Rovibrational Energies of 13C16O2 Determined with Kilohertz Accuracy

Accurate spectroscopic data of carbon dioxide are widely used in many important applications, such as carbon monitoring missions. Here, we present comb-locked cavity ring-down saturation spectroscopy of the second most abundant isotopologue of CO2, 13C16O2. We determined the positions of 88 lines in three vibrational bands in the 1.6 μm region, 30011e/30012e/30013e-00001e, with an accuracy of a few kHz. Based on the analysis of combination differences, we obtained for the first time the ground-state rotational energies with kHz accuracy. We also provide a set of hybrid line positions for 150 13C16O2 transitions. The rotational energies (J < 50) in the 30013e vibrational state can be fitted by a set of rotational and centrifugal constants with deviations within a few kHz, indicating that the 30013e state is free of perturbations. These precise isotopic line positions will be utilized to improve the Hamiltonian model and quantitative remote sensing of carbon dioxide. Moreover, they will help to track changes in the carbon source and sink through isotopic analysis.

Monitoring Eye Movement in Patients with Parkinson's Disease: What Can It Tell Us?

Parkinson's disease (PD) affects approximately 10 million individuals worldwide. Visual impairments are a common feature of PD. Patients report difficulties with visual scanning, impaired depth perception and spatial navigation, and blurry and double vision. Examination of PD patients reveals abnormal fixational saccades, strabismus, impaired convergence, and abnormal visually-guided saccades. This review aims to describe objective features of abnormal eye movements in PD and to discuss the structures and pathways through which these abnormalities may manifest.

Fano-like Resonance due to Interference with Distant Transitions

Narrow optical resonances of atoms or molecules have immense significance in various precision measurements, such as testing fundamental physics and the generation of primary frequency standards. In these studies, accurate transition centers derived from fitting the measured spectra are demanded, which critically rely on the knowledge of spectral line profiles. Here, we propose a new mechanism of Fano-like resonance induced by distant discrete levels and experimentally verify it with Doppler-free spectroscopy of vibration-rotational transitions of CO_{2}. The observed spectrum has an asymmetric profile and its amplitude increases quadratically with the probe laser power. Our results facilitate a broad range of topics based on narrow transitions.

Comb-locked cavity-assisted double-resonance molecular spectroscopy based on diode lasers

Interactions between a molecule and two or more laser fields are of great interest in various studies, but weak and highly overlapping transitions hinder precision measurements. We present the method of comb-locked cavity-assisted double resonance spectroscopy based on narrow-linewidth continuous-wave lasers, which allows for state-selective pumping and probing of molecules. By locking two near-infrared diode lasers to one cavity with a finesse at the order of 10⁵, we measured all three types of double resonances. Carbon monoxide molecules with selected speeds along the laser beam were excited to vibrationally excited states, and absorption spectra with sub-MHz linewidths were observed. Positions of double resonance transitions were determined with an accuracy of 3.7 kHz, which was verified by comparing to Lamb-dip measurements. The present work paves the way to the pump-probe study of highly excited molecules with unprecedented precision.

Cavity ring-down spectroscopy based on a comb-locked optical parametric oscillator source

Spectroscopy of molecules in the mid-infrared (MIR) region has important applications in various fields, such as astronomical observation, environmental detection, and fundamental physics. However, compared to that in the near-infrared, precision spectroscopy in the MIR is often limited by the light source and has not shown full potential in sensitivity. Here we report a cavity ring-down spectroscopy system using a tunable narrow-linewidth optical parametric oscillator, which fulfills the requirement of high sensitivity and high precision in the MIR region. The Lamb-dip spectrum of the N₂O molecule at 2.7 μm was measured as a demonstration of spectroscopy in the MIR with kilohertz accuracy.

Dispersion-like lineshape observed in cavity-enhanced saturation spectroscopy of HD at 1.4 µm

Precision measurement of ro-vibrational transitions in the electronic ground state of the hydrogen molecule can be used to test quantum electrodynamics and also to determine the dimensionless proton-to-electron mass ratio. Saturation spectroscopy of the 2-0 overtone transitions of hydrogen deuterium (HD) were measured with three cavity-enhanced spectroscopy methods. With a sensitivity at the 10^-13cm^-1 level, we revealed a dispersion-like lineshape instead of a conventional Lamb "dip," which explains the significant discrepancy among previous independent measurements. The spectra can be fit well by using the Fano profile. Centers of R(1) and R(3) lines were determined as 217 105 182 111 (19)_stat(240)_syskHz and 220 704 305 234 (20)_stat(240)_syskHz, respectively.

