107 research outputs found
Mejoramiento del saneamiento básico en el centro Poblado Alto Tambillo – Distrito de San Ignacio – Departamento Cajamarca
El estudio de esta investigación se ha generado en 3 partes, un estudio previo de conceptos y teoría, la segunda parte de un proceso de recopilación de datos de manera de trabajo de campo y el tercero punto fue de una manera de interpretación de resultado como un trabajo de gabinete y tomando las decisiones importantes con un previo estudio anteriormente.
Este estudio tiene como principal objetivo el poder mejorar la calidad de servicios básicos ya que en las localidades donde se realizará la investigación no cuentan con un buen sistema privando a la población de satisfacer sus necesidades más elementales.
Si hablamos de manera metodológica, se dice que esta investigación se realizó de manera: aplicada, descriptiva y de diseño no experimental ya que para la recolección de los datos se utilizaron 3 métodos: técnicas de observación directa, análisis documental y ensayos de laboratorio.
Finalizamos realizando el diseño de todas las partes o componentes de ambos sistemas: agua potable y alcantarillado de la localidad en mención, fundamentado en perspectivas técnicas y lógicas junto con estándares aceptables por parte de la ingeniería, garantizando así un funcionamiento óptico, eficaz y eficiente para los pobladores de las zonas.The study of this research has been generated in 3 parts, a previous study of concepts and theory, the second part of a data collection process in the form of field work and the third point was a way of interpreting the result as a cabinet work and making important decisions with a previous study beforehand.
The main objective of this study is to improve the quality of basic services since in the localities where the research will be carried out, they do not have a good system, depriving the population of satisfying their most basic needs.
If we speak methodologically, it is said that this research was carried out in an applied, descriptive and non-experimental design since 3 methods were used for data collection: direct observation techniques, documentary analysis and laboratory tests.
We ended up designing all the parts or components of both systems: drinking water and sewage of the location mentioned, based on technical and logical perspectives together with acceptable standards by engineering, thus guaranteeing an optical, effective and efficient operation. for the inhabitants of the areasTesi
Hydrodynamical Models of Outflow Collimation in YSOs
We explore the physics of time-dependent hydrodynamic collimation of jets
from Young Stellar Objects (YSOs). Using parameters appropriate to YSOs we have
carried out high resolution hydrodynamic simulations modeling the interaction
of a central wind with an environment characterized by a moderate opening angle
toroidal density distribution. The results show that the the wind/environment
interaction produces strongly collimated supersonic jets. The jet is composed
of shocked wind gas. Using analytical models of wind blown bubble evolution we
show that the scenario studied here should be applicable to YSOs and can, in
principle, initiate collimation on the correct scales (R ~ 100 AU). The
simulations reveal a number of time-dependent non-linear features not
anticipated in previous analytical studies including: a prolate wind shock; a
chimney of cold swept-up ambient material dragged into the bubble cavity; a
plug of dense material between the jet and bow shocks. We find that the
collimation of the jet occurs through both de Laval nozzles and focusing of the
wind via the prolate wind shock. Using an analytical model for shock focusing
we demonstrate that a prolate wind shock can, by itself, produce highly
collimated supersonic jets.Comment: Accepted by ApJ, 31 pages with 12 figures (3 JPEG's) now included,
using aasms.sty, Also available in postscript via a gzipped tar file at
ftp://s1.msi.umn.edu/pub/afrank/SFIC1/SFIC.tar.g
The lower mass function of the young open cluster Blanco 1: from 30 Mjup to 3 Mo
We performed a deep wide field optical survey of the young (~100-150 Myr)
open cluster Blanco1 to study its low mass population well down into the brown
dwarf regime and estimate its mass function over the whole cluster mass
