Background: Knowledge of temporal evolution of preeclampsia (PE) in its various aspects is essential in strategies to reduce maternal and perinatal morbidity and mortality. Preeclampsia is a public health problem due ...Background: Knowledge of temporal evolution of preeclampsia (PE) in its various aspects is essential in strategies to reduce maternal and perinatal morbidity and mortality. Preeclampsia is a public health problem due to maternal mortality associated with it worldwide (5.6%). Improving quality of its management is a major challenge in low-income countries where, despite progress made in this field, PE remains a major factor in maternal morbidity and mortality. Objective: To evaluate temporal evolution of frequency, risk factors and complications of PE at the University clinics of Kinshasa (UCK). Methods: Descriptive and cross-sectional study concerning minimum simple size of 119 pregnant women who consulted for antenatal care at the University clinics of Kinshasa from January 2012 to December 2022. Results will be reported as percentage proportion, mean and standard deviation. Comparison of proportion and means between groups will be made using Student’s t-test and Pearson’s chi-square test, respectively. The test will be statistically significant for a p value ≤ less than 0.05. Data will be collected and analysed anonymously and confidentially. Conclusion: This study will allow us to evaluate the effectiveness of different prevention and treatment modalities used over time in management of preeclampsia in our setting.展开更多
Introduction: Obstetric emergencies are clinical situations of a serious nature, often dangerous, which develop unexpectedly, threatening the vital prognosis of the mother and/or foetus in the short term. The aim of t...Introduction: Obstetric emergencies are clinical situations of a serious nature, often dangerous, which develop unexpectedly, threatening the vital prognosis of the mother and/or foetus in the short term. The aim of this study was to contribute to a review of obstetric emergencies at the Labé Regional Hospital maternity unit. Methods: This was a prospective descriptive and analytical study conducted over a period of 6 months in the maternity unit of the Labé Regional Hospital. It concerned all patients admitted to the department for obstetric emergencies. Results: Obstetric emergencies accounted for 20% of obstetric admissions. The mean age of the patients was 25.12 ± 7.15 years, with extremes of 14 and 45 years. The patients were housewives (42.52%), 42.86% did not attend school and 77.41% were from urban areas. The poor were the most numerous (43.52%). The ambulance was the means of transport in only 9% of cases. Acute foetal distress, pre-eclampsia, bony dystocia and post-partum haemorrhage were the most common types of emergency in our series, with frequencies of 27.57%, 22.59%, 17.94% and 10.63% respectively. The risk factors identified were age, origin, gestational age and the state of the maternal pelvis. Conclusion: Obstetric emergencies are frequent in our study site and represent a major concern for patients, providers and the community alike. In order to reduce the frequency of obstetric emergencies, young girls should be enrolled in school, the legal age for marriage should be respected, quality antenatal care should be provided in basic health facilities, and proper planning and spacing of pregnancies should be implemented.展开更多
Generation of single-sideband （SSB） multi-carrier source based on a recirculating frequency shifter （RFS） is anal- ysed theoretically and realized experimentally. The effects of affecting factors originating from ...Generation of single-sideband （SSB） multi-carrier source based on a recirculating frequency shifter （RFS） is anal- ysed theoretically and realized experimentally. The effects of affecting factors originating from the deviation from the right operation bias voltage and unbalanced amplitude, and the phase of the radio frequency （RF） drive signals on the performance of the multi-tone source are discussed in detail. Based on the theoretical analysis, high-quality 50-tone out- put is successfully realized. Experiments under some implementation imperfections are also carried out. The imperfect and low-quality output results are in good agreement with theoretical analysis.展开更多
In this work the influence of the density of the molten metal on the emergence of the raining phenomenon in the horizontal centrifugal casting process is numerically studied. Transient 2D numerical simulations were ca...In this work the influence of the density of the molten metal on the emergence of the raining phenomenon in the horizontal centrifugal casting process is numerically studied. Transient 2D numerical simulations were carried out using Computational Fluid Dynamics software. Three molten metals with different density, namely aluminum, iron and lead, and three angular frequencies, namely 50, 66 and 77 rad/s were considered. It is found that the density of the molten metal significantly affects the emergence, transient or permanent, of the rain phenomenon. However, the magnitude and duration of the rain phenomenon depend on the angular frequency of the rotating mold. Likewise, since gravitational forces affect the metal according to its density, the value of the critical rotation speed of the mold is also affected.展开更多
