Precision Measurement of the Helium Flux in Primary Cosmic Rays of Rigidities 1.9 GV to 3 TV with the Alpha Magnetic Spectrometer on the International Space Station

Knowledge of the precise rigidity dependence of the helium flux is important in understanding the origin, acceleration, and propagation of cosmic rays. A precise measurement of the helium flux in primary cosmic rays with rigidity (momentum/charge) from 1.9 GV to 3 TV based on 50 million events is presented and compared to the proton flux. The detailed variation with rigidity of the helium flux spectral index is presented for the first time. The spectral index progressively hardens at rigidities larger than 100 GV. The rigidity dependence of the helium flux spectral index is similar to that of the proton spectral index though the magnitudes are different. Remarkably, the spectral index of the proton to helium flux ratio increases with rigidity up to 45 GV and then becomes constant; the flux ratio above 45 GV is well described by a single power law.

Precision Measurement of the Proton Flux in Primary Cosmic Rays from Rigidity 1 GV to 1.8 TV with the Alpha Magnetic Spectrometer on the International Space Station

A precise measurement of the proton flux in primary cosmic rays with rigidity (momentum/charge) from 1 GV to 1.8 TV is presented based on 300 million events. Knowledge of the rigidity dependence of the proton flux is important in understanding the origin, acceleration, and propagation of cosmic rays. We present the detailed variation with rigidity of the flux spectral index for the first time. The spectral index progressively hardens at high rigidities.

Pyrosequencing Analysis of Subgingival Microbiota in Distinct Periodontal Conditions

Subgingival microorganisms are potentially associated with periodontal diseases. However, changes in the subgingival microbiota during the progress of periodontal diseases are poorly understood. In this study, we analyzed bacterial communities in the subgingival paper point samples from 32 Korean individuals with no sign of disease, gingivitis, or periodontitis using 454 FLX Titanium pyrosequencing. A total of 256,113 reads representing 26 phyla, 433 genera, and 1,016 species were detected. Bacteroidetes, Fusobacteria, Synergistetes, and Spirochaetes were the abundant phyla in periodontitis subjects, whereas Firmicutes and Proteobacteria were identified as the dominant phyla in the gingivitis and healthy subjects, respectively. Although high levels of Porphyromonas, Fusobacterium, Fretibacterium, Rothia, Filifactor, and Treponema genera were observed in the periodontitis subjects, Streptococcus, Capnocytophaga, Leptotrichia, and Haemophilus genera were found at high frequency in the gingivitis subjects. Species including Porphyromonas gingivalis, Fusobacterium nucleatum, and Fretibacterium fastidiosum were significantly increased in periodontitis subjects. On the other hand, Streptococcus pseudopneumoniae, Haemophilus parainfluenzae, and Leptotrichia hongkongensis were preferentially observed in the gingivitis subjects. Intriguingly, the halophile Halomonas hamiltonii was revealed as a predominant species in the healthy subjects. Based on Fast UniFrac analysis, distinctive bacterial clusters were classified for the healthy, gingivitis, and periodontitis state. The current findings might be useful for understanding the pathogenesis, diagnosis, and treatment of periodontal diseases.

Fluoxetine and S-citalopram inhibit M1 activation and promote M2 activation of microglia in vitro

Increasing evidence has suggested that microglia dysfunction plays an important role in the pathogenesis of depression. Both classical activation (M1 activation) and alternative activation (M2 activation) may be involved in the process. M1-activated microglia secrete various pro-inflammatory cytokines and neurotoxic mediators, which may contribute to the development of depression, while M2-activated microglia promote tissue reconstruction by releasing anti-inflammatory cytokines involved in the process of depression. Selective serotonin reuptake inhibitors (SSRIs) are first-line treatments for depression, and their effects on immune system modulation have recently gained attention. Several studies have suggested that SSRIs affect the M1 activation of microglia, but results have varied. In addition, little is known about the effect of SSRIs on M2 activation in depression. The aim of this study was to investigate the effects of fluoxetine and S-citalopram, two widely used SSRIs in clinical, on both the M1 and M2 activation of microglia (the murine BV2 cell line and mouse primary microglia cell). The indexes of activation were measured by real-time polymerase chain reaction (PCR), enzyme-linked immunosorbent assay (ELISA) and Western blot. The present results showed that both fluoxetine and S-citalopram significantly down-regulated the indexes of M1 activation and up-regulated the M2 activation indexes on mRNA and protein levels either in cell line or primary cells. Taken together, the results suggested that fluoxetine and S-citalopram modulated the immune system by inhibiting M1 activation and by improving M2 activation of microglia and that the immune system modulation may partially mediate the therapeutic effects of antidepressant drugs-SSRIs.

