3,574 research outputs found
Initial carrier-envelope phase of few-cycle pulses determined by THz emission from air plasma
The evolution of THz waveform generated in air plasma provides a sensitive
probe to the variation of the carrier envelope phase (CEP) of propagating
intense few-cycle pulses. Our experimental observation and calculation reveal
that the number and positions of the inversion of THz waveform are dependent on
the initial CEP, which is near 0.5{\pi} constantly under varied input pulse
energies when two inversions of THz waveform in air plasma become one. This
provides a method of measuring the initial CEP in an accuracy that is only
limited by the stability of the driving few-cycle pulses.Comment: 13 pages, 4 figure
Waveform-Controlled Terahertz Radiation from the Air Filament Produced by Few-Cycle Laser Pulses
Waveform-controlled Terahertz (THz) radiation is of great importance due to
its potential application in THz sensing and coherent control of quantum
systems. We demonstrated a novel scheme to generate waveform-controlled THz
radiation from air plasma produced when carrier-envelope-phase (CEP) stabilized
few-cycle laser pulses undergo filamentation in ambient air. We launched
CEP-stabilized 10 fs-long (~ 1.7 optical cycles) laser pulses at 1.8 {\mu}m
into air and found that the generated THz waveform can be controlled by varying
the filament length and the CEP of driving laser pulses. Calculations using the
photocurrent model and including the propagation effects well reproduce the
experimental results, and the origins of various phase shifts in the filament
are elucidated.Comment: 5pages, 5 figure
NGX6 gene mediated by promoter methylation as a potential molecular marker in colorectal cancer
<p>Abstract</p> <p>Background</p> <p>Nasopharyngeal carcinoma associated gene 6 (NGX6) is down-regulated in most colon cancer cell lines and tumor tissues when compared with their normal tissue samples. As a novel suppress tumor gene, it could inhibit colon cancer cell growth and cell cycle progression. However, little is known about the transcriptional mechanisms controlling NGX6 gene expression. Recent findings suggest that epigenetic inactivation of multiple tumor suppressor genes plays an important role in the tumorigenesis of colorectal carcinoma (CRC). In this study, we explored the role of DNA methylation in regulation of NGX6 transcription.</p> <p>Methods</p> <p>In the present study, we cloned the NGX6 promoter with characteristics of a CpG island by luciferase reporter assay. Then, the CpG methylation status around the NGX6 promoter region in colon cancer cell lines and colorectal tumor tissues was examined by methylation-specific PCR and bisulfite DNA sequencing. Finally, 5-Aza-2'-deoxycytidine (5-Aza-dC) treatment was used to confirm the correlation between NGX6 promoter methylation and its gene inactivation.</p> <p>Results</p> <p>The sequence spanning positions -157 to +276 was identified as the NGX6 promoter, in which no canonical TATA boxes were found, while two CAAT boxes and GC boxes were discovered. Methylation status was observed more frequently in 40 colorectal cancer samples than in 40 adjacent normal mucosa samples (18/40 versus 7/40; P < 0.05). An analysis correlating gene methylation status with clinicopathological cancer features revealed that dense methylation of the NGX6 promoter was associated with colorectal cancer patients age (P < 0.05). Moreover, a trend was shown toward metastasis status and primary site in colorectal carcinomas with NGX6 promoter methylation (p = 0.056 and P = 0.067, respectively). In addition, 5-Aza-dC could induce NGX6 mRNA expression and NGX6 promoter demethylation in HT-29 cells.</p> <p>Conclusions</p> <p>Down-regulation of NGX6 gene is related to the promoter methylation. DNA methylation of NGX6 promoter might be a potential molecular marker for diagnosis or prognosis, or serve as a therapeutic target.</p
对乙酰氨基酚中毒1例的抢救治疗和护理
Acetaminophen is commonly used for fever, joint pain, neuralgia, and migraine for its antipyretic and analgesic effects in clinical practice. While large dose of acetaminophen may result in toxic, which causes coma and respiratory failure, cardiac arrest and other organ damage. The paper discusses nursing methods of condition monitoring during continuous blood purification treatment, prevention of infection and nutritional support in patients with acetaminophen poisoning by case analysis.对乙酰胺基酚是临床常用的解热镇痛药,常用于发热、关节痛、神经痛和偏头痛的治疗,大剂量对乙酰胺基酚口服可引起中毒,导致昏迷、呼吸衰竭、心脏骤停等器官的损害。本文通过病例分析,探讨对乙酰氨基酚中毒患者行连续性血液净化治疗期间病情监测、预防感染、营养支持等护理方法
- …