Growing massive black holes through super-critical accretion of stellar-mass seeds

The rapid assembly of the massive black holes that power the luminous quasars observed at $z \sim 6-7$ remains a puzzle. Various direct collapse models have been proposed to head-start black hole growth from initial seeds with masses $\sim 10^5\,\rm M_\odot$, which can then reach a billion solar mass while accreting at the Eddington limit. Here we propose an alternative scenario based on radiatively inefficient super-critical accretion of stellar-mass holes embedded in the gaseous circum-nuclear discs (CNDs) expected to exist in the cores of high redshift galaxies. Our sub-pc resolution hydrodynamical simulations show that stellar-mass holes orbiting within the central 100 pc of the CND bind to very high density gas clumps that arise from the fragmentation of the surrounding gas. Owing to the large reservoir of dense cold gas available, a stellar-mass black hole allowed to grow at super-Eddington rates according to the "slim disc" solution can increase its mass by 3 orders of magnitudes within a few million years. These findings are supported by simulations run with two different hydro codes, RAMSES based on the Adaptive Mesh Refinement technique and GIZMO based on a new Lagrangian Godunov-type method, and with similar, but not identical, sub-grid recipes for star formation, supernova feedback, black hole accretion and feedback. The low radiative efficiency of super-critical accretion flows are instrumental to the rapid mass growth of our black holes, as they imply modest radiative heating of the surrounding nuclear environment.Comment: 12 pages, 8 figures, 2 tables. Accepted for publication in MNRA

Effects of male to female ratio and number of females per nesting tunnel on sex ratio and number of progeny of the alfalfa leafcutter bee Megachile rotundata (Hymenoptera: Megachilidae)

This paper reports the results of two 3-year studies on the effects of: 1) the ratio of males to females in the parental generation on percent female progeny; and 2) the ratio of females to nesting tunnels on percent female progeny. In study 1): there were no significant differences between treatments in percent females in the progeny or total number of nesting cells produced each year. The average percentages of females were 22% in 1990, 27% in 1991, and 28% in 1992. In study 2): there were significantly fewer female progeny with 2 females per tunnel in 1991, and in all years, significantly fewer progeny when the females were crowded. The total number of cells produced was inversely related to crowding with ratios of females per tunnel of 1:2, 1:1 and 2:1.Key words: alfalfa leafcutter bee; Megachile rotundata; alfalfa see

The Emotional Self-Efficacy Scale: Adaptation and Validation for Young Adolescents

Emotional self-efficacy (ESE) is an important aspect of emotional functioning, with current measures for children and adolescents focused on the measurement of self-beliefs in relation to the management of emotions. In the present study, we report the psychometric properties of the first adaptation of the Emotional Self-Efficacy Scale for youth (Youth-ESES) that measures additional aspects of ESE, such as perceiving and understanding emotions and helping others modulate their emotions. Participants were 192 young adolescents aged 11 to 13 years from a U.K. state school. They completed the Youth-ESES and measures of ability emotional intelligence (EI) and cognitive ability. Results support the same four-factor structure that has been previously documented using the adult version of the ESES, with the four subscales being largely independent from cognitive ability and only moderately related to ability EI. However, the four subscales were less differentiated in the present study compared with adult data previously published, suggesting that there is a strong general factor underlying young adolescents’ ESE scores. Overall, the results suggest that the adapted Youth-ESES can be reliably used with youth, and that confidence in how a young person feels about his or her emotional functioning remains distinct from emotional skill

Algorithm for the Calculation of Geodetic Distances for Maritime Jurisdictional Boundaries

This paper presents an algorithm which can be applied for the calculations of distances of hundred kilometres from the co-ordinates of their end points. Analysis of the simplifications are also presented and could be adopted for applications related to the Law of the Sea

Differential motor unit changes after endurance or high-intensity interval training.

