Computation of H→ggH\to gg in FDH and DRED: renormalization, operator mixing, and explicit two-loop results

The $H\to gg$ amplitude relevant for Higgs production via gluon fusion is computed in the four-dimensional helicity scheme (FDH) and in dimensional reduction (DRED) at the two-loop level. The required renormalization is developed and described in detail, including the treatment of evanescent $\epsilon$-scalar contributions. In FDH and DRED there are additional dimension-5 operators generating the $H g g$ vertices, where $g$ can either be a gluon or an $\epsilon$-scalar. An appropriate operator basis is given and the operator mixing through renormalization is described. The results of the present paper provide building blocks for further computations, and they allow to complete the study of the infrared divergence structure of two-loop amplitudes in FDH and DRED

SCET approach to regularization-scheme dependence of QCD amplitudes

We investigate the regularization-scheme dependence of scattering amplitudes in massless QCD and find that the four-dimensional helicity scheme (FDH) and dimensional reduction (DRED) are consistent at least up to NNLO in the perturbative expansion if renormalization is done appropriately. Scheme dependence is shown to be deeply linked to the structure of UV and IR singularities. We use jet and soft functions defined in soft-collinear effective theory (SCET) to efficiently extract the relevant anomalous dimensions in the different schemes. This result allows us to construct transition rules for scattering amplitudes between different schemes (CDR, HV, FDH, DRED) up to NNLO in massless QCD. We also show by explicit calculation that the hard, soft and jet functions in SCET are regularization-scheme independent.Comment: 46 pages, 6 figure

El capital intelectual concepto-valuación y registro contable

Desde hace mucho tiempo, pero incentivado a partir de los sobre precios abonados por los compradores de empresas dedicadas a los negocios relacionados con la informática, que pusieron de manifiesto las enormes diferencias entre esos precios y el valor contable registrado, los estudiosos de nuestras temáticas tomaron noticias del denominado activo intangible, comenzando a interrogarse con respecto a algunas cuestiones que fueron adquiriendo importancia relevante. Estas cuestiones, parten de un convencimiento aceptado por todos. La economía de lo intangible o nueva economía, va ganando posiciones, los activos más valiosos son los de naturaleza intangible, por lo que resulta esencial hacerlos visibles, a pesar del problema que representa su valuación, y, eventualmente, su registración contable. Es decir, el acuerdo es general, no así en lo referente a la valuación de esos intangibles y la registración contable de los mismos. Enumeremos algunas de ellas, sin la pretensión de considerarlas a todas, salvo las que a nuestro criterio, son las más relevantes. Conceptualmente. ¿Cuáles son las diferencias entre el denominado Fondo de Comercio y también Valor Llave que suscitan este interés particular por el Activo Intangible? ¿Por qué algunos autores lo denominan Capital Intangible en tanto otros lo designan como Capital Intelectual? ¿El capital humano es solo una parte del capital intangible o puede ser considerado como el todo? ¿Si el capital tangible como una inversión goza del principio formulado por el costo de oportunidad, porqué ese mismo principio no se le asigna al capital humano? ¿Y con respecto al capital humano, no es necesario considerar su aporte ex ante de su incorporación a la empresa con respecto al capital ex post adquirido como resultado del aporte de los sistemas de información y de la capacitación que le brindan la práctica y el apoyo empresarial? Valuación. ¿Por qué existen tantas fórmulas dedicadas a la valuación del capital intangible sin que ninguna tenga una aceptación general que le de la suficiente validez para ser utilizada para su registro contable?. Finalmente, en el caso de registrar contablemente el capital intangible, ¿qué efectos produciría en lo referente a los costos, o sería absolutamente neutra? Registración contable. ¿Es absolutamente indispensable el registro contable del capital intangible?.Fil: Visconti, Rubén A. Universidad Nacional de Mar del Plata. Facultad de Ciencias Económicas y Sociales; Argentina

Exploiting an HMAC-SHA-1 optimization to speed up PBKDF2

PBKDF2 is a well-known password-based key derivation function. In order to slow attackers down, PBKDF2 introduces CPU-intensive operations based on an iterated pseudorandom function (in our case HMAC-SHA-1). If we are able to speed up a SHA-1 or an HMAC implementation, we are able to speed up PBKDF2-HMAC-SHA-1. This means that a performance improvement might be exploited by regular users and attackers. Interestingly, FIPS 198-1 suggests that it is possible to precompute first message block of a keyed hash function only once, store such a value and use it each time is needed. Therefore the computation of first message block does not contribute to slowing attackers down, thus making the computation of second message block crucial. In this paper we focus on the latter, investigating the possibility to avoid part of the HMAC-SHA-1 operations. We show that some CPU-intensive operations may be replaced with a set of equivalent, but less onerous, instructions. We identify useless XOR operations exploiting and extending Intel optimizations, and applying the Boyar-Peralta heuristic. In addition, we provide an alternative method to compute the SHA-1 message scheduling function and explain why attackers might exploit these findings to speed up a brute force attack against PBKDF2

Update about "minimally verbal" children with autism spectrum disorder.

OBJECTIVE: To review clinical and neurobiological features of minimally verbal children with autism spectrum disorder. DATA SOURCE: We carried out a narrative review using the PubMed database. We considered the following search terms combined through the Boolean operator "AND": "autism spectrum disorder"; "minimally verbal." DATA SYNTHESIS: To date, there is no shared definition of minimally verbal children with autism spectrum disorder. The heterogeneity in intellectual functioning and in linguistic abilities among these individuals suggests there is no single mechanism underlying their difficulties in learning to speak. However, the reasons why these children do not speak and the biological markers that can identify them are still unknown. Language impairment in these children can lead to several unfavorable consequences, including behavior problems (such as self-aggression, hetero-aggression, and property destruction), poorer daily living and social skills. Psychiatric comorbidities (including attention deficit/hyperactivity disorder, specific phobias, and compulsions) consist in a serious problem related to the lack of verbal language in individuals with autism spectrum disorder. Although in the literature there are very few evidence-based results, several findings suggest that an alternative and augmentative communication intervention, creating an extra-verbal communication channel, may be effective in these individuals. CONCLUSIONS: The exact definition, clinical characteristics, associated disorders, etiology, and treatment of minimally verbal subjects with autism spectrum disorder must still be further studied and understood