3,112 research outputs found
Caracterización hidrológica de los embalses destinados para generación de energía en la región Antioquia
Trabajo de InvestigaciónTrata sobre el estudio hidrológico que afecta las cuencas de los embalses ubicados en la región de Antioquia y teniendo en cuenta que estos son la principal fuente de suministro de agua para unos usos determinados, por éste motivo se debe caracterizar, monitorear y estudiar los comportamientos del líquido, toda vez que se puede presentar con mayor o menor intensidad en algunos periodos del año, afectando de forma considerada a los usuarios que se benefician de éstos. Gracias a los registros hidrológicos y el apoyo de programas relacionados con el área, podemos determinar las condiciones hidrometeorológicas lo cual permitirá evaluar las variables de caudal, nivel y precipitación en periodos de lluvia o estiaje, con esto se puede incidir en el comportamiento de los embalses lo cual repercutirá directamente sobre las fuentes hídricas aguas abajo.1. INTRODUCCIÓN
2. ANTECEDENTES
3. PLANEAMIENTO DEL PROBLEMA
4. OBJETIVOS
5. JUSTIFICACION
6. DELIMITACION
7. MARCO REFERENCIAL
8. METODOLOGÍA 9. DISEÑO METODOLÓGICO
10. CRONOGRAMA
11. PRODUCTOS A ENTREGAR
12. INSTALACIONES Y EQUIPO REQUERIDO
13. PRESUPUESTO
14. ESTRATEJIAS DE COMNICACION Y DIVULGACION
15. ANALISIS DE RESULTADOS
16. COBCLUSIONES
17. RECOMENDACIONESPregradoIngeniero Civi
Probing the Masses of the PSR J0621+1002 Binary System Through Relativistic Apsidal Motion
Orbital, spin and astrometric parameters of the millisecond pulsar PSR
J0621+1002 have been determined through six years of timing observations at
three radio telescopes. The chief result is a measurement of the rate of
periastron advance, omega_dot = 0.0116 +/- 0.0008 deg/yr. Interpreted as a
general relativistic effect, this implies the sum of the pulsar mass, m_1, and
the companion mass, m_2, to be M = m_1 + m_2 = 2.81 +/- 0.30 msun. The
Keplerian parameters rule out certain combinations of m_1 and m_2, as does the
non-detection of Shapiro delay in the pulse arrival times. These constraints,
together with the assumption that the companion is a white dwarf, lead to the
68% confidence maximum likelihood values of m_1 = 1.70(+0.32 -0.29) msun and
m_2 =0.97(+0.27 - 0.15) msun and to the 95% confidence maximum likelihood
values of m_1 = 1.70(+0.59 -0.63) msun and m_2 = 0.97(+0.43 -0.24) msun. The
other major finding is that the pulsar experiences dramatic variability in its
dispersion measure (DM), with gradients as steep as 0.013 pc cm^{-3} / yr. A
structure function analysis of the DM variations uncovers spatial fluctuations
in the interstellar electron density that cannot be fit to a single power law,
unlike the Kolmogorov turbulent spectrum that has been seen in the direction of
other pulsars. Other results from the timing analysis include the first
measurements of the pulsar's proper motion, mu = 3.5 +/- 0.3 mas / yr, and of
its spin-down rate, dP/dt = 4.7 x 10^{-20}, which, when corrected for kinematic
biases and combined with the pulse period, P = 28.8 ms, gives a characteristic
age of 1.1 x 10^{10} yr and a surface magnetic field strength of 1.2 x 10^{9}
G.Comment: Accepted by ApJ, 10 pages, 5 figure
Effect of Terminal Groups of Dendrimers in the Complexation with Antisense Oligonucleotides and Cell Uptake
Indexación: Web of Science.Poly(amidoamine) dendrimers are the most recognized class of dendrimer. Amino-terminated (PAMAM-NH2) and hydroxyl-terminated (PAMAM-OH) dendrimers of generation 4 are widely used, since they are commercially available. Both have different properties, mainly based on their different overall charges at physiological pH. Currently, an important function of dendrimers as carriers of short single-stranded DNA has been applied. These molecules, known as antisense oligonucleotides (asODNs), are able to inhibit the expression of a target mRNA. Whereas PAMAM-NH2 dendrimers have shown to be able to transfect plasmid DNA, PAMAM-OH dendrimers have not shown the same successful results. However, little is known about their interaction with shorter and more flexible molecules such as asODNs. Due to several initiatives, the use of these neutral dendrimers as a scaffold to introduce other functional groups has been proposed. Because of its low cytotoxicity, it is relevant to understand the molecular phenomena involving these types of dendrimers. In this work, we studied the behavior of an antisense oligonucleotide in presence of both types of dendrimers using molecular dynamics simulations, in order to elucidate if they are able to form stable complexes. In this manner, we demonstrated at atomic level that PAMAM-NH2, unlike PAMAM-OH, could form a well-compacted complex with asODN, albeit PAMAM-OH can also establish stable interactions with the oligonucleotide. The biological activity of asODN in complex with PAMAM-NH2 dendrimer was also shown. Finally, we revealed that in contact with PAMAM-OH, asODN remains outside the cells as TIRF microscopy results showed, due to its poor interaction with this dendrimer and cell membranes.http://nanoscalereslett.springeropen.com/articles/10.1186/s11671-016-1260-