[Clinical characteristics and gene expression profiles in children with ETV6-RUNX1 acute lymphoblastic leukemia]

目的

通过基因表达谱研究儿童ETV6-RUNX1阳性急性淋巴细胞白血病（ALL）异质性，探索不同聚类分组临床特征，为临床个性化诊疗及利用测序技术探索预后相对不良组预测模型提供可行性参考。

方法

应用改进的基因片段分析技术对2016年8月至2019年6月北京儿童医院收治的264例初诊ALL患儿的骨髓标本进行57个分型基因检测和聚类分析，重点分析56例ETV6-RUNX1阳性患者的基因表达谱与临床特点、免疫表型和早期化疗反应的关系。

结果

基因分型聚类显示ETV6-RUNX1阳性ALL被分为两组：E/R-1组（45例，80.4%）和E/R-2组（11例，19.6%）。E/R-2聚类离散度大于E/R-1，spearman相关系数分别为0.788、0.901；E/R-2、E/R-1组初诊PLT中位数分别为104（27～644）×10⁹/L、50（8～390）×10⁹/L（P<0.01），初诊骨髓原始幼稚细胞比例分别为0.830（0.270～0.975）、0.935（0.445～0.990）（P<0.05）；CD22⁺CD34⁺CD20⁻CD117⁻CD56⁻免疫组合在E/R-2组占比更高（P<0.001）；E/R-2和E/R-1组化疗第33天流式细胞术检测的微小残留病（MRD）转阴例数分别为5例（55.6%）和32例（88.9%）（P＝0.064），去除临界值病例敏感性分析转阴例数分别为5例（55.6%）和32例（91.4%）（P＝0.035）；第33天PCR检测的MRD转阴例数分别为7例（77.8%）和36例（100.0%）（P＝0.047）。

结论

ETV6-RUNX1阳性ALL患儿在基因表达谱层面存在异质性，符合E/R-2表达特征的患儿可能初诊时血小板减少倾向小但早期化疗反应相对不良。

Evidence-based umbrella review of 162 peripheral biomarkers for major mental disorders

The literature on non-genetic peripheral biomarkers for major mental disorders is broad, with conflicting results. An umbrella review of meta-analyses of non-genetic peripheral biomarkers for Alzheimer's disease, autism spectrum disorder, bipolar disorder (BD), major depressive disorder, and schizophrenia, including first-episode psychosis. We included meta-analyses that compared alterations in peripheral biomarkers between participants with mental disorders to controls (i.e., between-group meta-analyses) and that assessed biomarkers after treatment (i.e., within-group meta-analyses). Evidence for association was hierarchically graded using a priori defined criteria against several biases. The Assessment of Multiple Systematic Reviews (AMSTAR) instrument was used to investigate study quality. 1161 references were screened. 110 met inclusion criteria, relating to 359 meta-analytic estimates and 733,316 measurements, on 162 different biomarkers. Only two estimates met a priori defined criteria for convincing evidence (elevated awakening cortisol levels in euthymic BD participants relative to controls and decreased pyridoxal levels in participants with schizophrenia relative to controls). Of 42 estimates which met criteria for highly suggestive evidence only five biomarker aberrations occurred in more than one disorder. Only 15 meta-analyses had a power >0.8 to detect a small effect size, and most (81.9%) meta-analyses had high heterogeneity. Although some associations met criteria for either convincing or highly suggestive evidence, overall the vast literature of peripheral biomarkers for major mental disorders is affected by bias and is underpowered. No convincing evidence supported the existence of a trans-diagnostic biomarker. Adequately powered and methodologically sound future large collaborative studies are warranted.

