252 research outputs found
Vibration Isolation Of A Carbon Nanotube Filled With A Mass Chain
Vibration isolation is one of the most prominent characteristics of elastic metamaterial with negative effective mass. In this work, we show that a carbon nanotube filled with a linear mass chain can behave like an elastic metamaterial with negative effective mass density and exhibit remarkable vibration isolation phenomena within a certain frequency range
Surgical excision promotes tumor growth and metastasis by promoting expression of MMP-9 and VEGF in a breast cancer model
Surgery is still the main curative therapeutic modality for breast cancer. Although surgery often results in the successful removal of the primary tumor, its process could increase the risk of metastases of residual cancer cells. Understanding of the connection between breast cancer metastasis and surgical wound will lead to the establishment of a proper treatment strategy for postoperative cancer patient. Aim: To study the influence of surgical procedure on the metastasis of primary breast cancer. Methods: We established MDA-MB-435 human breast cancer xenograft model. Levels of Pro-matrix metalloproteinase 9 (Pro-MMP-9) and vascular endothelial growth factor (VEGF) in host serum and tumors were tested at different time points with ELISA and zymography and correlated to tumor growth and postoperative metastasis. Results: Our study demonstrated surgical wound had promoting effect on tumor growth and pulmonary metastasis of human breast cells, if tumor cells remain in bodies. This effect might be related to the postoperative interaction of cancer and host cells, which resulted in expression of Pro-MMP-9. Surgical process could also increase the VEGF expression in tumor tissues. Conclusions: Surgical wound-produced host Pro-MMP-9 and tumor cell VEGF might be important mediators leading to metastasis of residual breast cancer after surgery.Хирургическое лечение до сих пор остается главным терапевтическим подходом при лечении больных раком молочной
железы. Хотя хирургическое удаление опухоли в большинстве случаев достаточно эффективно, в то же время оно может
увеличить риск метастазирования остаточных опухолевых клеток. Понимание связи между метастазированием при раке
молочной железы и операционной раной позволит выбрать наилучшую стратегию постоперационного лечения. Цель:
определить влияние хирургического вмешательства на метастазирование опухоли. Методы: была создана модель рака
молочной железы человека в виде ксенотрансплантата MDA-MB-435. Уровень Pro-матричной металлопротеиназы 9
(Pro-MMP-9) и фактора роста эндотелия сосудов (VEGF) в сыворотке реципиента и опухолях оценивались в разные
временные промежутки методом ELISA и зимографии. При этом определяли наличие корелляции между этими показа- и зимографии. При этом определяли наличие корелляции между этими показа и зимографии. При этом определяли наличие корелляции между этими показателями,
ростом опухоли и постоперационными метастазами. Результаты: было показано, что операционная рана способствует
росту опухоли молочной железы и ее метастазированию в легкие в случае, когда при удалении опухоли в ране
остаются опухолевые клетки. Это может быть связано с постоперационным взаимодействием опухолевых и окружающих
их нормальных клеток, которое приводит к экспрессии Pro-MMP-9. Удаление опухоли может также способствовать
увеличению экспрессии VEGF опухолевыми клетками. Выводы: Pro-MMP-9, экспрессируемый нормальными клетками,
окружающими постоперационную рану, а также VEGF, продуцируемый опухолевыми клетками, могут быть важными
медиаторами метастазирования остаточных опухолевых клеток после хирургического вмешательства
Spontaneous CP Violating Phase as the Phase in PMNS Matrix
We study the possibility of identifying the CP violating phases in the PMNS
mixing matrix in the lepton sector and also that in the CKM mixing matrix in
the quark sector with the phase responsible for the spontaneous CP violation in
the Higgs potential, and some implications. Since the phase in the CKM mixing
matrix is determined by experimental data, the phase in the lepton sector is
therefore also fixed. The mass matrix for neutrinos is constrained leading to
constraints on the Jarlskog CP violating parameter , and the effective mass
for neutrinoless double beta decay. The Yukawa couplings are
also constrained. Different ways of identifying the phases have different
predictions for and . Future
experimental data can be used to distinguish different models.Comment: 16 pages, 3 figure
Spontaneous CP Violating Phase as The CKM Matrix Phase
We propose that the CP violating phase in the CKM mixing matrix is identical
to the CP phases responsible for the spontaneous CP violation in the Higgs
potential. A specific multi-Higgs model with Peccei-Quinn (PQ) symmetry is
constructed to realize this idea. The CP violating phase does not vanish when
all Higgs masses become large. There are flavor changing neutral current (FCNC)
interactions mediated by neutral Higgs bosons at the tree level. However,
unlike general multi-Higgs models, the FCNC Yukawa couplings are fixed in terms
of the quark masses and CKM mixing angles. Implications for meson-anti-meson
mixing, including recent data on mixing, and neutron electric dipole
moment (EDM) are studied. We find that the neutral Higgs boson masses can be at
the order of one hundred GeV. The neutron EDM can be close to the present
experimental upper bound.Comment: 16 pages, RevTex. Several typos corrected, and one reference adde
Charm multiplicity and the branching ratios of inclusive charmless b quark decays in the general two-Higgs-doublet models
In the framework of general two-Higgs-doublet models, we calculate the
branching ratios of various inclusive charmless b decays by using the low
energy effective Hamiltonian including next-to-leading order QCD corrections,
and examine the current status and the new physics effects on the determination
of the charm multiplicity and semileptonic branching ratio .