PURPOSE: Using a novel technique of high-density surface electromyography (HDEMG) decomposition and motor unit (MU) tracking, we compared changes in the properties of vastus medialis (VM) and vastus lateralis (VL) MUs following endurance (END) and high-intensity interval training (HIIT). METHODS: Sixteen men were assigned to an END or HIIT group (n=8 each) and performed six training sessions over 14 days. Each session consisted of 8-12×60s intervals at 100% peak power output (PPO) separated by 75s of recovery (HIIT) or 90-120min continuous cycling at ~65% VO2peak (END). Pre and post intervention, participants performed: 1) incremental cycling to determine VO2peak and PPO and 2) maximal (MVC), submaximal (10, 30, 50 and 70% MVC) and sustained (until task failure at 30% MVC) isometric knee extensions while HDEMG signals were recorded from the VM and VL. EMG signals were decomposed (submaximal contractions) into individual MUs by convolutive blind source separation. Finally, MUs were tracked across sessions by semi-blind source separation. RESULTS: After training, END and HIIT improved VO2peak similarly (by 5.0 and 6.7%, respectively). The HIIT group showed enhanced maximal knee extension torque by ~7% (p=0.02) and was accompanied by an increase in discharge rate for high-threshold MUs (≥50% knee extension MVC) (p0.05). CONCLUSIONS: HIIT and END induce different adjustments in MU discharge rate despite similar improvements in cardiopulmonary fitness. Moreover, the changes induced by HIIT are specific for high-threshold motor units. For the first time we show that HIIT and END induce specific neuromuscular adaptations, possibly related to differences in exercise load intensity and training volume

Evaluation of monitoring methods for western flower thrips, Frankliniella occidentalis (Thysanoptera: Thripidae), during the blossom period of 'Granny Smith' apples

Commercial sticky board traps (150 x 100 mm) of three different colors (blue, white or yellow) were treated with one of two chemical attractants (p-anisaldehyde and ethyl nicotinate) and with the solvent ethanol. Blue and white traps caught four and three times more thrips respectively than yellow traps. Attractants improved catches by only about 20% and were not considered economical. If traps are used, a plain blue trap is recommended. Trapping, beating tray and flower cluster flicking monitoring methods were compared. Trapping gave a time-averaged indication of thrips numbers, but numbers are probably affected by location of the trap and flowering stage of the apple. The beating tray method was the most versatile. It could be used regardless of flower condition and produced instant results. The currently recommended flower cluster flicking method produced few thrips and is affected by condition and age of the flowers, as well as time of day. We conclude that it is an ineffective method. Monitoring thrips numbers after blossom using a beating tray may give more practical economic thresholds for treatment.Key words: thrips; apples; Frankliniella occidentali

Lithostratigraphy, biostratigraphy, and stable-isotope stratigraphy of cores from ODP Leg 105 site surveys, Labrador Sea and Baffin Bay

Trigger weight (TWC) and piston (PC) cores obtained from surveys of the three sites drilled during Ocean Drilling Program (ODP) Leg 105 were studied in detail for benthic foraminiferal assemblages, total carbonate (all sites), planktonic foraminiferal abundances (Sites 645 and 647), and stable isotopes (Sites 646 and 647). These high-resolution data provide the link between modern environmental conditions represented by the sediment in the TWC and the uppermost cores of the ODP holes. This link provides essential control data for interpretating late Pleistocene paleoceanographic records from these core holes. At Site 645 in Baffin Bay, local correlation is difficult because the area is dominated by ice-rafted deposits and by debris flows and/or turbidite sedimentation. At the two Labrador Sea sites (646 and 647), the survey cores and uppermost ODP cores can be correlated. High-resolution data from the site survey cores also provide biostratigraphic data that refine the interpretations compiled from core-catcher samples at each ODP site

Tracking motor units longitudinally across experimental sessions with high-density surface electromyography.

