[Structure Characteristics and Driving Variables of Epilithic Algae Community in Lhasa River Basin of Qinghai-Tibet Plateau].

In order to explore the characteristics and driving factors of the epilithic algae community in the middle and lower reaches of the Lhasa River, epilithic algae was collected and identified in September 2019, the species composition and spatial distribution were analyzed, and the key environmental factors affecting the epilithic algae community were identified through redundancy analysis. The results indicated that 31 genera of epilithic algae belonging to six phyla were identified, and the average cell density of the epilithic algae was 1.92×106 cells·m-2. The number of species and cell density of the diatom phylum were the largest at each sampling point. The species number and cell density of the epilithic algae were significantly different between the main stream and tributaries. The main stream and tributaries contained relatively small differences in the dominant algae genera, which were Gomphonema, Fragilaria, Cymbella, and Planktolyngbya in the main stream and Gomphonema, Fragilaria, Cymbella, and Oscillatoria in the tributaries. The redundancy analysis revealed that temperature, pH, and dissolved oxygen were the main driving factors affecting the community structure of the dominant genus in the main stream, while HCO3- and flow velocity controlled the community structure of the dominant genus in the tributaries. This study provides basic data and the theoretical basis for the conservation of aquatic ecosystems and water quality management in the middle and lower reaches of the Lhasa River.

[Effects of femoral offset on soft tissue balance in total hip arthroplasty].

OBJECTIVE: To analysis the effects of restoring neck length and femoral calcar of femoral component on the reconstruction of femoral offset and its affection on soft tissue balance in total hip arthroplasty with standard femoral components. METHODS: Sixty-eight patients (71 hips, 30 male and 38 female,ranging in age from 17 to 89 years,with an average of 63.5 years)undergone primary total hip arthroplasty were followed up. The postoperative hip scored according to Harris hip score symtem, and femoral offset,femoral calcar restored as well as neck length of femoral component were measured from the postoperative X-ray image, and the adductor muscle force was measured by Cybex-6000 isokinetic muscle strength testing system. RESULTS: Femoral neck length had highly significant and positive correlation with femoral offset (r = 0.64, P < 0.001), and had more effects on femoral offset than restoring femoral calcar (t = 3.07, P < 0.01), but had no significant difference on postoperative Harris score. The postoperative femoral offset of patients operated for the femoral head osteonecrosis was less than those for the hip osteoarthrosis (t = 2.91, P < 0.01) and the femoral neck fracture (t = 3.31, P < 0.01). The adductor muscle force in patients who restored femoral offset were better than those failed to restore femoral offset. CONCLUSION: There are several factors affecting femoral offset restoration for soft tissue balance in total hip arthroplasty with standard femoral components, among them, the key factor is the neck length of femoral component which is more significant than femoral calar restoration for reconstruction of femoral offset. The role of femoral offset on soft tissue balance in total hip arthroplasty was strengthening the postoperative adductor muscle.