Chandra Observations of Black-Widow Pulsars
We describe the first X-ray observations of binary millisecond pulsars PSRs
J0023+0923, J1810+1744, J2215+5135, and J2256-1024. All four are Fermi
gamma-ray sources and three are 'black-widow' pulsars, with companions of mass
< 0.1 solar masses. Data were taken using the Chandra X-Ray Observatory and
covered a full binary orbit for each pulsar. Two pulsars, PSRs J2215+5135 and
J2256-1024, show significant orbital variability and X-ray flux minima at the
times of eclipses observed at radio wavelengths. This phenomenon is consistent
with intrabinary shock emission characteristic of black-widow pulsars. The
other two pulsars, PSRs J0023+0923 and J1810+1744, do not demonstrate
significant variability, but are fainter than the other two sources. Spectral
fits yield power-law indices that range from 1.4 to 2.3 and blackbody
temperatures in the hundreds of eV. The spectrum for PSR J2215+5135 shows a
significant hard X-ray component (41% of counts are above 2 keV), which is
additional evidence for the presence of intrabinary shock emission.Comment: 3 pages, 2 figures, 1 table, 2012 IAU General Assembl
Twenty-One Millisecond Pulsars in Terzan 5 Using the Green Bank Telescope
We have discovered 21 millisecond pulsars (MSPs) in the globular cluster
Terzan 5 using the Green Bank Telescope, bringing the total of known MSPs in
Terzan 5 to 24. These discoveries confirm fundamental predictions of globular
cluster and binary system evolution. Thirteen of the new MSPs are in binaries,
of which two show eclipses and two have highly eccentric orbits. The
relativistic periastron advance for the two eccentric systems indicates that at
least one of these pulsars has a mass >1.68 Msun at 95% confidence. Such large
neutron star masses constrain the equation of state of matter at or beyond the
nuclear equilibrium density.Comment: 12 pages, 2 figures. Accepted by Science. Published electronically
via Science Express 13 Jan 200
Eight new MSPs in NGC 6440 and NGC 6441
We report the discovery of five new millisecond pulsars in the globular
cluster NGC 6440 and three new ones in NGC 6441; each cluster has one
previously known pulsar. Four of the new pulsars are found in binary systems.
One of the new pulsars, PSR J1748-2021B in NGC 6440, is notable for its
eccentric (e = 0.57) and wide (P_b = 20.5 days) orbit. If the rate of advance
of periastron is due solely to general relativity, we can estimate of the total
mass of this binary system: 2.92 +/- 0.20 solar masses. This would imply an
anomalously large mass for this pulsar, which could introduce important
constraints in the study of the equation of state for cold neutron matter.Comment: 3 pages, 3 figures. To appear in the proceedings of "40 Years of
Pulsars: Millisecond Pulsars, Magnetars, and More", August 12-17, 2007,
McGill University, Montreal, Canad
Prevalence of mutans streptococci isolated from complete dentures and their susceptibility to mouthrinses
The aims of this study were to evaluate the incidence of mutans streptococci (MS - sessile form) on complete maxillary dentures after use of a specific denture paste, and to determine the minimum inhibitory concentration (MIC) and maximum inhibitory dilution (MID) of 3 oral mouthrinses: Cepacol, Plax and Periogard. Seventy-seven complete denture wearers were randomly assigned into 2 groups, according to the product used for denture cleaning: Control group - conventional dentifrice (Kolynos-Super White); and Test group: experimental denture cleaning paste. Denture biofilm was collected at baseline and after 90 and 180 days after treatment by brushing the dentures with saline solution. After decimal serial dilution, samples were seeded onto agar sucrose bacitracin to count colonies with morphological characteristics of MS. MS identification was performed by the sugar fermentation tests. After this procedure, brain heart infusion broth (BHI) was added to oral mouthrinses (Plax, Cepacol e Periogard) and seeded on Petri dishes. The colonies were seeded using the Steers multiplier and, after the incubation, the MIC and MID of the mouthrinses were calculated. The results showed an incidence of 74.0% (n=57) of MS in the 77 complete dentures examined in the study, being 76.3% (n=29) of the Control group (conventional dentifrice) and 71.8% (28) of the Test group (experimental denture cleaning paste). In both groups, the number of positive cases for MS decreased from day 0 to day 180. In the Test group there was a slight decrease in the incidence of Streptococcus mutans 90 days after use of the experimental denture cleaning paste, which was not observed in the Control group. As regards to mouthrinses, for both groups, Periogard showed antimicrobial action with the highest dilution, followed by Cepacol and Plax. In conclusion, the incidence of MS in complete dentures was high and Periogard was the mouthrinse with the strongest antimicrobial action against MS. The experimental denture cleaning paste showed a slight action against S. mutans after 90 days of treatment.O objetivo deste estudo foi avaliar a incidência de estreptococos do grupo mutans (forma séssil) de próteses totais