1,990 research outputs found
Distribución del goce en la trama familiar
En el presente trabajo la Dra. Hartmann desarrolla conceptualizaciones acerca de la familia desde la perspectiva del psicoanálisis lacaniano, planteando a la familia en relación a la distribución de los goces y al malentendido de los sexos, en función directa a la imposibilidad de escritura de la proporción sexual. Tras el cuadro familiar se observan las líneas del goce, las de las pasiones del ser (amor, odio, ignorancia), la satisfacción pulsional, en una economía de ganancias y pérdidas, que puede ubicarse tanto desde el lustgewinn freudiano como desde la noción de plus de gozar lacaniana. Otra de las nociones presentadas por la autora es la de trama, la cual se plantea en tanto el desafío clínico del trabajo con familias donde la "tela" para el trabajo con el inconsciente es escasa.Así quedan planteadas las consecuencias para un niño de tener o no tener lugar en el Deseo Materno y la operatoria del Nombre del Padre, con sus avatares cuando el padre ocupa un lugar poderoso o un lugar humillado. El texto plantea asimismo, las distintas ubicaciones del niño, y sus distintas consecuencias clínicas, de acuerdo a los desarrollos del escrito "Dos notas sobre el Niño" De Jacques Lacan. El niño portando un síntoma en sintonía con el síntoma familiar, el niño ubicado en correlación al fantasma materno y como puro objeto de la madre
Curva de crecimiento de α Bootis, k2 pec
Uno de los métodos más eficaces para el estudio de las atmósferas estelares, es sin duda, el de la curva de crecimiento. Esta curva vincula la intensidad de la línea con el número de átomos activos Nₐ que hay en una columna del 1 cm² de sección, de la fotosfera.
Para α Bootis, ya Suzanne E. A. van Dijke, obtuvo una curva de crecimiento con líneas del Fe I. En la presente investigación se ensaya construir la curva de crecimiento de esta estrella, tipo espectral K₂, III pec. según el “Atlas” de Morgan, Keenan y Kellmann, para otros elementos.Material digitalizado en SEDICI gracias a la Biblioteca de la Facultad de Ciencias Astronómicas y Geofísicas.Observatorio Astronómico de La Plat
A Search for Star-Disk Interaction Among the Strongest X-ray Flaring Stars in the Orion Nebula Cluster
The Chandra Orion Ultradeep Project observed hundreds of young, low-mass
stars undergoing highly energetic X-ray flare events. The 32 most powerful
cases have been modeled with the result that the magnetic structures
responsible for these flares can be many stellar radii in extent. In this
paper, we model the observed spectral energy distributions of these 32 stars in
order to determine, in detail for each star, whether there is circumstellar
disk material situated in sufficient proximity to the stellar surface for
interaction with the large magnetic loops inferred from the observed X-ray
flares. Our spectral energy distributions span the wavelength range 0.3-8 um
(plus 24 um for some stars), allowing us to constrain the presence of dusty
circumstellar material out to >10 AU from the stellar surface in most cases.
For 24 of the 32 stars in our sample the available data are sufficient to
constrain the location of the inner edge of the dusty disks. Six of these (25%)
have spectral energy distributions consistent with inner disks within reach of
the observed magnetic loops. Another four stars may have gas disks interior to
the dust disk and extending within reach of the magnetic loops, but we cannot
confirm this with the available data. The remaining 14 stars (58%) appear to
have no significant disk material within reach of the large flaring loops.
