AIM: To investigate the effects of body mass index (BMI) on intraocular pressure (IOP) and ocular pulse amplitude(OPA). METHODS: Totally 140 healthy individuals without any systemic diseases were included in the study...AIM: To investigate the effects of body mass index (BMI) on intraocular pressure (IOP) and ocular pulse amplitude(OPA). METHODS: Totally 140 healthy individuals without any systemic diseases were included in the study. BMI (kg/m2) was calculated for every individual. IOP and OPA were measured with Pascal Dynamic contour tonometer (DCT). Blood pressure was also measured along with the DCT. The patients were divided into three groups according to BMI as: Group1, BMI<25; Group2, 25≤BMI<30; Group3, BMI≥30. Mean values of IOP, OPA, systolic blood pressure (SBP) and diastolic blood pressure (DBP) were used in statistical analysis.RESULTS: In Group1, the means of IOP, OPA, were 16.8±2.3mmHg, 2.7±0.7mmHg respectively; and SBP, DBP were 120.0±6.1mmHg, and 77.4±5.6mmHg respectively. In group2, the mean IOP, OPA, SBP, and DBP were found to be 16.6±2.1mmHg, 2.4±0.7mmHg, 121.7±5.3mmHg, and 79.5±4.9mmHg respectively. In group3, the mean IOP, OPA, SBP, and DBP were found to be 17.3±1.7mmHg, 2.1±0.7mmHg, 122.4±5.7mmHg, and 79.7±5.2mmHg respectively. There were no statistically significant difference between groups in terms of IOP, SBP and DBP, while OPA values were significantly lower in group3 (P=0.001). CONCLUSION: Decreased OPA values in individuals with higher BMI may indicate that subjects with higher BMI have lower choroidal perfusion and lower ocular blood flow.展开更多
Vapor pressure deficit(VPD)plays a crucial role in determining plant physiological functions and exerts a substantial influence on vegetation,second only to carbon dioxide(CO_(2)).As a robust indicator of atmospheric ...Vapor pressure deficit(VPD)plays a crucial role in determining plant physiological functions and exerts a substantial influence on vegetation,second only to carbon dioxide(CO_(2)).As a robust indicator of atmospheric water demand,VPD has implications for global water resources,and its significance extends to the structure and functioning of ecosystems.However,the influence of VPD on vegetation growth under climate change remains unclear in China.This study employed empirical equations to estimate the VPD in China from 2000 to 2020 based on meteorological reanalysis data of the Climatic Research Unit(CRU)Time-Series version 4.06(TS4.06)and European Centre for Medium-Range Weather Forecasts(ECMWF)Reanalysis 5(ERA-5).Vegetation growth status was characterized using three vegetation indices,namely gross primary productivity(GPP),leaf area index(LAI),and near-infrared reflectance of vegetation(NIRv).The spatiotemporal dynamics of VPD and vegetation indices were analyzed using the Theil-Sen median trend analysis and Mann-Kendall test.Furthermore,the influence of VPD on vegetation growth and its relative contribution were assessed using a multiple linear regression model.The results indicated an overall negative correlation between VPD and vegetation indices.Three VPD intervals for the correlations between VPD and vegetation indices were identified:a significant positive correlation at VPD below 4.820 hPa,a significant negative correlation at VPD within 4.820–9.000 hPa,and a notable weakening of negative correlation at VPD above 9.000 hPa.VPD exhibited a pronounced negative impact on vegetation growth,surpassing those of temperature,precipitation,and solar radiation in absolute magnitude.CO_(2) contributed most positively to vegetation growth,with VPD offsetting approximately 30.00%of the positive effect of CO_(2).As the rise of VPD decelerated,its relative contribution to vegetation growth diminished.Additionally,the intensification of spatial variations in temperature and precipitation accentuated the spatial heterogeneity in the impact of VPD on vegetation growth in China.This research provides a theoretical foundation for addressing climate change in China,especially regarding the challenges posed by increasing VPD.展开更多
Septic shock is a common critical condition, for which effective early fluid resuscitation is the therapeutic focus. According to the 2008 international guidelines for management of severe sepsis and septic shock, res...Septic shock is a common critical condition, for which effective early fluid resuscitation is the therapeutic focus. According to the 2008 international guidelines for management of severe sepsis and septic shock, resuscitation should achieve a central venous pressure (CVP) of 8-12 mmHg within the first 6 h. However, it is still uncertain about the sensitivity and specificity of CVP in reflecting the cardiac preload. Ultrasonography is a simple, rapid, non-invasive, and repeatable method for the measurement of sensitivity and specificity of CVP and has thus gradually attracted the increasing attention of physicians. It was reported that ultrasonography can show the inferior vena cava diameter, respiratory variability index, and blood volume in patients with sepsis or heart failure.展开更多
Objective:The aim of the study was to evaluate the quality of sleep in nurses performing shift work in therapeutic and surgical depar tments and to establish possible relationships between level of blood pressure(BP)a...Objective:The aim of the study was to evaluate the quality of sleep in nurses performing shift work in therapeutic and surgical depar tments and to establish possible relationships between level of blood pressure(BP)and quality of sleep.Methods:A total of 20 nurses of the therapeutic depar tments and 20 nurses of the surgical depar tments were enrolled in the study.Sleep quality was assessed using the Pittsburgh Sleep Quality Index(PSQI).BP was measured according to the standard protocol using the Korotkoff method;a sphygmomanometer was used for this twice with an interval of 2 min between 10:00 a.m.and 10:30 a.m.The average value for the 2 indicators was calculated.The diagnosis of essential ar terial hyper tension(AH)was established according to the recommendations of the European Association of Cardiology and the European Association of Hypertension(2018).Results:The overall assessment of the sleep quality of the nurses involved in shift work indicates poor sleep quality;this was true in respondents of both the surgical and therapeutic profiles.However,it was observed that the quality of sleep was significantly lower in nurses of the therapeutic departments.Moreover,poor sleep quality was associated with AH,which was diagnosed in 65%of the nurses of the therapeutic departments and 45%of the nurses of the surgical departments,that is,in almost all of the subjects.Herewith,in the nurses of the therapeutic departments,the level of systolic BP exceeded that of the nurses of the surgical departments.Conclusions:Poor sleep quality is a significant risk factor for AH development and is relevant to nurses performing shift work.Additional clinical studies should be conducted to better understand the mechanisms underlying such adverse cardiometabolic outcomes associated with sleep disorders in the health-sector shift workers.展开更多
