2,699 research outputs found
Magnetic Field Effects on the Head Structure of Protostellar Jets
We present the results of 3-D SPMHD numerical simulations of
supermagnetosonic, overdense, radiatively cooling jets. Two initial magnetic
configurations are considered: (i) a helical and (ii) a longitudinal field. We
find that magnetic fields have important effects on the dynamics and structure
of radiative cooling jets, especially at the head. The presence of a helical
field suppresses the formation of the clumpy structure which is found to
develop at the head of purely hydrodynamical jets. On the other hand, a cooling
jet embedded in a longitudinal magnetic field retains clumpy morphology at its
head. This fragmented structure resembles the knotty pattern commonly observed
in HH objects behind the bow shocks of HH jets. This suggests that a strong
(equipartition) helical magnetic field configuration is ruled out at the jet
head. Therefore, if strong magnetic fields are present, they are probably
predominantly longitudinal in those regions. In both magnetic configurations,
we find that the confining pressure of the cocoon is able to excite
short-wavelength MHD K-H pinch modes that drive low-amplitude internal shocks
along the beam. These shocks are not strong however, and it likely that they
could only play a secondary role in the formation of the bright knots observed
in HH jets.Comment: 14 pages, 2 Gif figures, uses aasms4.sty. Also available on the web
page http://www.iagusp.usp.br/preprints/preprint.html. To appear in The
Astrophysical Journal Letter
On the existence of 0/1 polytopes with high semidefinite extension complexity
In Rothvo\ss{} it was shown that there exists a 0/1 polytope (a polytope
whose vertices are in \{0,1\}^{n}) such that any higher-dimensional polytope
projecting to it must have 2^{\Omega(n)} facets, i.e., its linear extension
complexity is exponential. The question whether there exists a 0/1 polytope
with high PSD extension complexity was left open. We answer this question in
the affirmative by showing that there is a 0/1 polytope such that any
spectrahedron projecting to it must be the intersection of a semidefinite cone
of dimension~2^{\Omega(n)} and an affine space. Our proof relies on a new
technique to rescale semidefinite factorizations
Systemic Treatment of Metastatic Conjunctival Melanoma.
Conjunctival melanoma (CM) is an exceptionally rare tumor, with a propensity for local and distant recurrence, with the lungs, skin, liver, and brain being the most common sites of metastasis. Recent progress in systemic treatments, with checkpoint inhibitors and targeted therapies blocking BRAF and MEK, has redefined the standard of care of advanced unresectable and metastatic melanoma. Although most trials did not include patients with conjunctival melanoma, its close molecular and genetic relationship to cutaneous melanoma might suggest a similar response to these novel agents. The authors describe two uncommon cases of metastatic conjunctival melanomas with distinct genetic profiles and, as such, submitted to different systemic treatments.info:eu-repo/semantics/publishedVersio
Mathematical retroreflectors
Retroreflectors are optical devices that reverse the direction of incident
beams of light. Here we present a collection of billiard type retroreflectors
consisting of four objects; three of them are asymptotically perfect
retroreflectors, and the fourth one is a retroreflector which is very close to
perfect. Three objects of the collection have recently been discovered and
published or submitted for publication. The fourth object - notched angle - is
a new one; a proof of its retroreflectivity is given.Comment: 32 pages, 19 figure
Efeito da toxicidade de Cr (VI) e Zn (II) no crescimento do fungo filamentoso Aspergillus niger isolado de efluente industrial.
