1,191 research outputs found
Induced gravity on intersecting brane-worlds Part I: Maximally symmetric solutions
We explore models of intersecting brane-worlds with induced gravity terms on
codimension one branes and on their intersection. Maximally symmetric solutions
for the branes and the intersection are found. We find new self-accelerating
solutions. In a 6d spacetime, the solutions realize the see-saw modification of
gravity where the UV scale of the modification to 4d gravity is determined by
6d Planck scale given by eV and the IR scale of the
modification is determined by GeV where
is present-day Hubble scale. We find that it is increasingly difficult to
construct phenomenologically viable models in higher-dimensional spacetime due
to the necessity to have the lower value for the fundamental Planck scale to
realize the late time acceleration. It is found that the system also admits
self-tuning solutions where the tension at the intersection does not change the
geometry of the intersection. The induced gravity terms can avoid the necessity
to compactify the extra dimensions. Finally, we discuss the possibility to have
ordinary matter at the intersection, without introducing any regularisation,
using the induced gravity terms.Comment: 16 pages, some mistakes in the identification of the higher
codimensional singular structure corrected. Main results unchange
PROTOGNATHODUS (CONODONTA) AND ITS POTENTIAL AS A TOOL FOR DEFINING THE DEVONIAN/CARBONIFEROUS BOUNDARY
The current definition of the Devonian/Carboniferous boundary is the first occurrence of the conodont Siphonodella sulcata. Due to difficulties in identification of the early siphonodellids, such as S. praesulcata and S. sulcata, investigation of Protognathodus which enters in the latest Devonian and extends into the Mississippian, was undertaken to determine use as a better indicator of the base of the Carboniferous. During the D/C boundary interval, Protognathus is represented by four species: Pr. meischneri, Pr. collinsoni, Pr. kockeli and Pr. kuehni.Although Pr. kockeli can be abundant in boundary interval sections, none of the four Protognathodus species has a high potential as a tool for redefining the D/C boundary, based on regional variation in first occurrence data, restricted stratigraphic ranges and global distribution, poorly understood facies occurrences, as well as general rarity of the taxa.
Smooth tensionful higher-codimensional brane worlds with bulk and brane form fields
Completely regular tensionful codimension-n brane world solutions are
discussed, where the core of the brane is chosen to be a thin codimension-(n-1)
shell in an infinite volume flat bulk, and an Einstein-Hilbert term localized
on the brane is included (Dvali-Gabadadze-Porrati models). In order to support
such localized sources we enrich the vacuum structure of the brane by the
inclusion of localized form fields. We find that phenomenological constraints
on the size of the internal core seem to impose an upper bound to the brane
tension. Finite transverse-volume smooth solutions are also discussed.Comment: 1+14 pages, 2 figures; section 2.3 improved, typos corrected and
references added. Published versio
A systematic literature review on IoT-aware business process modeling views, requirements and notations
The Internet of things has been adopted in several sectors both influencing how people work and enhancing organizations' business processes. This resulted in the rise of relevant research topics such as IoT-aware business processes. The modeling of these processes makes it possible to better understand working scenarios and to support the adoption of model-driven development approaches for IoT-aware and process-oriented software systems. Since much research has been performed on this topic, a better awareness of the current status is needed. This paper reports a systematic literature review to develop a map on modeling notations for IoT-aware business processes. The survey mainly adopts an academic point of view, resulting in the detailed analysis of 84 research works from the leading computer science digital libraries. The output of the review is in the form of schemes and reflections. In particular, our research aims to shed light on (1) the relevant modeling views referring to different types of IoT-aware business processes; (2) the IoT requirements supported by the modeling notations; and (3) the modeling notations proposed and/or adopted to model IoT-aware business processes. Finally, our research work highlights possible future research lines needing further investigations
Stars in the Silurian sky: Echinoderm holdfasts from the Carnic Alps
A small collection of echinoderm holdfasts from the Ludlow Cardiola Formation of the Carnic Alps (Austria)
contains a wide range of morphologies as a response of environmental adaptation. In general, the holdfasts
have a globous and massive dome-like profile with several processes arranged in a sub-radial disposition, so to
create a sort of ‘star-like’ outline. A small central depression is common but not present on all specimens. The