Objective To determine whether reduction in central pressure augmentation and central systolic blood pressure by nitroglycerine (NTG) results from effects on pre-load or is due to arterial dilation. Methods We compare...Objective To determine whether reduction in central pressure augmentation and central systolic blood pressure by nitroglycerine (NTG) results from effects on pre-load or is due to arterial dilation. Methods We compared effects of NTG with those of lower body negative pressure (LBNP). Hemodynamic measurements were made at rest,during LBNP (10,20 and 30 mmHg,each for 15 min) and after NTG (10,30 and 100 μg/min,each dose for 15 min) in ten healthy volunteers. Cardiac pre-load,stroke volume and cardiac output were assessed by echocardiography. Central pressure augmentation and central systolic pressure were obtained by radial tonometry using a transfer function. Results LBNP (20 mmHg) and NTG (30 μg/min) reduced pre-load (as measured by the peak velocity of the S wave in the superior vena cava) to a similar degree [by (26.8±3.8)% and (23.9±3.4)%,respectively]. Compared to LBNP,NTG reduced systemic vascular resistance [by (32.9±7.5)%,P<0.01],decreased peripheral and central pressure augmentation [by (20.8±3.4)% units and (12.9±2.9)% units,respectively,each P<0.01]. Conclusion These results suggest that a reduction in pre-load does not explain reduction in pressure augmentation and central systolic blood pressure by NTG and that these effects are mediated through arterial dilation.展开更多
Background: The ankle/brachial pressure index (ABPI) has been shown to be a good marker of systemic atherosclerosis and a powerful predictor of cardiovascular morbidity and mortality. The objective of this study was t...Background: The ankle/brachial pressure index (ABPI) has been shown to be a good marker of systemic atherosclerosis and a powerful predictor of cardiovascular morbidity and mortality. The objective of this study was to determine the importance of measuring ABPI in Saudi patients with coronary artery disease (CAD). METHODS: This is a hospital based cross-sectional study which was conducted on all Saudi patients who underwent coronary angiography without symptoms of peripheral arterial disease at King Fahd Hospital of the University, Al-Khobar Saudi Arabia. All patients underwent measurement of their ABPI. The study was carried out between December 2010 and November 2011. RESULTS: During the study period, two hundred and five patients were included. Fifty-nine (28.8%) patients were Group II (ABPI ≤ 0.90) and the rest was Group I (ABPI > 0.90). Significant correlation was also found between low ABPI and the extent of CAD (mean number of arteries involved in Group I was 1.78 ± 0.83 compared to 2.10 ± 0.736 in Group II p = 0.011). Nevertheless, the correlation between low ABPI, and the severity of presentation of CAD were also significant (Incidence of myocardial infarction with congestive heart failure was 0.5% in Group I compared to 12% in Group II p CONCLUSION: The ABPI is an important prognostic indicator for Saudi patients with CAD.展开更多
Background: In new outpatients, blood pressure should be measured in both arms. A previous study reported that an inter-arm systolic blood pressure difference (ΔSBP) of ≥10 mm Hg is associated with an increased risk...Background: In new outpatients, blood pressure should be measured in both arms. A previous study reported that an inter-arm systolic blood pressure difference (ΔSBP) of ≥10 mm Hg is associated with an increased risk of mortality. Aim: The aim was to identify the associations with absolute values of ΔSBP (|ΔSBP|) ≥10 mm Hg. Subjects and Methods: This study included 2481 patients. Patients with a body mass index ≥25 kg/m<sup>2</sup> were defined as obese. The group of A was defined as following: ankle-brachial index (ABI) was <0.9 or ≥1.3. ΔSBP was expressed as right arm BP minus left arm BP. |ΔSBP| ≥10 mm Hg were analyzed using multivariate logistic analysis. Results: |ΔSBP| ≥10 mm Hg was found in 6.0% of patients and |ΔSBP| < 5 mm Hg in 80.4%. In multivariate analysis, the odds ratios (ORs) of the associations with |ΔSBP| ≥10 mm Hg were significantly associated with abnormal ABI and obesity regardless of sex and age. Moreover, the OR of the combined effects of abnormal ABI and obesity was higher than that of abnormal ABI and obesity alone. Conclusion: |ΔSBP| ≥10 mm Hg was associated with abnormal ABI and obesity. In a primary care setting, blood pressure should be actively measured in both arms. This study suggests that the associations with |ΔSBP| ≥10 mm Hg may be a useful part of screening for abnormal ABI.展开更多
By analyzing hundreds of capillary pressure curves, the controlling factors of shape and type of capillary pressure curves are found and a novel method is presented to construct capillary pressure curves by using rese...By analyzing hundreds of capillary pressure curves, the controlling factors of shape and type of capillary pressure curves are found and a novel method is presented to construct capillary pressure curves by using reservoir permeability and a synthesized index. The accuracy of this new method is verified by mercury-injection experiments. Considering the limited quantity of capillary pressure data, a new method is developed to extract the Swanson parameter from the NMR T2 distribution and estimate reservoir permeability. Integrating with NMR total porosity, reservoir capillary pressure curves can be constructed to evaluate reservoir pore structure in the intervals with NMR log data. An in-situ example of evaluating reservoir pore structure using the capillary pressure curves by this new method is presented. The result shows that it accurately detects the change in reservoir pore structure as a function of depth.展开更多
The main goal of spinal cord rehabilitation is to restore walking ability and improve walking quality after spinal cord injury(SCI). The spatiotemporal parameters of walking and the parameters of plantar pressure can ...The main goal of spinal cord rehabilitation is to restore walking ability and improve walking quality after spinal cord injury(SCI). The spatiotemporal parameters of walking and the parameters of plantar pressure can be obtained using a plantar pressure analysis system. Previous studies have reported step asymmetry in patients with bilateral SCI. However, the asymmetry of other parameters in patients with SCI has not been reported. This was a prospective, cross-sectional study, which included 23 patients with SCI, aged 48.1 ± 14.5 years, and 28 healthy subjects, aged 47.1 ± 9.8 years. All subjects underwent bare foot walking on a plantar pressure measurement device to measure walking speed and spatiotemporal parameters. Compared with healthy subjects, SCI patients had slower walking speed, longer stride time and stance time, larger stance phase percentage, and shorter stride length. The peak pressures under the metatarsal heads and toe were lower in SCI patients than in healthy subjects. In the heel, regional impulse and the contact area percentage in SCI patients were higher than those in healthy subjects. The symmetry indexes of stance time, step length, maximum force, impulse and contact area were increased in SCI patients, indicating a decline in symmetry. The results confirm that the gait quality, including spatiotemporal variables and plantar pressure parameters, and symmetry index were lower in SCI patients compared with healthy subjects. Plantar pressure parameters and symmetry index could be sensitive quantitative parameters to improve gait quality of SCI patients. The protocols were approved by the Clinical Research Ethics Committee of Shengjing Hospital of China Medical University(approval No. 2015 PS54 J) on August 13, 2015. This trial was registered in the ISRCTN Registry(ISRCTN42544587) on August 22, 2018. Protocol version: 1.0.展开更多
This paper presents the evolution process of pressure angles from planar parallel mechanisms to spatial parallel mechanisms. Manipulability and condition number, which are frequently used in the optimum design of para...This paper presents the evolution process of pressure angles from planar parallel mechanisms to spatial parallel mechanisms. Manipulability and condition number, which are frequently used in the optimum design of parallel mechanisms, are introduced from serial robots at first. Then, both theoretical analysis and practical experiences demonstrate that these concepts seem imperfect when they are used in parallel mechanisms. For this reason, this paper introduces the pressure angles in planar 4-bar mechanisms to spatial parallel mechanisms, which include redundant parallel mechanisms. Two kinds of pressure angles extracted from the determinant of direct and indirect Jacobian matrices are investigated. Moreover, two comprehensive and visible global performance indices are defined, showing the advantages in evaluating the workspace, singularity and motion/force transmission capabilities. With a 2-DOF planar and a 3-DOF spatial parallel mechanism as examples, the application of the performance indices is investigated and compared with the condition number at last. The proposed concept can be extended to other spatial parallel mechanisms.展开更多