Within the considered parameter space, the enhancement to the ratio due to the charged-Higgs penguins can be as large as a factor of 8 (3) in
the model III (II), while the ratio can be increased from
the standard model prediction of 2.49% to 4.91% (2.99%) in the model III (II).
Consequently, the value of and can be decreased simultaneously
in the model III. The central value of will be lowered slightly by
about 0.003, but the ratio can be reduced significantly from the
theoretical prediction of in the SM to , for GeV, respectively. We find that
the predicted and the measured now agree within roughly one
standard deviation after taking into account the effects of gluonic charged
Higgs penguins in the model III with a relatively light charged Higgs boson.Comment: 25 pages, Latex file, axodraw.sty, 6 figures. Final version to be
published in Phys.Rev.
The ARGO-YBJ Experiment Progresses and Future Extension
Gamma ray source detection above 30TeV is an encouraging approach for finding
galactic cosmic ray origins. All sky survey for gamma ray sources using wide
field of view detector is essential for population accumulation for various
types of sources above 100GeV. To target the goals, the ARGO-YBJ experiment has
been established. Significant progresses have been made in the experiment. A
large air shower detector array in an area of 1km2 is proposed to boost the
sensitivity. Hybrid detection with multi-techniques will allow a good
discrimination between different types of primary particles, including photons
and protons, thus enable an energy spectrum measurement for individual specie.
Fluorescence light detector array will extend the spectrum measurement above
100PeV where the second knee is located. An energy scale determined by balloon
experiments at 10TeV will be propagated to ultra high energy cosmic ray
experiments
High Altitude test of RPCs for the ARGO-YBJ experiment
A 50 m**2 RPC carpet was operated at the YangBaJing Cosmic Ray Laboratory
(Tibet) located 4300 m a.s.l. The performance of RPCs in detecting Extensive
Air Showers was studied. Efficiency and time resolution measurements at the
pressure and temperature conditions typical of high mountain laboratories, are
reported.Comment: 16 pages, 10 figures, submitted to Nucl. Instr. Met
Measurement of the Atmospheric Muon Spectrum from 20 to 3000 GeV
The absolute muon flux between 20 GeV and 3000 GeV is measured with the L3
magnetic muon spectrometer for zenith angles ranging from 0 degree to 58
degree. Due to the large exposure of about 150 m2 sr d, and the excellent
momentum resolution of the L3 muon chambers, a precision of 2.3 % at 150 GeV in
the vertical direction is achieved.
The ratio of positive to negative muons is studied between 20 GeV and 500
GeV, and the average vertical muon charge ratio is found to be 1.285 +- 0.003
(stat.) +- 0.019 (syst.).Comment: Total 32 pages, 9Figure
ARGO-YBJ constraints on very high energy emission from GRBs
The ARGO-YBJ (Astrophysical Radiation Ground-based Observatory at YangBaJing)
experiment is designed for very high energy -astronomy and cosmic ray
researches. Due to the full coverage of a large area () with
resistive plate chambers at a very high altitude (4300 m a.s.l.), the ARGO-YBJ
detector is used to search for transient phenomena, such as Gamma-ray bursts
(GRBs). Because the ARGO-YBJ detector has a large field of view (2 sr)
and is operated with a high duty cycle (90%), it is well suited for GRB
surveying and can be operated in searches for high energy GRBs following alarms
set by satellite-borne observations at lower energies. In this paper, the
sensitivity of the ARGO-YBJ detector for GRB detection is estimated. Upper
limits to fluence with 99% confidence level for 26 GRBs inside the field of
view from June 2006 to January 2009 are set in the two energy ranges 10100
GeV and 10 GeV1 TeV.Comment: accepted for publication in Astroparticle Physic
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