5,425 research outputs found
Comparison of Gaussian process modeling software
Gaussian process fitting, or kriging, is often used to create a model from a
set of data. Many available software packages do this, but we show that very
different results can be obtained from different packages even when using the
same data and model. We describe the parameterization, features, and
optimization used by eight different fitting packages that run on four
different platforms. We then compare these eight packages using various data
functions and data sets, revealing that there are stark differences between the
packages. In addition to comparing the prediction accuracy, the predictive
variance--which is important for evaluating precision of predictions and is
often used in stopping criteria--is also evaluated
The structure and radiation spectra of illuminated accretion discs in AGN. I. Moderate illumination
We present detailed computations of the vertical structure of an accretion
disc illuminated by hard X-ray radiation with the code {\sc titan-noar}
suitable for Compton thick media. The energy generated via accretion is
dissipated partially in the cold disc as well as in the X-ray source. We study
the differences between the case where the X-ray source is in the form of a
lamp post above the accretion disc and the case of a heavy corona. We consider
radiative heating via Comptonization together with heating via photo-absorption
on numerous heavy elements as carbon, oxygen, silicon, iron. The transfer in
lines is precisely calculated. A better description of the heating/cooling
through the inclusion of line transfer, a correct description of the
temperature in the deeper layers, a correct description of the entire disc
vertical structure, as well as the study of the possible coronal pressure
effect, constitute an improvement in comparison to previous works. We show that
exact calculations of hydrostatic equilibrium and determination of the disc
thickness has a crucial impact on the optical depth of the hot illuminated
zone. We assume a moderate illumination where the viscous flux equals the X-ray
radiation flux. A highly ionized skin is created in the lamp post model, with
the outgoing spectrum containing many emission lines and ionization edges in
emission or absorption in the soft X-ray domain, as well as an iron line at
keV consisting of a blend of low ionization line from the deepest
layers and hydrogen and helium like resonance line from the upper layers, and
almost no absorption edge, contrary to the case of a slab of constant density.A
full heavy corona completely suppresses the highly ionized zone on the top of
the accretion disc and in such case the spectrum is featureless.Comment: 16 pages, 20 figures, corrected two sentences, accepted by MNRA
INITIAL CHARACTERIZATION OF MAJOR HISTOCOMPATIBILITY COMPLEX (MHC) CLASS IIB EXON 2 IN AN ENDANGERED RATTLESNAKE, THE EASTERN MASSASAUGA (SISTRURUS CATENATUS)
Genes of the major histocompatibility complex (MHC) play an important role in the vertebrate immune system and exhibit remarkably high levels of polymorphism, maintained by strong balancing selection. While the conservation implications of MHC variation have been explored in a variety of vertebrates, non-avian reptiles (most notably snakes) have received less attention. To address this gap and take the first steps toward more extensive population-level analyses, we cloned and sequenced MHC IIB exon 2 in an endangered rattlesnake, the Eastern Massasauga (Sistrurus catenatus). Based on three individuals, we found evidence of at least four putatively functional loci. These sequences exhibited relatively high levels of variation and significantly higher rates of nonsynonymous to synonymous substitutions, especially within the antigen-binding sites, indicating strong positive selection. Phylogenetic analysis revealed a pattern of trans-species polymorphism, also suggesting positive selection. These results contribute to our understanding of MHC variation in non-avian reptiles and form a basis for more studies of MHC variation in snakes of conservation concern
Obscuration model of Variability in AGN
There are strong suggestions that the disk-like accretion flow onto massive
black hole in AGN is disrupted in its innermost part (10-100 Rg), possibly due
to the radiation pressure instability. It may form a hot optically thin quasi
spherical (ADAF) flow surrounded by or containing denser clouds due to the
disruption of the disk. Such clouds might be optically thick, with a Thompson
depth of order of 10 or more. Within the frame of this cloud scenario
(Collin-Souffrin et al. 1996, Czerny & Dumont 1998), obscuration events are
expected and the effect would be seen as a variability. We consider expected
random variability due to statistical dispersion in location of clouds along
the line of sight for a constant covering factor. We discuss a simple
analytical toy model which provides us with the estimates of the mean spectral
properties and variability amplitude of AGN, and we support them with radiative
transfer computations done with the use of TITAN code of Dumont, Abrassart &
Collin (1999) and NOAR code of Abrassart (1999).Comment: to appear in Proc. of 5th Compton Symposium on Gamma-Ray Astronomy
and Astrophysic
Inclusive Local and Online Resources to Stay Active During the COVID-19 Pandemic
