On the Hierarchical Preconditioning of the PMCHWT Integral Equation on Simply and Multiply Connected Geometries

We present a hierarchical basis preconditioning strategy for the Poggio-Miller-Chang-Harrington-Wu-Tsai (PMCHWT) integral equation considering both simply and multiply connected geometries.To this end, we first consider the direct application of hierarchical basis preconditioners, developed for the Electric Field Integral Equation (EFIE), to the PMCHWT. It is notably found that, whereas for the EFIE a diagonal preconditioner can be used for obtaining the hierarchical basis scaling factors, this strategy is catastrophic in the case of the PMCHWT since it leads to a severly ill-conditioned PMCHWT system in the case of multiply connected geometries. We then proceed to a theoretical analysis of the effect of hierarchical bases on the PMCHWT operator for which we obtain the correct scaling factors and a provably effective preconditioner for both low frequencies and mesh refinements. Numerical results will corroborate the theory and show the effectiveness of our approach

Orthogonal frequency division multiplexing with amplitude shift keying subcarrier modulation as a reliable and efficient transmission scheme for self-mixing receivers

A new receiving scheme for self-mixing receivers is presented that overcomes the disadvantages of the self-heterodyne concept. Generally speaking, the self-mixing receiver offers immunity to phase noise and frequency offsets, especially at very high frequencies, since it does not require radio frequency local oscillators. Our proposed technique eliminates the drawbacks of the self-heterodyne transmission scheme, which are the poor power efficiency and the strong dependence on the continously transmitted carrier. A nonlinear system of equations is constructed that describes a phase retrieval problem for the reconstruction of the original transmit signal before self-mixing. Two different solution strategies, with restrictions in time and frequency domain, are presented. As a consequence, the self-mixing equation system is shown to be solvable with some a-priori information about the transmit signal. With this novel approach, the transmitted information is distributed over the full available bandwidth, and there is no special dependence on a certain subcarrier for the down-conversion. The general performance, regarding bit error ratio over signal to noise ratio, is improved by at least 2 dB as compared to the self-heterodyne transmission scheme. In the case of frequency selective channels, e.g. multi-path propagation, this improvement is shown to be much larger, because the presented approach is able to reconstruct the received subcarriers without the necessity of receiving all subcarriers

The association between prescription change frequency, chronic disease score and hospital admissions: a case control study

BACKGROUND: The aim of this study was to assess the association between prescription changes frequency (PCF) and hospital admissions and to compare the PCF to the Chronic Disease Score (CDS). The CDS measures comorbidity on the basis of the 1-year pharmacy dispensing data. In contrast, the PCF is based on prescription changes over a 3-month period. METHODS: A retrospective matched case–control design was conducted. 10.000 patients were selected randomly from the Dutch PHARMO database, who had been hospitalized (index date) between July 1, 1998 and June 30, 2000. The primary study outcome was the number of prescription changes during several three-month time periods starting 18, 12, 9, 6, and 3 months before the index date. For each hospitalized patient, one nonhospitalized patient was matched for age, sex, and geographic area, and was assigned the same index date as the corresponding hospitalized patient. We classified four mutually exclusive types of prescription changes: change in dosage, switch, stop and start. RESULTS: The study population comprised 8,681 hospitalized patients and an equal number of matched nonhospitalized patients. The odds ratio of hospital admission increased with an increase in PCF category. At 3 months before the index date from PCF=1 OR 1.4 [95% CI 1.3-1.5] to PCF= 2–3 OR 2.2 [95% CI 1.9-2.4] and to PCF ≥ 4 OR 4.1 [95% CI 3.1-5.1]. A higher CDS score was also associated with an increased odds ratio of hospitalization: OR 1.3 (95% CI 1.2-1.4) for CDS 3–4, and OR 3.0 (95% CI 2.7-3.3) for CDS 5 or higher. CONCLUSION: The prescription change frequency (PCF) is associated with hospital admission, like the CDS. Pharmacists and other healthcare workers should be alert when the frequency of prescription changes increases. Clinical rules could be helpful to make pharmacists and physicians aware of the risk of the number of prescription changes

Comparison of non-convex cost functionals for the consideration of phase differences in phaseless near-field far-field transformations of measured antenna fields

This work introduces two methods which extend the non-convex minimization problem arising in phaseless (NF) far-field (FF) transformations. With the new extensions, knowledge about phase differences between measurement points can be incorporated into the minimization problem. The additional information helps to avoid stationary points of the minimization cost functional which would otherwise compromise the result of the near-field far-field transformation. The methods are incorporated into the Fast Irregular Antenna Field Transformation Algorithm (FIAFTA), analyzed and compared. Their effectiveness is shown by transforming synthetic near-field data sets with partial knowledge of phase differences to the far-field

Interdigital Resonators in Wideband Ridged-Waveguide Filters

An interdigital resonator approach for wideband filter applications in ridged-waveguide technology is presented. The interdigital arrangement of the ridged-waveguide resonators ensures stronger coupling between the resonators. As the coupling sections are consequently enlarged by the interdigital arrangement of the resonators, more feasible filter structures are possible at increasing frequencies. The approach itself can be easily implemented with conventional filter synthesis formulas, which is demonstrated by two 20 GHz examples with a bandwidth of 2 GHz and 100 MHz, respectively. The designed filters are subsequently compared to the standard implementation of ridged-waveguide filters.</p