To evaluate vital signs and body indices in Helicobacter pylori (H. pylori) positive and negative persons. A total of 22 centres entered the study. They were spread over the whole country, corresponding well to the ge...To evaluate vital signs and body indices in Helicobacter pylori (H. pylori) positive and negative persons. A total of 22 centres entered the study. They were spread over the whole country, corresponding well to the geographical distribution of the Czech population. A total of 1818 subjects (aged 5-98 years) took part in the study, randomly selected out of 38147 subjects. H. pylori infection was investigated by means of a 13C-urea breath test. Data on height, weight, systolic and diastolic blood pressure and heart rate were collected at the clinics of general practitioners. The overall prevalence of H. pylori infection was 30.4% (402/1321) in adults (≥ 18 year-old) and 5.2% (26/497) in children and adolescents (≤ 17 year-old). Once adjusted for age and gender, only a difference in body mass index remained statistically significant with H. pylori positive adults showing an increase of 0.6 kg/m<sup>2</sup> in body mass index. Once adjusted for age and gender, we found a difference in height between H. pylori positive and H. pylori negative children and adolescents. On further adjustment for place of residence, this difference became statistically significant, with H. pylori positive children and adolescents being on average 3.5 cm shorter. H. pylori positive adults were significantly older compared to H. pylori negative subjects. Once adjusted for age and gender, H. pylori infection had no impact on body weight, body mass index and vital signs either in adults or children and adolescents. Chronic H. pylori infection appeared to be associated with short stature in children. H. pylori infection did not influence blood pressure, body weight and body mass index either in adults or children and adolescents.展开更多
The paper focuses on Cassini oval pressure hulls under uniform external pressure. The Cassini oval pressure hull is proposed based on the shape index of Cassini oval. The buckling of a series of Cassini oval pressure ...The paper focuses on Cassini oval pressure hulls under uniform external pressure. The Cassini oval pressure hull is proposed based on the shape index of Cassini oval. The buckling of a series of Cassini oval pressure hulls with the shape index of 0.09–0.30 and one spherical pressure hull with the diameter of 2 m is devoted. Such hulls are numerically studied in the case of constant volume, material properties, and wall thickness. The results show that Cassini oval pressure hulls with the shape index of 0.10–0.11 can resist about 4% more external pressure than the spherical one. This deviates from the classical mechanics conclusion that spherical shell is the optimal shape for underwater pressure resistant structures.展开更多
Effects of continuous negative pressure water supply on water consumption, growth and development, as well as physiological mechanism and quality of Capsicum annuum L. were investigated in this paper. Meanwhile, the o...Effects of continuous negative pressure water supply on water consumption, growth and development, as well as physiological mechanism and quality of Capsicum annuum L. were investigated in this paper. Meanwhile, the optimal negative pressure water supply conditions for growth of C. annuum L. were screened out to achieve the goals of water conservation, high yield and high quality, thus providing theoretical foundation for its field production. The pot experiment within the greenhouse was utilized; the continuous negative pressure water supply was adopted; the four treatments, artificial watering(CK), –5 k Pa(T1), –10 k Pa(T2), and –15 k Pa(T3) were set; and the daily water consumption, yield, as well as the biomass, nitrate reductase, root activity, vitamin C, capsaicin, and nutrient uptakes of nitrogen(N), phosphorus(P) and potassium(K) during various stages of its growth were determined. Compared with CK, when the water supply pressure was controlled at –5 to –15 k Pa in the experiment, the total water consumption of C. annuum L. reduced by 53.42 to 67.75%, the total water consumption intensity reduced by 54.29 to 67.14%, and the water use efficiency increased by 12.66 to 124.67%. The N accumulation in a single strain of C. annuum L. from the color turning stage to the red ripe stage increased by 15.99 to 100.55%, respectively, compared with that of CK; the P accumulation increased by 20.47 to 154.00% relative to that of CK, and the K accumulation increased by 64.92 to 144.9% compared with that of CK. Compared with CK, C. annuum L. yield was remarkably improved by 13.79% at T1, and contents of vitamin C, capsaicin as well as carotenoids at all growth stages were enhanced by 13.42–147.01%, 11.54–71.01%, and 41.1–568.06%, respectively. Nitrate reductase activity, root activity and chlorophyll(a+b) were markedly increased by 335.78–500%, 79.6–140.68% and 114.95–676.19%, respectively, from immature stage to full ripe stage. Adopting the continuous negative pressure water supply for C. annuum L. has a significant water-saving effect, and the water supply pressure being stable at –5 k Pa contributes to its growth and development, improves yield, enhances root activity, promotes nutrient uptake, and improves its quality, thus achieving the effects of water conservation, high yield, high quality and high efficiency.展开更多
Objective To estimate the prevalence of elevated blood pressure(EBP) in Chinese children and identify individual and family factors associated with EBP. Methods A nationwide cross-sectional study was conducted in 20...Objective To estimate the prevalence of elevated blood pressure(EBP) in Chinese children and identify individual and family factors associated with EBP. Methods A nationwide cross-sectional study was conducted in 2010 using stratified cluster sampling. Participants' blood pressure was measured, and their parents completed a questionnaire on personal and family characteristics. Prevalence and correlates of EBP were assessed. Results Among a total of 24,333 participants, 20.2% of boys and 16.3% of girls had EBP. The prevalence of EBP increased with the ascending trend of waist circumference, Waist-to-height ratio, and body mass index. The adjusted prevalence ratios(aP Rs) for obese boys and girls were 2.50 and 2.97, respectively. Fewer urban boys(16.2%) had EBP than rural boys(21.7%). Boys with a family history of hypertension were 12% more likely to have EBP. Children whose mothers received a college education tended to have lower likelihood of EBP; with an aP R was 0.85 among boys and 0.78 among girls. Conclusion EBP is common among obese students and those who have a family history of hypertension. A negative association between mothers' education levels and EBP risk in children was found.展开更多
