5,441 research outputs found
Charmless Three-body Decays of B Mesons
Charmless 3-body decays of B mesons are studied in the framework of the
factorization approach. The nonresonant contributions arising from transitions are evaluated using heavy meson chiral perturbation theory
(HMChPT). The momentum dependence of nonresonant amplitudes is assumed to be in
the exponential form e^{-\alpha_{NR}} p_B\cdot(p_i+p_j)} so that the HMChPT
results are recovered in the soft meson limit . In addition, we
have identified another large source of the nonresonant signal in the matrix
elements of scalar densities, e.g. , which can be
constrained from the decay or . The
intermediate vector meson contributions to 3-body decays are identified through
the vector current, while the scalar meson resonances are mainly associated
with the scalar density. Their effects are described in terms of the
Breit-Wigner formalism. Our main results are: (i) All KKK modes are dominated
by the nonresonant background. The predicted branching ratios of
, and modes are consistent with the
data within errors. (ii) Although the penguin-dominated
decay is subject to a potentially significant tree pollution, its effective
is very similar to that of the mode. However, direct
CP asymmetry of the former, being of order -4%, is more prominent than the
latter. (iii) For decays, we found sizable nonresonant
contributions in and modes, in agreement
with the Belle measurements but larger than the BaBar result.Comment: 39 pages, 2 figures, version to appear in PR
A Precision Microbiome Approach Using Sucrose for Selective Augmentation of Staphylococcus epidermidis Fermentation against Propionibacterium acnes.
Acne dysbiosis happens when there is a microbial imbalance of the over-growth of Propionibacterium acnes (P. acnes) in the acne microbiome. In our previous study, we demonstrated that Staphylococcus epidermidis (S. epidermidis, a probiotic skin bacterium) can exploit glycerol fermentation to produce short-chain fatty acids (SCFAs) which have antimicrobial activities to suppress the growth of P. acnes. Unlike glycerol, sucrose is chosen here as a selective fermentation initiator (SFI) that can specifically intensify the fermentation activity of S. epidermidis, but not P. acnes. A co-culture of P. acnes and fermenting S. epidermidis in the presence of sucrose significantly led to a reduction in the growth of P. acnes. The reduction was abolished when P. acnes was co-cultured with non-fermenting S. epidermidis. Results from nuclear magnetic resonance (NMR) analysis revealed four SCFAs (acetic acid, butyric acid, lactic acid, and succinic acid) were detectable in the media of S. epidermidis sucrose fermentation. To validate the interference of S. epidermidis sucrose fermentation with P. acnes, mouse ears were injected with both P. acnes and S. epidermidis plus sucrose or phosphate buffered saline (PBS). The level of macrophage-inflammatory protein-2 (MIP-2) and the number of P. acnes in ears injected with two bacteria plus sucrose were considerably lower than those in ears injected with two bacteria plus PBS. Our results demonstrate a precision microbiome approach by using sucrose as a SFI for S. epidermidis, holding future potential as a novel modality to equilibrate dysbiotic acne
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FAM129B, an antioxidative protein, reduces chemosensitivity by competing with Nrf2 for Keap1 binding.
