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1.
Stellan Jacobsson Anders Lundgren Joakim Johansson 《International Journal of Infrared and Millimeter Waves》1990,11(11):1251-1261
Computer generated Fourier transform phase holograms, known as kinoforms, have been synthesized, manufactured and their performance evaluated at a wavelength of 3 mm (100 GHz). The kinoforms were synthesized to give a prescribed far-field intensity distribution and manufactured by milling the computed kinoform surface relief into a Teflon plate, using a numerically controlled milling machine. The measured diffraction efficiencies exceed 50 percent. Millimeter-wave kinoforms can be used in various quasi-optical applications,e.g. distributing a local oscillator signal to an array of detector elements in heterodyne receivers. 相似文献
2.
Stellan Hjertén 《Chromatographia》2007,65(9-10):509-509
3.
The purpose of this study was to develop an analysis system for studying the relationship between vocal fold vibration and the associated transglottal airflow. Recordings of airflow, electroglottography (EGG), oral air pressure, and acoustic signals were performed simultaneously with high-speed imaging at a rate of approximately 1900 frames/s. Inverse filtered airflow is compared with the simultaneous glottal area extracted from the high-speed image sequence. The accuracy of the synchronization between the camera images and the foot pedal synchronization pulse was examined, showing that potential synchronization errors increase with time distance to the synchronization pulse. Therefore, analysis was limited to material near the synchronization pulse. Results corroborate previous predictions that air flow lags behind area, but also they reveal that relationships between these two entities may be complex and apparently varying with phonation mode. 相似文献
4.
Intraoral pressure and subglottal pressure, derived from tracheal puncture, were recorded with the electroglottographic signal for one normal speaking male during phonation. The mean subglottal pressure for vowels was also estimated by interpolating the intraoral pressure from surrounding /p/ occlusions. The pressure measurements were highly correlated (r = 0.98) and there were small pressure value differences (on average <2%). The effects of varying speech rate and mode of phonation on the pressure measurements are discussed. A decrease in pressure from the mean subglottal pressure for the open phase and an increase for the closed phase was found during the glottal vibratory cycles. 相似文献
5.
The prevalence of voice problems among patients consulting the primary health care unit of a small Swedish town during 1984 was investigated. A study of the records of 11,606 patients indicated that 102 of them consulted their doctor mainly because of voice problems. The period prevalence of voice problems in the population of 20,049 people was 0.5%. A follow-up examination 1 year later indicated that 44% of these patients still had voice problems. Among the patients with a voice disorder diagnosis made by means of indirect laryngoscopy in 1984, 72% still had a voice disorder diagnosis at the follow-up. It is pointed out that the doctor who is seeing a patient with voice problems should make a thorough examination including indirect laryngoscopy. It is also important to discuss the patient's smoking habits and professional vocal strain to prevent recurrence. 相似文献
6.
Artificial and highly selective antibodies (in the form of gel granules) against proteins can easily be synthesized by a simple, cost-effective imprinting technique [Liao, J.-L. et al., Chromatographia 1996, 42, 259-262]. Using the same method for synthesis of gel antibodies against viruses in combination with analysis by free zone electrophoresis in a rotating narrow bore tube we have shown that artificial gel antibodies against Semliki Forest Virus (wild type) can sense the difference between this virus and a mutant, although they differ in their chemical composition only by three amino acids in one of the three proteins on the surface of the virus particle. The reason for this extremely high resolution is explained by the fact that we use three types of selectivity: (i) shape selectivity (created by the close fit between the antigen and its imprint in the gel), (ii) bond selectivity in the contact area between the antigen and its imprint in the gel antibody, and (iii) charge selectivity, originating from slightly different structures or/and conformations of the antigens. 相似文献
7.
