Remote sensing of seasonal changes and disturbances in mangrove forest: a case study from South Florida

Knowledge of the spatial and temporal changes caused by episodic disturbances and seasonal variability is essential for understanding the dynamics of mangrove forests at the landscape scale, and for building a baseline that allows detection of the effects of future environmental change. In combination with LiDAR data, we calculated four vegetation indices from 150 Landsat TM images from 1985 to 2011 in order to detect seasonal changes and distinguish them from disturbances due to hurricanes and chilling events in a mangrove-dominated coastal landscape. We found that normalized difference moisture index (NDMI) performed best in identifying both seasonal and event-driven episodic changes. Mangrove responses to chilling and hurricane events exhibited distinct spatial patterns. Severe damage from intense chilling events was concentrated in the interior dwarf and transition mangrove forests with tree heights less than 4 m, while severe damage from intense hurricanes was limited to the mangrove forest near the coast, where tree heights were more than 4 m. It took 4–7 months for damage from intense chilling events and hurricanes to reach their full extent, and took 2–6 yr for the mangrove forest to recover from these disturbances. There was no significant trend in the vegetation changes represented by NDMI over the 27-yr period, but seasonal signals from both dwarf and fringe mangrove forests were discernible. Only severe damage from hurricanes and intense chilling events could be detected in Landsat images, while damage from weak chilling events could not be separated from the background seasonal change

REVIEWS REVIEWS REVIEWS Disturbance and the rising tide: the

low-island ecosystem

Airborne Laser Scanning Quantification of Disturbances from Hurricanes and Lightning Strikes to Mangrove Forests in Everglades National Park, USA

Airborne light detection and ranging (LIDAR) measurements derived before and after Hurricanes Katrina and Wilma (2005) were used to quantify the impact of hurricanes and lightning strikes on the mangrove forest at two sites in Everglades National Park (ENP). Analysis of LIDAR measurements covering 61 and 68 ha areas of mangrove forest at the Shark River and Broad River sites showed that the proportion of high tree canopy detected by the LIDAR after the 2005 hurricane season decreased significantly due to defoliation and breakage of branches and trunks, while the proportion of low canopy and the ground increased drastically. Tall mangrove forests distant from tidal creeks suffered more damage than lower mangrove forests adjacent to the tidal creeks. The hurricanes created numerous canopy gaps, and the number of gaps per square kilometer increased from about 400~500 to 4000 after Katrina and Wilma. The total area of gaps in the forest increased from about 1~2% of the total forest area to 12%. The relative contribution of hurricanes to mangrove forest disturbance in ENP is at least 2 times more than that from lightning strikes. However, hurricanes and lightning strikes disturb the mangrove forest in a related way. Most seedlings in lightning gaps survived the hurricane impact due to the protection of trees surrounding the gaps, and therefore provide an important resource for forest recovery after the hurricane. This research demonstrated that LIDAR is an effective remote sensing tool to quantify the effects of disturbances such as hurricanes and lightning strikes in the mangrove forest

Mapping Height and Biomass of Mangrove Forests in Everglades National Park with SRTM Elevation Data

We produced a landscape scale map of mean tree height in mangrove forests in Everglades National Park (ENP) using the elevation data from the Shuttle Radar Topography Mission (SRTM). The SRTM data was calibrated using airborne lidar data and a high resolution USGS digital elevation model (DEM). The resulting mangrove height map has a mean tree height error of 2.0 m (RMSE) over a pixel of 30 m. In addition, we used field data to derive a relationship between mean forest stand height and biomass in order to map the spatial distribution of standing biomass of mangroves for the entire National Park. The estimation showed that most of the mangrove standing biomass in the ENP resides in intermediate- height mangrove stands around 8 m. We estimated the total mangrove standing biomass in ENP to be 5.6 X 109 kg

5 x 20 Gb/s III-V on silicon electroabsorption modulator array heterogeneously integrated with a 1.6nm channel-spacing silicon AWG

We demonstrate a five-channel wavelength division multiplexed modulator module that heterogeneously integrates a 1.6nm channel-spacing arrayed-waveguide grating and a 20Gbps electroabsorption modulator array, showing the potential for 100 Gbps capacity on a 1.5x0.5 mm(2) footprint

A Systematic Approach for Inertial Sensor Calibration of Gravity Recovery Satellites and Its Application to Taiji-1 Mission

High-precision inertial sensors or accelerometers can provide us references of free-falling motions in gravitational field in space. They serve as the key payloads for gravity recovery missions such as the CHAMP, the GRACE-type missions, and the planned Next Generation Gravity Missions. In this work, a systematic method of electrostatic inertial sensor calibrations for gravity recovery satellites is suggested, which is applied to and verified with the Taiji-1 mission. With this method, the complete operating parameters including the scale factors, the center of mass offset vector and the intrinsic biased acceleration can be precisely calibrated with only two sets of short-term in-orbit experiments. Taiji-1 is the first technology demonstration satellite of the "Taiji Program in Space", which, in its final extended phase in 2022, could be viewed as operating in the mode of a high-low satellite-to-satellite tracking gravity mission. Based on the calibration principles, swing maneuvers with time span about 200 s and rolling maneuvers for 19 days were conducted by Taiji-1 in 2022. The inertial sensor's operating parameters are precisely re-calibrated with Kalman filters and are updated to the Taiji-1 science team. Data from one of the sensitive axis is re-processed with the updated operating parameters, and the performance is found to be slightly improved compared with former results. This approach could be of high reference value for the accelerometer or inertial sensor calibrations of the GFO, the Chinese GRACE-type mission, and the Next Generation Gravity Missions. This could also shed some light on the in-orbit calibrations of the ultra-precision inertial sensors for future GW space antennas because of the technological inheritance between these two generations of inertial sensors.Comment: 24 pages, 19 figure