superiores após o uso de uma pasta específica para higienização de próteses totais, bem como determinar a concentração inibitória mínima (CIM) e diluição inibitória máxima (DIM) de 3 enxaguatórios bucais: Cepacol, Plax e Periogard. Setenta e sete usuários de próteses totais foram distribuídos em 2 grupos: (A) grupo Controle: dentifrício convencional (Kolynos Super Branco) e (B) grupo Teste: pasta experimental para higiene de próteses (1). O biofilme das próteses foi coletado no início e após 90 e 180 dias dos tratamentos, por meio de escovação das próteses com solução salina. Após a diluição decimal seriada, as amostras foram semeadas em agar sacarose bacitracina para a contagem de colônias características de estreptococos do grupo mutans. A identificação dos estreptococos do grupo mutans foi realizada por meio de testes de fermentação de açúcares. Após este procedimento, o caldo de infusão de cérebro e coração (BHI) foi adicionado aos antissépticos (Plax, Cepacol e Periogard) e semeado em placas de Petri. As colônias foram semeadas usando o mutiplicador de Steers e após a incubação, a concentração inibitória mínima e a concentração inibitória máxima dos enxaguatórios foram calculadas. Os resultados mostraram que a incidência de estreptococos do grupo mutans nas 77 próteses totais examinadas foi de 74,0% (n=57), sendo 76,3% (n=29) do grupo Controle (pasta convencional) e 71,8% (n=28) do grupo Teste (pasta experimental). Em ambos os grupos, o número de casos positivos para estreptococos do grupo mutans diminuiu, do início (0 dias) para 180 dias. Houve uma pequena diminuição da incidência de Streptococcus mutans após 90 dias do uso da pasta experimental, o que não foi observado no grupo controle. Com relação aos enxaguatórios, para ambos os grupos, o Periogard apresentou atividade antimicrobiana com diluições maiores, seguido do Cepacol e Plax. Pôde-se concluir que a incidência de estreptococos do grupo mutans em próteses totais foi elevada e que o Periogard foi o enxaguatório com melhor ação antimicrobiana contra os estreptococos do grupo mutans. A pasta experimental mostrou uma pequena ação contra S. mutans após 90 dias de tratamento
Chandra Smells a RRAT: X-ray Detection of a Rotating Radio Transient
"Rotating RAdio Transients" (RRATs) are a newly discovered astronomical
phenomenon, characterised by occasional brief radio bursts, with average
intervals between bursts ranging from minutes to hours. The burst spacings
allow identification of periodicities, which fall in the range 0.4 to 7
seconds. The RRATs thus seem to be rotating neutron stars, albeit with
properties very different from the rest of the population. We here present the
serendipitous detection with the Chandra X-ray Observatory of a bright
point-like X-ray source coincident with one of the RRATs. We discuss the
temporal and spectral properties of this X-ray emission, consider counterparts
in other wavebands, and interpret these results in the context of possible
explanations for the RRAT population.Comment: 5 pages, 2 b/w figures, 1 color figure. To appear in the proceedings
of "Isolated Neutron Stars", Astrophysics & Space Science, in pres
Sudden spleen rupture in a Plasmodium vivax-infected patient undergoing malaria treatment
BACKGROUND: Splenomegaly is one of the most common features of
malaria. However, spontaneous splenic rupture, although unusual,
represents a severe complication often leading to death. It is
mostly seen in acute infection and primary attack, and it is
most commonly associated with Plasmodium vivax. Here, a case of
spontaneous splenic rupture diagnosed with a portable ultrasound
apparatus shortly after starting treatment and with recurrent
parasitaemia after splenectomy, is reported. CASE DESCRIPTION:
In November 2015, a 45-year-old Brazilian man presented to the
hospital in Manaus with fever, headache and myalgia. He was
diagnosed with P. vivax malaria and, after a normal G6PD test,
he started treatment with chloroquine and primaquine and was
discharged. Two days later, he went back to the hospital with
abdominal pain, dyspnea, dry cough, pallor, oliguria and fever.
Using a portable ultrasound, he was diagnosed of rupture of the
spleen, which was removed by emergency surgery. After this
episode, he suffered two more malaria episodes with high
parasitaemia at approximately 2-month intervals. DNA from
different portions of the spleen was extracted and a qualitative
PCR was performed to detect P. vivax. CONCLUSIONS: The splenic
rupture suffered by this patient occurred 2 days after starting
the treatment. Having a portable ultrasound apparatus may have
saved the patient's life, as it revealed a haemorrhage needing
an urgent surgery. Parasites were detected by PCR in the
extracted spleen. This patient suffered two more vivax malaria
diagnosed episodes in spite of receiving and completing
treatment with chloroquine and primaquine for each clinical
attack. Splenic rupture during acute malaria is uncommon, but it
is likely underdiagnosed and underreported, because the lack of
means and equipment hinders diagnostic confirmation, especially
in endemic areas
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