BackgroundThe transcription factor Nrf2 is a master regulator of antioxidant response. While Nrf2 activation may counter increasing oxidative stress in aging, its activation in cancer can promote cancer progression and metastasis, and confer resistance to chemotherapy and radiotherapy. Thus, Nrf2 has been considered as a key pharmacological target. Unfortunately, there are no specific Nrf2 inhibitors for therapeutic application. Moreover, high Nrf2 activity in many tumors without Keap1 or Nrf2 mutations suggests that alternative mechanisms of Nrf2 regulation exist.MethodsInteraction of FAM129B with Keap1 is demonstrated by immunofluorescence, colocalization, co-immunoprecipitation and mammalian two-hybrid assay. Antioxidative function of FAM129B is analyzed by measuring ROS levels with DCF/flow cytometry, Nrf2 activation using luciferase reporter assay and determination of downstream gene expression by qPCR and wester blotting. Impact of FAM129B on in vivo chemosensitivity is examined in mice bearing breast and colon cancer xenografts. The clinical relevance of FAM129B is assessed by qPCR in breast cancer samples and data mining of publicly available databases.FindingsWe have demonstrated that FAM129B in cancer promotes Nrf2 activity by reducing its ubiquitination through competition with Nrf2 for Keap1 binding via its DLG and ETGE motifs. In addition, FAM129B reduces chemosensitivity by augmenting Nrf2 antioxidative signaling and confers poor prognosis in breast and lung cancer.InterpretationThese findings demonstrate the important role of FAM129B in Nrf2 activation and antioxidative response, and identify FMA129B as a potential therapeutic target. FUND: The Chang Gung Medical Foundation (Taiwan) and the Ministry of Science and Technology (Taiwan)
Environmental deterioration in rapid urbanisation: evidence from assessment of ecosystem service values in Wujiang, Suzhou
Land use change is the most prominent feature of Chinese urbanisation. In China, the expansion of land consumed for urban development is inevitable given the rapid increases in the urban economy and urban population, but also in meeting the population’s increasing demand for better quality of life. This paper is based on a research study of Wujiang district in Suzhou, which is considered representative of many of the rapid urbanisation areas within the nation. The objective is to develop an in-depth understanding of the characteristics of land use change and how this change contributes to environmental deterioration, as assessed by changes in the ecosystem service value (ESV). In this study, ESV is defined as the environmental products and functions provided for human well-being. Based on local planning documents, Landsat TM remote-sensing images and field surveys, the research analyses the cost to the environment when traditional land uses are transformed into urbanisation. The research demonstrates that conversion to urban land use which ignores the limit and capacity of the environment can generate significant environmental costs, as assessed by ESV, which in turn, can lead to a deterioration of quality of life for inhabitants, the exact opposite of the original intention. The research demonstrates that by mapping the spatial distribution of ecological service values, ESV can be used as a guide to urban sustainable development
Influence of the trap shape on the superfluid-Mott transition in ultracold atomic gases
The coexistence of superfluid and Mott insulator, due to the quadratic
confinement potential in current optical lattice experiments, makes the
accurate detection of the superfluid-Mott transition difficult. Studying
alternative trapping potentials which are experimentally realizable and have a
flatter center, we find that the transition can be better resolved, but at the
cost of a more difficult tuning of the particle filling. When mapping out the
phase diagram using local probes and the local density approximation we find
that the smoother gradient of the parabolic trap is advantageous.Comment: 5 pages, 6 figure
Beyond Gisin's Theorem and its Applications: Violation of Local Realism by Two-Party Einstein-Podolsky-Rosen Steering
We demonstrate here that for a given mixed multi-qubit state if there are at
least two observers for whom mutual Einstein-Podolsky-Rosen steering is
possible, i.e. each observer is able to steer the other qubits into two
different pure states by spontaneous collapses due to von Neumann type
measurements on his/her qubit, then nonexistence of local realistic models is
fully equivalent to quantum entanglement (this is not so without this
condition). This result leads to an enhanced version of Gisin's theorem
(originally: all pure entangled states violate local realism). Local realism is
violated by all mixed states with the above steering property. The new class of
states allows one e.g. to perform three party secret sharing with just pairs of
entangled qubits, instead of three qubit entanglements (which are currently
available with low fidelity). This significantly increases the feasibility of
having high performance versions of such protocols. Finally, we discuss some
possible applications.Comment: 9 pages, 1 figur
Malignant phyllodes tumors display mesenchymal stem cell features and aldehyde dehydrogenase/disialoganglioside identify their tumor stem cells.