AIM:To evaluate the correlation between intraocular pressure(IOP)and various obesity-related health factors in patients with ocular hypertension in Korea.METHODS:A total of 40850 subjects underwent age,sex,body weight...AIM:To evaluate the correlation between intraocular pressure(IOP)and various obesity-related health factors in patients with ocular hypertension in Korea.METHODS:A total of 40850 subjects underwent age,sex,body weight,and height assessments and automated multiphasic tests,including non-contact tonometry,automated perimetry,fundus photography,systolic/diastolic blood pressure measurement,and evaluation of obesity-related health parameters such as obesity index,body mass index(BMI),a body shape index(ABSI),and waist-to-height ratio(WtHR).Subjects were divided into ocular hypertension group and normal IOP group according to IOP after matching of age and sex.RESULTS:Of 40850 participants,1515(3.7%)had ocular hypertension,and 1515 with normal IOP were selected as controls using propensity score matching.The mean IOP of control group was 15.3±2.3 mm Hg,compared with 23.3±1.6 mm Hg in ocular hypertension group.Height,obesity index,BMI,and WtHR in the ocular hypertension group were significantly higher than in the normal IOP group(P<0.001,P<0.001,P=0.009,P=0.002).IOP of ocular hypertension was positively correlated with obesity index(P=0.027)and BMI(P=0.016),whereas IOP of control was positively correlated with blood pressure(P<0.001,P=0.002),obesity index(P<0.001),BMI(P<0.001),and WHtR(P=0.002).Systolic blood pressure(β=0.022,P<0.001)and body weight(β=0.016,P=0.02)were precursors of IOP in normal subjects,but sex(male;β=-0.231,P=0.008)and obesity index(β=-0.007,P=0.017)were precursors of ocular hypertension according to multiple regression analysis.CONCLUSION:Among various obesity-related health parameters,obesity index is the best indicator for further increase in IOP in ocular hypertension group.展开更多
Rock typing is an important tool in evaluation and performance prediction of reservoirs.Different techniques such as flow zone indicator(FZI),FZI~*and Winland methods are used to categorize reservoir rocks into distin...Rock typing is an important tool in evaluation and performance prediction of reservoirs.Different techniques such as flow zone indicator(FZI),FZI~*and Winland methods are used to categorize reservoir rocks into distinct rock types.Generally,these methods are applied to petrophysical data that are measured at a pressure other than reservoir pressure.Since the pressure changes the pore structure of rock,the effect of overburden pressure on rock typing should be considered.In this study,porosity and permeability of 113 core samples were measured at five different pressures.To investigate the effect of pressure on determination of rock types,FZI,FZI~*and Winland methods were applied.Results indicated that although most of the samples remain in the same rock type when pressure changes,some of them show different trends.These are related to the mineralogy and changes in pore system of the samples due to pressure change.Additionally,the number of rock types increases with increasing pressure.Furthermore,the effect of overburden pressure on determination of rock types is more clearly observed in the Winland and FZI~*methods.Also,results revealed that a more precise reservoir dynamic simulation can be obtained by considering the reservoir rock typing process at reservoir conditions.展开更多
In this paper,we study the interactive relationship between the agglomeration of urban elements and the evolution of eco-environmental pressure.We build an index system for evaluating the agglomeration of urban elemen...In this paper,we study the interactive relationship between the agglomeration of urban elements and the evolution of eco-environmental pressure.We build an index system for evaluating the agglomeration of urban elements and eco-environmental pressure.Using the entropy method and response intensity model,we analyze how urban elements agglomeration influenced eco-environmental pressure in Changchun from 1990 to 2012,eliciting the changing features and influential factors.Ultimately,we conclude there is a significant interactive relationship between the agglomeration of urban elements and the evolution of eco-environmental pressure in Changchun.This is inferred from the degree of this agglomeration in Changchun having increased since 1990,with the degree of eco-environmental pressure first decreasing and then increasing.Alongside this,the impact of urban elements agglomeration on eco-environmental pressure has changed from negative to positive.The main reasons behind this shift are arguably the rapid growth of urban investment and ongoing urbanization.展开更多
Results of triaxial compression experiment results show that granite rock strength increases with the depth until 30 km. In shallow crust, rock failure exhibits abrupt or quasi-abrupt instability under lower pressure....Results of triaxial compression experiment results show that granite rock strength increases with the depth until 30 km. In shallow crust, rock failure exhibits abrupt or quasi-abrupt instability under lower pressure. Acoustic Emission (AE for short) distributed almost uniformly before and after failure. Go through downwards into the depth range with progressive failure feature, there are no or only a few number of AE before and after failure. In deeper range, rock failure shows some feature of quasi-abrupt instability under high pressure. There are still few AE before failure, but with the stick-slip, much more An events were detected after failure. Under the temperature and pressure condition of more deep crust (about 26 km), rock failure takes abrupt instability under high pressure as main feature, there are dense AE activities before failure and cumulated frequency of AE increases exponentially before the failure. In about 35 km depth range, rock strength decreases quickly with the depth and sample exhibits semi-ductile or ductile progressive fails, there are no AE being detected before and after failure. The b value of AE sequence before failure seems a little smaller than that after failure, and b value roughly decreased with depth. The numerical range of index α is the widest in about 18 km depth and becomes narrow in the condition of more shallow or more deep crust. So, when the temperature and pressure condition simulating the real environment of focal depth changes from shallow to deep in the crust, the range of a of microfracture sequence would undergo such an evolvement process that a changes from narrow to wide and then to narrow again.展开更多
Based on the introduction of the general situation of research region,pressure index model of cultivated land is adopted according to the data of population,cultivated land area,crop sowing area,grain sowing area,and ...Based on the introduction of the general situation of research region,pressure index model of cultivated land is adopted according to the data of population,cultivated land area,crop sowing area,grain sowing area,and unit grain yield in the Statistical Yearbook of Fengxian County.The change of relevant factors of cultivated land pressure index over time is analyzed,as well as the tension level of cultivated land resources.Research shows that the pressure on cultivated land is relatively great in Fengxian County in the years 1999-2005.Grain supply and demand is still under the unsafe state.There will be more prominent contradiction between supply and demand of cultivated land in Fengxian County in the future,and the grain security will under greater pressure.Several countermeasures are put forward to ease the pressure on cultivated land in Fengxian County,in order to realize the sustainable use of cultivated land resources,to ensure the supply and demand balance of grain and cultivated land,and to stabilize and improve the grain productivity in Fengxian County,such as protecting the current cultivated land resources by the strictest protection system of cultivated land,enhancing the intensity of land development and reclamation,enlarging the area of cultivated land,increasing the agricultural sci-tech input,and improving the grain unit yield.展开更多
