[Impact of VA-ECMO combined with IABP and timing on outcome of patients with acute myocardial infarction complicated with cardiogenic shock]

Objective: To investigate the impact of combined use and timing of arterial-venous extracorporeal membrane oxygenation (VA-ECMO) with intra-aortic balloon pump (IABP) on the prognosis of patients with acute myocardial infarction complicated with cardiogenic shock (AMICS). Methods: This was a prospective cohort study, patients with acute myocardial infarction and cardiogenic shock who received VA-ECMO support from the Heart Center of Lanzhou University First Hospital from March 2019 to March 2022 in the registration database of the Chinese Society for Extracorporeal Life Support were enrolled. According to combination with IABP and time point, patients were divided into VA-ECMO alone group, VA-ECMO+IABP concurrent group and VA-ECMO+IABP non-concurrent group. Data from 3 groups of patients were collected, including the demographic characteristics, risk factors, ECG and echocardiographic examination results, critical illness characteristics, coronary intervention results, VA-ECMO related parameters and complications were compared among the three groups. The primary clinical endpoint was all-cause death, and the safety indicators of mechanical circulatory support included a decrease in hemoglobin greater than 50 g/L, gastrointestinal bleeding, bacteremia, lower extremity ischemia, lower extremity thrombosis, acute kidney injury, pulmonary edema and stroke. Kaplan-Meier survival curves were used to analyze the survival outcomes of patients within 30 days of follow-up. Using VA-ECMO+IABP concurrent group as reference, multivariate Cox regression model was used to evaluate the effect of the combination of VA-ECMO+IABP at different time points on the prognosis of AMICS patients within 30 days. Results: The study included 68 AMICS patients who were supported by VA-ECMO, average age was (59.8±10.8) years, there were 12 female patients (17.6%), 19 cases were in VA-ECMO alone group, 34 cases in VA-ECMO+IABP concurrent group and 15 cases in VA-ECMO+IABP non-concurrent group. The success rate of ECMO weaning in the VA-ECMO+IABP concurrent group was significantly higher than that in the VA-ECMO alone group and the VA-ECMO+IABP non-concurrent group (all P<0.05). Compared with the ECMO+IABP non-concurrent group, the other two groups had shorter ECMO support time, lower rates of acute kidney injury complications (all P<0.05), and lower rates of pulmonary edema complications in the ECMO alone group (P<0.05). In-hospital survival rate was significantly higher in the VA-ECMO+IABP concurrent group (28 patients (82.4%)) than in the VA-ECMO alone group (9 patients) and VA-ECMO+IABP non-concurrent group (7 patients) (all P<0.05). The survival rate up to 30 days of follow-up was also significantly higher surviving patients within were in the ECMO+IABP concurrent group (26 cases) than in VA-ECMO alone group (9 patients) and VA-ECMO+IABP non-concurrent group (4 patients) (all P<0.05). Multivariate Cox regression analysis showed that compared with the concurrent use of VA-ECMO+IABP, the use of VA-ECMO alone and non-concurrent use of VA-ECMO+IABP were associated with increased 30-day mortality in AMICS patients (HR=2.801, P=0.036; HR=2.985, P=0.033, respectively). Conclusions: When VA-ECMO is indicated for AMICS patients, combined use with IABP at the same time can improve the ECMO weaning rate, in-hospital survival and survival at 30 days post discharge, and which does not increase additional complications.

CircRNA 010567 improves myocardial infarction rats through inhibiting TGF-β1

OBJECTIVE

To observe the intervention effect of circular ribonucleic acid (circRNA) 010567 on myocardial infarction (MI)-induced myocardial fibrosis (MF) in rats, and to explore whether its mechanism of action is related to the regulation on the transforming growth factor-β1 (TGF-β1) signaling pathway.

MATERIALS AND METHODS

The rat model of acute MI was established using ligation of the left anterior descending coronary artery. Model rats were randomly divided into circRNA 010567 siRNA group and Model group, with sham operation group as Control group. The effects of circRNA 010567 on the cardiac function, MF, myocardial apoptosis, mRNA, and protein expression levels of TGF-β1 and Smad3 in heart tissues of MI rats were detected using the small animal ultrasound system, Masson staining, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining, reverse transcription-polymerase chain reaction (RT-PCR), and Western blotting, respectively.

