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We report on earthquake and temperature-related velocity changes in high-frequency autocorrelations of ambient noise data from seismic stations of the Integrated Plate Boundary Observatory Chile project in northern Chile. Daily autocorrelation functions are analyzed over a period of 5 years with passive image interferometry. A short-term velocity drop recovering after several days to weeks is observed for the Mw 7.7 Tocopilla earthquake at most stations. At the two stations PB05 and PATCX, we observe a long-term velocity decrease recovering over the course of around 2 years. While station PB05 is located in the rupture area of the Tocopilla earthquake, this is not the case for station PATCX. Station PATCX is situated in an area influenced by salt sediment in the vicinity of Salar Grande and presents a superior sensitivity to ground acceleration and periodic surface-induced changes. Due to this high sensitivity, we observe a velocity response of several regional earthquakes at PATCX, and we can show for the first time a linear relationship between the amplitude of velocity drops and peak ground acceleration for data from a single station. This relationship does not hold true when comparing different stations due to the different sensitivity of the station environments. Furthermore, we observe periodic annual velocity changes at PATCX. Analyzing data at a temporal resolution below 1 day, we are able to identify changes with a period of 24 h, too. The characteristics of the seismic velocity with annual and daily periods indicate an atmospheric origin of the velocity changes that we confirm with a model based on thermally induced stress. This comprehensive model explains the lag time dependence of the temperature-related seismic velocity changes involving the distribution of temperature fluctuations, the relationship between temperature, stress and velocity change, plus autocorrelation sensitivity kernels.

Infrared (IR) optical fiber have aroused great interest in recent years because of their potential in in-vivo spectroscopy. This potential includes the ability to be flexible, small and to guide IR light in a very large range of wavelengths. Two types - silver halide and chalcogenide - infrared transmitting fibers are investigated in the detection of a malignant tumor. As a test sample for all types of fibers we used a thin section of an entire rat brain with glioblastoma. The fibers were connected with a common infrared microscope. Maps across the whole tissue section with more than 200 spectra were recorded by moving the sample with an XY stage. Data evaluation was performed using fuzzy c-means cluster analysis (FCM). The silver halide fibers provided excellent results. The tumor was clearly discernible from healthy tissue. Chalcogenide fibers are not suitable to distinguish tumor from normal tissue because the fiber has a very low transmittance in the important fingerprint region.

The use of several silver halide and chalcogenide infrared transmitting fibers in the detection of cancer is investigated. As a test sample for all types of fibers we used a thin section of an entire rat brain with glioblastoma. Moving the sample with an XY stage maps across the whole tissue section with more than 200 spectra were recorded. Data evaluation was performed using Principal Components Analysis (PCA). The silver halide fibers have provided excellent results. The tumor was clearly differentiable from the normal tissue. It wasn't possible to identify the tumor region using chalcogenide fibers because the fiber has a very low transmittance in the important fingerprint region.

A method is described for identifying tumor tissue by means of FTIR microspectroscopy and positron emission tomography (PET). Thin tissue sections of human squamous carcinoma from hypopharynx (FaDu) and human colon adenocarcinoma (HT-29) grown in nude mice were investigated. FTIR spectroscopic maps of the thin tissue sections were generated and evaluated by Fuzzy C-Means (FCM) clustering and principal component analysis (PCA). The processed data were reassembled into images and compared to stained tissue samples and to PET. Tumor tissue could successfully be identified by this FTIR microspectroscopic method, while it was not possible to accomplish this with PET alone. On the other hand, PET permitted the non-invasive screening for suspicious tissue inside the body, which could not be achieved by FTIR.

A combination of FTIR spectroscopy and positron emission tomography (PET) is shown to provide new information on tissue. Here we give a first demonstration on the potential of this combination in discriminating tumor tissue from healthy tissue. Examples are taken of cancer grown in muscle tissue in mice. Immediately before thin sections of the cancer tissue were prepared, a radiotracer was injected in the living mouse. Subsequently a native section was immobilized on a CaF2 window and an autoradiographic image was recorded from that immobilized section. FTIR maps of the thin sections were obtained by using an infrared microscopy equipped with computerized XY stage and MCT detector. Principal component analysis was chosen for chemometric evaluation of the spectra. Evaluated data were reassembled into 2D maps and compared with the corresponding PET image.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The design and the main features of the new double pendulum type michelson interferometer (DPI) by Kayser-Threde are presented. The advantages of this spectrometer in comparison to conventional Fourier spectrometers are discussed. The DPI is compact in design, mobile, insensitive to vibrations and temperature changes and, thus, well adapted to field measurements. The spectrometer was applied to emission as well as immission measurements of air pollutants. Several molecules could be identified and their concentrations could be estimated. The detection limit of the DPI yields 15 - 60 ppm depending on the analyzed gas for emission measurements, 6 - 84 ppb for immission measurements.