The Exponential Map for the Conformal Group 0(2,4)

We present a general method to obtain a closed, finite formula for the exponential map from the Lie algebra to the Lie group, for the defining representation of the orthogonal groups. Our method is based on the Hamilton-Cayley theorem and some special properties of the generators of the orthogonal group, and is also independent of the metric. We present an explicit formula for the exponential of generators of the $SO_+(p,q)$ groups, with $p+q = 6$, in particular we are dealing with the conformal group $SO_+(2,4)$, which is homomorphic to the $SU(2,2)$ group. This result is needed in the generalization of U(1) gauge transformations to spin gauge transformations, where the exponential plays an essential role. We also present some new expressions for the coefficients of the secular equation of a matrix.Comment: 16pages,plain-TeX,(corrected TeX

Developing a Successful Information and Communication Technology Industry: The Role of Venture Capital, Knowledge, and the Government

Study of the factors that have lead to the development of a flourishing information and communication technology (ICT) industry is often based on the Silicon Valley development in the U.S. Given the globaliza- tion of the ICT industry, there is a need to understand the factors which contribute to the development of a successful ICT industry and to determine whether a generic model can be used to gain a better understanding of the forces that shape ICT development in other regions of the world. This study examines the phenomenal growth of the Israeli ICT industry in recent years, growth that is referred to as the “New Silicon Valley.” A generic model for the development of ICT industry is presented. We use the model to compare the develop- ment of the Israeli ICT industry with that of Silicon Valley and with the current state of the Dutch ICT industry. The results indicate that the model holds for both (historical) review of the development of Silicon Valley and for the current state of the Dutch ICT industry. The implications of the findings are discussed

The exponential map for the unitary group SU(2,2)

In this article we extend our previous results for the orthogonal group, $SO(2,4)$, to its homomorphic group $SU(2,2)$. Here we present a closed, finite formula for the exponential of a $4\times 4$ traceless matrix, which can be viewed as the generator (Lie algebra elements) of the $SL(4,C)$ group. We apply this result to the $SU(2,2)$ group, which Lie algebra can be represented by the Dirac matrices, and discuss how the exponential map for $SU(2,2)$ can be written by means of the Dirac matrices.Comment: 10 page

First Report of Satellite Males during Breeding in \u3cem\u3eLeptodactylus latrans\u3c/em\u3e (Amphibia, Anura)

Individual males can adopt alternative mating tactics. The occurrence of satellite males is a common behaviour across anuran taxa (e.g., Lithobates clamitans, Wells, 1977; Anaxyrus cognatus, Krupa, 1989; Dendropsophus ebraccatus, Miyamoto and Cane, 1980; Rhinella crucifer, Forester and Lynken, 1986). Satellite males take peripheral positions to calling males, and adopt alternate mating tactics in an attempt to intercept females that are attracted to calling males (Wells, 2007) to increase their own mating success. Satellite males could have an inexpensive form of mate-locating, avoiding predators, and saving energy (Arak, 1983). Furthermore, this strategy could play an important role in the genetic structure of populations (Lodé and Lesbarrères, 2004)

Assessment of the calling detection probability throughout the day of two invasive populations of bullfrog (Lithobates catesbeianus) in Uruguay

Bullfrog invasion is a major conservation concern in South America, so there is an urgent need to detect and monitor its many invasion foci. Amphibian sampling methods commonly use calling display, specifically the nuptial calls of males. With the aim of obtaining the better day period to sample and monitor Lithobates catesbeianus presence, we recorded its calls at three ponds in two invaded localities in Uruguay (Aceguá, Cerro Largo, and San Carlos, Maldonado) during the reproductive season. Then, we studied the records, obtaining a subsample of calling intensity at the first 5 minutes for each hour. We detected that vocalization intensity remained almost constant between 20:00 and 05:00 h. Detection probability remained high and constant during this period, and then decreased. Therefore, bullfrog displays a constant calling activity during the nights of its reproductive period, even longer than native anurans. This long calling period facilitates its detection during nocturnal sampling

Current status of American bullfrog, Lithobates catesbeianus, invasion in Uruguay and exploration of chytrid infection

The American bullfrog Lithobates catesbeianus is an invasive species that can strongly affect native amphibian communities through competition, predation, or introduction of diseases. This frog has invaded multiple areas in South America, for which niche models predict suitable environments across much of the continent. This paper reveals the state of the invasion of this species in Uruguay and its possible relationship with the chytrid pathogenic fungus, Batrachochytrium dendrobatidis. Surveys at invaded sites were conducted from 2007 to 2015, identified two populations undergoing recent range expansion (one of them exponential), two populations that failed to establish, and a new record in an urban area of the capital city, Montevideo. In all the analysed feral populations, chytridiomycosis was found. Our data suggest that the invasion of L. catesbeianus in Uruguay is at an early stage, with very localized populations, which might allow for the implementation of cost-effective management plans, with eradication constituting a plausible option

American bullfrog (Lithobates catesbeianus) diet in Uruguay compared with other invasive populations in Southern South America

