1,051 research outputs found
Starburst galaxies in the COSMOS field : clumpy star-formation at redshift 0 < z <0.5
This work has been funded by the Spanish MINECO, Grant ESTALLIDOS, AYA2013-47742-C4-2P and AYA2010-21887-C04-04. J.M.A. acknowledges support from the European Research Council Starting Grant SEDMorph (P.I. V. Wild). R.H.G. acknowledges the FPI grant from MINECO within ESTALLIDOS project.Context. At high redshift, starburst galaxies present irregular morphologies with 10-20% of their star formation occurring in giant clumps. These clumpy galaxies are considered the progenitors of local disk galaxies. To understand the properties of starbursts at intermediate and low redshift, it is fundamental to track their evolution and the possible link with the systems at higher z. Aims. We present an extensive, systematic, and multiband search and analysis of the starburst galaxies at redshift (0 1010. We classify galaxies into three main types, depending on their HST morphology: single knot (Sknot), single star-forming knot plus diffuse light (Sknot+diffuse), and multiple star-forming knots (Mknots/clumpy) galaxy. We found a fraction of Mknots/clumpy galaxy fclumpy = 0.24 considering out total sample of starburst galaxies up to z ⌠0.5. The individual star-forming knots in our sample follows the same L(Hα) vs. size scaling relation as local giant HII regions. However, they slightly differ from the one provided using samples at high redshift. This result highlights the importance of spatially resolving the star-forming regions for this kind of study. Star-forming clumps in the central regions of Mknots galaxies are more massive, and present higher star formation rates, than those in the outskirts. This trend is less clear when we consider either the mass surface density or surface star formation rate. Sknot galaxies do show properties similar to both dwarf elliptical and irregulars in the surface brightness (Ό) versus Mhost diagram in the B-band, and to spheroidals and ellipticals in the Ό versus Mhost diagram in the V-band. Conclusions. The properties of our star-forming knots in Sknot+diffuse and Mknots/clumpy galaxies support the predictions of recent numerical simulations claiming that they have been produced by violent disk instabilities. We suggest that the evolution of these knots means that large and massive clumps at the galaxy centers represent the end product of the coalescence of surviving smaller clumps from the outskirts. Our results support this mechanism and make it unlikely that mergers are the reason behind the observed starburst knots. Sknot galaxies might be transitional phases of the Blue Compact Dwarfs (BCD) class, with their properties consistent with spheroidal-like, but blue structures.Publisher PDFPeer reviewe
A Contribution to the Knowledge of the Ochid Bes of the Los Amigos Biological Station, Peru (Hymenoptera, Apidae, Euglossini) [Abstract]
The effect of sinoaortic denervation on renal wrap hypertension
The purpose of this study was to determine whether sinoaortic deafferentation (SAD) alters the severity of hypertension or sympathoadrenal contribution to mean blood pressure (MAP) during renal wrap hypertension. Male Sprague-Dawley rats were implanted with radiotelemetry transmitters for 24-hour recording of MAP and heart rate. All rats underwent either SAD or sham SAD (Intact) surgery and were allowed to recover for 10 to 14 days. The rats were then assigned to a normotensive (Sham) group or a hypertensive (Wrap) group in which 1-kidney figure-8 renal wrap was performed. SAD increased the acute MAP response to renal wrap (Intact-Sham=5+/-1 mm Hg, Intact-Wrap=45+/-3 mm Hg, SAD-Sham=3+/-3 mm Hg, SAD-Wrap=58+/-4 mm Hg) and increased the lability of MAP (SD of MAP; Intact-Sham=3.8+/-0.2, Intact-Wrap=4.2+/-0.3, SAD-Sham=9. 6+/-1.4, SAD-Wrap=9.7+/-1.4). MAP was not different between SAD and Intact rats during 4 weeks after renal wrap or sham surgery; however, induction of hypertension produced additional MAP variability that was independent of SAD (Intact-Sham=4.6+/-0.4, Intact-Wrap=6.2+/-0.6, SAD-Sham=6.3+/-0.5, SAD-Wrap=10.8+/-1.5). In a separate group of rats, the sympathoadrenal contribution to MAP was assessed by the depressor response to ganglionic blockade and plasma norepinephrine at rest and after neuronal uptake inhibition with desipramine. The depressor response to ganglionic blockade was significantly increased by renal wrap and by SAD (Intact-Sham=-49+/-2 mm Hg, Intact-Wrap=-73+/-4 mm Hg, SAD-Sham=-77+/-5 mm Hg, SAD-Wrap=-96+/-6 mm Hg). In the 3 groups with enhanced ganglionic blockade responses, desipramine caused a significant increase in plasma norepinephrine. These results indicate that SAD does not alter the development of renal wrap hypertension but does increase the sympathoadrenal contribution to MAP in both normotensive and hypertensive animal
