1,281 research outputs found
Depth and morphology of reflectors from the 2-D non-linear inversion of arrival-time and waveform semblance data: method and applications to synthetic data
We propose a two-dimensional, non-linear method for the inversion
of reflected/converted traveltimes and waveform semblance designed to obtain
the location and morphology of seismic reflectors in a lateral heterogeneous
medium and in any source-to-receiver acquisition lay-out. This method uses a
scheme of non-linear optimisation for the determination of the interface
parameters where the calculation of the traveltimes is carried out using a finite-
difference solver of the Eikonal equation, assuming an a priori known back-
ground velocity model. For the search of the optimal interface model, we have
used a multiscale approach and the Genetic Algorithm global optimization
technique. During the initial stages of inversion, we used the arrival times of the
reflection phase to retrieve the interface model that is defined by a small num-
ber of parameters. In the successive steps, the inversion is based on the opti-
mization of the semblance value determined along the calculated traveltime
curves. Errors in the final model parameters and the criteria for the choice of
the bestfit model are also estimated from the shape of the semblance function
in the model parameter space. The method is tested and validated on a synthe-
tic dataset that simulates the acquisition of reflection data in a complex volca-
nic structure
Investigating h-Prune activation of Wnt signalling in breast cancer
We have been investigating a novel link between two independent processes linked to breast cancer: Wnt signalling and h-Prune overexpression. The canonical Wnt signalling pathway was activated in 40% to 60% of human breast cancers through mechanisms that are not understood. Similarly, the phosphodiesterase h-Prune was overexpressed or amplified in 54% of breast cancers and was linked to breast tumour progression through unknown mechanisms.
We have shown that overexpression of xenopus Prune induced formation of a secondary axis in a standard assay to identify activators of the Wnt signalling pathway. In HEK293 cells, xenopus Prune overexpression induced a 300-fold increase in Wnt/TCF-dependent transcription. Whilst human prune does not appear to be able to activate Wnt signalling as potently as its xenopus homologue, it does synergise with other activators of the pathway to increase TCF-dependent transcription.
Here we show whether there is a correlation between overexpression of h-Prune and active Wnt signalling in breast cancer, and whether the synergistic responses described are mediated through the enzymatic activity of prune, or through binding to GSK-3
Feasibility study of a loss-driven earthquake early warning and rapid response systems for tunnels of the Italian high-speed railway network
PRUNE (prune exopolyphosphatase)
Short communication on PRUNE, with data on DNA/RNA, on the protein encoded and where the gene is implicated
Underwater acoustic channel properties in the Gulf of Naples and their effects on digital data transmission
In this paper we studied the physical properties of the Gulf of Naples (Southern Italy) for its use as a commu-
nication channel for the acoustic transmission of digital data acquired by seismic instruments on the seafloor to
a moored buoy. The acoustic link will be assured by high frequency acoustic modems operating with a central
frequency of 100 kHz and a band pass of 10 kHz. The main operational requirements of data transmission con-
cern the near horizontal acoustic link, the maximum depth of the sea being about 300 m and the planned hori-
zontal distance between seismic instruments and buoy 2 km. This study constructs the signal-to-noise ratio maps
to understand the limits beyond which the clarity of the transmission is no longer considered reliable. Using ray-
theory, we compute the amplitudes of a transmitted signal at a grid of 21×12 receivers to calculate the transmis-
sion loss at each receiver. The signal-to-noise ratio is finally computed for each receiver knowing also the trans-
mitter source level and the acoustic noise level in the Gulf of Naples. The results show that the multipath effects
predominate over the effects produced by the sound velocity gradient in the sea in the summer period. In the case
of omnidirectional transmitters with a Source Level (SL) of 165 dB and a baud rate of 2.4 kbit/s, the results al-
so show that distances of 1400-1600 m can be reached throughout the year for transmitter-receiver connections
below 50 m depth in the underwater acoustic channel
PRUNE1: a disease-causing gene for secondary microcephaly
In their Letter to the Editor, Karakaya et al. (2017) present
an interesting case report describing the clinical course
involving secondary microcephaly of a 3-year-old Turkish
boy found to be homozygous for a frameshift mutation in
PRUNE1 identified through whole exome sequencing. The
child presented with congenital hypotonia, contractures and
global developmental delay with respiratory insufficiency
and seizures developing in the first year of life. The authors
note that the affected child’s head circumference plotted on
the 75th centile at birth, and that by 38 months of age he
had developed microcephaly. Neuroimaging at 14 months
revealed cerebral and cerebellar atrophy consistent with
other patients described with Prune syndrome (Karaca
et al., 2015; Costain et al., 2017; Zollo et al., 2017).
Although the child had abnormal neurology from birth,
there was a period of early developmental regression.
Peripheral spasticity in the lower extremities and optic atrophy
were not documented until 38 months. In addition to
the PRUNE1 variant, Karakaya et al. also identified a
second homozygous variant in the CCDC14 gene in the
Turkish child’s whole exome sequencing data that, while
listed to have an allele count of 108 in the current Genome
Aggregation Database (gnomAD) release, is notably absent
in homozygous fashion (Lek et al., 2016). CCDC14 is
known to be expressed in human brain, reported to negatively
regulate centriole duplication and interact with proteins
previously associated with primary microcephaly
(Firat-Karalar et al., 2014). Thus, while it seems likely
that the homozygous PRUNE1 variant is primarily responsible
for the clinical presentation in the Turkish child, it is
impossible to determine whether there may be any phenotypical
contribution from this additional homozygous
sequence variant.
