690 research outputs found
Fast Frame-Based Image Deconvolution Using Variable Splitting and Constrained Optimization
We propose a new fast algorithm for solving one of the standard formulations
of frame-based image deconvolution: an unconstrained optimization problem,
involving an data-fidelity term and a non-smooth regularizer. Our
approach is based on using variable splitting to obtain an equivalent
constrained optimization formulation, which is then addressed with an augmented
Lagrangian method. The resulting algorithm efficiently uses a regularized
version of the Hessian of the data fidelity term, thus exploits second order
information. Experiments on a set of image deblurring benchmark problems show
that our algorithm is clearly faster than previous state-of-the-art methods.Comment: Submitted to the 2009 IEEE Workshop on Statistical Signal Processin
Metabolic plasticity for subcutaneous fat accumulation in a long-distance migratory bird traced by 2 H 2 O
The migrant black-tailed godwit (Limosa limosa) traditionally used natural wetlands in the Iberian Peninsula to prepare for migratory flights by feeding mainly in estuaries. In recent decades, this species has become increasingly dependent on rice fields, thereby relying on a plant-based diet for fuelling. Dietary fatty acids (FA) seem to be determinant to the composition of accumulated subcutaneous fat in migratory birds. It is still unclear whether metabolic plasticity allows for modification and/or synthesis of FA, contributing to a lipid profile that enables a successful migratory performance. Deuterated water was administered to captive black-tailed godwits submitted to two diets (fly larvae versus rice) and the incorporation of deuterium (2H) into subcutaneous triglycerides was analyzed by NMR. A recently developed localized biopsy method for sampling subcutaneous fat was employed with later successful release of all birds into the wild. The average chemical structure reflected mostly a mixture of saturated and monounsaturated 16- and 18-carbon FA, a profile frequently found in migrant birds. Significantly higher levels of polyunsaturated FA, as well as detectable levels of n-3 FA, were observed in fly-larvae-fed birds. Excess 2H-enrichments in FA revealed significantly higher rates of fractional de novo lipogenesis and FA desaturation capacity in rice-fed birds. This novel and non-lethal tracer method revealed the capacity of this species to alter its lipid metabolism to compensate for a poorer dietary lipid contribution. Because of its versatility, adapting this method to other scenarios and/or other migratory species is considered feasible and cost-effective.The authors acknowledge financial support from Fundacao para a Ciencia e Tecnologia (FCT) in the form of fellowships to I.V. (SFRH/BPD/90032/2012), P.M.A. (SFRH/BD/69238/2010), A.D.R. (SFRH/BD/74228/2010) and J.A.A. (SFRH/BPD/91527/2012) and research project EXCL/DTP-PIC/0069/2012. NMR data were collected at the UC-NMR facility that is supported by FEDER and FCT (RECI/QEQ-QFI/0168/2012, CENTRO-07-CT62-FEDER-002012) and Rede Nacional de Ressonancia Magnetica Nuclear (RNRMN).Peer Reviewe
Relationship of arterial and exhaled CO2 during elevated artificial pneumoperitoneum pressure for introduction of the first trocar.
The present study evaluated the correlation between arterial CO2 and exhaled CO2 during brief high-pressure pneumoperitoneum. Patients were randomly distributed into two groups: P12 group (n=30) received a maximum intraperitoneal pressure of 12mmHg, and P20 group (n=37) received a maximum intraperitoneal pressure of 20mmHg. Arterial CO2 was evaluated by radial arterial catheter and exhaled CO2 was measured by capnometry at the following time points: before insufflation, once intraperitoneal pressure reached 12mmHg , 5 minutes after intraperitoneal pressure reached 12mmHg for the P12 group or 20mmHg for the P20 group, and 10 minutes after intraperitoneal pressure reached 12mmHg for the P12 group or when intraperitoneal pressure had decreased from 20mmHg to 12mmHg, for the P20 group. During brief durations of very high intraperitoneal pressure (20mmHg), there was a strong correlation between arterial CO2 and exhaled CO2. Capnometry can be effectively used to monitor patients during transient increases in artificial pneumoperitoneum pressure
The dual role of starburst and active galactic nuclei in driving extreme molecular outflows
We report molecular gas observations of IRAS 20100-4156 and IRAS 03158+4227,
two local ultraluminous infrared galaxies (ULIRGs) hosting some of the fastest
and most massive molecular outflows known. Using ALMA and PdBI observations, we
spatially resolve the CO(1-0) emission from the outflowing molecular gas in
both and find maximum outflow velocities of and km/s for IRAS 20100-4156 and IRAS 03158+4227, respectively. We find total
gas mass outflow rates of and Msun/yr,
respectively, corresponding to molecular gas depletion timescales and Myr. This is nearly 3 times shorter than
the depletion timescales implied by star formation, and Myr, respectively. To determine the outflow driving
mechanism, we compare the starburst () and AGN ()
luminosities to the outflowing energy and momentum fluxes, using mid-infrared
spectral decomposition to discern . Comparison to other molecular
outflows in ULIRGs reveals that outflow properties correlate similarly with
and as with , indicating that AGN luminosity
alone may not be a good tracer of feedback strength and that a combination of
AGN and starburst activity may be driving the most powerful molecular outflows.