Multiscale stress-strain characterization of onion outer epidermal tissue in wet and dry states

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PREMISE OF THE STUDY

Quantitative measurements of water's effects on the tension response of plant tissue will assist in understanding the regulatory mechanism underlying expansive growth. Such measurements should be multiscale in nature to account for plants' hierarchical structure.•

METHODS

Outer onion epidermal tissues were cut and bonded to uniaxial displacement-controlled mechanical loading devices to apply and measure the force on the sample. Fluorescent polystyrene beads (500 nm in diameter) were dispersed on the sample surface under various levels of tensile load conditions to obtain displacement maps with a confocal fluorescent microscope. The resulting strain was measured using a digital image correlation technique by tracking individual bead displacements. The applied forces were obtained by measuring the displacement of the calibrated force-sensing device. Tissue- and cell-scale mechanical properties were quantified by calculating the applied stress and the corresponding global and local strains.•

KEY RESULTS

The Young's modulus values of individual cell walls of dehydrated and rehydrated samples were 3.0 ± 1.0 GPa and 0.4 ± 0.2 GPa, respectively, and are different from the Young's modulus values of the global tissue-scale dehydrated and rehydrated samples, which were 1.9 ± 0.3 GPa and 0.08 ± 0.02 GPa, respectively. Poisson's ratio increased more than 3-fold due to hydration.•

CONCLUSION

The results on global, cell-to-cell, and point-to-point mechanical property variations suggest the importance of the mechanical contribution of extracellular features including the middle lamella, cell shape, and dimension. This study shows that a multiscale investigation is essential for fundamental insights into the hierarchical deformation of biological systems.

Precision Measurement of the (e^{+}+e^{-}) Flux in Primary Cosmic Rays from 0.5 GeV to 1 TeV with the Alpha Magnetic Spectrometer on the International Space Station

We present a measurement of the cosmic ray (e^{+}+e^{-}) flux in the range 0.5 GeV to 1 TeV based on the analysis of 10.6 million (e^{+}+e^{-}) events collected by AMS. The statistics and the resolution of AMS provide a precision measurement of the flux. The flux is smooth and reveals new and distinct information. Above 30.2 GeV, the flux can be described by a single power law with a spectral index γ=-3.170±0.008(stat+syst)±0.008(energy scale).

Evaluation of a 2-channel portable device and a predictive model to screen for obstructive sleep apnea in a laboratory environment

BACKGROUND

Various portable monitors for identifying obstructive sleep apnea (OSA) have been investigated and reported to enable accurate recording of OSA severity. However, more information is needed from different populations. This study was conducted to evaluate the efficiency of a portable 2-channel sleep apnea device (SleepView) for screening OSA in the Chinese population.

METHODS

Ninety-three consecutive subjects underwent simultaneous SleepView testing and laboratory polysomnography (PSG) monitoring. Data were collected and blindly analyzed. The efficiency of the SleepView device and a newly established predictive model for identifying OSA was evaluated in comparison with PSG.

RESULTS

Good agreement was evident between the SleepView and PSG based on the apnea-hypopnea index (AHI; r(2) = 0.84, P < .01). The median AHI yielded by the SleepView was higher than that of PSG: 33.2 (interquartile range of 10.5-53.3) versus 19.2 (interquartile range of 5.2-53.6). The sensitivity and specificity of the SleepView for a PSG AHI of ≥ 5 were 80.28% and 95.45%, respectively, and the cutoff was 16.8. The area under the receiver operating curve for PSG AHIs of ≥ 5, > 15, and > 30 was 0.923, 0.924, and 0.979, respectively. When the AHI and oxygen desaturation index calculated by the SleepView were combined with waist circumference, the new predictive model showed a higher sensitivity of 92.96% and a specificity of 95.45% for a PSG AHI of ≥ 5, and the corresponding area under the receiver operating curve was 0.983.

