1,182 research outputs found
Boundary operators in minimal Liouville gravity and matrix models
We interpret the matrix boundaries of the one matrix model (1MM) recently
constructed by two of the authors as an outcome of a relation among FZZT
branes. In the double scaling limit, the 1MM is described by the (2,2p+1)
minimal Liouville gravity. These matrix operators are shown to create a
boundary with matter boundary conditions given by the Cardy states. We also
demonstrate a recursion relation among the matrix disc correlator with two
different boundaries. This construction is then extended to the two matrix
model and the disc correlator with two boundaries is compared with the
Liouville boundary two point functions. In addition, the realization within the
matrix model of several symmetries among FZZT branes is discussed.Comment: 26 page
Random volumes from matrices
We propose a class of models which generate three-dimensional random volumes,
where each configuration consists of triangles glued together along multiple
hinges. The models have matrices as the dynamical variables and are
characterized by semisimple associative algebras A. Although most of the
diagrams represent configurations which are not manifolds, we show that the set
of possible diagrams can be drastically reduced such that only (and all of the)
three-dimensional manifolds with tetrahedral decompositions appear, by
introducing a color structure and taking an appropriate large N limit. We
examine the analytic properties when A is a matrix ring or a group ring, and
show that the models with matrix ring have a novel strong-weak duality which
interchanges the roles of triangles and hinges. We also give a brief comment on
the relationship of our models with the colored tensor models.Comment: 33 pages, 31 figures. Typos correcte
The Combinatorics of Alternating Tangles: from theory to computerized enumeration
We study the enumeration of alternating links and tangles, considered up to
topological (flype) equivalences. A weight is given to each connected
component, and in particular the limit yields information about
(alternating) knots. Using a finite renormalization scheme for an associated
matrix model, we first reduce the task to that of enumerating planar
tetravalent diagrams with two types of vertices (self-intersections and
tangencies), where now the subtle issue of topological equivalences has been
eliminated. The number of such diagrams with vertices scales as for
. We next show how to efficiently enumerate these diagrams (in time
) by using a transfer matrix method. We give results for various
generating functions up to 22 crossings. We then comment on their large-order
asymptotic behavior.Comment: proceedings European Summer School St-Petersburg 200
CHD pile performance, Part I:Physical modelling
The Continuous Helical Displacement (CHD) pile is an auger displacement pile developed by Roger Bullivant Ltd in the UK. It has performance characteristics of both displacement and non-displacement piles due to the nature in which it is installed. Based on field experience, it has been shown that the load-settlement performance of the CHD installed in sand exceeds the current design predictions based upon conservative effective pile diameter and design parameters associated with auger bored or continuous flight auger (CFA) cast in-situ piles. In an effort to gain a greater understanding of the performance of the CHD pile compared with more conventional piling techniques, a programme of model pile testing and associated Finite Element Modelling (the subject of a Companion Paper) in sand was undertaken. The model testing programme established that greater shaft resistance may be developed for CHD piles than had originally been considered. Based upon the results of the model testing, recommendations for more appropriate approaches to the selection of end bearing and shaft resistance factors are made to predict ultimate load capacity in sand
On Invariant Structures of Black Hole Charges
We study "minimal degree" complete bases of duality- and "horizontal"-
invariant homogeneous polynomials in the flux representation of two-centered
black hole solutions in two classes of D=4 Einstein supergravity models with
symmetric vector multiplets' scalar manifolds. Both classes exhibit an SL(2,R)
"horizontal" symmetry. The first class encompasses N=2 and N=4 matter-coupled
theories, with semi-simple U-duality given by SL(2,R) x SO(m,n); the analysis
is carried out in the so-called Calabi-Vesentini symplectic frame (exhibiting
maximal manifest covariance) and until order six in the fluxes included. The
second class, exhibiting a non-trivial "horizontal" stabilizer SO(2), includes
N=2 minimally coupled and N=3 matter coupled theories, with U-duality given by
the pseudo-unitary group U(r,s) (related to complex flux representations).
