Apparatus and method for stabilized phase detection for binary signal tracking loops

Apparatus and method is presented for phase detection in binary signal tracking loops wherein two bandpass detectors are alternately interchanged between electrical connection with two local code reference tracking signals in order to cancel any adverse effect of gain imbalance in the bandpass detectors and direct current offset or drift. The detectors are time shared in multiplex fashion between the two local reference signals

Differential phase shift keyed signal resolver

A differential phase shift keyed signal resolver resolves the differential phase shift in the incoming signal to determine the data content thereof overcoming phase uncertainty without requiring a transmitted reference signal

Four-phase differential phase shift resolver

Two systems have been developed to resolve phase uncertainty without transmitting reference signals. In both methods signal is impressed on carrier as differential, rather than absolute, phase shift. At the receiver four-phase demodulation and logic process unambiguously resolves differential phase shift of input carrier

Differential phase shift keyed communication system

A communication system using differential phase-shift-keying (DPSK) transmits and receives binary data without requiring timing or phase reference signals. The system encodes and modulates the data at the transmitter, and decodes and demodulates the data at the receiver, without ambiguity as to the data content

Design and breadboard evaluation of the SPS reference phase control system concept

The total breadboard system includes one pilot transmitter, one pilot receiver, nine phase distribution units, and two power transponders. With this complement of equipment, segments of a typical phase distribution system can be assembled to facilitate the evaluation of significant system parameters. The achievable accuracy of a large phase distribution system, the sensitivity of the system to parameter variations, and the limitations of commercially available components in such applications were determined

The star formation history of damped Lyman alpha absorbers

The local power law relationship between the surface densities of neutral hydrogen gas and star formation rate (SFR) can be used to explore the SFR properties of damped Lyman alpha (DLA) systems at higher redshift. We find that while the SFR densities for DLA systems are consistent with luminous star forming galaxies at redshifts below z~0.6, at higher redshifts their SFR density is too low for them to provide a significant contribution to the cosmic star formation history (SFH). This suggests that the majority of DLAs may be a distinct population from the Lyman break galaxies (LBGs) or submillimeter star-forming galaxies that together dominate the SFR density at high redshift. It is also possible that the DLAs do not trace the bulk of the neutral gas at high redshift. The metallicity properties of DLAs are consistent with this interpretation. The DLAs show a metal mass density lower by two orders of magnitude at all redshifts than that inferred from the SFH of the universe. These results are consistent with DLAs being dominated by low mass systems having low SFRs or a late onset of star formation, similar to the star formation histories of dwarf galaxies in the local universe.Comment: 9 pages, 5 figures, accepted for publication in Ap

Recent developments in classical density functional theory: Internal energy functional and diagrammatic structure of fundamental measure theory

An overview of several recent developments in density functional theory for classical inhomogeneous liquids is given. We show how Levy's constrained search method can be used to derive the variational principle that underlies density functional theory. An advantage of the method is that the Helmholtz free energy as a functional of a trial one-body density is given as an explicit expression, without reference to an external potential as is the case in the standard Mermin-Evans proof by reductio ad absurdum. We show how to generalize the approach in order to express the internal energy as a functional of the one-body density distribution and of the local entropy distribution. Here the local chemical potential and the bulk temperature play the role of Lagrange multipliers in the Euler-Lagrange equations for minimiziation of the functional. As an explicit approximation for the free-energy functional for hard sphere mixtures, the diagrammatic structure of Rosenfeld's fundamental measure density unctional is laid out. Recent extensions, based on the Kierlik-Rosinberg scalar weight functions, to binary and ternary non-additive hard sphere mixtures are described.Comment: 15 pages, 6 figure

Aggression and violence in healthcare and its impact on nursing students: A narrative review of the literature

Aggression and violence is a significant social problem in many countries and an increasing problem in healthcare settings in which nurses are particularly vulnerable. The literature suggests that aggression and violence has a significant negative impact upon nurses and potentially upon nursing students and can result in these staff members experiencing stress as a direct result of these adverse events. The literature suggests that there is confusion over what constitutes aggression and violence in the workplace and therefore a true lack of understanding of the scale of the problem relating to nursing students. This review proposes that nursing students are indeed at significant risk of aggression and violence in the clinical setting which has the potential to significantly impact their role as a novice carer. Furthermore, aggression and violence can manifest negative stress responses in individuals, therefore, the potential for nursing students to cope with stressful situations shall be presented

Numerical Problems in Coupling Photon Momentum (Radiation Pressure) to Gas

Radiation pressure (RP; or photon momentum absorbed by gas) is important in a tremendous range of astrophysical systems. But we show the usual method for assigning absorbed photon momentum to gas in numerical radiation-hydrodynamics simulations (integrating over cell volumes or evaluating at cell centers) can severely under-estimate the RP force in the immediate vicinity around un-resolved (point/discrete) sources (and subsequently under-estimate its effects on bulk gas properties), unless photon mean-free-paths are highly-resolved in the fluid grid. The existence of this error is independent of the numerical radiation transfer (RT) method (even in exact ray-tracing/Monte-Carlo methods), because it depends on how the RT solution is interpolated back onto fluid elements. Brute-force convergence (resolving mean-free paths) is impossible in many cases (especially where UV/ionizing photons are involved). Instead, we show a 'face-integrated' method -- integrating and applying the momentum fluxes at interfaces between fluid elements -- better approximates the correct solution at all resolution levels. The 'fix' is simple and we provide example implementations for ray-tracing, Monte-Carlo, and moments RT methods in both grid and mesh-free fluid schemes. We consider an example of star formation in a molecular cloud with UV/ionizing RP. At state-of-the-art resolution, cell-integrated methods under-estimate the net effects of RP by an order of magnitude, leading (incorrectly) to the conclusion that RP is unimportant, while face-integrated methods predict strong self-regulation of star formation and cloud destruction via RP.Comment: 9 pages, 4 figures. Updated to match accepted MNRAS versio