CONCLUSIONS

The SleepView device exhibited acceptable diagnostic accuracy for OSA in the Chinese population, especially in the severe OSA group. A practical predictive model comprising waist circumference, AHI, and oxygen desaturation index obtained with the SleepView was highly effective for screening even mild OSA. This simple and practical device may serve as a useful tool to screen for OSA. Further studies are required to validate the diagnostic efficiency of the SleepView in the home environment and in different populations.

Electron and positron fluxes in primary cosmic rays measured with the alpha magnetic spectrometer on the international space station

Precision measurements by the Alpha Magnetic Spectrometer on the International Space Station of the primary cosmic-ray electron flux in the range 0.5 to 700 GeV and the positron flux in the range 0.5 to 500 GeV are presented. The electron flux and the positron flux each require a description beyond a single power-law spectrum. Both the electron flux and the positron flux change their behavior at ∼30  GeV but the fluxes are significantly different in their magnitude and energy dependence. Between 20 and 200 GeV the positron spectral index is significantly harder than the electron spectral index. The determination of the differing behavior of the spectral indices versus energy is a new observation and provides important information on the origins of cosmic-ray electrons and positrons.

High statistics measurement of the positron fraction in primary cosmic rays of 0.5-500 GeV with the alpha magnetic spectrometer on the international space station

A precision measurement by AMS of the positron fraction in primary cosmic rays in the energy range from 0.5 to 500 GeV based on 10.9 million positron and electron events is presented. This measurement extends the energy range of our previous observation and increases its precision. The new results show, for the first time, that above ∼200  GeV the positron fraction no longer exhibits an increase with energy.

Mechanical characterization of outer epidermal middle lamella of onion under tensile loading

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PREMISE OF THE STUDY

The cells in plant tissue are joined together by a distinct layer called the middle lamella (ML). Understanding the mechanical properties of the ML is crucial in studying how tissue-level mechanical properties emerge from the subcellular-level mechanical properties. However, the nanoscale size of the ML presents formidable challenges to its characterization as a separate layer. Consequently, the mechanical properties of the ML under tensile loading are as yet unknown.•

METHODS

Here, we characterize the ML from a subcellular sample excised from two adjacent cells and composed of two wall fragments and a single line of ML in between. Two techniques, cryotome sectioning and milling with a focused ion beam, were used to prepare ML samples, and tensile experiments were performed using microelectromechanical system (MEMS) tensile testing devices.•

KEY RESULTS

Our test results showed that even at a subcellular scale, the ML appears to be stronger than the wall fragments. There was also evidence that the ML attached at the corner of cells more strongly than at the rest of the contact area. The contribution of the additional ML contact area was estimated to be 40.6 MPa. Wall fragment samples containing an ML layer were also significantly stronger (p < 0.05) than the wall fragments without an ML layer.•

CONCLUSIONS

The tensile properties of the ML might not have a major impact on the tissue-scale mechanical properties. This conclusion calls for further study of the ML, including characterization under shear loading conditions and elucidation of the contributions of other extracellular parameters, such as cell size and shape, to the overall tissue-level mechanical response.

The novel miR-9500 regulates the proliferation and migration of human lung cancer cells by targeting Akt1

MicroRNAs have crucial roles in lung cancer cell development. They regulate cell growth, proliferation and migration by mediating the expression of tumor suppressor genes and oncogenes. We identified and characterized the novel miR-9500 in human lung cancer cells. The miR-9500 forms a stem-loop structure and is conserved in other mammals. The expression levels of miR-9500 were reduced in lung cancer cells and lung cancer tissues compared with normal tissues, as verified by TaqMan miRNA assays. It was confirmed that the putative target gene, Akt1, was directly suppressed by miR-9500, as demonstrated by a luciferase reporter assay. The miR-9500 significantly repressed the protein expression levels of Akt1, as demonstrated via western blot, but did not affect the corresponding mRNA levels. Akt1 has an important role in lung carcinogenesis, and depletion of Akt1 has been shown to have antiproliferative and anti-migratory effects in previous studies. In the current study, the overexpression of miR-9500 inhibited cell proliferation and the expression of cell cycle-related proteins. Likewise, the overexpression of miR-9500 impeded cell migration in human lung cancer cells. In an in vivo assay, miR-9500 significantly suppressed Fluc expression compared with NC and ASO-miR-9500, suggesting that cell proliferation was inhibited in nude mice. Likewise, miR-9500 repressed tumorigenesis and metastasis by targeting Akt1. These data indicate that miR-9500 might be applicable for lung cancer therapy.