A wot-based method for creating digital sentinel twins of iot devices
The data produced by sensors of IoT devices are becoming keystones for organizations to conduct critical decision-making processes. However, delivering information to these processes in real-time represents two challenges for the organizations: the first one is achieving a constant dataflow from IoT to the cloud and the second one is enabling decision-making processes to retrieve data from dataflows in real-time. This paper presents a cloud-based Web of Things method for creating digital twins of IoT devices (named sentinels).The novelty of the proposed approach is that sentinels create an abstract window for decision-making processes to: (a) find data (e.g., properties, events, and data from sensors of IoT devices) or (b) invoke functions (e.g., actions and tasks) from physical devices (PD), as well as from virtual devices (VD). In this approach, the applications and services of decision-making processes deal with sentinels instead of managing complex details associated with the PDs, VDs, and cloud computing infrastructures. A prototype based on the proposed method was implemented to conduct a case study based on a blockchain system for verifying contract violation in sensors used in product transportation logistics. The evaluation showed the effectiveness of sentinels enabling organizations to attain data from IoT sensors and the dataflows used by decision-making processes to convert these data into useful information
Impact of using an evidence-based clinical guideline for the management of primary vesicoureteral reflux in children
Objective: To analyze changes in the therapeutic approach at a tertiary care hospital following the implementation of a clinical guideline for the treatment of primary vesicoureteral reflux (VUR) in children. Population and methods: Retrospective study conducted in a cohort of patients with primary VUR (1989-2015) aged 0-15 years at a tertiary care hospital. The therapeutic approach before and after the development of the clinical guideline (2008) was compared. Results: A total of 297 patients (49.8% boys, 50.2% girls) were included; their mean age at the time of diagnosis was 21.71 months. VUR grading was: VUR I-III 45.1%, VUR IV-V 54, 9%; 124 were treated after the implementation of the clinical guideline (group 1), and 173, before (group 2). The mean follow-up period was 124.32 months. A conservative approach was the initial treatment in 70.3% of group 1 patients and 67.9% of group 2 patients. The number of surgeries remains constant (31.45% versus 31.79%), with an increase in the number of endoscopic surgeries (p< 0.005). The profile of patients has changed based on the application of the algorithm proposed by the guideline. Fewer surgeries were done in patients with VUR IV-V (82.32% versus 59.9%, p= 0.000) and there were fewer cases of kidney damage at diagnosis (49.4% versus 9.8%, p= 0.000). Conclusions: The implementation of the clinical guideline has favored an initially conservative approach in patients with severe grade VUR and nephropathy, for whom surgery was traditionally indicated initially. Using clinical guidelines favors a unanimous, evidence-based approach that reduces the performance of unnecessary invasive procedures
The Green Bank Northern Celestial Cap Pulsar Survey - I: Survey Description, Data Analysis, and Initial Results
We describe an ongoing search for pulsars and dispersed pulses of radio
emission, such as those from rotating radio transients (RRATs) and fast radio
bursts (FRBs), at 350 MHz using the Green Bank Telescope. With the Green Bank
Ultimate Pulsar Processing Instrument, we record 100 MHz of bandwidth divided
into 4,096 channels every 81.92 . This survey will cover the entire sky
visible to the Green Bank Telescope (, or 82% of the sky)
and outside of the Galactic Plane will be sensitive enough to detect slow
pulsars and low dispersion measure (30 ) millisecond
pulsars (MSPs) with a 0.08 duty cycle down to 1.1 mJy. For pulsars with a
spectral index of 1.6, we will be 2.5 times more sensitive than previous and
ongoing surveys over much of our survey region. Here we describe the survey,
the data analysis pipeline, initial discovery parameters for 62 pulsars, and
timing solutions for 5 new pulsars. PSR J02145222 is an MSP in a long-period
(512 days) orbit and has an optical counterpart identified in archival data.