In mineral exploration, the apparent resistivity and apparent frequency （or apparent polarizability） parameters of induced polarization method are commonly utilized to describe the induced polarization anomaly. When...In mineral exploration, the apparent resistivity and apparent frequency （or apparent polarizability） parameters of induced polarization method are commonly utilized to describe the induced polarization anomaly. When the target geology structure is significantly complicated, these parameters would fail to reflect the nature of the anomaly source, and wrong conclusions may be obtained. A wavelet approach and a metal factor method were used to comprehensively interpret the induced polarization anomaly of complex geologic bodies in the Adi Bladia mine. Db5 wavelet basis was used to conduct two-scale decomposition and reconstruction, which effectively suppress the noise interference of greenschist facies regional metamorphism and magma intrusion, making energy concentrated and boundary problem unobservable. On the basis of that, the ore-induced anomaly was effectively extracted by the metal factor method.展开更多
Effects of pressure and temperature in the chamber during vacuum drying on the relative humidity and evaporation of wood surface were investigated by using the vacuum chamber. The setting temperature during vacuum dry...Effects of pressure and temperature in the chamber during vacuum drying on the relative humidity and evaporation of wood surface were investigated by using the vacuum chamber. The setting temperature during vacuum drying included dry-bulb temperature ta, the wet-bulb temperature tw and the temperature difference between the air in the vacuum chamber and the cooling water in the condenser. Results indicated that relative humidity during vacuum drying was affected by the dry-bulb temperature td, the wet-bulb temperature tw and the temperature difference between the air in the vacuum chamber and the water in the condenser. Relative humidity of wood decreased with the increase in temperature at the given temperature of the water in the condenser. The relative humidity was affected slightly by pressure in the vacuum chamber pA, and it decreased from 70% to 65% with pA increased from 50 kPa to 101 kPa. Moreover, there was nearly no evaporation under the vacuum without external heating.展开更多
分段估计法作为一种重要的非线性振型结构高频天平(high-frequency force balance,HFFB)试验模态力计算方法,可以对结构脉动风荷载的空间分布进行估计。该文章抛弃了分段估计法中无量纲风荷载谱沿高度不变的假定,提出了一种可以考虑荷...分段估计法作为一种重要的非线性振型结构高频天平(high-frequency force balance,HFFB)试验模态力计算方法,可以对结构脉动风荷载的空间分布进行估计。该文章抛弃了分段估计法中无量纲风荷载谱沿高度不变的假定,提出了一种可以考虑荷载谱沿高度变化的方法。以Kaimal脉动风谱为例提出并推导了无量纲风荷载谱沿高度变化的修正系数,并以某真型输电塔架为算例,结合HFFB试验,分析了修正系数对结构响应计算的影响。研究结果表明,修正前后位移响应的背景分量计算值差异很小,但共振分量差别明显,偏差幅度达25%。对柔度较大的高耸结构,其共振分量在总响应中占比较高,需考虑荷载谱沿高度的变化;对于沿高度减小或增大的风速谱而言,现有荷载谱沿高度不变的分段估计法将高估或低估结构的位移响应。本文方法具有更高精度和更广的适用性。展开更多
Nerve growth factor（NGF） plays an important role in promoting neuroregeneration after peripheral nerve injury. However, its effects are limited by its short half-life; it is therefore important to identify an effect...Nerve growth factor（NGF） plays an important role in promoting neuroregeneration after peripheral nerve injury. However, its effects are limited by its short half-life; it is therefore important to identify an effective mode of administration. High-frequency ultrasound（HFU） is increasingly used in the clinic for high-resolution visualization of tissues, and has been proposed as a method for identifying and evaluating peripheral nerve damage after injury. In addition, HFU is widely used for guiding needle placement when administering drugs to a specific site. We hypothesized that HFU guiding would optimize the neuroprotective effects of NGF on sciatic nerve injury in the rabbit. We performed behavioral, ultrasound, electrophysiological, histological, and immunohistochemical evaluation of HFU-guided NGF injections administered immediately after injury, or 14 days later, and compared this mode of administration with intramuscular NGF injections. Across all assessments, HFU-guided NGF injections gave consistently better outcomes than intramuscular NGF injections administered immediately or 14 days after injury, with immediate treatment also yielding better structural and functional results than when the treatment was delayed by 14 days. Our findings indicate that NGF should be administered as early as possible after peripheral nerve injury, and highlight the striking neuroprotective effects of HFU-guided NGF injections on peripheral nerve injury compared with intramuscular administration.展开更多
In this paper, three existing source spectral models for stochastic finite-fault modeling of ground motion were reviewed. These three models were used to calculate the far-field received energy at a site from a vertic...In this paper, three existing source spectral models for stochastic finite-fault modeling of ground motion were reviewed. These three models were used to calculate the far-field received energy at a site from a vertical fault and the mean spectral ratio over 15 stations of the Northridge earthquake, and then compared. From the comparison, a necessary measure was observed to maintain the far-field received energy independent of subfault size and avoid overestimation of the long- period spectra/level. Two improvements were made to one of the three models （i.e., the model based on dynamic comer frequency） as follows： （i） a new method to compute the subfault comer frequency was proposed, where the subfault comer frequency is determined based on a basic value calculated from the total seismic moment of the entire fault and an increment depending on the seismic moment assigned to the subfault; and （ii） the difference of the radiation energy from each suhfault was considered into the scaling factor. The improved model was also compared with the unimproved model through the far-field received energy and the mean spectral ratio. The comparison proves that the improved model allows the received energy to be more independent of subfault size than the unimproved model, and decreases the overestimation degree of the long-period spectral amplitude.展开更多
