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21.
22.
为探讨西双版纳独特地方气候背景下,热带季节雨林CO2浓度的时空变化特征和不同时间尺度上环境因素对森林CO2浓度时间分布的作用,以及 为研究热带季节雨林的碳通量、净生态系统交换量(Net ecosystem exchange, NEE)等提供支持,我们利用热带季节雨林林冠上方和林内近地层 CO2浓度连续监测资料,结合同步气象资料进行了统计分析。研究结果表明:在植被生理活动、土壤呼吸以及林内湍流的共同作用下,西双版纳 热带季节雨林CO2浓度表现出明显的日变化、季节变化和林冠上下差异。在日尺度上,林冠上方的CO2浓度时间变化曲线为“单峰型”,林内近 地层CO2浓度时间变化曲线为“双峰型”,造成林内近地层傍晚第二个峰值的主要因子是地形因子作用下形成的局地环流。在季节尺度上,林冠 上方CO2浓度主要受林冠代谢作用的影响,呈现雨季低、干季高的特点,而林内近地层的CO2浓度则主要受地表呼吸过程所控制,季节变化趋势 与林冠上方相反。林冠上方CO2浓度低于林内近地层CO2浓度,且差异较大;在日尺度上,各月(除12月外)CO2浓度的最大差值皆大于80 mg·m -3,且出现在傍晚;在季节尺度上,最大值为-62.9 mg·m-3,出现在10月,最小值为-8.4 mg·m-3,出现在12月。 相似文献
23.
Dharmesh S. Kapoor G. Willy Davila Raul J. Rosenthal Gamal M. Ghoniem 《Obesity (Silver Spring, Md.)》2004,12(7):1104-1107
Objective: The objective of this study was to evaluate the impact of obesity on pelvic floor function in women. Research Methods and Procedures: This was a prospective controlled study of 20 morbidly obese female patients planning to undergo gastric bypass surgery and 20 age‐matched female controls. Subjects completed symptom and impact questionnaires, including the Incontinence Impact Questionnaire (IIQ‐7), Urogenital Distress Inventory (UDI), the Kobashi Prolapse Symptom Inventory and Quality‐of‐Life Questionnaire (PSI‐QOL), and Index of Female Sexual Function. Data were analyzed with Wilcoxon or ratio χ2 tests. Results: Mean weight was 295.7 ± 87.9 lbs in the study group and 144.79 ± 33.07 lbs in the control group. Mean BMI was 52.65 ±14.49 kg/m2 in the study group and 25.11 ± 5.27 kg/m2 in the control group. According to the IIQ‐7, urinary incontinence significantly affected lifestyle in the study group. The total IIQ‐7 score was also significantly affected in the study group (p = 0.03). The UDI indicated more urinary leakage with activity (p = 0.04) and more incidents of small amounts of leakage (p = 0.02) in the study group. According to the PSI‐QOL, women in the study group experienced constipation more often because of difficulty in emptying the rectum (p = 0.04). The PSI‐QOL score was higher in the study group (6.75 ± 6.84) than in the control group (2.65 ± 3.03; p = 0.04). There were no significant differences between groups regarding sexual function. Discussion: Morbid obesity is associated with a significant negative impact on urogenital health. Sexual function did not seem to be affected in women who are morbidly obese. 相似文献
24.
Marieke Gorrée Jeroen B. Guinée Gjalt Huppes Lauran van Oers 《The International Journal of Life Cycle Assessment》2002,7(3):158-166
Linoleum is a floor covering consisting mainly of linseed oil, other vegetable oils, wood flour and limestone on a carrier
of jute. Forbo-Krommenie B.V. commissioned the Centre of Environmental Science (CML) to carry out an Environmental Life Cycle
Assessment for linoleum floors. The goal of this study was to assess the environmental performance of linoleum floors, indicating
possible options for improvement, and assessing the sensitivity of the results to methodological choices. The functional unit
was defined as: 2000 m2 linoleum produced in 1998, used in an office or public building over a period of 20 years. The method followed in this study
is based on a nearly final draft version of the LCA guide published by CML in corporation with many others, which is an update
of the guide on LCA of 1992.
