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Realizing always atomic translation frequency output, single-mode, high frequency stability, narrow linewidth semiconductor lasers, is one of the ultimate visions of areas related to quantums, such as quantum precision measurement and atomic physics. A single-mode Cs atom 852 nm Faraday laser, utilizing a corner cube retroreflector as the feedback element, is demonstrated and termed as a corner-cube-feedback Faraday laser. Its output frequency remains close to the Cs atomic Doppler-broadened transition line, and through the optimization of the working parameters of Faraday anomalous dispersion optical filter (FADOF), the laser output mode can still remain single, even though the diode current changes from 55 mA to 155 mA (with incremental step of approximately 2 mA) and the diode working temperature varies from $11.8 \,\mathrm{^{\circ }C}$ to $37.2 \,\mathrm{^{\circ }C}$ (with incremental step of approximately $3.5 \,\mathrm{^{\circ }C}$). Also, the single-mode laser oscillation can be achieved over a substantial angular range, specifically between +3$\mathrm{^{\circ }}$and −3$\mathrm{^{\circ }}$, where the angle is defined as the deviation of the incident light from the optical axis of the corner cube. Using the corner-cube retroreflector as external cavity feedback element, the environmental compatibility and reliability can be improved due to the precise reflection of the incident light beam back to its original direction. The most probable linewidth is 8 kHz measured by heterodyne beating with two identical lasers. The output power can achieve a maximum of 57 mW at 155 mA. As for the noise performance of the laser, the typical value of relative intensity noise (RIN) at 10 kHz is lower than −134 dBc/Hz. The pahse noise of the laser is superior than the commerical product. This single-mode corner-cube-feedback Faraday laser can be widely used in quantum precision measurement, such as atomic clocks, atomic gravimeters, and atomic magnetometers, etc.

Atomic optical filters such as Faraday anomalous dispersion optical filters (FADOFs) or similar technologies can achieve very narrow optical bandwidth close to the scale of atomic linewidth, which can be greatly reduced in cold atoms. However, limited by the number of cold atoms and the size of the cold atomic cloud, the number of atoms interacting with the laser is reduced, and the transmission remains as low as 2%. In this work, we introduce the optical pumping into the cold atomic optical filter to solve this problem. Circular polarized optical pumping can produce polarization of the atomic ensemble and induce dichromatic as well as the Faraday rotation. We demonstrate a cold-atom optical filter which operates on the 87Rb 52S1/2 (F=2) to 52P3/2 (F′=2) transition at 780 nm. The filter achieves an ultranarrow bandwidth of 6.6(4) MHz, and its peak transmission is 15.6%, which is nearly 14 times higher than that of the cold-atom optical filter realized by Faraday magneto-optic effect. This scheme can be extended to almost all kinds of atomic optical filters and may find applications in self-stabilizing laser and active optical clock.

The Faraday laser, with Faraday anomalous dispersion optical filter (FADOF) as frequency-selection element, is a natural narrow-bandwidth light source for laser physic experiments. In this work, a dual-frequency (DF) Faraday laser is demonstrated for the first time on Cs D2 line at 852 nm. The frequencies of the two modes of DF Faraday laser hinge on the peak transition frequencies of 852 nm FADOF transmittance spectrum corresponding to the ground state F=4 and F=3. The frequency difference between the two modes is tunable over a range of 1.4 GHz with the temperature of Cs vapor cell inside the FADOF. The linewidth of each laser mode is less than 33 kHz. Furthermore, the most probable linewidth of the beat-note spectra between the two modes is 902.95 Hz at different vapor-cell temperatures. Such a DF Faraday laser has many potential applications in atomic physics, such as sub-Doppler spectroscopy and coherent population trapping atomic clocks.

Abstract Background Respiratory syncytial virus (RSV) is the most common viral cause of pediatric bronchiolitis and pneumonia worldwide. Risk factors for high mortality and prolonged morbidity after RSV infection include premature birth, bronchopulmonary dysplasia, congenital heart disease, and Down syndrome. However, some previously healthy, full-term children who are infected with RSV also require hospitalization and even experience severe sequelae or death. Case presentation In this report, we present the case of an RSV-associated death of a child who was born at full-term and developed normally up to the age of 2 years old. Cardiopulmonary arrest occurred within 3 days after the onset of symptoms, which included cough and high fever. Complete brain edema was prominent, and encephalopathy was developing. Viral antigen detection and microbiome analyses of oral swab and nasopharyngeal aspirate specimens verified an RSV infection, while bacterial culture of blood specimens yielded negative results. The RSV strain detected in this patient was subtyped as RSVB9, and no mutation was found in the six antigenic sites for targeted drugs or vaccines. Conclusions The patient had a severe infection associated with RSV, which was very likely the cause of her central nervous system infection and acute neurological complications.

Background. Tuberculosis is an urgent public health problem caused by Mycobacterium tuberculosis infection. Many factors, including host genetic factors, are involved in tuberculosis pathogenesis. The SLC11A1 gene (formerly NRAMP1) is a primary candidate for association with tuberculosis susceptibility. Methods. We examined the association between SLC11A1 polymorphisms and susceptibility to tuberculosis in Han Chinese children. The study included 136 pediatric patients with tuberculosis and 435 pediatric control subjects. Polymerase chain reaction restriction fragment-length polymorphism analysis was performed with blood samples to distinguish allele genotypes of INT4 (a G→C single nucleotide change in intron 4, 469 + 14G/C) and the 3′UTR (TGTG deletion in the 3′ untranslated region, 1729 + 55del) in the SLC11A1 gene. Differences in genotype frequency were analyzed for patients with tuberculosis and control subjects. Results. We did not identify any statistically significant differences between the tuberculosis and control groups with regard to the frequency of genotype variants G/C and C/C at the INT4 locus. The frequency of genotype variants (TGTG +/delete and TGTG delete/delete) was significantly higher in the tuberculosis group than in the control group at the 3′UTR locus. Differences in genotype distribution at the 3′UTR locus were only identified in female subjects, with a greater number of variant genotypes in the tuberculosis group. Conclusions. Variant genotypes at the 3′UTR locus in the SLC11A1 gene were associated with pediatric tuberculosis in Chinese patients. Patient sex may affect the outcome of M. tuberculosis infection in children. [ABSTRACT FROM AUTHOR]