We propose a directive antenna for borehole radar using a horizontally polarized wave in a vertical borehole. This antenna is an array of several horizontal loop antennas, arranged vertically. When a ...plane wave is incident on the antenna, the differences in arrival times at the array elements enable us to estimate the direction of arrival (DOA). We present a simple model representing the arrival time difference and propose an algorithm for DOA estimation. Furthermore, we synthesized the array signal by analyzing the electromagnetic field using the method of moments (MoM) and applied the proposed algorithm to the signal. We found that mutual coupling between antenna elements affects the DOA estimation and that a space of about 3 cm between antenna elements prevents mutual coupling. Using the MoM analysis, we simulated a cross-hole measurement to demonstrate the antenna's ability. We carried out field experiments in wet soil to examine the antenna's ability. The proposed loop array antenna in a water-filled borehole received a direct wave from a source in another borehole. After applying the proposed algorithm to the measured data, we found that we could estimate the DOAs to the source with an error of less than 15° in the azimuth angle and 10° in the elevation angle.
Purpose
To determine whether there are significant correlations between the focal photopic negative response (PhNR), the focal visual sensitivity and the ganglion cell complex (GCC) thickness in ...glaucomatous eyes.
Study design
Single-center observational study.
Methods
Fifty-two eyes of 52 patients (71.4 ± 9.42 years) with clinically diagnosed open angle glaucoma were studied. Thirty-six age-matched normal subjects served as controls. The focal PhNR of the focal macular electroretinograms (fmERGs) were elicited by a 15° circular, a superior semicircular or an inferior semicircular stimulus centered on the fovea. The thickness of the GCC was measured in the corresponding retinal areas in the spectral-domain optical coherence tomographic images. The visual sensitivities (dB) were measured by microperimetry at the retinal area where the fmERGs were elicited and were converted to liner values (1/Lambert).
Results
The focal PhNR amplitudes were significantly correlated with the visual sensitivities of the full-circle (
R
= 0.532), the superior (
R
= 0.530) and inferior (
R
= 0.526) semicircular responses (
P
< 0.0001). The GCC thickness was correlated with the visual sensitivities in the same areas with stronger correlations (
R
= 0.700, 0.759 and 0.650, respectively;
P
< 0.0001). The focal PhNR amplitudes were proportionally reduced with the thinning of the GCC thickness (
R
= 0.494, 0.518 and 0.511, respectively;
P
< 0.0001).
Conclusions
The significant correlations between the focal PhNR amplitudes, the focal visual sensitivities and the GCC thickness indicate that these may be good biomarkers to track the changes in the physiology and anatomy of the macular area in glaucomatous eyes.
Purpose
To compare the clinical significance of the photopic negative response (PhNRs) elicited by different stimuli from glaucomatous eyes.
Study design
Single-center observational study
Method
...Eighty-four eyes of 84 patients with open angle glaucoma (OAG) and 40 eyes of 40 normal subjects were studied. Cone electroretinograms (ERGs) were elicited by white stimuli on a white background (W/W) or red stimuli on a blue background (R/B). The luminance of the stimuli was 0.5, 1.0, 2.0 or 3.0 cd-s/m
2
, and of the background light was 10 cd/m
2
. The first and second troughs of the ERGs that appeared following the b-wave were designated as PhNR1 and PhNR2, respectively. The thickness of the circumpapillary retinal nerve fiber layer (cpRNFL) was measured by spectral-domain optical coherence tomography. The mean deviation (MD) was determined by standard automated perimetry. The area under the receiver operating characteristic curves (AUCs) was created to determine the diagnostic ability of the PhNRs elicited by the different stimulus conditions.
