Mixing 4D-Equipped and Unequipped Aircraft in the Terminal Area

On-board 4D guidance systems, which predict and control the touchdown time of an aircraft to an accuracy of a few seconds throughout the descent, were developed and demonstrated in several flight test programs. However, in addition to refinements of the on board system, two important issues still need to be considered. First, in order to make effective use of these on-board systems, it is necessary to understand and develop the interactions of the airborne and air traffic control (ATC) system in the proposed advanced environment. Unless the total system is understood, the advanced on-board system may prove unusable from an ATC standpoint. Second, in planning for a future system in which all aircraft are 4D equipped, it is necessary to confront the transition situation in which some percentage of traffic must still be handled by conventional means. In terms of 4D, this means that some traffic must still be given radar vectors and speed clearances (that is, be spaced by conventional distance separation techniques), while the 4D-equipped aircraft need to be issued time assignments. These apparent differences are reconciled and efficient ATC operation is developed

Simulation studies of time-control procedures for the advanced air traffic control system

The problem of mixing aircraft equipped with time-controlled guidance systems and unequipped aircraft in the terminal area has been investigated via a real-time air traffic control simulation. These four-dimensional (4D) guidance systems can predict and control the touchdown time of an aircraft to an accuracy of a few seconds throughout the descent. The objectives of this investigation were to (1) develop scheduling algorithms and operational procedures for various traffic mixes that ranged from 25% to 75% 4D-equipped aircraft; (2) examine the effect of time errors at 120 n. mi. from touchdown on touchdown time scheduling of the various mix conditions; and (3) develop efficient algorithms and procedures to null the initial time errors prior to reaching the final control sector, 30 n. mi. from touchdown. Results indicate substantial reduction in controller workload and an increase in orderliness when more than 25% of the aircraft are equipped with 4D guidance systems; initial random errors of up to + or - 2 min can be handled via a single speed advisory issued in the arrival control sector, thus avoiding disruption of the time schedule

CONTRIBUTIONS TO THE BRYOPHYTE FLORA OF THE KOMOVI MTS (MONTENEGRO)

As a result of several field trips made into the Komovi Mts, 200 bryophyte taxa (43 liverworts and 157 mosses) were collected. Four species are reported for the first time in the country. Among the species recorded, six are red-listed in Europe

Adaptive Trajectory Prediction Algorithm for Climbing Flights

Aircraft climb trajectories are difficult to predict, and large errors in these predictions reduce the potential operational benefits of some advanced features for NextGen. The algorithm described in this paper improves climb trajectory prediction accuracy by adjusting trajectory predictions based on observed track data. It utilizes rate-of-climb and airspeed measurements derived from position data to dynamically adjust the aircraft weight modeled for trajectory predictions. In simulations with weight uncertainty, the algorithm is able to adapt to within 3 percent of the actual gross weight within two minutes of the initial adaptation. The root-mean-square of altitude errors for five-minute predictions was reduced by 73 percent. Conflict detection performance also improved, with a 15 percent reduction in missed alerts and a 10 percent reduction in false alerts. In a simulation with climb speed capture intent and weight uncertainty, the algorithm improved climb trajectory prediction accuracy by up to 30 percent and conflict detection performance, reducing missed and false alerts by up to 10 percent

Towards a red List of the Albanian Bryophytes

Among the SE European countries Albania has the least known bryophyte flora. A bryophyte red list is lacking as well. Since it is not yet possible to use the IUCN criteria guidelines proposed for bryophytes, the aim of the present contribution is to compile a list of the bryophyte taxa from Al- bania with, wherever possible, the inclusion of conservational values, according to the European Bryophyte Red Data Book or other regional red lists (e.g. those existing for Serbia, Montenegro, Bulgaria and Romania). Hence, 16 liverwort species (ca 17% of the total) and 64 moss species (ca 18%) are taken into account. For an improved red list of the bryophytes of Albania extensive ex- ploration and collecting is greatly needed in the country. The hereby presented account should be considered as a tentative one. This preliminary version of a red list is provided with the aim to highlight the “national red list candidate” bryophyte species, which might need to be included in further natural heritage conservation initiatives in Albania. Even until then it is clear that there is an urgent need for the protection of the bryophytes in Albania

Structural Synergy and Molecular Crosstalk between Bacterial Helicase Loaders and Replication Initiators

SummaryThe loading of oligomeric helicases onto replication origins marks an essential step in replisome assembly. In cells, dedicated AAA+ ATPases regulate loading, however, the mechanism by which these factors recruit and deposit helicases has remained unclear. To better understand this process, we determined the structure of the ATPase region of the bacterial helicase loader DnaC from Aquifex aeolicus to 2.7 Å resolution. The structure shows that DnaC is a close paralog of the bacterial replication initiator, DnaA, and unexpectedly shares an ability to form a helical assembly similar to that of ATP-bound DnaA. Complementation and ssDNA-binding assays validate the importance of homomeric DnaC interactions, while pull-down experiments show that the DnaC and DnaA AAA+ domains interact in a nucleotide-dependent manner. These findings implicate DnaC as a molecular adaptor that uses ATP-activated DnaA as a docking site for regulating the recruitment and correct spatial deposition of the DnaB helicase onto origins

Selecting and implementing overview methods: implications from five exemplar overviews