Contributions of the mechanical properties of major structural polysaccharides to the stiffness of a cell wall network model

PREMISE OF THE STUDY

The molecular mechanisms regulating the expansive growth of the plant cell wall have yet to be fully understood. The recent development of a computational cell wall model allows quantitative examinations of hypothesized cell wall loosening mechanisms.

METHODS

Computational cell wall network (CWN) models were generated using cellulose microfibrils (CMFs), hemicelluloses (HCs), and their interactions (CMF-HC). For each component, a range of stiffness values, representing various situations hypothesized as potential cell-wall-loosening mechanisms, were used in the calculation of the overall stiffness of the computational CWN model. Thus, a critical mechanism of the loosening of the primary cell wall was investigated using a computational approach by modeling the molecular structure.

KEY RESULTS

The increase in the stiffness equivalent of the CMF-HC interaction results in an increase in the Young's modulus of the CWN. In the major growth direction, the CWN stiffness is most sensitive to the CMF-HC interaction (75%). HC stiffness contributes moderately (24%) to the change in the CWN stiffness, whereas the CMF contribution is marginal (1%). Minor growth direction exhibited a similar trend except that the contributions of CMFs and HCs are higher than for the major growth direction.

CONCLUSIONS

The stiffness of the CMF-HC interaction is the most critical mechanical component in altering stiffness of the CWN model, which supports the hypothesized mechanism of expansin's role in efficient loosening of the plant cell wall by disrupting HC binding to CMFs. The comparison to experiments suggests additional load-bearing mechanisms in CMF-HC interactions.

Structure and photoluminescence properties of a rare-earth free red-emitting Mn2+-activated KMgBO3

Abnormal strong absorptions are observed in a Mg-based host KMgBO₃ doped by single Mn²⁺ ions, which lead to a strong red emission band centered at 636 nm.

Changes in gut microbial populations, intestinal morphology, expression of tight junction proteins, and cytokine production between two pig breeds after challenge with Escherichia coli K88: a comparative study

This study hypothesized that the gut microbial populations, intestinal morphology, and cytokine production are differentially altered in 2 different pig breeds, namely, Chinese native Jinhua pigs and European Landrace pigs, after orally challenge with enterotoxigenic Escherichia coli (ETEC) K88. A total of 12 Jinhua pigs and 12 Landrace pigs were allocated to either the nonchallenged or the challenged groups (6 pigs per group). The challenged pigs were orally administered ETEC K88, and their nonchallenged counterparts were given sterile Luria-Bertani broth. Selected gut microbial populations, intestinal morphology, mRNA expression of tight junction proteins, and the levels of ileal cytokines and secretory immunoglobulin A (sIgA) production were measured in Jinhua and Landrace pigs. The results showed that the challenged Jinhua pigs exhibited a significantly (P < 0.05) lower incidence of diarrhea compared with their Landrace counterparts. The Escherichia coli (E.coli) population and the percentage of E. coli in the total bacteria population were increased in response to ETEC K88 challenge in both Jinhua and Landrace pigs. The challenged Landrace pigs shed more E. coli (P < 0.05) and had higher percentage of E. coli in the total bacteria population in the colon (P < 0.05) compared with their Jinhua counterparts. Both pig breeds tended to exhibit greater villous atrophy and crypt depth reduction in all of the intestinal segments with challenge. The expression of tight junction proteins decreased in response to ETEC K88 challenge in both pig breeds. The levels of the proinflammatory cytokines interferon (IFN)-γ, tumor necrosis factor-α, and IL-6 and the secretion of sIgA were positively altered whereas the levels of the anti-inflammatory cytokine IL-4 and transforming growth factor (TGF)-β were negatively altered by ETEC K88 challenge in both breeds. Jinhua pigs exhibited significantly higher levels of IFN-γ and TGF-β (P < 0.05) in the challenged group. Our findings provide valuable evidence to explain the differences in the intestinal physiology between Jinhua and Landrace pigs; that is, Jinhua pigs appeared to show better growth performance, a lower incidence of diarrhea, and a lower extent of immune activation in response to ETEC K88 challenge and a higher Lactobacillus population, a higher percentage of Lactobacillus in the total bacteria population, a higher ratio of Lactobacillus to E. coli, and higher levels of tight junction proteins with and without challenge.