6,415 research outputs found
Non-canonical statistics of finite quantum system
The canonical statistics describes the statistical properties of an open
system by assuming its coupling with the heat bath infinitesimal in comparison
with the total energy in thermodynamic limit. In this paper, we generally
derive a non-canonical distribution for the open system with a finite coupling
to the heat bath, which deforms the energy shell to effectively modify the
conventional canonical way. The obtained non-canonical distribution reflects
the back action of system on the bath, and thus depicts the statistical
correlations through energy fluctuations
Dedifferentiation: A new approach in stem cell research
Dedifferentiation is an important biological phenomenon whereby cells regress from a specialized function to a simpler state reminiscent of stem cells. Stem cells are self-renewing cells capable of giving rise to differentiated cells when supplied with the appropriate factors. Stem cells that are derived by dedifferentiation of one's own cells could be a new resource for regenerative medicine, one that poses no risk of genetic incompatibility or immune rejection and provokes fewer ethical debates than the use of stem cells derived from embryonic tissue. Until now, it has not been quite clear why some differentiated cell types can dedifferentiate and proliferate, whereas others cannot. A better understanding of the mechanisms involved in dedifferentiation may enable scientists to control and possibly alter the plasticity of the differentiated state, which may lead to benefits not only in stem cell research but also in regenerative medicine and even tumor biology. If so, dedifferentiation will offer an ethically acceptable alternative route to obtain an abundant source of stem cells. Dedifferentiation is likely to become a new focus of stem cell research. Here we compile recent advances in this emerging but significant research, highlighting its central concepts, research findings, possible signaling pathways, and potential applications.published_or_final_versio
Manipulation of heat current by the interface between graphene and white graphene
We investigate the heat current flowing across the interface between graphene
and hexagonal boron nitride (so-called white graphene) using both molecular
dynamics simulation and nonequilibrium Green's function approaches. These two
distinct methods discover the same phenomena that the heat current is reduced
linearly with increasing interface length, and the zigzag interface causes
stronger reduction of heat current than the armchair interface. These phenomena
are interpreted by both the lattice dynamics analysis and the transmission
function explanation, which both reveal that the localized phonon modes at
interfaces are responsible for the heat management. The room temperature
interface thermal resistance is about mK/W in zigzag
interface and mK/W in armchair interface, which
directly results in stronger heat reduction in zigzag interface. Our
theoretical results provide a specific route for experimentalists to control
the heat transport in the graphene and hexagonal boron nitride compound through
shaping the interface between these two materials.Comment: accepted by EP
Evaluation of genetic diversity in self-incompatible broccoli DH lines assessed by SRAP markers
In this article, we investigated self-compatibility index (SCI) in broccoli double haploid (DH) lines, and the relationship and genetic diversity of 15 self-incompatible (SI) broccoli DH lines were analyzed by sequence related amplified polymorphism (SRAP). 11 primer combinations selected from 88 primer pairs revealed a total number of 129 unambiguous bands, 61 of which were polymorphic with a polymorphism frequency of 47.3%. Analyzed by NTSYS software, the genetic similarity coefficient of the 15 broccoli resources ranged from 0.76 to 0.98. Based on the coefficient value of 0.79, these broccoli DH lines were clustered into three multiple-member groups by unweighted pair group method with arithmetic mean (UPGMA) analysis, which provided molecular reference for parent selection in broccoli breeding.Key words: Brassica oleracea L. var. italica, self-compatibility index, double haploid, genetic diversity, sequence related amplified polymorphism (SRAP)
Achieving economically sustainable subcontracting through the hotelling model by considering the spillover effect
In the process of internationalization of construction contractors, international enterprises as main contractors (IMC) need to consider whether part of the contract should be subcontracted to local subcontractors (LSC) to gain a competitive advantage when competing with local main contractors (LMC). The involvement of local subcontractors can usually help reduce cost through the cost spillover effect. However, it should be noted that the share of local subcontractors with local main contractors with an inferior quality may lead to quality spillover. The Hotelling model is therefore adopted to investigate the subcontracting decisions of main contractors considering both cost and quality spillover effects. Many scenarios are simulated and the results show that LMCs with inferior quality can always choose the subcontracting strategy to obtain increased profit regardless of the strategy that IMCs adopt. On the other hand, IMCs need to balance the cost spillover of subcontracting and the quality spillover for improving the quality level of LSCs. The results are useful for contractors to make decisions that are relevant to the adoption of subcontracting strategies to obtain competitive advantages
- …