This is the final version of the article. Available from BioMed Central via the DOI in this record.Background Overviews of systematic reviews are an increasingly popular method of evidence synthesis; there is a lack of clear guidance for completing overviews and a number of methodological challenges. At the UK Cochrane Symposium 2016, methodological challenges of five overviews were explored. Using data from these five overviews, practical implications to support methodological decision making of authors writing protocols for future overviews are proposed. Methods Methods, and their justification, from the five exemplar overviews were tabulated and compared with areas of debate identified within current literature. Key methodological challenges and implications for development of overview protocols were generated and synthesised into a list, discussed and refined until there was consensus. Results Methodological features of three Cochrane overviews, one overview of diagnostic test accuracy and one mixed methods overview have been summarised. Methods of selection of reviews and data extraction were similar. Either the AMSTAR or ROBIS tool was used to assess quality of included reviews. The GRADE approach was most commonly used to assess quality of evidence within the reviews. Eight key methodological challenges were identified from the exemplar overviews. There was good agreement between our findings and emerging areas of debate within a recent published synthesis. Implications for development of protocols for future overviews were identified. Conclusions Overviews are a relatively new methodological innovation, and there are currently substantial variations in the methodological approaches used within different overviews. There are considerable methodological challenges for which optimal solutions are not necessarily yet known. Lessons learnt from five exemplar overviews highlight a number of methodological decisions which may be beneficial to consider during the development of an overview protocol.The overview conducted by Pollock [19] was supported by a project grant from the Chief Scientist Office of the Scottish Government. The overview conducted by McClurg [21] was supported by a project grant by the Physiotherapy Research Foundation. The overview by Hunt [22] was supported as part of doctoral programme funding by the National Institute for Health Research (NIHR) Collaboration for Leadership in Applied Health Research and Care South West Peninsula (PenCLAHRC). The overview conducted by Estcourt [20] was supported by an NIHR Cochrane Programme Grant for the Safe and Appropriate Use of Blood Components. The overview conducted by Brunton [23] was commissioned by the Department of Health as part of an ongoing programme of work on health policy research synthesis. Alex Pollock is employed by the Nursing, Midwifery and Allied Health Professions (NMAHP) Research Unit, which is supported by the Chief Scientist Office of the Scottish Government. Pauline Campbell is supported by the Chief Nurses Office of the Scottish Government

Molecular Landscape of the Ribosome Pre-initiation Complex during mRNA Scanning: Structural Role for eIF3c and Its Control by eIF5

Citation: Obayashi, E., Luna, R. E., Nagata, T., Martin-Marcos, P., Hiraishi, H., Singh, C. R., . . . Asano, K. (2017). Molecular Landscape of the Ribosome Pre-initiation Complex during mRNA Scanning: Structural Role for eIF3c and Its Control by eIF5. Cell Reports, 18(11), 2651-2663. doi:10.1016/j.celrep.2017.02.052During eukaryotic translation initiation, eIF3 binds the solvent-accessible side of the 40S ribosome and recruits the gate-keeper protein eIF1 and eIF5 to the decoding center. This is largely mediated by the N-terminal domain (NTD) of eIF3c, which can be divided into three parts: 3c0, 3c1, and 3c2. The N-terminal part, 3c0, binds eIF5 strongly but only weakly to the ribosome-binding surface of eIF1, whereas 3c1 and 3c2 form a stoichiometric complex with eIF1. 3c1 contacts eIF1 through Arg-53 and Leu-96, while 3c2 faces 40S protein uS15/S13, to anchor eIF1 to the scanning pre-initiation complex (PIC). We propose that the 3c0:eIF1 interaction diminishes eIF1 binding to the 40S, whereas 3c0:eIF5 interaction stabilizes the scanning PIC by precluding this inhibitory interaction. Upon start codon recognition, interactions involving eIF5, and ultimately 3c0:eIF1 association, facilitate eIF1 release. Our results reveal intricate molecular interactions within the PIC, programmed for rapid scanning-arrest at the start codon

Molecular Architecture of the 40S⋅eIF1⋅eIF3 Translation Initiation Complex

Eukaryotic translation initiation requires the recruitment of the large, multiprotein eIF3 complex to the 40S ribosomal subunit. Using X-ray structures of all major components of the minimal, six-subunit Saccharomyces cerevisiae eIF3 core, together with cross-linking coupled to mass spectrometry, we were able to use IMP to position and orient all eIF3 components on the 40S•eIF1 complex, revealing an extended, modular arrangement of eIF3 subunits. For more information about how to reproduce this modeling, see https://salilab.org/40S-eIF1-eIF3 or the README file

The Methanothermobacter thermautotrophicus ExoIII homologue Mth212 is a DNA uridine endonuclease

The genome of Methanothermobacter thermautotrophicus, as a hitherto unique case, is apparently devoid of genes coding for general uracil DNA glycosylases, the universal mediators of base excision repair following hydrolytic deamination of DNA cytosine residues. We have now identified protein Mth212, a member of the ExoIII family of nucleases, as a possible initiator of DNA uracil repair in this organism. This enzyme, in addition to bearing all the enzymological hallmarks of an ExoIII homologue, is a DNA uridine endonuclease (U-endo) that nicks double-stranded DNA at the 5′-side of a 2′-d-uridine residue, irrespective of the nature of the opposing nucleotide. This type of activity has not been described before; it is absent from the ExoIII homologues of Escherichia coli, Homo sapiens and Methanosarcina mazei, all of which are equipped with uracil DNA repair glycosylases. The U-endo activity of Mth212 is served by the same catalytic center as its AP-endo activity