The Automorphism Group of Certain Higher Degree Forms

We consider symmetric d-linear forms of dimension n over an algebraically closed field k of characteristic 0. The "center" of a form is the analogous of the space of symmetric matrices of a bilinear form. For d>2 the center is a commutative subalgebra of $\mathbf{M}_n(k)$. The automorphism group of the form acts naturally on the center. We give a description of this group via this action.Comment: Title changed. Final version, to appear in appear in Journal of Pure and Applied Algebr

The biochemical analysis of southern African rhinoceros populations

The drastic decline in the numbers of the five extant species of rhinoceroses world-wide, mainly as a result of poaching, have placed these species in imminent danger of extinction. This emphasizes the need to understand the relationships among the different species of rhinoceros. The advances in molecular biology have allowed the application of DNA-based genetic techniques to address a number of aspects of rhinoceros biology which have both academic interest and practical value to conservation management. There are four aspects to this study: Firstly, restriction endonuclease maps of mitochondrial DNA were constructed to estimate the time of divergence of Diceros bicornis (black rhinoceros) and Ceratotherium simum (white rhinoceros) from their common ancestor. Secondly, a population genetic study of the relationships among four subspecies of D. bicornis. Thirdly, the application of DNA fingerprinting to examine the intra- and inter-population relatedness in D. bicornis populations. Fourthly, a practical application of PCR to identify the origin of an unknown sample of DNA

El sentido de la televisión universitaria

Indexación: Revista UNA

Caliciviruses and Foodborne Gastroenteritis, Chile

Human caliciviruses caused 45% of 55 gastroenteritis outbreaks occurring in Santiago, Chile, during 2000–2003. Outbreaks affected ≤99 persons, occurred most commonly in the home, and were associated with seafood consumption. Thirteen outbreak strains sequenced were noroviruses, including 8 GII, 2 GI, and 3 belonging to a novel genogroup

The Great Moderation and the New Business Cycle

There is a new approach to modeling business cycles that is gaining acceptance. It appears that there is good evidence that this approach may have a great deal to offer in understanding the causes and processes of major economic business cycles associated with financial crisis. This paper does not intend to define a mathematical model but instead describes the ideas and theories behind this new approach. In addition, this paper addresses a few of the unique challenges officials within the United States face with the current global crisis. The new approach has at its core the belief that the structure of our current economy, as well as many European economies, has changed significantly. Starting around 1983-1985 a structural break occurred that resulted in a period where changes in GDP, consumption and inflation ceased to experience high volatility. This period has been dubbed “The Great Moderation” and it is significant. The standard deviation during the years 1985-2004 was but one-half the standard deviation of the quarterly growth rate of real gross domestic product between the years 1960-1984. A variety of hypothesis for this period has been put forth of which will not be discussed in this paper. More importantly here, is that these new economies are subject to business cycles that are endogenous in nature and are highly correlated with financial crisis. It is believed that these new economies have specific characteristics that generate these financial business cycles. These cycles are not triggered by exogenous supply or demand shocks that throw an economy off of a steady state but instead are an endogenous force within the gears of the system itself that creates imbalances that can build up without any noticeable increase in inflation - the traditional parameter typically used to monitor imbalances. The main characteristic of this new era of Great Moderation is rapidly rising growth coupled with low and stable prices which is highly correlated with an increase in the probability of episodes of financial instability (Borio 2003). In fact, within these new economies inflation shows up first as excess demand within credit aggregates and asset prices rather than in the traditional goods and services markets. This means that a financial crisis could occur without inflation ever having occurred within the broader economy. If asset bubbles are left unattended the resulting implosion of the bubbles can create virulent deflationary episodes. And it is the unwinding of the financial imbalances caused by the bubbles that are the source of financial instability. Note that according to this model, it is not a sudden decline in inflation brought on by a contraction in the money supply that triggers a crisis as is often argued (for example Friedman and Schwartz 1963). So, minimizing the deflationary impact will not stop the necessary unwinding and required rebalancing. There are many parameters that have been used in developing predictive models that anticipate a financial crisis. A few leading indicators that may warn of a growing financial crisis are: 1. Widening Credit gaps and rapidly rising assets values (equities, real estate- inelastic assets) 2. Over confidence / ‘exuberance’ coupled with faith in central bankers anti-inflationary commitments 3. Misalignments in intertemporal consumption, savings and investment decisions 4. Output gaps 5. Currency exchange rates / imbalance in global savings Again, this paper does not intend to define a model but instead simply lays out the ideas and theories behind this new modeling approach. This paper will first compare the traditional to the new modeling approach by first describing the economic environment that creates the business cycle. Secondly it will compare the two paradigms and explain how each generates different questions and answers in monitoring and explaining economic stability. Finally, I touch on a few of the unique challenges facing our current crisis within the United States

Park use, perceived park proximity, and neighborhood characteristics: Evidence from 11 cities in Latin America

