Hopf Algebras of Heap Ordered Trees and Permutations

It is known that there is a Hopf algebra structure on the vector space with basis all heap-ordered trees. We give a new bialgebra structure on the space with basis all permutations and show that there is a direct bialgebra isomorphism between the Hopf algebra of heap-ordered trees and the bialgebra of permutations.Comment: 10 pages LaTeX, minor revisio

New Physics Effects in B→K(∗)ννB \to K^(*) \nu \nu Decays

We present a model-independent analysis of rare B decays, $B \to K^{(*)} \nu \nu$. The effect of possible new physics is written in terms of dimension-6 four-fermi interactions. The lepton number violating scalar- and tensor-type interactions are included, and they induce $B \to K^{(*)} \nu \nu ({\bar \nu} {\bar \nu})$ decays. We show systematically how the branching ratios and missing mass-squared spectrum depend on the coefficients of the four-fermi interactions.Comment: 20 pages with 7 figure

The realization of input-output maps using bialgebras

The theory of bialgebras is used to prove a state space realization theorem for input/output maps of dynamical systems. This approach allows for the consideration of the classical results of Fliess and more recent results on realizations involving families of trees. Two examples of applications of the theorum are given

MFV SUSY: A Natural Theory for R-Parity Violation

We present an alternative approach to low-energy supersymmetry. Instead of imposing R-parity we apply the minimal flavor violation (MFV) hypothesis to the R-parity violating MSSM. In this framework, which we call MFV SUSY, squarks can be light and the proton long lived without producing missing energy signals at the LHC. Our approach differs from that of Nikolidakis and Smith in that we impose holomorphy on the MFV spurions. The resulting model is highly constrained and R-parity emerges as an accidental approximate symmetry of the low-energy Lagrangian. The size of the small R-parity violating terms is determined by the flavor parameters, and in the absence of neutrino masses there is only one renormalizable R-parity violating interaction: the baryon-number violating $\bar{u}\bar{d}\bar{d}$ superpotential term. Low energy observables (proton decay, dinucleon decay and $n-\bar{n}$ oscillation) pose only mild constraints on the parameter space. LHC phenomenology will depend on whether the LSP is a squark, neutralino, chargino or slepton. If the LSP is a squark it will have prompt decays, explaining the non-observation of events with missing transverse energy at the LHC.Comment: 41 pages, 14 figures; v3: minor corrections, matches published versio

Electrical and infrared properties of thin niobium microbolometers near T(sub c)

Niobium microbolometers approximately 1 micron wide x 2 micron long x 10 nm thick have been integrated at the feeds of equiangular spiral antennas made of 200 nm thick Nb. The device's current-voltage characteristics and infrared responsivity as a function of DC bias voltage were measured over a range of temperature spanning approximately plus or minus 2 percent around T(sub c). The greatest voltage responsivity occurs well below T(sub c), in a regime where the I-V curve is significantly hysteretic due to self-heating and resembles the I-V curve of a superconducting microbridge

Coping with the editorial process: considerations for early–career biologists

Lidiar con el proceso editorial: consideraciones para biólogos en la fase inicial de su carrera En el presente enensayo se describen algunos aspectos de la interacción entre los autores, los revisores y los editores, con el objetivo de ayudar a los biólogos en la fase inicial de su carrera a navegar por el proceso de publicación. Múltiples autores y editores han señalado las dificultades actuales para encontrar revisores de calidad que revisen los manuscritos y, como consecuencia, es posible que esté aumentando la frecuencia de rechazos debido a revisiones sin conocimiento de causa y erróneos. Se sugieren varias estrategias para lidiar con: 1) el rechazo de manuscritos por los editores sin una revisión; 2) los editores que informan de los comentarios de los revisores, pero no formulan observaciones al respecto; 3) las revisiones que parecen desinformadas o idiosincrásicas; y 4) los comentarios que sugieren cambios de estilo en lugar de cambios sustantivos. La clave de toda buena estrategia para tratar con los editores y los revisores consiste en asegurarse de que la interacción sea cordial y mantenga un alto grado de objetividad respecto de las críticas. Además, las estrategias concretas que un autor utiliza para responder a los comentarios estilísticos y sustantivos de los editores dependerán de su experiencia y, tal vez, de su reputación en el sector. Las técnicas que aquí se sugieren deberían servir para estimular el debate sobre algunos problemas de nuestro sector y aumentar la probabilidad de que se acepte un buen manuscrito sometido para su publicación.In this essay I describe aspects of the interactions between authors, reviewers and editors with the goal of helping early–career biologists navigate the publication process. Multiple authors and editors have commented on the current difficulties of obtaining quality referees for manuscript reviews, and as a consequence, the frequencies of rejections based on uninformed or erroneous reviews, may be increasing. I suggest a variety of strategies for dealing with: 1) manuscript rejections by editors without review, 2) editors who report but do not comment on reviewer comments, 3) reviews that appear to be uninformed or idiosyncratic, and 4) comments suggesting stylistic revisions rather than substantive ones. The key to any successful strategy for dealing with editors and referees involves ensuring the interaction remains civil and retains a high level of objectivity regarding criticism. In addition, the specific strategies that an author uses to respond to stylistic and substantive editorial comments will depend on their experience and perhaps, reputation in the field. The techniques suggested herein should serve to stimulate discussion of some problems in our field and also increase the probability of acceptance of a worthy manuscript submitted for publication.Lidiar con el proceso editorial: consideraciones para biólogos en la fase inicial de su carrera En el presente enensayo se describen algunos aspectos de la interacción entre los autores, los revisores y los editores, con el objetivo de ayudar a los biólogos en la fase inicial de su carrera a navegar por el proceso de publicación. Múltiples autores y editores han señalado las dificultades actuales para encontrar revisores de calidad que revisen los manuscritos y, como consecuencia, es posible que esté aumentando la frecuencia de rechazos debido a revisiones sin conocimiento de causa y erróneos. Se sugieren varias estrategias para lidiar con: 1) el rechazo de manuscritos por los editores sin una revisión; 2) los editores que informan de los comentarios de los revisores, pero no formulan observaciones al respecto; 3) las revisiones que parecen desinformadas o idiosincrásicas; y 4) los comentarios que sugieren cambios de estilo en lugar de cambios sustantivos. La clave de toda buena estrategia para tratar con los editores y los revisores consiste en asegurarse de que la interacción sea cordial y mantenga un alto grado de objetividad respecto de las críticas. Además, las estrategias concretas que un autor utiliza para responder a los comentarios estilísticos y sustantivos de los editores dependerán de su experiencia y, tal vez, de su reputación en el sector. Las técnicas que aquí se sugieren deberían servir para estimular el debate sobre algunos problemas de nuestro sector y aumentar la probabilidad de que se acepte un buen manuscrito sometido para su publicación

The analysis and design of transonic two-element airfoil systems

The multiphase effort in the development of tools for the analysis and design of two-element airfoil systems, that is, airfoils with a slat or a flap at transonic speeds is described. The first phase involved the development of a method to compute the inviscid flow over such configurations. In the second phase the inviscid code was coupled to a boundary layer calculation program in order to compute the loss in performance due to viscous effects. An inverse code that constructs the airfoil system corresponding to a desired pressure distribution is described