In order to contribute to the improvement of brain infarction management in Brazzaville, a cross-sectional and analytical study with prospective data collection was conducted in the cardiology and neurology department...In order to contribute to the improvement of brain infarction management in Brazzaville, a cross-sectional and analytical study with prospective data collection was conducted in the cardiology and neurology departments of the Brazzaville University Hospital, from February 1 to July 31, 2018. It included patients hospitalized for cerebral infarction confirmed with imaging, and having done an etiological assessment with at least one electrocardiogram at rest and one of long duration. Among these 138 patients included, 11 had atrial fibrillation, equaling?a frequency of 7.9%. The mean age of AF patients was 71 ± 8.8 years. The cardiovascular risk factors found were hypertension in eight cases (72.7%), diabetes in five cases (45.5%), abdominal obesity in four cases (36.4%). AF was permanent in 10 cases (91%), and paroxysmal in one case (9%). It was valvular in three cases (27.3%) and non-valvular in eight cases (72.7%). The cardiopathy involved was hypertensive in seven cases (63.6%), ischemic and valvular in two cases each. The CHA2DS2-VASc score, calculated in eight patients, was an average of 2.2, and ≥2 in more than 80% of patients;HAS-BLED score of 2.4 on average was ≥?3 in more than 72% of patients. Digoxin was prescribed in seven cases (63.6%) and an anti-vitamin K in eight cases (72.7%). In multivariate analysis, age (OR = 20.10, p = 0.023), arterial hypertension (OR = 23.82, p = 0.011), and dyslipidemia (OR = 2.03, p = 0.032) were the predictive factors found. AF is infrequent during brain infarction in Brazzaville. This systematic research raises the problem of age in our context.展开更多
Effects of pressure and temperature in the chamber during vacuum drying on the relative humidity and evaporation of wood surface were investigated by using the vacuum chamber.The setting temperature during vacuum dryi...Effects of pressure and temperature in the chamber during vacuum drying on the relative humidity and evaporation of wood surface were investigated by using the vacuum chamber.The setting temperature during vacuum drying included dry-bulb temperature td, the wet-bulb temperature tw and the temperature difference between the air in the vacuum chamber and the cooling water in the condenser.Results indicated that relative humidity during vacuum drying was affected by the dry-bulb temperature td, the wet-bulb temperature tw and the temperature difference between the air in the vacuum chamber and the water in the condenser.Relative humidity of wood decreased with the increase in temperature at the given temperature of the water in the condenser.The relative humidity was affected slightly by pressure in the vacuum chamber pA, and it decreased from 70% to 65% with pA increased from 50 kPa to 101 kPa.Moreover, there was nearly no evaporation under the vacuum without external heating.展开更多
The effect of the volume fraction of ferromagnetic metal （x） in （Ni75Fe25）x（ZnO）1-x nanogranular thin films on microstructural, soft-magnetic, and high-frequency properties was investigated. Good soft-magnetic p...The effect of the volume fraction of ferromagnetic metal （x） in （Ni75Fe25）x（ZnO）1-x nanogranular thin films on microstructural, soft-magnetic, and high-frequency properties was investigated. Good soft-magnetic properties were obtained in a broad x range, with 0.55 〈 x 〈 0.82. High resolution transmission electron microscopy （HRTEM） observations reveal that the grain size of the samples is lower than 14 nm, and that it decreases with decreasing x. Of special interest, our investigation of the permeability spectra indicates that these films exhibit an adjustable frequency linewidth of resonance peak, dependant upon changing x. Correspondingly, large and adjustable damping coefficients （aeff） from 0.023 to 0.043 were achieved by decreasing x from 0.82 to 0.55. Combined with the HRTEM results, the variation of αeff with x was analyzed in detail.展开更多
Background: Autonomic dysfunction in idiopathic Parkinson disease is a frequent and disabling complication, with an estimated prevalence of 47% and has a significant impact on the patient’s quality of life. Objective...Background: Autonomic dysfunction in idiopathic Parkinson disease is a frequent and disabling complication, with an estimated prevalence of 47% and has a significant impact on the patient’s quality of life. Objectives: The main objective of this study was to determine the frequency of autonomic dysfunction among Sudanese Parkinson patients and identify possible risk factors attribute to develop autonomic dysfunction and to assess the extent to which the progression of dysautonomia affects activities of daily living, health-related quality of life. Methods: In this descriptive perspective, cross-sectional hospital-based study, 51 patients were studied using standardized questionnaire including history and clinical examination. Results: A total of 51 patients have been examined: male to female ratio 1.5:1;mean age 55 ± 5 years;Parkinson disease duration, 7 ± 2 years. 47% of the patients had one or more symptoms of autonomic dysfunction with mean age 59 ± 10. Constipation and bloating were the most common symptoms where sweating abnormality was the least symptoms to observe. The symptom of autonomic dysfunction has been worse with disease progression in 50% of the patients and 47% of the patients reported that both motors and autonomic dysfunction symptoms were causing disability than autonomic dysfunction symptoms alone. Conclusions: The study demonstrates that autonomic dysfunction is not only common in Parkinson Disease, but it increases in severity with increasing disease stages. Older age with long disease duration was also considered along with advanced disease stages strong factors determining the presence of autonomic dysfunction. The study recommends that symptoms of autonomic dysfunction survey be a routine aspect of the evaluation of Parkinson disease patients, especially with advanced age.展开更多
