2,678 research outputs found
ERα inhibits epithelial-mesenchymal transition by suppressing Bmi1 in breast cancer
published_or_final_versio
Experimental investigation of classical and quantum correlations under decoherence
It is well known that many operations in quantum information processing
depend largely on a special kind of quantum correlation, that is, entanglement.
However, there are also quantum tasks that display the quantum advantage
without entanglement. Distinguishing classical and quantum correlations in
quantum systems is therefore of both fundamental and practical importance. In
consideration of the unavoidable interaction between correlated systems and the
environment, understanding the dynamics of correlations would stimulate great
interest. In this study, we investigate the dynamics of different kinds of
bipartite correlations in an all-optical experimental setup. The sudden change
in behaviour in the decay rates of correlations and their immunity against
certain decoherences are shown. Moreover, quantum correlation is observed to be
larger than classical correlation, which disproves the early conjecture that
classical correlation is always greater than quantum correlation. Our
observations may be important for quantum information processing.Comment: 7 pages, 4 figures, to appear in Nature Communication
ERα inhibits epithelial-mesenchymal transition by suppressing Bmi1 in breast cancer
published_or_final_versio
Macroscopic invisibility cloaking of visible light
Invisibility cloaks, which used to be confined to the realm of fiction, have now been turned into a scientific reality thanks to the enabling theoretical tools of transformation optics and conformal mapping. Inspired by those theoretical works, the experimental realization of electromagnetic invisibility cloaks has been reported at various electromagnetic frequencies. All the invisibility cloaks demonstrated thus far, however, have relied on nano- or micro-fabricated artificial composite materials with spatially varying electromagnetic properties, which limit the size of the cloaked region to a few wavelengths. Here, we report the first realization of a macroscopic volumetric invisibility cloak constructed from natural birefringent crystals. The cloak operates at visible frequencies and is capable of hiding, for a specific light polarization, three-dimensional objects of the scale of centimetres and millimetres. Our work opens avenues for future applications with macroscopic cloaking devices
Why should we care about quantum discord?
Entanglement is a central feature of quantum theory. Mathematical properties
and physical applications of pure state entanglement make it a template to
study quantum correlations. However, an extension of entanglement measures to
mixed states in terms of separability does not always correspond to all the
operational aspects. Quantum discord measures allow an alternative way to
extend the idea of quantum correlations to mixed states. In many cases these
extensions are motivated by physical scenarios and quantum information
protocols. In this chapter we discuss several settings involving correlated
quantum systems, ranging from distributed gates to detectors testing quantum
fields. In each setting we show how entanglement fails to capture the relevant
features of the correlated system, and discuss the role of discord as a
possible alternative.Comment: Written for "Lectures on general quantum correlations and their
applications
Prevalence of Oral Pain and Barriers to use of Emergency Oral Care Facilities Among Adult Tanzanians.
Oral pain has been the major cause of the attendances in the dental clinics in Tanzania. Some patients postpone seeing the dentist for as long as two to five days. This study determines the prevalence of oral pain and barriers to use of emergency oral care in Tanzania. Questionnaire data were collected from 1,759 adult respondents aged 18 years and above. The study area covered six urban and eight rural study clusters, which had been selected using the WHO Pathfinder methodology. Chi-square tests and logistic regression analyses were performed to identify associations.\ud
Forty two percent of the respondents had utilized the oral health care facilities sometimes in their lifetime. About 59% of the respondents revealed that they had suffered from oral pain and/or discomfort within the twelve months that preceded the study, but only 26.5% of these had sought treatment from oral health care facilities. The reasons for not seeking emergency care were: lack of money to pay for treatment (27.9%); self medication (17.6%); respondents thinking that pain would disappear with time (15.7%); and lack of money to pay for transport to the dental clinic (15.0%). Older adults were more likely to report that they had experienced oral pain during the last 12 months than the younger adults (OR = 1.57, CI 1.07-1.57, P < 0.001). Respondents from rural areas were more likely report dental clinics far from home (OR = 5.31, CI = 2.09-13.54, P < 0.001); self medication at home (OR = 3.65, CI = 2.25-5.94, P < 0.001); and being treated by traditional healer (OR = 5.31, CI = 2.25-12.49, P < 0.001) as reasons for not seeking emergency care from the oral health care facilities than their counterparts from urban areas. Oral pain and discomfort were prevalent among adult Tanzanians. Only a quarter of those who experienced oral pain or discomfort sought emergency oral care from oral health care facilities. Self medication was used as an alternative to using oral care facilities mainly by rural residents. Establishing oral care facilities in rural areas is recommended
Operational Significance of Discord Consumption: Theory and Experiment
Coherent interactions that generate negligible entanglement can still exhibit
unique quantum behaviour. This observation has motivated a search beyond
entanglement for a complete description of all quantum correlations. Quantum
discord is a promising candidate. Here, we demonstrate that under certain
measurement constraints, discord between bipartite systems can be consumed to
encode information that can only be accessed by coherent quantum interactions.
