Coherence of ion cyclotron resonance for damping ion cyclotron waves in space plasmas

Ion cyclotron resonance is one of the fundamental energy conversion processes through field-particle interaction in collisionless plasmas. However, the key evidence for ion cyclotron resonance (i.e., the coherence between electromagnetic fields and the ion phase space density) and the resulting damping of ion cyclotron waves (ICWs) has not yet been directly observed. Investigating the high-quality measurements of space plasmas by the Magnetospheric Multiscale (MMS) satellites, we find that both the wave electromagnetic field vectors and the bulk velocity of the disturbed ion velocity distribution rotate around the background magnetic field. Moreover, we find that the absolute gyro-phase angle difference between the center of the fluctuations in the ion velocity distribution functions and the wave electric field vectors falls in the range of (0, 90) degrees, consistent with the ongoing energy conversion from wave-fields to particles. By invoking plasma kinetic theory, we demonstrate that the field-particle correlation for the damping ion cyclotron waves in our theoretical model matches well with our observations. Furthermore, the wave electric field vectors ($\delta \mathbf{E'}_{\mathrm {wave,\perp}}$), the ion current density ($\delta \mathbf{J}_\mathrm {i,\perp}$) and the energy transfer rate ($\delta \mathbf{J}_\mathrm {i,\perp}\cdot \delta \mathbf{E'}_{\mathrm {wave,\perp}}$) exhibit quasi-periodic oscillations, and the integrated work done by the electromagnetic field on the ions are positive, indicates that ions are mainly energized by the perpendicular component of the electric field via cyclotron resonance. Therefore, our combined analysis of MMS observations and kinetic theory provides direct, thorough, and comprehensive evidence for ICW damping in space plasmas

Statistical Study of Anisotropic Proton Heating in Interplanetary Magnetic Switchbacks Measured by Parker Solar Probe

Magnetic switchbacks, which are large angular deflections of the interplanetary magnetic field, are frequently observed by Parker Solar Probe (PSP) in the inner heliosphere. Magnetic switchbacks are believed to play an important role in the heating of the solar corona and the solar wind as well as the acceleration of the solar wind in the inner heliosphere. Here, we analyze magnetic field data and plasma data measured by PSP during its second and fourth encounters, and select 71 switchback events with reversals of the radial component of the magnetic field at times of unchanged electron-strahl pitch angles. We investigate the anisotropic thermal kinetic properties of plasma during switchbacks in a statistical study of the measured proton temperatures in the parallel and perpendicular directions as well as proton density and specific proton fluid entropy. We apply the “genetic algorithm” method to directly fit the measured velocity distribution functions in field-aligned coordinates using a two-component bi-Maxwellian distribution function. We find that the protons in most switchback events are hotter than the ambient plasma outside the switchbacks, with characteristics of parallel and perpendicular heating. Specifically, significant parallel and perpendicular temperature increases are seen for 45 and 62 of the 71 events, respectively. We find that the density of most switchback events decreases rather than increases, which indicates that proton heating inside the switchbacks is not caused by adiabatic compression, but is probably generated by nonadiabatic heating caused by field–particle interactions. Accordingly, the proton fluid entropy is greater inside the switchbacks than in the ambient solar wind

Observations of rapidly growing whistler waves in front of space plasma shock

Whistler mode wave is a fundamental perturbation of electromagnetic fields and plasmas in various environments including planetary space, laboratory and astrophysics. The origin and evolution of the waves are a long-standing question due to the limited instrumental capability in resolving highly variable plasma and electromagnetic fields. Here, we analyse data with the high time resolution from the multi-scale magnetospheric spacecraft in the weak magnetic environment (i.e., foreshock) enabling a relatively long gyro-period of whistler mode wave. Moreover, we develop a novel approach to separate the three-dimensional fluctuating electron velocity distributions from their background, and have successfully captured the coherent resonance between electrons and electromagnetic fields at high frequency, providing the resultant growth rate of unstable whistler waves. Regarding the energy origin for the waves, the ion distributions are found to also play crucial roles in determining the eigenmode disturbances of fields and electrons. The quantification of wave growth rate can significantly advance the understandings of the wave evolution and the energy conversion with particles