The COVID-19 pandemic has interrupted daily life in an innumerable amount of ways. Through gym closures and overcrowded, unsafe public spaces, maintaining exercise routines and reaching physical activity recommendations is increasingly difficult for many people. As a result of this, there has been an increasing emphasis on at home exercise and routines people can do at home. However, many of these resources are not inclusive of populations such as the elderly, people with disabilities, and the otherwise deconditioned as the exercises can be too strenuous or require specific equipment. The goal of this project was to compile a list of online and local resources in the Greater Burlington Area to help facilitate physical activity for all populations during the COVID-19 pandemic, and to include a short, intuitive walkthrough of a few exercises that can be done from the home in a chair.https://scholarworks.uvm.edu/fmclerk/1709/thumbnail.jp
Why activists seek psychotherapy
This exploratory study aimed to identify reasons why people who identify as activists seek psychotherapy. The literature on social movements supports the claim that activists are highly motivated individuals who seek to create meaning through work to promote social change, and as a result are exposed to a complex array of social forces that are institutional and interpersonal. As a collective social behavior, involvement in social movements allows activists to develop strong relationships with others while also becoming exposed to the risks of conflict and disapproval of others. Given that these relational factors and the nature of their organizing work can create a variety of stressors for activists, the researcher devised research questions that sought to explore whether there are common factors, themes, or presenting problems when accessing a therapist. The researcher presents findings from twelve semi-structured interviews with people who self-identify as activists and have participated in a social movement organization and psychotherapy within the last two years. The study\u27s findings illustrate the highly meaningful nature of developing an activist identity for participants; conscientious and perfectionistic personality traits among participants; a variety of healthful and conflictual interpersonal dynamics participants have experienced through their work; the importance of hard work; the prevalence of eating disorders, compulsive behaviors, and experiential avoidance when seeking treatment. A broad theme of participants stretching their resources so thin such that when a confounding problem arises in their lives, psychotherapy functions as a useful resource; and that activism is an important topic in therapy, though it is not discussed with the same level of depth with therapists as much as it is within friend networks. This study\u27s findings have the potential to promote development of interventions to treat symptoms seen in activists, education of psychotherapists on what issues are salient to activists when seeking treatment, and empowerment of activists in their work to promote social justice and social change. To promote the capacity of activists aligns with social work values that promote empowerment and social justice. As such, the study indicates the importance of clinical social workers and therapists to validate and affirm the meaning of activism in their clients\u27 lives
Combining community-based research and local knowledge to confront asthma and subsistence-fishing hazards in Greenpoint/Williamsburg, Brooklyn, New York.
Activists in the environmental justice movement are challenging expert-driven scientific research by taking the research process into their own hands and speaking for themselves by defining, analyzing, and prescribing solutions for the environmental health hazards confronting communities of the poor and people of color. I highlight the work of El Puente and The Watchperson Project--two community-based organizations in the Greenpoint/Williamsburg neighborhood in Brooklyn, New York, that have engaged in community-based participatory research (CBPR) to address asthma and risks from subsistence-fish diets. The CBPR process aims to engage community members as equal partners alongside scientists in problem definition, information collection, and data analysis--all geared toward locally relevant action for social change. In the first case I highlight how El Puente has organized residents to conduct a series of asthma health surveys and tapped into local knowledge of the Latino population to understand potential asthma triggers and to devise culturally relevant health interventions. In a second case I follow The Watchperson Project and their work surveying subsistence anglers and note how the community-gathered information contributed key data inputs for the U.S. Environmental Protection Agency Cumulative Exposure Project in the neighborhood. In each case I review the processes each organization used to conduct CBPR, some of their findings, and the local knowledge they gathered, all of which were crucial for understanding and addressing local environmental health issues. I conclude with some observations about the benefits and limits of CBPR for helping scientists and communities pursue environmental justice
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