Seeded optical parametric oscillator light source for precision spectroscopy

Precision spectroscopy of fundamental bands of molecules in the mid-infrared (MIR) region is of great interest in applications of trace detection and testing fundamental physics, where high-power and narrow-linewidth MIR lasers are needed. By using a frequency-stabilized near-infrared laser as a seed of the signal light of a continuous-wave optical parametric oscillator, we established a broadly tunable MIR light source that has an output power of several hundred milliwatts and a linewidth of a few tens of kilohertz. The MIR laser frequency drift was reduced to below 1 kHz by using an optical frequency comb to stabilize the frequency of the 1064 nm pumping laser. The performance of the light source was investigated and tested by measuring the saturated absorption spectroscopy of a few molecular transitions at 3.3 µm.

Comb-locked cavity ring-down spectroscopy with variable temperature

Temperature dependence of molecular absorption line shape is important information for spectroscopic studies and applications. In this work, we report a comb-locked cavity ring-down spectrometer employing a cryogenic cooler to perform absorption spectroscopy measurements at temperatures between 40 K and 300 K. As a demonstration, we recorded the spectrum of the R(0) line in the (2-0) band of HD at 46 K. The temperature was also confirmed by the Doppler width of the HD line. Spectra of CH₄ near 1.394 μm were also recorded in a wide temperature range of 70-300 K. Lower-state energies of methane lines were analyzed by fitting these spectra, which can be directly compared with the HITRAN and TheoReTS databases. Considerable deviations were observed, indicating the need to investigate the assignments of the methane lines in this region.

Interleukin-8 as a therapeutic target for chronic low back pain: Upregulation in human cerebrospinal fluid and pre-clinical validation with chronic reparixin in the SPARC-null mouse model

Background

Low back pain (LBP) is the leading global cause of disability and is associated with intervertebral disc degeneration (DD) in some individuals. However, many adults have DD without LBP. Understanding why DD is painful in some and not others may unmask novel therapies for chronic LBP. The objectives of this study were to a) identify factors in human cerebrospinal fluid (CSF) associated with chronic LBP and b) examine their therapeutic utility in a proof-of-concept pre-clinical study.

Methods

Pain-free human subjects without DD, pain-free human subjects with DD, and patients with chronic LBP linked to DD were recruited and lumbar MRIs, pain and disability levels were obtained. CSF was collected and analyzed by multiplex cytokine assay. Interleukin-8 (IL-8) expression was confirmed by ELISA in CSF and in intervertebral discs.

The SPARC-null mouse model of progressive, age-dependent DD and chronic LBP was used for pre-clinical validation. Male SPARC-null and control mice received systemic Reparixin, a CXCR1/2 (receptors for IL-8 and murine analogues) inhibitor, for 8 weeks. Behavioral signs of axial discomfort and radiating pain were assessed. Following completion of the study, discs were excised and cultured, and conditioned media was evaluated with a protein array.

Findings

IL-8 was elevated in CSF of chronic LBP patients with DD compared to pain-free subjects with or without DD. Chronic inhibition with reparixin alleviated low back pain behaviors and attenuated disc inflammation in SPARC-null mice.

Interpretation

These studies suggest that the IL-8 signaling pathway is a viable therapy for chronic LBP.

Fund

Supported by NIH, MMF, CIHR and FRQS.

Frequency metrology of molecules in the near-infrared by NICE-OHMS

Noise-immune cavity enhanced optical heterodyne molecular spectroscopy (NICE-OHMS) is extremely sensitive in detecting weak absorption. However, the use of NICE-OHMS for metrology study was also hindered by its sensitivity to influence from various experimental conditions such as the residual amplitude modulation. Here we demonstrate to use NICE-OHMS for precision measurements of Lamb-dip spectra of molecules. After a dedicated investigation of the systematic uncertainties in the NICE-OHMS measurement, the transition frequency of a ro-vibrational line of C₂H₂ near 789 nm was determined to be 379 639 280 915.3±1.2 kHz (fractional uncertainty 3.2 × 10^-12), agreeing well with, but more accurate than, the value determined from previous cavity ring-down spectroscopy measurements. The study indicates the possibility to implement the very sensitive NICE-OHMS method for frequency metrology of molecules, or a molecular clock, in the near-infrared.

