7,286 research outputs found
Conformal Prediction: a Unified Review of Theory and New Challenges
In this work we provide a review of basic ideas and novel developments about
Conformal Prediction -- an innovative distribution-free, non-parametric
forecasting method, based on minimal assumptions -- that is able to yield in a
very straightforward way predictions sets that are valid in a statistical sense
also in in the finite sample case. The in-depth discussion provided in the
paper covers the theoretical underpinnings of Conformal Prediction, and then
proceeds to list the more advanced developments and adaptations of the original
idea.Comment: arXiv admin note: text overlap with arXiv:0706.3188,
arXiv:1604.04173, arXiv:1709.06233, arXiv:1203.5422 by other author
Diatoms synthesize sterols by inclusion of animal and fungal genes in the plant pathway
Diatoms are ubiquitous microalgae that have developed remarkable metabolic plasticity and gene diversification. Here we report the first elucidation of the complete biosynthesis of sterols in the lineage. The study has been carried out on the bloom-forming species Skeletonema marinoi and Cyclotella cryptica that synthesise an ensemble of sterols with chemotypes of animals (cholesterol and desmosterol), plants (dihydrobrassicasterol and 24-methylene cholesterol), algae (fucosterol) and marine invertebrates (clionasterol). In both species, sterols derive from mevalonate through cyclization of squalene to cycloartenol by cycloartenol synthase. The pathway anticipates synthesis of cholesterol by enzymes of the phytosterol route in plants, as recently reported in Solanaceae. Major divergences stem from reduction of Δ24(28) and Δ24(25) double bonds which, in diatoms, are apparently dependent on sterol reductases of fungi, algae and animals. Phylogenetic comparison revealed a good level of similarity between the sterol biosynthetic genes of S. marinoi and C. cryptica with those in the genomes of the other diatoms sequenced so far
CO2-Induced Transcriptional Reorganization: Molecular Basis of Capnophillic Lactic Fermentation in Thermotoga neapolitana
Capnophilic lactic fermentation (CLF) is a novel anaplerotic pathway able to convert sugars to lactic acid (LA) and hydrogen using CO2 as carbon enhancer in the hyperthermophilic bacterium Thermotoga neapolitana. In order to give further insights into CLF metabolic networks, we investigated the transcriptional modification induced by CO2 using a RNA-seq approach. Transcriptomic analysis revealed 1601 differentially expressed genes (DEGs) in an enriched CO2 atmosphere over a total of 1938 genes of the T. neapolitana genome. Transcription of PFOR and LDH genes belonging to the CLF pathway was up-regulated by CO2 together with 6-phosphogluconolactonase (6PGL) and 6-phosphogluconate dehydratase (EDD) of the Entner–Doudoroff (ED) pathway. The transcriptomic study also revealed up-regulation of genes coding for the flavin-based enzymes NADH-dependent reduced ferredoxin:NADP oxidoreductase (NFN) and NAD-ferredoxin oxidoreductase (RNF) that control supply of reduced ferredoxin and NADH and allow energy conservation-based sodium translocation through the cell membrane. These results support the hypothesis that CO2 induces rearrangement of the central carbon metabolism together with activation of mechanisms that increase availability of the reducing equivalents that are necessary to sustain CLF. In this view, this study reports a first rationale of the molecular basis of CLF in T. neapolitana and provides a list of target genes for the biotechnological implementation of this process
Sound field control with hemi-cylindrical loudspeaker arrays
An acoustical model for the sound field generated by hemi-cylindrical loudspeaker arrays is presented and a method for beamforming with said arrays is derived. The sound field model is obtained by introducing two independent boundary conditions for the sound field of a single impinging plane wave. The model for the radiation from a single loudspeaker in the array is then obtained from the reciprocity principle. Various beam patterns are presented and the theoretically predicted sound field is evaluated as a function of frequency. The results are discussed and an experimental array prototype is presented
Quasinormal modes of black holes immersed in a strong magnetic field
We found quasinormal modes, both in time and frequency domains, of the Ernst
black holes, that is neutral black holes immersed in an external magnetic
field. The Ernst solution reduces to the Schwarzschild solution, when the
magnetic field vanishes. It is found that the quasinormal spectrum for massless
scalar field in the vicinity of the magnetized black holes acquires an
effective "mass" , where m is the azimuthal number and B is
parameter describing the magnetic field. We shall show that in the presence of
a magnetic field quasinormal modes are longer lived and have larger oscillation
frequencies. The perturbations of higher dimensional magnetized black holes by
Ortaggio and of magnetized dilaton black holes by Radu are considered.Comment: 5 pages, RevTe
Hearing: a pediatrician s approach