Finally, we comment on the formulation of special Kaehler geometry in terms of
"generalized" groups of type E7.Comment: 1+24 pages; 1 Table. v2 : Eqs. (1.2) and (1.3) added; Eq. (2.87)
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Distinct genes related to drug response identified in ER positive and ER negative breast cancer cell lines
Breast cancer patients have different responses to chemotherapeutic treatments. Genes associated with drug response can provide insight to understand the mechanisms of drug resistance, identify promising therapeutic opportunities, and facilitate personalized treatment. Estrogen receptor (ER) positive and ER negative breast cancer have distinct clinical behavior and molecular properties. However, to date, few studies have rigorously assessed drug response genes in them. In this study, our goal was to systematically identify genes associated with multidrug response in ER positive and ER negative breast cancer cell lines. We tested 27 human breast cell lines for response to seven chemotherapeutic agents (cyclophosphamide, docetaxel, doxorubicin, epirubicin, fluorouracil, gemcitabine, and paclitaxel). We integrated publicly available gene expression profiles of these cell lines with their in vitro drug response patterns, then applied meta-analysis to identify genes related to multidrug response in ER positive and ER negative cells separately. One hundred eighty-eight genes were identified as related to multidrug response in ER positive and 32 genes in ER negative breast cell lines. Of these, only three genes (DBI, TOP2A, and PMVK) were common to both cell types. TOP2A was positively associated with drug response, and DBI was negatively associated with drug response. Interestingly, PMVK was positively associated with drug response in ER positive cells and negatively in ER negative cells. Functional analysis showed that while cell cycle affects drug response in both ER positive and negative cells, most biological processes that are involved in drug response are distinct. A number of signaling pathways that are uniquely enriched in ER positive cells have complex cross talk with ER signaling, while in ER negative cells, enriched pathways are related to metabolic functions. Taken together, our analysis indicates that distinct mechanisms are involved in multidrug response in ER positive and ER negative breast cells. © 2012 Shen et al
Epithelial damage and tissue γδ T cells promote a unique tumor-protective IgE response
IgE is an ancient and conserved immunoglobulin isotype with potent immunological function. Nevertheless, the regulation of IgE responses remains an enigma, and evidence of a role for IgE in host defense is limited. Here we report that topical exposure to a common environmental DNA-damaging xenobiotic initiated stress surveillance by γδTCR+ intraepithelial lymphocytes that resulted in class switching to IgE in B cells and the accumulation of autoreactive IgE. High-throughput antibody sequencing revealed that γδ T cells shaped the IgE repertoire by supporting specific variable-diversity-joining (VDJ) rearrangements with unique characteristics of the complementarity-determining region CDRH3. This endogenous IgE response, via the IgE receptor FcεRI, provided protection against epithelial carcinogenesis, and expression of the gene encoding FcεRI in human squamous-cell carcinoma correlated with good disease prognosis. These data indicate a joint role for immunosurveillance by T cells and by B cells in epithelial tissues and suggest that IgE is part of the host defense against epithelial damage and tumor development
Suppression of Lung Adenocarcinoma Progression by Nkx2-1
Despite the high prevalence and poor outcome of patients with
metastatic lung cancer the mechanisms of tumour progression and
metastasis remain largely uncharacterized. Here we modelled
human lung adenocarcinoma, which frequently harbours activating
point mutations in KRAS and inactivation of the p53 pathway,
using conditional alleles in mice. Lentiviral-mediated somatic
activation of oncogenic Kras and deletion of p53 in the lung epithelial
cells of Kras[superscript LSL-G12D/+];p53[superscript flox/flox] mice initiates lung adenocarcinoma
development4. Although tumours are initiated synchronously
by defined genetic alterations, only a subset becomes malignant,
indicating that disease progression requires additional alterations.
Identification of the lentiviral integration sites allowed us to distinguish
metastatic from non-metastatic tumours and determine the
gene expression alterations that distinguish these tumour types.