Results
The correlation coefficients of the amplitudes of the PhNR1 elicited by W/W stimuli to the MDs and cpRNFL thickness were generally stronger, and the regression lines steeper than for the amplitudes of the PhNR1 elicited by R/B stimuli. In contrast, the correlation coefficients of the amplitudes of the PhNR2 elicited by R/B stimuli to the MDs and cpRNFL thickness were generally stronger, and the regression lines were steeper than the amplitudes of the PhNR2 elicited by W/W stimuli. With both types of stimuli, the slopes of the regression lines became steeper when the ERG recorded with higher stimulus intensities. The AUCs were significantly larger for the PhNR2 elicited by the R/B stimuli at 3.0 cd-s/m
2
than for PhNR1 and PhNR2 elicited by W/W stimuli at the same intensity when the PhNRs were used for diagnosing advanced glaucoma.
Conclusion
The PhNR1 and PhNR2 elicited by the W/W and R/B stimuli are suitable measures to assess the function of the RGCs in eyes with OAG. The PhNR2 elicited by R/B stimuli at higher stimulus intensities is most effective in detecting functional and structural changes of the RGCs with the highest diagnostic capacity in discriminating advanced glaucoma.
Purpose
To determine the significance of the correlation between the vascular structure and neural function of the macula in patients with diabetes mellitus.
Study design
Single-center observational ...study.
Patients and methods
Ninety eyes of 90 diabetic patients with an average (SD) age of 63.5 (3.8) years were studied. Fifty of the eyes had no clinically apparent diabetic retinopathy (non-DR), and 40 eyes had mild-to-moderate nonproliferative DR (NPDR). Thirty age-matched healthy individuals were also studied in the same way. Swept-source optical coherence tomography angiography (OCTA) was performed to obtain 3 × 3-mm en face images of the posterior pole of the eye. The vascular densities (VDs) of the superficial capillary plexus (SCP) and the deep capillary plexus (DCP) were determined. The focal macular electroretinograms (ERGs) elicited by a 15° circular stimulus centered on the fovea were recorded. The amplitudes of the a- and b-waves, sum of the oscillatory potentials (ΣOPs), photopic negative response (PhNR), and implicit times of the individual OPs (OP1-OP3) were measured.
Results
The VDs of the SCP and DCP were reduced in eyes with advanced DR (
P
< .01 for SCP). The implicit times of OP1-OP3 were significantly prolonged in eyes with a lower VD of the SCP and DCP in the non-DR group (
P
< .05). The amplitudes of the ΣOPs were significantly smaller in eyes with a reduced VD of the SCP and DCP in the NPDR group (
P
< .05). The correlation coefficients were higher for the OP implicit times than for the ΣOP amplitudes in the non-DR group.
Conclusions
The OPs of the focal macular ERG are smaller with prolonged implicit times in association with capillary loss in the macula of diabetic patients. The implicit times are the most sensitive functional parameter that reflects the early changes of the microvasculature in the macula caused by diabetes.
There is no report on antibody titers after vaccination against SARS-CoV-2 in Japanese dialysis patients. As dialysis is different between Japan and other countries, changes in antibody titers were ...examined.
Baseline characteristics and anti-spike protein antibody titers (Roche) over 90 days after administration of the BNT162b2 messenger RNA vaccine were investigated in dialysis patients.
The maximum anti-spike protein antibody titer after the second dose was 738 (327 to 1143) U/mL and was reached at 19 (17 to 24) days after the second dose. Antibody titers decreased over time, with titers of 770 (316 to 1089) U/mL at 15 days, 385 (203 to 690) U/mL at 30 days, 254 (138 to 423) U/mL at 60 days, and 208 (107 to 375) U/mL at 90 days after the second dose. When an antibody titer of 137 U/mL was assumed to be a measure related to breakthrough infection, the proportion of subjects with antibody titers exceeding this level was 90.1% at 15 days, 85.3% at 30 days, 75.0% at 60 days, and 65.4% at 90 days after the second dose. When a decrease in antibody titers below the assumed breakthrough level was defined as an event, subjects with a pre-dialysis albumin ≥ 3.5 g/dL were significantly less likely to experience an event than subjects with a pre-dialysis albumin < 3.5 g/dL.
