Monomial transformations of the projective space

We prove that, over any field, the dimension of the indeterminacy locus of a rational transformation $f$ of $P^n$ which is defined by monomials of the same degree $d$ with no common factors is at least $(n-2)/2$, provided that the degree of $f$ as a map is not divisible by $d$. This implies upper bounds on the multidegree of $f$

Magnetic monopole and string excitations in a two-dimensional spin ice

We study the magnetic excitations of a square lattice spin-ice recently produced in an artificial form, as an array of nanoscale magnets. Our analysis, based upon the dipolar interaction between the nanomagnetic islands, correctly reproduces the ground-state observed experimentally. In addition, we find magnetic monopole-like excitations effectively interacting by means of the usual Coulombic plus a linear confining potential, the latter being related to a string-like excitation binding the monopoles pairs, what indicates that the fractionalization of magnetic dipoles may not be so easy in two dimensions. These findings contrast this material with the three-dimensional analogue, where such monopoles experience only the Coulombic interaction. We discuss, however, two entropic effects that affect the monopole interactions: firstly, the string configurational entropy may loose the string tension and then, free magnetic monopoles should also be found in lower dimensional spin ices; secondly, in contrast to the string configurational entropy, an entropically driven Coulomb force, which increases with temperature, has the opposite effect of confining the magnetic defects.Comment: 8 pages. Accepted by Journal of Applied Physics (2009

Efeito da radiação ultravioleta-B sobre a germinação de conídios de Botrytis cinerea e colonização em discos de morango.

RESUMO: O ultravioleta é um fator de grande impacto na agricultura e está intimamente relacionado à camada de ozônio, a qual vem sendo reduzida paulatinamente, em consequência das atividades antrópicas. A camada de ozônio está sendo degradada, principalmente, por ação dos clorofluorcarbonos (CFC) utilizados pelo homem alterando assim a intensidade de radiação ultravioleta na superfície terrestre em especial no comprimento de onda da radiação ultravioleta B (UV-B). O objetivo do trabalho foi avaliar a resistência de conídios de Botrytis cinerea à radiação UV-B. Foram testados 13 isolados do patógeno, onde uma suspensão contendo 105 conídios mL-1 de cada isolado foi preparada e uma alíquota de 20 ?L foi colocada no centro de uma placa de Petri contendo BDA. Os conídios foram expostos à radiação UV-B 5,6 kJ m-2 a uma irradiância de 823 mW m-2. Também foi avaliada a esporulação de B. cinerea em discos de folha de morangueiro em meio de cultura paraquat-clorofenicolágar (PCA). Os isolados apresentaram germinação relativa entre 15% e 90%, sendo que os isolados com maior resistência à radiação UV-B foram o LQC 162, LQC 150 e LQC 159. No teste da esporulação foi observado maior diferenças entre os isolados quanto a formação de conidióforos do patógeno sendo os isolados LQC 150 e LQC 157 superiores aos outros isolados. Foi selecionado o isolado LQC 150 para ensaios posteriores onde será comparada a tolerância desse isolado com isolados de agentes de controle biológico deste patógeno quanto a tolerância a radiação UV-B

Efeito da radiação UV-B sobre a capacidade antagônica de Clonostachys rosea a Botrytis cinerea em discos de folha de morango.

Resumo:: As atividades antrópicas estão alterando a concentração de gases na atmosfera, o ozônio da troposfera é um dos afetados e consequentemente a incidência de raios ultravioleta B (UV-B) na superfície da Terra tem sido alterada. A sensibilidade à radiação UV-B é uma das limitações do uso de agentes de biocontrole a campo. O objetivo deste trabalho foi avaliar o efeito da radiação UV-B em um isolado de Clonostachys rosea e quantificar a capacidade antagônica a Botrytis cinerea em discos de folhas de morango. Foram utilizadas quatro concentrações de conídios de C. rosea e quatro diferentes doses de radiação UV-B, sendo metade dos discos irradiados desafiados com conídios de B. cinerea. As concentrações de conídios de C. rosea acima de 105 conídios mL-1 apresentaram maior tolerância a radiação UV-B e apresentou nível de controle do patógeno superior a 75%, mesmo com a exposição à radiação. De acordo com os resultados, além de mostrar menor crescimento sob radiação UV-B, conídios de C. rosea apresentaram menor capacidade antagônica ao patógeno. Estudos adicionais são necessários para observar a tolerância de isolados de B. cinerea à radiação UV-B e assim, sugerir que um ambiente com radiação UV-B aumentada possa favorecer o patógeno

The Portuguese Severe Asthma Registry: Development, Features, and Data Sharing Policies

The Portuguese Severe Asthma Registry (Registo de Asma Grave Portugal, RAG) was developed by an open collaborative network of asthma specialists. RAG collects data from adults and pediatric severe asthma patients that despite treatment optimization and adequate management of comorbidities require step 4/5 treatment according to GINA recommendations. In this paper, we describe the development and implementation of RAG, its features, and data sharing policies. The contents and structure of RAG were defined in a multistep consensus process. A pilot version was pretested and iteratively improved. The selection of data elements for RAG considered other severe asthma registries, aiming at characterizing the patient's clinical status whilst avoiding overloading the standard workflow of the clinical appointment. Features of RAG include automatic assessment of eligibility, easy data input, and exportable data in natural language that can be pasted directly in patients' electronic health record and security features to enable data sharing (among researchers and with other international databases) without compromising patients' confidentiality. RAG is a national web-based disease registry of severe asthma patients, available at asmagrave.pt. It allows prospective clinical data collection, promotes standardized care and collaborative clinical research, and may contribute to inform evidence-based healthcare policies for severe asthma.info:eu-repo/semantics/publishedVersio

Voluntary Risk Taking By Young Bicyclists:A Case Study of University Students at Montreal

Young bicyclists in Montreal are taking voluntary risks such as bicycling without wearing helmet and braking system of bicycle although they are aware of the presence of danger. This article analyses the behaviour of young bicyclists taking voluntary risks. The university students in Montreal are considered as the case study since they are more risk takers and the bicycle is a favorite mode of transport among them. This study reveals that half of the respondents did not use helmets. They were also spontaneously taking a risk by high speeding, violating signals, bicycling in mixed traffic, ignoring protective equipment after dark, and avoiding the bicycle designated roads. They were taking voluntary risks based on their attitude, subjective norm and perceived behavioural control. They did not perceive the severity of risks since they experienced relevant and unremarkable minor injuries. The attractiveness of risk and accomplishing the risk activities encouraged the young bicyclists to take voluntary risks repeatedly. Increasing feelings of vulnerability among young bicyclists reduce voluntary risks taking attitude and physical and psychological sufferings of the victims of bicycle-related accidents. Findings of this study suggest that the City of Montreal as well as other cities consider the behaviour of bicyclists particularly the young people to avoid bicycle-related accidents along with other physical measures