RESULTS

Compared with Control group, Model group had significantly decreased cardiac function, significantly lower left ventricular ejection fraction (LVEF), and left ventricular fractional shortening (LVFS), markedly increased left ventricular end-diastolic diameter (LVDd), and left ventricular end-systolic diameter (LVDs), severe MF, as well as a significantly higher apoptosis rate of myocardial cells, and evidently increased mRNA and protein levels of TGF-β1 and Smad3 in heart tissues. Compared with Model group, circRNA 010567 siRNA group had evidently improved cardiac function, significantly higher LVEF and LVFS, markedly decreased LVDd and LVDs, alleviated MF, a significantly lower apoptosis rate of myocardial cells, and evidently decreased mRNA and protein levels of TGF-β1 and Smad3 in heart tissues.

CONCLUSIONS

CircRNA 010567 siRNA can improve the cardiac function, alleviate the MF, and inhibit the myocardial apoptosis, thereby further suppressing MI-induced MF, whose mechanism may be related to the inhibition on the TGF-β1 signaling pathway.

Effects of butylphthalide on oxidative stress and inflammatory response in rats with myocardial infarction through Akt/Nrf2 signaling pathway

OBJECTIVE

The aim of this study was to investigate the effects of butylphthalide on oxidative stress and inflammatory response in rats with myocardial infarction through the protein kinase B/nuclear factor E2-related factor 2 (Akt/Nrf2) signaling pathway.

MATERIALS AND METHODS

A total of 36 Sprague-Dawley rats were randomly divided into three groups, including sham group (n=12), model group (n=12) and butylphthalide group (n=12). In the sham group, the heart was exposed, and normal saline was intraperitoneally injected after the operation. In the model group, acute myocardial infarction (AMI) model was established, and normal saline was intraperitoneally injected after the operation. In the butylphthalide group, AMI model was established, and butylphthalide was intraperitoneally injected after the operation. After intervention for 4 weeks, the rats were killed, and the samples were collected. The morphology of heart tissues was observed via hematoxylin-eosin (HE) staining. The expression of nicotinamide adenine dinucleotide phosphate oxidase-1 (NOX-1) was detected via immunohistochemistry. The protein expressions of phosphorylated Akt (p-Akt) and p-Nrf2 were detected via Western blotting. Moreover, the content of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) was detected via enzyme-linked immunosorbent assay (ELISA). The messenger ribonucleic acid (mRNA) expression levels of IL-1β, TNF-α and NOX-1 were detected via quantitative Polymerase Chain reaction (qPCR). Furthermore, the apoptosis rate of the cells was detected via terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay.

RESULTS

The morphology of heart tissues was significantly damaged in the model group and butylphthalide group compared with the sham group. However, it was significantly improved in the butylphthalide group when compared with the model group. The expression level of NOX-1 increased markedly in the model group and butylphthalide group compared with the sham group (p<0.05). However, it was remarkably reduced in the butylphthalide group compared with the model group (p<0.05). Meanwhile, the protein expression levels of p-Akt and p-Nrf2 were significantly higher in the model group and butylphthalide group than those of the sham group (p<0.05). However, the protein expression levels of p-Akt and p-Nrf2 in the butylphthalide group were remarkably lower than the model group (p<0.05). The mRNA expression levels of IL-1β, TNF-α and NOX-1 were markedly higher in the model group and butylphthalide group than those of the sham group (p<0.05). However, they remarkably declined in the butylphthalide group compared with the model group (p<0.05). In addition, the content of IL-1β and TNF-α increased in the model group and butylphthalide group when compared with the sham group (p<0.05). The content of IL-1β and TNF-α in the butylphthalide group was significantly lower than the model group (p<0.05). Furthermore, the apoptosis rate was significantly higher in the model group and butylphthalide group than the sham group (p<0.05), which was significantly lower in the butylphthalide group than the model group (p<0.05).

CONCLUSIONS

Butylphthalide inhibits inflammatory and oxidative stress responses after AMI by regulating the Akt/Nrf2 signaling pathway, thereby inhibiting myocardial apoptosis and benefiting the morphological repair of myocardial tissues.

CircHIPK3 aggravates myocardial ischemia-reperfusion injury by binding to miRNA-124-3p

OBJECTIVE

To elucidate whether circHIPK3 could inhibit proliferation and induce apoptosis of cardiomyocytes via binding to miRNA-124-3p, thus aggravating myocardial ischemia/reperfusion (IR) injury.

