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North African knapweed (Centaurea diluta Aiton) is an annual weed that is widespread in southern Spain and is of increasing concern in dryland cropping systems. Despite its expanding range in Spain, there is limited information on the emergence timing and pattern of this species, which is critical for developing more timely and effective management strategies. Therefore, there is a need to develop simple and reliable models to predict the timing and emergence of this annual weed under dryland conditions. A multi-location field experiment was established across Spain in 2016-2017 to assess the emergence of C. diluta. At each of 11 locations, seeds were sown in the fall, and emergence was recorded. Overall emergence averaged 39% in the first year across all sites and 11% in the second year. In both years, the main emergence flush occurred at beginning of the growing season. The three-parameter Weibull function best described seedling emergence of C. diluta. Emergence models were developed based on thermal time (TT) and hydrothermal time (HTT) and showed high predictability, as evidenced by root mean square error prediction (RMSEP) values of 10.8 and 10.7, respectively. The three cardinal points were established for TT and HHT at 0.5 ºC, 10 ºC and 35 ºC for base, optimal and ceiling temperature, while base water potential was estimated at -0.5MPa.
Regeneration from seed affects species assembly in plant communities, and temperature is the most important environmental factor controlling the germination process. Thermal dependence of seed germination is thus associated with species occurrence in an ecosystem. Hence, we aimed to investigate the role of temperature on seed germination of ten tree species from the western Brazilian Amazon. Seeds were collected in the state of Rondônia, Brazil, and set to germinate under constant temperatures ranging from 10 to 40°C in germination chambers. We calculated germination capacity (G%), germination rate (GR50, reciprocal of germination time), and thermal parameters, such as cardinal temperatures and thermal time requirements. Most species had a large range of temperatures showing G% ≥80%, with optimal temperature varying from 20 to 40°C. Base temperature ranged from 6 to 12°C and ceiling temperatures were mainly >40°C. Astronium lecointei and Parkia nitida showed high germination capacity under temperatures of 35–40°C, while germination of Theobroma cacao dropped from 100% to zero under temperatures between 37 and 40°C. The climax species Cedrela fissilis had the slowest germination time (10 days) and highest thermal time requirement, while seeds of Enterolobium schomburgkii (a late-successional species) germinated within the first day of the experiment. Rapid recruitment of Amazon species could be favoured with treefall disturbance, which increases temperatures in the understory, but sharp limits might be found in the supra-optimal range of temperatures. Such patterns might indicate different regeneration strategies in the tropical rainforest, providing important information regarding seed germination among Amazon species.
Attractive colloidal dispersions, suspensions of fine particles which aggregate and frequently form a space-spanning elastic gel are ubiquitous materials in society with a wide range of applications. The colloidal networks in these materials can exist in a mode of free settling when the network weight exceeds its compressive yield stress. An equivalent state occurs when the network is held fixed in place and used as a filter through which the suspending fluid is pumped. In either scenario, hydrodynamic instabilities leading to loss of network integrity occur. Experimental observations have shown that the loss of integrity is associated with the formation of eroded channels, so-called streamers, through which the fluid flows rapidly. However, the dynamics of growth and subsequent mechanism of collapse remain poorly understood. Here, a phenomenological model is presented that describes dynamically the radial growth of a streamer due to erosion of the network by rapid fluid back flow. The model exhibits a finite-time blowup – the onset of catastrophic failure in the gel – due to activated breaking of the inter-colloid bonds. Brownian dynamics simulations of hydrodynamically interacting and settling colloids in dilute gels are employed to examine the initiation and propagation of this instability, which are in good agreement with the theory. The model dynamics is also shown to accurately replicate measurements of streamer growth in two different experimental systems. The predictive capabilities and future improvements of the model are discussed and a stability-state diagram is presented providing insight into engineering strategies for avoiding settling instabilities in networks meant to have long shelf lives.
Our aim is to present a new and so far most complete catalog of optically selected young stars. The basis of this work is an extensive literature search for young stars in all the known nearby (< 2 kpc) star forming regions, included in the Handbook of Star Forming Regions [4, 5], and in 67 additional catalogs. We collected data on known young, pre-main-sequence stars detected in optical bands. The catalog contains the celestial coordinates, object names, names of the enclosing star forming region, identification methods, distances, and other information (e.g., references, binarity) for 15208 young stellar objects. It is already in use by the Gaia Photometric Science Alerts Team to identify variable young stars in the Gaia data. Our catalog was cross-correlated with the Gaia DR2 and we obtained flux and distance estimations for 86% of the stars.