We also detect the OH 1.667 GHz maser line from both sources and demonstrate
its utility in detecting molecular outflows.Comment: 29 pages, 17 figures, 6 tables, accepted to Ap
A loss-of-function mutation in RORB disrupts saltatorial locomotion in rabbits
Saltatorial locomotion is a type of hopping gait that in mammals can be found in rabbits, hares, kangaroos, and some species of rodents. The molecular mechanisms that control and fine-tune the formation of this type of gait are unknown. Here, we take advantage of one strain of domesticated rabbits, the sauteur d'Alfort, that exhibits an abnormal locomotion behavior defined by the loss of the typical jumping that characterizes wild-type rabbits. Strikingly, individuals from this strain frequently adopt a bipedal gait using their front legs. Using a combination of experimental crosses and whole genome sequencing, we show that a single locus containing the RAR related orphan receptor B gene (RORB) explains the atypical gait of these rabbits. We found that a splice-site mutation in an evolutionary conserved site of RORB results in several aberrant transcript isoforms incorporating intronic sequence. This mutation leads to a drastic reduction of RORB-positive neurons in the spinal cord, as well as defects in differentiation of populations of spinal cord interneurons. Our results show that RORB function is required for the performance of saltatorial locomotion in rabbits.Author summaryRabbits and hares have a characteristic jumping gait composed of an alternate rhythmical movement of the forelimbs and a synchronous bilateral movement of the hindlimbs. We have now characterized a recessive mutation present in a specific strain of domestic rabbits (sauteur d'Alfort) that disrupts the jumping gait. The mutation causing this defect in locomotion pattern occurs in the gene coding for the transcription factor RORB that is normally expressed in many regions of the nervous system especially in the spinal cord dorsal horn. Our results show that expression of RORB is drastically reduced in the spinal cord of affected rabbits which results in a developmental defect. This study is an advance in our understanding how locomotion is controlled in vertebrates
MeerKLASS: MeerKAT Large Area Synoptic Survey
We discuss the ground-breaking science that will be possible with a wide area
survey, using the MeerKAT telescope, known as MeerKLASS (MeerKAT Large Area
Synoptic Survey). The current specifications of MeerKAT make it a great fit for
science applications that require large survey speeds but not necessarily high
angular resolutions. In particular, for cosmology, a large survey over for hours will potentially provide the first
ever measurements of the baryon acoustic oscillations using the 21cm intensity
mapping technique, with enough accuracy to impose constraints on the nature of
dark energy. The combination with multi-wavelength data will give unique
additional information, such as exquisite constraints on primordial
non-Gaussianity using the multi-tracer technique, as well as a better handle on
foregrounds and systematics. Such a wide survey with MeerKAT is also a great
match for HI galaxy studies, providing unrivalled statistics in the pre-SKA era
for galaxies resolved in the HI emission line beyond local structures at z >
0.01. It will also produce a large continuum galaxy sample down to a depth of
about 5\,Jy in L-band, which is quite unique over such large areas and
will allow studies of the large-scale structure of the Universe out to high
redshifts, complementing the galaxy HI survey to form a transformational
multi-wavelength approach to study galaxy dynamics and evolution. Finally, the
same survey will supply unique information for a range of other science
applications, including a large statistical investigation of galaxy clusters as
well as produce a rotation measure map across a huge swathe of the sky. The
MeerKLASS survey will be a crucial step on the road to using SKA1-MID for
cosmological applications and other commensal surveys, as described in the top
priority SKA key science projects (abridged).Comment: Larger version of the paper submitted to the Proceedings of Science,
"MeerKAT Science: On the Pathway to the SKA", Stellenbosch, 25-27 May 201
Genetic Homogeneity of Measles Viruses Associated with a Measles Outbreak, SĂŁo Paulo, Brazil, 1997
Control algorithms based on the active and non-active currents for a UPQC without series transformers
