EMI Reduction in an Interleaved Buck Converter Through Spread Spectrum Frequency Modulation

Spread spectrum frequency modulation is applied in a high-frequency DC/DC power converter to reduce conducted EMI. A new modulation biasing technique is developed to further reduce EMI levels in converters equipped with hardware filters. In the lab, this biasing shows effective shaping of the EMI spectrum

Aspects of peripheral thyroid hormone metabolism

The research into thyroid function has a long history. The recognition of goiter as pathology of the thyroid gland dates back to the ancient world of Rome and Greece and possibly even to the early history of chinese medicine. In an excellent review of the historical aspects of the discovery of thyroid hormones and their biological action (1) Pitt-Rivers describes the growing awareness of the significance of iodine for thyroid function early in the 19th century. The actual presence of organic iodine in the thyroid gland was demonstrated for the first time in 1896 by Baumann who called his concentrate of a thyroid extract "Iodothyrin". In 1914 Kendall isolated a crystalline material from thyroid hydrolysates and named it "Thyroxin" after thyroxindole, since he believed this sUbstance to be an indole derivative. The compound proved to have biological activity in hypothyroid man and aninals. The actual structure fonnula of the thyroxine rrolecule was disclosed by Harington in 1926. Only in 1952 the existence of 3,3' ,5-triiodothyronine was simultaneously demonstrated in beef thyroid and human serum by Gross and Pitt-Rivers and in rat thyroid by Roche et al. At the same time it appeared that this triiodothyronine was about three times as potent as thyroxine in the goiter prevention assay in rats. The original postulate by Gross and Pitt-Rivers (1953) that triiodothyronine originates by degradation of thyroxine in peripheral tissues and constitutes the principal active thyroid hormone was established by Sterling and Braverman in as late as 1970. Since this time thyroid research has explosively expanded in many fields, such as thyroidal synthesis and secretion of iodothyronines, feedback regulations of the hypothalamic-pituitary-thyroid axis, goiter etiology and autoimmune rrechanisrns with associated hyper- and hyperthyroidism, thyroid cancer, vascular transport proteins, nuclear thyroid hormone receptors with post-receptor biological effects and the broad field of peripheral thyroid honnone rnetabolism. This last subject in its turn can be subdivided into smaller areas, such as kinetic studies with isotope labeled thyroid hormones ,the processes involved in membrane transport, as well as the subcellular distribution of either locally produced or plasma-bome iodothyronines. But also, and this represents an important section in this tllesis, the intracellular metabolism of the m.lltiple thyroxine- derived metabolites. It is obvious that the above list is far from complete, but it gives an irrpression of the wide scope of current thyroid research. This thesis is a compilation of various investigations in the field of peripheral thyroid horrrone metabolism. The rrain objective of the presented work has been to obtain rrore kno.vledge about the physiology of the various metabolic pathways of iodothyronines. This objective was chosen in the hope to contribute to a better understanding of the complex metabolic adaptations in iodothyronine :metabolism, known to be induced by several drugs, dietary changes or diseases. At first sight the rather diverse subjects of investigation in Section II of this thesis bear no apparent relation

Outcome of pulmonary rehabilitation in COPD patients with severely impaired health status

Introduction: Effects of pulmonary rehabilitation (PR) in chronic obstructive pulmonary disease (COPD) patients with severely impaired health status are poorly documented since these patients are usually excluded from clinical trials. This retrospective, observational study aims to study the impact of disease on health status and the effects of PR on COPD patients referred to a tertiary center for PR in The Netherlands. Methods: Between June 2006 and June 2010, 437 patients with COPD were allocated to our intensive, comprehensive PR program. Patients participated in this interdisciplinary program for 12 weeks for a weekly average of 20-25 hours. Before and directly after, several measures of physical performance and health-related quality of life were determined. Results: At baseline, most patients (75%) had a Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage of III-IV. Peak exercise performance on a cycle ergometer was on average reduced to 43 ± 29 Watt, and health-related quality of life was significantly impaired, with a total score on the St George's Respiratory Questionnaire (SGRQ) of 66. Health-care utilization in the year preceding PR was very high. After rehabilitation, all outcome measures improved statistically significantly (P <, 0.001). Exercise performance measured with the 6 minute walking distance test improved clinically significantly in 68% of the patients, whereas 75% of the patients showed a clinically meaningful improvement in quality of life as measured with the SGRQ. Multiple regression analysis revealed that 19% of the variation in responses on the 6 minute walking distance test and the SGRQ could be explained on the basis of baseline characteristics. Conclusion: The present study provides data to indicate that COPD patients may substantially benefit from rehabilitation in a tertiary pulmonary rehabilitation center, despite a severely impaired health status and high level of health-care utilization, in which prior treatment in primary and secondary care have failed to improve health status. Individual rehabilitation responses can only partially be predicted on the basis of baseline characteristics. Consequently, no firm conclusions can be drawn from this study with respect to the selection of candidates that could be deemed eligible for this rehabilitation program when entering the program