From the contribution analysis, the main contributing processes became clear. In addition, the sensitivity analysis by scenarios
showed that the type of maintenance during use and the pigments used can have a large influence on the results. Major data
gaps of the study were capital goods and unknown chemicals. Sensitivity analysis also showed that these gaps can lead to an
underestimation. Based on this study, some options to improve the environmental performance of linoleum were formulated and
advice for further LCA studies on linoleum was given. 相似文献
25.
Callie H. Crawford Zachary S. Randall Pamela B. Hart Lawrence M. Page Prosanta Chakrabarty Apinun Suvarnaraksha Brooke E. Flammang 《Journal of morphology》2020,281(10):1280-1295
The rheophilic hillstream loaches (Balitoridae) of South and Southeast Asia possess a range of pelvic girdle morphologies, which may be attributed to adaptations for locomotion against rapidly flowing water. Specifically, the connectivity of the pelvic plate (basipterygium) to the vertebral column via a sacral rib, and the relative size and shape of the sacral rib, fall within a spectrum of three discrete morphotypes: long, narrow rib that meets the basipterygium; thicker, slightly curved rib meeting the basipterygium; and robust crested rib interlocking with the basipterygium. Species in this third category with more robust sacral rib connections between the basipterygium and vertebral column are capable of walking out of water with a tetrapod-like lateral-sequence, diagonal-couplet gait. This behavior has not been observed in species lacking direct skeletal connection between the vertebrae and the pelvis. The phylogenetic positions of the morphotypes were visualized by matching the morphological features onto a novel hypothesis of relationships for the family Balitoridae. The morphotypes determined through skeletal morphology were correlated with patterns observed in the pelvic muscle morphology of these fishes. Transitions towards increasingly robust pelvic girdle attachment were coincident with a more anterior origin on the basipterygium and more lateral insertion of the muscles on the fin rays, along with a reduction of the superficial abductors and adductors with more posterior insertions. These modifications are expected to provide a mechanical advantage for generating force against the ground. Inclusion of the enigmatic cave-adapted balitorid Cryptotora thamicola into the most data-rich balitorid phylogeny reveals its closest relatives, providing insight into the origin of the skeletal connection between the axial skeleton and basipterygium. 相似文献
26.
We developed an intravaginal instrumented probe (covered with a 10 × 10 matrix of capacitive sensors) for assessing the three-dimensional (3D) spatiotemporal pressure profile of the vaginal canal. The pressure profile was compared to the pelvic floor (PF) digital assessment, and the reliability of the instrument and repeatability of the protocol was tested. We also tested its ability to characterize and differentiate two tasks: PF maximum contraction and Valsalva maneuver (maximum intra-abdominal effort with downward movement of the PF). Peak pressures were calculated for the total matrix, for three major sub-regions, and for 5 planes and 10 rings throughout the vaginal canal. Intraclass correlation coefficients indicated excellent inter- and intra-rater reliability and intra-trial repeatability for the total and medial areas, with moderate reliability for the cranial and caudal areas. There was a moderate correlation between peak pressure and PF digital palpation [Spearman’s coefficient r = 0.55 (p < 0.001)]. Spatiotemporal profiles were completely different between tasks (2-way ANOVAs for repeated measures) with notably higher pressures (above 30 kPa) for the maximum contraction task compared to Valsalva (below 15 kPa). At maximum contraction, higher pressures occurred in the mid-antero-posterior zone, with earlier peak pressure onsets and more variable along the vaginal depth (from rings 3 to 10-caudal). During Valsalva, the highest pressures were observed in rings 4–6, with peak pressure onsets more synchronized between rings. With this protocol and novel instrument, we obtained a high-resolution and highly reliable innovative 3D pressure distribution map of the PF capable of distinguishing vaginal sub-regions, planes, rings and tasks. 相似文献
27.
P. Martins B. Calvo M. Doblaré T. Mascarenhas R. Natal Jorge 《Computer methods in biomechanics and biomedical engineering》2013,16(3):327-337
The mechanical properties of the vaginal tissue need to be characterised to perform accurate simulations of prolapse and other pelvic disorders that commonly affect women. This is also a fundamental step towards the improvement of therapeutic techniques such as surgery. Issues like the efficiency of using autologous tissue in pelvic reconstruction may be addressed. The goal of this study was to characterise the elastic behaviour of vaginal tissue. For this purpose, prolapsed vaginal tissue from eight different post-menopausal patients, excised during prolapse corrective surgery, was mechanically tested. The mechanical testing of vaginal tissue, consisting of uniaxial tension tests performed along the longitudinal axis of the vagina, revealed the nonlinear mechanical behaviour of the tissue. The material model parameters were fit to the experimental data using the Levenberg–Marquardt optimisation algorithm. All the curve fittings showed a good agreement between experimental and theoretical results, evidenced by R 2 values close to 1 and by very low ? values. 相似文献
28.
