scholarly journals Determination of Venus’ Interior Structure with EnVision

2021 ◽  
Vol 13 (9) ◽  
pp. 1624
Author(s):  
Pascal Rosenblatt ◽  
Caroline Dumoulin ◽  
Jean-Charles Marty ◽  
Antonio Genova
Keyword(s):  
Phase Lag ◽  
The Core ◽  
Cosmic Vision ◽  
Mantle Viscosity ◽  
Geological Features ◽  
Low Altitude ◽  
The Moment ◽  
Lateral Variations ◽  
Better Than

The Venusian geological features are poorly gravity-resolved, and the state of the core is not well constrained, preventing an understanding of Venus’ cooling history. The EnVision candidate mission to the ESA’s Cosmic Vision Programme consists of a low-altitude orbiter to investigate geological and atmospheric processes. The gravity experiment aboard this mission aims to determine Venus’ geophysical parameters to fully characterize its internal structure. By analyzing the radio-tracking data that will be acquired through daily operations over six Venusian days (four Earth’s years), we will derive a highly accurate gravity field (spatial resolution better than ~170 km), allowing detection of lateral variations of the lithosphere and crust properties beneath most of the geological features. The expected 0.3% error on the Love number k2, 0.1° error on the tidal phase lag and 1.4% error on the moment of inertia are fundamental to constrain the core size and state as well as the mantle viscosity.

Time and Latitude in South Africa

1972 ◽  
Vol 1 ◽  
pp. 27-38
Author(s):  
J. Hers
Keyword(s):  
South Africa ◽  
Cape Town ◽  
Astronomical Observations ◽  
Royal Observatory ◽  
The Republic ◽  
Astronomical Determination ◽  
Limited Accuracy ◽  
Better Than

In South Africa the modern outlook towards time may be said to have started in 1948. Both the two major observatories, The Royal Observatory in Cape Town and the Union Observatory (now known as the Republic Observatory) in Johannesburg had, of course, been involved in the astronomical determination of time almost from their inception, and the Johannesburg Observatory has been responsible for the official time of South Africa since 1908. However the pendulum clocks then in use could not be relied on to provide an accuracy better than about 1/10 second, which was of the same order as that of the astronomical observations. It is doubtful if much use was made of even this limited accuracy outside the two observatories, and although there may – occasionally have been a demand for more accurate time, it was certainly not voiced.

Imaging of ribosomal RNA-protein interactions by dark-field STEM

1989 ◽  
Vol 47 ◽  
pp. 250-251
Author(s):  
M. Boublik ◽  
V. Mandiyan ◽  
S. Tumminia ◽  
J.F. Hainfeld ◽  
J.S. Wall
Keyword(s):  
Nucleic Acid ◽  
16S Rrna ◽  
Dark Field ◽  
Radius Of Gyration ◽  
Central Domain ◽  
The Core ◽  
16S Rna ◽  
30S Subunit ◽  
Core Particles

Success in protein-free deposition of native nucleic acid molecules from solutions of selected ionic conditions prompted attempts for high resolution imaging of nucleic acid interactions with proteins, not attainable by conventional EM. Since the nucleic acid molecules can be visualized in the dark-field STEM mode without contrasting by heavy atoms, the established linearity between scattering cross-section and molecular weight can be applied to the determination of their molecular mass (M) linear density (M/L), mass distribution and radius of gyration (RG). Determination of these parameters promotes electron microscopic imaging of biological macromolecules by STEM to a quantitative analytical level. This technique is applied to study the mechanism of 16S rRNA folding during the assembly process of the 30S ribosomal subunit of E. coli. The sequential addition of protein S4 which binds to the 5'end of the 16S rRNA and S8 and S15 which bind to the central domain of the molecule leads to a corresponding increase of mass and increased coiling of the 16S rRNA in the core particles. This increased compactness is evident from the decrease in RG values from 114Å to 91Å (in “ribosomal” buffer consisting of 10 mM Hepes pH 7.6, 60 mM KCl, 2 m Mg(OAc)2, 1 mM DTT). The binding of S20, S17 and S7 which interact with the 5'domain, the central domain and the 3'domain, respectively, continues the trend of mass increase. However, the RG values of the core particles exhibit a reverse trend, an increase to 108Å. In addition, the binding of S7 leads to the formation of a globular mass cluster with a diameter of about 115Å and a mass of ∽300 kDa. The rest of the mass, about 330 kDa, remains loosely coiled giving the particle a “medusa-like” appearance. These results provide direct evidence that 16S RNA undergoes significant structural reorganization during the 30S subunit assembly and show that its interactions with the six primary binding proteins are not sufficient for 16S rRNA coiling into particles resembling the native 30S subunit, contrary to what has been reported in the literature.

