Search Results (6)

The Terrain Wide-swath Interferometric L-band Synthetic Aperture Radar (TwinSAR-L) mission is a spaceborne bistatic synthetic aperture radar (SAR) mission to derive a high-quality global digital elevation model (DEM). The prerequisite of the high-accuracy DEM is knowing the interferometric baseline with high precision. The challenging problem is that the baseline of the bistatic system is highly dynamic due to the fast relative motion between the two satellites. In this paper, a pixel-related baseline model based on the geometrical shift is proposed to accurately reflect the position change of satellites. The baseline error is then calibrated using height gradient information and a small number of point targets with a slight incidence angle difference, eliminating the need for low-frequency corner reflectors and avoiding the difficulty of selecting a calibration site. The proposed method has been successfully exploited during the initial Commissioning Phase of TwinSAR-L, demonstrating its effectiveness in evaluating the precise baseline and supporting the generation of high-precision DEM. Full article

Pregnant women who receive the COVID-19 vaccine develop anti-SARS-CoV-2 antibodies, which can be transferred to the fetus. However, the effectiveness of placental transfer has not been evaluated in twin pregnancy, especially in cases vaccinated with heterologous CoronaVac (Sinovac)—ChAdOx1 (Oxford-AstraZeneca) regimen, which was commonly used in many countries. Case: A 34-year-old Thai woman with a twin pregnancy attended our antenatal care clinic at 21 + 2 weeks of gestation and requested COVID-19 vaccination. Her medical history and physical examination were unremarkable. She had not received COVID-19 vaccination before. Ultrasound screening for fetal anomaly revealed a dichorion diamnion twin pregnancy. Both twins showed no structural anomaly. She received the CoronaVac vaccine at 21 + 2 weeks of gestation without serious side effects and the ChAdOx1 vaccine at 24 + 2 weeks of gestation. Cesarean delivery was performed at 36 + 5 weeks of gestation, giving birth to the two healthy babies. The levels of anti-spike protein IgG levels (BAU/mL) in maternal blood just before delivery and umbilical cord blood of the two newborns were 313.349, 678.219, and 874.853, respectively. The levels of % inhibition (wild-type and delta) in the two newborns were also higher than those in the mother. In conclusion, heterologous CoronaVac-ChAdOx1-S vaccination in a twin pregnancy could effectively provide protective immunity to both twin newborns. The antibody levels in both were approximately two times higher than those in the mothers. This case report may serve as a reference in counseling couples with a twin pregnancy, while the studies on placental transfer of vaccine-derived antibodies in twin pregnancy are currently not available, especially in countries experiencing a vaccine shortage or unavailability of mRNA vaccines. Full article

Cases of multisystem inflammatory syndrome in children (MIS-C-like disease), have rarely been reported in neonates. A 33-week gestational age twin B female neonate presented with respiratory distress, tachycardia, and abdominal distention at 15 days of age. Echocardiogram found reduced left ventricular ejection fraction to 33%. Cardiac enzyme levels were all elevated: creatine kinase-MB 6.1 ng/mL (normal 0–4.5 ng/mL), troponin-T 170 ng/L (normal < 14 ng/L) and NT-proBNP > 35,000 pg/mL (normal 250.0 to 3987.0 pg/mL). Multiplex PCR of nasopharyngeal swab material was negative for respiratory pathogens. Serological tests revealed negative anti-spike SARS-CoV-2 IgM but positive anti-nucleocapsid SARS-CoV-2 IgG in both the mother and the patient. The mother provided a history of COVID-19 during pregnancy at 19 weeks gestation. The patient was diagnosed with neonatal multisystem inflammatory syndrome (MIS-N) and successfully treated with intravenous immunoglobulin (two doses of 1 gm/kg/dose) and methylprednisolone (2 mg/kg/day for 5 days then tapered off). She later developed coronary vessel (LMCA and RCA) dilation. The non-identical twin A did not develop MIS-N, suggesting a role of host genetic background. Newborn infants born to SARS-CoV-2-infected mothers at any time during pregnancy should be closely monitored for MIS-N. The optimal treatment approaches to this syndrome and the prognosis require further study. Full article