Growth of hafnium dioxide thin films via metal-organic chemical vapor deposition

Metal-organic chemical vapour deposition (MOCVD) is a key technique for depositing thin solid film materials for use in important technological applications. To obtain thin films of the desired standard, it is essential to design volatile, reactive and thermally stable precursors. A metal-organic precursor consisting of Hf with excellent vaporization characteristics and low decomposition temperature has been reported. Hafnium dioxide thin films on a Mo substrate were obtained via thermal MOCVD using Hafnium(IV) acetylacetonate(Hf(acac) _4 ) in a horizontal cold-wall reactor. The Hf(acac) _4 precursor was synthesized from HfCl _4 and Hthd in methanol. Hf(acac) _4 was characterized using elemental analysis and infrared spectroscopy. The thermal decomposition properties were studied using thermogravimetric analysis under a nitrogen atmosphere. The results showed that Hf(acac) _4 was completely volatised at 245 °C. The thin films products were investigated using x-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The results from these measurements revealed that the main crystalline phase was the monoclinic phase, the surface consists of hafnium and oxygen and the morphology was densely packed and composed of visible grains

PAX1 and SEPT9 methylation analyses in cervical exfoliated cells are highly efficient for detecting cervical (pre)cancer in hrHPV-positive women

Studies have investigated PAX1 and SEPT methylation were closely associated with cervical cancer. For this study, we verified the expressions of PAX1 and SEPT9 methylation in 236 hrHPV women cervical exfoliated cells by using quantitative methylation-specific PCR and we further explored their diagnostic value in cervical (pre)cancer detection. Our results identified that the methylation rates and levels of PAX1 and SEPT9 increased with cervical lesion severity. For a diagnosis of cervical (pre)cancer, the area under the curve (AUC) of PAX1 methylation was 0.77 (95% CI 0.71–0.83) and the AUC of SEPT9 methylation was 0.86 (95% CI 0.81∼0.90). Analyses of the PAX1 and SEPT9 methylation statuses alone or combined with commonly used tests can efficiently identify cervical (pre)cancer. In particular, SEPT9 methylation might serve as an effective and powerful biomarker for the diagnosis of cervical (pre)cancer and as an alternative triage test in HPV-based cervical (pre)cancer screening programs.Impact Statement What is already known on this subject? This subject showed that PAX1 and SEPT9 methylation were closely associated with cervical cancer. The methylation rates and levels of PAX1 and SEPT9 increased with cervical lesion severity and reached a peak in cervical cancer exfoliated cells. We further assessed the diagnostic performances of PAX1 and SEPT9 methylation in cervical cancer screening. In detecting cervical (pre)cancer, the sensitivity values of PAX1 and SEPT9 methylation were up to 61.18% and 82.35%, respectively, and the specificity values of PAX1 and SEPT9 methylation were up to 95.36% and 86.75%, respectively. Moreover, the ROC curve analysis showed AUC values of 0.77 for PAX1 methylation and 0.86 for SEPT9 methylation tests, which were significantly superior to other commonly used tests. These findings suggest that PAX1 and SEPT9 methylation detection may have great clinical potential in cervical cancer screening. What the results of this study add? The rates and levels of PAX1 and SEPT9 methylation increased with the severity of the cervical lesions. For a diagnosis of cervical (pre)cancer, the area under the curve (AUC) of PAX1 methylation was 0.77 (95% CI 0.71–0.83), and the sensitivity and specificity values were 61.18% and 95.36%, respectively. The AUC value of the SEPT9 methylation was 0.86 (95% CI 0.81 ∼ 0.90), and the sensitivity and specificity values were 82.35% and 86.75%, respectively. Compared with the various tests we conducted, the PAX1 methylation showed the highest specificity (95.36%), and the SEPT9 methylation demonstrated the highest accuracy(86.00%). What the implications are of these findings for clinical practice and/or further research? The methylation levels of PAX1 and SEPT9 had a certain predictive effect on the severity of cervical lesions in hrHPV-positive women. In addition, SEPT9 methylation analysis performs better than PAX1 methylation analysis and commonly used tests in cervical exfoliated cells for detecting cervical (pre)cancer in hrHPV-positive women. SEPT9 methylation analysis merits consideration as an effective and objective, alternative triage test in HPV-based cervical (pre)cancer screening programs