MATERIALS AND METHODS

CircHIPK3 expression in HCM cells simulated with myocardial I/R was determined by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). Influences of circHIPK3 on myocardial injury marker levels of lactate dehydrogenase (LDH), malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) in the in vitro model of myocardial I/R were evaluated using the relative commercial kits. The regulatory effects of circHIPK3 on proliferative ability and apoptosis of simulated HCM cells were examined by Cell Counting Kit-8 (CCK-8) assay and flow cytometry, respectively. Dual-Luciferase reporter gene assay was conducted to verify the binding of circHIPK3 to miRNA-124-3p. Finally, the roles of the circHIPK3/miRNA-124-3p axis in regulating apoptotic gene expressions and cardiomyocyte repair after myocardial I/R were explored.

RESULTS

CircHIPK3 was highly expressed in HCM cells with simulated myocardial I/R relative to those with normoxic treatment. The overexpression of circHIPK3 in simulated HCM cells decreased levels of LDH, SOD and GSH-PX, whereas increased the MDA level. Inhibited proliferation and accelerated apoptosis were observed in simulated HCM cells overexpressing circHIPK3. Western blot analyses illustrated that circHIPK3 overexpression upregulated pro-apoptotic Bax, and downregulated anti-apoptotic Bcl-2. Subsequently, we confirmed the binding between circHIPK3 and miRNA-124-3p. Rescue experiments demonstrated that circHIPK3 overexpression reversed the protective effects of miRNA-124-3p on myocardial I/R and cardiomyocyte apoptosis.

CONCLUSIONS

CircHIPK3 inhibits proliferative ability and induces apoptosis of cardiomyocytes after myocardial I/R injury by binding to miRNA-124-3p, which may serve as a potential therapeutic target for I/R.

Coding for stable transmission of W-band radio-over-fiber system using direct-beating of two independent lasers

We demonstrate experimentally Manchester (MC) coding based W-band (75 - 110 GHz) radio-over-fiber (ROF) system to reduce the low-frequency-components (LFCs) signal distortion generated by two independent low-cost lasers using spectral shaping. Hence, a low-cost and higher performance W-band ROF system is achieved. In this system, direct-beating of two independent low-cost CW lasers without frequency tracking circuit (FTC) is used to generate the millimeter-wave. Approaches, such as delayed self-heterodyne interferometer and heterodyne beating are performed to characterize the optical-beating-interference sub-terahertz signal (OBIS). Furthermore, W-band ROF systems using MC coding and NRZ-OOK are compared and discussed.

A scalable and continuous-upgradable optical wireless and wired convergent access network

In this work, a scalable and continuous upgradable convergent optical access network is proposed. By using a multi-wavelength coherent comb source and a programmable waveshaper at the central office (CO), optical millimeter-wave (mm-wave) signals of different frequencies (from baseband to > 100 GHz) can be generated. Hence, it provides a scalable and continuous upgradable solution for end-user who needs 60 GHz wireless services now and > 100 GHz wireless services in the future. During the upgrade, user only needs to upgrade their optical networking unit (ONU). A programmable waveshaper is used to select the suitable optical tones with wavelength separation equals to the desired mm-wave frequency; while the CO remains intact. The centralized characteristics of the proposed system can easily add any new service and end-user. The centralized control of the wavelength makes the system more stable. Wired data rate of 17.45 Gb/s and w-band wireless data rate up to 3.36 Gb/s were demonstrated after transmission over 40 km of single-mode fiber (SMF).

Optical Constants of Two Typical Liquid Crystals 5CB and PCH5 in the THz Frequency Range

The complex refractive indices of two benchmark nematic liquid crystal,4-4 '-n-pentyl-cyanobiphenyl (5CB) and 4-(trans-4'pentylcyclohexyl)-benzonitrile (PCH5) have been determinedin the frequency range from 0.2 to 0.8 THz. The technique of coherent THztime-domain spectroscopy (THz-TDS) was used. We show that the birefringenceof 5CB is in the range of 0.15 to 0.21, while that of PCH is from 0.01 to0.08. Both liquid crystals exhibit relatively small absorption in thisfrequency range. The large birefringence of 5CB indicates possible applications of liquid-crystal-based devices for modulation and polarizationcontrol of electromagnetic radiation in the THz frequency range.

