651 research outputs found
Mass spectrum from stochastic Levy-Schroedinger relativistic equations: possible qualitative predictions in QCD
Starting from the relation between the kinetic energy of a free
Levy-Schroedinger particle and the logarithmic characteristic of the underlying
stochastic process, we show that it is possible to get a precise relation
between renormalizable field theories and a specific Levy process. This
subsequently leads to a particular cut-off in the perturbative diagrams and can
produce a phenomenological mass spectrum that allows an interpretation of
quarks and leptons distributed in the three families of the standard model.Comment: 8 pages, no figures. arXiv admin note: substantial text overlap with
arXiv:1008.425
L\'evy-Schr\"odinger wave packets
We analyze the time--dependent solutions of the pseudo--differential
L\'evy--Schr\"odinger wave equation in the free case, and we compare them with
the associated L\'evy processes. We list the principal laws used to describe
the time evolutions of both the L\'evy process densities, and the
L\'evy--Schr\"odinger wave packets. To have self--adjoint generators and
unitary evolutions we will consider only absolutely continuous, infinitely
divisible L\'evy noises with laws symmetric under change of sign of the
independent variable. We then show several examples of the characteristic
behavior of the L\'evy--Schr\"odinger wave packets, and in particular of the
bi-modality arising in their evolutions: a feature at variance with the typical
diffusive uni--modality of both the L\'evy process densities, and the usual
Schr\"odinger wave functions.Comment: 41 pages, 13 figures; paper substantially shortened, while keeping
intact examples and results; changed format from "report" to "article";
eliminated Appendices B, C, F (old names); shifted Chapters 4 and 5 (old
numbers) from text to Appendices C, D (new names); introduced connection
between Relativistic q.m. laws and Generalized Hyperbolic law
Autophagy in major human diseases
Autophagy is a core molecular pathway for the preservation of cellular and organismal homeostasis. Pharmacological and genetic interventions impairing autophagy responses promote or aggravate disease in a plethora of experimental models. Consistently, mutations in autophagy-related processes cause severe human pathologies. Here, we review and discuss preclinical data linking autophagy dysfunction to the pathogenesis of major human disorders including cancer as well as cardiovascular, neurodegenerative, metabolic, pulmonary, renal, infectious, musculoskeletal, and ocular disorders
Characterization and evolution of cell division and cell wall synthesis genes in the bacterial phyla Verrucomicrobia, Lentisphaerae, Chlamydiae and Planctomycetes and phylogenetic comparison with rRNA genes
In the past, studies on the relationships of the bacterial phyla Planctomycetes, Chlamydiae, Lentisphaerae, and
Verrucomicrobia using different phylogenetic markers have been controversial. Investigations based on 16S
rRNA sequence analyses suggested a relationship of the four phyla, showing the branching order Planctomycetes,
Chlamydiae, Verrucomicrobia/Lentisphaerae. Phylogenetic analyses of 23S rRNA genes in this study also
support a monophyletic grouping and their branching order—this grouping is significant for understanding
cell division, since the major bacterial cell division protein FtsZ is absent from members of two of the phyla
Chlamydiae and Planctomycetes. In Verrucomicrobia, knowledge about cell division is mainly restricted to the
recent report of ftsZ in the closely related genera Prosthecobacter and Verrucomicrobium. In this study, genes of
the conserved division and cell wall (dcw) cluster (ddl, ftsQ, ftsA, and ftsZ) were characterized in all verrucomicrobial
subdivisions (1 to 4) with cultivable representatives (1 to 4). Sequence analyses and transcriptional
analyses in Verrucomicrobia and genome data analyses in Lentisphaerae suggested that cell division is based on
FtsZ in all verrucomicrobial subdivisions and possibly also in the sister phylum Lentisphaerae. Comprehensive
sequence analyses of available genome data for representatives of Verrucomicrobia, Lentisphaerae, Chlamydiae,
and Planctomycetes strongly indicate that their last common ancestor possessed a conserved, ancestral type of
dcw gene cluster and an FtsZ-based cell division mechanism. This implies that Planctomycetes and Chlamydiae
may have shifted independently to a non-FtsZ-based cell division mechanism after their separate branchings
from their last common ancestor with Verrucomicrobia
Open Vocabulary Extreme Classification Using Generative Models
The extreme multi-label classification (XMC) task aims at tagging content with a subset of labels from an extremely large label set. The label vocabulary is typically defined in advance by domain experts and assumed to capture all necessary tags. However in real world scenarios this label set, although large, is often incomplete and experts frequently need to refine it. To develop systems that simplify this process, we introduce the task of open vocabulary XMC (OXMC): given a piece of content, predict a set of labels, some of which may be outside of the known tag set. Hence, in addition to not having training data for some labels-as is the case in zero-shot classification-models need to invent some labels on-the-fly. We propose GROOV, a fine-tuned seq2seq model for OXMC that generates the set of labels as a flat sequence and is trained using a novel loss independent of predicted label order. We show the efficacy of the approach, experimenting with popular XMC datasets for which GROOV is able to predict meaningful labels outside the given vocabulary while performing on par with state-of-the-art solutions for known labels
