PubMed Health⌕ Search

Biomedical subjects

Qiang Lin

Publications and source records attributed to Qiang Lin.

At least 19 recordsLinked to original sources
PubMed2006

An omnidirectional M-mode echocardiography system and its clinical application.

This paper introduces the omnidirectional M-mode echocardiography (OME), which can detect dynamic information from sequential echocardiography images. The method for detecting dynamic information is based on the rebuilding of their "gray (position)-time" function [Qiang L, Wenjing J, Li Z. A method for detecting dynamic information of sequential images--omnidirectional gray-time waveform and its applications in echocardiography images. In: Proceedings of CISST' 2001. 2001. p. 760-3; Qiang L, Wenjing J, Xiuzhi Y. A method for mining data of sequetial images-rebuilding of gray (position)-time function on arbitrary direction lines. In: Proceeding of CISST' 2002, vol. 3-6. 2002; Qiang L, Li Z, Wenjing J. The realization of omnidirectional gray-time waveform system and its application on echocardiography. J Electron Meas Instrum, 2002;16(1):70-5] on direction lines. The system can obtain motion and inherent dynamic information of a certain part of the cardiac structure at a certain moment. The system also shows a group of omnidirectional M-mode echocardiography images with synchronous ECG, which is rebuilt from 2D echocardiography images. The ECG supplies a standard time for the omnidirectional M-mode echocardiography images. The system has been applied in clinical application for 3 years and the results are good.

Algorithms↗
PubMed2006

Coincidence subwavelength fractional Fourier transform.

The coincidence subwavelength fractional Fourier transforms (FRTs) with entangled photon pairs and incoherent light radiation are introduced as an extension of the recently introduced coincidence FRT. Optical systems for implementing the coincidence subwavelength FRTs are designed. The width of the coincidence subwavelength FRT pattern is two times narrower than the width of the coincidence FRT. The coincidence subwavelength FRT with partially coherent light radiation is also studied numerically. Differences between the coincidence subwavelength FRT with entangled photon pairs and that with incoherent light radiation are discussed.

Journal Article↗
PubMed2006

[The influence of soybean isoflavone on expression of low density lipoprotein receptor (LDLR) mRNA in ovariectomied rats].

OBJECTIVE: To investigate the effect of soybean isoflavone on blood lipid and the expression of LDLR mRNA in ovariectomied rats. METHODS: Forty eight Sprague-Dawley rats were divided randomly into four groups: Sham group (sham), OVX group (OVX), OVX + gemifibrozil (G) group (OVX + G) and OVX + isoflavone (ISO) group (OVX_ISO). in which the rats were treated with G or ISO for three months starting from two weeks after both sides of rat' s ovarietomy. Blood sample were taken out for determination of blood lipid. The liver tissue were taken out quickly, Isothiocyanate guanidine-phenol-chloroform was used to extract the total RNA from the liver and RT-PCR was used to detect the expression of LDLR mRNA. RESULTS: Compared with the OVX group, contents of TG, LDL-C and OX-LDL in serum in OVX + ISO group decreased remarkably, and the contents of HDL-C increased. LDLR mRNA in OVX + ISO group increased distinctively compared with OVX group and OVX + G group. CONCLUSION: The level of mRNA of LDLR in liver decreas after ovariotormy and the soybean isoflavone may increase it by regulating the expression level of LDLR through transcription.

Animals↗
PubMed2005

Broadly tunable femtosecond parametric oscillator using a photonic crystal fiber.

Pulses as short as 460 fs and a tuning range as wide as 200 nm around 1 microm have been achieved from a photonic-crystal-fiber-based parametric oscillator. The ring cavity with only 65 cm of photonic crystal fiber is synchronously pumped with a tunable passively mode-locked Yb-doped fiber laser. Widely extended tunability is achieved by using the modulation instability gain in normal dispersion as the result of high-order dispersion in the photonic crystal fiber.

Journal Article↗
PubMed2005

[Correlation between prevalent and incident osteoporotic vertebral fractures in Beijing male elderly].