The separation of acidic and basic model proteins was studied in capillary free zone electrophoresis in a polyacrylamide-coated, electroosmosis-free capillary at pH below their isoelectric points (pI) using various buffers at pH 2.7-4.8 with UV detection at 200 nm. The separation performance was significantly dependent on the coating quality, which may even differ within the same batch of capillaries. In addition, a washing step with 2 M HCl and the storage of the capillary in distilled water was essential for the performance. For high efficiency and resolution the choice of buffer constituents was extremely important which is discussed in quantitative terms in Part I. The most promising buffers were ammonium acetate and ammonium hydroxyacetate at pH 4 (ionic strengths: 0.12 and 0.15 M, respectively) with plate numbers up to 1,700,000 plates/m, corresponding to a zone width (2sigma) of only 1 mm in a capillary with 40 cm effective length, when the injected samples were dissolved in a 10-fold diluted background electrolyte (BGE), a zone even narrower than those obtained in polyacrylamide gel electrophoresis, the characteristic feature of which is remarkably thin zones. In the experiment giving this plate number, the calculated variance for longitudinal diffusion was larger than all the other calculated variances (those for the width of the starting zone, Joule heating, sedimentation and the curvature of the capillary). Interestingly, the effect of capillary curvature was significant. In addition, the sum of all other imaginable variances (corresponding to various types of slow on/off kinetics and hyper-sharp peaks) was in the most successful experiments only 28-50% of the variance for longitudinal diffusion. One hundred- to two hundred-fold dilution of the BGE improved the detection limits and provided high precision in both migration times and peak areas with ammonium hydroxyacetate and ammonium acetate as background electrolytes. However, that high dilution increased the variance 140-400% for these buffers, respectively, at least partly due to conductivity or pH differences between the sample and buffer zones (hyper-sharp peaks). Sedimentation of the enriched sample, a factor that has not previously been treated theoretically or experimentally, was probably another reason for our finding that peak heights did not increase when the sample was dissolved in a buffer diluted more than 200-fold, although pH changes and in some cases thermal expansion in the capillary also may contribute. Loss of protein may occur at the ionic strength 0.01 and lower due to precipitation. Limits of detection were in the range 4-17 pmol of proteins with ammonium acetate as BGE. No indication of denaturation of proteins at pH 4 was observed. However, the separation performance at pH 3 was not satisfactory and loss of proteins was observed, possibly indicating such problems. The protein mobilities decreased unexpectedly from pH 4 to 3--a further indication of conformation changes. 相似文献
8.
High selectivity of a biomarker is a basic requirement when it is used for diagnosis, prognosis and treatment of a disease. The artificial gel antibodies, which we synthesise by a molecular imprinting method, have this property not only for proteins, but also for bioparticles, such as viruses and bacteria. However, diagnosis of a disease requires not only that the biomarker can be “fished out” from a body fluid with high selectivity, but also that its concentration in the sample can rapidly be determined and preferably by a simple technique. This paper deals primarily with the development of a spectrophotometric method, which is so simple and fast that it can be used with advantage in a Doctor's Office. The development of this method was not straight‐forward. However, by modifications of the performance of these measurements we can now design standard curves in the form of a straight line, when we plot the true (not the recorded “apparent” absorption) against known protein concentrations. In an additional publication (see the following paper in this issue of JSS) we show an application of such a plot: determination of the concentration of albumin in serum and cerebrospinal fluid from patients with neurological disorders to investigate whether albumin is a biomarker for these diseases. 相似文献
9.
Stellan Ostlund David Rand James Sethna Eric Siggia 《Physica D: Nonlinear Phenomena》1983,8(3):303-342
An exact renormalization group transformation is developed for dissipative systems which describes how the transition to chaos may occur in a continuous and universal manner if the frequency ratio in the quasi-periodic regime is held at a fixed irrational value. Our approach is a natural extension of K.A.M. theory to strong coupling. Most of our analysis is for analytic circle maps. We have found a strong coupling fixed point where invertibility is lost, which describes the universal features of the transition to chaos. We find numerically that any two such critical maps with the same winding number are C1 conjugate. It follows that the low frequency peaks in an experimental spectrum are universal and we determine how their envelope scales with frequency.When the winding number has a periodic continued fraction, our renormalization transform has a fixed point and spectra are self similar in addition. For a set of non-periodic winding numbers with full measure our renormalization transformation yields an ergodic trajectory in a sub-space of all critical maps. Physically one finds singular and universal spectra that do not scale. 相似文献
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