range.The survey covers 2.3 square degrees in the I and z-bands down to I ~ z ~
24 with the CFH12K camera. Considering two different cluster ages (100 and 150
Myr), we selected cluster member candidates on the basis of their location in
the (I,I-z) CMD relative to the isochrones, and estimated the contamination by
foreground late-type field dwarfs using statistical arguments, infrared
photometry and low-resolution optical spectroscopy. We find that our survey
should contain about 57% of the cluster members in the 0.03-0.6 Mo mass range,
including 30-40 brown dwarfs. The candidate's radial distribution presents
evidence that mass segregation has already occured in the cluster. We took it
into account to estimate the cluster mass function across the
stellar/substellar boundary. We find that, between 0.03Mo and 0.6Mo, the
cluster mass distribution does not depend much on its exact age, and is well
represented by a single power-law, with an index alpha=0.69 +/- 0.15. Over the
whole mass domain, from 0.03Mo to 3Mo, the mass function is better fitted by a
log-normal function with m0=0.36 +/- 0.07Mo and sigma=0.58 +/- 0.06. Comparison
between the Blanco1 mass function, other young open clusters' MF, and the
galactic disc MF suggests that the IMF, from the substellar domain to the
higher mass part, does not depend much on initial conditions. We discuss the
implications of this result on theories developed to date to explain the origin
of the mass distribution.Comment: 18 pages, 15 figures and 5 tables accepted in A&
The Evolution of Supernovae in Circumstellar Wind Bubbles II: Case of a Wolf-Rayet star
(Abridged) Mass-loss from massive stars leads to the formation of
circumstellar wind-blown bubbles surrounding the star, bordered by a dense
shell. When the star ends its life in a supernova (SN) explosion, the resulting
shock wave will interact with this modified medium. In a previous paper we
discussed the basic parameters of this interaction. In this paper we go a step
further and study the evolution of SNe in the wind blown bubble formed by a 35
\msun star that starts off as an O star, goes through a red supergiant phase,
and ends its life as a Wolf-Rayet star. We model the evolution of the CSM and
then the expansion of the SN shock wave within this medium. Our simulations
clearly reveal fluctuations in density and pressure within the surrounding
medium. The SN shock interacting with these fluctuations, and then with the
dense shell surrounding the wind-blown cavity, gives rise to a variety of
transmitted and reflected shocks in the wind bubble. The interactions between
these various shocks and discontinuities is examined, and its effects on the
X-ray emission is noted. Our simulations reveal the presence of several
hydrodynamic instabilities. They show that the turbulent interior, coupled with
the large fluctuations in density and pressure, gives rise to an extremely
corrugated SN shock wave. The shock shows considerable wrinkles as it impacts
the dense shell, and the impact occurs in a piecemeal fashion, with some parts
of the shock wave interacting with the shell before the others. Therefore
different parts of the shell will `light-up' at different times. The
non-spherical nature of the interaction means that it will occur over a
prolonged period of time, and the spherical symmetry of the initial shock wave
is destroyed.Comment: 50 pages, 19 figures. Accepted to the Astrophysical Journal. For a
version with the original high-resolution color figures please download from
http://astro.uchicago.edu/~vikram/sncsm.htm
Photodissociation in proto-planetary nebulae. Hydrodynamical simulations and solutions for low-velocity multi-lobes
We explore the effects of photodissociation at the stages of post-asymptotic
giant branch stars to find a mechanism able to produce multi-polar shapes. We
perform two-dimensional gasdynamical simulations to model the effects of
photodissociation in proto-planetary nebulae. We find that post-asymptotic
giant branch stars with 7,000 K or hotter are able to photodissociate a large
amount of the circumstellar gas. We compute several solutions for nebulae with
low-velocity multi-lobes. We find that the early expansion of a dissociation
front is crucial to understand the number of lobes in proto-planetary nebulae.