Because of the paucity of serial blood pressure data on the same individuals, little is known about the accuracy of elevated blood pressure (BP) in childhood for predicting hypertension (HBP) later in life. The availa...Because of the paucity of serial blood pressure data on the same individuals, little is known about the accuracy of elevated blood pressure (BP) in childhood for predicting hypertension (HBP) later in life. The availability of long-term serial BP data from the Fels Longitudinal Study (FLS) presents the opportunity to link HBP in adulthood directly to BP measured decades earlier in the same individuals as children. We analyzed serial data from 965 men and 1114 women in the FLS. We used an autoregressive-moving average (1, 1) [ARMA (1, 1)] longitudinal model to predict adult HBP from childhood values. For 15-year-old boys with SBP 15 mmHg and 30 mmHg above the average SBP of 90 mmHg, the probabilities of having HBP at age 35 are 0.18 and 0.33, respectively. The corresponding probabilities for 15-year-old girls are only 0.04 and 0.08. This striking sex difference in risk of HBP at age 35 between 15-year-old boys and girls indicates that the risk of developing HBP in women is low regardless of their childhood blood pressure at any age from 2 to 17 years. Men are about 4.25 times more likely to have HBP at age 35 than women over a range of SBP of 90 - 140 mmHg at age 15. The ARMA (1, 1) model allows the identification of boys at risk for HBP as adult men.展开更多
文摘AIM: To investigate the effects of body mass index (BMI) on intraocular pressure (IOP) and ocular pulse amplitude(OPA). METHODS: Totally 140 healthy individuals without any systemic diseases were included in the study. BMI (kg/m2) was calculated for every individual. IOP and OPA were measured with Pascal Dynamic contour tonometer (DCT). Blood pressure was also measured along with the DCT. The patients were divided into three groups according to BMI as: Group1, BMI<25; Group2, 25≤BMI<30; Group3, BMI≥30. Mean values of IOP, OPA, systolic blood pressure (SBP) and diastolic blood pressure (DBP) were used in statistical analysis.RESULTS: In Group1, the means of IOP, OPA, were 16.8±2.3mmHg, 2.7±0.7mmHg respectively; and SBP, DBP were 120.0±6.1mmHg, and 77.4±5.6mmHg respectively. In group2, the mean IOP, OPA, SBP, and DBP were found to be 16.6±2.1mmHg, 2.4±0.7mmHg, 121.7±5.3mmHg, and 79.5±4.9mmHg respectively. In group3, the mean IOP, OPA, SBP, and DBP were found to be 17.3±1.7mmHg, 2.1±0.7mmHg, 122.4±5.7mmHg, and 79.7±5.2mmHg respectively. There were no statistically significant difference between groups in terms of IOP, SBP and DBP, while OPA values were significantly lower in group3 (P=0.001). CONCLUSION: Decreased OPA values in individuals with higher BMI may indicate that subjects with higher BMI have lower choroidal perfusion and lower ocular blood flow.
基金This research was supported by the National Natural Science Foundation of China(42161058).
文摘Vapor pressure deficit(VPD)plays a crucial role in determining plant physiological functions and exerts a substantial influence on vegetation,second only to carbon dioxide(CO_(2)).As a robust indicator of atmospheric water demand,VPD has implications for global water resources,and its significance extends to the structure and functioning of ecosystems.However,the influence of VPD on vegetation growth under climate change remains unclear in China.This study employed empirical equations to estimate the VPD in China from 2000 to 2020 based on meteorological reanalysis data of the Climatic Research Unit(CRU)Time-Series version 4.06(TS4.06)and European Centre for Medium-Range Weather Forecasts(ECMWF)Reanalysis 5(ERA-5).Vegetation growth status was characterized using three vegetation indices,namely gross primary productivity(GPP),leaf area index(LAI),and near-infrared reflectance of vegetation(NIRv).The spatiotemporal dynamics of VPD and vegetation indices were analyzed using the Theil-Sen median trend analysis and Mann-Kendall test.Furthermore,the influence of VPD on vegetation growth and its relative contribution were assessed using a multiple linear regression model.The results indicated an overall negative correlation between VPD and vegetation indices.Three VPD intervals for the correlations between VPD and vegetation indices were identified:a significant positive correlation at VPD below 4.820 hPa,a significant negative correlation at VPD within 4.820–9.000 hPa,and a notable weakening of negative correlation at VPD above 9.000 hPa.VPD exhibited a pronounced negative impact on vegetation growth,surpassing those of temperature,precipitation,and solar radiation in absolute magnitude.CO_(2) contributed most positively to vegetation growth,with VPD offsetting approximately 30.00%of the positive effect of CO_(2).As the rise of VPD decelerated,its relative contribution to vegetation growth diminished.Additionally,the intensification of spatial variations in temperature and precipitation accentuated the spatial heterogeneity in the impact of VPD on vegetation growth in China.This research provides a theoretical foundation for addressing climate change in China,especially regarding the challenges posed by increasing VPD.
文摘Septic shock is a common critical condition, for which effective early fluid resuscitation is the therapeutic focus. According to the 2008 international guidelines for management of severe sepsis and septic shock, resuscitation should achieve a central venous pressure (CVP) of 8-12 mmHg within the first 6 h. However, it is still uncertain about the sensitivity and specificity of CVP in reflecting the cardiac preload. Ultrasonography is a simple, rapid, non-invasive, and repeatable method for the measurement of sensitivity and specificity of CVP and has thus gradually attracted the increasing attention of physicians. It was reported that ultrasonography can show the inferior vena cava diameter, respiratory variability index, and blood volume in patients with sepsis or heart failure.
文摘Objective:The aim of the study was to evaluate the quality of sleep in nurses performing shift work in therapeutic and surgical depar tments and to establish possible relationships between level of blood pressure(BP)and quality of sleep.Methods:A total of 20 nurses of the therapeutic depar tments and 20 nurses of the surgical depar tments were enrolled in the study.Sleep quality was assessed using the Pittsburgh Sleep Quality Index(PSQI).BP was measured according to the standard protocol using the Korotkoff method;a sphygmomanometer was used for this twice with an interval of 2 min between 10:00 a.m.and 10:30 a.m.The average value for the 2 indicators was calculated.The diagnosis of essential ar terial hyper tension(AH)was established according to the recommendations of the European Association of Cardiology and the European Association of Hypertension(2018).Results:The overall assessment of the sleep quality of the nurses involved in shift work indicates poor sleep quality;this was true in respondents of both the surgical and therapeutic profiles.However,it was observed that the quality of sleep was significantly lower in nurses of the therapeutic departments.Moreover,poor sleep quality was associated with AH,which was diagnosed in 65%of the nurses of the therapeutic departments and 45%of the nurses of the surgical departments,that is,in almost all of the subjects.Herewith,in the nurses of the therapeutic departments,the level of systolic BP exceeded that of the nurses of the surgical departments.Conclusions:Poor sleep quality is a significant risk factor for AH development and is relevant to nurses performing shift work.Additional clinical studies should be conducted to better understand the mechanisms underlying such adverse cardiometabolic outcomes associated with sleep disorders in the health-sector shift workers.