IntroductionAlthough breast phyllodes tumors are rare, there is no effective therapy other than surgery. Little is known about their tumor biology. A malignant phyllodes tumor contains heterologous stromal elements, and can transform into rhabdomyosarcoma, liposarcoma and osteosarcoma. These versatile properties prompted us to explore their possible relationship to mesenchymal stem cells (MSCs) and to search for the presence of cancer stem cells (CSCs) in phyllodes tumors.MethodsParaffin sections of malignant phyllodes tumors were examined for various markers by immunohistochemical staining. Xenografts of human primary phyllodes tumors were established by injecting freshly isolated tumor cells into the mammary fat pad of non-obese diabetic-severe combined immunodeficient (NOD-SCID) mice. To search for CSCs, xenografted tumor cells were sorted into various subpopulations by flow cytometry and examined for their in vitro mammosphere forming capacity, in vivo tumorigenicity in NOD-SCID mice and their ability to undergo differentiation.ResultsImmunohistochemical analysis revealed the expression of the following 10 markers: CD44, CD29, CD106, CD166, CD105, CD90, disialoganglioside (GD2), CD117, Aldehyde dehydrogenase 1 (ALDH), and Oct-4, and 7 clinically relevant markers (CD10, CD34, p53, p63, Ki-67, Bcl-2, vimentin, and Globo H) in all 51 malignant phyllodes tumors examined, albeit to different extents. Four xenografts were successfully established from human primary phyllodes tumors. In vitro, ALDH+ cells sorted from xenografts displayed approximately 10-fold greater mammosphere-forming capacity than ALDH- cells. GD2+ cells showed a 3.9-fold greater capacity than GD2- cells. ALDH+/GD2+cells displayed 12.8-fold greater mammosphere forming ability than ALDH-/GD2- cells. In vivo, the tumor-initiating frequency of ALDH+/GD2+ cells were up to 33-fold higher than that of ALDH+ cells, with as few as 50 ALDH+/GD2+ cells being sufficient for engraftment. Moreover, we provided the first evidence for the induction of ALDH+/GD2+ cells to differentiate into neural cells of various lineages, along with the observation of neural differentiation in clinical specimens and xenografts of malignant phyllodes tumors. ALDH+ or ALDH+/GD2+ cells could also be induced to differentiate into adipocytes, osteocytes or chondrocytes.ConclusionsOur findings revealed that malignant phyllodes tumors possessed many characteristics of MSC, and their CSCs were enriched in ALDH+ and ALDH+/GD2+ subpopulations
Silicon-organic hybrid thermo-optic switch based on a slot waveguide directional coupler
We propose and demonstrate a passively biased 2 by 2 thermo-optic switch with
high power efficiency and fast response time. The device benefits from the
highly concentrated optical field of a slot waveguide mode and the strong
thermo-optic effect of a nematic liquid crystal (NLC) cladding. The NLC fills
the nano-slot region and is aligned by the subwavelength grating inside. The
measured power consumption and thermal time constant are 0.58 mW and 11.8
microsecond, respectively, corresponding to a figure-of-merit of 6.8. The
proposed silicon-organic hybrid device provides a new solution to design
thermo-optic actuators having lower power consumption and fast operation speed
A convenient tandem one-pot synthesis of donor-acceptor-type triphenylene 2,3-dicarboxylic esters from diarylacetylene
A tandem one-pot method for the direct synthesis of polysubstituted triphenylene 2,3-dicarboxylic esters with different substitution patterns was developed by enyne metathesis of diarylacetylene, followed by Diels–Alder, aromatization and a cyclization cascade
A Phenomenological Theory of The Pseudogap State
An ansatz is proposed for the coherent part of the single particle Green's
function in a doped resonant valence bond (RVB) state by, analogy with the form
derived by Konik and coworkers for a doped spin liquid formed by an array of
2-leg Hubbard ladders near half-filling. The parameters of the RVB state are
taken from the renormalized mean field theory of Zhang and coworkers for
underdoped cuprates. The ansatz shows good agreement with recent angle resolved
photoemission (ARPES) on underdoped cuprates and resolves an apparent
disagreement with the Luttinger Sum Rule. The transition in the normal state
from a doped RVB spin liquid to a standard Landau Fermi liquid, that occurs in
the renormalized mean field theory, appears as a quantum critical point
characterized by a change in the analytic form of the Green's function. A
d-wave superconducting dome surrounding this quantum critical point is
introduced phenomenologically. Results are also presented for the Drude weight
and tunneling density of states as functions of the hole density.Comment: 11 pages, 14 figure
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