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Biomedical subjects

Ge Sun

Publications and source records attributed to Ge Sun.

8 recordsLinked to original sources
PubMed2006

Phenophases alter the soil respiration-temperature relationship in an oak-dominated forest.

Soil respiration (SR) represents a major component of forest ecosystem respiration and is influenced seasonally by environmental factors such as temperature, soil moisture, root respiration, and litter fall. Changes in these environmental factors correspond with shifts in plant phenology. In this study, we examined the relationship between canopy phenophases (pre-growth, growth, pre-dormancy, and dormancy) and SR sensitivity to changes in soil temperature (T(S)). SR was measured 53 times over 550 days within an oak forest in northwest Ohio, USA. Annual estimates of SR were calculated with a Q(10) model based on T(S) on a phenological (PT), or annual timescale (AT), or T(S) and soil volumetric water content (VWC) on a phenological (PTM) or annual (ATM) timescale. We found significant (p<0.01) difference in apparent Q(10) from year 2004 (1.23) and year 2005 (2.76) during the growth phenophase. Accounting for moisture-sensitivity increased model performance compared to temperature-only models: the error was -17% for the ATM model and -6% for the PTM model. The annual models consistently underestimated SR in summer and overestimated it in winter. These biases were reduced by delineating SR by tree phenophases and accounting for variation in soil moisture. Even though the bias of annual models in winter SR was small in absolute scale, the relative error was about 91%, and may thus have significant implications for regional and continental C balance estimates.

Models, Theoretical↗
PubMed2005

[Response of sediment production to land-use change in Luergou watershed of Loess Plateau].

The study on the effects of different land use patterns on the sediment production in Luergou watershed of Loess Plateau indicated that in comparing with 1982, the areas of forest and grass and of terrace in 1989 increased by 5% and 2.09%, respectively, while that of slope plowland decreased by 1.5%, with the area of naked land and shrubbery respectively increased and decreased a little. During 1998 - 2000, with the increase of vegetation cover and the decrease of steep slope plowland, the sediment production reduced significantly under high precipitation, 85326 and 52937 t under the precipitation of 803 and 786 mm, respectively, and not distinguishable in dry years. The reduction effect had a strong seasonality, which consisted with rainfall distribution. For example, in a month with 50 mm precipitation, the mean daily sediment concentration was reduced by 6 kg x m(-3), while in a month with 100 mm precipitation, the reduction was 12 kg x m(-3). Rainfall intensity also played an important role in soil erosion and sediment production, regardless of land use conditions.

Conservation of Natural Resources↗
PubMed2004

The first haramiyoid mammal from Asia.

A lower molar of a haramiyoid mammal is described from the Toutunhe Formation of Liuhuanggou near Urumqi in the southern Junggar Basin, Xinjiang, China. It is referred to Eleutherodon sp., otherwise exclusively known from the Upper Bathonian of England. It is the first record of the order Haramiyida from Asia and the first Mesozoic mammal described from the southern Junggar Basin. Apart from the English specimens of Eleutherodon and Staffia from the Upper Jurassic of East Africa, it is the geologically youngest haramiyoid known. It is the first vertebrate taxon from the Toutunhe Formation that is probably not endemic and lends some support to the dating of the Formation as late Middle Jurassic, probably Bathonian.

Animals↗
PubMed2004

A relict trematosauroid (Amphibia: Temnospondyli) from the Middle Jurassic of the Junggar Basin (NW China).

A temnospondyl ilium from the uppermost Toutunhe Formation (Middle Jurassic, Callovian) of the southern Junggar Basin is described. Among the known temnospondyls it is very unusual in morphology because of its very long and slender shaft. It compares closely only to the ilium of one of the latest known trematosaurids from the Ladinian of southern Germany. The Toutunhe Formation has also yielded vertebrae and skull fragments of temnospondyls which belong to the brachyopid Gobiops from the Upper Jurassic of Mongolia. Brachyopoid ilia do not, however, display a morphology similar to that of the new specimen. It is therefore concluded that this specimen represents a second taxon of temnospondyl from the Toutunhe Formation, which probably represents the latest surviving trematosauroid. The Trematosauroidea, which was hitherto exclusively known from the Lower to early Upper Triassic, therefore joins the Brachyopoidea--and possibly the Capitosauroidea --as another group of temnospondyls which survived the end--Triassic mass extinction.

Amphibians↗
PubMed2004

Change in the body temperature of healthy term infant over the first 72 hours of life.

OBJECTIVE: To determine the range of body temperature in a group of healthy Chinese term neonates over the first 72 hours of life and to assess the influence of body weight, gestational age and route of delivery. METHOD: All 200 consecutive cases of neonates delivered at our hospital from March to August 2001 were included in this retrospective study. Temperatures were measured immediately after delivery, after 30 minutes, 1 hour, 2 hours, 8 hours and 15 hours and on the 2nd and 3rd day. Axillary temperatures ranging from 36.5 degrees C to 37 degrees C were regarded as normal. No cases of maternal fever or systemic infection of the newborns were discovered. All infants were discharged in good general condition. RESULTS: The mean rectal temperature at birth was 37.19 degrees C. The lowest average temperature was reached at 1 hour after delivery (36.54 degrees C) with a significant difference between natural delivery (36.48 degrees C) and section (36.59 degrees C) (P<0.05). Temperature subsequently rose to 36.70 degrees C at 8 hours and 36.78 degrees C at 15 hours (P<0.05). Hypothermia was seen in 51.8% and hypothermia in 42.5% of the patients. On the 3rd day after delivery, 96% of all temperatures were in the normal range. A significant relation was found between hypothermia and both low birth weight (P<0.001) and low gestational age (P<0.05). CONCLUSION: The reference range presently used did not include all physiological temperatures in the first 72 hours of life. Considering other factors, such as birth weight, route of delivery, gestational age and body temperature on the 2nd and 3rd day of life, may help to correctly assess the significance of temperatures beyond the reference range.

Adaptation, Physiological↗
PubMed2002

Archaefructaceae, a new basal angiosperm family.

Archaefructaceae is proposed as a new basal angiosperm family of herbaceous aquatic plants. This family consists of the fossils Archaefructus liaoningensis and A. sinensis sp. nov. Complete plants from roots to fertile shoots are known. Their age is a minimum of 124.6 million years from the Yixian Formation, Liaoning, China. They are a sister clade to all angiosperms when their characters are included in a combined three-gene molecular and morphological analysis. Their reproductive axes lack petals and sepals and bear stamens in pairs below conduplicate carpels.

China↗