文摘Objective To determine whether reduction in central pressure augmentation and central systolic blood pressure by nitroglycerine (NTG) results from effects on pre-load or is due to arterial dilation. Methods We compared effects of NTG with those of lower body negative pressure (LBNP). Hemodynamic measurements were made at rest,during LBNP (10,20 and 30 mmHg,each for 15 min) and after NTG (10,30 and 100 μg/min,each dose for 15 min) in ten healthy volunteers. Cardiac pre-load,stroke volume and cardiac output were assessed by echocardiography. Central pressure augmentation and central systolic pressure were obtained by radial tonometry using a transfer function. Results LBNP (20 mmHg) and NTG (30 μg/min) reduced pre-load (as measured by the peak velocity of the S wave in the superior vena cava) to a similar degree [by (26.8±3.8)% and (23.9±3.4)%,respectively]. Compared to LBNP,NTG reduced systemic vascular resistance [by (32.9±7.5)%,P<0.01],decreased peripheral and central pressure augmentation [by (20.8±3.4)% units and (12.9±2.9)% units,respectively,each P<0.01]. Conclusion These results suggest that a reduction in pre-load does not explain reduction in pressure augmentation and central systolic blood pressure by NTG and that these effects are mediated through arterial dilation.
文摘Background: The ankle/brachial pressure index (ABPI) has been shown to be a good marker of systemic atherosclerosis and a powerful predictor of cardiovascular morbidity and mortality. The objective of this study was to determine the importance of measuring ABPI in Saudi patients with coronary artery disease (CAD). METHODS: This is a hospital based cross-sectional study which was conducted on all Saudi patients who underwent coronary angiography without symptoms of peripheral arterial disease at King Fahd Hospital of the University, Al-Khobar Saudi Arabia. All patients underwent measurement of their ABPI. The study was carried out between December 2010 and November 2011. RESULTS: During the study period, two hundred and five patients were included. Fifty-nine (28.8%) patients were Group II (ABPI ≤ 0.90) and the rest was Group I (ABPI > 0.90). Significant correlation was also found between low ABPI and the extent of CAD (mean number of arteries involved in Group I was 1.78 ± 0.83 compared to 2.10 ± 0.736 in Group II p = 0.011). Nevertheless, the correlation between low ABPI, and the severity of presentation of CAD were also significant (Incidence of myocardial infarction with congestive heart failure was 0.5% in Group I compared to 12% in Group II p CONCLUSION: The ABPI is an important prognostic indicator for Saudi patients with CAD.
文摘Background: In new outpatients, blood pressure should be measured in both arms. A previous study reported that an inter-arm systolic blood pressure difference (ΔSBP) of ≥10 mm Hg is associated with an increased risk of mortality. Aim: The aim was to identify the associations with absolute values of ΔSBP (|ΔSBP|) ≥10 mm Hg. Subjects and Methods: This study included 2481 patients. Patients with a body mass index ≥25 kg/m<sup>2</sup> were defined as obese. The group of A was defined as following: ankle-brachial index (ABI) was <0.9 or ≥1.3. ΔSBP was expressed as right arm BP minus left arm BP. |ΔSBP| ≥10 mm Hg were analyzed using multivariate logistic analysis. Results: |ΔSBP| ≥10 mm Hg was found in 6.0% of patients and |ΔSBP| < 5 mm Hg in 80.4%. In multivariate analysis, the odds ratios (ORs) of the associations with |ΔSBP| ≥10 mm Hg were significantly associated with abnormal ABI and obesity regardless of sex and age. Moreover, the OR of the combined effects of abnormal ABI and obesity was higher than that of abnormal ABI and obesity alone. Conclusion: |ΔSBP| ≥10 mm Hg was associated with abnormal ABI and obesity. In a primary care setting, blood pressure should be actively measured in both arms. This study suggests that the associations with |ΔSBP| ≥10 mm Hg may be a useful part of screening for abnormal ABI.
文摘By analyzing hundreds of capillary pressure curves, the controlling factors of shape and type of capillary pressure curves are found and a novel method is presented to construct capillary pressure curves by using reservoir permeability and a synthesized index. The accuracy of this new method is verified by mercury-injection experiments. Considering the limited quantity of capillary pressure data, a new method is developed to extract the Swanson parameter from the NMR T2 distribution and estimate reservoir permeability. Integrating with NMR total porosity, reservoir capillary pressure curves can be constructed to evaluate reservoir pore structure in the intervals with NMR log data. An in-situ example of evaluating reservoir pore structure using the capillary pressure curves by this new method is presented. The result shows that it accurately detects the change in reservoir pore structure as a function of depth.
基金supported by the New Technique Project of Shengjing Hospital of China Medical University,China,No.2015-117(to XNY)
文摘The main goal of spinal cord rehabilitation is to restore walking ability and improve walking quality after spinal cord injury(SCI). The spatiotemporal parameters of walking and the parameters of plantar pressure can be obtained using a plantar pressure analysis system. Previous studies have reported step asymmetry in patients with bilateral SCI. However, the asymmetry of other parameters in patients with SCI has not been reported. This was a prospective, cross-sectional study, which included 23 patients with SCI, aged 48.1 ± 14.5 years, and 28 healthy subjects, aged 47.1 ± 9.8 years. All subjects underwent bare foot walking on a plantar pressure measurement device to measure walking speed and spatiotemporal parameters. Compared with healthy subjects, SCI patients had slower walking speed, longer stride time and stance time, larger stance phase percentage, and shorter stride length. The peak pressures under the metatarsal heads and toe were lower in SCI patients than in healthy subjects. In the heel, regional impulse and the contact area percentage in SCI patients were higher than those in healthy subjects. The symmetry indexes of stance time, step length, maximum force, impulse and contact area were increased in SCI patients, indicating a decline in symmetry. The results confirm that the gait quality, including spatiotemporal variables and plantar pressure parameters, and symmetry index were lower in SCI patients compared with healthy subjects. Plantar pressure parameters and symmetry index could be sensitive quantitative parameters to improve gait quality of SCI patients. The protocols were approved by the Clinical Research Ethics Committee of Shengjing Hospital of China Medical University(approval No. 2015 PS54 J) on August 13, 2015. This trial was registered in the ISRCTN Registry(ISRCTN42544587) on August 22, 2018. Protocol version: 1.0.
基金Supported by the National Natural Science Foundation of China(No.51305293)Tianjin Technical Innovation Funds for the Minor Sci-tech Enterprise(No.14C26211200362)
文摘This paper presents the evolution process of pressure angles from planar parallel mechanisms to spatial parallel mechanisms. Manipulability and condition number, which are frequently used in the optimum design of parallel mechanisms, are introduced from serial robots at first. Then, both theoretical analysis and practical experiences demonstrate that these concepts seem imperfect when they are used in parallel mechanisms. For this reason, this paper introduces the pressure angles in planar 4-bar mechanisms to spatial parallel mechanisms, which include redundant parallel mechanisms. Two kinds of pressure angles extracted from the determinant of direct and indirect Jacobian matrices are investigated. Moreover, two comprehensive and visible global performance indices are defined, showing the advantages in evaluating the workspace, singularity and motion/force transmission capabilities. With a 2-DOF planar and a 3-DOF spatial parallel mechanism as examples, the application of the performance indices is investigated and compared with the condition number at last. The proposed concept can be extended to other spatial parallel mechanisms.
