1,821 research outputs found
Dynamics in direct two-photon transition by frequency combs
Two-photon resonance transition technology has been proven to have a wide
range of applications,it's limited by the available wavelength of commercial
lasers.The application of optical comb technology with direct two-photon
transition (DTPT) will not be restricted by cw lasers.This article will further
theoretically analyze the dynamics effects of the DTPT process driven by
optical frequency combs. In a three-level atomic system, the population of
particles and the amount of momentum transfer on atoms are increased compared
to that of the DTPT-free process. The 17% of population increasement in 6-level
system of cesium atoms has verified that DTPT process has a robust enhancement
on the effect of momentum transfer. It can be used to excite the DTPTs of
rubidium and cesium simultaneously with the same mode-locked laser. And this
technology has potential applications in cooling different atoms to obtain
polar cold molecules, as well as high-precision spectroscopy measurement.Comment: 7 pages, 7 figure
Serum 25-hydroxyvitamin D levels and the risk of idiopathic central precocious puberty in girls
Introduction: Prior studies have found inconsistent results regarding the relationship between vitamin D status and Idiopathic Central Precocious Puberty (ICPP).
Objective: To assess the role of serum 25-hydroxyvitamin D (25 [OH]D) levels in ICPP development.
Method: The authors retrospectively collected data from 221 girls with ICPP and 144 healthy girls between January 2017 and December 2019. The participants’ serum 25(OH)D levels were measured using an automatic chemiluminescence method, and the association between serum 25(OH)D levels and the risk of ICPP was assessed using multivariate logistic regression analysis. Odds Ratios (OR) with 95% Confidence Intervals (95% CI) were calculated as effect estimates.
Results: Serum 25(OH)D levels in the ICPP group were significantly lower than those in healthy controls (p < 0.001). Multivariate analysis indicated that girls with insufficient vitamin D levels (OR = 0.201; 95% CI 0.094–0.428; p < 0.001) and sufficient vitamin D levels (OR = 0.141; 95% CI 0.053–0.375; p < 0.001) both had a lower risk of ICPP than girls with vitamin D deficiency. Moreover, the authors found that the height (p = 0.014), weight (p = 0.014), breast stage (p = 0.010), mother's height (p < 0.001), and luteinizing hormone/follicle-stimulating hormone ratio (p = 0.010) in girls with ICPP could be associated with levels of vitamin D.
Conclusion: This study found that a low serum 25(OH)D level is an independent risk factor for ICPP, and several characteristics of girls with ICPP could be affected by their vitamin D status.
A Study of the Merger History of the Galaxy Group HCG 62 Based on X-Ray Observations and SPH Simulations
We choose the bright compact group HCG 62, which was found to exhibit both
excess X-ray emission and high Fe abundance to the southwest of its core, as an
example to study the impact of mergers on chemical enrichment in the intragroup
medium. We first reanalyze the high-quality Chandra and XMM-Newton archive data
to search for the evidence for additional SN II yields, which is expected as a
direct result of the possible merger-induced starburst. We reveal that, similar
to the Fe abundance, the Mg abundance also shows a high value in both the
innermost region and the southwest substructure, forming a high-abundance
plateau, meanwhile all the SN Ia and SN II yields show rather flat
distributions in in favor of an early enrichment. Then we carry
out a series of idealized numerical simulations to model the collision of two
initially isolated galaxy groups by using the TreePM-SPH GADGET-3 code. We find
that the observed X-ray emission and metal distributions, as well as the
relative positions of the two bright central galaxies with reference to the
X-ray peak, can be well reproduced in a major merger with a mass ratio of 3
when the merger-induced starburst is assumed. The `best-match' snapshot is
pinpointed after the third pericentric passage when the southwest substructure
is formed due to gas sloshing. By following the evolution of the simulated
merging system, we conclude that the effects of such a major merger on chemical
enrichment are mostly restricted within the core region when the final relaxed
state is reached.Comment: Accepted for publication in the Astrophysical Journa
Brain derived neurotrophic factor (BDNF) contributes to the pain hypersensitivity following surgical incision in the rats
