1,330 research outputs found
IPS Observation System for Miyun 50m Radio Telescope and Its Acceptance Observation
Ground-based observation of Interplanetary Scintillation(IPS) is an important
approach of monitoring solar wind. A ground-based IPS observation system is
newly implemented on 50m radio telescope, Miyun station, National Astronomical
Observatories, Chinese Academy of Sciences(NAOC). This observation system is
constructed for purpose of observing the solar wind speed and scintillation
index by using the normalized cross-spectrum of simultaneous dual-frequency IPS
measurement. The system consists of a universal dual-frequency front-end and a
dual-channel multi-function back-end specially designed for IPS. After careful
calibration and testing, IPS observations on source 3C273B and 3C279 are
successfully carried out. The preliminary observation results show that this
newly developed observation system is capable of doing IPS observation.The
system sensitivity for IPS observation can reach over 0.3Jy in terms of IPS
polarization correlator with 4MHz bandwidth and 2s integration time.Comment: 8 pages, 7 figure
Spectral karyotyping reveals a comprehensive karyotype in an adult acute lymphoblastic leukemia
Cytogenetic abnormalities are frequently detected in patients with acute lymphoblastic leu-kemia (ALL). Comprehensive karyotype was related to poor prognosis frequently in ALL. We present a comprehensive karyotype in an adult ALL by spectral karyotyping (SKY) and R-banding. SKY not only confirmed the abnormalities previously seen by R-banding but also improved comprehensive karyotype analysis with the following result 47,XY,+9, ins(1;5)(q23;q23q34) t(6;7)(q23;p13). Our report demonstrated that SKY is able to provide more information accurately for prediction of disease prognosis in adult ALL with compre-hensive karyotype
The high helium abundance and charge states of the interplanetary CME and its material source on the Sun
Identifying the source of the material within coronal mass ejections (CMEs)
and understanding CME onset mechanisms are fundamental issues in solar and
space physics. Parameters relating to plasma composition, such as charge states
and He abundance (\ahe), may be different for plasmas originating from
differing processes or regions on the Sun. Thus, it is crucial to examine the
relationship between in-situ measurements of CME composition and activity on
the Sun. We study the CME that erupted on 2014 September 10, in association
with an X1.6 flare, by analyzing AIA imaging and IRIS spectroscopic
observations and its in-situ signatures detected by Wind and ACE. We find that
during the slow expansion and intensity increase of the sigmoid, plasma
temperatures of 9 MK, and higher, first appear at the footpoints of the
sigmoid, associated with chromospheric brightening. Then the high-temperature
region extends along the sigmoid. IRIS observations confirm that this extension
is caused by transportation of hot plasma upflow. Our results show that
chromospheric material can be heated to 9 MK, and above, by chromospheric
evaporation at the sigmoid footpoints before flare onset. The heated
chromospheric material can transport into the sigmoidal structure and supply
mass to the CME. The aforementioned CME mass supply scenario provides a
reasonable explanation for the detection of high charge states and elevated
\ahe\ in the associated ICME. The observations also demonstrate that the
quasi-steady evolution in the precursor phase is dominated by magnetic
reconnection between the rising flux rope and the overlying magnetic field
structure.Comment: 10 pages, 5 figures, accepted for publication in ApJ
Suppression of Hypoxia-Inducible Factor 1α (HIF-1α) by Tirapazamine Is Dependent on eIF2α Phosphorylation Rather Than the mTORC1/4E-BP1 Pathway
Hypoxia-inducible factor 1 (HIF-1), a heterodimeric transcription factor that mediates the adaptation of tumor cells and tissues to the hypoxic microenvironment, has attracted considerable interest as a potential therapeutic target. Tirapazamine (TPZ), a well-characterized bioreductive anticancer agent, is currently in Phase II and III clinical trials. A major aspect of the anticancer activity of TPZ is its identity as a tumor-specific topoisomerase IIα inhibitor. In the study, for the first time, we found that TPZ acts in a novel manner to inhibit HIF-1α accumulation driven by hypoxia or growth factors in human cancer cells and in HepG2 cell-derived tumors in athymic nude mice. We investigated the mechanism of TPZ on HIF-1α in HeLa human cervical cancer cells by western blot analysis, reverse transcription-PCR assay, luciferase reporter assay and small interfering RNA (siRNA) assay. Mechanistic studies demonstrated that neither HIF-1α mRNA levels nor HIF-1α protein degradation are affected by TPZ. However, TPZ was found to be involved in HIF-1α translational regulation. Further studies revealed that the inhibitory effect of TPZ on HIF-1α protein synthesis is dependent on the phosphorylation of translation initiation factor 2α (eIF2α) rather than the mTOR complex 1/eukaryotic initiation factor 4E-binding protein-1 (mTORC1/4E-BP1) pathway. Immunofluorescence analysis of tumor sections provide the in vivo evidences to support our hypothesis. Additionally, siRNA specifically targeting topoisomerase IIα did not reverse the ability of TPZ to inhibit HIF-1α expression, suggesting that the HIF-1α inhibitory activity of TPZ is independent of its topoisomerase IIα inhibition. In conclusion, our findings suggest that TPZ is a potent regulator of HIF-1α and provide new insight into the potential molecular mechanism whereby TPZ serves to reduce HIF-1α expression
Design and fabrication of a D 33 -mode piezoelectric micro-accelerometer
Abstract(#br)In this paper, a D 33 -mode piezoelectric micro-accelerometer with Pb 1.1 (Zr 0.52 Ti 0.48 )O 3 (PZT) thin film is designed, fabricated and tested. Both the polarization and deformation directions of the piezoelectric thin film are horizontal in this structure. With the high sensitivity and natural frequency, the D 33 -mode piezoelectric micro-accelerometer possesses improved practicality. The influence of filling factor ( Γ ) and interdigital electrode width ( b ) on the output voltage is analyzed in this work. The micro-electro-mechanical systems technology is then used to fabricate the piezoelectric accelerometer device, which is based on the Sol–Gel PZT piezoelectric thin film. Performance of the piezoelectric accelerometer micro-devices with the different Γ and b is..
- …