We present our results from a mid-infrared interferometric survey targeted at the planet-forming region in the circumstellar disks around low- and intermediate-mass young stars. Our sample consists of 82 objects, including T Tauri stars, Herbig Ae stars, and young eruptive stars. Our main results are: 1) Disks around T Tauri stars are similar to those around Herbig Ae stars, but are relatively more extended once we account for stellar luminosity. 2) From the distribution of the sizes of the mid-infrared emitting region we find that inner dusty disk holes may be present in roughly half of the sample. 3) Our analysis of the silicate spectral feature reveals that the dust in the inner ~1 au region of disks is generally more processed than that in the outer regions. 4) The dust in the disks of T Tauri stars typically show weaker silicate emission in the N band spectrum, compared to Herbig Ae stars, which may indicate a general difference in the disk structure. Our data products are available at VizieR, and at the following web page: http://konkoly.hu/MIDI_atlas.
The objectives of the current study were to investigate the dynamics of body calcium (Ca) and to estimate the net Ca maintenance requirements (NCam) of Saanen goats, using 45Ca as a radiotracer. Eighteen castrated male Saanen goats (25 ± 2.3 kg body weight (BW)) received a basal diet (ground ear maize, ground maize and vitamin–mineral premix). The treatments consisted of adding limestone to the basal diet to provide Ca content of 0.6, 1.7 and 3.0 g/kg dry matter (DM). The experiment lasted 45 days (i.e. 36 d of adaptation and 9 days of measurements). On day 38, 0.5 ml of 7.4 MBq 45Ca solution was administrated before feeding. From days 39 to 45, samples of faeces, blood and urine were collected, and Ca concentration determined. The Ca intake, Ca in faeces, Ca in urine, faecal endogenous Ca and true absorbed Ca increased linearly as Ca content in the diets increased, while retained Ca increased at a decreasing rate. Dry matter intake decreased at an increasing rate with increased Ca content in the diets. In contrast, Ca content in the diets did not affect biological availability of Ca, or Ca in plasma. The true biological availability of Ca from limestone in Saanen goats was 0.72. The daily NCam was 11.6 (±1.3) mg/kg BW. The current results might help to understand Ca dynamics in goats and enhance the formulation of balanced diets to best meet Ca requirements of Saanen goats.
We conducted a matched-cohort study to assess mortality in schizophrenia and the relationship of mortality with comorbid somatic conditions and suicide attempts.
A full-population register-based prospective matched-cohort study was performed including all eligible patients with schizophrenia in Hungary between 01/01/2005 and 31/12/2013. Control subjects were individually matched to patients with schizophrenia at a 5:1 ratio. The principal outcome measure was death due to any reason. A non-parametric approach was used for descriptive statistical purposes, the Kaplan-Meier model for survival analysis, and the Cox proportional-hazards regression model for inferential statistics.
Patients with schizophrenia (n = 65,169) had substantially higher risk of all-cause mortality than the control subjects (n = 325,435) (RR = 2.4; P < 0.0001). Comorbidities and suicide attempts were associated with significantly increased mortality in both groups. As compared to the controls, 20-year old males with schizophrenia had a shorter life expectancy by 11.5 years, and females by 13.7 years; the analogous numbers for 45-year old schizophrenics were 8.1 and 9.6 years, respectively.
A significant mortality gap – mainly associated with somatic comorbidities – was detected between patients with schizophrenia and individually matched controls. Improved medical training to address the disparity in mortality, and many other factors including lack of resources, access to and model of medical care, lifestyle, medication side effects, smoking, stigma, need for early intervention and adequate health care organization could help to better address the physical health needs of patients with schizophrenia.
To determine the effects of lipid-based nutrient supplements (LNS) on children’s Hb, linear growth and development, compared with supplementation with micronutrient powder (MNP).
The study was a two-arm parallel-group randomized controlled trial, where participants received either LNS or MNP for daily consumption during 6 months. Supplements were delivered by staff at government-run health centres. Hb, anthropometric, motor development, language development and problem-solving indicators were measured by trained research assistants when children were 12 months of age.
The study was conducted in five rural districts in the Province of Ambo in the Department of Huánuco, Peru.
We enrolled 6-month-old children (n 422) at nineteen health centres.
Children who received LNS had a higher mean Hb concentration and lower odds of anaemia than those who received MNP. No significant differences in height-for-age, weight-for-height or weight-for-age Z-score, or stunting and underweight prevalence, were observed. Provision of LNS was associated with a higher pre-verbal language (gestures) score, but such effect lost significance after adjustment for covariates. Children in the LNS group had higher problem-solving task scores and increased odds of achieving this cognitive task than children in the MNP group. No significant differences were observed on receptive language or gross motor development.
