Polarization-dependence of palladium deposition on ferroelectric lithium niobate (0001) surfaces

We investigate the effect of ferroelectric polarization direction on the geometric properties of Pd deposited on the positive and negative surfaces of LiNbO$_3$ (0001). We predict preferred geometries and diffusion properties of small Pd clusters using density functional theory, and use these calculations as the basis for kinetic Monte Carlo simulations of Pd deposition on a larger scale. Our results show that on the positive surface, Pd atoms favor a clustered configuration, while on the negative surface, Pd atoms are adsorbed in a more dispersed pattern due to suppression of diffusion and agglomeration. This suggests that the effect of LiNbO$_3$ polarization direction on the catalytic activity of Pd [J. Phys. Chem. \textbf{88}, 1148 (1984)] is due, at least in part, to differences in adsorption geometry. Further investigations using these methods can aid the search for catalysts whose activities switch reversibly with the polarization of their ferroelectric substrates

Adolescent beliefs about antisocial behavior : mediators and moderators of links with parental monitoring and attachment

The current study examined whether parental monitoring and attachment were related to adolescent beliefs about antisocial acts, with temperament, gender, and age considered as potential moderators. A total of 7135 adolescents, aged 14-18 years, completed selfreport measures of antisocial beliefs, parental monitoring, attachment security, and temperament. Results indicate that both attachment security and parental monitoring are associated with adolescent beliefs about antisocial behaviour. It also appears that the two aspects of parenting are complementary, in that a secure attachment relationship is associated with greater parental monitoring knowledge, which in turn is linked with a lower tolerance for antisocial behaviour. However, the relations between these aspects of parenting and beliefs about antisocial acts depended on the young people’s characteristics, with some results varying by age, gender and temperament. Implications for future research and parent-focused interventions to prevent antisocial beliefs and behaviour are discussed.peer-reviewe

Eliminating Acute Myeloid Leukemia Stem Cells by Targeting the Niche Microenviromnent: Co-Inhibition of TNF/IL1- JNK and NF-κb

Leukemia Stem Cells (LSCs) from Acute Myeloid Leukemia (AML) require the activity of the transcription factor NF-kB to maintain stemness and drive tumor formation. Blocking NF-kB can preferentially eliminate LSCs in vitro with minimal effects on healthy Hematopoietic Stem and Progenitor Cells (HSPCs), making NF-kB a compelling target for anti-leukemia therapies. However, blocking NF-kB in vivo can only extend survival for a short period of time before transplanted mice succumb to the disease. I propose this is due to components of the in vivo niche supporting LSC survival and compensating for the inhibition of NF-kB. I observed patients with partially differentiated blast-like AML (subtypes M3, M4, and M5) have significantly elevated levels of pro-inflammatory cytokines TNFa and IL-1a/b; (TNF and IL1) circulating in their peripheral blood. Further study revealed these cytokines are primarily produced by LSCs because such cells express several times more of TNF and IL1 than their healthy tissue counterparts. I found that TNF and IL1 stimulate the growth and expansion of LSCs while inducing cell death in HSPCs. Also, LSC-conditioned media alone is sufficient to drive apoptosis/necroptosis in HSPCs that can be prevented by blocking TNF and IL1, suggesting a mechanism for hematopoietic repression commonly observed in AML cases. TNF and IL1 drive their pro-inflammatory effects on target cells through activation of cellular signaling networks. Both TNF and IL1 are potent activators of NF-kB in almost all cells studied, connecting the ability of these cytokines to drive LSC growth with the need of NF-kB for survival. In addition, TNF and IL1 also stimulate activation of JNK signaling which operates in parallel to NF-kB in LSCs and HSPCs. I found that JNK stimulation results in cell death in HSPCs by subsequent inactivation of pro-survival Bcl-2 family proteins by phosphorylation. However, LSCs convert JNK-mediated cell death signals into proliferation/survival signals by both limiting the signal duration to \u3c60 min through dephosphorylation by Map Kinase Phosphatase 5, and also by upregulating JNK\u27s nuclear target c-Jun. Such short duration of JNK activation correlates to activation of JNK\u27s nuclear targets without activating the death signal. I determined that concurrent inhibition of NF-kB and JNK has two major effects: (1) combined inhibition specifically targets LSCs in vitro and in vivo, and (2) the toxicity in healthy HSPCs due to loss of NF-kB signaling is mediated by JNK, making the combined treatment protective. I can substantially increase survival in AML-transplanted mice if they are treated with combination of NF-kB and JNK inhibition in vivo. I can further extend survival in leukemic mice when I treat with blockers to upstream pro-inflammatory cytokines: anti-TNF, anti-IL1, and NF-kB inhibitor. These data provide a strong rationale to treat AML patients by combined inhibition of both TNF/IL1- JNK and NF-kB signaling