Measurement and transformation of continuously modulated fields using a short-time measurement approach

Near-field measurements, which are performed in-situ, may suffer from the fact that the antenna under test (AUT) cannot be accessed to transmit or receive a specifically tailored test signal. In some scenarios, it might also be desired to test the AUT during its real operation state, especially when it comes to the verification of antenna systems. Therefore, the need to handle time- and space-modulated fields in combination with a time-harmonic near-field to far-field transformation (NFFFT) arises. For the case where unmanned aerial vehicles (UAVs) carry the field probe in in-situ measurement scenarios, long observation times, required for the resolution of the frequency spectra of modulated fields, are detrimental due to the UAV movement resulting in blurred measurement positions. The short-time measurement (STM) approach, presented in this article, offers a way to transform the measured field data using a time-harmonic NFFFT with short observation times for the collection of the individual field samples. Measurements are shown which demonstrate the applicability of the STM approach for the measurement and transformation of continuously time-modulated fields in different measurement scenarios.</p

Association between HTR2C polymorphisms and weight loss in obese patients

OBJECTIVE To investigate whether the HTR2C rsUU334 and 759 C/T polymorphisms are associated with weight loss in an anti- obesity programme. DESIGN AND METHODS A longitudinal observational follow-up study was used to assess the association between HTR2C genotypes and weight loss during a nine month programme in an obesity clinic. Caucasian patients aged 18 years or older were included. Data were extracted from the patients' medical records. In total, 128 patients were included 129 males). RESULTS There was a significant association between the HTR2C 759 T allele and resistance to weight loss in the first month of the programme. For each T allele present, there was 0.78% (95% confidence interval [95%-CI] 0.19-1.38; P = 0.011 less weight loss (as a percentage of the body weight at start). Patients carrying the variant HTR2C 759 T allele were also less likely to reach > 7% weight loss (odds ratio [OR] 0.23; 95%-CI 0.06- 0,85; P = 0.028), and dropped out of the programme sooner [-0.78 months; 95%-CI -1.51- -0.06; P = 0.035; corrected for gender). No associations with the HTR2C rsUU334- genotype and any of the primary endpoints for weight loss or secondary endpoints were found. CONCLUSION Patients carrying the HTR2C 759 T allele were more resistant to weight loss and dropped out of the programme sooner. However, these effects were small and only explained a small part of a very complex puzzle. Genotyping HTR2C to predict a patient's chance of success in an obesity clinic is therefore not warranted

Partially polarized physical optics

peer reviewe

Medication self-management: Considerations and decisions by older people living at home

Background: Medication self-management is complicated for older people. Little is known about older persons’ considerations and decisions concerning medication therapy at home. Objective: (s): To explore how older people living at home self-manage their medication and what considerations and decisions underpin their medication self-management behavior. Methods: Semi-structured interviews with consenting participants (living at home, aged ≥65, ≥5 different prescription medications daily) were recorded and transcribed with supporting photographs. Content was analyzed with a directed approach and presented according to three phases of medication self-management (initiation, execution, and discontinuation). Results: Sixty people were interviewed. In the initiation phase, participants used different techniques to inform healthcare professionals and to fill and check prescriptions. Over-the-counter medication was seldom discussed, and potential interactions were unknown to the participants. Some participants decided to not start treatment after reading the patient information leaflets for fear of side effects. In the execution phase, participants had various methods for integrating the use of new and chronic medication in daily life. Usage problems were discussed with healthcare professionals, but side effects were not discussed, since the participants were not aware that the signs and symptoms of side effects could be medication-related. Furthermore, participants stored medication in various (sometimes incorrect) ways and devised their own systems for ordering and filling repeat prescriptions. In the discontinuation phase, some participants decided to stop or change doses by themselves (because of side effects, therapeutic effects, or a lack of effect). They also mentioned different considerations regarding medication disposal and disposed their medication (in)correctly, stored it for future use, or distributed it to others. Conclusions: Participants’ considerations and decisions led to the following: problems in organizing medication intake, inadequate discussion of medication-related information with healthcare professionals, and incorrect and undesirable medication storage and disposal. There is a need for medication self-management observation, monitoring, and assistance by healthcare professionals

Proposal of standardization to assess adherence with medication records: methodology matters

Medication adherence is the process by which patients take their medication as prescribed and is an umbrella term that encompasses all aspects of medication use patterns. Ambiguous terminology has emerged to describe a deviation from prescribed regimen, forcing the European ABC Project to define 3 phases of medication use: initiation, implementation, and discontinuation. However, different measures of medication adherence using medication records are currently available that do not always distinguish between these phases. The literature is lacking standardization and operationalization of the assessment methods.; To propose a harmonization of standards as well as definitions of distinct measures and their operationalization to quantify adherence to medication from medication records.; Group discussions and consensus process among all coauthors. The propositions were generated using the authors' experiences and views in the field of adherence, informed by theory.; The concepts of adherence measures within the new taxonomy were harmonized, and the standards necessary for the operationalization of adherence measures from medication records are proposed. Besides percentages and time-to values, the addition of a dichotomous value for the reinitiation of treatment is proposed. Methodological issues are listed that should be disclosed in studies on adherence.; The possible impact of the measures in adherence research is discussed. By doing this, the results of future adherence research should gain in accuracy. Finally, studies will become more transparent, enabling comparison between studies