Abstract
We modeled the geometry and the three-dimensional orientation of the ejecta cone triggered by the impact of the DART spacecraft on the asteroid Dimorphos. We used eight LUKE images of the ...impact acquired by the CubeSat LICIACube that flew by the Didymos system shortly after the impact. These images, which show the ejecta cone in both face-on and side-on profiles, enabled us to reconstruct the ejecta cone in inertial space. We started our model as a simple cone with a circular base and developed it to a rotated cone with an elliptical base that best fit the data. The cone axis points to R.A., decl. (in J2000):
147
−
10
°
+
1
°
, +
16
−
6
°
+
4
°
. The cone is characterized by two perpendicular half-angles of
η
=
69
−
3
°
+
1
°
,
γ
=
51
−
11
°
+
1
°
and a rotation of
ω
= 12° around its axis. The apex of the cone is located near the center of Dimorphos within 15 m. The intersection of the cone and the surface of Dimorphos (surface enclosed by the cone) would correspond to a crater with a maximum radius of about 65 m. The characterization of the cone axis is directly related to the computation of the momentum enhancement factor (
β
) of the impact, and it hence proves the crucial need of studying impacts in the context of planetary defence scenarios. The results of this work could potentially be used to constrain whether the impact took place in a strength-dominated or a gravity-dominated regime. This work shows the important scientific return of the LICIACube CubeSat in the context of planetary defence.
We investigate the synchronization features of a network of spiking neurons under a distance-dependent coupling following a power-law model. The interplay between topology and coupling strength leads ...to the existence of different spatiotemporal patterns, corresponding to either nonsynchronized or phase-synchronized states. Particularly interesting is what we call synchronization malleability, in which the system depicts significantly different phase-synchronization degrees for the same parameters as a consequence of a different ordering of neural inputs. We analyze the functional connectivity of the network by calculating the mutual information between neuronal spike trains, allowing us to characterize the structures of synchronization in the network. We show that these structures are dependent on the ordering of the inputs for the parameter regions where the network presents synchronization malleability and we suggest that this is due to a complex interplay between coupling, connection architecture, and individual neural inputs.
We report the preparation of rhodium nanoparticles (NPs) stabilized by 1-octadecanethiol (ODT), polyvinyl alcohol (PVA), and tetraoctylammonium bromide (TOAB), and their application for hydrogenation ...catalysis. The three metal–ligand systems correspond to different mechanism of NPs stabilization via strong covalent linkage, chemisorbed atoms and electrostatic interactions, respectively. We found a strong effect of the interaction between the stabilizer and the surface of the metal nanoparticle on the catalytic activity. The Rh NPs were studied as soluble nanoparticle catalysts and as precursors for the synthesis of supported catalysts. All catalysts were tested in the hydrogenation of cyclohexene under similar conditions as a model reaction. Generally, Rh
–
ODT NPs were inactive, Rh
–
PVA NPs exhibited distinct activities in solution (aqueous biphasic catalysis) and as a supported catalyst, and Rh
–
TOAB NPs exhibited similar activities in solution and after immobilization. This last result opens the opportunity for the preparation of highly active Rh NP catalysts both in solution and as a heterogeneous catalyst. Additionally, the stability of the nanoparticles depends on the choice of ligand and on the functionalization of the support surface before immobilization. By optimizing the catalyst synthesis and reaction conditions, turnover frequencies as high as 700,000 h
−1
where observed for stable and recyclable catalyst.
Abstract The NASA Double Asteroid Redirection Test (DART) spacecraft impacted the moon Dimorphos of the 65803 Didymos binary system and changed the binary orbit period, demonstrating asteroid ...deflection by a kinetic impact and indicating that more momentum was transferred to Dimorphos by escaping impact ejecta than was incident with DART. Images of the DART impact ejecta plume were obtained by the Light Italian cubesat for Imaging of Asteroids (LICIACube) in the first few minutes after the DART impact. The ejecta plume imaged by LICIACube 158 s after the DART impact prior to closest approach shows no evidence for plume clearing at low altitude. The ejecta plume imaged 175 s after the DART impact is optically thick up to projected altitudes of 200 m above the surface of Dimorphos. These observations are compared with models of the impact ejecta plume optical depth, structure, and evolution, which are developed from point-source scaling models fitted to numerical simulations of the DART impact into a rubble pile Dimorphos with different material strengths. The observations of the impact plume optical depth and the high momentum transfer from the DART impact are not consistent with impact and ejecta plume models assuming the Dimorphos cohesive strength to be as high as 5000 Pa. Models with 5 and 50 Pa Dimorphos cohesive strength provide the overall best consistency with plume opacity observations and high momentum transfer.
