Distribution of Eigenvalues for the Modular Group

The two-point correlation function of energy levels for free motion on the modular domain, both with periodic and Dirichlet boundary conditions, are explicitly computed using a generalization of the Hardy-Littlewood method. It is shown that ion the limit of small separations they show an uncorrelated behaviour and agree with the Poisson distribution but they have prominent number-theoretical oscillations at larger scale. The results agree well with numerical simulations.Comment: 72 pages, Latex, the fiogures mentioned in the text are not vital, but can be obtained upon request from the first Autho

Quantum mechanics: Myths and facts

A common understanding of quantum mechanics (QM) among students and practical users is often plagued by a number of "myths", that is, widely accepted claims on which there is not really a general consensus among experts in foundations of QM. These myths include wave-particle duality, time-energy uncertainty relation, fundamental randomness, the absence of measurement-independent reality, locality of QM, nonlocality of QM, the existence of well-defined relativistic QM, the claims that quantum field theory (QFT) solves the problems of relativistic QM or that QFT is a theory of particles, as well as myths on black-hole entropy. The fact is that the existence of various theoretical and interpretational ambiguities underlying these myths does not yet allow us to accept them as proven facts. I review the main arguments and counterarguments lying behind these myths and conclude that QM is still a not-yet-completely-understood theory open to further fundamental research.Comment: 51 pages, pedagogic review, revised, new references, to appear in Found. Phy

Narrow genetic base in forest restoration with holm oak (Quercus ilex L.) in Sicily

In order to empirically assess the effect of actual seed sampling strategy on genetic diversity of holm oak (Quercus ilex) forestations in Sicily, we have analysed the genetic composition of two seedling lots (nursery stock and plantation) and their known natural seed origin stand by means of six nuclear microsatellite loci. Significant reduction in genetic diversity and significant difference in genetic composition of the seedling lots compared to the seed origin stand were detected. The female and the total effective number of parents were quantified by means of maternity assignment of seedlings and temporal changes in allele frequencies. Extremely low effective maternity numbers were estimated (Nfe $\approx$ 2-4) and estimates accounting for both seed and pollen donors gave also low values (Ne $\approx$ 35-50). These values can be explained by an inappropriate forestry seed harvest strategy limited to a small number of spatially close trees

A precise measurement of the magnetic field in the corona of the black hole binary V404 Cygni

Observations of binary stars containing an accreting black hole or neutron star often show x-ray emission extending to high energies (>10 kilo­–electron volts), which is ascribed to an accretion disk corona of energetic particles akin to those seen in the solar corona. Despite their ubiquity, the physical conditions in accretion disk coronae remain poorly constrained. Using simultaneous infrared, optical, x-ray, and radio observations of the Galactic black hole system V404 Cygni, showing a rapid synchrotron cooling event in its 2015 outburst, we present a precise 461 ± 12 gauss magnetic field measurement in the corona. This measurement is substantially lower than previous estimates for such systems, providing constraints on physical models of accretion physics in black hole and neutron star binary systems. This article has a correction. Please see: http://science.sciencemag.org/content/360/6386/eaat927

Energetic particle influence on the Earth's atmosphere

This manuscript gives an up-to-date and comprehensive overview of the effects of energetic particle precipitation (EPP) onto the whole atmosphere, from the lower thermosphere/mesosphere through the stratosphere and troposphere, to the surface. The paper summarizes the different sources and energies of particles, principally galactic cosmic rays (GCRs), solar energetic particles (SEPs) and energetic electron precipitation (EEP). All the proposed mechanisms by which EPP can affect the atmosphere are discussed, including chemical changes in the upper atmosphere and lower thermosphere, chemistry-dynamics feedbacks, the global electric circuit and cloud formation. The role of energetic particles in Earth’s atmosphere is a multi-disciplinary problem that requires expertise from a range of scientific backgrounds. To assist with this synergy, summary tables are provided, which are intended to evaluate the level of current knowledge of the effects of energetic particles on processes in the entire atmosphere