<b><span>Background:</span></b><span> </span><span>Periodontitis is a multifactorial disease which is highly preva</span><span>lent worldwide. The control of ...<b><span>Background:</span></b><span> </span><span>Periodontitis is a multifactorial disease which is highly preva</span><span>lent worldwide. The control of periodontal risk factor network is of para</span><span>mount importance for the management of the disease.</span><span> </span><b><span>Aim:</span></b><b><span> </span></b><span>The aim of </span><span>this study was to assess the frequency and identify the factors associated wit</span><span>h periodontitis in Congolese patients.</span><span> </span><b><span>Material and Methods</span></b><b><span>:</span></b><span> </span><span>This cross-sectional study was carried out in four medical centers in the city of Kinshasa between April 2017 and April 2018. The study included patients aged at least 12 years old who consulted the dental services of these centers and who met the inclusion criteria. The participants underwent a structured interview and a clinical periodontal examination. The latter involved the entire dentition, and periodontal pocket and attachment level measurements were taken at six sites per tooth. The plaque and bleeding index were recorded. Logistic regression was used to identify associated factors. The significance level was set at p</span><span> < </span><span>0.05.</span><span> </span><b><span>Results</span></b><b><span>:</span></b><span> </span><span>The study included 827 patients and 42% of them had periodontitis. The most represented age group was between 20 and 29 years old. In multivariate analysis, age greater than or equal to 35 years, OR = 2.45 CI 95% (1.77</span><span> </span><span>-</span><span> </span><span>3.45), and the amount of plaque expressed as plaque index ≥</span><span> </span><span>1, OR = 2 CI </span><span>95% (1.31 </span><span>-</span><span> 3.07) were factors associated with periodontitis.</span><span> </span><b><span>Conclusion</span></b><b><span>:</span></b><span> </span><span>Factors associated with periodontitis found in this study are age ≥35 years and the amount of plaque expressed as plaque index ≥</span><span> </span><span>1. The latter reveals the importance of good oral hygiene.</span>展开更多
The characteristics of temporal and spatial distribution of tropical cyclone frequencies over the South China Sea areas and its affecting factors in the past 50yrs are analyzed based on typhoon data that provided by C...The characteristics of temporal and spatial distribution of tropical cyclone frequencies over the South China Sea areas and its affecting factors in the past 50yrs are analyzed based on typhoon data that provided by CMA and Simple Ocean Data Assimilation （SODA）. The results show that the tropical cyclone frequencies from June to October show concentrated geographic distribution, for they mainIy distribute over the SCS area from 15 - 20°N. The characteristics present significant interdecadal changes. The impact of oceanic factors on the tropical cyclone frequencies in the SCS area is mainly realized by La Nina and La Nifia-like events before 1975 but mainly by E1 Nino and E1 Nifio-like events after 1975.展开更多
Based on the Gauss linear frequency modulated wavelet transform, a new characteristic index is presented, namely time frequency energy attenuation factor which can reflect the difference features of waveform in earthq...Based on the Gauss linear frequency modulated wavelet transform, a new characteristic index is presented, namely time frequency energy attenuation factor which can reflect the difference features of waveform in earthquake focus mechanism, wave traveling path and its attenuation characteristics in focal area or near field. In order to test its validity, we select the natural earthquakes and explosion or collapse events whose focus mechanisms vary obviously,and some natural earthquakes located at the same site or in a very small area. The study indicates that the time frequency energy attenuation factors of the natural earthquakes are obviously different with that of explosion or collapse events, and the change of the time frequency energy attenuation factors is relatively stable for the earthquakes under the normal seismicity background. Using the above mentioned method, it is expected to offer a useful criterion for strong earthquake prediction by continuous earthquake observation.展开更多
Martens proposed a highly efficient and simply formed DFT algorithm——RCFA,whose efficien-cy is comparable with that of WFTA or that of PFA,and whose structure is similar to that of FFT.Theauthors have proved that,in...Martens proposed a highly efficient and simply formed DFT algorithm——RCFA,whose efficien-cy is comparable with that of WFTA or that of PFA,and whose structure is similar to that of FFT.Theauthors have proved that,in the case of radix 2,the RCFA is exactly equivalent to the twiddle factor mergedfrequency-decimal FFT algorithm.The twiddle factor merged time-decimal FFT algorithm is providedin this paper.Thus,in any case,the FFT algorithm used currently can be replaced by the more efficientalgorithm——the twiddle factor merged FFT algorithm,with exactly the same external property and thesimilar internal structure.Also in this paper,the software for implementing the twiddle factor merged FFTalgorithm(TMFFT)is provided.展开更多
In order to prevent and control environmental mass incidents,by comprehensively using literature research,case analysis and logical reasoning method,27 factors influencing environmental mass incidents were selected. A...In order to prevent and control environmental mass incidents,by comprehensively using literature research,case analysis and logical reasoning method,27 factors influencing environmental mass incidents were selected. Among them,15 key influencing factors were screened by Delphi-PCA-frequency analysis composite method. The key influencing factors were analyzed,and corresponding countermeasures were put forward.展开更多