PSR J06365129 is an MSP in a very short-period (96 minutes) orbit with a
very low mass companion (8 ). PSR J06455158 is an isolated MSP
with a timing residual RMS of 500 ns and has been added to pulsar timing array
experiments. PSR J14347257 is an isolated, intermediate-period pulsar that
has been partially recycled. PSR J18164510 is an eclipsing MSP in a
short-period orbit (8.7 hours) and may have recently completed its spin-up
phase.Comment: 18 pages, 10 figures, 5 tables, accepted by Ap
The Green Bank North Celestial Cap Pulsar Survey. IV: Four New Timing Solutions
We present timing solutions for four pulsars discovered in the Green Bank
Northern Celestial Cap (GBNCC) survey. All four pulsars are isolated with spin
periods between 0.26s and 1.84s. PSR J00382501 has a 0.26s
period and a period derivative of ,
which is unusually low for isolated pulsars with similar periods. This low
period derivative may be simply an extreme value for an isolated pulsar or it
could indicate an unusual evolution path for PSR J00382501, such as a
disrupted recycled pulsar (DRP) from a binary system or an orphaned central
compact object (CCO). Correcting the observed spin-down rate for the Shklovskii
effect suggests that this pulsar may have an unusually low space velocity,
which is consistent with expectations for DRPs. There is no X-ray emission
detected from PSR J00382501 in an archival swift observation, which suggests
that it is not a young orphaned CCO. The high dispersion measure of PSR
J1949+3426 suggests a distance of 12.3kpc. This distance indicates that PSR
J1949+3426 is among the most distant 7% of Galactic field pulsars, and is one
of the most luminous pulsars.Comment: 7 pages, 5 figure
Autonomous Operation of a Reconfigurable Multi-Robot System for Planetary Space Missions
Reconfigurable robots can physically merge and form new types of composite systems. This ability leads to additional degrees of freedom for robot operations especially when dynamically composed robotic systems offer capabilities that none of the individual systems have. Research in the area of reconfigurable multi-robot systems has mainly been focused on swarm-based robots and thereby to systems with a high degree of modularity but a heavily restricted set of capabilities. In contrast, this thesis deals with heterogeneous robot teams comprising individually capable robots which are also modular and reconfigurable. In particular, the autonomous application of such reconfigurable multi-robot systems to enhance robotic space exploration missions is investigated. Exploiting the flexibility of a reconfigurable multi-robot system requires an appropriate system model and reasoner. Hence, this thesis introduces a special organisation model. This model accounts for the key characteristics of reconfigurable robots which are constrained by the availability and compatibility of hardware interfaces. A newly introduced mapping function between resource structures and functional properties permits to characterise dynamically created agent compositions. Since a combinatorial challenge lies in the identification of feasible and functionally suitable agents, this thesis further suggests bounding strategies to reason efficiently with composite robotic systems. This thesis proposes a mission planning algorithm which permits to exploit the flexibility of reconfigurable multi-robot systems. The implemented planner builds upon the developed organisation model so that multi-robot missions can be specified by high-level functionality constraints which are resolved to suitable combinations of robots. Furthermore, the planner synchronises robot activities over time and characterises plans according to three objectives: efficacy, efficiency and safety. The plannera s evaluation demonstrates an optimization of an exemplary space mission. This research is based on the parallel development of theoretical concepts and practical solutions while working with three reconfigurable multi-robot teams. The operation of a reconfigurable robotic team comes with practical constraints. Therefore, this thesis composes and evaluates an operational infrastructure which can serve as reference implementation. The identification and combination of applicable state-of-the-art technologies result in a distributed and dynamically extensible communication infrastructure which can maintain the properties of reconfigurable multi-robot systems. Field tests covering semi-autonomous and autonomous operation have been performed to characterise multi-robot missions and validate the autonomous control approach for reconfigurable multi-robot systems. The practical evaluation identified critical constraints and design elements for a successful application of reconfigurable multi-robot systems. Furthermore, the experiments point to improvements for the organisation model. This thesis is a wholistic approach to automate reconfigurable multi-robot systems. It identifies theoretical as well as practical challenges and it suggests effective solutions which permit an exploitation of an increased level of flexibility in future robotics missions
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