Energetic electron depletions are a notable feature of the nightside Martian upper atmosphere. In this study, we investigate systematically the variations of the occurrence of depletions with both ...internal and external conditions, using the extensive Solar Wind Electron Analyzer measurements made on board the Mars Atmosphere and Volatile Evolution. In addition to the known trends of increasing occurrence with decreasing altitude and increasing magnetic field intensity, our analysis reveals that depletions are more easily observed in regions with near horizontal magnetic fields and under low solar wind (SW) dynamic pressures. We also find that below 160 km, the occurrence increases with increasing CO2 density, a trend mostly visible in weakly magnetized regions. These observations have important implications on the formation of electron depletions: (1) Near strong magnetic anomalies, closed magnetic loops preferentially form and shield the atmosphere from direct access of SW electrons, a process that is modulated by the upstream SW condition; and (2) in weakly magnetized regions, SW electrons precipitate into the atmosphere unhindered, but at sufficiently low altitudes, they are either “absorbed” due to inelastic collisions with ambient neutrals or shielded again in response to a change in magnetic connectivity from open to closed. Our analysis further reveals that both the ionospheric plasma content and thermal electron temperature are reduced in regions with depletions compared to regions without, supporting SW electron precipitation as an important source of external energy driving the variability in the deep nightside Martian upper atmosphere and ionosphere.
Key Points
Electron depletions in the nightside Martian ionosphere are more easily observed in regions with near horizontal magnetic fields
Electron depletions are more easily observed under low solar wind dynamic pressures
Substantially reduced ionospheric plasma content and thermal electron temperature are observed in regions with depletions
Background and purpose
Restless legs syndrome (RLS) is an underestimated movement disorder in patients with end‐stage renal disease (ESRD). Several clinical and laboratory factors were inconsistently ...reported to associate with RLS. We aim to perform a large‐scale multicenter study to investigate the possible associated risk factors of RLS in patients with ESRD in Taiwan, a country with the highest incidence of uremia in the world.
Methods
From October 2009 to October 2011, we constitutively recruited 1130 patients with ESRD from 17 hemodialysis centers. Demographic, laboratory data, presence and severity of RLS were collected. Odds ratios (ORs) were estimated by logistic regression models.
Results
We found the prevalence of RLS to be 25.3% in patients with ESRD. Having type 2 diabetes OR = 3.61 (2.27–5.77), P < 0.01, low serum transferrin saturation OR = 1.42 (1.01–2.03), P < 0.05 and duration of dialysis OR = 1.09 (1.03–1.14), P < 0.01 were associated with RLS. In contrast, high serum hemoglobin level was inversely associated with RLS OR = 0.61 (0.40–0.89), P < 0.05. RLS has a significant impact on sleep quality in dialysis patients. Among patients with RLS, history of type 2 diabetes OR = 4.04 (1.65–10.79), P < 0.05, low serum hemoglobin level OR = 5.41 (2.43–13.12), P < 0.01 and duration of dialysis OR = 1.01 (1.01–1.02), P < 0.01 were associated with increased severity of RLS.
Conclusions
Our findings demonstrated that RLS is common in Taiwanese dialysis patients. Clinicians should have a high suspicion for the presence of RLS symptoms in patients with ESRD, especially those with type 2 diabetes, anemia, low serum iron status and long duration of dialysis.
Abstract
We present a study of the efficiency of the acceleration of suprathermal electrons at collisionless shock waves driven by interplanetary coronal mass ejections (ICMEs), with the data ...analysis from both the spacecraft observations and test-particle simulations. The observations are from the 3DP/EESA instrument on board Wind during the 74 shock events listed in Yang et al., and the test-particle simulations are carried out through 315 cases with different shock parameters. A total of seven energy channels ranging from 0.428–4.161 keV are selected. In the simulations, using a backward-in-time method, we calculate the average downstream flux in the 90° pitch angle. On the other hand, the average downstream and upstream fluxes in the 90° pitch angle can also be directly obtained from the 74 observational shock events. In addition, the variation in the event number ratio with the downstream to upstream flux ratio above a threshold value in terms of the shock angle (the angle between the shock normal and upstream magnetic field), upstream Alfvén Mach number, and shock compression ratio is statistically obtained. It is shown from both the observations and simulations that a large shock angle, upstream Alfvén Mach number, and shock compression ratio can enhance the efficiency of the shock acceleration. Our results suggest that shock drift acceleration is more efficient in the electron acceleration by ICME-driven shocks, which confirms the findings of Yang et al.