基金Supported by Research project PRVOUK P37-08(from Charles University in Praha,Faculty of Medicine at Hradec Kralove,Czech Republic)
文摘To evaluate vital signs and body indices in Helicobacter pylori (H. pylori) positive and negative persons. A total of 22 centres entered the study. They were spread over the whole country, corresponding well to the geographical distribution of the Czech population. A total of 1818 subjects (aged 5-98 years) took part in the study, randomly selected out of 38147 subjects. H. pylori infection was investigated by means of a 13C-urea breath test. Data on height, weight, systolic and diastolic blood pressure and heart rate were collected at the clinics of general practitioners. The overall prevalence of H. pylori infection was 30.4% (402/1321) in adults (≥ 18 year-old) and 5.2% (26/497) in children and adolescents (≤ 17 year-old). Once adjusted for age and gender, only a difference in body mass index remained statistically significant with H. pylori positive adults showing an increase of 0.6 kg/m<sup>2</sup> in body mass index. Once adjusted for age and gender, we found a difference in height between H. pylori positive and H. pylori negative children and adolescents. On further adjustment for place of residence, this difference became statistically significant, with H. pylori positive children and adolescents being on average 3.5 cm shorter. H. pylori positive adults were significantly older compared to H. pylori negative subjects. Once adjusted for age and gender, H. pylori infection had no impact on body weight, body mass index and vital signs either in adults or children and adolescents. Chronic H. pylori infection appeared to be associated with short stature in children. H. pylori infection did not influence blood pressure, body weight and body mass index either in adults or children and adolescents.
基金supported by the National Natural Science Foundation of China(Grant No.51709132)the Natural Science Foundation of Jiangsu Province(Grant No.BK20150469)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(Grant No.KYCX18_2310)
文摘The paper focuses on Cassini oval pressure hulls under uniform external pressure. The Cassini oval pressure hull is proposed based on the shape index of Cassini oval. The buckling of a series of Cassini oval pressure hulls with the shape index of 0.09–0.30 and one spherical pressure hull with the diameter of 2 m is devoted. Such hulls are numerically studied in the case of constant volume, material properties, and wall thickness. The results show that Cassini oval pressure hulls with the shape index of 0.10–0.11 can resist about 4% more external pressure than the spherical one. This deviates from the classical mechanics conclusion that spherical shell is the optimal shape for underwater pressure resistant structures.
基金supported by the National High-Technology Research and Development Program of China (863 Program, 2013AA102900-3)
文摘Effects of continuous negative pressure water supply on water consumption, growth and development, as well as physiological mechanism and quality of Capsicum annuum L. were investigated in this paper. Meanwhile, the optimal negative pressure water supply conditions for growth of C. annuum L. were screened out to achieve the goals of water conservation, high yield and high quality, thus providing theoretical foundation for its field production. The pot experiment within the greenhouse was utilized; the continuous negative pressure water supply was adopted; the four treatments, artificial watering(CK), –5 k Pa(T1), –10 k Pa(T2), and –15 k Pa(T3) were set; and the daily water consumption, yield, as well as the biomass, nitrate reductase, root activity, vitamin C, capsaicin, and nutrient uptakes of nitrogen(N), phosphorus(P) and potassium(K) during various stages of its growth were determined. Compared with CK, when the water supply pressure was controlled at –5 to –15 k Pa in the experiment, the total water consumption of C. annuum L. reduced by 53.42 to 67.75%, the total water consumption intensity reduced by 54.29 to 67.14%, and the water use efficiency increased by 12.66 to 124.67%. The N accumulation in a single strain of C. annuum L. from the color turning stage to the red ripe stage increased by 15.99 to 100.55%, respectively, compared with that of CK; the P accumulation increased by 20.47 to 154.00% relative to that of CK, and the K accumulation increased by 64.92 to 144.9% compared with that of CK. Compared with CK, C. annuum L. yield was remarkably improved by 13.79% at T1, and contents of vitamin C, capsaicin as well as carotenoids at all growth stages were enhanced by 13.42–147.01%, 11.54–71.01%, and 41.1–568.06%, respectively. Nitrate reductase activity, root activity and chlorophyll(a+b) were markedly increased by 335.78–500%, 79.6–140.68% and 114.95–676.19%, respectively, from immature stage to full ripe stage. Adopting the continuous negative pressure water supply for C. annuum L. has a significant water-saving effect, and the water supply pressure being stable at –5 k Pa contributes to its growth and development, improves yield, enhances root activity, promotes nutrient uptake, and improves its quality, thus achieving the effects of water conservation, high yield, high quality and high efficiency.
基金supported by the Young Scholar Scientific Research Foundation of the Chinese Center for Disease Control and Prevention(grant#China CDC 2010A205)
文摘Objective To estimate the prevalence of elevated blood pressure(EBP) in Chinese children and identify individual and family factors associated with EBP. Methods A nationwide cross-sectional study was conducted in 2010 using stratified cluster sampling. Participants' blood pressure was measured, and their parents completed a questionnaire on personal and family characteristics. Prevalence and correlates of EBP were assessed. Results Among a total of 24,333 participants, 20.2% of boys and 16.3% of girls had EBP. The prevalence of EBP increased with the ascending trend of waist circumference, Waist-to-height ratio, and body mass index. The adjusted prevalence ratios(aP Rs) for obese boys and girls were 2.50 and 2.97, respectively. Fewer urban boys(16.2%) had EBP than rural boys(21.7%). Boys with a family history of hypertension were 12% more likely to have EBP. Children whose mothers received a college education tended to have lower likelihood of EBP; with an aP R was 0.85 among boys and 0.78 among girls. Conclusion EBP is common among obese students and those who have a family history of hypertension. A negative association between mothers' education levels and EBP risk in children was found.
