Search

There is a consensus that the increasingly large number of LEO debris objects represents a major threat to both active and defunct satellites and that means a potential runaway collisional cascading. This problem urgently demands to be addressed immediately, since the number of satellites in LEO is also dramatically increasing. Many active space debris removal programs have been proposed and those based on using laser from space appear to be really promising, taking into account that one of the most challenging issues from the orbital standpoint is to guarantee the appropriate accuracy for the laser beams that are shot from space-based LEO trackers. In this work, we propose how to build up space-based laser brooms consisting of a significant number of autonomous LEO trackers aimed at performing surgical local shooting actions to deflect the most dangerous middle-size debris objects into the Atmosphere by means of laser ablation. The precision of these brooms lies in the use of the post-Newtonian equations for the computation of absolute and relative positions and velocities, as well as ranges. • Improving accuracy in JCA methods is an issue to remove LEO debris by laser actions. • Implementing p-N corrections is necessary to accurately carry out surgical actions. • Trackers with orbital inclinations larger than 90° may sweep the surrounding space. • Using a laser broom is an efficient and safe method to achieve the goal. [ABSTRACT FROM AUTHOR]

This work is aimed to introduce a strategy that may help reach the conclusion that using lasers in space is one of the most promising methods to reduce the risk of collisions between active satellites and middle-size LEO debris. The strategy accounts for the implementation of the post-Newtonian (p-N) corrections that are decisive to reach the accuracy required by some Just-in-Time Collision Avoidance (JCA) space-based methods. In fact, we show how and why all JCA methods similar to the one introduced here, which involves simple formations of trackers in Sun-synchronous orbits (SSO), would be within the most efficient to throw middle size debris objects into the Atmosphere by laser ablation, as long as the trackers can implement these corrections while the objects are targeted. • Improving accuracy in JCA methods is an issue to remove LEO debris by laser actions. • The trackers in SSO able to implement p-N corrections may improve the accuracy. • Using formations of these trackers is an efficient mean to get the goal. [ABSTRACT FROM AUTHOR]

In dieser Studie wurden verschiedene Messungen kombiniert, darunter der regionale zerebrale Blutfluss („regional cerebral blood flow", rCBF) und die Herzfrequenzvariabilität („heart rate variability", HRV), um longitudinale Veränderungen in den Interaktionen zwischen Gehirn und Herz bei Patient*innen mit chronischen Kreuzschmerzen nach einer osteopathischen Behandlung zu untersuchen. Dazu wurden 32 rechtshändige Patient*innen randomisiert und in Gruppen mit 4 wöchentlichen osteopathischen (n = 16) oder Sham-Behandlungen (n = 16) aufgeteilt. Die Teil-nehmer*innen waren 42,3 ± 7,3 Jahre alt (20 Männer, 12 Frauen) und litten unter Kreuzschmerzen (Dauer: 14,6 ± 8,0 Monate). Am Ende der Studie wiesen die Patient* innen, die osteopathisch behandelt worden waren, einen verringerten rCBF in mehreren Regionen auf, die zur Schmerzmatrix gehören (linke hintere Insula, linker anteriorer cingulärer Kortex, linker Thalamus), ebenso in sensorischen Regionen (linker superiorer Parietallappen), im mittleren Frontallappen und linken Cuneus. Demgegenüber war der rCBF in der Osteopathie-Gruppe im Vergleich zur Sham-Gruppe in der rechten anterioren Insula, dem bilateralen Striatum, dem linken posterioren cingulären Kortex, dem rechten präfrontalen Kortex, dem linken Zerebellum und dem rechten ventroposterioren lateralen Thalamus erhöht. Nach osteopathischer Behandlung zeigte sich eine statistisch signifikante negative Korrelation zwischen den HRV-Änderungen im hochfrequenten Bereich und den rCBF-Änderungen bei T2 in der linken posterioren Insula und dem bilateralen Nucleus lentiformis. Dieselben Hirnregionen zeigten eine positive Korrelation zwischen rCBF-Änderungen und HRV-Änderungen im niederfrequenten Bereich bei T2. Diese Ergebnisse deuten darauf hin, dass die osteopathische Behandlung eine wichtige Rolle bei der Regulierung der Interaktionsmechanismen zwischen Gehirn und Herz spielen kann. In this study we used a combination of measures including regional cerebral blood flow (rCBF) and heart rate variability (HRV) to investigate brain–heart correlates of longitudinal baseline changes of chronic low back pain (cLBP) after osteopathic manipulative treatment (OMT). Thirty-two right-handed patients were randomised and divided into 4 weekly session of OMT (n = 16) or Sham (n = 16). Participants aged 42.3 ± 7.3 (M/F: 20/12) with cLBP (duration: 14.6 ± 8.0 months). At the end of the study, patients receiving OMT showed decreased baseline rCBF within several regions belonging to the pain matrix (left posterior insula, left anterior cingulate cortex, left thalamus), sensory regions (left superior parietal lobe), middle frontal lobe and left cuneus. Conversely, rCBF was increased in right anterior insula, bilateral striatum, left posterior cingulate cortex, right prefrontal cortex, left cerebellum and right ventroposterior lateral thalamus in the OMT group as compared with sham. OMT showed a statistically significant negative correlation between baseline high frequency HRV changes and rCBF changes at T2 in the left posterior insula and bilateral lentiform nucleus. The same brain regions showed a positive correlation between rCBF changes and low frequency HRV baseline changes at T2. These findings suggest that OMT can play a significant role in regulating brain–heart interaction mechanisms. [ABSTRACT FROM AUTHOR]

