414 research outputs found
Electromagnetic Waves in Variable Media
Two methods are explained to exactly solve Maxwell's equations where
permittivity, permeability and conductivity may vary in space. In the
constitutive relations, retardation is regarded. If the material properties
depend but on one coordinate, general solutions are derived. If the properties
depend on two coordinates, geometrically restricted solutions are obtained.
Applications to graded reflectors, especially to dielectric mirrors, to
filters, polarizers and to waveguides, plain and cylindrical, are indicated.
New foundations for the design of optical instruments, which are centered
around an axis, and for the design of invisibility cloaks, plain and spherical,
are proposed. The variability of material properties makes possible effects
which cannot happen in constant media, e.g. stopping the flux of
electromagnetic energy without loss. As a consequence, spherical devices can be
constructed which bind electromagnetic waves
Quality of provided care in vascular surgery : outcome assessment & improvement strategies
The aim of this thesis was to evaluate the quality of care in vascular surgery in end-stage renal disease (ESRD) and peripheral arterial occlusive disease (PAOD): intermittent claudication (IC) and critical lower limb ischaemia (CLI) patients. Therefore firstly it focused on the improvement of the quality of perioperative patient management concerning: (1) a systematic review concerning all quality initiatives in vascular surgery was conducted, (2) an assessed of the implementation of established recommended SP measures in patients with PAOD was established and (3) an evaluation of the implementation of a new optimised care protocol (OCP) outlined in a multidisciplinary meeting was done. Then, it further focused mainly on AEs (registration, occurrence, consequences) of PAOD patients. A (1) determination of risk factors for adverse events (AE) occurrence by assessing three different health care facilities was assessed, (2) an evaluation of the occurrence of cardiac AE after primary lower extremity arterial revascularization (LEAR) for CLI in order to evaluate the impact of cardiac AEs on the clinical outcome was done and (3) a calculation of the average estimated total costs of AEs after treatment for PAOD was performed. Furthermore, the thesis focussed on the quality of life (QOL) of PAOD patients after primary LEAR, concerning (1) the role of social support on the outcome and (2) the improvement of functional status after primary LEAR.Astra Zeneca BV Bard Benelux BV B. Braun Medical BV ChipSoft BV Cordis (Johnson & Johnson) Olympus Nederland BV Terumo BeNelux BVUBL - phd migration 201
Estimated impact of maternal vaccination on global paediatric influenza-related in-hospital mortality: A retrospective case series
Background: Influenza virus infection is an important cause of under-five mortality. Maternal vaccination protects children younger than 3 months of age from influenza infection. However, it is unknown to what extent paediatric influenza-related mortality may be prevented by a maternal vaccine since global age-stratified mortality data are lacking. Methods: We invited clinicians and researchers to share clinical and demographic characteristics from children younger than 5 years who died with laboratory-confirmed influenza infection between January 1, 1995 and March 31, 2020. We evaluated the potential impact of maternal vaccination by estimating the number of children younger than 3 months with in-hospital influenza-related death using published global mortality estimates. Findings: We included 314 children from 31 countries. Comorbidities were present in 166 (53%) children and 41 (13%) children were born prematurely. Median age at death was 8·6 (IQR 4·5-16·6), 11·5 (IQR 4·3-24·0), and 15·5 (IQR 7·4-27·0) months for children from low- and lower-middle-income countries (LMICs), upper-middle-income countries (UMICs), and high-income countries (HICs), respectively. The proportion of children younger than 3 months at time of death was 17% in LMICs, 12% in UMICs, and 7% in HICs. We estimated that 3339 annual influenza-related in-hospital deaths occur in the first 3 months of life globally. Interpretation: In our study, less than 20% of children is younger than 3 months at time of influenza-related death. Although maternal influenza vaccination may impact maternal and infant influenza disease burden, additional immunisation strategies are needed to prevent global influenza-related childhood mortality. The missing data, global coverage, and data quality in this study should be taken into consideration for further interpretation of the results. Funding: Bill & Melinda Gates Foundation
Het paracervicale block tijdens de baring
De baring is het enige fysiologische gebeuren dat met
pijn gepaard gaat. Dit wordt reeds aangeduid door het
Nederlandse woord 11wee" en equivalente woorden in vele
andere talen (dolor, douleur, pains, Wehe e.a.). De pijn
is aanvankelijk vooral gelocaliseerd in de onderbuik en
onder in de rug. In het laatste deel van de ontsluitingsperiade
en tijdens de uitdrijving wordt de pijn daarbij
ook in de bekkenbodem, de genitalia externa en het rectum
aangegeven. De pijn wordt door de barende zichtbaar en hoorbaar
tot uitdrukking gebracht door middel van motorische
onrust, woorden waarin wanhoop wordt uitgedrukt en vraag
naar verlossing (Buytendijk, 1943; van Eps, 1954). Volgens
van Eps (1954) en anderen moet de fysiologische pijn tijdens
de baring als ''wordingspijn'' worden onderscheiden van
de pathologische "verstoringspijn".
Er is slechts weinig onderzoek verricht naar factoren,
die het optreden en de ernst van baringspijn bepalen.
Zeker is wel, dat de pijnbeleving en de uitdrukking ervan
samenhangt met de psychische gesteldheid van de barende.
Deze psychische gesteldheid wordt in belangrijke mate gevormd
door opvoeding en culturele achtergrond (Crawford,
1972; Phillips, 1975; van Eps, 1954). De houding van de
zwangere ten opzichte van het toekomstige kind en de opvang
door de echtgenoot en de verloskundige ten tijde van
de baring zijn eveneens van belang. Behalve psychische
factoren zijn ook somatische invloeden van betekenis voor
de wijze waarop de baringspijn wordt beleefd en uitgedrukt
Symptomatic Atherosclerosis: the tip of the iceberg
Vascular surgery patients are at increased risk for developing adverse cardiac events, such as
myocardial ischemia or infarction, associated with postoperative morbidity and mortality.
Perioperative cardiac complications, therefore, remain an area of clinical interest and concern in
patients undergoing vascular surgery. Importantly, it has been demonstrated that the great
majority of cardiac events in vascular surgery patients are asymptomatic. The high frequency of
perioperative cardiac complications reflects the high prevalence of underlying coronary artery
disease. Surgical procedures can be classified to be associated with low-risk (<1%),
intermediate-risk (1-5%), or high-risk (>5%) for the development of perioperative cardiac
complications. Open lower extremity revascularization and open aortic procedures are
considered high-risk surgery. Carotid surgery and endovascular aortic aneurysm repair are
considered to have intermediate cardiac risk.
Over the years, perioperative risk assessment has evolved significantly in order to
detect surgical patients with myocardium at risk due to coronary artery disease. Several risk
indices have been developed to identify patients at risk, of which the Revised Cardiac Risk
index is currently widely used. Cardiac risk factors imbedded in the Revised Cardiac Risk index
are (i) ischemic heart disease, (ii) symptomatic heart failure, (iii) cerebrovascular disease, (iv)
insulin dependent diabetes mellitus, (v) renal dysfunction, and (vi) high-risk surgery. However,
preoperative risk stratification for adverse cardiac outcome using traditional cardiac risk indices
is considered suboptimal, indicating the necessity to improve cardiac evaluation before
surgery.
These days, the physician needs to inform the patient about his or her perioperative risk. When
preoperative risk stratification with, for instance, the use of the Revised Cardiac Risk index
identifies the patient to have an increased cardiac risk, additional cardiac testing to diagnose or
exclude coronary artery disease is warranted
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