The Final ‘Thank You’

Derrida Today ◽  
2010 ◽  
Vol 3 (1) ◽  
pp. 21-36
Author(s):  
Grant Farred
Keyword(s):  
South Africa ◽  
South African ◽  
Jacques Derrida ◽  
Political Transition ◽  
The Other ◽  
World Cup ◽  
The Core ◽  
Nelson Mandela ◽  
Black President ◽  
The Moment

‘The Final “Thank You”’ uses the work of Jacques Derrida and Friedrich Nietzsche to think the occasion of the 1995 rugby World Cup, hosted by the newly democratic South Africa. This paper deploys Nietzsche's Zarathustra to critique how a figure such as Nelson Mandela is understood as a ‘Superman’ or an ‘Overhuman’ in the moment of political transition. The philosophical focus of the paper, however, turns on the ‘thank yous’ exchanged by the white South African rugby captain, François Pienaar, and the black president at the event of the Springbok victory. It is the value, and the proximity and negation, of the ‘thank yous’ – the relation of one to the other – that constitutes the core of the article. 1

PREDICTION OF THE EFFICIENCY OF RECONSTRUCTIVE INTERVENTIONS ON THE MAJOR NERVES OF THE FOREARM, DEPENDING ON THE DEFECT DURATION AND THE FOLLOWING REHABILITATION

2020 ◽  
pp. 77-88
Author(s):  
Дмитрий Валериевич Судаков ◽  
Олег Валериевич Судаков ◽  
Людмила Валентиновна Кретинина ◽  
Наталья Владимировна Якушева ◽  
Артём Николаевич Шевцов
Keyword(s):  
Nervous Tissue ◽  
Clinical Situation ◽  
Economic Importance ◽  
Important Data ◽  
Subsequent Period ◽  
Complete Restoration ◽  
Reconstructive Microsurgery ◽  
The Moment

Статья посвящена построению прогноза эффективности реконструктивных вмешательств на магистральных нервах предплечья в зависимости от протяженности дефекта нервной ткани и особенностей последующего периода реабилитации пациентов. Данная тематика является весьма актуальной, так как с каждым годом во всем мире наблюдается определенный рост случаев травм различного генеза магистральных нервных стволов, которые затем нередко приводят к временной нетрудоспособности и даже инвалидности пациентов. Реконструктивная микрохирургия многие десятилетия пытается решить целый ряд проблем аутотрансплантации нервных стволов и повысить ее общую эффективность. Но из-за определенных проблем связанных с финансированием, некоторые вопросы трансплантологии и реабилитации остаются нерешенными и в настоящий момент. Все это придает представленной работе важное значение не только медицинского, но и социально - экономического плана. Целью работы стала попытка построения прогноза восстановительных операций на нервной ткани, с учетом объема пораженных структур и периода реабилитации. Объектами исследования стало 180 больных, которым по той или иной причине, осуществлялась реконструктивная операция на одном из магистральных нервов предплечья. Все пациенты были разделены на 3 группы по 60 человек, в зависимости от протяженности дефекта магистрального нерва: до 4 см, от 4 до 8 см и от 8 до 12 см. Последующее разделение внутри каждой группы на подгруппы производилось в зависимости от определенного поврежденного нерва (лучевой, локтевой, срединный). В работе изучалось течение раннего послеоперационного воспалительного процесса, с определением бактериальной микрофлоры в ране. Изучались и отдаленные последствия оперативного вмешательства. Своеобразной новизной для данной тематики в целом, стало выявление последующего установления инвалидности пациентов. Кроме того, важные данные были получены и по срокам реабилитации и частичного или полного восстановления утраченных функций по срокам в зависимости от размеров восстанавливаемого дефекта и от наличия или отсутствия необходимой реабилитации. Полученные в работе данные могут представлять интерес не только для врачей хирургов и травматологов, но и для организаторов здравоохранения, позволяя производить прогнозы по выздоровлению пациентов в каждой определенной клинической ситуации The article is devoted to the construction of a forecast of the effectiveness of reconstructive interventions on the main nerves of the forearm, depending on the length of the defect in the nervous tissue and the characteristics of the subsequent period of rehabilitation of patients. This topic is very relevant, since every year all over the world there is a certain increase in cases of injuries of various origins of the main nerve trunks, which then often lead to temporary disability and even disability of patients. For many decades, reconstructive microsurgery has been trying to solve a number of problems of autotransplantation of nerve trunks and improve its overall efficiency. But due to certain problems associated with funding, some issues of transplantation and rehabilitation remain unresolved at the moment. All this gives the presented work important not only medical, but also socio - economic importance. The aim of this work was to attempt to predict restorative operations on the nervous tissue, taking into account the volume of the affected structures and the period of rehabilitation. The objects of the study were 180 patients who, for one reason or another, underwent a reconstructive operation on one of the main nerves of the forearm. All patients were divided into 3 groups of 60 people, depending on the length of the main nerve defect: up to 4 cm, from 4 to 8 cm, and from 8 to 12 cm. Subsequent division within each group into subgroups was performed depending on the specific damaged nerve ( radial, ulnar, median). The work studied the course of the early postoperative inflammatory process, with the determination of bacterial microflora in the wound. The long-term consequences of surgery were also studied. A peculiar novelty for this topic as a whole was the identification of the subsequent establishment of disability in patients. In addition, important data were obtained on the timing of rehabilitation and partial or complete restoration of lost functions in terms of timing, depending on the size of the restored defect and on the presence or absence of the necessary rehabilitation. The data obtained in this work may be of interest not only for surgeons and traumatologists, but also for healthcare organizers, allowing them to make predictions about the recovery of patients in each specific clinical situation