Almond, one of the most characteristic crops in the agricultural landscape of Mallorca Island, cultivated mainly under rainfed conditions and from native cultivars, represents an important source of income for the Island. Nowadays, modern cultivars were introduced to meet the almond demand, agronomical needs, and climate change issues. Consumption has considerably increased in the last years and the SARS-CoV-2 virus contributed to consumer behavior changes. The present work aimed to characterize 14 cultivars of which 9 were modern and 5 natives. In general, the natives cultivars presented a lower weight (1.3 g), size (21 mm), darker skin (L = 38), softer texture (107 N), with more benzaldehyde flavor (2-fold change) and “twins” (16%), but with a greater thickness, fiber, and linoleic acid (0.1-fold change, respectively). Modern cultivars offered greater weight (1.5 g), size (24 mm), lighter skin (L = 39), and harder texture (121 N), with no or low benzaldehyde flavor and no “twins”. Finally, ‘Belona’, ‘Ferragnès’, ‘Marta’, ‘Masbovera’, ‘Penta’, ‘Soleta’, ‘Vairo’, ‘Duareta’, ‘Jordi’ and ‘Vivot’ met all the requirements to be certified under the quality guarantee Protected Indication of Origin “Almendra de Mallorca”. However, each cultivar presented its own profile which makes them suitable for different purposes in the food industry. Full article

In this paper, additional reference height errors, caused by the penetration depth and Signal to Noise Ratio (SNR) decorrelation in desert regions in L-band spaceborne bistatic interferemetric SAR, will introduce significant errors in nowadays baseline calibration method based on distributed target and consequent DEM products. To quantify these two errrors, this paper takes the TwinSAR-L mission as an example, gives an introduction of TwinSAR-L, outlines the theoretical baseline accuracy requirements that need to be satisfied in the TwinSAR-L mission and addresses the additional reference height errors caused by the penetration depth and SNR decorrelation in desert regions in general by taking the TwinSAR-L mission as an example. Based on ALOS-2 data from a dry desert region in the east of Xing Jiang, this paper quantitatively analyzes these additional reference height errors. The results show that the additional reference height errors resulted from the penetration depth and the SNR decorrelation are 1.295 m and 1.39 m, respectively, which would even cause 6.4 mm and 8.6 mm baseline calibration errors. These errors would seriously degrade the baseline calibration accuracy and the consequent DEM product quality. Therefore, our analysis is of great significance not only for baseline calibration, but also for high-quality DEM’s generation, accuracy assessment and geophysical parameters’ quantitative inversion and application. Full article

Persistent Scatterer Interferometry (PS-InSAR) has become an indispensable tool for monitoring surface motion in urban environments. The interferometric configuration of PS-InSAR tends to mix topographic and deformation components in differential interferometric observations. When the upcoming constellation missions such as, e.g., TanDEM-L or TWIN-L provide new standard operating modes, bi-static stacks for deformation monitoring will be more commonly available in the near future. In this paper, we present an analysis of the applicability of such data sets for urban monitoring, using a stack of pursuit monostatic data obtained during the scientific testing phase of the TanDEM-X (TDX) mission. These stacks are characterized by extremely short temporal baselines between the TerraSAR-X (TSX) and TanDEM-X acquisitions at the same interval. We evaluate the advantages of this acquisition mode for urban deformation monitoring with several of the available acquisition pairs. Our proposed method exploits the special properties of this data using a modified processing chain based on the standard PS-InSAR deformation monitoring procedure. We test our approach with a TSX/TDX mono-static pursuit stack over Guangzhou, using both the proposed method and the standard deformation monitoring procedure, and compare the two results. The performance of topographic and deformation estimation is improved by using the proposed processing method, especially regarding high-rise buildings, given the quantitative statistic on temporal coherence, detectable numbers, as well as the PS point density of persistent scatters points, among which the persistent scatter numbers increased by 107.2% and the detectable height span increased by 78% over the standard processing results. Full article