Method and apparatus for receiving and tracking phase modulated signals

An apparatus and technique are described for receiving and tracking analog or digital phase modulated signals from 0 deg to 360 deg phase shift. In order to track a signal with many phases, a detector discerns the phase modulation of the incoming signal and a phase shifter generates a negative phase shift opposite in angle to the detected phase angle. This produces a converted series sideband component barrier signal. The residual carrier signal and the converted series sideband component carrier are added together to produce a tracking carrier signal. The tracking carrier signal is multiplied with the output from a voltage controlled oscillator in the tracking loop to obtain an error signal which drives the voltage controlled oscillator and tracks the incoming signal frequency. The technique is less susceptible to carrier interference which may degrade tracking and tracking may be performed at lower signal to noise ratios and for lower input signal power levels

Shuttle payload S-band communications system

The Shuttle payload S-band communications system design, operational capabilities, and performance are described in detail. System design requirements, overall system and configuration and operation, and laboratory/flight test results are presented. Payload communications requirements development is discussed in terms of evolvement of requirements as well as the resulting technical challenges encountered in meeting the initial requirements. Initial design approaches are described along with cost-saving initiatives that subsequently had to be made. The resulting system implementation that was finally adopted is presented along with a functional description of the system operation. A description of system test results, problems encountered, how the problems were solved, and the system flight experience to date is presented. Finally, a summary of the advancements made and the lessons learned is discussed

Renormalisation Flow and Universality for Ultracold Fermionic Atoms

A functional renormalisation group study for the BEC-BCS crossover for ultracold gases of fermionic atoms is presented. We discuss the fixed point which is at the origin of universality for broad Feshbach resonances. All macroscopic quantities depend only on one relevant parameter, the concentration a k_F, besides their dependence on the temperature in units of the Fermi energy. In particular, we compute the universal ratio between molecular and atomic scattering length in vacuum. We also present an estimate to which level of accuracy universality holds for gases of Li and K atoms.Comment: 19 pages, 3 figures, to be published in PR

Flow Equations for the BCS-BEC Crossover

The functional renormalisation group is used for the BCS-BEC crossover in gases of ultracold fermionic atoms. In a simple truncation, we see how universality and an effective theory with composite bosonic di-atom states emerge. We obtain a unified picture of the whole phase diagram. The flow reflects different effective physics at different scales. In the BEC limit as well as near the critical temperature, it describes an interacting bosonic theory.Comment: 4 pages, 4 figure

Charged amino acids may promote coronavirus SARS-CoV-2 fusion with the host ce

The charged amino acids in the spike protein of SARS-CoV-2 exhibit some specific distribution. In the RBD region of the S1 unit the positive charge dominates in the protein interior and the negative charge prevails on the surface exposed towards ACE2 receptor. The charged amino acids in the S2 region preceding heptad repeats of the spike protein of SARS-CoV-2, exhibit a central concentration, and the imbalance of a positive charge. The idea that both distributions of charged amino acids may, in an electrostatic manner, facilitate the coronavirus infection of the cell is presented. An evaluation of the virus-receptor binding energy, by docking the peptide resembling the human receptor site to the virus RBD, and the estimation of electromechanical deformation of the cell membrane by S2 during the prefusion process were included. Possible prevention of viral infection is suggested

Towards Functional Flows for Hierarchical Models

The recursion relations of hierarchical models are studied and contrasted with functional renormalisation group equations in corresponding approximations. The formalisms are compared quantitatively for the Ising universality class, where the spectrum of universal eigenvalues at criticality is studied. A significant correlation amongst scaling exponents is pointed out and analysed in view of an underlying optimisation. Functional flows are provided which match with high accuracy all known scaling exponents from Dyson's hierarchical model for discrete block-spin transformations. Implications of the results are discussed.Comment: 17 pages, 4 figures; wording sharpened, typos removed, reference added; to appear with PR

The Smooth Evolution of the Universal Genetic Code. Main Episodes

The possible scenario of the origin and evolution of genetic code is proposed, being primarily implicated by the working hypothesis which states that the chronological order of amino acids evolutionary implementation monotonically correlates with their increasing mass. It fulfills the minimalistic claim of the smallest changes of the evolving system at increasing complexity, hereinafter called "the smooth evolution". The working hypothesis was postulated concerning the results of statistical analysis indicating a strong correlation between amino acid mass and the chosen parameters of contemporary genetic code, which are expected to change in a certain individual direction during the evolution of the initial genetic system. It was additionally supplemented by the most common hypotheses adopted from the literature, as stereochemical, 'frozen accident' and coevolutional. The developed scenario allows a detailed description of the twenty-two consecutive episodes of the history of code definition and the estimation of its dynamics. It reveals the main eras of evolution conditioned by the environmental and structural constraints. It also lets the estimation of the evolutionary frequencies of codon sense expansion, and redefinition. Dominating trends and amino acids were indicated. The underlying assumptions, limits, exceptions, and the future of the code evolution have been discusse

Mucosal immune responses following intestinal nematode infection.

In most natural environments, the large majority of mammals harbour parasitic helminths that often live as adults within the intestine for prolonged periods (1-2 years). Although these organisms have been eradicated to a large extent within westernized human populations, those living within rural areas of developing countries continue to suffer from high infection rates. Indeed, recent estimates indicate that approximately 2.5 billion people worldwide, mainly children, currently suffer from infection with intestinal helminths (also known as geohelminths and soil-transmitted helminths) . Paradoxically, the eradication of helminths is thought to contribute to the increased incidence of autoimmune diseases and allergy observed in developed countries. In this review, we will summarize our current understanding of host-helminth interactions at the mucosal surface that result in parasite expulsion or permit the establishment of chronic infections with luminal dwelling adult worms. We will also provide insight into the adaptive immune mechanisms that provide immune protection against re-infection with helminth larvae, a process that is likely to be key to the future development of successful vaccination strategies. Lastly, the contribution of helminths to immune modulation and particularly to the treatment of allergy and inflammatory bowel disease will be discussed

Standard Model with Cosmologically Broken Quantum Scale Invariance

We argue that scale invariance is not anomalous in quantum field theory, provided it is broken cosmologically. We consider a locally scale invariant extension of the Standard Model of particle physics and argue that it fits both the particle and cosmological observations. The model is scale invariant both classically and quantum mechanically. The scale invariance is broken cosmologically producing all the dimensionful parameters. The cosmological constant or dark energy is a prediction of the theory and can be calculated systematically order by order in perturbation theory. It is expected to be finite at all orders. The model does not suffer from the hierarchy problem due to absence of scalar particles, including the Higgs, from the physical spectrum.Comment: 13 pages, no figures significant revisions, no change in results or conclusion