2,604 research outputs found
Correlating Data Which Fit the Gompertz Equation of Growth
The Gompertz equation describes the decay of biological systems in which the rate of decrease of the concentration of an organism varies directly with its concentration and inversely with the concentration of an inhibitor. The inhibitor concentration falls exponentially with time. Four methods are compared for correlating data on the destruction of Ascites tumor cells which fit the Gompertz equation: analytical, graphical, analog computer, and digital computer
SDSS Observations of Kuiper Belt Objects: Colors and Variability
Colors of Trans Neptunian Objects (TNOs) are used to study the evolutionary
processes of bodies in the outskirts of the Solar System, and to test theories
regarding their origin. Here I describe a search for serendipitous Sloan
Digital Sky Survey (SDSS) observations of known TNOs and Centaurs. I present a
catalog of SDSS photometry, colors and astrometry of 388 measurements of 42
outer Solar-System objects. I find a weak evidence, at the ~2-sigma level (per
trial), for a correlation between the g-r color and inclination of scattered
disk objects and hot classical KBOs. I find a correlation between the g-r color
and the angular momentum in the z direction of all the objects in this sample.
Light curves as a function of phase angle are constructed for 13 objects. The
steepness of the slopes of these light curves suggests that the coherent
backscatter mechanism plays a major role in the reflectivity of outer
Solar-System small objects at small phase angles. I find a weak evidence for an
anti-correlation, significant at the 2-sigma confidence level (per trial),
between the g-band phase angle slope parameter and the semi-major axis, as well
as the aphelion distance, of these objects. I discuss the origin of this
possible correlation and argue that if this correlation is real it probably
indicates that "Sedna"-like objects have a different origin than other classes
of TNOs. Finally, I identify several objects with large variability amplitudes
(abridged).Comment: 8 pages, ApJ in pres
The Role of Genomic Data in the Discovery, Annotation and Evolutionary Interpretation of the Interferon-Lambda Family
Type-I interferons, type-II interferons, and the IL-10 family are helical cytokines with similar three-dimensional folds. However, their homologous relationship is difficult to detect on the basis of sequence alone. We have previously described the discovery of the human type-III interferons (IFN lambda-1, -2, -3 or IL-29, IL-28A, IL-28B), which required a combination of manual and computational techniques applied to predicted protein sequences.Here we describe how the use of gene structure analysis and comparative genomics enabled a more extensive understanding of these genes early in the discovery process. More recently, additional mammalian genome sequences have shown that there are between one and potentially nine copies of interferon lambda genes in each genome, and that several species have single exon versions of the interferon lambda gene.The variable number of single exon type-I interferons in mammals, along with recently identified genes in zebrafish homologous to interferons allows a story of interferon evolution to be proposed. This model suggests that the gene duplications and single exon retrotransposons of mammalian type-III interferons are positively selected for within a genome. These characteristics are also shared with the fish interferons and could be responsible for the generation of the IL10 family and also the single exon type-I interferons
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Dialogismo En El Cancionero De Miguel De Unamuno: Dialéctica De La Voz Poética
The present research is centered on Miguel de Unamuno's Songbook which is studied through the prism of the theory of dialogism elaborated by Mikhail Bakhtin. This study overcomes the limitation of Bakhtin's theory which extends solely to narrative genres, and argues that dialogism can also be applied to poetry. In this thesis I seek to rectify the critical oversight of this significant and original work of Unamuno and show that Songbook has panoply of innovative techniques aimed at creating the multiple poetic voices and dialogical interaction. Strong links are established between Bakhtin's theory, Unamuno's aesthetics and the postmodernist episteme of "the death of the author" which heralds the new era of fiction writing. I give a detailed analysis of Songbook's poetry based on Bakhtin's theory and incorporate the pragmalinguistic view of poetic discourse as a communicative act that involves a constant interaction between the addresser and the addressees. I find different types of dialogical expression in accordance with the number and the nature of different addressees at which the poet aims his discourse. This study shows that poetic tools forged by Unamuno are born of the need to express a conflictive inner world that is opposed to any type of dogmatism and monologism. Through the detailed analysis of the poetic discourse of Songbook it is demonstrated that Unamuno's innovations and experimentalism confer him a position of the precursor of postmodernism
Interrogating Fabry-Perot ultrasound sensors with Bessel beams for photoacoustic imaging
Photoacoustic Tomography (PAT) systems based on Fabry-Perot (FP) sensors provide high-resolution images limited by the system’s sensitivity. The sensitivity is limited by the optical Q-factor of the FP cavity (i.e., the optical confinement of the interrogation laser beam in the FP cavity). In existing systems, a focussed Gaussian beam is used to interrogate the sensor. While providing a small acoustic element required for high-resolution imaging, this interrogation beam naturally diverges inside the FP cavity, leading to the current sensitivity limit. To break this limit, a new approach of interrogating the FP sensor using a Bessel beam is investigated. The Noise Equivalent Pressure (NEP) and both axial and lateral PAT resolutions using Bessel beam interrogation were quantified. Bessel beam interrogation provided lower NEP, similar axial resolution, but lower lateral resolution. Thus, Bessel beam might be an alternative interrogation scheme for deep PAT imaging as high sensitivity is needed and the lateral resolution is limited by the aperture of the PAT system
Climate warming, marine protected areas and the ocean-scale integrity of coral reef ecosystems
Coral reefs have emerged as one of the ecosystems most vulnerable to climate variation and change. While the contribution
of a warming climate to the loss of live coral cover has been well documented across large spatial and temporal scales, the
associated effects on fish have not. Here, we respond to recent and repeated calls to assess the importance of local
management in conserving coral reefs in the context of global climate change. Such information is important, as coral reef
fish assemblages are the most species dense vertebrate communities on earth, contributing critical ecosystem functions
and providing crucial ecosystem services to human societies in tropical countries. Our assessment of the impacts of the
1998 mass bleaching event on coral cover, reef structural complexity, and reef associated fishes spans 7 countries, 66 sites
and 26 degrees of latitude in the Indian Ocean. Using Bayesian meta-analysis we show that changes in the size structure,
diversity and trophic composition of the reef fish community have followed coral declines. Although the ocean scale
integrity of these coral reef ecosystems has been lost, it is positive to see the effects are spatially variable at multiple scales,
with impacts and vulnerability affected by geography but not management regime. Existing no-take marine protected areas
still support high biomass of fish, however they had no positive affect on the ecosystem response to large-scale disturbance.