Multidisciplinary investigation on the catfish parasite Hamatopeduncularia Yamaguti, 1953 (Monogenoidea: Dactylogyridae): description of two new species from India, and phylogenetic considerations
Hamatopeduncularia was erected with Hamatopeduncularis arii as the type species. This genus comprises monogenoidean species mostly found as ectoparasites of marine catfishes belonging to the Ariidae. There is a significant taxonomic ambiguity among Hamatopeduncularia species due to their morphological similarity, but so far only a few morphological studies have succeeded in addressing interspecific variation and relationships. Moreover, little molecular data is available for this genus. A multidisciplinary, integrated study consisting of morphological, morphometric and molecular analyses was conducted on different species of Hamatopeduncularia recovered from the gills of two marine catfishes, Arius jella Day and Plicofollis dussumieri (Valenciennes). Five species of Hamatopeduncularia, two of which represent new species, were investigated: H. arii, H. elongatum, H. thalassini, H. madhaviae sp. nov. and H. bifida sp. nov. Phylogenetic analysis was performed using the 18S rDNA sequence as a molecular marker. The most important results of the present work are: (1) the multidisciplinary description of two novel species; (2) the multidisciplinary redescription of two species and of the type species of the genus; (3) the first molecular characterisation of 18S rDNA sequences of five species of genus Hamatopeduncularia; and (4) molecular support for the monophyly of the genus. http://zoobank.org/urn:lsid:zoobank.org:act:1333F4CC-E497-4D0A-AD7D-276D44AE6413 http://zoobank.org/urn:lsid:zoobank.org:act:43D18F75-6F4A-4F9B-8C00-6234E5BA652
Characterization of bacterial operons consisting of two tubulins and a kinesin-like gene by the novel Two-Step Gene Walking method
Tubulins are still considered as typical proteins of
Eukaryotes. However, more recently they have been
found in the unusual bacteria Prosthecobacter
(btubAB). In this study, the genomic organization
of the btub-genes and their genomic environment
were characterized by using the newly developed
Two-Step Gene Walking method. In all investigated
Prosthecobacters, btubAB are organized in a typical
bacterial operon. Strikingly, all btub-operons
comprise a third gene with similarities to kinesin
light chain sequences. The genomic environments
of the characterized btub-operons are always
different. This supports the hypothesis that this
group of genes represents an independent functional
unit, which was acquired by Prosthecobacter
via horizontal gene transfer. The newly developed
Two-Step Gene Walking method is based on
randomly primed polymerase chain reaction (PCR).
It presents a simple workflow, which comprises only
two major steps—a Walking-PCR with a single
specific outward pointing primer (step 1) and the
direct sequencing of its product using a nested
specific primer (step 2). Two-Step Gene Walking
proved to be highly efficient and was successfully
used to characterize over 20 kb of sequence not only
in pure culture but even in complex non-pure culture
samples
Solar UV-B Radiation Influences Carotenoid Accumulation of Tomato Fruit through Both Ethylene-Dependent and -independent Mechanisms
The effect of UV-B shielding on ethylene production in ripening tomato fruits and the contribution of
ethylene and UV-B radiation on carotenoid accumulation and profile during ripening were assessed
to get more insight about the interplay between these two regulatory factors. To this aim, rin and nor
tomato mutants, unable to produce ripening ethylene, and cv Ailsa Craig were cultivated under
control or UV-B depleted conditions until full fruit ripening. The significantly decreased ethylene
evolution following UV-B depletion, evident only in Ailsa Craig, suggested the requirement of
functional rin and nor genes for UVB-mediated ethylene production. Carotenoid content and profile
were found to be controlled by both ethylene and UV-B radiation. This latter influenced carotenoid
metabolism either in an ethylene-dependent or -independent way, as indicated by UVB-induced
changes also in nor and rin carotenoid content and confirmed by correlation plots between ethylene
evolution and carotenoid accumulation performed separately for control and UV-B shielded fruits. In
conclusion, natural UV-B radiation influences carotenoid metabolism in a rather complex way,
involving ethylene-dependent and -independent mechanisms, which seem to act in an antagonistic
way
Multilingual Autoregressive Entity Linking
We present mGENRE, a sequence-to- sequence system for the Multilingual Entity Linking (MEL) problem—the task of resolving language-specific mentions to a multilingual Knowledge Base (KB). For a mention in a given language, mGENRE predicts the name of the target entity left-to-right, token-by-token in an autoregressive fashion. The autoregressive formulation allows us to effectively cross-encode mention string and entity names to capture more interactions than the standard dot product between mention and entity vectors. It also enables fast search within a large KB even for mentions that do not appear in mention tables and with no need for large-scale vector indices. While prior MEL works use a single representation for each entity, we match against entity names of as many languages as possible, which allows exploiting language connections between source input and target name. Moreover, in a zero-shot setting on languages with no training data at all, mGENRE treats the target language as a latent variable that is marginalized at prediction time. This leads to over 50% improvements in average accuracy. We show the efficacy of our approach through extensive evaluation including experiments on three popular MEL benchmarks where we establish new state-of-the-art results. Source code available at https://github.com/facebookresearch/GENRE
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