Ground-level enhancements generally accompany fast interplanetary coronal mass ejections (ICMEs), and ICME-driven shocks are sources of solar energetic particles (SEPs). Observations of the GLE event ...of 2000 July 14 show that a very fast and strong magnetic cloud (MC) is behind the ICME shock and the proton intensity-time profiles observed at 1 au had a rapid two-step decrease near the sheath and MC. Therefore, we study the effect of sheath and MC on SEPs accelerated by an ICME shock by numerically solving the focused transport equation. The shock is regarded as a moving source of SEPs with an assumed particle distribution function. The sheath and MC are set to thick spherical caps with enhanced magnetic field, and the turbulence levels in the sheath and MC are set to be higher and lower than those of the ambient solar wind, respectively. The simulation results of proton intensity-time profiles agree well with the observations in energies ranging from ∼1 to ∼100 MeV, and the two-step decrease is reproduced when the sheath and MC arrived at the Earth. The simulation results show that the sheath-MC structure reduced the proton intensities for about 2 days after the shock passed through the Earth. It is found that the sheath contributed most of the decrease while the MC facilitated the formation of the second step decrease. The simulation also infers that the coordination of magnetic field and turbulence in sheath-MC structure can produce a stronger reduction of SEP intensities.
Tantalum arsenide is a member of the noncentrosymmetric monopnictides, which are putative Weyl semimetals. In these materials, three-dimensional chiral massless quasiparticles, the so-called Weyl ...fermions, are predicted to induce novel quantum mechanical phenomena, such as the chiral anomaly and topological surface states. However, their chirality is only well defined if the Fermi level is close enough to the Weyl points that separate Fermi surface pockets of opposite chirality exist. In this Letter, we present the bulk Fermi surface topology of high quality single crystals of TaAs, as determined by angle-dependent Shubnikov-de Haas and de Haas-van Alphen measurements combined with ab initio band-structure calculations. Quantum oscillations originating from three different types of Fermi surface pockets were found in magnetization, magnetic torque, and magnetoresistance measurements performed in magnetic fields up to 14 T and temperatures down to 1.8 K. Of these Fermi pockets, two are pairs of topologically nontrivial electron pockets around the Weyl points and one is a trivial hole pocket. Unlike the other members of the noncentrosymmetric monopnictides, TaAs is the first Weyl semimetal candidate with the Fermi energy sufficiently close to both types of Weyl points to generate chiral quasiparticles at the Fermi surface.
Background
Dementia is an irreversible illness. The caregiver is expected to assume increased responsibility as the condition of the person with dementia declines. It is important to explore the ...factors constituting caregiver burden on the informal caregivers of people with dementia.
Aims
The purpose of this article is to identify the factors constituting caregiver burden on the informal caregivers of people with dementia living in the community.
Methods
A systematic review of the four databases, including PubMed, PsycINFO, CINAHL and the Cochrane Library, was carried out to access relevant articles published between 2003 and 2012. Twenty‐one articles met the inclusion criteria of this study.
Results
Behavioural problems or psychological symptoms were the primary factor of the person with dementia that is associated with caregiver burden. Caregiver socio‐demographical factors and psychological factors were the two primary factors of the caregiver burden.
Limitations
Several results of this study were based on studies that had their own limitations. Furthermore, the concept of caregiver ‘burden’ was not clearly defined in some of the studies; instead, the term was broadly defined.
Conclusion
Factors of caregiver burden in regard to people with dementia living in the community were clarified in this review study. By identifying all of the factors, healthcare professionals can deliver appropriate assistance to relieve caregiver burden and improve the quality of caregiving for people with dementia.
Implications for Nursing and Health Policy
It is important to identify the factors of the burden on the caregivers of people with dementia living in the community to prevent early nursing home placement, deterioration of caregiver's health and reduce the adverse health outcomes for care recipients. A health‐related policy should be formulated to help informal caregivers receive more professional assistance. Training opportunities should be provided for family caregivers to reduce the impact of caregiving on the delivery of effective care.
Solar cycles are studied with the Version 2 monthly smoothed international sunspot number, the variations of which are found to be well represented by a modified logistic differential equation with ...four parameters: maximum cumulative sunspot number or total sunspot number xm, initial cumulative sunspot number x0, maximum emergence rate r0, and asymmetry . A two-parameter function is obtained by taking and r0 as fixed values. In addition, it is found that xm and x0 can be well determined at the start of a cycle. Therefore, a predictive model of sunspot number is established based on the two-parameter function. The prediction for cycles 4-23 shows that the solar maximum can be predicted with an average relative error of 8.8% and maximum relative error of 22% in cycle 15 at the start of solar cycles if solar minima are already known. The quasi-online method for determining the moment of solar minimum shows that we can obtain the solar minimum 14 months after the start of a cycle. Besides, our model can predict the cycle length with an average relative error of 9.5% and maximum relative error of 22% in cycle 4. Furthermore, we predict the variations in sunspot number of cycle 24 with the relative errors of the solar maximum and ascent time being 1.4% and 12%, respectively, and the predicted cycle length is 11.0 yr (95% confidence interval is 8.3-12.9 yr). A comparison to the observations of cycle 24 shows that our predictive model has good effectiveness.