The presence of anti-spike protein levels ≥ 313 U/mL at 30 days after the second vaccine dose might be a factor in maintaining enough antibody titers at 90 days after. Whether an additional vaccine dose is needed should be determined based on indicators serving as factors in maintaining antibody titers as well as the status of the spread of infection.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We propose a polarization-sensitive directional borehole radar with a dipole array and loop antenna in a borehole (DALAB), along with an algorithm for radar signal processing. This radar enables us ...to discriminate between a vertical conducting cylinder and inhomogeneity in soil in 3-D space. The antenna configuration difference, antenna coupling, and borehole effects were calibrated using the method of moments (MoM) in the proposed algorithm. According to computer simulation, the magnitude of the polarization ratio (MPR) of the incident wave may be used for discrimination between signals from targets and background reflections. A prototype of the borehole radar with the DALAB was constructed and tested in laboratory and field experiments. In the laboratory, we confirmed that the DALAB can estimate the polarization state of an incident wave despite the presence of a water layer. In field testing, we confirmed that the MPR was nearly 0 dB, as theoretically estimated when the DALAB received electromagnetic waves radiated by a tilted dipole antenna. We also carried out single-hole measurements with the DALAB and found that the MPR of a reflected wave from a vertical conducting cylinder was more than 20 dB, whereas that from soil inhomogeneity was less than about 20 dB. This implies that we may discriminate between a conducting cylinder and soil inhomogeneity and determine target locations in three dimensions using the DALAB and the MPR.
We consider the effects of oblique incidence of a wave on the creation of a 3-D image of a planar interface with an array-type directional borehole radar. In this study, we focus on the situation ...where the radar probe is close to the planar interface. In such circumstances, the reflected wave from the planar interface may be incident on the receiving array antenna at very steep elevation angles. As a result, borehole effects cause differences in the arrival times of the wave at the array elements, and consequently some errors emerge in imaging the planar interface. Observing the arrival time differences, we present an algorithm to compensate those errors in creating a 3-D image of a planar interface. Computer simulations predict that the errors may occur when the circular dipole array antenna is in an air-filled borehole in rock. Numerical simulations show that our proposed algorithm generates a 3-D image of an interface around an exact position, whereas conventional methods produce some spurious images opposite to the correct position (i.e., out of position by 180°). We then applied the proposed method to analyze reflected waves from a real-world fault in rock. A 3-D image of the fault could be successfully created, which was not possible using the conventional method.
Purpose. To determine the long-term changes of the thickness of each retinal layer following macular hole (MH) surgery combined with internal limiting membrane (ILM) peeling. Method. The medical ...records of 42 eyes of 42 patients (41 to 86 years of age) who underwent MH surgery with ILM peeling between February 2016 and October 2018 were reviewed. A single surgeon operated on all patients, and all were followed for at least 24 months postoperatively. Spectral-domain optical coherence tomography (OCT) was performed to obtain retinal thickness maps of the parafoveal region corresponding approximately to the ILM peeled area. Each retinal layer was automatically segmented by the embedded software, and thickness maps were constructed for the total retinal layer (TRL), inner RL (IRL), middle RL (MRL), and outer RL (ORL). The averaged value of each retinal layer thickness was analyzed in the temporal/upper, temporal/lower, nasal/upper, and nasal lower quadrants. Results. The TRL thickness was significantly decreased in the temporal areas postoperatively. The IRL thickness thinned progressively and significantly until 6 months without further thinning in the temporal quadrants. The MRL thickness of all areas was significantly thicker than the baseline values at 0.5 months and then gradually decreased in the temporal regions. However, the thickening in the nasal regions returned to the baseline values after 1.5 months. The ORL decreased transiently relative to the baseline values at 0.5 months in all areas. Conclusions. The ILM peeling does not affect only the thickness of the inner retina but also the middle and outer retinae in the parafoveal region. The chronological changes of the thickness after surgeries varied among the retinal layers and macular regions.
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