The clinical significance of FAM19A4 methylation in high-risk HPV-positive cervical samples for the detection of cervical (pre)cancer in Chinese women

Abstract Background To explore the diagnostic value of FAM19A4 methylation in high-risk human papilloma virus (hrHPV)-positive cervical samples from Chinese women for estimating cervical cancer or its precancerous lesions. Methods Cervical samples from 215 women infected with high-risk HPV were collected by smear testing. We purposely chose 61 patients with cervical cancer, 57 with high-grade squamous intraepithelial lesions (HSIL), 31 with low-grade squamous intraepithelial lesions (LSIL), and 66 without cervical intraepithelial neoplasia (CIN) after histological confirmation. Taqman probe-based quantitative PCR (qPCR) was utilized to detect the methylation status of FAM19A4 in the cervical samples and further evaluate the use of this gene in the diagnosis of cervical cancer. Results (1) An increasing level of FAM19A4 methylation was detected with increasing progression of cervical lesions, with methylation rates of 10.61%(7/66), 35.48%(11/31), 56.14%(32/57) and 93.44%(57/61) in no CIN, LSIL, HSIL and cervical carcinoma samples respectively. (2) In all hrHPV-positive samples, the levels of FAM19A4 methylation in HPV16/18 groups were higher than that in 12 other hrHPV groups (P 0.05). (3)There were no significant differences of FAM19A4 methylation in different clinicopathological parameters of cervical cancer. (4) Though the sensitivity of FAM19A4 methylation test was inferior to that of cytology and FAM19A4 combining with HPV16/18 genotyping, but showed the best specificity with 81.44% both for detection HSIL alone and ≥ HSIL, with favorable youden index (YI) and area under curve (AUC). Conclusion FAM19A4 is a specific biomarker of cancerous lesions of the cervix. FAM19A4 methylation analysis may serve as an auxiliary screening method for diagnosis of cervical (pre)cancer. However, in consideration of the limitations of this retrospective study, prospective population-based studies are necessary for further confirmation of the diagnostic value of FAM19A4 methylation for detection of cervical (pre)cancer in Chinese women

Observations of Rapidly Growing Whistler Waves in Front of Space Plasma Shock due to Resonance Interaction between Fluctuating Electron Velocity Distributions and Electromagnetic Fields

The whistler-mode wave extending from the fast-magnetosonic wave branch is a fundamental perturbation of electromagnetic fields and plasmas in various environments including planetary space, laboratory, and astrophysics. The origin and evolution of the waves is a long-standing question due to the limited instrumental capability in resolving highly variable plasma and electromagnetic fields. Here, we analyze observational data with a high time resolution from the Magnetospheric Multiscale spacecraft in front of the terrestrial bow shock (e.g., foreshock). We develop a novel approach to extract the three-dimensional fluctuating electron velocity distributions (delta f (e)( V )) from their background (f (e0)( V )), and have successfully captured the coherent resonance between fluctuating electrons (delta f (e)( V )) and wavelike electromagnetic fields (delta B , delta E ) at an unprecedentedly high frequency (>1 Hz) for investigating wave-particle interactions. We provide that the unstable whistler wave grows rapidly over a timescale that is much shorter than the proton gyro-period. Regarding the energy origin for the waves, we find the ion distributions consisting of the solar wind ion flows and the ion beams reflected from the shock play crucial roles in providing the free energy and determining the eigenmode disturbances of fields and electrons. The quantification of wave growth rate and the characterization of wave-particle interactions for the instability driver can significantly advance the understandings of wave evolution and energy conversion between multisource multispecies particles and wave electromagnetic fields

