because the heuristic function is not admissible and the search algorithms are not optimal. In this paper we address this problem. We formulate a new admissible heuristic for planning, use it to guide an IDA* search, and empirically evaluate the resulting optimal planner over a number of domains. The main contribution is the idea underlying the heuristic that yields not one but a whole family of polynomial and admissible heuristics that trade accuracy for efficiency. The formulation is general and sheds some light on the heuristics used in HSP and Graphplan, and their relation. It exploits the factored (Strips) representation of planning problems, mapping shortest-path problems in state-space into suitably defined shortest-path problems in atom-space. The formulation applies with little variation to sequential and parallel planning, and problems with different action costs.

Ionized sputter deposition using an extremely high plasma density pulsed magnetron discharge

Abstract: Time resolved plasma probe measurements of a novel high power density pulsed plasma discharge are presented. Extreme peak power densities in the pulse (on the order of several kW cm−2) result in a very dense plasma with substrate ionic flux densities of up to 1 A cm−2 at source-to-substrate distances of several cm and at a pressure of 0.13 Pa (1 mTorr). The pulse duration was ∼100 μs with a pulse repetition frequency of 50 Hz. The plasma consists of metallic and inert gas ions, as determined from time resolved Langmuir probe measurements and in situ optical emission spectroscopy data. It was found that the plasma composition at the beginning of the pulse was dominated by Ar ions. As time elapsed metal ions were detected and finally dominated the ion composition. The effect of the process parameters on the temporal development of the ionic fluxes is discussed. The ionized portion of the sputtered metal flux was found to have an average velocity of 2500 m s−1 at 6 cm distance from the source, which conforms...

Follow-up study of patients randomized in the scandinavian simvastatin survival study (4S) of cholesterol lowering

Abstract: The Scandinavian Simvastatin Survival Study (4S) and other randomized clinical trials have demonstrated that cholesterol-lowering treatment with statins improves prognosis in patients with coronary atherosclerosis compared with placebo The effect of therapy with statins beyond the typical 5 to 6 years' duration of the trials, in particular regarding the risk of cancer, has not been investigated This study examines the long-term effects of simvastatin for up to 8 years on cause-specific mortality in patients with coronary heart disease (CHD) We performed an observational, government registry-based study of mortality in the groups originally randomized to simvastatin or placebo in the 4S over an additional 2-year follow-up period, so that the median total follow-up period was 74 years (range 69 to 83 in surviving patients) Randomization took place at outpatient clinics at 94 clinical centers in Denmark, Finland, Iceland, Norway, and Sweden from 1988 to 1989 Of 4,444 patients with CHD, 2,223 and 2,221 were randomized to treatment with placebo or simvastatin therapy, respectively Patients received treatment with simvastatin, starting at 20 mg/day, with titration to 40 mg/day at 12 or 24 weeks if total cholesterol was >52 mmol/L (200 mg/dl), or placebo After the double-blind period, most patients in both treatment groups received simvastatin as open-label prescription Of the 1,967 patients originally treated with placebo and surviving the double-blind period, 97 (49%) died during the following 2 years In the group randomized to simvastatin the corresponding number was 74 of the 2, 039 survivors (36%) Adding these deaths to those occurring during the original trial, the total was 353 (159%) and 256 (115%) deaths in the groups originally randomized to placebo and simvastatin, respectively The relative risk was 070 (95% confidence interval 0 60 to 082, p = 000002) The total number of cancer deaths was 68 (31%) in the placebo group and 52 (23%) in the simvastatin group (relative risk 073, 95% confidence interval 051 to 005, p = 0 087), and the numbers of noncardiovascular and other deaths were similar in both groups We therefore conclude that treatment with simvastatin for up to 8 years in patients with CHD is safe and yields continued survival benefit

Biodiversity lessens the risk of cascading extinction in model food webs

Abstract: Due to the complex interactions between species in food webs, the extinction of one species could lead to a cascade of further extinctions and hence cause dramatic changes in species composition an ...

Varieties of long-term outcome among patients in psychoanalysis and long-term psychotherapy. A review of findings in the Stockholm Outcome of Psychoanalysis and Psychotherapy Project (STOPP).