LNS between 6 and 12 months of age increased Hb concentration, reduced anaemia and improved cognitive development in children, but showed no effects on anthropometric indicators, motor or language development.
Methiozolin is an isoxazoline herbicide being investigated for selective POST annual bluegrass control in managed turfgrass. Research was conducted to evaluate methiozolin efficacy for controlling two annual bluegrass phenotypes with target-site resistance to photosystem II (PSII) or enolpyruvylshikimate-3-phosphate synthase (EPSPS)-inhibiting herbicides (i.e., glyphosate), as well as phenotypes with multiple resistance to microtubule and EPSPS or PSII and acetolactate synthase (ALS)-inhibiting herbicides. All resistant phenotypes were established in glasshouse culture along with a known herbicide-susceptible control and treated with methiozolin at 0, 125, 250, 500, 1000, 2000, 4000, or 8000 g ai ha−1. Methiozolin effectively controlled annual bluegrass with target-site resistance to inhibitors of EPSPS, PSII, as well as multiple resistance to EPSPS and microtubule inhibitors. Methiozolin rates required to reduce aboveground biomass of these resistant phenotypes 50% (GR50 values) were not significantly different from the susceptible control, ranging from 159 to 421 g ha−1. A phenotype with target-site resistance to PSII and ALS inhibitors was less sensitive to methiozolin (GR50=862 g ha−1) than a susceptible phenotype (GR50=423 g ha−1). Our findings indicate that methiozolin is an effective option for controlling select annual bluegrass phenotypes with target-site resistance to several herbicides.
Based on the nature of the links and interactions existing at the hybrid interface, hybrid materials can be broadly classified in two main designations: a) Hybrid compounds Class I, that include all systems with electrostatic forces, hydrogen bonding or Van der Waals interactions and b) Hybrid compounds Class II, showing that the inorganic and organic components are linked through strong covalent or ionic-covalent bonds. The physico–chemical properties of nanostructured copolymer acrylates based on butyl acrylate (BA), methyl methacrylate (MMA) and acrylic acid (AA) has been investigated employing un-modified SiO2 (Class I) and modified SiO2 particles (Class II) using 3-(trimethoxysilyl) propyl methacrylate (MPS) as compatibilizing agent. The synthesis was carried out using seeded batch emulsion polymerization system. Metastable nanostructured emulsions containing 1 wt% nanoparticles were obtained. Films casted from the in-situ nanostructured latex exhibited excellent optical transparency suggesting good nanoparticles dispersion. However, the mechanical properties showed by SiO2-MPS nanocomposite, are better than the Class I hybrid compounds. Therefore, SiO2-MPS surface treatment prior to polymerization enhances the physical properties of copolymer BA-MMA-AA film. The mass loss derivative traces for the polyacrylic nanocomposites and the neat polymer obtained by thermogravimetric analysis showed that the onset temperature for thermal decomposition was shifted towards a higher temperature than the neat polyacrylic, indicating the enhancement of thermal stability of the un-modified SiO2 nanocomposite. However, there is a decrease of 40°C in the decomposition temperature for the modified polyacrylic nanocomposite. The results obtained so far have shown that weak Van der Waals and H-bonding interactions may be sufficient to enable improvement of the physical properties of the acrylate nanocomposites.
The field of composites materials has evolved from the use of traditional fillers (e.g. carbon and glass fibers) to nanoscale fillers that add unique and often multifunctional properties to the neat polymer. Because nanoparticles have extremely high surface to volume ratios, that alter the mobility of polymer chains near their interfaces, even a small addition of nanoparticles. These components have the potential to drastically transform the properties of the host polymers. While the last decade has observed several advances in the field of nanocomposites, some recent reviews have made it clear that definitive structure-property relationships are insufficient in the literature. The influence of inorganic TiO2 nanoparticles on the dynamic mechanical properties and microstructure of copolymer based on Butyl acrylate - Methyl methacrylate - Acrylic Acid has been investigated. The mechanical relaxations of the reinforced copolymer/TiO2 composites were studied under tension mode. Addition of TiO2 nanoparticles to acrylic copolymer produced a decrease in the glass transition temperature. Dynamic mechanical analysis (DMA) showed that the local motions associated with the alpha-transition (40°C) are enhanced as the frequency of oscillation increases, i.e. the tan d maximum increases at higher frequencies. The addition of TiO2 nanoparticles reduces significantly the strength of the alpha-transition. Thus, the cooperative molecular motions involving segments of the molecular chains associated with the alpha-transition were compromised by the presence of TiO2 nanoparticles resulting in a decrement of the storage modulus.