distinctive holdfasts are preserved in an iron-rich phase, documenting a substitution that has also affected other
non-echinoderm calcareous material
Stars in the Silurian sky : Echinoderm holdfasts from the Carnic Alps, Austria
A small collection of echinoderm holdfasts from the Ludlow Cardiola Formation of the Carnic Alps (Austria) contains a wide range of morphologies as a response of environmental adaptation. In general, the holdfasts have a globous and massive dome-like profile with several processes arranged in a sub-radial disposition, so to create a sort of 'star-like' outline. A small central depression is common but not present on all specimens. The distinctive holdfasts are preserved in an iron-rich phase, documenting a substitution that has also affected other non-echinoderm calcareous material
orbifold compactifications in with Gauss-Bonnet term
We present a general setup for junctions of semi-infinite 4-branes in
with the Gauss-Bonnet term. The 3-brane tension at the junction of 4-branes can
be nonzero. Using the brane junctions as the origin of the discrete
rotation symmetry, we identify 3-brane tensions at three fixed points of the
orbifold in terms of the 4-brane tensions. As a result, the three
3-brane tensions can be simultaneously positive, which enables us to explain
the mass hierarchy by taking one of two branes apart from the hidden brane as
the visible brane, and hence does not introduce a severe cosmological problem.Comment: Latex file of 20 pages including 2 figure
First documentation of the Polygnathoides siluricus conodont Zone (Ludfordian) in South America (Argentina) and the stratigraphic significance of the younger species of Kockelella (Conodonta)
The coquinoid beds from the middle part of the Los Espejos Formation at the Poblete creek section (Talacasto Creek) yielded abundant conodonts. The genus Kockelella (Walliser) represents the most relevant biostratigraphical genus in this conodont fauna. The co-occurrence of Kockelella maenniki Serpagli and Corradini, Kockelella variabilis ichnusae Serpagli and Corradini, K. variabilis Walliser, Kockelella ortus sardoa (Serpagli & Corradini), and Kockelella ortus absidata (Barrick & Klapper) allow us to record for the first time the Polygnathoides siluricus Zone in South America, which suggests the Ludfordian Stage (late Ludlow). We also propose an accurate correlation of the Los Espejos Formation with the lower Ludfordian deposits from the Carnic Alps, Sardinia, Morocco, Czech Republic, Gotland, and North America.Fil: Gomez, Maria Jose. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Conicet - San Juan. Centro de Investigaciones de la Geosfera y Biosfera. Universidad Nacional de San Juan. Facultad de Ciencias Exactas FÃsicas y Naturales. Centro de Investigaciones de la Geosfera y Biosfera; ArgentinaFil: Mestre, Ana Paula. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Conicet - San Juan. Centro de Investigaciones de la Geosfera y Biosfera. Universidad Nacional de San Juan. Facultad de Ciencias Exactas FÃsicas y Naturales. Centro de Investigaciones de la Geosfera y Biosfera; ArgentinaFil: Garcias Paez, Yanina Vanesa. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Conicet - San Juan. Centro de Investigaciones de la Geosfera y Biosfera. Universidad Nacional de San Juan. Facultad de Ciencias Exactas FÃsicas y Naturales. Centro de Investigaciones de la Geosfera y Biosfera; ArgentinaFil: Corradini, Carlo. Università degli Studi di Cagliari; Itali
Localized gravity and mass hierarchy in D=6 with the Gauss-Bonnet term
We obtain the localized gravity on the intersection of two orthogonal
non-solitonic or solitonic 4-branes in D=6 in the presence of the Gauss-Bonnet
term. The tension of the intersection is allowed to exist unlike the case
without the Gauss-Bonnet term. We show that gravity could be confined to the
solitonic 4-branes for a particular choice of the Gauss-Bonnet coupling. If the
extra dimensions are compactified with the orbifold
symmetry, the mass hierarchy between the Planck scale and the weak scale can be
explained by putting our universe at the TeV intersection of positive tension
located at the orbifold fixed point.Comment: Latex file of 12 page
Molecular and clinical correlates in iron overload associated with mutations in ferroportin
Mutations in ferroportin (Fpn) result in iron overload. We correlate the behavior of three Fpn mutants in vitro with patients' phenotypes. Patients with Fpn mutations A77D or N174I showed macrophage iron loading. In cultured cells, FpnA77D did not reach the cell surface and cells did not export iron. Fpn mutant N1741 showed plasma membrane and intracellular localization, and did not transport iron. Fpn mutation G80S was targeted to the cell surface and was transport competent, however patients showed macrophage iron. We suggest that FpnG80S represents a class of Fpn mutants whose behavior in vitro does not explain the patients' phenotype
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