7,925 research outputs found
Can Horndeski Theory be recast using Teleparallel Gravity?
Horndeski gravity is the most general scalar tensor theory, with a single
scalar field, leading to second order field equations and after the GW170817 it
has been severely constrained. In this paper, we study the analogue of
Horndeski's theory in the teleparallel gravity framework were gravity is
mediated through torsion instead of curvature. We show that, even though, many
terms are the same as in the curvature case, we have much richer phenomenology
in the teleparallel setting because of the nature of the torsion tensor.
Moreover, Teleparallel Horndenski contains the standard Horndenski gravity as a
subcase and also contains many modified Teleparallel theories considered in the
past, such as gravity or Teleparallel Dark energy. Thus, due to the
appearing of a new term in the Lagrangian, this theory can explain dark energy
without a cosmological constant, may describe a crossing of the phantom
barrier, explain inflation and also solve the tension for , making it a
good candidate for a correct modified theory of gravity.Comment: 18 pages, 1 figur
Performance comparison of differential space-time signalling schemes for OFDM systems
Differential transmit diversity is an attractive alternative to its coherent counterpart, especially for multiple antenna systems where channel estimation is more difficult to attain compared to that of single antenna systems. In this paper we compare two different types of differential transmit diversity techniques for OFDM based transmissions. The first technique uses differential space-time block codes (DSTBC) from orthogonal designs and the second uses the differential cyclic delay diversity (DCDD). The results compare the bit error performance for several transmit antenna configurations. The results show that DCDD offers a very close performance to that of DSTBC, with the advantage of a simplified receiver structure
Self-reinoculation with fecal flora changes microbiota density and composition leading to an altered bile-acid profile in the mouse small intestine
Background: The upper gastrointestinal tract plays a prominent role in human physiology as the primary site for enzymatic digestion and nutrient absorption, immune sampling, and drug uptake. Alterations to the small intestine microbiome have been implicated in various human diseases, such as non-alcoholic steatohepatitis and inflammatory bowel conditions. Yet, the physiological and functional roles of the small intestine microbiota in humans remain poorly characterized because of the complexities associated with its sampling. Rodent models are used extensively in microbiome research and enable the spatial, temporal, compositional, and functional interrogation of the gastrointestinal microbiota and its effects on the host physiology and disease phenotype. Classical, culture-based studies have documented that fecal microbial self-reinoculation (via coprophagy) affects the composition and abundance of microbes in the murine proximal gastrointestinal tract. This pervasive self-reinoculation behavior could be a particularly relevant study factor when investigating small intestine microbiota. Modern microbiome studies either do not take self-reinoculation into account, or assume that approaches such as single housing mice or housing on wire mesh floors eliminate it. These assumptions have not been rigorously tested with modern tools. Here, we used quantitative 16S rRNA gene amplicon sequencing, quantitative microbial functional gene content inference, and metabolomic analyses of bile acids to evaluate the effects of self-reinoculation on microbial loads, composition, and function in the murine upper gastrointestinal tract.
Results: In coprophagic mice, continuous self-exposure to the fecal flora had substantial quantitative and qualitative effects on the upper gastrointestinal microbiome. These differences in microbial abundance and community composition were associated with an altered profile of the small intestine bile acid pool, and, importantly, could not be inferred from analyzing large intestine or stool samples. Overall, the patterns observed in the small intestine of non-coprophagic mice (reduced total microbial load, low abundance of anaerobic microbiota, and bile acids predominantly in the conjugated form) resemble those typically seen in the human small intestine.
Conclusions: Future studies need to take self-reinoculation into account when using mouse models to evaluate gastrointestinal microbial colonization and function in relation to xenobiotic transformation and pharmacokinetics or in the context of physiological states and diseases linked to small intestine microbiome and to small intestine dysbiosis
A Quantitative Sequencing Framework for Absolute Abundance Measurements of Mucosal and Lumenal Microbial Communities
A fundamental goal in microbiome studies is determining which microbes affect host physiology. Standard methods for determining changes in microbial taxa measure relative, rather than absolute abundances. Moreover, studies often analyze only stool, despite microbial diversity differing substantially among gastrointestinal (GI) locations. Here, we develop a quantitative framework to measure absolute abundances of individual bacterial taxa by combining the precision of digital PCR with the high-throughput nature of 16S rRNA gene amplicon sequencing. In a murine ketogenic-diet study, we compare microbial loads in lumenal and mucosal samples along the GI tract. Quantitative measurements of absolute (but not relative) abundances reveal decreases in total microbial loads on the ketogenic diet and enable us to determine the differential effects of diet on each taxon in stool and small-intestine mucosa samples. This rigorous quantitative microbial analysis framework, appropriate for diverse GI locations enables mapping microbial biogeography of the mammalian GI tract and more accurate analyses of changes in microbial taxa in microbiome studies
Probabilistic Perspectives on Collecting Human Uncertainty in Predictive Data Mining
In many areas of data mining, data is collected from humans beings. In this
contribution, we ask the question of how people actually respond to ordinal
scales. The main problem observed is that users tend to be volatile in their
choices, i.e. complex cognitions do not always lead to the same decisions, but
to distributions of possible decision outputs. This human uncertainty may
sometimes have quite an impact on common data mining approaches and thus, the
question of effective modelling this so called human uncertainty emerges
naturally.