Toward a Determination of the Proton-Electron Mass Ratio from the Lamb-Dip Measurement of HD

Precision spectroscopy of the hydrogen molecule is a test ground of quantum electrodynamics (QED), and it may serve for the determination of fundamental constants. Using a comb-locked cavity ring-down spectrometer, for the first time, we observed the Lamb-dip spectrum of the R(1) line in the overtone of hydrogen deuteride (HD). The line position was determined to be 217 105 182.79±0.03_{stat}±0.08_{syst}  MHz (δν/ν=4×10^{-10}), which is the most accurate rovibrational transition ever measured in the ground electronic state of molecular hydrogen. Moreover, from calculations including QED effects up to the order m_{e}α^{6}, we obtained predictions for this R(1) line as well as for the HD dissociation energy, which are less accurate but signaling the importance of the complete treatment of nonadiabatic effects. Provided that the theoretical calculation reaches the same accuracy, the present measurement will lead to a determination of the proton-to-electron mass ratio with a precision of 1.3 parts per billion.

Measurement of the Frequency of the 2 ^{3}S-2 ^{3}P Transition of ^{4}He

The 2 ^{3}S-2 ^{3}P transition of ^{4}He was measured by comb-linked laser spectroscopy using a transverse-cooled atomic beam. The centroid frequency was determined to be 276 736 495 600.0(1.4) kHz, with a fractional uncertainty of 5.1×10^{-12}. This value is not only more accurate but also differs by as much as -49.5  kHz (20σ) from the previous result given by [Cancio Pastor et al., Phys. Rev. Lett. 92, 023001 (2004)PRLTAO0031-900710.1103/PhysRevLett.92.023001; Cancio Pastor et al.Phys. Rev. Lett.97, 139903(E) (2006)10.1103/PhysRevLett.97.139903; Cancio Pastor et al.Phys. Rev. Lett.108, 143001 (2012)10.1103/PhysRevLett.108.143001]. In combination with ongoing theoretical calculations, this work may allow the most accurate determination of the nuclear charge radius of helium.

Cognitive Outcomes After Transcatheter Aortic Valve Implantation: A Metaanalysis

OBJECTIVES

To quantitatively summarize changes in cognitive performance in individuals with severe aortic stenosis undergoing transcatheter aortic valve implantation (TAVI).

DESIGN

Metaanalysis.

PARTICIPANTS

Individuals undergoing TAVI (N = 1,065 (48.5% male) from 18 studies, average age ≥80).

MEASUREMENTS

The MEDLINE, EMBASE, and Cochrane Central databases were searched for original peer-reviewed reports assessing cognitive performance using standardized cognitive tests before and after TAVI. Data were extracted for cognitive scores before TAVI; perioperatively (within 7 days after TAVI); 1, 3, and 6 months after TAVI, and 12 to 34 months after TAVI (over the long term). Standardized mean differences (SMDs) were generated using random-effects models for changes in cognition at each time point. Metaregression analyses were conducted to assess the association between population and procedural characteristics and cognitive outcomes. Risk of bias was assessed.

RESULTS

There were no significant changes from baseline in perioperative cognitive performance (SMD = 0.05, 95% confidence interval (CI) = -0.08-0.18; z = 0.75, P = .46), although overall cognitive performance had improved significantly 1 month after TAVI (SMD = -0.33, 95% CI = -0.50 to -0.16; z = 3.83, P < .001). There were no differences in cognitive performance 3 and 6 months after TAVI or over the long term. Cognitive outcomes were not associated with any covariates in regression analyses.

CONCLUSION

Cognitive performance is preserved after TAVI, suggesting TAVI is not detrimental to cognition.

[Comparison and discussion of different surgical methods used to treat vesicovaginal fistulas]

OBJECTIVE

To compare the feasibility and prognosis of different surgical methods used for vesicovaginal fistulas and to explore the value of electrocoagulation treating small ones.

METHODS

The medical data of 19 patients who had undertaken transvaginal VVF repairs in Peking University People's Hospital between October 2008 and November 2016 were retrospectively collected. The follow-ups were performed. The patients' age ranged from 31 to 55 years with the median age of 48 years and the history length ranged from 1 month to 24 months with the median length of 3 months. Their fistula situation, surgical methods and prognosis were analyzed and the differences and similarities were compared.

