269 research outputs found
Impact of woven fabric: Experiments and mesostructure-based continuum-level simulations
Woven fabric is an increasingly important component of many defense and commercial systems, including deployable structures, restraint systems, numerous forms of protective armor, and a variety of structural applications where it serves as the reinforcement phase of composite materials. With the prevalence of these systems and the desire to explore new applications, acomprehensive, computationally efficient model for the deformation of woven fabrics is needed. However, modeling woven fabrics is difficult due, inparticular, to the need to simulate the response both at the scale of the entire fabric and at the meso-level, the scale of the yarns that compose the weave. Here, we present finite elements for the simulation of the three- dimensional, high-rated eformation of woven fabric. We employ a continuum- level modeling technique that, through the use of an appropriate unit cell, captures the evolution of the mesostructure of the fabric without explicitly modeling every yarn. Displacement degrees of freedom and degrees of freedom representing the change in crimp amplitude of each yarn family fully determine the deformed geometry of the mesostructure of the fabric, which in turn provides, through the constitutive relations, the internal nodal forces. In order to verify the accuracy of the elements, instrumented ballistic impact experiments with projectile velocities of 22–550 m/s were conducted on single layers of Kevlar ® fabric. Simulations of the experiments demonstrate that the finite elements are capable of efficiently simulating large, complex structures
An Anthropological Study on the Importance of Incest Taboos Associated with Sinhalese Traditional Marriage Customs in Social Control (With special reference to Aruggammana)
Incest taboos are social ethics that create necessary control over sexual relations, marriage, and the family into which we are born. Marriages between brothers and sisters, parallel cousins, two generations, and blood relatives are all considered incest taboos. Sinhalese society has long used norms and values for social control. These incest taboo restrictions, along with family, marriage, and kinship, have played an important role in maintaining social control. The research problem addresses the loss of social control caused by the non-implementation of kinship, marriage rituals, and courtship restrictions in traditional Sinhalese society due to socio-cultural changes such as urbanization, commercialization, modernization, and westernization. The purpose of the research is to study the relationship between kinship restrictions and social control in marriage rituals. In Kegalle District, Galigamuwa Divisional Secretariat Division, No. 62 Aruggammana Gramaseva domain, a sample of 50 households, representing 15% of the 324 household units, was used for the research. As a descriptive study, data was collected through observation and structured interviews using judgment and random sampling. As the concept of kinship gradually disappeared, it was recognized that extended families made up a smaller percentage, 14%. Due to the increase in the number of nuclear families, extended marriages now account for 78%, while monogamous marriages account for 5%. Premarital sex has increased, with 88% of marriages being based on love, compared to the past. Overall, 10% of the area could be identified with incest taboos. Thus, it can be concluded that in order to control society, the personal control exerted by kinship, incest taboos, and marriage rituals must be re-established. To achieve this, programs should be organized to reaffirm the value of kinship relations and social values. Knowledge about the social values related to sexual and marital relations, especially among young children and youth, should be promoted. This can be effectively done in collaboration with schools and religious shrines
Devouring the Milky Way Satellites: Modeling Dwarf Galaxies with Galacticus
Dwarf galaxies are ubiquitous throughout the universe and are extremely sensitive to various forms of internal and external feedback. Over the last two decades, the census of dwarf galaxies in the Local Group and beyond has increased markedly. While hydrodynamic simulations (e.g., FIRE II, Mint Justice League) have reproduced the observed dwarf properties down to the ultrafaints, such simulations require extensive computational resources to run. In this work, we constrain the standard physical implementations in the semianalytic model Galacticus to reproduce the observed properties of the Milky Way satellites down to the ultrafaint dwarfs found in the Sloan Digital Sky Survey. We run Galacticus on merger trees from our high-resolution N-body simulation of a Milky Way analog. We determine the best-fit parameters by matching the cumulative luminosity function and luminosity-metallicity relation from both observations and hydrodynamic simulations. With the correct parameters, the standard physics in Galacticus can reproduce the observed luminosity function and luminosity-metallicity relation of the Milky Way dwarfs. In addition, we find a multidimensional match with half-light radii, velocity dispersions, and mass to light ratios at z = 0 down to M V ≤ −6 (L ≥ 104 L ⊙). In addition to successfully reproducing the properties of the z = 0 Milky Way satellite population, our modeled dwarfs have star formation histories that are consistent with those of the Local Group dwarfs
Subjective Crowd Disagreements for Subjective Data: Uncovering Meaningful CrowdOpinion with Population-level Learning
Human-annotated data plays a critical role in the fairness of AI systems,
including those that deal with life-altering decisions or moderating
human-created web/social media content. Conventionally, annotator disagreements
are resolved before any learning takes place. However, researchers are
increasingly identifying annotator disagreement as pervasive and meaningful.