Search for Rayleigh scattering in the atmosphere of GJ1214b

We investigate the atmosphere of GJ1214b, a transiting super-Earth planet with a low mean density, by measuring its transit depth as a function of wavelength in the blue optical portion of the spectrum. It is thought that this planet is either a mini-Neptune, consisting of a rocky core with a thick, hydrogen-rich atmosphere, or a planet with a composition dominated by water. Most observations favor a water-dominated atmosphere with a small scale-height, however, some observations indicate that GJ1214b could have an extended atmosphere with a cloud layer muting the molecular features. In an atmosphere with a large scale-height, Rayleigh scattering at blue wavelengths is likely to cause a measurable increase in the apparent size of the planet towards the blue. We observed the transit of GJ1214b in the B-band with the FOcal Reducing Spectrograph (FORS) at the Very Large Telescope (VLT) and in the g-band with both ACAM on the William Hershel Telescope (WHT) and the Wide Field Camera (WFC) at the Isaac Newton Telescope (INT). We find a planet-to-star radius ratio in the B-band of 0.1162+/-0.0017, and in the g-band 0.1180+/-0.0009 and 0.1174+/-0.0017 for the WHT & INT observations respectively. These optical data do not show significant deviations from previous measurements at longer wavelengths. In fact, a flat transmission spectrum across all wavelengths best describes the combined observations. When atmospheric models are considered a small scale-height water-dominated model fits the data best.Comment: Accepted for publication in Ap

The Current Status of Immune Checkpoint Inhibitors in Neuro-Oncology:A Systematic Review

The introduction of immune checkpoint inhibitors (ICI), as a novel treatment modality, has transformed the field of oncology with unprecedented successes. However, the efficacy of ICI for patients with glioblastoma or brain metastases (BMs) from any tumor type is under debate. Therefore, we systematically reviewed current literature on the use of ICI in patients with glioblastoma and BMs. Prospective and retrospective studies evaluating the efficacy and survival outcomes of ICI in patients with glioblastoma or BMs, and published between 2006 and November 2019, were considered. A total of 88 studies were identified (n = 8 in glioblastoma and n = 80 in BMs). In glioblastoma, median progression-free (PFS) and overall survival (OS) of all studies were 2.1 and 7.3 months, respectively. In patients with BMs, intracranial responses have been reported in studies with melanoma and non-small-cell lung cancer (NSCLC). The median intracranial and total PFS in these studies were 2.7 and 3.0 months, respectively. The median OS in all studies for patients with brain BMs was 8.0 months. To date, ICI demonstrate limited efficacy in patients with glioblastoma or BMs. Future research should focus on increasing the local and systemic immunological responses in these patients

Age-dependent differences in diabetes and acute hyperglycemia between men and women with ST-elevation myocardial infarction: a cohort study