The problem of soft-input so,output （ SISO ） detection for time-varying frequency-selec- tive fading channels is considered. Based on a suitably-designed factor graph and the sum-product al- gorithm, a low-complexit...The problem of soft-input so,output （ SISO ） detection for time-varying frequency-selec- tive fading channels is considered. Based on a suitably-designed factor graph and the sum-product al- gorithm, a low-complexity iterative message passing scheme is proposed for joint channel estima- tion, equalization and decoding. Two kinds of schedules （parallel and serial） are adopted in message updates to produce two algorithms with different latency. The computational complexity per iteration of the proposed algorithms grows only linearly with the channel length, which is a significantly de- crease compared to the optimal maximum a posteriori （MAP） detection with the exponential com- plexity. Computer simulations demonstrate the effectiveness of the proposed schemes in terms of bit error rate performance.展开更多
文摘Background: Knowledge of temporal evolution of preeclampsia (PE) in its various aspects is essential in strategies to reduce maternal and perinatal morbidity and mortality. Preeclampsia is a public health problem due to maternal mortality associated with it worldwide (5.6%). Improving quality of its management is a major challenge in low-income countries where, despite progress made in this field, PE remains a major factor in maternal morbidity and mortality. Objective: To evaluate temporal evolution of frequency, risk factors and complications of PE at the University clinics of Kinshasa (UCK). Methods: Descriptive and cross-sectional study concerning minimum simple size of 119 pregnant women who consulted for antenatal care at the University clinics of Kinshasa from January 2012 to December 2022. Results will be reported as percentage proportion, mean and standard deviation. Comparison of proportion and means between groups will be made using Student’s t-test and Pearson’s chi-square test, respectively. The test will be statistically significant for a p value ≤ less than 0.05. Data will be collected and analysed anonymously and confidentially. Conclusion: This study will allow us to evaluate the effectiveness of different prevention and treatment modalities used over time in management of preeclampsia in our setting.
文摘Introduction: Obstetric emergencies are clinical situations of a serious nature, often dangerous, which develop unexpectedly, threatening the vital prognosis of the mother and/or foetus in the short term. The aim of this study was to contribute to a review of obstetric emergencies at the Labé Regional Hospital maternity unit. Methods: This was a prospective descriptive and analytical study conducted over a period of 6 months in the maternity unit of the Labé Regional Hospital. It concerned all patients admitted to the department for obstetric emergencies. Results: Obstetric emergencies accounted for 20% of obstetric admissions. The mean age of the patients was 25.12 ± 7.15 years, with extremes of 14 and 45 years. The patients were housewives (42.52%), 42.86% did not attend school and 77.41% were from urban areas. The poor were the most numerous (43.52%). The ambulance was the means of transport in only 9% of cases. Acute foetal distress, pre-eclampsia, bony dystocia and post-partum haemorrhage were the most common types of emergency in our series, with frequencies of 27.57%, 22.59%, 17.94% and 10.63% respectively. The risk factors identified were age, origin, gestational age and the state of the maternal pelvis. Conclusion: Obstetric emergencies are frequent in our study site and represent a major concern for patients, providers and the community alike. In order to reduce the frequency of obstetric emergencies, young girls should be enrolled in school, the legal age for marriage should be respected, quality antenatal care should be provided in basic health facilities, and proper planning and spacing of pregnancies should be implemented.
基金Project supported by the National Natural Science Foundation of China (Grant No.60977049)the Chinese Universities Scientific Fund (Grant No.BUPT 2009RC0413)
文摘Generation of single-sideband （SSB） multi-carrier source based on a recirculating frequency shifter （RFS） is anal- ysed theoretically and realized experimentally. The effects of affecting factors originating from the deviation from the right operation bias voltage and unbalanced amplitude, and the phase of the radio frequency （RF） drive signals on the performance of the multi-tone source are discussed in detail. Based on the theoretical analysis, high-quality 50-tone out- put is successfully realized. Experiments under some implementation imperfections are also carried out. The imperfect and low-quality output results are in good agreement with theoretical analysis.
文摘In this work the influence of the density of the molten metal on the emergence of the raining phenomenon in the horizontal centrifugal casting process is numerically studied. Transient 2D numerical simulations were carried out using Computational Fluid Dynamics software. Three molten metals with different density, namely aluminum, iron and lead, and three angular frequencies, namely 50, 66 and 77 rad/s were considered. It is found that the density of the molten metal significantly affects the emergence, transient or permanent, of the rain phenomenon. However, the magnitude and duration of the rain phenomenon depend on the angular frequency of the rotating mold. Likewise, since gravitational forces affect the metal according to its density, the value of the critical rotation speed of the mold is also affected.