Abstract: This paper reports the main findings of a large-scale study of subsidized psychoanalysis and long-term psychotherapy. More than 400 people in various phases, before, during and after subsidized psychoanalysis or long-term psychodynamic psychotherapy, were followed up for a period of three years with personal interviews, questionnaires and official statistics. Our analyses revealed progressive improvement the longer patients were in treatment--impressively strong among patients in psychoanalysis--on self-rating measures of symptom distress and morale. Improvement, however, was equally weak in both groups on a self-rating measure of social relations. Dosage factors (treatment duration and session frequency in combination) partly accounted for the outcome differences between those referred to psychoanalysis and those referred to long-term psychotherapy. Attitudes and ideals among therapists and analysts concerning the goals and means of psychotherapy were also associated with patient outcome, although in rather complex ways. A significant part of the outcome differences between patients in psychoanalysis and in psychotherapy could be explained by the adoption, in a large group of therapists, of orthodox psychoanalytic attitudes that seemed to be counterproductive in the practice of psychotherapy but not in psychoanalysis. It is suggested that this effect may be a negative transfer of the psychoanalytic stance into psychotherapeutic practice and that this may be especially pronounced when the attitudes are not backed up by psychoanalytic training.

Drift correction for gas sensors using multivariate methods

Abstract: Drift is one of the most serious impairments afflicting gas sensors. It can be seen as a gradual change in the sensor response over a long period of time when the external conditions an constant. T ...

Downregulation of telomerase reverse transcriptase mRNA expression by wild type p53 in human tumor cells

Abstract: The p53 tumor suppressor protein inhibits the formation of tumors through induction of cell cycle arrest and/or apoptosis. In the present study we demonstrated that p53 is also a powerful inhibitor of human telomerase reverse transcriptase (hTERT), a key component for telomerase. Activation of either exogenous temperature-sensitive (ts) p53 in BL41 Burkitt lymphoma cells or endogenous wild type (wt) p53 at a physiological level in MCF-7 breast carcinoma cells triggered a rapid downregulation of hTERT mRNA expression, independently of the induction of the p53 target gene p21. Co-transfection of an hTERT promoter construct with wt p53 but not mutant p53 in HeLa cells inhibited the hTERT promoter activity. Furthermore, the activation of the hTERT promoter in Drosophila Schneider SL2 cells was completely dependent on the ectopic expression of Sp1 and was abrogated by wt p53. Finally, wt p53 inhibited Sp1 binding to the hTERT proximal promoter by forming a p53-Sp1 complex. Since activation of telomerase, widely observed in human tumor cell lines and primary tumors, is a critical step in tumorigenesis, wt p53-triggered inhibition of hTERT/telomerase expression may reflect yet another mechanism of p53-mediated tumor suppression. Our findings provide new insights into both the biological function of p53 and the regulation of hTERT/telomerase expression.

Microflora‐associated characteristics in faeces from allergic and nonallergic infants

Abstract: Background The prevalence of allergic diseases has increased particularly over the past 30-40 years. A reduced microbial stimulation during infancy may result in a development of a disturbed balance between Th1- and Th2-like immunity. The gut flora is, quantitatively, the most important source for such stimulation. Objective The aim of the study was to compare the gut microbial flora in 25 allergic and 47 nonallergic 13-month-old infants (range 11-18), through analysing microflora-associated biochemical markers in faeces. Methods Microflora associated characteristics (MACs) were assessed by determining the concentrations of eight different short chain fatty acids and the conversion of cholesterol to coprostanol by gas chromatography. Faecal tryptic activity was analysed spectrophotometrically. Results The allergic infants had lower levels of propionic, i-butyric, butyric, i-valeric and valeric acid. In contrast, they had higher levels of the rarely detected i-caproic acid, which has been associated with the presence of Clostridium difficile. Furthermore, the allergic infants had higher relative distribution of acetic and i-caproic acid. None of the other parameters differed between the groups. Conclusion The results demonstrate differences in the MACs between allergic and nonallergic infants, indicating differences in the composition of the gut flora. that may disturb the development of a normal Th1-/Th2-balance in allergic children.

Frequent good partial remissions from thalidomide including best response ever in patients with advanced refractory and relapsed myeloma.