BACKGROUND: Both acute hyperglycemia as diabetes results in an impaired prognosis in ST-elevation myocardial infarction (STEMI) patients. It is unknown whether there is a different prevalence of diabetes and acute hyperglycemia in men and women within age-groups. METHODS: Between 2004 and 2010, 4640 consecutive patients (28% women) with STEMI, were referred for primary PCI. Patients were stratified into two age groups, < 65 years (2447 patients) and ≥65 years (2193 patients). Separate analyses were performed in 3901 patients without diabetes. Diabetes was defined as known diabetes or HbA1c ≥6.5 mmol/l at admission. RESULTS: The prevalence of diabetes was comparable between women and men in the younger age group (14% vs 12%, p = 0.52), whereas in the older age group diabetes was more prevalent in women (25% vs 17% p < 0.001). In patients without diabetes, admission glucose was comparable between both genders in younger patients (8.1 ± 2.0 mmol/l vs 8.0 ± 2.2 mmol/l p = 0.36), but in older patients admission glucose was higher in women than in men (8.7 ± 2.1 mmol/l vs 8.4 ± 2.1 mmol/l p = 0.028). After multivariable analyses, the occurrence of increased admission glucose was comparable between men and women in the younger age group (OR 1.1, 95%CI 0.9-1.5), but increased in women in the older age group (OR 1.3, 95% CI 1.1-1.7). Both diabetes and hyperglycemia were associated with a higher one-year mortality in both men and women. CONCLUSIONS: The differences between men and women in hyperglycemia and diabetes in patients with STEMI are age dependent and can only be observed in older patients. This may have implications for medical treatment and should be investigated further

DIRECT trial. Diverticulitis recurrences or continuing symptoms: Operative versus conservative Treatment. A MULTICENTER RANDOMISED CLINICAL TRIAL

Background: Persisting abdominal complaints are common after an episode of diverticulitis treated conservatively. Furthermore, some patients develop frequent recurrences. These two groups of patients suffer greatly from their disease, as shown by impaired health related quality of life and increased costs due to multiple specialist consultations, pain medication and productivity losses. Both conservative and operative management of patients with persisting abdominal complaints after an episode of diverticulitis and/or frequently recurring diverticulitis are applied. However, direct comparison by a randomised controlled trial is necessary to determine which is superior in relieving symptoms, optimising health related quality of life, minimising costs and preventing diverticulitis recurrences against acceptable morbidity and mortality associated with surgery or the occurrence of a complicated recurrence after conservative management. We, therefore, constructed a randomised clinical trial comparing these two treatment strategies. Methods/design: The DIRECT trial is a multicenter randomised clinical trial. Patients (18-75 years) presenting themselves with persisting abdominal complaints after an episode of diverticulitis and/or three or more recurrences within 2 years will be included and randomised. Patients randomised for conservative treatment are treated according to the current daily practice (antibiotics, analgetics and/or expectant management). Patients randomised for elective resection will undergo an elective resection of the affected colon segment. Preferably, a laparoscopic approach is used. The primary outcome is health related quality of life measured by the Gastro-intestinal Quality of Life Index, Short-Form 36, EQ-5D and a visual analogue scale for pain quantification. Secondary endpoints are morbidity, mortality and total costs. The total follow-u

Het rijdende pontveer in Nigtevecht

Het Oude foto met bijschrift. Het pontveer heeft 15 jaar dienst gedaan en wel van 1952 tot 31 december 196

Inappropriate prescription of proton pump inhibitors on two pulmonary medicine wards

Objective We recently noticed that proton pump inhibitor (PPI) use was high on a pulmonary medicine ward of a university clinic and reasons for this high usage were not clear. Our aim was to determine the indications for PPI use on two pulmonary medicine wards and to assess whether this use was appropriate. Methods We assessed prospectively the number of patients on PPIs and the indications for PPI use on two pulmonary medicine wards, one from a university and one from a regional clinic in The Netherlands. Results On admission, 88 of 300 (29%) patients already used PPIs. The use of PPIs was discontinued in three (1%) patients, whereas PPIs were initiated in 45 (15%) patients, resulting in 130 (43%) patients on PPIs during hospitalization. The most common indication for PPI use was the prevention of medication-associated complications. In 78 of 130 (60%) patients on PPIs, this medication was used for a registered indication, whereas in 52 (40%) patients a registered indication was not present (overuse). In contrast, 19 of 300 (6%) patients were not prescribed PPIs despite the presence of a registered indication for its use (underuse). No differences were found in prescription rate and indications for PPI use between the university and the regional clinic. Conclusion PPI use was very common on two pulmonary medicine wards in the Netherlands. Forty percent of the patients used their PPIs for a nonregistered indication. As use of PPIs is costly and may be associated with side effects, hospital physicians should to be better educated on guidelines for its use