Pelvis morphology suggests that early Mesozoic birds were too heavy to contact incubate their eggs 下载免费PDF全文
Numerous new fossils have driven an interest in reproduction of early birds, but direct evidence remains elusive. No Mesozoic avian eggs can be unambiguously assigned to a species, which hampers our understanding of the evolution of contact incubation, which is a defining feature of extant birds. Compared to living species, eggs of Mesozoic birds are relatively small, but whether the eggs of Mesozoic birds could actually have borne the weight of a breeding adult has not yet been investigated. We estimated maximal egg breadth for a range of Mesozoic avian taxa from the width of the pelvic canal defined by the pubic symphysis. Known elongation ratios of Mesozoic bird eggs allowed us to predict egg mass and hence the load mass an egg could endure before cracking. These values were compared to the predicted body masses of the adult birds based on skeletal remains. Based on 21 fossil species, we show that for nonornithothoracine birds body mass was 187% of the load mass of the eggs. For Enantiornithes, body mass was 127% greater than the egg load mass, but some early Cretaceous ornithuromorphs were 179% heavier than their eggs could support. Our indirect approach provides the best evidence yet that early birds could not have sat on their eggs without running the risk of causing damage. We suggest that contact incubation evolved comparatively late in birds. 相似文献
29.
Assessment of soil calcium status in red spruce forests in the northeastern United States 总被引:1,自引:1,他引:0
GREGORY B. LAWRENCE MARK B. DAVID SCOTT W. BAILEY WALTER C. SHORTLE 《Biogeochemistry》1997,38(1):19-39
Long-term changes in concentrations of available Ca in soils of redspruce forests have been documented, but remaining questions aboutthe magnitude and regional extent of these changes have precluded anassessment of the current and future status of soil Ca. To addressthis problem, soil samples were collected in 1992—93from 12 sites in New York, Vermont, New Hampshire, and Maine toprovide additional data necessary to synthesize all availableresearch results on soil Ca in red spruce forests. Sites werechosen to encompass the range of environmental conditionsexperienced by red spruce. Concentrations of exchangeableCa ranged from 2.13 to 21.6 cmolckg–1 in the Oa horizon, and from 0.11 to 0.68cmolc kg–1 in the upper 10 cm of theB horizon. These measurements expanded the range of exchangeable Ca reported in the literature for both horizons in northeastern redspruce forests. Exchangeable Ca was the largest Ca fraction in theforest floor at most sites (92% ofacid-extractableCa), but mineral Ca was the largest fraction at the three sites that also had the highest mineral-matter concentrations. Theprimary factor causing variability in Ca concentrations among siteswas the mineralogy of parent material, but exchangeable concentrationsin the B horizon of all sites were probably reduced by acidicdeposition. Because the majority of Ca in the forest floor isin a readily leachable form, and Ca inputs to the forest floor from the mineral soil and atmospheric deposition have beendecreasing in recent decades, the previously documented decreasesin Ca concentrations in the forest floor over previous decades mayextend into the future. 相似文献
30.
Paired fins and associated internal structures of the epauletic sharkHemiscyllium ocellatum, were described on the basis of three specimens. A comparison with other genera showed the epaulette shark to be, characterized
by two elongated basal cartilages articulating with a distally projecting articular condyle on the coracoid, a loosely separated
radial series with an intermediate series, a levator pectoralis inferior muscle and an anterolaterally developed depressor
pectoralis muscle in the pectoral fin, and an elongated anterior pelvic basal cartilage articulating with a distally projecting
articular condyle and an anterolaterally developed depressor pelvicus muscle in the pelvic fin. In captivity, the sharks exhibited
both upright and crawling behavior on the bottom by using the pectoral and pelvic fins and bending the body. The distinctive
morphological characters are shared by otherHemiscyllium species and are suggested as important factors enabling their unique behavior associated with a complex coral reef habitat. 相似文献