Phase transitions and noise crosscorrelations in a model of directed polymers in a disordered medium

We show that effective interactions mediated by disorder between two directed polymers can be modelled as the crosscorrelation of noises in the Kardar-Parisi-Zhang (KPZ) equations satisfied by the respective free energies of these polymers. When there are two polymers, disorder introduces attractive interactions between them. We analyze the phase diagram in details and show that these interactions lead to new phases in the phase diagram. We show that, even in dimension $d=1$, the two directed polymers see the attraction only if the strength of the disorder potential exceeds a threshold value. We extend our calculations to show that if there are $m$ polymers in the system then $m$-body interactions are generated in the disorder averaged effective free energy.Comment: To appear in Phys. Rev. E(2000

Short-range correlations in two-nucleon knockout reactions

A theory of short-range correlations in two-nucleon removal due to elastic breakup (diffraction dissociation) on a light target is developed. Fingerprints of these correlations will appear in momentum distributions of back-to-back emission of the nucleon pair. Expressions for the momentum distributions are derived and calculations for reactions involving stable and unstable nuclear species are performed. The signature of short-range correlations in other reaction processes is also studied.Comment: Nuclear Physics A, in pres

Optimal low-thrust trajectories to asteroids through an algorithm based on differential dynamic programming

In this paper an optimisation algorithm based on Differential Dynamic Programming is applied to the design of rendezvous and fly-by trajectories to near Earth objects. Differential dynamic programming is a successive approximation technique that computes a feedback control law in correspondence of a fixed number of decision times. In this way the high dimensional problem characteristic of low-thrust optimisation is reduced into a series of small dimensional problems. The proposed method exploits the stage-wise approach to incorporate an adaptive refinement of the discretisation mesh within the optimisation process. A particular interpolation technique was used to preserve the feedback nature of the control law, thus improving robustness against some approximation errors introduced during the adaptation process. The algorithm implements global variations of the control law, which ensure a further increase in robustness. The results presented show how the proposed approach is capable of fully exploiting the multi-body dynamics of the problem; in fact, in one of the study cases, a fly-by of the Earth is scheduled, which was not included in the first guess solution

Aflibercept in the Treatment of Metastatic Colorectal Cancer

Colorectal cancer is the third most common cancer in the US. In recent decades, an improved understanding of the role of the angiogenesis pathway in colorectal cancer has led to advancements in treatment. Bevacizumab has been shown to improve the progression-free survival and overall survival when combined with cytotoxic chemotherapy in patients with metastatic colorectal cancer, and at present is the only antiangiogenesis agent approved for the treatment of this cancer. Aflibercept is a novel angiogenesis-targeting agent, and has demonstrated efficacy in treating metastatic colorectal cancer in a recent randomized Phase III trial. Here we review the role of angiogenesis in the tumorigenesis of colorectal cancer, strategies for targeting angiogenesis, and the clinical development of aflibercept

Hard-core Yukawa model for two-dimensional charge stabilized colloids

The hyper-netted chain (HNC) and Percus-Yevick (PY) approximations are used to study the phase diagram of a simple hard-core Yukawa model of charge-stabilized colloidal particles in a two-dimensional system. We calculate the static structure factor and the pair distribution function over a wide range of parameters. Using the statics correlation functions we present an estimate for the liquid-solid phase diagram for the wide range of the parameters.Comment: 7 pages, 9figure

Different Types of Door-Opening Motions as Contributing Factors to Containment Failures in Hospital Isolation Rooms

10.1371/journal.pone.0066663PLoS ONE86-POLN

W=0 Pairing in (N,N)(N,N) Carbon Nanotubes away from Half Filling

We use the Hubbard Hamiltonian $H$ on the honeycomb lattice to represent the valence bands of carbon single-wall $(N,N)$ nanotubes. A detailed symmetry analysis shows that the model allows W=0 pairs which we define as two-body singlet eigenstates of $H$ with vanishing on-site repulsion. By means of a non-perturbative canonical transformation we calculate the effective interaction between the electrons of a W=0 pair added to the interacting ground state. We show that the dressed W=0 pair is a bound state for resonable parameter values away from half filling. Exact diagonalization results for the (1,1) nanotube confirm the expectations. For $(N,N)$ nanotubes of length $l$, the binding energy of the pair depends strongly on the filling and decreases towards a small but nonzero value as $l \to \infty$. We observe the existence of an optimal doping when the number of electrons per C atom is in the range 1.2$\div$1.3, and the binding energy is of the order of 0.1 $\div$ 1 meV.Comment: 16 pages, 6 figure

Early age hydration and application of blended magnesium potassium phosphate cements for reduced corrosion of reactive metals

Magnesium potassium phosphate cements (MKPC) were investigated to determine their efficacy towards retardation of reactive uranium metal corrosion. Optimised low-water content, fly ash (FA) and blast furnace slag (BFS) blended MKPC formulations were developed and their fluidity, hydration behaviour, strength and phase assemblage investigated. In-situ time resolved synchrotron powder X-ray diffraction was used to detail the early age (~60 h) phase assemblage development and hydration kinetics, where the inclusion of BFS was observed to delay the formation of struvite-K by ~14 h compared to FA addition (~2 h). All samples set within this period, suggesting the possible formation of a poorly crystalline binding phase prior to struvite-K crystallisation. Long-term corrosion trials using metallic uranium indicated that MKPC systems are capable of limiting uranium corrosion rates (reduced by half), when compared to a UK nuclear industry grout, which highlights their potential application radioactive waste immobilisation

Oxygen partial pressure dependence of magnetic, optical and magneto-optical properties of epitaxial cobalt-substituted SrTiO3 films

Cobalt-substituted SrTiO3 films (SrTi0.70Co0.30O3-δ) were grown on SrTiO3 substrates using pulsed laser deposition under oxygen pressures ranging from 1 μTorr to 20 mTorr. The effect of oxygen pressure on structural, magnetic, optical, and magneto-optical properties of the films was investigated. The film grown at 3 μTorr has the highest Faraday rotation (FR) and magnetic saturation moment (Ms). Increasing oxygen pressure during growth reduced Ms, FR and optical absorption in the nearinfrared. This trend is attributed to decreasing Co2+ ion concentration and oxygen vacancy concentration with higher oxygen partial pressure during growth. © 2015 Optical Society of America