Cross-species analysis identified the NK2-related homeobox transcription
factor Nkx2-1 (also called Ttf-1 or Titf1) as a candidate
suppressor of malignant progression. In this mouse model, Nkx2-1
negativity is pathognomonic of high-grade poorly differentiated
tumours. Gain- and loss-of-function experiments in cells derived
from metastatic and non-metastatic tumours demonstrated that
Nkx2-1 controls tumour differentiation and limitsmetastatic potential
in vivo. Interrogation of Nkx2-1-regulated genes, analysis of
tumours at defined developmental stages, and functional complementation
experiments indicate that Nkx2-1 constrains tumours in
part by repressing the embryonically restricted chromatin regulator
Hmga2. Whereas focal amplification of NKX2-1 in a fraction of
human lung adenocarcinomas has focused attention on its oncogenic
function, our data specifically link Nkx2-1 downregulation
to loss of differentiation, enhanced tumour seeding ability and
increased metastatic proclivity. Thus, the oncogenic and suppressive
functions ofNkx2-1 in the sametumourNational Institutes of Health (U.S.) (grant U01-CA84306 )National Institutes of Health (U.S.) (grant K99-CA151968)Howard Hughes Medical InstituteLudwig Center for Molecular OncologyNational Cancer Institute (U.S.) (Cancer Center Support (core) grant P30-CA14051
Quantifying garnet-melt trace element partitioning using lattice-strain theory: New crystal-chemical and thermodynamic constraints
Many geochemical models of major igneous differentiation events on the Earth, the Moon, and Mars invoke the presence of garnet or its high-pressure majoritic equivalent as a residual phase, based on its ability to fractionate critical trace element pairs (Lu/Hf, U/Th, heavy REE/light REE). As a result, quantitative descriptions of mid-ocean ridge and hot spot magmatism, and lunar, martian, and terrestrial magma oceans require knowledge of garnet-melt partition coefficients over a wide range of conditions. In this contribution, we present new crystal-chemical and thermodynamic constraints on the partitioning of rare earth elements (REE), Y and Sc between garnet and anhydrous silicate melt as a function of pressure (P), temperature (T), and composition (X). Our approach is based on the interpretation of experimentally determined values of partition coefficients D using lattice-strain theory. In this and a companion paper (Draper and van Westrenen this issue) we derive new predictive equations for the ideal ionic radius of the dodecahedral garnet X-site,
STUDI EKSPERIMENTAL KARAKTERISTIK KUAT TEKAN DAN KARAKTERISTIK PEMBAKARAN BRIKET DAUN CENGKEH DAN JERAMI PADI
Penelitian ini mempelajari tentang karakteristik kuat tekan dan karakteristik
pembakaran briket daun cengkeh dan jerami padi. Pembriketan dilakukan dengan
menggunakan mesin pres hidrolik dengan tekanan pembriketan sebesar 450
kg/cm2, dengan bahan pengikat dan tanpa bahan pengikat. Bahan pengikat yang
digunakan adalah lem kanji dengan kadar 5 %. Briket berbentuk silinder dengan
diameter sekitar 3 cm dan tinggi 5 cm. Variasi parameter pembriketan yang
digunakan adalah ukuran butir 20, 40 dan 80 mesh, kadar air 15 %, 20 % dan 25
%, serta suhu pembriketan sebesar 60 oC, 80 oC, 100 oC dan 120 oC. Uji
pembakaran dilakukan dalam tungku berbentuk tabung horisontal berdiameter
dalam 170 mm. Variasi perameter uji pembakaran yang digunakan adalah
kecepatan aliran udara sebesar 0,6 m/s; 0,8 m/s; 1,0 m/s dan 1,2 m/s serta variasi
ukuran butir sebesar 20, 40, dan 80 mesh. Suhu pembriketan berpengaruh
signifikan terhadap peningkatan kuat tekan briket. Dari hasil uji pembakaran
dapat ditentukan besarnya laju pembakaran, profil suhu pembakaran, nilai energi
aktivasi (E ), konstanta Arrhenius (A), dan emisi CO. Dari semua percobaan,
kadar emisi CO puncak lebih dari 400 ppm.
Kata kunci: kuat tekan, daun cengkeh, jerami, bahan pengikat, ukuran butir,
suhu pembriketan, kadar air, laju pembakaran, energi aktivasi,
emisi CO.
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