Abstract: Twenty-three patients with advanced and heavily pretreated myeloma were treated with thalidomide. Starting dose was 200 mg/d, and 20 patients had dose escalations up to 400 (n = 5), 600 (n = 12) or 800 mg/d (n = 3), usually in divided doses. Nineteen patients were refractory to recent chemotherapy, and four had untreated relapse after prior intensive therapy. Ten out of 23 patients (43%) achieved partial response (PR, nine with refractory and one with relapsed disease), six patients had minor response or stabilization of the disease and four had disease progression. Another three patients died early from advanced myeloma at less than 3 weeks of thalidomide therapy. Of the 10 patients with PR, seven had a better response than after any prior therapy, despite vincristine-doxorubicin-dexamethasone (VAD)-based treatment in all but one and high-dose melphalan with autologous stem cell support in four. Time to achieve PR was rapid in patients receiving thalidomide in divided doses (median 31 d). Responses also included reduced bone marrow plasma cell infiltration and improved general status. Normalized polyclonal gammaglobulin levels were seen in four cases. Six out of 10 patients with PR remained in remission with a median time on treatment of 23 weeks (range 15- 50 weeks). Sedation was common but usually tolerable, and some patients continued full- or part-time work. Four patients had skin problems, three patients had pneumonia, one hypothyrosis, one sinus bradycardia and one minor sensory neuropathy. Thalidomide may induce good partial remissions in advanced refractory myeloma with tolerable toxicity, and should be evaluated in other settings for myeloma patients. Divided thalidomide doses seem to reduce time to achieve remission and may improve response rate.

Photoluminescence quenching at a polythiophene/C-60 heterojunction

Abstract: Quenching of photoluminescence in a substituted polythiophene in the presence of a deposited C-60 layer is studied by steady-state and time-resolved photoluminescence (PL). The steady-state PL is evaluated by con -sidering the interference of the absorbed and emitted electro-optical field in the thin film coupled to exciton diffusion in the conjugated polymer. PL quenching occurs for excitons generated within 5 nm from the heterojunction. A blueshift of the polymer emission spectrum is observed when C-60 is deposited on top of a polymer thin film. The blueshift is shown to be caused by PL quenching before the excitation is transferred to the lowest-energy sites.

Neonatal end-of-life decision making: Physicians' attitudes and relationship with self-reported practices in 10 European countries.

Abstract: ContextThe ethical issues surrounding end-of-life decision making for infants with adverse prognoses are controversial. Little empirical evidence is available on the attitudes and values that underlie such decisions in different countries and cultures.ObjectiveTo explore the variability of neonatal physicians' attitudes among 10 European countries and the relationship between such attitudes and self-reported practice of end-of-life decisions.Design and SettingSurvey conducted during 1996-1997 in 10 European countries (France, Germany, Italy, the Netherlands, Spain, Sweden, the United Kingdom, Estonia, Hungary, and Lithuania).ParticipantsA total of 1391 physicians (response rate, 89%) regularly employed in 142 neonatal intensive care units (NICUs).Main Outcome MeasuresScores on an attitude scale, which measured views regarding absolute value of life (score of 0) vs value of quality of life (score of 10); self-report of having ever set limits to intensive neonatal interventions in cases of poor neurological prognosis.ResultsPhysicians more likely to agree with statements consistent with preserving life at any cost were from Hungary (mean attitude scores, 5.2 [95% confidence interval {CI}, 4.9-5.5]), Estonia (4.9 [95% CI, 4.3-5.5]), Lithuania (5.5 [95% CI, 4.8-6.1]), and Italy (5.7 [95% CI, 5.3-6.0]), while physicians more likely to agree with the idea that quality of life must be taken into account were from the United Kingdom (attitude scores, 7.4 [95% CI, 7.1-7.7]), the Netherlands (7.3 [95% CI, 7.1-7.5]), and Sweden (6.8 [95% CI, 6.4-7.3]). Other factors associated with having a pro–quality-of-life view were being female, having had no children, being Protestant or having no religious background, considering religion as not important, and working in an NICU with a high number of very low-birth-weight newborns. Physicians with scores reflecting a more quality-of-life view were more likely to report that in their practice, they had set limits to intensive interventions in cases of poor neurological prognosis, with an adjusted odds ratio of 1.5 (95% CI, 1.3-1.7) per unit change in attitude score.ConclusionsIn our study, physicians' likelihood of reporting setting limits to intensive neonatal interventions in cases of poor neurological prognosis is related to their attitudes. After adjusting for potential confounders, country remained the most important predictor of physicians' attitudes and practices.