The inability to access this information by any other means allows us to use
discord to directly quantify this `quantum advantage'. We experimentally encode
information within the discordant correlations of two separable Gaussian
states. The amount of extra information recovered by coherent interaction is
quantified and directly linked with the discord consumed during encoding. No
entanglement exists at any point of this experiment. Thus we introduce and
demonstrate an operational method to use discord as a physical resource.Comment: 10 pages, 3 figures, updated with Nature Physics Reference,
simplified proof in Appendi
The sudden change phenomenon of quantum discord
Even if the parameters determining a system's state are varied smoothly, the
behavior of quantum correlations alike to quantum discord, and of its classical
counterparts, can be very peculiar, with the appearance of non-analyticities in
its rate of change. Here we review this sudden change phenomenon (SCP)
discussing some important points related to it: Its uncovering,
interpretations, and experimental verifications, its use in the context of the
emergence of the pointer basis in a quantum measurement process, its appearance
and universality under Markovian and non-Markovian dynamics, its theoretical
and experimental investigation in some other physical scenarios, and the
related phenomenon of double sudden change of trace distance discord. Several
open questions are identified, and we envisage that in answering them we will
gain significant further insight about the relation between the SCP and the
symmetry-geometric aspects of the quantum state space.Comment: Lectures on General Quantum Correlations and their Applications, F.
F. Fanchini, D. O. Soares Pinto, and G. Adesso (Eds.), Springer (2017), pp
309-33
Variations in Mre11/Rad50/Nbs1 status and DNA damage-induced S-phase arrest in the cell lines of the NCI60 panel
<p>Abstract</p> <p>Background</p> <p>The Mre11/Rad50/Nbs1 (MRN) complex is a regulator of cell cycle checkpoints and DNA repair. Defects in MRN can lead to defective S-phase arrest when cells are damaged. Such defects may elicit sensitivity to selected drugs providing a chemical synthetic lethal interaction that could be used to target therapy to tumors with these defects. The goal of this study was to identify these defects in the NCI60 panel of cell lines and identify compounds that might elicit selective cytotoxicity.</p> <p>Methods</p> <p>We screened the NCI60 panel in search of cell lines that express low levels of MRN proteins, or that fail to arrest in S-phase in response to the topisomerase I inhibitor SN38. The NCI COMPARE program was used to discover compounds that preferentially target cells with these phenotypes.</p> <p>Results</p> <p>HCT116 cells were initially identified as defective in MRN and S phase arrest. Transfection with Mre11 also elevated Rad50 and Nbs1, and rescued the defective S-phase arrest. Cells of the NCI60 panel exhibited a large range of protein expression but a strong correlation existed between Mre11, Rad50 and Nbs1 consistent with complex formation determining protein stability. Mre11 mRNA correlated best with protein level suggesting it was the primary determinant of the overall level of the complex. Three other cell lines failed to arrest in response to SN38, two of which also had low MRN. However, other cell lines with low MRN still arrested suggesting low MRN does not predict an inability to arrest. Many compounds, including a family of benzothiazoles, correlated with the failure to arrest in S phase. The activity of benzothiazoles has been attributed to metabolic activation and DNA alkylation, but we note several cell lines in which sensitivity does not correlate with metabolism. We propose that the checkpoint defect imposes an additional mechanism of sensitivity on cells.</p> <p>Conclusions</p> <p>We have identified cells with possible defects in the MRN complex and S phase arrest, and a series of compounds that may preferentially target S phase-defective cells. We discuss limitations of the COMPARE program when attempting to identify compounds that selectively inhibit only a few cell lines.</p
Quantum Discord and entropic measures of quantum correlations: Optimization and behavior in finite spin chains
We discuss a generalization of the conditional entropy and one-way
information deficit in quantum systems, based on general entropic forms. The
formalism allows to consider simple entropic forms for which a closed
evaluation of the associated optimization problem in qudit-qubit systems is
shown to become feasible, allowing to approximate that of the quantum discord.
As application, we examine quantum correlations of spin pairs in the exact
ground state of finite spin chains in a magnetic field through the quantum
discord and information deficit. While these quantities show a similar
behavior, their optimizing measurements exhibit significant differences, which
can be understood and predicted through the previous approximations. The
remarkable behavior of these quantities in the vicinity of transverse and
non-transverse factorizing fields is also discussed.Comment: 10 pages, 3 figure
- …