BACKGROUNDAttending rounds at academic medical centers are often disconnected from patients and team members who are not physicians. Regionalization of care teams may facilitate bedside rounding and ...more frequent interactions among doctors, nurses, and patients.OBJECTIVEWe used time-motion analysis to investigate how regionalization of medical teams and encouragement of bedside rounds affect participants on rounds and rounding time.DESIGN AND SETTINGWe used pre-post analysis to study the effects of care redesign on teams' daily rounds on a general medicine service at an academic medical center.PARTICIPANTSFour general medical teams were evaluated before the intervention and 5 teams afterward.INTERVENTIONSGeneral medical teams were regionalized to specific units, the admitting structure was changed to facilitate regionalization, and teams were encouraged to round bedside.MEASUREMENTSPrimary outcomes included proportion of time each team member was present on rounds and proportion of bedside rounding time. Secondary outcomes included round duration and non-patient time during rounds.RESULTSProportion of time the nurse was present on rounds increased from 24.1% to 67.8% (P ⟨ 0.001), and proportion of total bedside rounding time increased from 39.9% to 55.8% (P ⟨ 0.001). Mean total rounding time decreased from 3.0 hours to 2.4 hours (P = 0.01), despite a higher patient census.CONCLUSIONSCreating regionalized care teams and encouraging interdisciplinary bedside rounds increased the proportion of bedside rounding time and the presence of nurses on rounds while decreasing total rounding time. Journal of Hospital Medicine 2017;12:150-156.
AbstractThe objective of this study was to verify the effects of ethanol consumption and alcohol detoxification on the biomechanics, area and thickness of cortical and trabecular bone in rat femur. ...This was an experimental study in which 18 male Wistar rats were used, with 40 days of age, weighing 179±2.5 g. The rats were divided into three groups (n=06): CT (control), AC (chronic alcoholic), DT (detoxification). After experimental procedures, the animals were euthanized by an overdose of the anesthetic and their femurs were collected for mechanical testing and histological processing. All animals did not present malnutrition or dehydration during experimentation period. Morphometric analysis of cortical and trabecular bones in rat femurs demonstrated that AC animals showed inferior dimensions and alcohol detoxification (DT) allowed an enhancement in area and thickness of cortical and trabecular bone. Material and structural properties data of AC group highlighted the harmful effects of ethanol on bone mechanical properties. The results of this study demonstrated that chronic alcoholic rats (AC) presented major bone damage in all analyzed variables. Those findings suggested that alcohol detoxification is highly suggested in pre-operative planning and this corroborates to the success of bone surgery and bone tissue repair. Thanks to the financial support offered by PROBIC - UNIFENAS.
Forest fragmentation reduces the effective size of natural populations, isolates individuals in the landscape, and, consequently, changes species' mating systems by increasing the degree of ...relatedness between individuals and inbreeding. Investigating the impact of habitat degradation on forest fragments helps to assess the genetic and ecological consequences of these changes, and allows the development of effective and sustainable conservation strategies to manage the genetic resources of species living in degraded landscapes. The aim of the present study was to assess the genetic diversity of fragmented Theobroma speciosum populations using microsatellite markers. Three urban forest fragments were selected in the municipality of Alta Floresta, Mato Grosso State, Brazil, namely C/E park, J park, and Zoo Botanical park. Seventy-five individuals (25 in each fragment) were sampled by collecting their leaves for genomic DNA extraction. Polymerase chain reaction amplifications were performed using nine polymorphic simple sequence repeat primers, which amplified 84 alleles. The mean expected heterozygosity was 0.970, and it was always higher than the observed heterozygosity. Analysis of molecular variance revealed that most variability occurred within populations (64%) rather than between them (36%). The Structure software and an unweighted pair group method with arithmetic mean dendrogram revealed three distinct groups, showing that individuals were allocated to their correct populations. Genotype number 3 from C/E park, number 45 from J park, and number 51 from Zoo Botanical park could be used as stock plants in breeding programs, because they were the most dissimilar within the populations studied. The high genetic diversity levels detected in all three populations studied emphasize the importance of protecting this species in its natural habitat.
A botanical survey of 24 commercial dairy pastures ranging in post-sowing age and perennial ryegrass type (mid-season diploid, late-season diploid, tetraploid) was undertaken in each of Waikato-Bay ...of Plenty (BoP), Taranaki and Canterbury during autumn/winter. The mean perennial ryegrass proportion (85% of total DM) and tiller density (3252 m ⁻²) was greatest in Canterbury and the broadleaved weed proportion lowest (2%). Conversely, Waikato–BoP had the lowest ryegrass proportion (59%), tiller density (1817 m ⁻²) and greatest proportion of broadleaved weeds (15%), with Taranaki intermediate. Tiller density was greater in pastures sown with diploid rather than tetraploids (averaging 3033 vs. 1784 m ⁻²). Grass grub (Costelytra zealandica , 11 m ⁻²) populations were lowest in the youngest age category pastures where nematode populations were highest (80 g ⁻¹ dry soil). The soil seedbank was dominated by unsown species (with total species emergence averaging 4594 seeds m ⁻²), with negligible ryegrass emergence.
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