This study presents control algorithms for a new unified power quality conditioner (UPQC) without the series transformers that are frequently used to make the insertion of the series converter of the UPQC between the power supply and the load. The behaviour of the proposed UPQC is evaluated in presence of voltage imbalances, as well as under non-sinusoidal voltage-and current conditions. The presented algorithms derive from the concepts involving the active and non-active currents, together with a phase-locked-loop circuit. Based on these real-time algorithms, and considering the proposed hardware topology, the UPQC is able to compensate the harmonic components of the voltages and currents, correct the power factor, and keep the load voltages regulated, all of this in a dynamic way, responding instantaneously to changes in the loads or in the electrical power system. The control algorithms were distributed in a two-DSP digital control architecture, without any communication between them. Consequently, can be increased the sampling frequency of the acquired voltages and currents and improve the UPQC performance. Furthermore, some constraints of the proposed UPQC are evidenced, particularly when the main voltages are imbalanced. Simulation and experimental results are presented to verify the UPQC performance under transient and steady state conditions.info:eu-repo/semantics/publishedVersio
Understanding how birds rebuild fat stores during migration: insights from an experimental study
Publisher's version (Ăștgefin grein).Mechanisms underlying fat accumulation for long-distance migration are not fully understood. This
is especially relevant in the context of global change, as many migrants are dealing with changes in
natural habitats and associated food sources and energy stores. The continental Black-tailed godwit
Limosa limosa limosa is a long-distance migratory bird that has undergone a considerable dietary shift
over the past few decades. Historically, godwits fed on an animal-based diet, but currently, during the
non-breeding period godwits feed almost exclusively on rice seeds. The latter diet may allow building
up of their fuel stores for migration by signifcantly increasing de novo lipogenesis (DNL) activity. Here,
we performed an experiment to investigate lipid fux and the abundance of key enzymes involved in
DNL in godwits, during fasting and refueling periods at the staging site, while feeding on rice seeds or
fy larvae. Despite no signifcant diferences found in enzymatic abundance (FASN, ME1, ACC and LPL)
in stored fat, experimental godwits feeding on rice seeds presented high rates of DNL when compared
to fy-larvae fed birds (~35 times more) and fasted godwits (no DNL activity). The increase of fractional
DNL in godwits feeding on a carbohydrate-rich diet can potentially be enhanced by the fasting period
that stimulates lipogenesis. Although requiring further testing, these recent fndings provide new
insights into the mechanisms of avian fat accumulation during a fasting and refueling cycle and
associated responses to habitat and dietary changes in a migratory species.Te authors acknowledge fnancial support from FundacÌ§ĂŁo para a Ciencia e Tecnologia (FCT) in the form of
fellowships to PMA (SFRH/BD/69238/2010), IV (SFRH/BPD/90032/2012) and JAA (SFRH/BPD/91527/2012)
and research Project CGL2017-89009-P. NMR data were collected at the UC-NMR facility that is supported
by FEDER and FCT (RECI/QEQ-QFI/0168/2012, CENTRO-07-CT62-FEDER-002012) and Rede Nacional
de Ressonancia MagneÌtica Nuclear (RNRMN). Tis study benefted from funding by the strategic program of
MARE, fnanced by FCT (UID/MAR/04292/2019), and by FTC/MCTES to CESAM, (UID/AMB/50017 â POCI01-0145-FEDER-007638), through national funds.Peer Reviewe
Central-West Siberian-breeding Bar-tailed Godwits (<i>Limosa lapponica</i>) segregate in two morphologically distinct flyway populations
Long-distance migratory species often include multiple breeding populations, with distinct migration routes, wintering areas and annual-cycle timing. Detailed knowledge on population structure and migratory connectivity provides the basis for studies on the evolution of migration strategies and for species conservation. Currently, five subspecies of Bar-tailed Godwits Limosa lapponica have been described. However, with two apparently separate breeding and wintering areas, the taxonomic status of the subspecies L. l. taymyrensis remains unclear. Here we compare taymyrensis Bar-tailed Godwits wintering in the Middle East and West Africa, respectively, with respect to migration behaviour, breeding area, morphology and population genetic differentation in mitochondrial DNA. By tracking 52 individuals from wintering and staging areas over multiple years, we show that Bar-tailed Godwits wintering in the Middle East bred on the northern West-Siberian Plain (n = 19), while birds from West Africa bred further east, mostly on the Taimyr Peninsula (n = 12). The two groups differed significantly in body size and shape, and also in the timing of both northward and southward migrations. However, they were not genetically differentiated, indicating that the phenotypic (i.e. geographical, morphological and phenological) differences arose either very recently or without current reproductive isolation. We conclude that the taymyrensis taxon consists of two distinct populations with mostly non-overlapping flyways, which warrant treatment as separate taxonomic units. We propose to distinguish a more narrowly defined taymyrensis subspecies (i.e. the Bar-tailed Godwits wintering in West Africa and breeding on Taimyr), from a new subspecies (i.e. the birds wintering in the Middle East and breeding on the northern West-Siberian Plain)
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