Our contribution introduces two different approaches for modelling the human
uncertainty of user responses. In doing so, we develop techniques in order to
measure this uncertainty at the level of user inputs as well as the level of
user cognition. With support of comprehensive user experiments and large-scale
simulations, we systematically compare both methodologies along with their
implications for personalisation approaches. Our findings demonstrate that
significant amounts of users do submit something completely different (action)
than they really have in mind (cognition). Moreover, we demonstrate that
statistically sound evidence with respect to algorithm assessment becomes quite
hard to realise, especially when explicit rankings shall be built
Reviving Horndeski Theory using Teleparallel Gravity after GW170817
Horndeski gravity was highly constrained from the recent gravitational wave
observations by the LIGO Collaboration down to .
In this Letter we study the tensorial perturbations in a flat cosmological
background for an analogue version of Horndenki gravity which is based in
Teleparallel Gravity constructed from a flat manifold with a nonvanishing
torsion tensor. It is found that in this approach, one can construct a more
general Horndeski theory satisfying without eliminating the
coupling functions and that were highly constrained
in standard Horndeski theory. Hence, in the Teleparallel approach one is able
to restore these terms, creating an interesting way to revive Horndeski
gravity.Comment: 12 pages, 0 figure
A Decidable Confluence Test for Cognitive Models in ACT-R
Computational cognitive modeling investigates human cognition by building
detailed computational models for cognitive processes. Adaptive Control of
Thought - Rational (ACT-R) is a rule-based cognitive architecture that offers a
widely employed framework to build such models. There is a sound and complete
embedding of ACT-R in Constraint Handling Rules (CHR). Therefore analysis
techniques from CHR can be used to reason about computational properties of
ACT-R models. For example, confluence is the property that a program yields the
same result for the same input regardless of the rules that are applied.
In ACT-R models, there are often cognitive processes that should always yield
the same result while others e.g. implement strategies to solve a problem that
could yield different results. In this paper, a decidable confluence criterion
for ACT-R is presented. It allows to identify ACT-R rules that are not
confluent. Thereby, the modeler can check if his model has the desired
behavior.
The sound and complete translation of ACT-R to CHR from prior work is used to
come up with a suitable invariant-based confluence criterion from the CHR
literature. Proper invariants for translated ACT-R models are identified and
proven to be decidable. The presented method coincides with confluence of the
original ACT-R models.Comment: To appear in Stefania Costantini, Enrico Franconi, William Van
Woensel, Roman Kontchakov, Fariba Sadri, and Dumitru Roman: "Proceedings of
RuleML+RR 2017". Springer LNC
N,N′,N′′-TricycloÂhexylÂguanidinium iodide
In the title compound, C19H36N3
+·I−, the orientation of the cycloÂhexyl rings around the planar (sum of N—C—N angles = 360°) CN3
+ unit produces steric hindrance around the N—H groups. As a consequence of this particular orientation of the tricycloÂhexylÂguanidinium cation (hereafter denoted CHGH+), hydrogen bonding is restricted to classical N—H⋯I and non-clasical (cycloÂhexÂyl)C—H⋯I hydrogen bonds. The propeller CHGH+ cation and the oriented hydrogen-bonding interactions lead to a three-dimensional supraÂmolecular structure
Perlindungan Hukum Terhadap Anak Dalam Perspektif Hak Asasi Manusia
This study aims to analyze the problem of legal protection for children in the perspective of human rights. The type of this research is socio-juridical or including descriptive research with a non-doctrinal approach, which views law as a socio-empirical symptom observed in experience. The research method used is descriptive research with the type of incorporation of normative legal research with sociological legal research related to the implementation of legal protection for children in the perspective of human rights. The results of the study show that the results of this study are the legal protection of children in the perspective of human rights in essence is an effort made by parents, government and society to fulfill and guarantee all children's rights that have been guaranteed in the convention of children's rights and laws Number 35 of 2014 concerning Child Protection. Legal protection for children in the perspective of human rights is less implemented because the government has not implemented its obligations in fulfilling children's rights so that there are still legal violations of children. The recommendation of this research is to implement legal protection for children in the perspective of human rights, parents should be fully responsible for the behavior of children and the government establishes policies that are in line with the wishes of the community, so that the common perception between parents, government and society is realized in fulfilling the rights child
- …