KEY POINTS: Classic motor unit (MU) recording and analysis methods do not allow the same MUs to be tracked across different experimental sessions, and therefore, there is limited experimental evidence on the adjustments in MU properties following training or during the progression of neuromuscular disorders. We propose a new processing method to track the same MUs across experimental sessions (separated by weeks) by using high-density surface electromyography. The application of the proposed method in two experiments showed that individual MUs can be identified reliably in measurements separated by weeks and that changes in properties of the tracked MUs across experimental sessions can be identified with high sensitivity. These results indicate that the behaviour and properties of the same MUs can be monitored across multiple testing sessions. The proposed method opens new possibilities in the understanding of adjustments in motor unit properties due to training interventions or the progression of pathologies. ABSTRACT: A new method is proposed for tracking individual motor units (MUs) across multiple experimental sessions on different days. The technique is based on a novel decomposition approach for high-density surface electromyography and was tested with two experimental studies for reliability and sensitivity. Experiment I (reliability): ten participants performed isometric knee extensions at 10, 30, 50 and 70% of their maximum voluntary contraction (MVC) force in three sessions, each separated by 1 week. Experiment II (sensitivity): seven participants performed 2 weeks of endurance training (cycling) and were tested pre-post intervention during isometric knee extensions at 10 and 30% MVC. The reliability (Experiment I) and sensitivity (Experiment II) of the measured MU properties were compared for the MUs tracked across sessions, with respect to all MUs identified in each session. In Experiment I, on average 38.3% and 40.1% of the identified MUs could be tracked across two sessions (1 and 2 weeks apart), for the vastus medialis and vastus lateralis, respectively. Moreover, the properties of the tracked MUs were more reliable across sessions than those of the full set of identified MUs (intra-class correlation coefficients ranged between 0.63-0.99 and 0.39-0.95, respectively). In Experiment II, ∼40% of the MUs could be tracked before and after the training intervention and training-induced changes in MU conduction velocity had an effect size of 2.1 (tracked MUs) and 1.5 (group of all identified motor units). These results show the possibility of monitoring MU properties longitudinally to document the effect of interventions or the progression of neuromuscular disorders

Διευρύνοντας το Μεθοδολογικό πλάισιο των Ολοκληρωμένων Μοντέλων Χρήσεων-Γης και Μεταφορών: Χωρικά Οικονομετρικά Μοντέλα και Αξιολόγηση Πολιτικών

323 σ.Στην παρούσα εργασία εξετάζεται η διεύρυνση του μεθοδολογικού πλαισίου των Όλοκληρωμένων Μοντέλων Χρήσεων-Γης και Μεταφορών σε κάθε επίπεδο. Οι προτεινόμενες βελτιώσεις αποσκοπούν στην αύξηση των ικανοτήτων πρόβλεψης, αξιοποιώντας τα οφέλη της μικροπροσομοίωσης σε τρείς διαστάσεις, άτομο, χώρο και χρόνο, με σκοπό να καταστόύν τα μοντέλα αυτά ευέλικτα εργαλεία αξιολοόγησης πολιτικών.In this research, the methodological framework of the Integrated Land-Use and Transport (LUTI) models is extended at every level. The objective of developing and implementing LUTI models is to predict the direct and indirect impacts of –transport and land-use– policies, on the environment, the society and the economy. The proposed improvements aim to increase the predicting capabilities of the current LUTI models, exploiting the strengths of microsimulation in three dimensions, agents, space and time, in order to render them flexible platforms for policy evaluation. The effects of the current economic crisis are discussed and explored throughout the doctoral dissertation. Aiming to decrease the required budget for a LUTI model development, public on-line data are used to a large part of the analysis. Moreover, a graph-theoretic solution for associations generation in synthetic simulation is suggested. Different types of spatial econometric models are used for the development of real estate price models, which form fundamental component of every LUTI model. Urban quality indicators (i.e. accessibility, population segregation, economic viability, available open space, housing affordability, land-use and social mix, and building density) are effectively employed manifesting the benefits of trans-disciplinary collaboration in urban planning. In this research, a policy evaluation methodology based on distributions rather than single aggregate measures of quality indicators is proposed. The results indicate that spatial econometrics effectively remove the spatial autocorrelation and achieve higher accuracy than the traditional linear regression, in predicting the dwelling prices. The impact of transportation infrastructure locations on real estate purchase prices and rents differs, depending on the type of the transit system. Qualitative transit infrastructure has preserved the real estate prices at higher levels during the crisis. Synthetic populations and real, on-line, crowdsourced data can efficiently be used for the development of LUTI models. Finally, agent-based LUTI models provide an opportunity for the development of an improved, flexible policy evaluation platform.Δημήτριος Β. Ευθυμίο