They also question the performance of a system when annotators disagree.
Particularly when minority views are disregarded, especially among groups that
may already be underrepresented in the annotator population. In this paper, we
introduce \emph{CrowdOpinion}\footnote{Accepted for publication at ACL 2023},
an unsupervised learning based approach that uses language features and label
distributions to pool similar items into larger samples of label distributions.
We experiment with four generative and one density-based clustering method,
applied to five linear combinations of label distributions and features. We use
five publicly available benchmark datasets (with varying levels of annotator
disagreements) from social media (Twitter, Gab, and Reddit). We also experiment
in the wild using a dataset from Facebook, where annotations come from the
platform itself by users reacting to posts. We evaluate \emph{CrowdOpinion} as
a label distribution prediction task using KL-divergence and a single-label
problem using accuracy measures.Comment: Accepted for Publication at ACL 202
Galaxy And Mass Assembly: The xSAGA Galaxy Complement in Nearby Galaxy Groups
Groups of galaxies are the intermediate density environment in which much of
the evolution of galaxies is thought to take place. In spectroscopic redshift
surveys, one can identify these as close spatial redshift associations.
However, spectroscopic surveys will always be more limited in luminosity and
completeness than imaging ones. Here we combine the Galaxy And Mass Assembly
group catalogue with the extended Satellites Around Galactic Analogues (xSAGA)
catalogue of Machine Learning identified low-redshift satellite galaxies. We
find 1825 xSAGA galaxies within the bounds of the GAMA equatorial fields (m <
21), 1562 of which could have a counterpart in the GAMA spectroscopic catalogue
(m < 19.8). Of these, 1326 do have a GAMA counterpart with 974 below z=0.03
(true positives) and 352 above (false positives). By crosscorrelating the GAMA
group catalogue with the xSAGA catalogue, we can extend and characterize the
satellite content of GAMA galaxy groups. We find that most groups have <5 xSAGA
galaxies associated with them but richer groups may have more. Each additional
xSAGA galaxy contributes only a small fraction of the group's total stellar
mass (<<10%). Selecting GAMA groups that resemble the Milky Way halo, with a
few (<4) bright galaxies, we find xSAGA can add a magnitude fainter sources to
a group and that the Local Group does not stand out in the number of bright
satellites. We explore the quiescent fraction of xSAGA galaxies in GAMA groups
and find a good agreement with the literature.Comment: 11 pages, 13 Figures, 2 Tables, accepted by MNRA
A comparison of two tests for filarial antigenemia in areas in Sri Lanka and Indonesia with low-level persistence of lymphatic filariasis following mass drug administration
BACKGROUND: Filarial antigen tests are key tools for mapping the distribution of bancroftian filariasis and for detecting areas with persistent infections following mass drug administration (MDA). A recent study showed that the new Alere Filariasis Test Strip (FTS) has better analytical sensitivity than the BinaxNOW Filariasis card test (Card Test) for detecting circulating filarial antigen, and the FTS detected more positive results than the Card Test in a field study performed in a highly endemic area in Liberia. METHODS: The present study compared the performance of the FTS and the Card Test in community surveys that were conducted in southern Sri Lanka and in Indonesia (Central Java) in areas with low-level persistence of LF following multiple rounds of MDA with diethylcarbamazine plus albendazole. The studies were performed in densely populated semi-urban areas where Wuchereria bancrofti is transmitted by Culex quinquefasciatus. RESULTS: Antigenemia rates by FTS were 138Â % higher in the Sri Lanka study (43/852 vs. 18/852) and 21Â % higher in the Indonesia study (50/778 vs. 41/778) than antigenemia rates by Card Test. Antigenemia rates were significantly higher in males than in females and higher in adults than in children in both study sites. Although overall antigenemia rates and test scores were significantly higher by FTS than by Card Test in both study areas, rates in young children were similar with both tests in both areas. CONCLUSIONS: These results extend the previously reported superior sensitivity of the FTS to areas with low residual infection rates following MDA, and this could affect mapping and post-MDA survey results in adults. However, our findings suggest that results of transmission assessment surveys (TAS) performed in school-aged children are likely to be similar with both tests
Neglected Patients with a Neglected Disease? A Qualitative Study of Lymphatic Filariasis
Lymphatic filariasis (LF) is a tropical disease causing extreme swelling of the limbs and male genitals. Despite recent successes in preventing transmission of the disease, some 40 million people worldwide who already have the disease have been largely neglected. We aimed to increase understanding of how this vulnerable, neglected group can be helped, by asking people with LF in Sri Lanka to recount their own experiences
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