A dynamical instability appears when cooling is included in the swept-up
molecular shell. This instability is similar to the one found in
photoionization fronts, and it is associated with the thin-shell Vishniac
instability. The dissociation front exacerbates the growth of the thin-shell
instability, creating a fast fragmentation in shells expanding into media with
power-law density distributions such as r^-2.Comment: 4 pages, 2 figures, acepted by A&A Letter
Early development of non-hodgkin lymphoma following initiation of newer class antiretroviral therapy among HIV-infected patients - implications for immune reconstitution
<p>Abstract</p> <p>Background</p> <p>In the HAART era, the incidence of HIV-associated non-Hodgkin lymphoma (NHL) is decreasing. We describe cases of NHL among patients with multi-class antiretroviral resistance diagnosed rapidly after initiating newer-class antiretrovirals, and examine the immunologic and virologic factors associated with potential IRIS-mediated NHL.</p> <p>Methods</p> <p>During December 2006 to January 2008, eligible HIV-infected patients from two affiliated clinics accessed Expanded Access Program antiretrovirals of raltegravir, etravirine, and/or maraviroc with optimized background. A NHL case was defined as a pathologically-confirmed tissue diagnosis in a patient without prior NHL developing symptoms after starting newer-class antiretrovirals. Mean change in CD4 and log<sub>10 </sub>VL in NHL cases compared to controls was analyzed at week 12, a time point at which values were collected among all cases.</p> <p>Results</p> <p>Five cases occurred among 78 patients (mean incidence = 64.1/1000 patient-years). All cases received raltegravir and one received etravirine. Median symptom onset from newer-class antiretroviral initiation was 5 weeks. At baseline, the median CD4 and VL for NHL cases (n = 5) versus controls (n = 73) were 44 vs.117 cells/mm3 (p = 0.09) and 5.2 vs. 4.2 log<sub>10 </sub>(p = 0.06), respectively. The mean increase in CD4 at week 12 in NHL cases compared to controls was 13 (n = 5) vs. 74 (n = 50)(p = 0.284). Mean VL log<sub>10 </sub>reduction in NHL cases versus controls at week 12 was 2.79 (n = 5) vs. 1.94 (n = 50)(p = 0.045).</p> <p>Conclusions</p> <p>An unexpectedly high rate of NHL was detected among treatment-experienced patients achieving a high level of virologic response with newer-class antiretrovirals. We observed trends toward lower baseline CD4 and higher baseline VL in NHL cases, with a significantly greater decline in VL among cases by 12 weeks. HIV-related NHL can occur in the setting of immune reconstitution. Potential immunologic, virologic, and newer-class antiretroviral-specific factors associated with rapid development of NHL warrants further investigation.</p
On Luminous Blue Variables as the Progenitors of Core-Collapse Supernovae, especially Type IIn Supernovae
Luminous blue variable (LBV) stars are very massive, luminous, unstable stars
that suffer frequent eruptions. In the last few years, these stars have been
proposed as the direct progenitors of some core-collapse supernovae (SNe),
particularly Type IIn SNe, in conflict with stellar evolution theory. In this
paper we investigate various scenarios wherein LBV stars have been suggested as
the immediate progenitors of SNe. Many of these suggestions stem from the fact
that the SNe appear to be expanding in a high density medium, which has been
interpreted as resulting from a wind with a high mass-loss rate. Others arise
due to perceived similarities between the SN characteristics and those of LBVs.
Only in the case of SN 2005gl do we find a valid possibility for an LBV-like
progenitor. Other scenarios encounter various levels of difficulty. The
evidence that points to LBVs as direct core-collapse SNe progenitors is far
from convincing. High mass-loss rates are often deduced by making assumptions
regarding the wind parameters, which are contradicted by the results
themselves. A high density need not necessarily imply a high wind mass-loss
rate: wind shocks sweeping up the surrounding medium may give a high density
shell with a low associated wind mass-loss rate. High densities may also arise
due to wind clumps, or due to a previous LBV phase before the SN explodes as a
Wolf-Rayet star. Some Type IIn SNe appear to signify more a phase in the life
of a SN than a class of SNe, and may arise from more than one type of
progenitor. A Wolf-Rayet phase that lasts for a few thousand years or less
could be one of the more probable progenitors of Type IIns, and channels for
creating short-lived W-R phases are briefly discussed.Comment: Accepted to MNRAS. 13 pages, 1 figur
The ACS Fornax Cluster Survey. IX. The Color-Magnitude Relation of Globular Cluster Systems
We investigate the color-magnitude relation for globular clusters (GCs) --
the so-called "blue tilt" -- detected in the ACS Fornax Cluster Survey and
using the combined sample of GCs from the ACS Fornax and Virgo Cluster Surveys.
We find a tilt of gamma_z=d(g-z)/dz=-0.0257 +- 0.0050 for the full GC sample of
the Fornax Cluster Survey (~5800 GCs). This is slightly shallower than the
value gamma_z=-0.0459 +- 0.0048 found for the Virgo Cluster Survey GC sample
(~11100 GCs). The slope for the merged Fornax and Virgo datasets (~16900 GCs)
is gamma_z=-0.0293 +- 0.0085, corresponding to a mass-metallicity relation of Z
~ M^0.43. We find that the blue tilt sets in at GC masses in excess of M ~
2*10^5 M_sun. The tilt is stronger for GCs belonging to high-mass galaxies (M_*
> 5 * 10^10 M_sun) than for those in low-mass galaxies (M_* < 5 * 10^10 M_sun).