Hearing plays a fundamental role in a child s global development; however, some professionals do not realize how much they may contribute to mitigate the sequelae caused by hearing impairment. AIM: to collect data on pediatricians approaches in a city in the country side of Santa Catarina State, regarding the early detection of hearing impairment and identify the methodology utilized for its diagnosis. STUDY DESING: Historical Cohort with Cross-Sectional Cohort. MATERIALS AND METHODS: Analysis of questionnaires with nine multiple choice questions and ten open questions. RESULTS: 62% reported that their training in hearing disorders happened during their medical course; high risk patients are referred to the otorhinolaryngologist (92%); 83% said they are aware of the evaluation techniques; 55% stated they were not aware of the different types of hearing loss; only 25% reported they knew about the levels of hearing loss and 42% of the interviewees believe a child may have fruitful use of a hearing aid before six months of age. CONCLUSION: There is the need of more information about the importance of early diagnosis, as well as the methods used for this end.A audição exerce fundamental importância no desenvolvimento global da criança, porém, alguns profissionais desconhecem a contribuição que podem dar para reduzir ou minimizar as seqüelas deixadas por uma perda auditiva. OBJETIVO: Coletar dados referentes à conduta dos pediatras, de uma cidade do interior de Santa Catarina, frente à detecção precoce da deficiência auditiva e identificar a metodologia utilizada para o diagnóstico. FORMA DE ESTUDO: Coorte histórico com corte transversal. MATERIAL E MÉTODO: Análise de questionários, com dez questões abertas e nove fechadas. RESULTADOS: 62% informaram que sua formação sobre deficiência auditiva ocorreu durante a graduação; conduta nos casos de alto risco (92%) é o encaminhamento ao otorrinolaringologista; 83% referem conhecer as técnicas de avaliação, 55% afirmam desconhecer os tipos de perda auditiva, apenas 25% mencionam conhecer os graus de perda auditiva e 42% dos entrevistados acreditam que uma criança pode fazer uso da prótese auditiva antes dos seis meses. CONCLUSÃO: A necessidade de mais informações sobre a importância do diagnóstico precoce, bem como dos métodos utilizados para realização deste, mostrou-se evidente neste estudo.Universidade Tuiuti do ParanáUniversidade Federal de São Paulo (UNIFESP), Escola Paulista de Medicina (EPM)Universidade Tuiuti do Paraná Programa de Mestrado em Distúrbios da ComunicaçãoUniversidade Federal do ParanáUniversidade Tuiuti do Paraná Programa de Pós-Graduação em Distúrbios da ComunicaçãoUNIFESP, EPMSciEL
Multicolor observations of the Hubble Deep Field South
We present a deep multicolor (UBVIJsHKs) catalog of galaxies in the HDF-S,
based on observations obtained with the HST WFPC2 in 1998 and VLT-ISAAC in
1999. The photometric procedures were tuned to derive a catalog optimized for
the estimation of photometric redshifts. In particular we adopted a
``conservative'' detection threshold which resulted in a list of 1611 objects.
The behavior of the observed source counts is in general agreement with the
result of Casertano et al. (2000) in the HDF-S and Williams et al. (1996) in
the HDF-N, while the corresponding counts in the HDF-N provided by
Fernandez-Soto et al. (1999) are systematically lower by a factor 1.5 beyond
I_AB=26. After correcting for the incompleteness of the source counts, the
object surface density at I_AB<27.5 is estimated to be 220 per square arcmin,
providing an estimate of the Extragalactic Background Light in the I band
consistent with the work of Madau & Pozzetti(2000). The comparison between the
median V-I color in the HDF-North and South shows a significant difference
around I_AB~26, possibly due to the presence of large scale structure at z~1 in
the HDF-N. High-z galaxy candidates (90 U dropout and 17 B dropout) were
selected by means of color diagrams, down to a magnitude I_AB=27, with a
surface density of (21+-1) and (3.9+-0.9) per square arcmin, respectively. 11
EROs (with (I-K)_AB>2.7) were selected down to K_AB=24, plus 3 objects whose
upper limit to the Ks flux is still compatible with the selection criterion.
The corresponding surface density of EROs is (2.5+-0.8) per sq.arcmin
((3.2+-0.9) per sq.arcmin if we include the three Ks upper limits). They show a
remarkably non-uniform spatial distribution and are classified with roughly
equal fractions in the categories of elliptical and starburst galaxies.Comment: 36 pages Latex, with 12 PostScript figures. Accepted for publication
in Astronomical Journa
Linking haloes to galaxies: how many halo properties are needed?
Recent studies emphasize that an empirical relation between the stellar mass
of galaxies and the mass of their host dark matter subhaloes can predict the
clustering of galaxies and its evolution with cosmic time. In this paper we
study the assumptions made by this methodology using a semi-analytical model
(SAM). To this end, we randomly swap between the locations of model galaxies
within a narrow range of subhalo mass (M_infall). We find that shuffled samples
of galaxies have different auto-correlation functions in comparison with the
original model galaxies. This difference is significant even if central and
satellite galaxies are allowed to follow a different relation between M_infall
and stellar mass, and can reach a factor of 2 for massive galaxies at redshift
zero. We analyze three features within SAMs that contribute to this effect: a)
The relation between stellar mass and subhalo mass evolves with redshift for
central galaxies, affecting satellite galaxies at the time of infall. b) The
stellar mass of galaxies falling into groups and clusters at high redshift is
different from the mass of central galaxies at the same time. c) The stellar
mass growth for satellite galaxies after infall can be significant and depends
on the infall redshift and the group mass. We show that the above is true for
differing SAMs, and that the effect is sensitive to the treatment of dynamical
friction and stripping of gas in satellite galaxies. We find that by using the
FoF group mass at redshift zero in addition to M_infall, an empirical model is
able to accurately reproduce the clustering properties of galaxies. On the
other hand, using the infall redshift as a second parameter does not yield as
good results because it is less correlated with stellar mass. Our analysis
indicates that environmental processes are important for modeling the
clustering and abundance of galaxies. (Abridged)Comment: Accepted for publication in MNRAS, minor changes from version
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