With continued climate changes, soil drought stress has become the main limiting factor for crop growth in arid and semi‐arid regions. A typical characteristic of drought stress is the burst of ...reactive oxygen species (ROS), causing oxidative damage. Plant‐associated microbes, such as arbuscular mycorrhizal fungi (AMF), can regulate physiological and molecular responses to tolerate drought stress, and they have a strong ability to cope with drought‐induced oxidative damage via enhanced antioxidant defence systems. AMF produce a limited oxidative burst in the arbuscule‐containing root cortical cells. Similar to plants, AMF modulate a fungal network in enzymatic (e.g. GmarCuZnSOD and GintSOD1) and non‐enzymatic (e.g. GintMT1, GinPDX1 and GintGRX1) antioxidant defence systems to scavenge ROS. Plants also respond to mycorrhization to enhance stress tolerance via metabolites and the induction of genes. The present review provides an overview of the network of plant − arbuscular mycorrhizal fungus dialogue in mitigating oxidative stress. Future studies should involve identifying genes and transcription factors from both AMF and host plants in response to drought stress, and utilize transcriptomics, proteomics and metabolomics to clarify a clear dialogue mechanism between plants and AMF in mitigating oxidative burst.
The dialogue of arbuscular mycorrhizal fungi and host plants confers a mitigating drought‐induced oxidative burst in hosts.
Global dust storms (GDS) are an important dynamical phenomenon of the Martian lower atmosphere but are known to have important impacts on the Martian middle/upper atmosphere and ionosphere. Despite ...extensive studies over the past several decades, how the composition of the Martian ionosphere is modified during the GDS has only been studied from a theoretical point of view. Here we present for the first time the observations of the compositional variation of the Martian ionosphere during the GDS in 2018, using the ion density measurements made by the Neutral Gas and Ion Mass Spectrometer onboard the Mars Atmosphere and Volatile Evolution. At a representative altitude of 170 km, the variations of ionospheric species during the GDS show either enhancement (CO2+, Ar+, HO2+, H2O+, H2+, ArH+) or depletion (O2+, O+, N2+/CO+, OH+). Despite the apparent diversity, the observations are mostly understandable within the established framework of ionospheric chemistry on Mars, which further demonstrates that the variation of ion species during the GDS is a good diagnostic of the variation of relevant neutral species in the thermosphere. In particular, the observed ionospheric variation strongly supports a scenario that H2O is substantially enhanced in the Martian thermosphere during the GDS. However, the variations of O2+ and H2+ are inconsistent with predictions from ionospheric chemistry and require further investigation.
Plain Language Summary
Global dust storms (GDS) are an important dynamical phenomenon of the Martian climate that has been extensively studied over the past several decades. Though occurring in the lower atmosphere, they are known to have important impacts on the upper atmosphere and ionosphere, such as increasing the thermospheric water content, enhancing hydrogen escape, and lifting the ionospheric layer. Despite the existing efforts, how the composition of the Martian ionosphere is modified by has not been well studied. Owing to the accumulation of the ion density measurements made onboard the Mars Atmosphere and Volatile Evolution and the dust opacity measurements made onboard the Mars Reconnaissance Orbiter, we present for the first time a preliminary investigation of the species‐dependent variations of the dayside Martian ionosphere during the GDS in 2018. The responses of various ionospheric species to this event show diverse features, some demonstrating clear enhancement, whereas the others demonstrating clear depletion. Despite this, the observations are mostly consistent with the established ionospheric chemistry on Mars, implying that the variation of ionospheric species during a GDS is closely linked to the variation of neutral species in the thermosphere during the same event.
Key Points
Variations of the Martian ionosphere during global dust storms are species dependent, displaying either density enhancement or depletion
The variations of most ion species except for O2+ and H2+ are interpreted using the ionospheric chemistry on Mars
Substantial enhancement in thermospheric H2O on Mars during global dust storms are implied by ion measurements
Topological quantum materials represent a new class of matter with both exotic physical phenomena and novel application potentials. Many Heusler compounds, which exhibit rich emergent properties such ...as unusual magnetism, superconductivity and heavy fermion behaviour, have been predicted to host non-trivial topological electronic structures. The coexistence of topological order and other unusual properties makes Heusler materials ideal platform to search for new topological quantum phases (such as quantum anomalous Hall insulator and topological superconductor). By carrying out angle-resolved photoemission spectroscopy and ab initio calculations on rare-earth half-Heusler compounds LnPtBi (Ln=Lu, Y), we directly observe the unusual topological surface states on these materials, establishing them as first members with non-trivial topological electronic structure in this class of materials. Moreover, as LnPtBi compounds are non-centrosymmetric superconductors, our discovery further highlights them as promising candidates of topological superconductors.
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