Nauwkeurige methode voor de aanwasbepaling van het grondvlak met behulp van de Pressler-boor

1968 ◽  
Vol 12 ◽  
Author(s):  
R. Goossens
Keyword(s):  
Basal Area ◽  
Precise Determination ◽  
Maximum Diameter ◽  
Precise Method ◽  
Maximum Radius ◽  
The Core ◽  
Two Parameters

A precise method for the determination of the increment of the  basal area using the PressIer bore. Refering to  previous research showing that the basal area of the corsica pine could be  characterized by an ellips, we present in this paper a precise method for the  determination of the increment of the basal area. In this method we determine  the direction of the maximum diameter, we measure this diameter and we take a  core in one of the points of tangency of the caliper with the measured tree.  The determination of the diameter perpendicular to the maximum diameter  finishes the work wich is to be done in the forest. From the classical  measurements effectuated on the core and from the measured diameters we can  then determine the form (V) and the excentricity (e). Substituting these two  parameters in the formula 2 or 2', we can also calculate the error of a  radius measured on the core with respect to the representative radius, This  error with them allow us to correct the measured value of the minimum or the  maximum radius and we will be able to do a precise determination of the  increment.

Determination of trace concentrations of copper by FIA-FAAS after preconcentration on chelating sorbents

1989 ◽  
Vol 54 (7) ◽  
pp. 1785-1794 ◽  
Author(s):  
Vlastimil Kubáň ◽  
Josef Komárek ◽  
Zbyněk Zdráhal
Keyword(s):  
Sampling Frequency ◽  
Copper Determination ◽  
Flow Rates ◽  
Sample Injection ◽  
Injection Flow ◽  
Chelating Sorbents ◽  
Set Up ◽  
Trace Concentrations ◽  
Better Than

A FIA-FAAS apparatus containing a six-channel sorption equipment with five 3 x 26 mm microcolumns packed with Spheron Oxin 1 000, Ostsorb Oxin and Ostsorb DTTA was set up. Combined with sorption from 0.002M acetate buffer at pH 4.2 and desorption with 2M-HCl, copper can be determined at concentrations up to 100, 150 and 200 μg l-1, respectively. For sample and eluent flow rates of 5.0 and 4.0 ml min-1, respectively, and a sample injection time of 5 min, the limit of copper determination is LQ = 0.3 μg l-1, repeatability sr is better than 2% and recovery is R = 100 ± 2%. The enrichment factor is on the order of 102 and is a linear function of time (volume) of sample injection up to 5 min and of the sample injection flow rate up to 11 ml min-1 for Spheron Oxin 1 000 and Ostsorb DTTA. For times of sorption of 60 and 300 s, the sampling frequency is 70 and 35 samples/h, respectively. The parameters of the FIA-FAAS determination (acetylene-air flame) are comparable to or better than those achieved by ETA AAS. The method was applied to the determination of traces of copper in high-purity water.