RESULTS

Three patients (15.79%) was performed by electrocoagulation, 4 (21.05%) by transvaginal repair, 5 (21.32%) by laparoscopic repair and 7(36.84%) by open operation. Except one patient who rejected urinary catheter and D-J catheters, the rest of the patients discharged with catheters. Twelve patients (63.2%) got full satisfaction with one operation. One of the 3 patients who undertook electrocoagulation repeated the operation for twice and got completely cured within 1 month while the other two undertook the operation once and got dry within 1 month. Three patients who undertook transvaginal repair got dry within 1 month. Two of the 5 patients who undertook laparoscopic repair had readmission for a second operation and the other 3 got dry after operation. Five of the 7 open repair patients got dry while the other 2 attempted other center for treatment.

CONCLUSION

Transvaginal repair has been the main surgery procedure for VVF, but it is limited by the location of fistula and the condition of vaginal. For patients not suitable for transvaginal repair, laparoscopic repair and open surgery are feasible. However both laparoscopic repair and open surgery are more invasive. Based on that, electrocoagulation becomes a better choice. In our research, patients with small and high location fistula treated by electrocoagulation got a higher cure rate and bear less surgical trauma. Electrocoagulation used in the treatment of VVF showed advantages of less trauma, less bleeding and better satisfaction. Fistulas with low location were more suitable for transvaginal repair. Complex VVF, especially with narrow ureteral open and ureteral fistulas, were more suitable for open and laparoscopic repair. As for single and small fistula, the electrocoagulation can be the first choice.

[Effect of nicorandil on ventricular arrhythmia in patients with acute ST-segment elevation myocardial infarction underwent emergent percutaneous coronary intervention treatment]

Objective: To investigate the effect of nicorandil on ventricular arrhythmia in patients with acute ST-segment elevation myocardial infarction (STEMI) treated with emergent percutaneous coronary intervention (PCI). Methods: A total of 120 acute STEMI patients treated with emergent PCI in our hospital from January 2015 to June 2016 were randomly divided into control group and experiment group (n=60 each). Patients in both groups received conventional therapy.Patients in experiment group took 10 mg nicorandil orally before PCI and received oral nicorandil treatment (15 mg/d, three times daily) for 3 days.QT disperse(QTd), correct QTd(QTcd) and the occurrence rate of ventricular arrhythmia were compared between two groups. Results: QTd at 6, 24, 48 and 72 hours((70.6±4.4), (67.2±5.3), (55.7±8.5), (48.2±8.2) ms, respectively) after PCI was significantly lower in the experiment group than those of control group ((77.1±7.1), (71.3±6.5), (65.1±8.1), (57.2±5.4) ms, all P<0.05). The level of QTd was also significantly lower in the experiment group at 6, 24, 48 and 72 hours((77.5±7.7), (67.7±8.6), (61.2±7.5), (52.9±8.4) ms, respectively) after PCI comared to those of control group ((88.6±8.1), (79.2±7.8), (74.4±7.4), (69.6±8.6) ms, all P<0.05). There was no significant difference in the incidence of reperfusion arrhythmia during PCI procedure between the two groups.The prevalence of the ventricular premature beat in the experiment group (25/60, 41.7%) was significantly lower than in the control group(45/60, 75.0%) within 3 days after PCI(P<0.01), the prevalence of the no sustained ventricular tachycardia and ventricular fibrillation in the experiment group(6/60, 10.0%) was also significantly lower than in the control group (18/60, 30.0%, P<0.01) within 3 days after PCI. Conclusions: Nicorandil use prior and post PCI could decrease the occurrence rate of ventricular arrhythmia in STEMI patients undergoing emergent PCI, and this effect might be related with reduced QTd and QTcd post medication.

Comb-locked cavity ring-down saturation spectroscopy

We present a new method of comb-locked cavity ring-down spectroscopy for the Lamb-dip measurement of molecular ro-vibrational transitions. By locking both the probe laser frequency and a temperature-stabilized high-finesse cavity to an optical frequency comb, we realize saturation spectroscopy of molecules with kilohertz accuracy. The technique is demonstrated by recording the R(9) line in the υ = 3 - 0 overtone band of CO near 1567 nm. The Lamb-dip spectrum of such a weak line (transition rate 0.0075 s^-1) is obtained using an input laser power of only 3 mW, and the position is determined to be 191 360 212 770 kHz with an uncertainty of 7 kHz (δν/ν∼3.5×10^-11), which is currently limited by our rubidium clock.