Clinical manifestations of acute bronchiolitis (AB) vary from minimal disease to severe respiratory failure. The response to respiratory viral infections is possibly influenced by genetic polymorphisms linked to the regulation of the inflammatory response. In the present study, we investigated whether interleukin-8 (IL-8) and interleukin-17 (IL-17) genetic variants are associated with the severity of AB. A group of Brazilian infants hospitalized with AB and a control group (infants with no or mild AB, without hospitalization) were genotyped for four IL-8/IL-17 variations. For replication, we studied an Argentinean population sample of infants with mild and severe AB. IL-8 polymorphism (rs 2227543) and IL-17 (rs2275913) variants showed significant associations with the severity of AB. The effect of the IL-8 variation could be replicated in the Argentinean sample. This finding suggests that IL-8 variations may influence the severity of AB in young infants. Further genetic association studies in low- or middle-income populations are necessary with the aim of expanding knowledge in this area.
While several scenarios have been proposed to explain supra-arcade downflows (SADs) observed descending through turbulent hot regions, none of them have systematically addressed the consideration of thermal conduction. The SADs are known to be voided cavities. Our model assumes that SADs are triggered by bursty localized reconnection events that produce non-linear waves generating the voided cavity. These subdense cavities are sustained in time because they are hotter than their surrounding medium. Due to the low density and large temperature values of the plasma we expect the thermal conduction to be an important process. Our main aim here is to study if it is possible to generate SADs in the framework of our model considering thermal conduction. We carry on 2D MHD simulations including anisotropic thermal conduction, and find that if the magnetic lines envelope the cavities, they can be isolated from the hot environment and be identified as SADs.
The study of the small magnetic structures of the solar photosphere is of great relevance because of their association with concentrations of magnetic field and their possible contribution to the variations of the Total Solar Irradiance. These structures are known to appear close to active regions and ubiquitously in the quiet Sun areas. Numerous studies about their distribution across all over the solar surface have been done with high-resolution instrumentation. However, since the observations have always been carried out from the ecliptic plane, their distribution near the polar regions is not well known. Future missions, like Solar Orbiter, will certainly provide valuable information on these yet unexplored regions. In this work, and in preparation for that moment, we select favorable periods for the observation of the polar regions of the Sun, and study the fraction of covered surface by small magnetic structures and its variation with the solar activity.
We present a database of 11 interplanetary shocks associated to coronal mass ejections (CMEs) observed by STEREO and Wind missions between 2006 and 2011 that show evidence of Type II radio burst. For all events, we calculated the principal characteristics of the shock driver, the intensity and geometrical configuration of the in-situ shock and checked for the existence of in-situ type II radio burst. We made a comparative analysis of two CME events (on 18 August 2010 and 4 June 2011), which are apparently associated to two or more magnetic structures which interact in space (i.e. CMEs, SIRs, CIRs). These events show varied shock configurations and intensities. We found evidence of in-situ type II radio bursts in one of the events studied, suggesting that the geometry of the shock (quasi-perpendicularity) is also critical for the generation and/or detection of radio emission in-situ.
Magnetic instability is a key consideration for filament eruptions and subsequent CMEs. In this contribution we are considering different magnetic conditions for active and non-active regions, such as coronal hole regions and quiet sun, and also active regions of a simple magnetic configuration. The aim is to assess magnetic instability through potential and non-potential field modelling and 3D evaluation of the magnetic decay index. Some eruptive examples from solar cycle 24 using HMI/SDO data are presented, complemented with observations of AIA/SDO.
Initiation and development of a M 1.0 class flare of June 12, 2014, was observed by space and ground-based telescopes, including EUV and X-ray imaging spectroscopy by IRIS and RHESSI, and high-resolution optical imaging by 1.6 m New Solar Telescope (NST). Analyzing the NST data, we found small-scale loop-like structures in the region of the magnetic field Polarity Inversion Line (PIL), the emergence and interaction of which caused photospheric brightenings temporarily coinciding with hard X-ray impulses. Detailed studies of the PIL region reveal signatures of photospheric plasma downflows and dissipation of electric currents. The reconstructed magnetic field topology shows a bundle of lines connecting the PIL region with the flare ribbons which were places of chromospheric evaporation observed by IRIS. The observations suggest a scenario with the primary energy release processes located in the low atmospheric layers of the PIL, energizing the overlying large-scale magnetic structure and causing “gentle” chromospheric evaporation.