23 research outputs found
Helium mixtures in nanotube bundles
An analogue to Raoult's law is determined for the case of a 3He-4He mixture
adsorbed in the interstitial channels of a bundle of carbon nanotubes. Unlike
the case of He mixtures in other environments, the ratio of the partial
pressures of the coexisting vapor is found to be a simple function of the ratio
of concentrations within the nanotube bundle.Comment: 3 pages, no figures, submitted to Phys. Rev. Let
Universality in the partially anisotropic three-dimensional Ising lattice
Using transfer-matrix extended phenomenological renormalization-group methods
the critical properties of spin-1/2 Ising model on a simple-cubic lattice with
partly anisotropic coupling strengths are studied.
Universality of both fundamental critical exponents and is
confirmed. It is shown that the critical finite-size scaling amplitude ratios
, , and
are independent of the lattice anisotropy
parameter . By this for the last above invariant of the
three-dimensional Ising universality class we give the first quantitative
estimate: (shape , periodic boundary
conditions in both transverse directions).Comment: 11 pages in latex; no figure
Monte Carlo with Absorbing Markov Chains: Fast Local Algorithms for Slow Dynamics
A class of Monte Carlo algorithms which incorporate absorbing Markov chains
is presented. In a particular limit, the lowest-order of these algorithms
reduces to the -fold way algorithm. These algorithms are applied to study
the escape from the metastable state in the two-dimensional square-lattice
nearest-neighbor Ising ferromagnet in an unfavorable applied field, and the
agreement with theoretical predictions is very good. It is demonstrated that
the higher-order algorithms can be many orders of magnitude faster than either
the traditional Monte Carlo or -fold way algorithms.Comment: ReVTeX, Request 3 figures from [email protected]
Anisotropic Condensation of Helium in Nanotube Bundles
Helium atoms are strongly attracted to the interstitial channels within a
bundle of carbon nanotubes. The strong corrugation of the axial potential
within a channel can produce a lattice gas system where the weak mutual
attraction between atoms in neighboring channels of a bundle induces
condensation into a remarkably anisotropic phase with very low binding energy.
We estimate the binding energy and critical temperature for 4He in this novel
quasi-one-dimensional condensed state. At low temperatures, the specific heat
of the adsorbate phase (fewer than 2% of the total number of atoms) greatly
exceeds that of the host material.Comment: 8 pages, 3 figures, submitted to PRL (corrected typo in abstract
Wang-Landau simulation for the quasi-one-dimensional Ising model
We revisit the nature of the quasi-one-dimensional Ising model on the basis
of Wang-Landau simulation. We introduce the density of states in the
two-dimensional energy space corresponding to the intra- and inter-chain
directions. We then analyze the interchain coupling dependence of the specific
heat of the anistropic two-dimensional Ising model in the context of the
density of states, and further discuss the size dependences of the peak
temperature. We also discuss the feature of the phase transition in the
three-dimensional case.Comment: 7 pages, 8 figures, to appear in J. Phys. Soc. Jp
Inferring causal molecular networks: empirical assessment through a community-based effort.
It remains unclear whether causal, rather than merely correlational, relationships in molecular networks can be inferred in complex biological settings. Here we describe the HPN-DREAM network inference challenge, which focused on learning causal influences in signaling networks. We used phosphoprotein data from cancer cell lines as well as in silico data from a nonlinear dynamical model. Using the phosphoprotein data, we scored more than 2,000 networks submitted by challenge participants. The networks spanned 32 biological contexts and were scored in terms of causal validity with respect to unseen interventional data. A number of approaches were effective, and incorporating known biology was generally advantageous. Additional sub-challenges considered time-course prediction and visualization. Our results suggest that learning causal relationships may be feasible in complex settings such as disease states. Furthermore, our scoring approach provides a practical way to empirically assess inferred molecular networks in a causal sense
Inferring causal molecular networks: empirical assessment through a community-based effort
It remains unclear whether causal, rather than merely correlational, relationships in molecular networks can be inferred in complex biological settings. Here we describe the HPN-DREAM network inference challenge, which focused on learning causal influences in signaling networks. We used phosphoprotein data from cancer cell lines as well as in silico data from a nonlinear dynamical model. Using the phosphoprotein data, we scored more than 2,000 networks submitted by challenge participants. The networks spanned 32 biological contexts and were scored in terms of causal validity with respect to unseen interventional data. A number of approaches were effective, and incorporating known biology was generally advantageous. Additional sub-challenges considered time-course prediction and visualization. Our results suggest that learning causal relationships may be feasible in complex settings such as disease states. Furthermore, our scoring approach provides a practical way to empirically assess inferred molecular networks in a causal sense
Inferring causal molecular networks: empirical assessment through a community-based effort
Inferring molecular networks is a central challenge in computational biology. However, it has remained unclear whether causal, rather than merely correlational, relationships can be effectively inferred in complex biological settings. Here we describe the HPN-DREAM network inference challenge that focused on learning causal influences in signaling networks. We used phosphoprotein data from cancer cell lines as well as in silico data from a nonlinear dynamical model. Using the phosphoprotein data, we scored more than 2,000 networks submitted by challenge participants. The networks spanned 32 biological contexts and were scored in terms of causal validity with respect to unseen interventional data. A number of approaches were effective and incorporating known biology was generally advantageous. Additional sub-challenges considered time-course prediction and visualization. Our results constitute the most comprehensive assessment of causal network inference in a mammalian setting carried out to date and suggest that learning causal relationships may be feasible in complex settings such as disease states. Furthermore, our scoring approach provides a practical way to empirically assess the causal validity of inferred molecular networks
Integrative molecular characterization of malignant pleural mesothelioma
Malignant pleural mesothelioma (MPM) is a highly lethal cancer of the lining of the chest cavity. To expand our understanding of MPM, we conducted a comprehensive integrated genomic study, including the most detailed analysis of BAP1 alterations to date. We identified histology-independent molecular prognostic subsets, and defined a novel genomic subtype with TP53 and SETDB1 mutations and extensive loss of heterozygosity. We also report strong expression of the immune-checkpoint gene VISTA in epithelioid MPM, strikingly higher than in other solid cancers, with implications for the immune response to MPM and for its immunotherapy. Our findings highlight new avenues for further investigation of MPM biology and novel therapeutic options. SIGNIFICANCE: Through a comprehensive integrated genomic study of 74 MPMs, we provide a deeper understanding of histology-independent determinants of aggressive behavior, define a novel genomic subtype with TP53 and SETDB1 mutations and extensive loss of heterozygosity, and discovered strong expresssion of the immune-checkpoint gene VISTA in epithelioid MPM