scholarly journals Measuring the quartic Higgs self-coupling at a multi-TeV muon collider

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
M. Chiesa ◽  
F. Maltoni ◽  
L. Mantani ◽  
B. Mele ◽  
F. Piccinini ◽  
...  
Keyword(s):  
Higgs Boson ◽  
Center Of Mass ◽  
Mass Energy ◽  
Simple Analysis ◽  
Proton Proton ◽  
Coupling Interaction ◽  
Center Of Mass Energy ◽  
Muon Collider ◽  
Better Than

Abstract Measuring the shape of the Higgs boson potential is of paramount importance, and will be a challenging task at current as well as future colliders. While the expectations for the measurement of the trilinear Higgs self-coupling are rather promising, an accurate measurement of the quartic self-coupling interaction is presently considered extremely challenging even at a future 100 TeV proton-proton collider. In this work we explore the sensitivity that a muon collider with a center of mass energy in the multi-TeV range and luminosities of the order of 1035cm−2s−1, as presently under discussion, might provide, thanks to a rather large three Higgs-boson production and to a limited background. By performing a first and simple analysis, we find a clear indication that a muon collider could provide a determination of the quartic Higgs self-coupling that is significantly better than what is currently considered attainable at other future colliders.

Formation of an Iron(III) Oxo Cubane Core Fe4(μ4-O)4 from FeCl3 and the Unsymmetrical Tripodal Ligand N[(CH2CH2NH2)(CH2CH2OH)(CH2CH2CH2OH)]

2004 ◽  
Vol 59 (8) ◽  
pp. 855-858 ◽  
Author(s):  
Ekkehardt Hahn ◽  
Christoph Jocher ◽  
Thomas Lügger
Keyword(s):  
Coordination Chemistry ◽  
Structure Determination ◽  
Disodium Salt ◽  
Ferrous Chloride ◽  
Tripodal Ligand ◽  
The Core ◽  
Yellow Precipitate

AbstractThe coordination chemistry of the unsymmetric, aliphatic, tetradentate tripodal ligand N[(CH2CH2NH2)(CH2CH2OH)(CH2CH2CH2OH)] H4-1 with iron chlorides was investigated. The disodium salt of the deprotonated ligand Na2(H2-1) reacts with FeCl3 to yield a yellow precipitate which upon recrystallization from DMSO/CH2Cl2 gives red crystals of the octanuclear iron(III) complex [{FeIIICl(H2-1)}4FeIII4(μ4-O)4Cl4] 2 ・ 4CH2Cl2 containing a central Fe4(μ4-O)4 cubane core. Crystals of 2 ・4DMF were obtained by slow oxidation of the green iron(II) complex obtained from ferrous chloride and Na2(H2-1) after recrystallization from DMF. The structure determination of 2 ・4CH2Cl2 also revealed the presence of the iron(III) oxo cubane core. The core is surrounded by four iron atoms each coordinated by η4-(H2-1)2- and Cl- ligands.

scholarly journals Performance of the SoLid reactor neutrino detector

2019 ◽  
Vol 219 ◽  
pp. 08003
Author(s):  
Maja Verstraeten
Keyword(s):  
Quality Control ◽  
Energy Resolution ◽  
Neutrino Detector ◽  
Channel Response ◽  
In Situ Calibration ◽  
Reactor Neutrino ◽  
Li Isotope ◽  
Better Than

The SoLid Collaboration is currently operating a 1.6 ton neutrino detector near the Belgian BR2 reactor. Its main goal is the observation of the oscillation of electron antineutrinos to previously undetected flavour states. The highly segmented SoLid detector employs a compound scintillation technology based on PVT scintillator in combination with LiF-ZnS(Ag) screens containing the 6Li isotope. The experiment has demonstrated a channel-to-channel response that can be controlled to the level of a few percent, an energy resolution of better than 14% at 1 MeV, and a determination of the interaction vertex with a precision of 5 cm. This contribution highlights the major outcomes of the R&D program, the quality control during component manufacture and integration, the current performance and stability of the full-scale system, as well as the in-situ calibration of the detector with various radioactive sources.

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