APF-S2T: Steering to Target Redirection Walking Based on Artificial Potential Fields.

Redirected walking (RDW) enables users to walk naturally within a virtual environment that is larger than the physical environment. Recently, several artificial potential field (APF) and alignment-based redirected controllers have been developed and have been demonstrated to significantly outperform conventional controllers. APF Steer-to-Gradient (APF-S2G) and APF Redirected Walking (APF-RDW) utilize the negative gradient and the total force vector, respectively, which are localized to the user's position. These vectors usually point towards the opposite wall when the user is in corridors, resulting in frequent resets within those regions. This paper introduces the APF Steer-to-Target (APF-S2T), a redirected controller that first finds the target sample point with the lowest score in the user's walkable area in both physical and virtual environments. The score of a sample point is determined by the APF value at the point and the distance from the user's position. The direction from the user's position to the target point is then used as the steering direction for setting RDW gains. We conducted a simulation-based evaluation to compare APF-S2T, APF-S2G, APF-RDW, Visibility Polygon-based alignment (Vis.-Poly.) and Alignment-Optimized controllers in terms of the number of resets and the average distance between resets. The results indicated that APF-S2T significantly outperformed the state-of-the-art controllers.

[Learning and Memory Capacity and NMDA Receptor Expression in Shen Deficiency Constitution Rats].

OBJECTIVE: To explore material bases and neurobiological mechanisms of "Shen storing will" by observing learning and memory capacities and N-methyl-D-aspartic acid (NMDA) receptor expressions in Shen deficiency constitution (SDC) rats. METHODS: Totally 40 SD rats were randomly divided into the model group, the Zuogui Pill (ZP) group, the Yougui Pill (YP) group, the blank control group (consisting of normal pregnant rats), 10 in each group. SDC young rat model (inherent deficiency and postnatal malnutrition) was prepared by the classic way of "cat scaring rat". Medication started when they were scared by cat. Rats in the ZP group and the YP group were administered by gastrogavage with ZP suspension 0.1875 g/mL and YP suspension 0.0938 g/mL respectively. Equal volume of normal saline was administered to rats in the blank control group and the model group by gastrogavage. All medication was given once per day, 5 days in a week for 2 consecutive months. Learning and memory capacities were detected by Morris water maze test. Expressions of NMDA receptor subunits NR2A and NR2B in hippocamus were detected by immunohistochemical method. RESULTS: Compared with the blank control group, the latency period, total distance in Morris water maze test were longer in the model group (P < 0.05). All the aforesaid indices all decreased in the ZP group and the YP group, with statistical difference when compared with the model group (P < 0.05). The protein expressions of NR2A and NR2B in hippocamus were lower in the model group than in the blank control group (P < 0.05). But when compared with the model group, they were obviously higher in the ZP group and the YP group (P < 0.05). CONCLUSIONS: SDC rats had degenerated learning and memory capacities and lowered NMDA receptor expressions. ZP and YP could up-regulate learning and memory capacities and NMDA receptor expressions, thereby improving deterioration of brain functions in SDC rats.

[Qualitative and quantitative methods of betulonic acid in fruits of Liquidambar formosana].

OBJECTIVE: To develop the identification and assay methods for betulonic acid in fruits of Liquidambar formosana. METHOD: TLC method was used for identification with silica gel G plate and petroleum ether(60-90 degrees C)-acetone (17:3) as a developing solvent. Betulonic acid in ethanol extract was separated on the ODS column with methanol-water-glacial acetic acid (87:13:0.1) as mobile phase. Flow-rate was 1.0 mL x min(-1), and column temperature 35 degrees C. ELSD drift-tube temperature was 82 degrees C, and gas flow 1.25 L x min(-1). RESULT: The qualitative method is repeatable. Betulonic acid in ethanol extracts is well separated, relationship of logarithms of injection amount and peak area is linear (r = 0.9997) within the range of 0.65-3.25 microg. The average recovery is 98.0% and RSD of repeatability is 2.5%. 11 crude drugs purchased from different areas in the country were identified and quantified with the methods. CONCLUSION: The methods and data could be used for quality control of fruits of L. formosana.

[Advances of nuclear translation factor:peroxisome proliferator-actived receptor gamma2].

Peroxisome proliferator-actived receptor gamma2(PPARgamma2) is a translation factor that belongs to the superfamily of nuclear receptors. It expresses predominantely in adipose tissue and has a key role in adipocyte differentiation. The common Pro12Ala polymorphism is associated closely with obesity and type 2 diabetes. It is the target molecular of thiazolidinediones which is a novel class of insulin sensitizer. The study of PPARgamma2 molecular mechanism of metabolism control may accelerate the finding of new drug targets in prevention and therapeution of type 2 diabetes.

[Chemical composition of fructus Liquidambaris--lulutong].

AIM: To study the chemical composition in the fruits of Liquidambar formana Hance. METHODS: Various column chromatographic techniques were used to separate and purify the constituents. Their physical and chemical properties and spectral data were measured for structural elucidation. RESULTS: Eleven compounds were isolated and identified as beta-sitosterol (1), 3-oxo-11 alpha, 12 alpha-epoxyleanan-28, 13 beta-olide (2), 3-oxo-12 alpha-hydroxy-oleanan-28, 13 beta-olide (3), 3 alpha-acetyloxy-25-hydroxyolean-12-en-28-oic acid (4), oleanolic acid (5), ursolic acid (6), daucosterol (7), betulonic acid (8), gallic acid (9), nonacosane (10) and n-triacontanoic acid (11). CONCLUSION: Among the isolated constituents, compound 4 is new compound, compound 3 is firstly isolated from the natural product and compound 5, 6, 7, 9, 10 and 11 are isolated from LuLuTong for the first time.