Between 2000-2020, more than ten new populations of the invasive American bullfrog (Lithobates catesbeianus) have been reported in the southern cone of South America. We studied the stomach contents of 126 bullfrogs from a population at an early invasion stage in Uruguay (Acegua, Cerro Largo Department). We observed a rich diet, with extensive prey volume range (1 mm3 to more than 7 000 mm(3)); the most frequent items were Hymenoptera (19.6%), Coleoptera (16.4%), Amphipoda (13.3%), Anura (8.9%) and Heteroptera (8.7%). Despite some overlap, differences were observed in volume (chi(2) = 54.6, p \u3c0.001, d.f. = 2) and prey quantity (F = 8.1, p \u3c0.001, d.f. = 79) between males, females, and juveniles. Juveniles showed significantly higher consumption of terrestrial prey by count (82% of their total ingestion) than adults (29% for males and 32% for females) (chi(2) = 28.5, p \u3c0.001, d.f. = 2). Adults, especially females, showed a high frequency of cannibalism (33% of their total ingestion; chi(2) = 20.9, p \u3c0.001, d.f. = 2). Comparing our data with other bullfrog regional studies, we found great plasticity in trophic habits and differences in the incidence of cannibalism (higher incidence in the populations of Acegua, Uruguay, and Buenos Aires, Argentina). These differences could be related to local biodiversity, but also could be affected by the invasion phase. Cannibalism frequency was higher in small bullfrog populations, where it could be favoring the establishment success. This shift in foraging strategies during the invasion process had been insufficiently evaluated in amphibians. Knowing the ecological determinants for the invasion by bullfrogs can be useful to the development of management strategies

DNA Methylation Differences in Monozygotic Twin Pairs Discordant for Schizophrenia Identifies Psychosis Related Genes and Networks

Background Despite their singular origin, monozygotic twin pairs often display discordance for complex disorders including schizophrenia. It is a common (1%) and often familial disease with a discordance rate of ~50% in monozygotic twins. This high discordance is often explained by the role of yet unknown environmental, random, and epigenetic factors. The involvement of DNA methylation in this disease appears logical, but remains to be established. Methods We have used blood DNA from two pairs of monozygotic twins discordant for schizophrenia and their parents in order to assess genome-wide methylation using a NimbleGen Methylation Promoter Microarray. Results The genome-wide results show that differentially methylated regions (DMRs) exist between members representing discordant monozygotic twins. Some DMRs are shared with parent(s) and others appear to be de novo. We found twenty-seven genes affected by DMR changes that were shared in the affected member of two discordant monozygotic pairs from unrelated families. Interestingly, the genes affected by pair specific DMRs share specific networks. Specifically, this study has identified two networks; “cell death and survival” and a “cellular movement and immune cell trafficking”. These two networks and the genes affected have been previously implicated in the aetiology of schizophrenia. Conclusions The results are compatible with the suggestion that DNA methylation may contribute to the discordance of monozygotic twins for schizophrenia. Also, this may be accomplished by the direct effect of gene specific methylation changes on specific biological networks rather than individual genes. It supports the extensive genetic, epigenetic and phenotypic heterogeneity implicated in schizophrenia

Exchange-correlation vector potentials and vorticity-dependent exchange-correlation energy densities in two-dimensional systems

We present a new approach how to calculate the scalar exchange-correlation potentials and the vector exchange-correlation potentials from current-carrying ground states of two-dimensional quantum dots. From these exchange-correlation potentials we derive exchange-correlation energy densities and examine their vorticity (or current) dependence. Compared with parameterizations of current-induced effects in literature we find an increased significance of corrections due to paramagnetic current densities.Comment: 5 figures, submitted to PR

Early skewed differentiation and PD-1 expression in CD4+ cells relate to immune dysfunction and viral persistence in individuals living with HIV 1 year post-cART initiation

Achieving HIV functional cure is a priority. Strategies such as adoptive cell transfer have been assayed, without success yet mainly due to immune dysfunctions observed among individuals. Samples from 25 HIV+ subjects were collected at diagnosis (baseline sample, BSL) and one year post-cART initiation (post- cART ). At BSL, bulk and HIV-specific CD4 phenotype (CD45RO , CCR 7, CD95 and PD1 expression) was assessed by flow cytometry after a short stimulation with HIV peptides. Also, proportion of CD4+/HLA-DR+/ CD38+ cells was measured. At post-cART , HIV-specific CD8TC s were obtained after 2-week expansion with peptides. Phenotype and antiviral activity (VIA and VITA L assays) were evaluated post-expansion. Plasma CXCL10 (IP-10) was assessed by ELISA. Cell-associated HIV DNA (total and integrated) and unspliced (US) and multiply-spliced (MS) RNA were quantified by real-time PCR. Non-parametric statistics were applied. Early CD4TC exhaustion, elevated activation and inadequate differentiation seem to be associated with viral persistence, inflammation, as well as with the phenotype and antiviral capacity of HIV-specific CD8TC s that persist one year after cART is initiated. These parameters could serve as predictors of CD8TC function on treated subjects.Fil: Salido, Jimena Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas en Retrovirus y Sida; ArgentinaFil: Czernikier, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas en Retrovirus y Sida; ArgentinaFil: Trifone, César Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas en Retrovirus y Sida; ArgentinaFil: Figueroa, M. I.. Fundación Huésped; ArgentinaFil: Salomon, Horacio Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas en Retrovirus y Sida; ArgentinaFil: Cahn, P.. Fundación Huésped; ArgentinaFil: Sued, O.. Fundación Huésped; ArgentinaFil: Laufer, Natalia Lorna. Gobierno de la Ciudad de Buenos Aires. Hospital General de Agudos "Juan A. Fernández"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas en Retrovirus y Sida; ArgentinaFil: Ghiglione, Yanina Alexandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas en Retrovirus y Sida; ArgentinaFil: Turk, Gabriela Julia Ana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas en Retrovirus y Sida; Argentin