It is also more pronounced for GCs with smaller galactocentric distances. Our
findings suggest a range of mass-metallicity relations Z_GC ~ M_GC^(0.3-0.7)
which vary as a function of host galaxy mass/luminosity. We compare our
observations to a recent model of star cluster self-enrichment with generally
favorable results. We suggest that, within the context of this model, the
proto-cluster clouds out of which the GCs formed may have had density profiles
slightly steeper than isothermal and/or star formation efficiencies somewhat
below 0.3. We caution, however, that the significantly different appearance of
the CMDs defined by the GC systems associated with galaxies of similar mass and
morphological type pose a challenge to any single mechanism that seeks to
explain the blue tilt. We therefore suggest that the merger/accretion histories
of individual galaxies have played a non-negligible role determining the
distribution of GCs in the CMDs of individual GC systems
Laboratory Astrophysics and Collimated Stellar Outflows: The Production of Radiatively Cooled Hypersonic Plasma Jets
We present first results of astrophysically relevant experiments where highly
supersonic plasma jets are generated via conically convergent flows. The
convergent flows are created by electrodynamic acceleration of plasma in a
conical array of fine metallic wires (a modification of the wire array
Z-pinch). Stagnation of plasma flow on the axis of symmetry forms a standing
conical shock effectively collimating the flow in the axial direction. This
scenario is essentially similar to that discussed by Canto\' ~and collaborators
as a purely hydrodynamic mechanism for jet formation in astrophysical systems.
Experiments using different materials (Al, Fe and W) show that a highly
supersonic (), well-collimated jet is generated when the radiative
cooling rate of the plasma is significant. We discuss scaling issues for the
experiments and their potential use for numerical code verification. The
experiments also may allow direct exploration of astrophysically relevant
issues such as collimation, stability and jet-cloud interactions.Comment: 13 Pages, (inc 4 figs), LaTex, Submitted to ApJ Let
Discovery of a compact gas-rich DLA galaxy at z = 2.2: evidences for a starburst-driven outflow
We present the detection of Ly-alpha, [OIII] and H-alpha emission associated
with an extremely strong DLA system (N(HI) = 10^22.10 cm^-2) at z=2.207 towards
the quasar SDSS J113520-001053. This is the largest HI column density ever
measured along a QSO line of sight, though typical of what is seen in GRB-DLAs.
This absorption system also classifies as ultrastrong MgII system with
W2796_r=3.6 A. The mean metallicity of the gas ([Zn/H]=-1.1) and dust depletion
factors ([Zn/Fe]=0.72, [Zn/Cr]=0.49) are consistent with (and only marginally
larger than) the mean values found in the general QSO-DLA population. The
[OIII]-Ha emitting region has a very small impact parameter with respect to the
QSO line of sight, b=0.1", and is unresolved. From the Ha line, we measure
SFR=25 Msun/yr. The Ly-a line is double-peaked and is spatially extended. More
strikingly, the blue and red Ly-a peaks arise from distinct regions extended
over a few kpc on either side of the star-forming region. We propose that this
is the consequence of Ly-a transfer in outflowing gas. The presence of
starburst-driven outflows is also in agreement with the large SFR together with
a small size and low mass of the galaxy (Mvir~10^10 Msun). From the stellar UV
continuum luminosity of the galaxy, we estimate an age of at most a few 10^7
yr, again consistent with a recent starburst scenario. We interpret the data as
the observation of a young, gas rich, compact starburst galaxy, from which
material is expelled through collimated winds powered by the vigorous star
formation activity. We substantiate this picture by modelling the radiative
transfer of Ly-a photons in the galactic counterpart. Though our model (a
spherical galaxy with bipolar outflowing jets) is a simplistic representation
of the true gas distribution and velocity field, the agreement between the
observed and simulated properties is particularly good. [abridged]Comment: 15 pages, 18 figures, 4 tables, accepted for publication in Astronomy
and Astrophysic
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