Both artificial and biological systems are faced with the challenge of noisy and uncertain estimation of the state of the world, in contexts where feedback is often delayed. This challenge also applies to the processes of language production and comprehension, both when they take place in isolation (e.g., in monologue or solo reading) and when they are combined as is the case in dialogue. Crucially, we argue, dialogue brings with it some unique challenges. In this paper, we describe three such challenges within the general framework of control theory, drawing analogies to mechanical and biological systems where possible: (1) the need to distinguish between self- and other-generated utterances; (2) the need to adjust the amount of advance planning (i.e., the degree to which planning precedes articulation) flexibly to achieve timely turn-taking; (3) the need to track changing conversational goals. We show that message-to-sound models of language production (i.e., those that cover the whole process from message generation to articulation) tend to implement fairly simple control architectures. However, we argue that more sophisticated control architectures are necessary to build language production models that can account for both monologue and dialogue. • Theories of monitoring account for how speakers control language production in monologue. • Language production in dialogue involves additional control challenges. • Distinguishing self- and other-generated utterances requires paired forward-inverse models. • Flexible planning requires simulation of the consequences of different production choices. • Tracking changing conversational goals requires adaptive intermittent control. [ABSTRACT FROM AUTHOR]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.dsr.2006.05.003 Byline: Cristina Gambi, Roberto Danovaro Keywords: Spatial distribution; Temporal variation; Mediterranean Sea; Deep sea; Meiofauna Abstract: In order to identify environmental factors driving the distribution and functioning of deep-sea fauna and the spatial scales of interactions, we carried out a multiple-scale investigation in the Mediterranean basin in which we compared two bathyal plains, located at the same depth (ca. 3000m), but characterised by contrasting trophic conditions. We investigated meiofaunal abundance, biomass, community structure and biodiversity (expressed as richness of taxa) in relation to sediment characteristics, downward fluxes and food availability in the sediment. Samples were collected at all spatial scales (from small to macroscale) in two seasons. Our results indicated that deep-sea systems with different trophic conditions displayed different responses to the distribution of available energy and its spatio-temporal variability in the sediment. The analysis at a macroscale (>1000km) indicated that meiofauna were controlled primarily by the trophic inputs to the deep-sea system. Spatial variability of meiofaunal parameters at a mesoscale (>50km) was highest in the eastern Mediterranean and lowest in the western Mediterranean. Such differences are the consequence of the unpredictable inputs of organic matter in the oligotrophic eastern Mediterranean versus a more homogeneous distribution of food inputs in the mesotrophic western Mediterranean. At a smaller scale (local scale 7km), in the western Mediterranean, the distribution of meiofaunal parameters was highly homogeneous, reflecting the homogeneous distribution of the food availability in the sediment. Our results indicated that the highly variable input and distribution of food sources in the deep eastern Mediterranean did not provide any 'insurance' for the sustainability of the deep-sea faunal assemblages in the long term, thus leading to an uncoupling between resource availability and distribution of organisms. We conclude that the influence of energy availability on the deep-sea faunal distributions change at different spatial scales and that the analysis of spatial variability at mesoscales is crucial for understanding the relationships between deep-sea benthic fauna and environmental drivers. Author Affiliation: Dipartimento di Scienze del Mare, Facolta di Scienze, Universita Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy Article History: Received 16 September 2005; Revised 8 May 2006; Accepted 10 May 2006

Decreasing ocean surface pH, called ocean acidification (OA), is among the major risks for marine ecosystems due to human-driven atmospheric p CO 2 increase. Understanding the molecular mechanisms of adaptation enabling marine species to tolerate a lowered seawater pH could support predictions of consequences of future OA scenarios for marine life. This study examined whether the ATP-binding cassette (ABC)-like gene slr2019 confers tolerance to the marine cyanobacterium Halomicronema metazoicum to low seawater pH conditions (7.7, 7.2, 6.5) in short- and long-term exposures (7 and 30 d). Photosynthetic pigment content indicated that the species can tolerate all three lowered-pH conditions. At day 7, slr2019 was up-regulated at pH 7.7 while no changes were observed at lower pH. After 30-d exposure, a significant decrease in slr2019 transcript levels was observed in all low-pH treatments. These first results indicate an effect of low pH on the examined transporter expression in H. metazoicum. [Display omitted] • The involvement of ABC transporters in bacterial acid stress resistance was tested. • The Cyanobacterium H. metazoicum demonstrated tolerance towards low pH environments. • The ABC slr2019 -like gene is differentially expressed under low pH conditions. • A new RNA extraction method for H. metazoicum mattes was developed. [ABSTRACT FROM AUTHOR]

Research on the Atacama Trench shows that high meiofaunal density is determined more by organic matter quality rather than quantity. Nematodes make up for over 80% of total meiofaunal density, and body size was found to decrease by up to 40% in hadal sediments.