Laser Spectroscopy of the Fine-Structure Splitting in the 2^{3}P_{J} Levels of ^{4}He

The fine-structure splitting in the 2^{3}P_{J} (J=0, 1, 2) levels of ^{4}He is of great interest for tests of quantum electrodynamics and for the determination of the fine-structure constant α. The 2^{3}P_{0}-2^{3}P_{2} and 2^{3}P_{1}-2^{3}P_{2} intervals are measured by laser spectroscopy of the ^{3}P_{J}-2^{3}S_{1} transitions at 1083 nm in an atomic beam, and are determined to be 31 908 130.98±0.13  kHz and 2 291 177.56±0.19  kHz, respectively. Compared with calculations, which include terms up to α^{5}Ry, the deviation for the α-sensitive interval 2^{3}P_{0}-2^{3}P_{2} is only 0.22 kHz. It opens the window for further improvement of theoretical predictions and an independent determination of the fine-structure constant α with a precision of 2×10^{-9}.

[Effect of age on urodynamic parameters of women with urinary incontinence]

OBJECTIVE

To investigate age related changes in urodynamic parameters of women with urinary incontinence.

METHODS

From May 2008 to October 2015, a total of 214 patients diagnosed with urinary incontinence in Peking University People's Hospital was involved in this study. Average age was (56.97±10.68) years, ranging from 30 to 82 years, and average history was (8.44±8.85) years, ranging from one month to 50 years. Urodynamic examinations of each patient were taken before operation routinely in Department of Urology, Peking University People's Hospital. The urodynamic study was composed of non-invasive and invasive procedures. Analysis included maximal flow rate (Qmax), average flow rate, time to Qmax, voiding time, detrusor pressure at Qmax, maximal detrusor pressure, voided volume, post-void residual urine volume (PVR), the total capacity of bladder, first-, strong-, and urge-desire to void, cough leak point pressure (CLPP), and Valsalva leak point pressure (VLPP). Patients were divided into four groups according to age, Kolmogorov-Smirnov test and one-way ANOVA were used for data analysis.

RESULTS

A total of 214 patients were enrolled in this study. The data of Qmax, average flow rate, voided volume, and total capacity of bladder decreased with statistical significance. The value of residual urine volume and voiding time increased without statistical significance, while the value of maximal detrusor pressure decreased.

CONCLUSION

Urodynamic examination data of females with urinary incontinence changes along with the elapse of age, which was mainly observed as age ascends, and the changes in urodynamic parameters of women with urinary incontinence suggest that the value of Qmax, average flow rate, voided volume, and total capacity of bladder decreased significantly, while the value of PVR and the voiding time increased and the value of maximal detrusor pressure decreased.

The 4ν(CH) overtone of 12C2H2: sub-MHz precision spectrum reveals perturbations

The third CH stretching vibration overtone (4ν(CH)) of the acetylene molecule has been a prototype for intra-molecular dynamics studies. Using a sensitive cavity ring-down spectrometer calibrated with precise atomic transitions, the absolute line frequencies of 50 lines of this band have been determined with sub-MHz accuracy, or relatively 2 × 10(-9). The accuracy is also confirmed by the combination differences between the transitions sharing the same upper level. The improved accuracy, two orders of magnitude better than previous studies, allows us to reveal finer ro-vibrational couplings. Fitting of the rotational energies indicates that the J-dependent interactions take place after J > 7. The precise line positions present useful confinements to the models of the intra-molecular interactions of the acetylene molecule.

Normalization of the single atom counting rate in an atom trap

The single atom counting rate of a rare isotope and the loading rate of another stable isotope with an abundance over 10 orders of magnitude larger are measured in one atom trap. The linear correlation between the measured counting/loading rates is examined to determine the (84)Kr/(82)Kr and (85)Kr/(83)Kr ratios of a Kr gas sample. Experiments show that the relative uncertainty is reduced to 1.3% when the single atom counting rate of (85)Kr is normalized by the measured (83)Kr loading rate. The measurement of the normalized single atom counting rate can be used to determine extremely low (10(-16)-10(-11)) isotope abundance. This normalization method is robust and can also be applied in other atomic systems.