Targeting cellular senescence in senile osteoporosis: therapeutic potential of traditional Chinese medicine

Senile osteoporosis (SOP) is a prevalent manifestation of age-related bone disorders, resulting from the dysregulation between osteoblast (OB)-mediated bone formation and osteoclast (OC)-mediated bone resorption, coupled with the escalating burden of cellular senescence. Traditional Chinese medicine (TCM) herbs, renowned for their remarkable attributes encompassing excellent tolerability, low toxicity, heightened efficacy, and minimal adverse reactions, have gained considerable traction in OP treatment. Emerging evidence substantiates the therapeutic benefits of various TCM formulations and their active constituents, including Zuogui wan, Fructus Ligustri Lucidi, and Resveratrol, in targeting cellular senescence to address SOP. However, a comprehensive review focusing on the therapeutic efficacy of TCM against SOP, with a particular emphasis on senescence, is currently lacking. In this review, we illuminate the pivotal involvement of cellular senescence in SOP and present a comprehensive exploration of TCM formulations and their active ingredients derived from TCM, delineating their potential in SOP treatment through their anti-senescence properties. Notably, we highlight their profound effects on distinct aging models that simulate SOP and various senescence characteristics. Finally, we provide a forward-looking discussion on utilizing TCM as a strategy for targeting cellular senescence and advancing SOP treatment. Our objective is to contribute to the unveiling of safer and more efficacious therapeutic agents for managing SOP

Ammonia Affects Mitochondrial Cell Apoptosis and Tenderness in Postmortem Yak Meat by Regulating Hypoxia Inducible Factor-1α Expression

This study aimed to investigate the effect of ammonia mediated hypoxia inducible factor-1α (HIF-1α) expression on mitochondrial cell apoptosis and tenderness in yak meat after slaughter. Ten mmol/L ammonium chloride (NH4Cl), 0.9% normal saline (control) and 10 mmol/L N-nitro-L-arginine methyl ester hydrochloride were used separately for treating yak Longissimus dorsi. By measuring the expression of HIF-1α, nitrogen monoxide (NO) content, energy metabolism-related enzyme activities, adenosine triphosphate (ATP) level, mitochondrial pathway of apoptosis and muscle tenderness, we explored the mechanism of cell apoptosis and tenderness change in yak meat after slaughter. The results showed that during the postmortem aging of yak meat, the expression of HIF-1α and the content of NO in each treatment group increased first and then decreased, and so did the activities of Na+-K+-ATPase, Ca2+-ATPase, caspase-9 and caspase-3 and shear stress. ATP content, the degree of mitochondrial permeability transition pore (MPTP) opening, mitochondrial membrane potential (MMP), and muscle fiber diameter and area showed a gradual downward trend, and myofibril fragmentation index (MFI) and the gap between muscle cells showed an opposite trend. During 6 to 24 h after slaughter, the expression of HIF-1α and the content of NO in the NH4Cl treatment group were significantly higher than those in the control group (P < 0.05), which were significantly higher than those in the L-NAME treatment group (P < 0.05). The ATP content in the NH4Cl group was significantly higher than that in the control and L-NAME groups during 6 to 72 h after slaughter. The activities of Na+-K+-ATPase and Ca2+-ATPase in the control group were significantly higher than those in the NH4Cl group (P < 0.05), but significantly lower than those in the L-NAME group (P < 0.05). During 6–120 h after slaughter, the opening of MPTP in the control group was significantly higher than that in the NH4Cl group (P < 0.05), but lower than that in the L-NAME group (P < 0.05). During 0 to 168 h after slaughter, the opening of MMP decreased by 47.72% in the NH4Cl group, 53.54% in the control group, and 60.05% in the L-NAME group. During 6 to 72 h after slaughter, the activities of caspase-9 and caspase-3 in the NH4Cl group were significantly lower than those in the control group (P < 0.05), which were lower than those in the L-NAME group (P < 0.05). During 6 to 120 h after slaughter, shear force and muscle fiber area and diameter in the NH4Cl group were higher than those in the control group, and MFI and the gap between muscle fibers in the NH4Cl group were lower than those in the control group, while the opposite result was observed for the L-NAME group. In conclusion, ammonia decreased the activities of Na+-K+-ATPase and Ca2+-ATPase and increased the content of ATP by up-regulating the expression of HIF-1α, which in turn regulated the energy metabolism of muscle cells and maintained the stability of the internal environment. By inhibiting the opening of MPTP and the decrease in MMP, ammonia reduced the activity of caspase-3/9, and inhibited mitochondrial cell apoptosis, thereby resulting in an increase in shear stress, a decrease in MFI and morphological changes of muscle cells, and finally causing a negative effect on the tenderness of yak meat