234 research outputs found
Chaotic to ordered state transition of cathode-sheath instabilities in DC glow discharge plasmas
Transition from chaotic to ordered state has been observed during the initial
stage of a discharge in a cylindrical dc glow discharge plasma. Initially it
shows a chaotic behavior but increasing the discharge voltage changes the
characteristics of the discharge glow and shows a period substraction of order
7 period 5 period 3 period 1 period i.e. the system goes to
single mode through odd cycle subtraction. On further increasing the discharge
voltage, the system goes through period doubling, like 1 period 2 period
4 period. On further increasing the voltage, the system goes to stable
state without having any oscillations.Comment: chathode-sheath, instabilities, chaos, period-subtraction,
bifurcation, dc-discharg
Monitoring global traveling ionospheric disturbances using the worldwide GPS network during the October 2003 storms
Urban Land Issues and Policy Challenges in China’s Rapid Urbanization
This paper discusses land issues and attempts to explain why they are persistent and prevalent in Chinese cities We will demonstrate that the factors behind the land issues include land institution setting gradualism in reforms illdesigned policy instruments one-size-fits-all approaches to land management a fragmented planning system and development objectives that are conflicting among themselves at the national level We then discuss land policy challenges and unfinished reforms that deserve attention Land reforms underscore the balancing act required between the concerns about the protection of property rights and public interests They were meant to address the entitlement question of unearned land value increments minimize social welfare losses in farmland protection and add planning policy flexibility to cope with future development uncertainty Finally we illustrate the challenges in policy choices and the importance of the political will determination of top leaders at all levels of government in undertaking radical and fundamental land policy reforms Political will determination would be critical in land policy reforms because leaders will face rising political resistance and huge socioeconomic cost
The Prognostic Significance of Beta2 Microglobulin in Patients with Hemophagocytic Lymphohistiocytosis
Objective. To determine the prognostic significance of beta2 microglobulin (β2-m) concentrations in patients with hemophagocytic lymphohistiocytosis (HLH), a rare disorder caused by pathologic activation of the immune system.Patients and Methods. The study population consisted of 74 patients diagnosed with HLH and 35 healthy controls. Serumβ2-m levels were measured using a latex agglutination photometric immunoassay.Results. Median serumβ2-m levels were significantly higher in HLH patients than in healthy controls (4.05 versus 1.5 mg/L;P<0.001) and were significantly higher in patients with lymphoma associated hemophagocytic syndrome (LAHS) than in patients with benign disease-associated HLH (4.2 versus 3.3 mg/L;P<0.001). Higher serumβ2-m levels were positively correlated with LAHS (P=0.005), abnormal lactate dehydrogenase concentrations (P=0.009), and hypoalbuminemia (P=0.003). ROC analysis showed that overall survival (OS) was significantly shorter in LAHS patients with serumβ2-m levels ≥4.03 mg/L compared to <4.03 mg/L (P<0.001). Moreover, multivariate analysis showed that serumβ2-m level was an independent prognostic of OS (P=0.034) in patients with LAHS.Conclusion. High serumβ2-m levels and LAHS were associated with markedly poorer OS in patients with HLH. Serumβ2-m concentration was a powerful and independent prognostic factor for OS in patients with LAHS.</jats:p
Impact of Bariatric Surgery on Ghrelin and Obestatin Levels in Obesity or Type 2 Diabetes Mellitus Rat Model
We aimed to evaluate the therapeutic efficacy on weight control by different bariatric surgeries and investigate the ghrelin and obestatin changes after these surgeries in obesity and nonobese type 2 diabetes mellitus (T2DM) rats. Obese rats were randomly assigned to receive sleeve gastrectomy (SG, n = 8), minigastric bypass (MGBP, n = 8), roux-en-Y gastric bypass (RYGBP, n = 8), and sham operation (SO, n = 4). Another 4 rats served as control. Besides, Goto-Kakisaki (GK) rats were also randomly divided into similar groups except for total gastrectomy (TG, n = 8) group. The results showed that in obese rats, weigh loss in RYGBP group was similar to that in MGBP group but larger than that in SG group. Ghrelin significantly increased in RYGB group, but obestatin increased in MGBP group. Ghrelin/obestatin ratio significantly decreased in SG group. In GK rats, weight loss was most obvious in TG group. Postoperatively, ghrelin was significantly increased in MGBP and RYGB groups but decreased in TG group. Obestatin also showed an increase in MGBP and RYGB groups. Ghrelin/obestatin in TG group decreased significantly. In conclusion, RYGB and MGBP may be more suitable for obese rats, but TG may be the best strategy for T2DM rats to control weight with different mechanisms
Parametrization of nonlinear and chaotic oscillations in driven beam-plasma diodes
Nonlinear phenomena in a driven plasma diode are studied using a fluid code and the particle-in-cell simulation code XPDPI. When a uniform electron beam is injected to a bounded diode filled with uniform ion background, the beam is destabilized by the Pierce instability and a perturbation grows to exhibit nonlinear oscillations including chaos. Two standard routes to chaos, period doubling and quasiperiodicity, are observed. Mode lockings of various winding numbers are observed in an ac driven system. A new diagnostic quantity is used to parametrize various nonlinear oscillations.open10
Extracellular vesicles derived from dental follicle stem cells regulate tooth eruption by inhibiting osteoclast differentiation