This suggests a need for future conservation and management efforts to identify and protect regional refugia, which should
be integrated into existing management frameworks and combined with policies to improve system-wide resilience to
climate variation and change
Autopsy in adults with congenital heart disease (ACHD).
The adult congenital heart diseases (ACHD) population is exceeding the pediatric congenital heart diseases (CHD) population and is progressively expanding each year, representing more than 90% of patients with CHD. Of these, about 75% have undergone surgical and/or percutaneous intervention for palliation or correction. Autopsy can be a very challenging procedure in ACHD patients. The approach and protocol to be used may vary depending on whether the pathologists are facing native disease without surgical or percutaneous interventions, but with various degrees of cardiac remodeling, or previously palliated or corrected CHD. Moreover, interventions for the same condition have evolved over the last decades, as has perioperative myocardial preservations and postoperative care, with different long-term sequelae depending on the era in which patients were operated on. Careful clinicopathological correlation is, thus, required to assist the pathologist in performing the autopsy and reaching a diagnosis regarding the cause of death. Due to the heterogeneity of the structural abnormalities, and the wide variety of surgical and interventional procedures, there are no standard methods for dissecting the heart at autopsy. In this paper, we describe the most common types of CHDs that a pathologist could encounter at autopsy, including the various types of surgical and percutaneous procedures and major pathological manifestations. We also propose a practical systematic approach to the autopsy of ACHD patients
Measures of Fluid Loss during Surfing: A Preliminary Analysis in Recreational Surfers
Surfing is a popular sport, but little is known about the extent to which recreational surfers experience fluid loss from this activity. The principal objective of this research was to estimate fluid loss during a surfing session through changes in pre- to post-session urine color (Ucol), urine osmolality (Uosm), and body mass (BM). Data were collected from 11 recreational surfers across 14 surf sessions conducted under various environmental (mean water temperature = 22.1 SD ± 2.3; range = 20-26oC; air temperature range = 13.1-31.5oC; relative humidity range = 37.5-88.1%) and surfing conditions (e.g. winter/summer, wave type, location, environmental and water conditions). Linear mixed effects models indicated that participants experienced significant pre- to post-session changes in BM (p \u3c 0.001), but not in Ucol or Uosm. These findings suggested that recreational surfers may experience fluid loss (measured by pre- to post-surfing BM) that may impact on their performance and health, and therefore they should adopt a hydration strategy to minimize this impact
Characterisation of candidate members of (136108) Haumea's family
Ragozzine & Brown [2007] presented a list of candidate members of the first
collisional family to be found among the trans-Neptunian Objects (TNOs), the
one associated with (136108) Haumea (2003 EL61). We aim to identify which of
the candidate members of the Haumea collisional family are true members, by
searching for water ice on their surfaces. We also attempt to test the theory
that the family members are made of almost pure water ice by using optical
light-curves to constrain their densities. We use optical and near-infrared
photometry to identify water ice, in particular using the (J - H_S) colour as a
sensitive measure of the absorption feature at 1.6 micron. We use the CH_4
filter of the new Hawk-I instrument at the VLT as a short H-band (H_S) for this
as it is more sensitive to the water ice feature than the usual H filter. We
report colours for 22 candidate family members, including NIR colours for 15.
We confirm that 2003 SQ317 and 2005 CB79 are family members, bringing the total
number of confirmed family members to 10. We reject 8 candidates as having no
water ice absorption based on our Hawk-I measurements, and 5 more based on
their optical colours. The combination of the large proportion of rejected
candidates and time lost to weather prevent us from putting strong constraints
on the density of the family members based on the light-curves obtained so far;
we can still say that none of the family members (except Haumea) require a
large density to explain their light-curve.Comment: 9 pages, 5 figures, accepted for publication in A&
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