Electronic spectroscopy of ytterbium in a neon matrix

The low-lying electronic states of Yb isolated in a solid Ne matrix are characterized through absorption and emission spectroscopy. The absorption spectra of matrix isolated Yb while pumped into its triplet states have been recorded for the first time and the 6s6p (3)P(J) → 5d6s (3)D(1, 2) transition frequencies obtained. Under matrix conditions, the structure of these states is found to be qualitatively the same as in the free atom, but the intersystem crossing rate is observed to be several orders of magnitude greater. A proposed explanation for this is curve crossings between the bound potential energy surface correlated to the 6s6p (1)P(1) state and the potential energy surfaces correlated to the 5d6s (3)D(1, 2) states in isolation. The potentials of the Yb·Ne dimer in its lowest electronic states are computed ab initio and used in a pairwise cluster model to explicitly demonstrate these curve crossings.

Cavity ring-down spectroscopy of Doppler-broadened absorption line with sub-MHz absolute frequency accuracy

A continuous-wave cavity ring-down spectrometer has been built for precise determination of absolute frequencies of Doppler-broadened absorption lines. Using a thermo-stabilized Fabry-Pérot interferometer and Rb frequency references at the 780 nm and 795 nm, 0.1 - 0.6 MHz absolute frequency accuracy has been achieved in the 775-800 nm region. A water absorption line at 12579 cm(-1) is studied to test the performance of the spectrometer. The line position at zero-pressure limit is determined with an uncertainty of 0.3 MHz (relative accuracy of 0.8 × 10(-9)).

Application of cavity ring-down spectroscopy to the Boltzmann constant determination

The Boltzmann constant can be optically determined by measuring the Doppler width of an absorption line of molecules at gas phase. We propose to apply a near infrared cavity ring-down (CRD) spectrometer for this purpose. The superior sensitivity of CRD spectroscopy and the good performance of the near-ir lasers can provide ppm (part-per-million) accuracy which will be competitive to present most accurate result obtained from the speed of sound in argon measurement. The possible influence to the uncertainty of the determined Doppler width from different causes are investigated, which includes the signal-to-noise level, laser frequency stability, detecting nonlinearity, and pressure broadening effect. The analysis shows that the CRD spectroscopy has some remarkable advantages over the direct absorption method proposed before. The design of the experimental setup is presented and the measurement of C2H2 line near 0.8 μm at room temperature has been carried out as a test of the instrument.

Laser-locked, continuously tunable high resolution cavity ring-down spectrometer

A continuous-wave cavity ring-down spectrometer with sub-MHz precision has been built using the sideband of a frequency stabilized laser as the tunable light source. The sideband is produced by passing the carrier laser beam through an electro-optic modulator (EOM) and then selected by a short etalon on resonance. The carrier laser frequency is locked to a longitude mode of a thermo-stabilized Fabry-Perot interferometer (FPI) with a long-term absolute frequency stability of 0.2 MHz (5 × 10(-10)). Broad and precise spectral scanning is accomplished, respectively, by selecting a different longitudinal mode of the FPI and by tuning the radio-frequency driving the EOM. The air broadened water absorption line at 12,321 cm(-1) was studied to test the performance of the spectrometer.

39Ar detection at the 10(-16) isotopic abundance level with atom trap trace analysis

Atom trap trace analysis, a laser-based atom counting method, has been applied to analyze atmospheric 39Ar (half-life=269  yr), a cosmogenic isotope with an isotopic abundance of 8×10(-16). In addition to the superior selectivity demonstrated in this work, the counting rate and efficiency of atom trap trace analysis have been improved by 2 orders of magnitude over prior results. The significant applications of this new analytical capability lie in radioisotope dating of ice and water samples and in the development of dark matter detectors.

[Determination of content of nodakenin in Notopterygium incisum ting from different source by HPLC]

OBJECTIVE

To develop a method for the determination of nodakenin in N. incisum.

METHOD

A HPLC method was used.

RESULT

Y = -9509.1 + 1912709.8X, r = 0.9998. The calibration was linear in range of 0.16-0.64 microgram. The average recovery was 99.7%, RSD 1.1%.