基金Project(41174103)supported by the National Natural Science Foundation of ChinaProject(2010-211)supported by the Foreign Mineral Resources Venture Exploration Special Fund of China
文摘In mineral exploration, the apparent resistivity and apparent frequency （or apparent polarizability） parameters of induced polarization method are commonly utilized to describe the induced polarization anomaly. When the target geology structure is significantly complicated, these parameters would fail to reflect the nature of the anomaly source, and wrong conclusions may be obtained. A wavelet approach and a metal factor method were used to comprehensively interpret the induced polarization anomaly of complex geologic bodies in the Adi Bladia mine. Db5 wavelet basis was used to conduct two-scale decomposition and reconstruction, which effectively suppress the noise interference of greenschist facies regional metamorphism and magma intrusion, making energy concentrated and boundary problem unobservable. On the basis of that, the ore-induced anomaly was effectively extracted by the metal factor method.
文摘Effects of pressure and temperature in the chamber during vacuum drying on the relative humidity and evaporation of wood surface were investigated by using the vacuum chamber. The setting temperature during vacuum drying included dry-bulb temperature ta, the wet-bulb temperature tw and the temperature difference between the air in the vacuum chamber and the cooling water in the condenser. Results indicated that relative humidity during vacuum drying was affected by the dry-bulb temperature td, the wet-bulb temperature tw and the temperature difference between the air in the vacuum chamber and the water in the condenser. Relative humidity of wood decreased with the increase in temperature at the given temperature of the water in the condenser. The relative humidity was affected slightly by pressure in the vacuum chamber pA, and it decreased from 70% to 65% with pA increased from 50 kPa to 101 kPa. Moreover, there was nearly no evaporation under the vacuum without external heating.
文摘分段估计法作为一种重要的非线性振型结构高频天平(high-frequency force balance,HFFB)试验模态力计算方法,可以对结构脉动风荷载的空间分布进行估计。该文章抛弃了分段估计法中无量纲风荷载谱沿高度不变的假定,提出了一种可以考虑荷载谱沿高度变化的方法。以Kaimal脉动风谱为例提出并推导了无量纲风荷载谱沿高度变化的修正系数,并以某真型输电塔架为算例,结合HFFB试验,分析了修正系数对结构响应计算的影响。研究结果表明,修正前后位移响应的背景分量计算值差异很小,但共振分量差别明显,偏差幅度达25%。对柔度较大的高耸结构,其共振分量在总响应中占比较高,需考虑荷载谱沿高度的变化;对于沿高度减小或增大的风速谱而言,现有荷载谱沿高度不变的分段估计法将高估或低估结构的位移响应。本文方法具有更高精度和更广的适用性。
基金supported by the National Natural Science Foundation of ChinaNo.81100922
文摘Nerve growth factor（NGF） plays an important role in promoting neuroregeneration after peripheral nerve injury. However, its effects are limited by its short half-life; it is therefore important to identify an effective mode of administration. High-frequency ultrasound（HFU） is increasingly used in the clinic for high-resolution visualization of tissues, and has been proposed as a method for identifying and evaluating peripheral nerve damage after injury. In addition, HFU is widely used for guiding needle placement when administering drugs to a specific site. We hypothesized that HFU guiding would optimize the neuroprotective effects of NGF on sciatic nerve injury in the rabbit. We performed behavioral, ultrasound, electrophysiological, histological, and immunohistochemical evaluation of HFU-guided NGF injections administered immediately after injury, or 14 days later, and compared this mode of administration with intramuscular NGF injections. Across all assessments, HFU-guided NGF injections gave consistently better outcomes than intramuscular NGF injections administered immediately or 14 days after injury, with immediate treatment also yielding better structural and functional results than when the treatment was delayed by 14 days. Our findings indicate that NGF should be administered as early as possible after peripheral nerve injury, and highlight the striking neuroprotective effects of HFU-guided NGF injections on peripheral nerve injury compared with intramuscular administration.
基金National Natural Science Foundation of China Under Grant No. 50778058 and 90715038National Key Technology R&D Program Under Contract No. 2006BAC13B02
文摘In this paper, three existing source spectral models for stochastic finite-fault modeling of ground motion were reviewed. These three models were used to calculate the far-field received energy at a site from a vertical fault and the mean spectral ratio over 15 stations of the Northridge earthquake, and then compared. From the comparison, a necessary measure was observed to maintain the far-field received energy independent of subfault size and avoid overestimation of the long- period spectra/level. Two improvements were made to one of the three models （i.e., the model based on dynamic comer frequency） as follows： （i） a new method to compute the subfault comer frequency was proposed, where the subfault comer frequency is determined based on a basic value calculated from the total seismic moment of the entire fault and an increment depending on the seismic moment assigned to the subfault; and （ii） the difference of the radiation energy from each suhfault was considered into the scaling factor. The improved model was also compared with the unimproved model through the far-field received energy and the mean spectral ratio. The comparison proves that the improved model allows the received energy to be more independent of subfault size than the unimproved model, and decreases the overestimation degree of the long-period spectral amplitude.