100 GHz ultra-wideband (UWB) fiber-to-the-antenna (FTTA) system for in-building and in-home networks

Fiber-to-the-antenna (FTTA) system can be a cost-effective technique for distributing high frequency signals from the head-end office to a number of remote antenna units via passive optical splitter and propagating through low-loss and low-cost optical fibers. Here, we experimentally demonstrate an optical ultra-wideband (UWB) - impulse radio (IR) FTTA system for in-building and in-home applications. The optical UWB-IR wireless link is operated in the W-band (75 GHz - 110 GHz) using our developed near-ballistic unitraveling-carrier photodiode based photonic transmitter (PT) and a 10 GHz mode-locked laser. 2.5 Gb/s UWB-IR FTTA systems with 1,024 high split-ratio and transmission over 300 m optical fiber are demonstrated using direct PT modulation.

An impact rotary motor based on a fiber torsional piezoelectric actuator

A prototype small impact rotary motor has been fabricated based on a newly developed torsional actuator which is 15.0 mm long and 1.0 mm in diameter. The motor can rotate when it is powered with a saw-shaped voltage. The experimental results show that its angular speed is proportional to both the driving voltage's amplitude and the frequency under 1 kHz. The large nonlinearity occurs at higher driving frequency due to the resonance of the partial mechanical structure of the motor. The motor can rotate at a speed of 90 rpm with a saw-shaped driving voltage of 600 V(p.-p.) at 8 kHz, and produce a stall torque of 80 microN m with 1000 V(p.-p.) at 3 kHz.

Cutaneous innervation in chronic inflammatory demyelinating polyneuropathy

The authors evaluated epidermal nerve density (END) and thermal thresholds in 18 patients with chronic inflammatory demyelinating polyneuropathy (CIDP). END of patients with CIDP were lower than those of controls (4.5 +/- 2.9 vs 10.5 +/- 3.9 fibers/mm, p < 0.001). Reduced END were associated with autonomic symptoms. Thermal thresholds of patients with CIDP were elevated (88.2% for warm stimuli and 70.6% for cold stimuli). Patients with CIDP have small-fiber sensory and autonomic neuropathies.

Acute sensory ataxic neuropathy associated with monospecific anti-GD1b IgG antibody

The authors describe two patients with acute sensory ataxic neuropathy. Both had a profound loss of proprioception and generalized areflexia. High titers of monospecific anti-GD1b IgG antibody were detected in their sera during the acute phase. Sensory ataxia resolved within 2 weeks after the onset. Taken together with the induction of experimental sensory ataxic neuropathy sensitized with GD1b ganglioside, GD1b may be a target molecule for autoantibody in some patients with acute sensory ataxic neuropathy.

Degeneration of nociceptive nerve terminals in human peripheral neuropathy

Patients with peripheral neuropathy have symptoms involving small-diameter nociceptive nerves and elevated thermal thresholds. Nociceptive nerves terminate in the epidermis of the skin and are readily demonstrated with the neuronal marker, protein gene product 9.5 (PGP 9.5). To investigate the pathological characteristics of elevated thermal thresholds, we performed PGP 9.5 immunocytochemistry on 3 mm punch skin biopsies (the forearm and the leg) from 55 normal subjects and 35 neuropathic patients. Skin innervation was evaluated by quantifying epidermal nerve densities. Epidermal nerve densities were reduced in neuropathic patients compared to normal subjects. Epidermal nerve densities were variably correlated with thermal thresholds. The proportion of neuropathic patients with reduced epidermal nerve densities was larger than the proportion of neuropathic patients with elevated thermal thresholds. These results indicated that degeneration of epidermal nerve terminals preceded the elevation of thermal thresholds. Skin biopsy together with immunocytochemical demonstration of epidermal innervation offers a new approach to evaluate small-fiber sensory neuropathy.

Mode-locked diode-pumped self-frequency-doubling neodymium yttrium aluminum borate laser

As far as we know this is the first report on picosecond green-light generation from an actively mode-locked diode-pumped self-doubling neodymium yttrium aluminum borate (NYAB) laser. The pulse width is approximately 100 ps and is limited by imperfect antireflection coating and the intracavity doubling effect. The green average output power of this laser for mode-locked operation was more than 12 times higher than that for the continuous wave NYAB laser. The polarization state of the laser can be switched from ordinary to extraordinary rays by displacement of the pump spot. The polarization ratio can be better than 200 without any intracavity polarization element.