Rooting out letters:octagonal symbol alphabets and algebraic number theory

It is widely expected that NMHV amplitudes in planar, maximally supersymmetric Yang-Mills theory require symbol letters that are not rationally expressible in terms of momentum-twistor (or cluster) variables starting at two loops for eight particles. Recent advances in loop integration technology have made this an `experimentally testable' hypothesis: compute the amplitude at some kinematic point, and see if algebraic symbol letters arise. We demonstrate the feasibility of such a test by directly integrating the most difficult of the two-loop topologies required. This integral, together with its rotated image, suffices to determine the simplest NMHV component amplitude: the unique component finite at this order. Although each of these integrals involve algebraic symbol alphabets, the combination contributing to this amplitude is---surprisingly---rational. We describe the steps involved in this analysis, which requires several novel tricks of loop integration and also a considerable degree of algebraic number theory. We find dramatic and unusual simplifications, in which the two symbols initially expressed as almost ten million terms in over two thousand letters combine in a form that can be written in five thousand terms and twenty-five letters.Comment: 25 pages, 4 figures; detailed results available as ancillary file

Embedding Feynman integral (Calabi-Yau) geometries in weighted projective space

It has recently been demonstrated that Feynman integrals relevant to a wide range of perturbative quantum field theories involve periods of Calabi-Yaus of arbitrarily large dimension. While the number of Calabi-Yau manifolds of dimension three or higher is considerable (if not infinite), those relevant to most known examples come from a very simple class: degree-$2k$ hypersurfaces in $k$-dimensional weighted projective space $\mathbb{WP}^{1,\ldots,1,k}$. In this work, we describe some of the basic properties of these spaces and identify additional examples of Feynman integrals that give rise to hypersurfaces of this type. Details of these examples at three and four loops are included as ancillary files to this work.Comment: 44 pages, 31 figures; detailed examples given in ancillary file. Updated to reflect revisions for publicatio

2006 SQ372: A Likely Long-Period Comet from the Inner Oort Cloud

We report the discovery of a minor planet (2006 SQ372) on an orbit with a perihelion of 24 AU and a semimajor axis of 796 AU. Dynamical simulations show that this is a transient orbit and is unstable on a timescale of 200 Myrs. Falling near the upper semimajor axis range of the scattered disk and the lower semimajor axis range of the Oort Cloud, previous membership in either class is possible. By modeling the production of similar orbits from the Oort Cloud as well as from the scattered disk, we find that the Oort Cloud produces 16 times as many objects on SQ372-like orbits as the scattered disk. Given this result, we believe this to be the most distant long-period comet ever discovered. Furthermore, our simulation results also indicate that 2000 OO67 has had a similar dynamical history. Unaffected by the "Jupiter-Saturn Barrier," these two objects are most likely long-period comets from the inner Oort Cloud

Safety assessment of the process ‘PEGRA-V’, based on Starlinger IV+® technology, used to recycle post-consumer PET into food contact materials

Publisher PD

Safety assessment of the process ‘Plastienvase’, based on EREMA Basic technology, used to recycle post-consumer PET into food contact materials

Publisher PD