文摘AIM:To evaluate the correlation between intraocular pressure(IOP)and various obesity-related health factors in patients with ocular hypertension in Korea.METHODS:A total of 40850 subjects underwent age,sex,body weight,and height assessments and automated multiphasic tests,including non-contact tonometry,automated perimetry,fundus photography,systolic/diastolic blood pressure measurement,and evaluation of obesity-related health parameters such as obesity index,body mass index(BMI),a body shape index(ABSI),and waist-to-height ratio(WtHR).Subjects were divided into ocular hypertension group and normal IOP group according to IOP after matching of age and sex.RESULTS:Of 40850 participants,1515(3.7%)had ocular hypertension,and 1515 with normal IOP were selected as controls using propensity score matching.The mean IOP of control group was 15.3±2.3 mm Hg,compared with 23.3±1.6 mm Hg in ocular hypertension group.Height,obesity index,BMI,and WtHR in the ocular hypertension group were significantly higher than in the normal IOP group(P<0.001,P<0.001,P=0.009,P=0.002).IOP of ocular hypertension was positively correlated with obesity index(P=0.027)and BMI(P=0.016),whereas IOP of control was positively correlated with blood pressure(P<0.001,P=0.002),obesity index(P<0.001),BMI(P<0.001),and WHtR(P=0.002).Systolic blood pressure(β=0.022,P<0.001)and body weight(β=0.016,P=0.02)were precursors of IOP in normal subjects,but sex(male;β=-0.231,P=0.008)and obesity index(β=-0.007,P=0.017)were precursors of ocular hypertension according to multiple regression analysis.CONCLUSION:Among various obesity-related health parameters,obesity index is the best indicator for further increase in IOP in ocular hypertension group.
文摘Rock typing is an important tool in evaluation and performance prediction of reservoirs.Different techniques such as flow zone indicator(FZI),FZI~*and Winland methods are used to categorize reservoir rocks into distinct rock types.Generally,these methods are applied to petrophysical data that are measured at a pressure other than reservoir pressure.Since the pressure changes the pore structure of rock,the effect of overburden pressure on rock typing should be considered.In this study,porosity and permeability of 113 core samples were measured at five different pressures.To investigate the effect of pressure on determination of rock types,FZI,FZI~*and Winland methods were applied.Results indicated that although most of the samples remain in the same rock type when pressure changes,some of them show different trends.These are related to the mineralogy and changes in pore system of the samples due to pressure change.Additionally,the number of rock types increases with increasing pressure.Furthermore,the effect of overburden pressure on determination of rock types is more clearly observed in the Winland and FZI~*methods.Also,results revealed that a more precise reservoir dynamic simulation can be obtained by considering the reservoir rock typing process at reservoir conditions.
基金Under the auspices of Education Ministry for Development of Liberal Arts and Social Science(No.14YJA790035)
文摘In this paper,we study the interactive relationship between the agglomeration of urban elements and the evolution of eco-environmental pressure.We build an index system for evaluating the agglomeration of urban elements and eco-environmental pressure.Using the entropy method and response intensity model,we analyze how urban elements agglomeration influenced eco-environmental pressure in Changchun from 1990 to 2012,eliciting the changing features and influential factors.Ultimately,we conclude there is a significant interactive relationship between the agglomeration of urban elements and the evolution of eco-environmental pressure in Changchun.This is inferred from the degree of this agglomeration in Changchun having increased since 1990,with the degree of eco-environmental pressure first decreasing and then increasing.Alongside this,the impact of urban elements agglomeration on eco-environmental pressure has changed from negative to positive.The main reasons behind this shift are arguably the rapid growth of urban investment and ongoing urbanization.
基金CSB!Project 95-04-02-01Natural Foundation of Shandong Province!Project Y97E02079fund of Laboratory of Tectonophysics, CS
文摘Results of triaxial compression experiment results show that granite rock strength increases with the depth until 30 km. In shallow crust, rock failure exhibits abrupt or quasi-abrupt instability under lower pressure. Acoustic Emission (AE for short) distributed almost uniformly before and after failure. Go through downwards into the depth range with progressive failure feature, there are no or only a few number of AE before and after failure. In deeper range, rock failure shows some feature of quasi-abrupt instability under high pressure. There are still few AE before failure, but with the stick-slip, much more An events were detected after failure. Under the temperature and pressure condition of more deep crust (about 26 km), rock failure takes abrupt instability under high pressure as main feature, there are dense AE activities before failure and cumulated frequency of AE increases exponentially before the failure. In about 35 km depth range, rock strength decreases quickly with the depth and sample exhibits semi-ductile or ductile progressive fails, there are no AE being detected before and after failure. The b value of AE sequence before failure seems a little smaller than that after failure, and b value roughly decreased with depth. The numerical range of index α is the widest in about 18 km depth and becomes narrow in the condition of more shallow or more deep crust. So, when the temperature and pressure condition simulating the real environment of focal depth changes from shallow to deep in the crust, the range of a of microfracture sequence would undergo such an evolvement process that a changes from narrow to wide and then to narrow again.
基金Supported by the Key Project of the National Eleventh-Five Year Research Program of China(2006BAJ05A08)the Open Fund of Jiang-su Key Laboratory of Resources and Environmental Information Engineering(20080301)the Science Fund(Youth) of China Univer-sity of Mining & Technology(2006A030)
文摘Based on the introduction of the general situation of research region,pressure index model of cultivated land is adopted according to the data of population,cultivated land area,crop sowing area,grain sowing area,and unit grain yield in the Statistical Yearbook of Fengxian County.The change of relevant factors of cultivated land pressure index over time is analyzed,as well as the tension level of cultivated land resources.Research shows that the pressure on cultivated land is relatively great in Fengxian County in the years 1999-2005.Grain supply and demand is still under the unsafe state.There will be more prominent contradiction between supply and demand of cultivated land in Fengxian County in the future,and the grain security will under greater pressure.Several countermeasures are put forward to ease the pressure on cultivated land in Fengxian County,in order to realize the sustainable use of cultivated land resources,to ensure the supply and demand balance of grain and cultivated land,and to stabilize and improve the grain productivity in Fengxian County,such as protecting the current cultivated land resources by the strictest protection system of cultivated land,enhancing the intensity of land development and reclamation,enlarging the area of cultivated land,increasing the agricultural sci-tech input,and improving the grain unit yield.
文摘Because of the paucity of serial blood pressure data on the same individuals, little is known about the accuracy of elevated blood pressure (BP) in childhood for predicting hypertension (HBP) later in life. The availability of long-term serial BP data from the Fels Longitudinal Study (FLS) presents the opportunity to link HBP in adulthood directly to BP measured decades earlier in the same individuals as children. We analyzed serial data from 965 men and 1114 women in the FLS. We used an autoregressive-moving average (1, 1) [ARMA (1, 1)] longitudinal model to predict adult HBP from childhood values. For 15-year-old boys with SBP 15 mmHg and 30 mmHg above the average SBP of 90 mmHg, the probabilities of having HBP at age 35 are 0.18 and 0.33, respectively. The corresponding probabilities for 15-year-old girls are only 0.04 and 0.08. This striking sex difference in risk of HBP at age 35 between 15-year-old boys and girls indicates that the risk of developing HBP in women is low regardless of their childhood blood pressure at any age from 2 to 17 years. Men are about 4.25 times more likely to have HBP at age 35 than women over a range of SBP of 90 - 140 mmHg at age 15. The ARMA (1, 1) model allows the identification of boys at risk for HBP as adult men.