1,114 research outputs found
Granger causality and transfer entropy are equivalent for Gaussian variables
Granger causality is a statistical notion of causal influence based on
prediction via vector autoregression. Developed originally in the field of
econometrics, it has since found application in a broader arena, particularly
in neuroscience. More recently transfer entropy, an information-theoretic
measure of time-directed information transfer between jointly dependent
processes, has gained traction in a similarly wide field. While it has been
recognized that the two concepts must be related, the exact relationship has
until now not been formally described. Here we show that for Gaussian
variables, Granger causality and transfer entropy are entirely equivalent, thus
bridging autoregressive and information-theoretic approaches to data-driven
causal inference.Comment: In review, Phys. Rev. Lett., Nov. 200
Clinically Undiagnosed Prostate Carcinoma Metastatic to Renal Oncocytoma
Tumors-to-tumor metastasis is an uncommon occurrence and can be a source of great diagnostic difficulty, especially when the donor tumor is undiagnosed. Here we report a case of a kidney resected for a primary neoplasm (oncocytoma) that harbored metastases from a clinically undiagnosed prostatic adenocarcinoma. The presence of the poorly differentiated metastasis within an otherwise typical oncocytoma in the absence of metastases in the surrounding nonneoplastic renal parenchyma resulted in a diagnostic dilemma. To our knowledge, this is the first report of a case in the English literature of a clinically undiagnosed prostatic adenocarcinoma metastatic to a renal oncocytoma identified on examination of the resected renal neoplasm
Quantum state discrimination: a geometric approach
We analyse the problem of finding sets of quantum states that can be
deterministically discriminated. From a geometric point of view this problem is
equivalent to that of embedding a simplex of points whose distances are maximal
with respect to the Bures distance (or trace distance). We derive upper and
lower bounds for the trace distance and for the fidelity between two quantum
states, which imply bounds for the Bures distance between the unitary orbits of
both states. We thus show that when analysing minimal and maximal distances
between states of fixed spectra it is sufficient to consider diagonal states
only. Hence considering optimal discrimination, given freedom up to unitary
orbits, it is sufficient to consider diagonal states. This is illustrated
geometrically in terms of Weyl chambers.Comment: 12 pages, 2 figure
Symplectic geometry of entanglement
We present a description of entanglement in composite quantum systems in
terms of symplectic geometry. We provide a symplectic characterization of sets
of equally entangled states as orbits of group actions in the space of states.
In particular, using Kostant-Sternberg theorem, we show that separable states
form a unique Kaehler orbit, whereas orbits of entanglement states are
characterized by different degrees of degeneracy of the canonical symplectic
form on the complex projective space. The degree of degeneracy may be thus used
as a new geometric measure of entanglement and we show how to calculate it for
various multiparticle systems providing also simple criteria of separability.
The presented method is general and can be applied also under different
additional symmetry conditions stemming, eg. from the indistinguishability of
particles.Comment: LaTex, 31 pages, typos correcte
Altered expression of transmembrane mucins, MUC1 and MUC4, in bladder cancer: pathological implications in diagnosis.
PURPOSE: Radical changes in both expression and glycosylation pattern of transmembrane mucins have been observed in various malignancies. We and others have shown that MUC1 and MUC4, two transmembrane mucins, play a sentinel role in cell signaling events that drive several epithelial malignancies. In the present study, we investigated the expression profile of MUC1 and MUC4 in the non-neoplastic bladder urothelium, in various malignant neoplasms of bladder and in bladder carcinoma cell lines.
MATERIAL AND METHODS: Immunohistochemistry was performed on tissue sections from the urinary bladder biopsies, resection samples and tissue microarrays (TMAs) with monoclonal antibodies specific for MUC1 and MUC4. We also investigated their expression in bladder carcinoma cell lines by RT-PCR and immunoblotting.
RESULTS: MUC1 is expressed on the apical surface or in umbrella cells of the normal non-neoplastic bladder urothelium. Strong expression of MUC1 was also observed in urothelial carcinoma (UC). MUC1 staining increased from normal urothelium (nâ=â27, 0.35±0.12) to urothelial carcinoma (UC, nâ=â323, H-score, 2.4±0.22, pâ€0.0001). In contrast to MUC1, MUC4 was expressed in all the layers of non-neoplastic bladder urothelium (nâ=â14, 2.5±0.28), both in the cell membrane and cytoplasm. In comparison to non-neoplastic urothelium, the loss of MUC4 expression was observed during urothelial carcinoma (nâ=â211, 0.56±0.06). However, re-expression of MUC4 was observed in a subset of metastatic cases of urothelial carcinoma (mean H-score 0.734±0.9).