Tooth eruption as a crucial part in tooth development and regeneration is accompanied by ongoing osteogenesis and osteoclast activity. The dental follicle (DF) surrounding the developing tooth harbors dental follicle stem cells (DFSCs) which play a crucial role in maintaining bone remodeling. However, the mechanisms through which they regulate the balance between osteogenesis and osteoclast activity during tooth eruption remain poorly understood. Notably, extracellular vesicles (EVs) in bone homeostasis are considered essential. Our study revealed that the DFSCs could modulate tooth eruption by inhibiting osteoclast differentiation via EVs. Further investigation showed that EVs from DFSCs could inhibit osteoclast differentiation through the ANXA1-PPARγ-CEBPα pathway. Animal experiments indicated that EVs from DFSCs and the cargo ANXA1 affected tooth eruption. In summary, this study suggests the critical role of the dental follicle in tooth eruption through EVs, which may provide therapeutic targets for abnormal tooth eruption and effective approaches for the eruption of regenerated teeth
Effects of Magnetic Helicity on 3D Equilibria and Self-Organized States in KTX Reversed Field Pinch
The RFP is a toroidal magnetic configuration in which plasmas can
spontaneously transform into different self-organized states. Among various
states, the QSH state has a dominant component for the magnetic field and
significantly improves confinement. Many theoretical and experimental efforts
have investigated the transitions among different states. This paper employs
the MRxMHD model to study the properties of QSH and other states. The SPEC is
used to compute MHD equilibria for the KTX. The toroidal volume of KTX is
partitioned into two subvolumes by an internal transport barrier. The geometry
of this barrier is adjusted to achieve force balance across the interface,
ensuring that the plasma in each subvolume is force-free and that magnetic
helicity is conserved. By varying the parameters, we generate distinct
self-organized states in KTX. Our findings highlight the crucial role of
magnetic helicity in shaping these states. In states with low magnetic helicity
in both subvolumes, the plasma exhibits axisymmetric behavior. With increasing
core helicity, the plasma gradually transforms from an axisymmetric state to a
double-axis helical state and finally to a single-helical-axis state. Elevated
core magnetic helicity leads to a more pronounced dominant mode of the boundary
magnetic field and a reduced core magnetic shear. This is consistent with
previous experimental and numerical results in other RFP devices. We find a
linear relationship between the plasma current and helicity in different
self-organized states. Our findings suggest that KTX may enter the QSH state
when the toroidal current reaches 0.72 MA. This study demonstrates that the
stellarator equilibrium code SPEC unveils crucial RFP equilibrium properties,
rendering it applicable to a broad range of RFP devices and other toroidal
configurations
Reforestation in southern China: revisiting soil N mineralization and nitrification after 8 years restoration
Nitrogen availability and tree species selection play important roles in reforestation. However, long-term field studies on the effects and mechanisms of tree species composition on N transformation are very limited. Eight years after tree seedlings were planted in a field experiment, we revisited the site and tested how tree species composition affects the dynamics of N mineralization and nitrification. Both tree species composition and season significantly influenced the soil dissolved organic carbon (DOC) and nitrogen (DON). N-fixing Acacia crassicarpa monoculture had the highest DON, and 10-mixed species plantation had the highest DOC. The lowest DOC and DON concentrations were both observed in Eucalyptus urophylla monoculture. The tree species composition also significantly affected net N mineralization rates. The highest rate of net N mineralization was found in A. crassicarpa monoculture, which was over twice than that in Castanopsis hystrix monoculture. The annual net N mineralization rates of 10-mixed and 30-mixed plantations were similar as that of N-fixing monoculture. Since mixed plantations have good performance in increasing soil DOC, DON, N mineralization and plant biodiversity, we recommend that mixed species plantations should be used as a sustainable approach for the restoration of degraded land in southern China
Pathogenesis of depression and the potential for traditional Chinese medicine treatment
Depression is a prevalent mental disorder that significantly diminishes quality of life and longevity, ranking as one of the primary causes of disability globally. Contemporary research has explored the potential pathogenesis of depression from various angles, encompassing genetics, neurotransmitter systems, neurotrophic factors, the hypothalamic-pituitary-adrenal axis, inflammation, and intestinal flora, among other contributing factors. In addition, conventional chemical medications are plagued by delayed onset of action, persistent adverse effects, and restricted therapeutic efficacy. In light of these limitations, the therapeutic approach of traditional Chinese medicine (TCM) has gained increasing recognition for its superior effectiveness. Numerous pharmacological and clinical studies have substantiated TCM’s capacity to mitigate depressive symptoms through diverse mechanisms. This article attempts to summarize the mechanisms involved in the pathogenesis of depression and to describe the characteristics of herbal medicines (including compounded formulas and active ingredients) for the treatment of depression. It further evaluates their effectiveness by correlating with the multifaceted pathogenesis of depression, thereby furnishing a reference for future research endeavors
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