RESUMO
The Lucy Thermal Emission Spectrometer (L'TES) will provide remote measurements of the thermophysical properties of the Trojan asteroids studied by the Lucy mission. L'TES is build-to-print hardware copy of the OTES instrument flown on OSIRIS-REx. It is a Fourier Transform spectrometer covering the spectral range 5.71-100 µm (1750-100 cm-1) with spectral sampling intervals of 8.64, 17.3, and 34.6 cm-1 and a 7.3-mrad field of view. The L'TES telescope is a 15.2-cm diameter Cassegrain telescope that feeds a flat-plate Michelson moving mirror mounted on a linear voice-coil motor assembly to a single uncooled deuterated l-alanine doped triglycine sulfate (DLATGS) pyroelectric detector. A significant firmware change from OTES is the ability to acquire interferograms of different length and spectral resolution with acquisition times of 0.5, 1, and 2 seconds. A single â¼0.851 µm laser diode is used in a metrology interferometer to provide precise moving mirror control and IR sampling at 772 Hz. The beamsplitter is a 38-mm diameter, 1-mm thick chemical vapor deposited diamond with an antireflection microstructure to minimize surface reflection. An internal calibration cone blackbody target, together with observations of space, provides radiometric calibration. The radiometric precision in a single spectrum is ≤2.2 × 10-8 W cm-2 sr-1 /cm-1 between 300 and 1350 cm-1. The absolute temperature error is <2 K for scene temperatures >75 K. The overall L'TES envelope size is 37.6 × 29.0 × 30.4 cm, and the mass is 6.47 kg. The power consumption is 12.6 W average. L'TES was developed by Arizona State University with AZ Space Technologies developing the electronics. L'TES was integrated, tested, and radiometrically calibrated on the Arizona State University campus in Tempe, AZ. Initial data from space have verified the instrument's radiometric and spatial performance.
RESUMO
OBJECTIVE: There is limited information regarding changes in bone architecture following anterior cruciate ligament (ACL) injury. The objective of this study was to evaluate differences in tibial fractal signature in the medial and lateral compartments following ACL injury and describe how these values change following ACL-reconstruction and return to activity. DESIGN: This was a prospective cohort study with a nested case-control analysis. ACL-injured subjects and matched controls were evaluated at pre-surgical baseline and post ACL reconstruction follow-up at a mean of 46 months. Serial Fractal Dimensions (FD) of tibial subchondral bone architecture were calculated in medial and lateral regions of interest in the horizontal and vertical dimensions. RESULTS: In the medial and lateral compartments, there were significant differences in the vertical FD signature for ACL-injured subjects at final follow-up, when compared to the contralateral healthy tibia (medial P < 0.0001; lateral P < 0.0001) and the control group (medial P = 0.01; lateral P < 0.0001). Similarly, in the lateral compartment, there were significant differences in the horizontal FD profile for ACL-injured subjects at final follow-up, when compared to the contralateral healthy tibia (P = 0.003) and the controls (P < 0.0001). There were no significant side-to-side differences in FDs among healthy control subjects in the medial or lateral compartments at baseline or final follow-up. CONCLUSION: At 46-month follow-up, FD profiles are significantly different, and show an overall lower FD signature, for ACL-injured knees when compared to the contralateral healthy knee and uninjured controls. Additionally, this study provided the first side-to-side symmetry data of medial and lateral FD values in healthy controls.