OBJECTIVE: To investigate the correlation between prevalent and incident osteoporotic vertebral fractures in Beijing male elderly. METHODS: Roentgenography of the thoracic and lumber vertebrae (T4-L4) and dual X-ray absorptiometry at the lumber spine (L2-4) and proximal femur (neck, greater trochanter, and Ward's triangle) were conducted so as to observe the vertebrae and measure the bone density upon 271 Beijing men, aged 72 +/- 6 (63.1 - 92.7). The subjects were followed up for 3.7 +/- 0.4 years. RESULTS: Prevalent fractures involving 98 vertebrae, mostly T12-L1 and mostly I degrees fracture, occurred in 71 men with an incidence rate of 28.3% (95% CI 22.8% - 34.3%). Incident fracture, mostly T12-L1 and mostly I degrees fracture too, occurred in 8 patients (95% CI 1.4% - 6.2%). The average baseline age of those with incident fracture was 77 +/- 8, significant higher than those of the subjects without fracture (71 +/- 6) and the subjects with only prevalent fractures (72 +/- 5) (both P < 0.05). The body height and weight of the subjects with only prevalent fractures were significantly lower than those of the other 2 groups (P = 0.025 and P = 0.05). However, the body mass index (BMI) was not significantly different among these 3 groups. The bone density values of femur neck and greater trochanter of the group with prevalent fracture but without incident fracture were 0.81 g/cm(2) +/- 0.11 and 0.4 g/cm(2) +/- 0.11 g/cm(2) respectively, both significantly lower than those of the group without fracture (0.85 g/cm(2) +/- 0.11 g/cm(2) and 0.78 g/cm(2) +/- 0.11 g/cm(2) respectively, both P < 0.05). The BMI value decreased in the order of the group without fracture, the group with only prevalent fracture, and the group with prevalent and incident fracture. The incidence rate of incident fracture was 7% in the group with prevalent fracture, significantly lower than that in the group without fracture (1.7%, P < 0.05). Among those with prevalent fracture the higher the degree of the prevalent fracture the more cases of incident fracture (P = 0.02). The incidence rate of incident fracture in those with prevalent fracture of 4 vertebrae was 33.3%, higher than those in other 2 groups. Logistic analysis showed that the baseline age and severity of vertebral fracture were closely correlated with incident fracture (OR = 1.229, 95% CI 1.037 - 1.407, and OR = 4.270, 95% CI 1.691 - 19.785). CONCLUSION: As independent of BMI, baseline age and severity of prevalent fracture are closely correlated with incident fracture in Beijing male elderly. Baseline BMI is a strong predictor of fracture risk.

Aged↗
PubMed2005

[Effect of age on the precision of dual X-ray absorptiometry measurement in middle-aged and elderly women].

OBJECTIVE: To investigate whether age influence the precision of dual X-ray absorptiometry (DXA) measurement at the hip in middle-aged and elderly women. METHODS: Totally 90 women were randomly selected and divided into three age groups: 45-55 years, 56-65 years, and 66-75 years. Each age group contained 30 women. Each woman was scanned twice at the same day. Bone mineral density (BMD) values of femoral neck, ward's triangle, and trochanter were collected and grouped by calculating the root mean square (RMS). Precision errors were expressed as RMS (standard deviation, SD). RESULTS: For the femoral neck and trochanter, significant differences of SD of BMD existed among all age groups. For the ward's triangle, significant difference of BMD existed among all age groups except between the 45-55 group and 56-65 age group. CONCLUSION: Age can influence the precision of DXA measurement at the hip in middle-aged and elderly women.

Absorptiometry, Photon↗
PubMed2005

Electro-acupuncture treatment for the upper segment ureterolithiasis under B-ultrasonography.

In order to explore the effects of the local strong stimulation generated by electro-acupuncture for treatment of the upper segment ureterolithiasis, a controlled study was carried out among the treatment group (electro-acupuncture with strong stimulation), the control group I (medication) and the control group II (conventional acupuncture). The results showed that the differences in the cure rate and the total effective rate between the treatment group and the two control groups were significant in statistical analysis (P<0.05 and P<0.01 respectively). This indicates that better therapeutic effects can be obtained by the local strong stimulation generated by electro-acupuncture for treatment of the upper segment ureterolithiasis.

Acupuncture Therapy↗
PubMed2005

[Initial radiographic manifestations in patients with SARS].