Thus, up to ~40% of the sample stars exhibit energetic X-ray flares that
possibly arise from a magnetic star-disk interaction, and the remainder are
evidently associated with extremely large, free-standing magnetic loops
anchored only to the stellar surface.Comment: Accepted to the ApJ; 26 pages, 6 tables, 6 figure
Structural dynamics of RbmA governs plasticity of Vibrio cholerae biofilms
Biofilm formation is critical for the infection cycle of Vibrio cholerae. Vibrio exopolysaccharides (VPS) and the matrix proteins RbmA, Bap1 and RbmC are required for the development of biofilm architecture. We demonstrate that RbmA binds VPS directly and uses a binary structural switch within its first fibronectin type III (FnIII-1) domain to control RbmA structural dynamics and the formation of VPS-dependent higher-order structures. The structural switch in FnIII-1 regulates interactions in trans with the FnIII-2 domain, leading to open (monomeric) or closed (dimeric) interfaces. The ability of RbmA to switch between open and closed states is important for V. cholerae biofilm formation, as RbmA variants with switches that are locked in either of the two states lead to biofilms with altered architecture and structural integrity
Investigation on the Protective Effect of α-Mannan against the DNA Damage Induced by Aflatoxin B1 in Mouse Hepatocytes
Aflatoxin B1 is a contaminant of agricultural and dairy products that can be related to mutagenic and carcinogenic effects. In this report we explore the capacity of α-mannan (Man) to reduce the DNA damage induced by AFB1 in mouse hepatocytes. For this purpose we applied the comet assay to groups of animals which were first administered Man (100, 400 and 700 mg/kg, respectively) and 20 min later 1.0 mg/kg of AFB1. Liver cells were obtained at 4, 10, and 16 h after the chemical administration and examined. The results showed no protection of the damage induced by AFB1 with the low dose of the polysaccharide, but they did reveal antigenotoxic activity exerted by the two high doses. In addition, we induced a co-crystallization between both compounds, determined their fusion points and analyzed the molecules by UV spectroscopy. The obtained data suggested the formation of a supramolecular complex between AFB1 and Man
UBVRI Light Curves of 44 Type Ia Supernovae
We present UBVRI photometry of 44 type-Ia supernovae (SN Ia) observed from
1997 to 2001 as part of a continuing monitoring campaign at the Fred Lawrence
Whipple Observatory of the Harvard-Smithsonian Center for Astrophysics. The
data set comprises 2190 observations and is the largest homogeneously observed
and reduced sample of SN Ia to date, nearly doubling the number of
well-observed, nearby SN Ia with published multicolor CCD light curves. The
large sample of U-band photometry is a unique addition, with important
connections to SN Ia observed at high redshift. The decline rate of SN Ia
U-band light curves correlates well with the decline rate in other bands, as
does the U-B color at maximum light. However, the U-band peak magnitudes show
an increased dispersion relative to other bands even after accounting for
extinction and decline rate, amounting to an additional ~40% intrinsic scatter
compared to B-band.Comment: 84 authors, 71 pages, 51 tables, 10 figures. Accepted for publication
in the Astronomical Journal. Version with high-res figures and electronic
data at http://astron.berkeley.edu/~saurabh/cfa2snIa
The Dynamic X-ray Sky of the Local Universe
Over the next decade, we can expect time domain astronomy to flourish at
optical and radio wavelengths. In parallel with these efforts, a dedicated
transient "machine" operating at higher energies (X-ray band through soft
gamma-rays) is required to reveal the unique subset of events with variable
emission predominantly visible above 100 eV. Here we focus on the transient
phase space never yet sampled due to the lack of a sensitive, wide-field and
triggering facility dedicated exclusively to catching high energy transients
and enabling rapid coordinated multi-wavelength follow-up. We first describe
the advancements in our understanding of known X-ray transients that can only
be enabled through such a facility and then focus on the classes of transients
theoretically predicted to be out of reach of current detection capabilities.
Finally there is the exciting opportunity of revealing new classes of X-ray
transients and unveiling their nature through coordinated follow-up
observations at longer wavelengths.Comment: 8 pages, 2 figures; White Paper submitted to the Astro2010 SSE pane
Gene duplications and evolution of vertebrate voltage-gated sodium channels
Author Posting. © The Author(s), 2006. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Journal of Molecular Evolution 63 (2006): 208-221, doi:10.1007/s00239-005-0287-9.Voltage-gated sodium channels underlie action potential generation in excitable tissue.
To establish the evolutionary mechanisms that shaped the vertebrate sodium channel
a-subunit (SCNA) gene family and their encoded Nav1 proteins, we identified all SCNA
genes in several teleost species. Molecular cloning revealed that teleosts have eight
SCNA genes, comparable to the number in another vertebrate lineage, mammals.
Prior phylogenetic analyses had indicated that teleosts and tetrapods share four
monophyletic groups of SCNA genes and that tandem duplications selectively
expanded the number of genes in two of the four mammalian groups. However, the
number of genes in each group varies between teleosts and tetrapods suggesting
different evolutionary histories in the two vertebrate lineages. Our findings from
phylogenetic analysis and chromosomal mapping of Danio rerio genes indicate that
tandem duplications are an unlikely mechanism for generation of the extant teleost
SCNA genes. Instead, analysis of other closely mapped genes in D. rerio supports the
hypothesis that a whole genome duplication was involved in expansion of the SCNA
gene family in teleosts. Interestingly, despite their different evolutionary histories,
mRNA analyses demonstrated a conservation of expression patterns for SCNA
orthologues in teleosts and tetrapods, suggesting functional conservation.The authors’ work was supported by NIH grants (NS 38937; AEN,
ADT and ABR, NS 25513; HHZ and YL and NSF IBN 0236147; MCJ)
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