Recently, Costain et al. (2017) described a homozygous
consensus splice site variant in PRUNE1 (c.521-2A4G;
NM_021222.1) in a 2-year-old Oji-Cre male who presented
with congenital hypotonia and talipes, whose head circumference
was large at birth ( +3 standard deviations), but by
2 years and 2 months plotted on the 50th centile, with a
weight and height on the 95th and 75th centiles, respectively.
However, it should be noted that the child’s father
is macrocephalic ( +4 standard deviations), the published
clinical photographs at 2 years 5 months of age illustrate
bitemporal narrowing, a sloping forehead and large ears,
consistent with a developing microcephaly, and neuroimaging revealed cortical and cerebellar atrophy. He
developed respiratory insufficiency shortly after birth, and
infantile spasms in the first year of life (Costain et al., 2017).
It remains to be determined how the phenotypical outcomes
stemming from proposed loss-of-function mutations
defined by Karakaya et al. and Costain et al., relate to
missense mutations published by Karaca et al. and also
Zollo et al., which are likely to involve at least partial
gain-of-function outcomes in PRUNE1 activity. However,
as more cases are investigated and published, the phenotype
associated with autosomal recessive Prune neurodevelopmental
disorder, and the functional outcomes of
PRUNE1 mutation, are becoming clearer. It is now apparent
that while some patients have a small head at birth and
others a head circumference in the normal range, the key
component of the microcephaly is that it is progressive, and
associated with characteristic neuroimaging findings with a
thin or hypoplastic corpus callosum and cortical and cerebellar
atrophy developing in early childhood. Although all
patients with Prune syndrome described to date are neurologically
impaired from birth, there also appears to be a
neurodegenerative component with progression of the disorder.
In our manuscript, we described clinical overlap of
Prune syndrome with the neurodegenerative condition associated
with homozygous mutations in TBCD (Zollo et al.,
2017). TBCD encodes one of the five tubulin-specific chaperones
that are required for a/b-tubulin de novo heterodimer
formation and the disorder is characterized by
developmental regression, seizures, optic atrophy and secondary
microcephaly, cortical atrophy with delayed myelination,
cerebellar atrophy and thinned corpus callosum
(Edvardson et al., 2016; Flex et al., 2016; Miyake et al.,
2016; Pode-Shakked et al., 2017). The neurodegenerative
phenotype documented in the Turkish child by Karakaya
et al. further demonstrates the similarities with the TBCD
disorder and Prune syndrome, and confirms optic atrophy
to be a feature of Prune syndrome. Interestingly, it is also
becoming clear that respiratory insufficiency is a common
feature of Prune syndrome, having been documented by
Karakaya et al. and in the Oji-Cre child, as well as the
youngest affected Omani child described in our manuscript
Natural compounds for pediatric cancer treatment
There is a tremendous need in clinics to impair cancer progression through noninvasive therapeutic approaches. The use of natural compounds to achieve this is of importance to improve the quality of life of young patients during their treatments. This review will address the "status of the art" related to the potential of natural compounds that are undergoing investigation in combination with standard therapeutic protocols in preclinical and clinical studies and their importance for pediatric cancer treatment. The early studies of drug discovery of these natural compounds discussed here include the main targets, the cellular signaling pathways involved, and the potential modes of action. We also focus on some promising natural compounds that have shown excellent results in vitro and in vivo: Chebulagic acid, Apigenin, Norcantharidin, Saffron/Crocin, Parthenolide, Longikaurin E, Lupeol, Spongistatin 1, and Deoxy-variolin B. Additionally, we introduce the effects of several compounds from nutraceutical and functional foods, to underline their potential use as adjuvant therapies to improve therapeutic benefits. For this purpose, we have selected several compounds: Agaritine, Ganoderma and GL6 peptide, Diallyl trisulfide and Ajoene from garlic, Epigallocatechin gallate from green tea, Curcumin, Resveratrol, and Quercetin
Finding the extraordinary and creating the unexpected: Gnome and Genius combined in an entrepreneurial ethical heuristic
Purpose – This paper aims to present an integrated framework for ethical decision making in uncertain conditions, such as those of entrepreneurship. The model aims to build an exceptional ethical heuristic employable by entrepreneurs.
Design/methodology/approach – The theoretical framework is anchored to Aquinas’ theory of practical reason virtue, specifically its minor virtue gnome, and the Kantian faculty of genius or to better say its modus operandi. Thanks to the composition of these prima facie distant ontologies it is possible to build a ‘ready-to-use’ heuristic.
Findings – The paper through a philosophical discussion offers a ready-to-use heuristic that may help entrepreneurs and businesspersons when ‘navigating’ uncertain and troubled situations. In such situations, firstly it is important to recognize the ‘exceptionality’ of the situation, disregarding where necessary the ordinary criteria of judgment (an act directed by gnome). Secondly, a creative reconstruction of available knowledge able to re-shape the ‘rules of the game’ is needed (an act directed by PR but with connotations drawn from genius).
Research limitations/implications – The paper provides only a theoretical conceptualization of the heuristic model. However, the result is a ready-to-use heuristic rule for entrepreneurs, who work in uncertain and unclear conditions. Empirical validation of the framework can represent an opportunity for future research to test the operative impact of such an exceptional ethical heuristic.
Originality/value – Little attention has been dedicated to ethical decision making in the entrepreneurial setting built on a virtue ethics approach. This paper’s proposed model may represent an innovative alternative to strictly rational models for ethical decision making
Mechanical Systems: Symmetry and Reduction
Reduction theory is concerned with mechanical systems with symmetries. It constructs a
lower dimensional reduced space in which associated conservation laws are taken out and
symmetries are \factored out" and studies the relation between the dynamics of the given
system with the dynamics on the reduced space. This subject is important in many areas,
such as stability of relative equilibria, geometric phases and integrable systems
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