OBJECTIVE: To observe initial radiographic manifestations and evaluate its value for the diagnosis and differential diagnosis in patients with severe acute respiratory syndrome (SARS). METHODS: Initial chest radiographs of 79 patients, 15 to 69 years old (mean age 34.1 years, 40 men and 39 women), were retrospectively reviewed in the study. For all patients, average temperature was 38.8 degrees C and mean time from onset of the fever to the time of initial radiographs taken was 5.8 days. Location, abnormal distribution, appearance of lung abnormalities, effusion of pericadiaum and pleura, and lymphadenopathy were observed. Abnormal distribution and associated findings were compared. Differences of mean age, temperature, and the time were statistically analyzed between patients with and without abnormal findings. RESULTS: Initial chest radiographs were normal in 36 of 79 patients (45.5%). Abnormal radiographs in 43 patients (81.3%) showed exudative changes. No significant difference of mean age and day (form onset of the fever to the time of initial radiographs taken) was found between the patients with and without abnormal initial chest radiographs (P > 0.05). No lymphadenopathy, effusion of pericadiaum and pleura were found on the initial chest radiographs. CONCLUSIONS: The main abnormal radiographic appearance of lung in patients with SARS is exudative changes. SARS patients with normal initial chest radiographs are not uncommon and abnormal radiographic findings may appear to be late after onset of fever. Therefore, more attention should be paid in the clinical diagnosis of SARS.

Adolescent↗
PubMed2004

Partially coherent flat-topped beam and its propagation.

A partially coherent beam with flat-topped profile is proposed. The cross-spectral density of this beam can be expressed as a finite series of the cross-spectral density of partially coherent Gaussian-Schell-model beams with different parameters. Analytical propagation formulas for partially coherent flat-topped beams are derived through aligned and misaligned optical systems. The propagation property of partially coherent flat-topped beams in free space is illustrated numerically. The fractional Fourier transform of partially coherent fiat-topped beams is also studied. Our method provides a convenient way to describe partially coherent flat-topped beams and treat their propagation and transformation.

Journal Article↗
PubMed2004

Effects of polarization-mode dispersion on fiber-based parametric amplification and wavelength conversion.

We present a vector theory of four-wave mixing in optical fibers and use it to discuss the effect of polarization-mode dispersion (PMD) on the performance of parametric amplifiers and wavelength converters. We show that PMD distorts the gain spectrum and makes it less uniform than that expected in the absence of residual birefringence. PMD also induces large fluctuations in the amplified or wavelength-converted signal.

Journal Article↗
PubMed2004

Murine alanine aminotransferase: cDNA cloning, functional expression, and differential gene regulation in mouse fatty liver.

Alanine aminotransferase (ALT) is a widely used index of liver integrity or hepatocellular damage in clinics as well as a key enzyme in intermediatary metabolism. In this study, we have cloned the complementary DNAs of murine homologues of human alanine aminotransferase 1 and 2 (ALT1 and ALT2). The deduced peptides of murine ALT1 (mALT1) and ALT2 (mALT2) share 87% and 93% identity, respectively, with their human counterparts at the amino acid level. Murine ALT genes localize to separate chromosomes, with mALT1 gene (gpt1) on chromosome 15 and mALT2 gene (gpt2) on chromosome 8. The murine gpt1 and gpt2 differ in messenger RNA expression: gpt1 is mainly expressed in liver, bowel, and white adipose tissue and gpt2 is highly expressed in muscle, liver, and white adipose tissue. Expression of recombinant mALT1 and mALT2 proteins in Escherichia coli (E. coli) produced functional enzymes that catalyze alanine transamination. The potential diagnostic value of ALT isoenzymes in liver disease was evaluated in an obese animal model. In fatty livers of obese mice, ALT2 gene expression is induced 2-fold, but ALT1 remains the same. Furthermore, in fatty liver, total hepatic ALT activity is elevated significantly by 30% whereas aspartate aminotransferase (AST) activity remains unchanged. In conclusion, these results indicate that ALT2 may be responsible for the increased ALT activity in hepatic steatosis and provide evidence that an ALT isoenzyme-specific assay may have more diagnostic value than the total ALT activity assay currently in clinical use.

Alanine Transaminase↗
PubMed2004

Hollow elliptical Gaussian beam and its propagation through aligned and misaligned paraxial optical systems.

