UK PID Patients: Overview of perception on IgRT and infections using short survey.

Immunoglobulin replacement therapy (IgRT) has advanced over the years and is used to treat many patients with primary immunodeficiencies reducing the number of infections and the burden of disease. We investigated the perception of IgRT in two patient groups (UKPIPS and PID UK) and their condition through a short survey. The survey was a multiple-choice short survey consisting of 20 questions completed either online or on paper. Data analysis was performed using SAS analysis software using regression analysis, correlation analysis and t-tests. Statistical significance was considered with p<0.05. 278 surveys were analysed which showed that the majority of participants were satisfied with the immunoglobulin therapy they received (n=225, 80.9%). However, there was a small but significant number of participants (n=19, 6.9%) that still experienced severe and very severe infections despite adequate IgRT. 236 (84.9%) participants reported limitations in daily life due to infections. The dissatisfied participants (n=55, 18.3%) had more non-routine visits to healthcare providers, higher numbers of antibiotic treatments and more days absent from school, work, university or equivalent than the satisfied participants.

Towards a Field-Portable Real-Time Organic and Elemental Carbon Monitor.

Diesel particulate matter (DPM) has been classified as a carcinogen to humans by the International Agency for Research on Cancer. As a result of its potential carcinogenic nature, DPM exposure is regulated by the Mine Safety and Health Administration. Currently, diesel emissions in the workplace are monitored by collecting the aerosol onto filters, which are then sent to a laboratory for thermal-optical analysis using the NIOSH method 5040. This process can take days or even weeks, and workers can potentially be exposed to excessive levels of DPM before the problem is identified. Moreover, the delay involved in getting the loaded filter to the lab inevitably means the loss of some of the more volatile organic carbon. To remedy this delay, researchers from the National Institute for Occupational Safety and Health are seeking to develop a field-portable, real-time method for measuring elemental and organic carbons in DPM aerosols. In the current study, the use of mid-infrared spectrometry was investigated. It is believed that mid-infrared spectroscopy is more suitable for use in a real-time field-portable device than thermo-optical analysis methods. This article presents a method for measuring organic carbon (OC) and elemental carbon (EC) in DPM for a broad range of OC/EC ratios. The method has been successfully applied to laboratory-generated and mine samples.

Open-path FT-IR spectrometry: is completely unattended operation feasible?

Most protocols used for open-path Fourier transform infrared spectrometry (OP/FT-IR) require that spectra be measured at a resolution of 1 cm(-1) and that the concentrations of the analytes be calculated by classical least squares regression (CLS). These specifications were largely developed for monitoring light molecules with easily resolvable rotational fine structure. For most volatile organic compounds in air, the rotational fine structure is not resolvable and better accuracy can be obtained when the spectrum is measured at lower resolution (typically 8 cm(-1)), provided that the algorithm used for quantification is partial least squares regression (PLS). By measuring the spectrum at low resolution, the need for a liquid-nitrogen-cooled mercury cadmium telluride detector is reduced and a pyroelectric detector operating at ambient temperature can be used instead. By using PLS rather than CLS, spectral features due to water vapor do not have to be compensated and a short-path background spectrum can be used, greatly simplifying field measurements.

Application of multilayer feed-forward neural networks to automated compound identification in low-resolution open-path FT-IR spectrometry.

A drawback of current open-path Fourier transform infrared (OP/FT-IR) systems is that they need a human expert to determine those compounds that may be quantified from a given spectrum. In this work, multilayer feed-forward neural networks with one hidden layer were used to automatically recognize compounds in an OP/FT-IR spectrum without compensation of absorption lines due to atmospheric H2O and CO2. The networks were trained by fast-back-propagation. The training set comprised spectra that were synthesized by digitally adding randomly scaled reference spectra to actual open-path background spectra measured over a variety of path lengths and temperatures. The reference spectra of 109 compounds were used to synthesize the training spectra. Each neural network was trained to recognize only one compound in the presence of up to 10 other interferences in an OP/FT-IR spectrum. Every compound in a database of vaporphase reference spectra can be encoded in an independent neural network so that a neural network library can be established. When these networks are used for the identification of compounds, the process is analogous to spectral library searching. The effect of learning rate and band intensities on the convergence of network training was examined. The networks were successfully used to recognize five alcohols and two chlorinated compounds in field-measured controlled-release OP/FT-IR spectra of mixtures of these compounds.