文摘In order to contribute to the improvement of brain infarction management in Brazzaville, a cross-sectional and analytical study with prospective data collection was conducted in the cardiology and neurology departments of the Brazzaville University Hospital, from February 1 to July 31, 2018. It included patients hospitalized for cerebral infarction confirmed with imaging, and having done an etiological assessment with at least one electrocardiogram at rest and one of long duration. Among these 138 patients included, 11 had atrial fibrillation, equaling?a frequency of 7.9%. The mean age of AF patients was 71 ± 8.8 years. The cardiovascular risk factors found were hypertension in eight cases (72.7%), diabetes in five cases (45.5%), abdominal obesity in four cases (36.4%). AF was permanent in 10 cases (91%), and paroxysmal in one case (9%). It was valvular in three cases (27.3%) and non-valvular in eight cases (72.7%). The cardiopathy involved was hypertensive in seven cases (63.6%), ischemic and valvular in two cases each. The CHA2DS2-VASc score, calculated in eight patients, was an average of 2.2, and ≥2 in more than 80% of patients;HAS-BLED score of 2.4 on average was ≥?3 in more than 72% of patients. Digoxin was prescribed in seven cases (63.6%) and an anti-vitamin K in eight cases (72.7%). In multivariate analysis, age (OR = 20.10, p = 0.023), arterial hypertension (OR = 23.82, p = 0.011), and dyslipidemia (OR = 2.03, p = 0.032) were the predictive factors found. AF is infrequent during brain infarction in Brazzaville. This systematic research raises the problem of age in our context.
基金supported by National Natural Science Foundation of China (No.30571453)Heilongjiang Postdoc-toral Science-Research Foundation (No. LBH-Q06116).
文摘Effects of pressure and temperature in the chamber during vacuum drying on the relative humidity and evaporation of wood surface were investigated by using the vacuum chamber.The setting temperature during vacuum drying included dry-bulb temperature td, the wet-bulb temperature tw and the temperature difference between the air in the vacuum chamber and the cooling water in the condenser.Results indicated that relative humidity during vacuum drying was affected by the dry-bulb temperature td, the wet-bulb temperature tw and the temperature difference between the air in the vacuum chamber and the water in the condenser.Relative humidity of wood decreased with the increase in temperature at the given temperature of the water in the condenser.The relative humidity was affected slightly by pressure in the vacuum chamber pA, and it decreased from 70% to 65% with pA increased from 50 kPa to 101 kPa.Moreover, there was nearly no evaporation under the vacuum without external heating.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.50901050 and 51101079)
文摘The effect of the volume fraction of ferromagnetic metal （x） in （Ni75Fe25）x（ZnO）1-x nanogranular thin films on microstructural, soft-magnetic, and high-frequency properties was investigated. Good soft-magnetic properties were obtained in a broad x range, with 0.55 〈 x 〈 0.82. High resolution transmission electron microscopy （HRTEM） observations reveal that the grain size of the samples is lower than 14 nm, and that it decreases with decreasing x. Of special interest, our investigation of the permeability spectra indicates that these films exhibit an adjustable frequency linewidth of resonance peak, dependant upon changing x. Correspondingly, large and adjustable damping coefficients （aeff） from 0.023 to 0.043 were achieved by decreasing x from 0.82 to 0.55. Combined with the HRTEM results, the variation of αeff with x was analyzed in detail.
文摘Background: Autonomic dysfunction in idiopathic Parkinson disease is a frequent and disabling complication, with an estimated prevalence of 47% and has a significant impact on the patient’s quality of life. Objectives: The main objective of this study was to determine the frequency of autonomic dysfunction among Sudanese Parkinson patients and identify possible risk factors attribute to develop autonomic dysfunction and to assess the extent to which the progression of dysautonomia affects activities of daily living, health-related quality of life. Methods: In this descriptive perspective, cross-sectional hospital-based study, 51 patients were studied using standardized questionnaire including history and clinical examination. Results: A total of 51 patients have been examined: male to female ratio 1.5:1;mean age 55 ± 5 years;Parkinson disease duration, 7 ± 2 years. 47% of the patients had one or more symptoms of autonomic dysfunction with mean age 59 ± 10. Constipation and bloating were the most common symptoms where sweating abnormality was the least symptoms to observe. The symptom of autonomic dysfunction has been worse with disease progression in 50% of the patients and 47% of the patients reported that both motors and autonomic dysfunction symptoms were causing disability than autonomic dysfunction symptoms alone. Conclusions: The study demonstrates that autonomic dysfunction is not only common in Parkinson Disease, but it increases in severity with increasing disease stages. Older age with long disease duration was also considered along with advanced disease stages strong factors determining the presence of autonomic dysfunction. The study recommends that symptoms of autonomic dysfunction survey be a routine aspect of the evaluation of Parkinson disease patients, especially with advanced age.
