105 research outputs found
Influence of a Feshbach resonance on the photoassociation of LiCs
We analyse the formation of ultracold 7Li133Cs molecules in the rovibrational
ground state through photoassociation into the B1Pi state, which has recently
been reported [J. Deiglmayr et al., Phys. Rev. Lett. 101, 133004 (2008)].
Absolute rate constants for photoassociation at large detunings from the atomic
asymptote are determined and are found to be surprisingly large. The
photoassociation process is modeled using a full coupled-channel calculation
for the continuum state, taking all relevant hyperfine states into account. The
enhancement of the photoassociation rate is found to be caused by an `echo' of
the triplet component in the singlet component of the scattering wave function
at the inner turning point of the lowest triplet a3Sigma+ potential. This
perturbation can be ascribed to the existence of a broad Feshbach resonance at
low scattering energies. Our results elucidate the important role of couplings
in the scattering wave function for the formation of deeply bound ground state
molecules via photoassociation.Comment: Added Erratum, 20 pages, 9 figure
Nonmonotonic dependence of the absolute entropy on temperature in supercooled Stillinger-Weber silicon
Using a recently developed thermodynamic integration method, we compute the
precise values of the excess Gibbs free energy (G^e) of the high density liquid
(HDL) phase with respect to the crystalline phase at different temperatures (T)
in the supercooled region of the Stillinger-Weber (SW) silicon [F. H.
Stillinger and T. A. Weber, Phys. Rev. B. 32, 5262 (1985)]. Based on the slope
of G^e with respect to T, we find that the absolute entropy of the HDL phase
increases as its enthalpy changes from the equilibrium value at T \ge 1065 K to
the value corresponding to a non-equilibrium state at 1060 K. We find that the
volume distribution in the equilibrium HDL phases become progressively broader
as the temperature is reduced to 1060 K, exhibiting van-der-Waals (VDW) loop in
the pressure-volume curves. Our results provides insight into the thermodynamic
cause of the transition from the HDL phase to the low density phases in SW
silicon, observed in earlier studies near 1060 K at zero pressure.Comment: This version is accepted for publication in Journal of Statistical
Physics (11 figures, 1 table
Formation of ultracold dipolar molecules in the lowest vibrational levels by photoassociation
We recently reported the formation of ultracold LiCs molecules in the
rovibrational ground state X1Sigma+,v''=0,J''=0 [J. Deiglmayr et al., PRL 101,
133004 (2008)]. Here we discuss details of the experimental setup and present a
thorough analysis of the photoassociation step including the photoassociation
line shape. We predict the distribution of produced ground state molecules
using accurate potential nergy curves combined with an ab-initio dipole
transition moment and compare this prediction with experimental ionization
spectra. Additionally we improve the value of the dissociation energy for the
X1Sigma+ state by high resolution spectroscopy of the vibrational ground state.Comment: Submitted to Faraday Discussions 142: Cold and Ultracold Molecules 18
pages, 8 figure
Expression of HIWI in human esophageal squamous cell carcinoma is significantly associated with poorer prognosis
<p>Abstract</p> <p>Background</p> <p>HIWI, the human homologue of Piwi family, is present in CD34<sup>+ </sup>hematopoietic stem cells and germ cells, but not in well-differentiated cell populations, indicating that HIWI may play an impotent role in determining or maintaining stemness of these cells. That HIWI expression has been detected in several type tumours may suggest its association with clinical outcome in cancer patients.</p> <p>Methods</p> <p>With the methods of real-time PCR, western blot, immunocytochemistry and immunohistochemistry, the expression of HIWI in three esophageal squamous cancer cell lines KYSE70, KYSE140 and KYSE450 has been characterized. Then, we investigated HIWI expression in a series of 153 esophageal squamous cell carcinomas using immunohistochemistry and explored its association with clinicopathological features.</p> <p>Results</p> <p>The expression of HIWI was observed in tumour cell nuclei or/and cytoplasm in 137 (89.5%) cases, 16 (10.5%) cases were negative in both nuclei and cytoplasm. 86 (56.2%) were strongly positive in cytoplasm, while 49 (32.0%) were strongly positive in nuclei. The expression level of HIWI in cytoplasm of esophageal cancer cells was significantly associated with histological grade (<it>P </it>= 0.011), T stage (<it>P </it>= 0.035), and clinic outcome (<it>P </it>< 0.001), while there was no correlation between the nuclear HIWI expression and clinicopathological features.</p> <p>Conclusion</p> <p>The expression of HIWI in the cytoplasm of esophageal cancer cells is significantly associated with higher histological grade, clinical stage and poorer clinical outcome, indicating its possible involvement in cancer development.</p
Expression of human Piwi-likegenes is associated with prognosis for soft tissue sarcoma patients
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