CONCLUSION: The expression of MUC1 is increased while that of MUC4 decreased in UC compared to the normal non-neoplastic urothelium. Expression of both MUC1 and MUC4, however, are significantly higher in urothelial carcinoma metastatic cases compared to localized UC. These results suggest differential expression of MUC1 and MUC4 during development and progression of bladder carcinoma
Hybrid Decays
The heavy quark expansion of Quantum Chromodynamics and the strong coupling
flux tube picture of nonperturbative glue are employed to develop the
phenomenology of hybrid meson decays. The decay mechanism explicitly couples
gluonic degrees of freedom to the pair produced quarks and hence does not obey
the well known, but model-dependent, selection rule which states that hybrids
do not decay to pairs of L=0 mesons. However, the nonperturbative nature of
gluonic excitations in the flux tube picture leads to a new selection rule:
light hybrids do not decay to pairs of identical mesons. New features of the
model are highlighted and partial widths are presented for several low lying
hybrid states.Comment: 13 pages, 1 table, revte
Viscosity and Rotation in Core-Collapse Supernovae
We construct models of core-collapse supernovae in one spatial dimension,
including rotation, angular momentum transport, and viscous dissipation
employing an alpha-prescription. We compare the evolution of a fiducial 11
M_sun non-rotating progenitor with its evolution including a wide range of
imposed initial rotation profiles (1.25<P_0<8 s, where P_0 is the initial,
approximately solid-body, rotation period of the iron core). This range of P_0
covers the region of parameter space from where rotation begins to modify the
dynamics (P_0~8 s) to where angular velocities at collapse approach Keplerian
(P_0~1 s). Assuming strict angular momentum conservation, all models in this
range leave behind neutron stars with spin periods <10 ms, shorter than those
of most radio pulsars, but similar to those expected theoretically for
magnetars at birth. A fraction of the gravitational binding energy of collapse
is stored in the free energy of differential rotation. This energy source may
be tapped by viscous processes, providing a mechanism for energy deposition
that is not strongly coupled to the mass accretion rate through the stalled
supernova shock. This effect yields qualitatively new dynamics in models of
supernovae. We explore several potential mechanisms for viscosity in the
core-collapse environment: neutrino viscosity, turbulent viscosity caused by
the magnetorotational instability (MRI), and turbulent viscosity by entropy-
and composition-gradient-driven convection. We argue that the MRI is the most
effective. We find that for rotation periods in the range P_0<~5 s, and a range
of viscous stresses, that the post-bounce dynamics is significantly effected by
the inclusion of this extra energy deposition mechanism; in several cases we
obtain strong supernova explosions.Comment: accepted to ApJ, references added, discussion tightened, 26 pages, 11
figures, emulateap
Enhanced Biological Activity of BMPâ2 Bound to SurfaceâGrafted Heparan Sulfate
Over the last decade, there has been a growing interest in the development of new materials to improve bone morphogenetic proteinâ2 (BMPâ2) delivery for tissue regeneration. This study reports the development and application of model surfaces that present BMPâ2 via heparan sulfate (HS), a ubiquitous component of the extracellular matrix (ECM). On these surfaces, HS is grafted by its reducing end, to mimic the natural arrangement of HS proteoglycans in the ECM. The binding of each component on these biomimetic surfaces is highly controlled, in terms of stoichiometry of molecules and BMPâ2/graftedâHS affinity, as determined by surfaceâsensitive techniques. For comparison, this study also uses surfaces presenting immobilized BMPâ2 alone. Functional validations of the surfaces are performed using a murine myoblast cell line (C2C12) and primary human mesenchymal stromal cells. In both cell types, HSâbound BMPâ2 and surfaceâimmobilized BMPâ2 significantly prolong SMAD 1/5 phosphorylation, compared to BMPâ2 added to the culture media. Moreover, HSâbound BMPâ2 enhances pâSMAD 1/5 levels in C2C12 cells and reduces noggin antagonistic activity. Thus, grafted HS positively affects BMPâ2 cellular activity. This innovative surface design, which mimics natural interactions of growth factors with ECM components, constitutes a promising candidate for future regenerative medicine applications
Special relativity constraints on the effective constituent theory of hybrids
We consider a simplified constituent model for relativistic
strong-interaction decays of hybrid mesons. The model is constructed using
rules of renormalization group procedure for effective particles in light-front
quantum field theory, which enables us to introduce low-energy phenomenological
parameters. Boost covariance is kinematical and special relativity constraints
are reduced to the requirements of rotational symmetry. For a hybrid meson
decaying into two mesons through dissociation of a constituent gluon into a
quark-anti-quark pair, the simplified constituent model leads to a rotationally
symmetric decay amplitude if the hybrid meson state is made of a constituent
gluon and a quark-anti-quark pair of size several times smaller than the
distance between the gluon and the pair, as if the pair originated from one
gluon in a gluonium state in the same effective theory.Comment: 11 pages, 5 figure
Hybrid Meson Decay Phenomenology
The phenomenology of a newly developed model of hybrid meson decay is
developed. The decay mechanism is based on the heavy quark expansion of QCD and
the strong coupling flux tube picture of nonperturbative glue. A comprehensive
list of partial decay widths of a wide variety of light, , ,
and hybrid mesons is presented. Results which appear approximately
universal are highlighted along with those which distinguish different hybrid
decay models. Finally, we examine several interesting hybrid candidates in
detail.Comment: 37 pages, 2 figures, 6 tables, Revte
- âŠ