CONCLUSION

The method is appropriate for the determination of nodakenin.

[The research on the expression of rabbit defensin (NP-1) gene in transgenic tomato]

Rabbit defensin NP-1 is one kind of alpha-defensins. It is composed of 33 amino acids. It was firstly extracted from polymorphonnuclear neutrophile of rabbits. It displayed resistance to bacteria, fungi and virus, especially high resistance to bacteria. In our experiments NP-1 gene was constructed into a plant expression vector. Eight transgenic plants containing the rabbit defensin gene (NP-1) were obtained through agrobacterium-mediated transformation. The transgenic plants were analysized by PCR, Southern hybridization, Northern dot blot hybridization and in vitro microbicidical activity against E. coli and Fusarium oxysporum. The results showed that NP-1 gene was transformed into the tomato, and the transgene displayed physiological-level expression. The transgenic tomato also showed resistance to pathogen Fusarium oxysporum in vivo. Our experiments paved a way for pathogen resistance breeding of tomato.

[Effect and mechanism of active fraction A guizhi decoction on dual-directional thermoregulation: effect on heat shock protein in hypothalamus of rats]

OBJECTIVE

To investigate the effect of active fraction A in Guizhi Decoction (Fr.A) on dual-directional thermoregulation and its mechanism of influencing heat shock protein (HSP) in hypothalamus.

METHOD

Using Western blot method to measure HSP of hypothalamus in febrile and hypothermal rats.

RESULTS

Regulating the body temperature in dual-direction, Fr.A could antagonize the decrease of HSP contents of hypothalamus in hypothermal rats induced by aminopyrine, and abate the HSP content in febrile rats induced by yeast.

CONCLUSION

Fr.A adjusts the body temperature through regulating the contents of HSP of hypothalamus in febrile and hypothermal rats.

[Introduction of rabbit defensin NP-1 gene into poplar (P. tomentosa) by Agrobacterium-mediated transformation]

Rabbit defensin NP-1 possesses a broad resistant spectrum to pathogens. In this work, we have transferred the NP-1 gene into poplar plants by Agrobacterium-mediated transformation. PCR amplification and Southern analysis showed that rabbit defensin NP-1 gene was integrated into the poplar genome. The transformation efficiency is about 15.6%. Antimicrobial activity test showed that the extract of transgenic plants inhibited the growth of the tested microbes.

[Monitoring calcium in outer hair cells with confocal microscopy and fluorescence ratios of fluo-3 and fura-red]

Calcium distribution and mobilization during mechanical stimulation in outer hair cells of the guinea pig were monitored using laser scanning confocal microscopy and co-loaded fluo-3 and fura-red fluorescent probes. Spatial calcium gradients were revealed among various subcellular areas. The ratios of the fluorescence intensity of fluo-3 and fura-red were 1.71 +/- 0.85, 1.61 +/- 0.75, 1.47 +/- 0.65 and 1.39 +/- 0.66 for the cytoplasm, the cytoplasmic membrane, the cuticular plate and the nucleus respectively, indicating that free calcium ion concentrations are the highest in the cytoplasm and the lowest in the nucleus. While the calcium concentration remained relatively constant under resting conditions, it increased during mechanical stimulation. The results show that confocal ratio imaging of fluo-3 and fura-red enables us to determine more accurately the subcellular calcium distribution and that the calcium ions make a contribution to the mechanic-electrical transduction in hair cells.

Regeneration of simon poplar (Populus simonii) from protoplast culture

Simon poplar (Populus simonii) protoplasts were isolated from suspension cells, with protoplast yield of 3.8×10(7) g(-1) F. W. They were cultured in a K8P liquid medium containing 13.57μM 2,4-D, 1.07μM NAA and 0.93 μM KT. Protoplast culture was influenced by the plating density, osmotic pressure, and the sources and amounts of nitrogen and carbon in the culture medium. Multiple shoots were produced from protoplast-derived callus after culture on MS medium containing 4.44 μM BA, 2.32μM KT, 2.28 μM ZT, and 0.54μM NAA. Shoots 2-3 cm in height were isolated from the calli and rooted on 1/2 MS medium. After transplantation into pots, the regenerated plants grew vigorously in greenhouse.