This study examines how park use may be associated with perceived park proximity, neighborhood-built environment and perceived social disorder in Latin American cities. The study uses self-reported data from the 2016 CAF survey, including 7,970 urban residents from 11 cities across Latin America. Results show positive graded associations between perceived park proximity and use, holding all others constant. Additional factors that were found to be associated with park use are neighborhood formality and related built-environment characteristics, including paved streets and sidewalks. Park use was mostly unrelated to perceived social disorder, with the exception of indigence, with which it is was positively associated. Stronger associations between park proximity and use were observed among those who reported higher prevalence of indigence or begging in their household block. These findings stress the importance of perceived park proximity in enhancing their use in urban Latin America, and challenge the role of social disorder and crime as a barrier for park use

Development of a DNA marker by minisatellite associated sequence amplification (MASA) from the endangered Indian rhino (Rhinoceros unicornis)

Rhinoceroses are highly endangered species and their protection warrants immediate remedial measures. Development of DNA markers is envisaged to complement global efforts of the conservation of these extant animals. Minisatellite associated sequence amplification (MASA) of DNA from Indian rhinoceros (Rhinoceros unicornis) and three sub-species of South African black rhinoceros (Diceros bicornis) was carried out using a primer based on consensus sequence of the minisatellite repeat locus 33.15. Several bands in the range of 3.0 kilobases (kb) to 650 base pairs (bp) were identified that were useful for successful differentiation of R. unicornis from D. bicornis. Of these fragments, a 688 bp one, unique to R. unicornis was cloned and sequenced (Accession No. AF-296689). The band patterns uncovered by MASA and the species-specific hybridisation of pSG5 may be utilised as a tool for differentiating the R. unicornis genome from that of D. bicornis. This approach may also be adopted for the development of DNA-based genetic marker(s) useful for identification of other endangered species

Origin of the Local Group satellite planes

IB was supported by Science and Technology Facilities Council studentship 1506672. The work of DOR was enabled by Royal Astronomical Society undergraduate research bursary 6390/302/001.We attempt to understand the planes of satellite galaxies orbiting the Milky Way (MW) and M31 in the context of Modified Newtonian Dynamics (MOND), which implies a close MW-M31 flyby occurred ≈8 Gyr ago. Using the timing argument, we obtain MW-M31 trajectories consistent with cosmological initial conditions and present observations. We adjust the present M31 proper motion within its uncertainty in order to simulate a range of orbital geometries and closest approach distances. Treating the MW and M31 as point masses, we follow the trajectories of surrounding test particle disks, thereby mapping out the tidal debris distribution. Around each galaxy, the resulting tidal debris tends to cluster around a particular orbital pole. We find some models in which these preferred spin vectors align fairly well with those of the corresponding observed satellite planes. The radial distributions of material in the simulated satellite planes are similar to what we observe. Around the MW, our best-fitting model yields a significant fraction (0.22) of counter-rotating material, perhaps explaining why Sculptor counter-rotates within the MW satellite plane. In contrast, our model yields no counter-rotating material around M31. This is testable with proper motions of M31 satellites. In our best model, the MW disk is thickened by the flyby 7.65 Gyr ago to a root mean square height of 0.75 kpc. This is similar to the observed age and thickness of the Galactic thick disk. Thus, the MW thick disk may have formed together with the MW and M31 satellite planes during a past MW-M31 flyby.PostprintPeer reviewe

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The Olfactory Receptor (OR) superfamily, the largest in the vertebrate genome, is responsible for vertebrate olfaction and is traditionally subdivided into 17 OR families. Recent studies characterising whole-OR subgenomes revealed a 'birth and death' model of evolution for a range of species, however little is known about fine-scale evolutionary dynamics within single-OR families. This study reports the first assessment of fine-scale OR evolution and variation in African mole-rats (Bathyergidae), a family of subterranean rodents endemic to sub-Saharan Africa. Because of the selective pressures of life underground, enhanced olfaction is proposed to be fundamental to the evolutionary success of the Bathyergidae, resulting in a highly diversified OR gene-repertoire. Using a PCR-sequencing approach, we analysed variation in the OR7 family across 14 extant bathyergid species, which revealed enhanced levels of functional polymorphisms concentrated across the receptors' ligand-binding region. We propose that mole-rats are able to recognise a broad range of odorants and that this diversity is reflected throughout their OR7 gene repertoire. Using both classic tests and tree-based methods to test for signals of selection, we investigate evolutionary forces across the mole-rat OR7 gene tree. Four well-supported clades emerged in the OR phylogeny, with varying signals of selection; from neutrality to positive and purifying selection. Bathyergid life-history traits and environmental niche-specialisation are explored as possible drivers of adaptive OR evolution, emerging as non-exclusive contributors to the positive selection observed at OR7 genes. Our results reveal unexpected complexity of evolutionary mechanisms acting within a single OR family, providing insightful perspectives into OR evolutionary dynamics