Structures for small scientific satellites

Structures and design for scientific satellite

A Field Range Bound for General Single-Field Inflation

We explore the consequences of a detection of primordial tensor fluctuations for general single-field models of inflation. Using the effective theory of inflation, we propose a generalization of the Lyth bound. Our bound applies to all single-field models with two-derivative kinetic terms for the scalar fluctuations and is always stronger than the corresponding bound for slow-roll models. This shows that non-trivial dynamics can't evade the Lyth bound. We also present a weaker, but completely universal bound that holds whenever the Null Energy Condition (NEC) is satisfied at horizon crossing.Comment: 16 page

When All the World\u27s a Stage: The Impact of Events on News Coverage of South Africa, 1979-1985

A time series analysis was used to investigate: (1) whether a significant increase in news coverage of South Africa occurred during the critical years of 1979-1985 ; (2) whether the geographic origin and/or sociopolitical impact of events, rather than deaths per se, caused the increase; and (3) the manner in which the increase occurred. Results indicated that two symbolic events (i.e., a series of riots in twenty-one South African townships, internal to South Africa; and the awarding of the Nobel Prize to Bishop Desmond Tutu, external to South Africa) cumulatively were responsible for a significant rise in news coverage of South Africa. The relationship of these symbolic sociopolitical events to the forces that shape short-term news headlines and long-term social change in general, including the imminent demise of apartheid in particular is discussed

Furniture Stability: A Review of Data and Testing Results

This report by Kids In Danger (KID) and Shane's Foundation focuses on tip-overs of dressers and chests. ASTM International, which has developed thousands of voluntary industry consensus technical standards, has a standard in place to test furniture stability. However, furniture on the market is not required to conform, resulting in widespread non-compliance. Additionally, these standards are too lenient and require reform, as testing protocols have remained virtually unchanged for over a decade, despite continuing injuries and deaths. Units may pass the standard, but still present a significant risk. KID advocates for a two-pronged approach to decreasing tip-over incidents:Increasing consumer awareness of the danger of furniture tip-overs and knowledge of the actions needed to keep children safe, andImproving furniture stability by strengthening standards, making those standards mandatory and enforceable and promoting changes in furniture design.KID compiled data from incidents reported to the U.S. Consumer Product Safety Commission (CPSC) by various sources and from the National Electronic Injury Surveillance System (NEISS). These include reports from January 1, 2010 to October 14, 2015. Findings of the data analysis include:Two-year-olds are the age group most affected by tip-overs, especially in regard to fatal incidents.Children age 2 to 5 accounted for 77% of total incidents.The age range of children injured is wider than the age range of children killed by tip-overs.Fatalities accounted for 12% of total incidents.Head injuries (37%) were the most common category of injury.Almost all (98.7%) of head injuries are related to a television tipping over on a child.KID conducted performance tests on a sample of 19 dressers and chests. Testing was run at the UL Furniture Center of Excellence in Holland, Michigan. UL laboratory technicians followed a testing protocol developed by KID. The protocol included tests based on the current voluntary standard for furniture stability. KID added tests that, among other things, evaluated for tip-overs when more weight was added (simulating larger children), drawers were full of clothes, furniture was placed on carpeting as opposed to bare flooring, televisions were placed on top of the furniture, and additional drawers were opened simultaneous with weighting one drawer. These additional tests were intended to be more representative of real-world scenarios.Test results include:Only nine of the 19 units passed performance tests based on the current tip-over safety standard, ASTM F2057.Only two units passed all tests, including the additional testing protocols added by KID.The weight of a television or any type placed on top of the unit did not decrease the stability of furniture.Furniture placed on carpet is less stable than furniture placed on hard floors.Many units remained stable when more than 70 pounds was placed on an open drawer, while others tipped with less than half that weight

Ageing in disordered magnets and local scale-invariance

The ageing of the bond-disordered two-dimensional Ising model quenched to below its critical point is studied through the two-time autocorrelator and thermoremanent magnetization (TRM). The corresponding ageing exponents are determined. The form of the scaling function of the TRM is well described by the theory of local scale-invariance.Comment: Latex2e, with epl macros, 7 pages, final for

On the predictive power of Local Scale Invariance

Local Scale Invariance (LSI) is a theory for anisotropic critical phenomena designed in the spirit of conformal invariance. For a given representation of its generators it makes non-trivial predictions about the form of universal scaling functions. In the past decade several representations have been identified and the corresponding predictions were confirmed for various anisotropic critical systems. Such tests are usually based on a comparison of two-point quantities such as autocorrelation and response functions. The present work highlights a potential problem of the theory in the sense that it may predict any type of two-point function. More specifically, it is argued that for a given two-point correlator it is possible to construct a representation of the generators which exactly reproduces this particular correlator. This observation calls for a critical examination of the predictive content of the theory.Comment: 17 pages, 2 eps figure

Kinetics of the long-range spherical model

The kinetic spherical model with long-range interactions is studied after a quench to $T < T_c$ or to $T = T_c$. For the two-time response and correlation functions of the order-parameter as well as for composite fields such as the energy density, the ageing exponents and the corresponding scaling functions are derived. The results are compared to the predictions which follow from local scale-invariance.Comment: added "fluctuation-dissipation ratios"; fixed typo