Effects of intracavity dispersion on the starting dynamics of continuous-wave passively mode-locked Ti:sapphire/DDI lasers

Through analysis of transient autocorrelation traces, we show that intracavity dispersion significantly affects the number of initially oscillating modes as well as the buildup of passive mode locking in picosecond and femtosecond lasers.

Tunable multiterahertz beat signal generation from a two-wavelength laser-diode array

We report, for the first time to our knowledge, generation of a tunable miltiterahertz modulation signal on an optical carrier directly from a single laser source. The modulation frequency, which can be tuned from 0.15 THz to more than 7 THz, is the beat note obtained by varying the spectral separation between the coaxial two-color output of a two-wavelength laser-diode array from 0.32 to 17 nm. The frequency characteristics of the terahertz beat note are determined with a noncollinear intensity autocorrelator.

Starting dynamics of a cw passively mode-locked picosecond Ti:sapphire/DDI laser

We show that, for a cw passively mode-locked picosecond Ti:sapphire/DDI laser, the first autocorrelation trace with negligible cw background occurs at a delay time of 20 mu;s, or 1600 round trips from the first relaxationoscillation peak. The trace suggests that the pulse consists of a primary pulse as short as 4.4 ps and of small secondary pulses that form a much wider pedestal of the trace, each containing approximately 50% of the photon energy. Nearly transform-limited approximately 5-ps-wide Gaussian pulses were observed at a delay time of 40 mu;s. After 45 mu;s, the optical spectrum broadened considerably, and the time-bandwidth product increased to 4 in the steady state (after 60 micros).

Dual-wavelength actively mode-locked laser-diode array with an external grating-loaded cavity

We report the generation of dual-wavelength picosecond pulses by use of a commercial laser-diode array. The laser cavity incorporated a folded dispersive delay line with a V-shaped double-stripe mirror. The spectral separation of the laser output at the two wavelengths can be tuned from 2 to 11 nm. The actively mode-locked pulse widths at the two wavelengths were both 29 ps. Cross-correlation and power-spectrum measurements indicated that the two-color pulses were synchronized with an absolute timing jitter of less than 1 ps (instrument limited).

Triangularly phase-modulated optical fiber ring resonator sensor

An optical fiber ring resonatory sensor system has been demonstrated by applying a triangular phase modulation signal to a fiber loop. The dynamic range for detection of optical phase change is 2pi. The sensor is linear within this range. The minimum detectable optical phase change is 1.5 x10(-4) rad/Hz((1/2)).

Two-frequency fiber-optic sensor system using high-birefringence optical fiber

A fiber sensor system based on high-birefringence optical fiber and a frequency-stabilized He-Ne Zeeman laser (lambda = 0.6328 microm) has been demonstrated. The small path-length changes of interest are extracted from the amplitude or phase of the laser beat frequency by using either the phase-sensitive detection or the phase-demodulation technique. A minimum detectable optical phase delay of 1.5 x 10(-6) rad/Hz((1/2)) or 17 x 10(-6) rad/Hz((1/2)) has been achieved.

Scale-factor-stabilized fiber-optic gyroscope by deep phase modulation

A scale-factor-stabilized fiber-optic gyroscope by deep phase modulation is demonstrated. There are two servo loops included in this system. The first servo loop is used for stabilization of the light intensity output of the fiber-optic gyroscope. The second loop is used to stabilize the phase-modulation index. The third-harmonic frequency of the phase-modulation signal is used for detection of the Sagnac phase shift by the lock-in technique.

Triangular phase-modulation approach to an open-loop fiber-optic gyroscope

A new approach to an open-loop, all-fiber gyroscope with a wide dynamic range and a linear scale factor is described. For signal processing, the Sagnac phase shift is converted into a phase shift in the low-frequency electrical signal by using a triangular phase-modulation waveform followed by gate switching. The basic principle of this technique and experimental results are reported.

Buildup of steady-state picosecond pulses in an actively mode-locked laser-diode array

We have studied experimentally the temporal and spectral characteristics of an actively mode-locked laserdiode array in an external cavity as it evolves to the steady state. It is found that the buildup time to steadystate picosecond pulses takes less than 45 round trips. The number of clusters of the longitudinal-mode spectrum reduces during the evolution and finally approaches a steady-state spectral distribution with the pulse energy mainly distributed among a few clusters near the line center.