Processos convencionais de tratamento de efluentes utilizam microrganismos vivos, o que sugere limitações relativas à toxicidade de metais para os microrganismos. O experimento consistiu em adicionar soluções monoelementares de Cr (VI) e Zn(II) em diferentes concentrações (0, 20, 50, 100, 200, 300, 400, 500 mg.L-1) ao meio de crescimento e observar a influência dos metais no crescimento micelial e germinativo do fungo Aspergillus Níger por verificação visual da expansão radial do micélio e da germinação de esporos, seguida de registro fotográfico. Os resultados mostraram que o metabolismo do fungo foi completamente inibido em concentrações acima de 500 mg Zn (II).L-1 e 150 mg Cr (VI).L-1. O ED50 (concentração de ingrediente ativo capaz de inibir 50% do crescimento micelial do fungo) para os dois íons metálicos, nas condições estudadas, está na faixa entre 100 e 150 mg.L-1
Systemic Treatment of Metastatic Conjunctival Melanoma
Conjunctival melanoma (CM) is an exceptionally rare tumor, with a propensity for local and distant recurrence, with the lungs, skin, liver, and brain being the most common sites of metastasis. Recent progress in systemic treatments, with checkpoint inhibitors and targeted therapies blocking BRAF and MEK, has redefined the standard of care of advanced unresectable and metastatic melanoma. Although most trials did not include patients with conjunctival melanoma, its close molecular and genetic relationship to cutaneous melanoma might suggest a similar response to these novel agents. The authors describe two uncommon cases of metastatic conjunctival melanomas with distinct genetic profiles and, as such, submitted to different systemic treatments.info:eu-repo/semantics/publishedVersio
An Eleven-Year-Old Boy With Arthritis of the Hip Joint, and an 8-Year-Old Boy With Sacroiliitis
info:eu-repo/semantics/publishedVersio
Chemical composition and bioactivity of essential oils and extracts from Oregano from Madeira Island, Portugal
In the course of ongoing investigations on polymorphic Lamiaceae species, we
studied Origanum vulgare spp. virens growing wild in several locations of Madeira
Island, Portugal. Variation in essential oil composition with climate conditions was
studied. The antimicrobial activity of the various essential oils was determined
against 10 strains of bacteria and yeasts, usually found as human pathogenic or food
contaminants. The essential oils inhibited all the bacteria tested excepting for P.
aeruginosa. The most sensitive microorganism was M. smegmatis with MIC = 25 µg
ml-1 for two of the oils. The results of this study suggest a potential application of
these oils in preventing the human pathogenic and food contaminant
microorganisms growth. Radical scavenging capacity of essential oils and solvent
extract (hexane, chloroform, ethyl acetate and methanol) were also determined,
since interest of oregano resides in both non polar and polar fractions, all known by
their very high antioxidant activity. From the hexane fraction, we obtained a large
amount of 1-hexacosanol, C26H54O, a long chain alcohol, which was previously
extracted in the non-esterified form only from Hygrophila erecta.info:eu-repo/semantics/publishedVersio
Valores como predictores de satisfacción con la vida en los jóvenes
Numa perspectiva funcionalista, os valores são uma expressão cognitiva das necessidades humanas, princípios que orientam o comportamento para metas mais pessoais, sociais ou gerais de vida, cujo impacto psicossocial merece mais investigação. Neste estudo, analisou-se em que medida o tipo de orientação dos valores prediz a satisfação com a vida de 562 jovens portugueses (n = 303, 53,9% mulheres), com idades entre 14 e 22 anos (M = 16,9, DP = 1,71), que frequentam o ensino médio: via profissionalizante (63,7%) e regular (36,3%). Os jovens completaram o Questionário de Valores Básicos e a Escala de Satisfação com a Vida. Os resultados da análise de regressão linear indicam que a orientação dos valores explica menos de um quarto da variabilidade da satisfação com a vida, o que suscita a necessidade de se analisar o seu poder explicativo em conjunto com outras variáveis, por exemplo, de personalidade e sociocognitivas.In a functionalist perspective, values are a cognitive expression of human needs as well as principles that guide behaviors to personal, social or general life goals, whose psychosocial impact deserves more investigation. This study aimed to analyze whether the type of values orientation predicts life satisfaction in 562 Portuguese youths (n = 303, 53.9% women) aged 14 to 22 years (M = 16.9; SD = 1.71), attending high school studies, being 63.7% technical and (36.3%) regular high school.Students completed the Basic Values Survey and the Satisfaction With Life Scale. The results of the linear regression analyzes indicate that the values orientation explains less than a quarter of life satisfaction variability, which indicated the need to further analyze its explanatory power together with other variables, such as, personality and socio-cognitive.Desde el punto de vista funcional, los valores son una expresión cognitiva de las necesidades humanas, principios que orientan el comportamiento hacia metas más personales, sociales o generales de vida, cuyo impacto psicosocial necesita más investigación. En este estudio se analizó en qué medida el tipo de orientación de los valores predice la satisfacción con la vida de 562 jóvenes portugueses (n = 303, 53.9% mujeres), con edades entre 14 y 22 años ( = 16.9, P = 1.71) que frecuentan Enseñanza Secundaria: profesional (63.7%) y normal (36.3%). Los jóvenes completaron el Cuestionario de Valores Básicos y la Escala de Satisfacción con la Vida. Los resultados del análisis de regresión lineal indican que la orientación de los valores explica menos de una cuarta parte de la variabilidad de satisfacción con la vida, lo que plantea la necesidad de analizar su poder explicativo, junto con otras variables, por ejemplo, de personalidad y socio-cognitivas.(undefined)info:eu-repo/semantics/publishedVersio
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