Septin9 DNA methylation as a promising biomarker for cervical cancer

Aberrant Septin9 methylation in cervical cancer has been rarely studied. We aimed to identify its diagnostic value in cervical cancer using cervical scrapings, and its predictive potential in plasma for pelvic nodal metastasis of cervical cancer. The statuses of methylated Septin9 in fresh cervical lesions and cervical scrapings were first evaluated by using quantitative methylation-specific PCR. Subsequently, the relationship between Septin9 methylation in 113 plasma samples and pelvic nodal metastasis of cervical cancer was evaluated. Methylated Septin9 was detected in all cancerous tissues, but not in cervicitis. The degrees of Septin9 methylation increased with growing severity of cervical lesions in cervical scrapings. The sensitivity of methylated Septin9 was lower than that of cytology, while it yielded a high specificity and area under the curve in detecting high-grade squamous intraepithelial lesion or cervical cancer; and when Septin9 methylation combined with HPV16/18 genotyping, the sensitivity would increase from 70.42% to 82.39%. Plasma-based Septin9 methylation had a high discriminatory power in predicting pelvic nodal metastasis of cervical cancer, with an optimal specificity of 81.48%. In conclusion, we demonstrated methylated Septin9 to be an innovative diagnostic biomarker for cervical cancer and its non-invasive predictive potential in plasma for pelvic nodal metastasis of cervical cancer. Impact statementWhat is already known on this subject? The occurrence of cervical cancer is related to Septin9 methylation. In fresh specimens and cervical scrapings, we found the degrees of methylated Septin9 increased with growing severity of cervical lesions. Compared with HPV16/18 genotyping and cytological detection, Septin9 methylation had a better specificity and AUC in detecting ≥ HSIL. Furthermore, plasma-based Septin9 methylation also had a high specificity for pelvic lymphatic metastasis prediction.What the results of this study add? Methylation analysis of Septin9 indicated a similar sensitivity, specificity and AUC in detecting ≥ HSIL, relative to HPV16/18 genotyping. Compared with cytological method, Septin9 methylation also yielded a higher specificity and AUC in detecting ≥ HSIL. And we also found plasma-based Septin9 methylation had a high discriminatory power in predicting pelvic nodal metastasis of cervical cancer, with an optimal specificity of 81.48%; additionally an increasing sensitivity from 50% to nearly 80% was found when combined with SCCAg.What the implications are of these findings for clinical practice and/or further research? This study aimed to evaluate the relationship between Septin9 methylation and cervical cancer, and to explore the value of methylated Septin9 in the detection of cervical (pre)cancerous lesions. Moreover, we would explore plasma-based ctDNA biomarkers for pelvic lymphatic metastasis prediction of cervical cancer, to improve non-invasive predictive accuracy of pelvic nodal metastasis and reduce the complications caused by pelvic lymphadenectomy. What is already known on this subject? The occurrence of cervical cancer is related to Septin9 methylation. In fresh specimens and cervical scrapings, we found the degrees of methylated Septin9 increased with growing severity of cervical lesions. Compared with HPV16/18 genotyping and cytological detection, Septin9 methylation had a better specificity and AUC in detecting ≥ HSIL. Furthermore, plasma-based Septin9 methylation also had a high specificity for pelvic lymphatic metastasis prediction. What the results of this study add? Methylation analysis of Septin9 indicated a similar sensitivity, specificity and AUC in detecting ≥ HSIL, relative to HPV16/18 genotyping. Compared with cytological method, Septin9 methylation also yielded a higher specificity and AUC in detecting ≥ HSIL. And we also found plasma-based Septin9 methylation had a high discriminatory power in predicting pelvic nodal metastasis of cervical cancer, with an optimal specificity of 81.48%; additionally an increasing sensitivity from 50% to nearly 80% was found when combined with SCCAg. What the implications are of these findings for clinical practice and/or further research? This study aimed to evaluate the relationship between Septin9 methylation and cervical cancer, and to explore the value of methylated Septin9 in the detection of cervical (pre)cancerous lesions. Moreover, we would explore plasma-based ctDNA biomarkers for pelvic lymphatic metastasis prediction of cervical cancer, to improve non-invasive predictive accuracy of pelvic nodal metastasis and reduce the complications caused by pelvic lymphadenectomy.</p