Quantitative investigation of matrices for diffuse reflectance infrared Fourier transform spectrometry.

Five materials were investigated for use as diluent matrices for diffuse reflectance infrared Fourier transform (DRIFT) spectrometry of powdered samples. DRIFT spectra of powdered carbazole dispersed in germanium, silicon, diamond, potassium chloride and a chalcogenide glass were compared. Three particle size ranges were investigated for five concentrations of carbazole ranging from 0.1-10%. The effects of particle size and refractive index of the matrix are discussed.

Differential-polarization dual-beam FT-IR spectrometer for surface analysis.

A new system for reflection-absorption Fourier transform infrared spectroscopy is described. It is based on an optical subtraction of the two output beams of a cube-corner interferometer, which are recombined, orthogonally polarized and passed onto a single detector, where only the difference signal of the two components is detected. The dynamic range of the signal is thereby reduced by at least an order of magnitude. Owing to the cube-corner reflectors the dual-beam optics are relatively simple and readily convertible for operation in the conventional single-beam mode. First results with an incompletely optimized system show high photometric accuracy and equal signal-to-noise ratio compared to the single-beam operation. Methods for further improving its performance are proposed.

Pressure and temperature dependence of the self-broadened linewidths of the carbon dioxide laser bands.

The results of laboratory measurements of high-resolution infrared spectra of carbon dioxide in the region near 10 microm at several temperatures and pressures are described. Spectra of the CO(2) laser bands centered at 961 and 1064 cm(-1) were collected at a resolution ofO005 cm(-1) with the gas at temperatures between 50 and 150 degrees C. The self-broadened rotation-vibration line shapes were modeled using a nonlinear least-squares regression technique. Careful attention was given to the problem of base line correction. The temperature exponent of the pressure-broadening coefficient was estimated for thirty lines. The linewidths obtained previously using indirect methods compare well to data obtained in the present investigation.

Fourier transform infrared spectrometry.

The theory and instrumentation for Fourier transform infrared spectrometry are discussed. These instruments measure infrared spectra of the same quality as spectra measured on grating spectrometers in about one thousandth of the time. Their sensitivity advantage for spectra measured in equal times is between a factor of 10 and 100. Commercial spectrometers are now available from nine vendors in North America. Important areas of chemistry include atmospheric monitoring, surface chemistry, and on-line identification of chromatographically separated materials. Many new biochemical and biomedical applications are also becoming apparent, including investigations of phase transitions in lipids and studies of the biocompatibility of implant polymers.

Temperature dependence of the self-broadening coefficients for the fundamental band of carbon monoxide.

The exponent eta for the temperature dependence of the self-broadening coefficient of carbon monoxide has been measured directly using a tunable diode laser spectrometer. For lines of (12)C(16)O between P(25) and P(31), the exponent has a value of 0.66 +/- 0.05. For the P(13) and P(16) lines of (13)C(16)O, the exponent appears to be the same. These results show that the value of eta is less than the generally accepted value of 0.75 for temperatures between ambient and 180 degrees C.

Fourier transform infrared spectroscopy: recent developments.

The 1977 International Conference on Fourier Transform Infrared Spectroscopy was held 20-24 June 1977 at Columbia, S.C. The manuscripts of most of the invited speakers at this meeting follow this report. This paper summarizes the seven papers in this category which could not be submitted. These papers described the application of cryogenic interferometers to atmospheric sounding (Stair), to the measurement of cosmic background radiation (Richards), and to the study of chemical reaction dynamics (McDonald). The use of ultrasensitive far infrared detectors for studying the properties of solids was described by Sievers. Genzel and Griffiths described applications of the optical subtraction technique for far infrared and mid infrared measurements, respectively. Finally Wyntjes summarized his views on the present and future of interferometry.