Multiplexed fiber-optic sensors using a dual-slope frequency-modulated source

We propose and demonstrate a multiplexed fiber-optic sensor system using a dual-slope (triangular) frequency-modulated laser source. The restrictions in the selection of beat frequencies of the multiplexed sensors in previous studies that employed ramp modulation wave forms are eliminated.

Precision displacement measurement by active laser heterodyne interferometry

We demonstrate an active laser heterodyne interferometer which can automatically compensate environmental disturbances and is capable of precision displacement measurement. Two Zeeman He-Ne lasers were employed. Laser II was used as the light source to stabilize the interferometer by using a piezomirror in a feedback loop. The hetereodyne signal of the two lasers was used to directly calibrate mirror displacement, with the wavelength of laser I tuned to compensate change in the interference signal due to displacement only. Separation of the contributions to the interference signal from displacement and external disturbances was accomplished by using polarization optics. This interferometer was used to measure the hysteresis of a piezoelectric transducer (PZT) over a dynamic range of 0.5 microm with a resolution of +/-0.8 nm.

Scale-factor-stabilized fiber-optic gyroscope based on a spectrum-broadened laser-diode source

A spectrum-broadened laser-diode source that uses the optical feedback and current-modulation effects has been adopted as the light source of a fiber-optic gyroscope to reduce the inherent phase noise. The scale factor of the gyroscope has also been stabilized.

Fiber-optic gyroscopes based on polarization scrambling

A novel fiber-optic gyroscope with a single-mode diode laser as the light source and two polarization scramblers as time-varying depolarizers is demonstrated. This arrangement reduces the nonreciprocal phase noise induced by the cross coupling between polarization modes in single-mode fibers. The experimental results show that a phase-noise reduction factor of 18 can be achieved.

Buildup of steady-state subpicosecond and femtosecond pulses in a colliding-pulse mode-locked ring dye laser

We show for the first time, to our knowledge, that the buildup time to steady-state femtosecond pulses in a typical colliding-pulse mode-locked dye laser (lambda = 620 nm) with compensating prisms is 15 microsec after the pulses have been completely modulated. For a similar laser without the compensating prisms, the buildup time is 40 microsec and exhibits interesting oscillatory behavior in the initial stage.

Interferometric measurements of the thickness of nematic liquid crystal films with a free surface

We demonstrate two interferometric methods for measuring the thickness of nematic liquid crystal films with a free surface. The accuracy of either method is better than +/-1 %.

Identification of cell wall antigens associated with a large conjugative plasmid encoding phage resistance and lactose fermentation ability in lactic streptococci

In order to begin to analyze the gene products encoded by phage resistance plasmids in lactic streptococci, we identified phage-resistance plasmids by screening resistant strains from commercial starter cultures for the ability to carry out unselected cotransfer, by conjugation, of phage resistance with lactose fermentation ability (lac+). In this fashion, we identified a large (90 kilobases) plasmid, pCLP51R, that encodes the lac+ marker, resistance to a lytic phage called LP10G (1pr+), high-frequency conjugal donor ability (hft+), and clumpy growth of host bacteria in broth culture (clu+). The mechanism of resistance conferred by this plasmid appears to involve interference with a step in the phage replication cycle that occurs after the initial attachment of the phage. Polyacrylamide gel electrophoresis of cell surface extracts of isogenic strains, carrying or lacking pCLP51R, combined with immunoblotting analysis, showed that there were several plasmid-related differences in the banding pattern of low molecular weight proteins and that the plasmid resulted in production of several unique antigenic polypeptides in the size range of 15-30 kd, as well as modification of chromosomally encoded antigens to different molecular weight forms.

Quasi-static electric-field-enhanced diffraction effects in a nematic liquid-crystal film

A quasi-static electric field can enhance laser-induced diffraction rings from a nematic liquid-crystal film. This phenomenon is shown to be the combined result of the critical behavior of the sample at the Freedericksz transition and the nonlinear coupling of the optical and quasi-static electric fields.

Detection of individual atoms in helium buffer gas and observation of their real-time motion

Single atoms are detected and their motion measured for the first time to our knowledge by the fluorescence photon- burst method in the presence of large quantities of buffer gas. A single-clipped digital correlator records the photon burst in real time and displays the atom's transit time across the laser beam. A comparison is made of the special requirements for single-atom detection in vacuum and in a buffer gas. Finally, the probability distribution of the bursts from many atoms is measured. It further proves that the bursts observed on resonance are due to single atoms and pot simply to noise fluctuations.