Whole-genome sequencing reveals host factors underlying critical COVID-19

Critical COVID-19 is caused by immune-mediated inflammatory lung injury. Host genetic variation influences the development of illness requiring critical care1 or hospitalization2,3,4 after infection with SARS-CoV-2. The GenOMICC (Genetics of Mortality in Critical Care) study enables the comparison of genomes from individuals who are critically ill with those of population controls to find underlying disease mechanisms. Here we use whole-genome sequencing in 7,491 critically ill individuals compared with 48,400 controls to discover and replicate 23 independent variants that significantly predispose to critical COVID-19. We identify 16 new independent associations, including variants within genes that are involved in interferon signalling (IL10RB and PLSCR1), leucocyte differentiation (BCL11A) and blood-type antigen secretor status (FUT2). Using transcriptome-wide association and colocalization to infer the effect of gene expression on disease severity, we find evidence that implicates multiple genes—including reduced expression of a membrane flippase (ATP11A), and increased expression of a mucin (MUC1)—in critical disease. Mendelian randomization provides evidence in support of causal roles for myeloid cell adhesion molecules (SELE, ICAM5 and CD209) and the coagulation factor F8, all of which are potentially druggable targets. Our results are broadly consistent with a multi-component model of COVID-19 pathophysiology, in which at least two distinct mechanisms can predispose to life-threatening disease: failure to control viral replication; or an enhanced tendency towards pulmonary inflammation and intravascular coagulation. We show that comparison between cases of critical illness and population controls is highly efficient for the detection of therapeutically relevant mechanisms of disease

Summary report of the turbojet test chamber acceptance tests conducted 11-12 December 1963

Acceptance testing of the Turbojet Engine Test Chamber was conducted during the week of 9 December 1963 by personnel from the U.S. Naval Post­ graduate School, Department of Aeronautics, from the Overhaul and Repair Department, NAS North Island and from the Bureau of Naval Weapons Fleet Readiness Representative--Pacific. A J-57-BB turbojet engine which had undergone major overhaul and testing at NAS North Island was utilized as the correlating powerplant for this investigation. The test data reveal satisfactory engine performance correlation between the subject chamber and the North Island facility. Sizeable discrepancies were noted in these correlating data; however, each deviation was traced to a known defect in the USNPGS test cell. All of the major system s in the facility operated satisfactorily and controllability of the jet engine was adequate . Minor rework is required on the instrumentation systerns for attaining complete control and utilization of the chamber. The aerodynamic charac­teristics of the facility appear to be excellent. The acoustic survey revealed that the Sound Pressure Levels outside of the facility were consistently exceeded when operating the engine at Military Power and above . The movement of exhaust augmenter to its most forward position accentuated the over-limit conditions. The excessive SPL values were noted in all frequency ranges from 75 cps to 10,000 cps and were observed primarily in the area in front of the test facility. Other test facility discrepancies were primarily component failures which were the result of faulty design. Examples of these defects are; the failure of the exhaust augmentor tube retaining supports, the lack of control of exhaust cooling water, the mechanical failure of the lighting fixtures in the test chamber and the excessive fuel flow indicator fluctuation s at all power settings. Correction of each discrepancy noted herein would result in the establishment of a jet engine test facility which could be utilized for the most exacting research activities

Summary report of the turboprop test chamber acceptance tests conducted on 27 April to 8 May 1964

Acceptance testing of the Turboprop Test Chamber was conducted during the weeks of 27 April and 4 May 1964. The tests were conducted by personnel from the Overhaul and Repair Department, Alameda Naval Air Station, from the Bureau of Naval Weapons Fleet Readiness Represent­ative, Pacific and from the USNPGS Department of Aeronautics. The power plant utilized for correlating purposes for a T-56-lOW turboprop engine, recently overhauled at NAS Alameda while the propeller was the Hamilton Standard model required for this engine. The test data reveal satisfactory correlation of the engine performance data with the Alameda test results. The discrepancies that do appear are the result of errors in the instrumentation system and do not present a major problem. All of the major facility systems function satisfactorily except the oil supply system and the chamber lighting fixtures. Engine starting and control systems were adequate although somewhat different from the designs utilized in the NAVWEPS specifica­tions for this engine. The engine support stand and thrust measuring assembly were found to be structurally sound and functioned satisfactorily. The propeller orifice assembly did not induce prohibitive vibrational stresses as was anticipated. However, the vibrational loads did cause the majority of the orifice retaining bolts to loosen during the test sequence. Three bolts were found beneath the test stand; these could have caused object damage to the engine. The major areas of discrepancy are the engine oil supply system and the test chamber lighting fixtures. The engine oil system as designed could not satisfy the requirements for the T-56 series engine. It was necessary to re-route the oil by-pass system, to obtain a more precise control of the engine oil supply and pressure, and to provide a method to heat the oil for operation of the engine at high power set­tings. The system as temporarily modified, did function adequately during the test period. The lighting fixtures mounted on swivel joint bases oscillated vio­lently when operating the engine at Idle power. One fixture above the engine broke loose during this short period and was blown clear of the engine stand by the propeller air stream. All ceiling-mounted light fixtures were removed from the chamber before further engine operation. The acoustic survey revealed that the acoustic paneling in the in­ let and the exhaust passages functioned satisfactorily. However, the Sound Pressure Level reduction across the chamber front double-doors did not meet the specified limits. Corrective action is required to (1) provide adequate and safe lighting in the test chamber, (2) re-design and install an oil supply system compatible for operation with the T-56 engine, and (3) provide positive locking devices on all bolted fixtures in the test chambers