Class-3c compression bandaging for venous ulcers: comparison of spiral and figure-of-eight techniques

Aim.  This paper reports a study to compare the differences in compression produced on a limb using a spiral and a figure-of-eight bandaging technique.Background.  Chronic leg ulcers are a major health problem in Western countries. Compression bandaging is the accepted treatment for venous leg ulcers. The spiral and the figure-of-eight techniques are traditional methods of applying compression bandages. but their performance in terms of pressure profiles is unknown. Despite a lack of evidence about technique, class-3c compression bandages are not currently recommended for application in a figure-of-eight as this is thought to produce dangerously high pressure.Methods.  A cross-over experimental design was used with a sample of 26 nurse bandagers. Consistency of performance was tested. Bandage stretch and overlap were measured and analysed by standard deviation to ensure that the techniques were consistent and repeatable. Pressure probes were then applied to the medial, posterior and lateral aspects of the lower limb of a healthy volunteer. The class-3c compression bandage was applied using both techniques and the pressure profiles around the leg were measured under the bandage. The results of each technique were compared using independent sample t-tests. The data were collected in 1999.Results.  The figure-of-eight technique provided statistically significantly higher compression at lower areas of the leg than the spiral technique. Mean pressure difference was 20·3 mmHg at the ankle, 22·2 mmHg at the gaiter, 9·4 mmHg at the calf. The pressure differences decrease towards the knee with both techniques and decrease more steeply with the figure-of-eight technique.Conclusion.  The spiral technique was a safe and comfortable method of bandage application. The figure-of-eight also provided graduated compression but with some high areas of pressure, notably overlying the Achilles tendon. However, before firm practice recommendations are made, replication of the study using a padding layer and a larger sample is needed

The QUBIC instrument for CMB polarization measurements

Measurements of cosmic microwave background (CMB) polarization may reveal the presence of a background of gravitational waves produced during cosmic inflation, providing thus a test of inflationary models. The Q&U Bolometric Interferometer for Cosmology (QUBIC) is an experiment designed to measure the CMB polarization. It is based on the novel concept of bolometric interferometry, which combines the sensitivity of bolometric detectors with the properties of beam synthesis and control of calibration offered by interferometers. To modulate and extract the input polarized signal of the CMB, QUBIC exploits Stokes polarimetry based on a rotating half-wave plate (HWP). In this work, we illustrate the design of the QUBIC instrument, focusing on the polarization modulation system, and we present preliminary results of beam calibrations and the performance of the HWP rotator at 300 K

Angular resolution at map level in the QUBIC instrument

Since its discovery in the 1960s, the cosmic microwave background (CMB) radiation has become a very important observational tool to understand the physics of the early universe. The parameter r, defined as the relative amplitude of tensor to scalar perturbations, is currently constrained to the range r < 0.056. QUBIC is a ground-based instrument designed to search for very weak B-mode signals in polarization anisotropies at intermediate angular scales (l 3c 30 12 200). To achieve this goal, QUBIC combines two widely used techniques in the CMB community: interferometry and bolometry. In this work, we compute the angular resolution for an end-to-end simulation using two independent methods: Fit and Sigma. We conclude that the reconstruction performed by the software is appropriate since the resolution measured with both calibrated methods coincides with the theoretical value of the expected resolution.Desde su descubrimiento en los a\u2dcnos 1960, el fondo c\ub4osmico de microondas (CMB, por sus siglas en ingl\ub4es) se ha convertido en una importante herramienta observacional para entender la f\ub4\u131sica del universo temprano. El par\ub4ametro r, definido como la amplitud de las perturbaciones tensoriales relativas a las escalares, est\ub4a acotado actualmente al rango r < 0.056. QUBIC es un instrumento terrestre dise\u2dcnado para buscar se\u2dcnales muy d\ub4ebiles de los modos B en las anisotrop\ub4\u131as de la polarizaci\ub4on a escalas angulares intermedias (l 3c 30 12 200). Para lograr este objetivo, QUBIC combina dos t\ub4ecnicas muy usadas en la comunidad CMB: interferometr\ub4\u131a y bolometr\ub4\u131a. En este trabajo calculamos la resoluci\ub4on angular de una simulaci\ub4on end-to-end con dos m\ub4etodos independientes: Fit y Sigma. Concluimos que la reconstrucci\ub4on que realiza el software es apropiada ya que la resoluci\ub4on medida con ambos m\ub4etodos calibrados coincide con los valores te\ub4oricos de la resoluci\ub4on esperada