A new mathematical model called hollow elliptical Gaussian beam (HEGB) is proposed to describe a dark-hollow laser beam with noncircular symmetry in terms of a tensor method. The HEGB can be expressed as a superposition of a series of elliptical Hermite-Gaussian modes. By using the generalized diffraction integral formulas for light passing through paraxial optical systems, analytical propagation formulas for HEGBs passing through paraxial aligned and misaligned optical systems are obtained through vector integration. As examples of applications, evolution properties of the intensity distribution of HEGBs in free-space propagation were studied. Propagation properties of HEGBs through a misaligned thin lens were also studied. The HEGB provides a convenient way to describe elliptical dark-hollow laser beams and can be used conveniently to study the motion of atoms in a dark-hollow laser beam.

Journal Article↗
PubMed2003

Superluminal propagation of light pulses: A result of interference.

The propagation of pulses through dispersive media was investigated by solving Maxwell's equations without any approximation. We show that the superluminal propagation of pulses through anomalous dispersive media is a result of the interference of different frequency components composed of the pulse. The coherence of the pulse plays an important role for the superluminal propagation. With the decrease of the coherence of the pulse, the propagation changes from superluminal to subluminal. We have shown that the anomalous dispersion (the real part of the susceptibility) not the amplification (the imaginary part of the susceptibility) plays the essential role in the superluminal propagation. Although the superluminality always exists as long as the spectrum of the coherent pulse is within the anomalously dispersive region, both the energy propagation velocity and the frontal velocity never exceed the light speed in the vacuum. The output pulse through the medium is not the original pulse; instead it carries the information of the original pulse and the information of the prepared medium.

Journal Article↗
PubMed2003

Hollow Gaussian beams and their propagation properties.

A new mathematical model, described as hollow Gaussian beams (HGBs), is proposed to describe a dark hollow laser beam (DHB). The area of the dark region across the HGBs can easily be controlled by proper choice of the beam parameters. Based on the Collins integral, an analytical propagation formula for the HGBs through a paraxial optical system is derived. The HGBs also can be expressed as a superposition of a series of Lagurerre-Gaussian modes by use of a polynomial expansion. As a numerical example, the propagation properties of a DHB in free space are illustrated graphically. The HGBs provide a convenient and powerful way to describe and treat the propagation of DHBs and can be used conveniently to analyze atoms manipulated with a DHB.

Journal Article↗
PubMed2003

Propagation of partially coherent pulsed beams in the spatiotemporal domain.

A generalized model to describe the spatiotemporal partially coherent pulsed beams is presented. The corresponding propagation formula is derived by using the partially coherent light theory. Based on this formula, we obtain a nonstationary generalized ABCD law (which illustrates the transformation of optical beams or pulses passing through media) to describe the spatiotemporal behavior of partially coherent Gaussian pulsed beams. The physical meaning of such generalized pulsed beams is discussed. An example to illustrate the application of this law is given.

Journal Article↗
PubMed2003

Single-cycle electromagnetic pulses produced by oscillating electric dipoles.

We report an exact analytic solution of the Maxwell equations that is capable of describing single-cycle electromagnetic pulses beyond the slowly varying envelope approximation. The solution is based on the radiation field emitted by oscillating electric dipoles under the complex-source-point model. The spatiotemporal evolution of single-cycle electromagnetic pulses in free space is illustrated and discussed in detail by using the analytic solution obtained.

Journal Article↗
PubMed2003

Decentered elliptical Hermite-Gaussian beam.

A new kind of laser beam called the decentered elliptical Hermite-Gaussian beam (DEHGB) is defined by use of a tensor method. The propagation formula of the DEHGB passing through a nonsymmetrical paraxial optical system is derived through vector integration. The derived formula can be easily reduced to the propagation formula of an aligned elliptical Hermite-Gaussian beam and that of a decentered elliptical Gaussian beam under certain conditions. By use of this formula, the propagation characteristics of the DEHGB through free space are presented graphically. As application examples, we construct a generalized laser array using the DEHGB as the fundamental mode. We also obtain the decentered elliptical flattened Gaussian beam by expressing it as superposition of a series of DEHGBs by using polynomial expansion.

Journal Article↗