<p>Abstract</p> <p>Background</p> <p>The pathogenic role of brain derived neurotrophic factor (BDNF) in the incisional pain is poorly understood. The present study explores the role of the BDNF in the incision-induced pain hypersensitivity.</p> <p>Methods</p> <p>A longitudinal incision was made in one plantar hind paw of isoflurane-anesthetized rats. Dorsal root ganglias (DRG) and spinal cords were removed at various postoperative times (1–72 h). Expression pattern of BDNF was determined by immunohistochemistry and double-labeling immunofluorescence. Lidocaine-induced blockade of sciatic nerve function was used to determine the importance of afferent nerve activity on BDNF expression in the DRG and spinal cord after incision. BDNF antibody was administered intrathecally (IT) or intraperitoneal (IP) to modulate the spinal BDNF or peripheral BDNF after incision.</p> <p>Results</p> <p>After hind-paw incision, the BDNF was upregulated in the ipsilateral lumbar DRG and spinal cord whereas thoracic BDNF remained unchanged in response to incision. The upregulated BDNF was mainly expressed in the large-sized neurons in DRG and the neurons and the primary nerve terminals in the spinal cord. Sciatic nerve blockade prevented the increase of BDNF in the DRG and spinal cord. IT injection of BDNF antibody greatly inhibited the mechanical allodynia induced by incision whereas IP administration had only marginal effect.</p> <p>Conclusion</p> <p>The present study showed that incision induced the segmental upregulation of BDNF in the DRG and spinal cord through somatic afferent nerve transmission, and the upregulated BDNF contributed to the pain hypersensitivity induced by surgical incision.</p
Separation and economic recovery of strontium from Nanyishan oil-field water, China
The mass ratio of Ca to Sr is greater than 10 in Nanyishan oil-field water, which causes significant problems during the economic extraction and recovery of selected trace elements in the oil-field water. The oilfield water was isothermally evaporated and various salts such as Li, K, Mg, Ca, Na, Sr, Rb, Cs, Br, and I were obtained from the solution. The Sr content of each phase was determined by ICP-AES, the Sr distribution rule in this process was obtained, and the best separation stage for Sr was identified, to optimize the separation of Sr from Nanyishan oil-field water
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Cognitive-enhancing effects of polygalasaponin hydrolysate in aβ(25-35)-induced amnesic mice.
Polygalasaponins are the major active constituents of Polygala tenuifolia exhibiting antiamnesic activity, but their applications are limited due to their toxicities. Evidence showed that the toxicities can be attenuated by hydrolysis. Herein, effects of a hydrolysate of polygalasaponins (HPS) on cognitive impairment induced by Aβ(25-35) were assessed by Morris water maze and step-through passive avoidance tests. The impaired spatial reference memory was improved by HPS (50 and 100 mg/kg). In the acquisition trial of step-through test, HPS (50 and 100 mg/kg) increased the latency into the dark chamber and decreased the error frequency significantly (P < .05). However, no significant change was observed during the retention trial. Additionally, HPS increased the corresponding SOD activities (62.34%, 22.09%) and decreased MDA levels (28.21%, 32.35%) in both cortex and hippocampus as compared to model animals. These results show that HPS may be a useful treatment against amnesia probably via its antioxidant properties.Peer Reviewe
Cognitive-enhancing effects of polygalasaponin hydrolysate in aβ(25-35)-induced amnesic mice.
Polygalasaponins are the major active constituents of Polygala tenuifolia exhibiting antiamnesic activity, but their applications are limited due to their toxicities. Evidence showed that the toxicities can be attenuated by hydrolysis. Herein, effects of a hydrolysate of polygalasaponins (HPS) on cognitive impairment induced by Aβ25−35 were assessed by Morris water maze and step-through passive avoidance tests. The impaired spatial reference memory was improved by HPS (50 and 100mg/kg). In the acquisition trial of step-through test, HPS (50 and 100mg/kg) increased the latency into the dark chamber and decreased the error frequency significantly (P < .05). However, no significant change was observed during the retention trial. Additionally, HPS increased the corresponding SOD activities (62.34%, 22.09%) and decreased MDA levels (28.21%, 32.35%) in both cortex and hippocampus as compared to model animals. These results show that HPS may be a useful treatment against amnesia probably via its antioxidant properties
Construction of Drug Screening Cell Model and Application to New Compounds Interfering Production and Accumulation of Beta-Amyloid by Inhibiting Gamma-Secretase
ADP-ribosylation factor-like 4C (ARL4C), a novel ovarian cancer metastasis suppressor, identified by integrated genomics
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