Atmospheric aerosols play a major role in many atmospheric processes concerning the earth’s radiation budget, air quality, clouds and percipitation, and atmospheric chemistry. A multiwavelength Mie-Polarization-Raman lidar system is developing at Shandong Academy of Sciences Institute of Oceanorgraphic Instrumentation (SDIOI), which is used for the profiling of optical and physical aerosol properties. This system is specifically designed for characterizing marine aerosol which consists of a complex mix of different aerosol types. The aerosol lidar consists of a tripled Nd:YAG laser with three wavelengths, 30 cm telescope, six receiver channels and data acquistion subsystem. It provides particle backscatter coefficients at 355, 532 and 1064 nm (3β), extinction coefficients at 355 and 532 nm (2α), and depolarization ratio (σ). There are two Raman channels to collect the Raman signals backscattered by nitrogen molecules at 607 nm and by water vapor moecules at 407 nm. In this paper, we mainly describe the details of the optical setup, structure and performance of the lidar system. At last, the simulated signals based on the specifications are presented to demonstrate the capabilities of the lidar system.
Temporal lobe epilepsy (TLE) is one of the most common epilepsy syndromes with focal seizures generated in the left or
right temporal lobes. With the magnetic resonance imaging (MRI), many evidences have demonstrated that the
abnormalities in hippocampal volume and the distributed atrophies in cortical cortex. However, few studies have
investigated if TLE patients have the alternation in the structural networks. In the present study, we used the cortical
thickness to establish the morphological connectivity networks, and investigated the network properties using the graph
theoretical methods. We found that all the morphological networks exhibited the small-world efficiency in left TLE,
right TLE and normal groups. And the betweenness centrality analysis revealed that there were statistical inter-group
differences in the right uncus region. Since the right uncus located at the right temporal lobe, these preliminary evidences
may suggest that there are topological alternations of the cortical anatomical networks in TLE, especially for the right
TLE.
Hippocampal sclerosis (HS) is the most common damage seen in the patients with temporal lobe epilepsy (TLE). In the
present study, the hippocampal-cortical connectivity was defined as the correlation between the hippocampal volume and
cortical thickness at each vertex throughout the whole brain. We aimed to investigate the differences of ipsilateral
hippocampal-cortical connectivity between the unilateral TLE-HS patients and the normal controls. In our study, the
bilateral hippocampal volumes were first measured in each subject, and we found that the ipsilateral hippocampal
volume significantly decreased in the left TLE-HS patients. Then, group analysis showed significant thinner average
cortical thickness of the whole brain in the left TLE-HS patients compared with the normal controls. We found
significantly increased ipsilateral hippocampal-cortical connectivity in the bilateral superior temporal gyrus, the right
cingulate gyrus and the left parahippocampal gyrus of the left TLE-HS patients, which indicated structural vulnerability
related to the hippocampus atrophy in the patient group. However, for the right TLE-HS patients, no significant
differences were found between the patients and the normal controls, regardless of the ipsilateral hippocampal volume,
the average cortical thickness or the patterns of hippocampal-cortical connectivity, which might be related to less
atrophies observed in the MRI scans. Our study provided more evidence for the structural abnormalities in the unilateral
TLE-HS patients.
Resting-state functional magnetic resonance imaging (fMRI) is a technique that measures the intrinsic function of brain
and has some advantages over task-induced fMRI. Regional homogeneity (ReHo) assesses the similarity of the time
series of a given voxel with its nearest neighbors on a voxel-by-voxel basis, which reflects the temporal homogeneity of
the regional BOLD signal. In the present study, we used the resting state fMRI data to investigate the ReHo changes of
the whole brain in the prelingually deafened patients relative to normal controls. 18 deaf patients and 22 healthy subjects
were scanned. Kendall's coefficient of concordance (KCC) was calculated to measure the degree of regional coherence
of fMRI time courses. We found that regional coherence significantly decreased in the left frontal lobe, bilateral
temporal lobes and right thalamus, and increased in the postcentral gyrus, cingulate gyrus, left temporal lobe, left
thalamus and cerebellum in deaf patients compared with controls. These results show that the prelingually deafened
patients have higher degree of regional coherence in the paleocortex, and lower degree in neocortex. Since neocortex
plays an important role in the development of auditory, these evidences may suggest that the deaf persons reorganize the
paleocortex to offset the loss of auditory.
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