文摘<b><span>Background:</span></b><span> </span><span>Periodontitis is a multifactorial disease which is highly preva</span><span>lent worldwide. The control of periodontal risk factor network is of para</span><span>mount importance for the management of the disease.</span><span> </span><b><span>Aim:</span></b><b><span> </span></b><span>The aim of </span><span>this study was to assess the frequency and identify the factors associated wit</span><span>h periodontitis in Congolese patients.</span><span> </span><b><span>Material and Methods</span></b><b><span>:</span></b><span> </span><span>This cross-sectional study was carried out in four medical centers in the city of Kinshasa between April 2017 and April 2018. The study included patients aged at least 12 years old who consulted the dental services of these centers and who met the inclusion criteria. The participants underwent a structured interview and a clinical periodontal examination. The latter involved the entire dentition, and periodontal pocket and attachment level measurements were taken at six sites per tooth. The plaque and bleeding index were recorded. Logistic regression was used to identify associated factors. The significance level was set at p</span><span> < </span><span>0.05.</span><span> </span><b><span>Results</span></b><b><span>:</span></b><span> </span><span>The study included 827 patients and 42% of them had periodontitis. The most represented age group was between 20 and 29 years old. In multivariate analysis, age greater than or equal to 35 years, OR = 2.45 CI 95% (1.77</span><span> </span><span>-</span><span> </span><span>3.45), and the amount of plaque expressed as plaque index ≥</span><span> </span><span>1, OR = 2 CI </span><span>95% (1.31 </span><span>-</span><span> 3.07) were factors associated with periodontitis.</span><span> </span><b><span>Conclusion</span></b><b><span>:</span></b><span> </span><span>Factors associated with periodontitis found in this study are age ≥35 years and the amount of plaque expressed as plaque index ≥</span><span> </span><span>1. The latter reveals the importance of good oral hygiene.</span>
基金Research on Techniques of Predicting the Prospects of Drought and Flood Years inGuangdong – a project of the Science and Technology Plan of Guangdong Province (2005B32601007)Experiments with the Coupling between Typhoons, Waves and Storm Surges and Pre-estimation of Typhoon-inflicted Dagames, a project of the Research Fund for Tropical Oceanic and Meteorological Science
文摘The characteristics of temporal and spatial distribution of tropical cyclone frequencies over the South China Sea areas and its affecting factors in the past 50yrs are analyzed based on typhoon data that provided by CMA and Simple Ocean Data Assimilation （SODA）. The results show that the tropical cyclone frequencies from June to October show concentrated geographic distribution, for they mainIy distribute over the SCS area from 15 - 20°N. The characteristics present significant interdecadal changes. The impact of oceanic factors on the tropical cyclone frequencies in the SCS area is mainly realized by La Nina and La Nifia-like events before 1975 but mainly by E1 Nino and E1 Nifio-like events after 1975.
文摘Based on the Gauss linear frequency modulated wavelet transform, a new characteristic index is presented, namely time frequency energy attenuation factor which can reflect the difference features of waveform in earthquake focus mechanism, wave traveling path and its attenuation characteristics in focal area or near field. In order to test its validity, we select the natural earthquakes and explosion or collapse events whose focus mechanisms vary obviously,and some natural earthquakes located at the same site or in a very small area. The study indicates that the time frequency energy attenuation factors of the natural earthquakes are obviously different with that of explosion or collapse events, and the change of the time frequency energy attenuation factors is relatively stable for the earthquakes under the normal seismicity background. Using the above mentioned method, it is expected to offer a useful criterion for strong earthquake prediction by continuous earthquake observation.
文摘Martens proposed a highly efficient and simply formed DFT algorithm——RCFA,whose efficien-cy is comparable with that of WFTA or that of PFA,and whose structure is similar to that of FFT.Theauthors have proved that,in the case of radix 2,the RCFA is exactly equivalent to the twiddle factor mergedfrequency-decimal FFT algorithm.The twiddle factor merged time-decimal FFT algorithm is providedin this paper.Thus,in any case,the FFT algorithm used currently can be replaced by the more efficientalgorithm——the twiddle factor merged FFT algorithm,with exactly the same external property and thesimilar internal structure.Also in this paper,the software for implementing the twiddle factor merged FFTalgorithm(TMFFT)is provided.
基金Supported by the National Natural Science Foundation of China(41001338)Key Projects of Henan Colleges and Universities(15A610012)
文摘In order to prevent and control environmental mass incidents,by comprehensively using literature research,case analysis and logical reasoning method,27 factors influencing environmental mass incidents were selected. Among them,15 key influencing factors were screened by Delphi-PCA-frequency analysis composite method. The key influencing factors were analyzed,and corresponding countermeasures were put forward.
基金Supported by the National Natural Science Foundation of China(61201181)Specialized Research Fund for the Doctoral Program of Higher Education(20121101120020)the Co-innovation Laboratory of Aerospace Broadband Network Technology
文摘The problem of soft-input so,output （ SISO ） detection for time-varying frequency-selec- tive fading channels is considered. Based on a suitably-designed factor graph and the sum-product al- gorithm, a low-complexity iterative message passing scheme is proposed for joint channel estima- tion, equalization and decoding. Two kinds of schedules （parallel and serial） are adopted in message updates to produce two algorithms with different latency. The computational complexity per iteration of the proposed algorithms grows only linearly with the channel length, which is a significantly de- crease compared to the optimal maximum a posteriori （MAP） detection with the exponential com- plexity. Computer simulations demonstrate the effectiveness of the proposed schemes in terms of bit error rate performance.
