4,915 research outputs found
Do Children from Welfare Families Obtain Less Education?
This study estimates the relationship between parental welfare receipt and children’s adulthood educational attainment. Data come from the Panel Study of Income Dynamics. Cross-sectional regression results confirm findings from previous studies that greater parental welfare receipt is significantly associated with children’s poorer educational attainment. Fixed-effect regressions indicate that the relationship between parental welfare receipt and children’s educational outcomes becomes weaker after controlling for unobserved family characteristics, but they do not eliminate the negative relationship. The relationship between parental welfare receipt and children’s educational attainment is not uniform across childhood stages. Additional analyses suggest that parental welfare receipt is not negatively related to educational attainment if combined with at least quarter-time work by the mother.
Development of blood meal protein thermoplastic
Polymers are blended with other polymers to combine their properties or improve physical characteristics and blending turns to be the most reliable techniques compare to synthesis of chemically new polymers. In the research of sustainable materials from non-potential food sources, bloodmeal is one of the best candidates for bioplastic manufacture. It is one of the highest non-synthetic sources of nitrogen coming from meat processing and approximately 80000 tonnes of raw blood is collected annually in New Zealand. Natural polymers often present processing difficulties as well as maintaining product quality over extended periods because of their hydrophilic nature. Blending bloodmeal with other polymers may offer a solution to this problem. However, most blends are immiscible, and the processing are challenging because of dissimilar nature of natural and synthetic polymer, thus requiring compatibilization to achieve good blends performance. The process to solve incompatibility is the compatibilizer should migrate to the interface, reducing the interfacial tension, stabilizing the blend morphology and improving the adhesion between phases in solid state, hence improving the mechanical properties. True thermodynamic term of miscibility of polymer blends is a mixture containing two or more components that form one phase system but this determination of miscibility may be rather ambiguous. In practice, polymer blend compositions is said compatible if they exhibit two phases on a microscopic level but the interactions between polymer groups might be reasonable in a manner that provides useful properties of the multicoponent system. In many instances, it is desirable to have two phases present, as long as we can control the multicomponent systems which depend on their structure, polymer interactions and phase sizes. We have identified several strategies in order to improve miscibility;
1. Addition of a small quantity of a third component that is miscible with both phases
2. Addition of a copolymer whose one part is miscible with one phase and another with another phase
3. Compounding blends in the presence of chemical reactants that lead to modification of at least one macromolecular species (reactive compatibilization), resulting in generation of an in-situ desired quantity of compatibilizer.
The propose of this paper is to explore the potential of blending bloodmeal with other thermoplastic by taking account the type of polymer, type of compatibilization and processing condition in order to improve processability and mechanical properties
Blends of linear-low-density polyethylene and thermoplastic bloodmeal using maleic anhydride grafted polyethylene as compatibilizer
Linear Low-Density Polyethylene (LLDPE) was blended with Novatein Thermoplastic from bloodmeal (NTP.) The compatibilizing effect of maleic anhydride grafted polyethylene (PE-g-MAH) on mechanical, morphology thermal properties and water absorption were studied and compared with blends without compatibilizer .The amount of polyethylene added was varied between 20% to 70% with 10% of compatibilizer. An improvement in compatibility between NTP and LLDPE was evident across the entire composition range only when using compatibilizer. The tensile strength of blends decreased over that pure LLDPE, but never dropped below that of pure NTP. Results showed that blending NTP with LLDPE decreased water absorption significantly, even more so using a compatibilizer. The result is a more water stable material
Unusual persistence of superconductivity against high magnetic fields in the strongly-correlated iron-chalcogenide film FeTe:O
We report an unusual persistence of superconductivity against high magnetic
fields in the iron chalcogenide film FeTe:O below ~ 2.5 K. Instead of
saturating like a mean-field behavior with a single order parameter, the
measured low-temperature upper critical field increases progressively,
suggesting a large supply of superconducting states accessible via magnetic
field or low-energy thermal fluctuations. We demonstrate that superconducting
states of finite momenta can be realized within the conventional theory,
despite its questionable applicability. Our findings reveal a fundamental
characteristic of superconductivity and electronic structure in the
strongly-correlated iron-based superconductors.Comment: 10 pages, 3 figure
An Algorithmic Framework for Multiobjective Optimization
Multiobjective (MO) optimization is an emerging field which is increasingly being encountered in many fields globally. Various metaheuristic techniques such as differential evolution (DE), genetic algorithm (GA), gravitational search algorithm (GSA), and particle swarm optimization (PSO) have been used in conjunction with scalarization techniques such as weighted sum approach and the normal-boundary intersection (NBI) method to solve MO problems. Nevertheless, many challenges still arise especially when dealing with problems with multiple objectives (especially in cases more than two). In addition, problems with extensive computational overhead emerge when dealing with hybrid algorithms. This paper discusses these issues by proposing an alternative framework that utilizes algorithmic concepts related to the problem structure for generating efficient and effective algorithms. This paper proposes a framework to generate new high-performance algorithms with minimal computational overhead for MO optimization
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Selective Laser Sintered CastForm™ Polystyrene with Controlled Porosity and Its Infiltration Characteristics by Red Wax
This paper focuses on the manufacture of polymer-based components with controlled
porosity using selective laser sintering (SLS) and on their infiltration characteristics by red wax.
CastFormTM Polystyrene (CF) samples with various densities were created by controlling the
laser energy density. Wax was then infiltrated into the sintered specimens at around 638C to
648C. The microstructures of the sintered specimens were examined using scanning electron
microscopy. The physical density was found to increase with increasing energy density and it
reached a maximum at energy density of 0.11 J/mm2
. The infiltration rate and mass of infiltrant
absorbed in a given time were found to increase with increasing porosity. However, none of the
specimens could be fully infiltrated and about 10 – 20 % of porosity still remained regardless of
energy density used for the sintering process. Finally, the potential applications of SLS parts with
controlled porosity will be discussed.This paper describes a project funded by the Research Grants Council on ‘Functionally
graded part fabrication based on the SLS process’.Mechanical Engineerin
Simulations of nonlinear harmonic generation by an internal wave beam incident on a pycnocline
Internal wave beams generated by oceanic tidal flows propagate upward and
interact with the increasing stratification found at the pycnocline. The
nonlinear generation of harmonic modes by internal wave beams incident on a
pycnocline has recently been demonstrated by laboratory experiments and
numerical simulations. In these previous studies, the harmonic modes were
trapped within the pycnocline because their frequencies exceeded that of the
stratified fluid below. Here, two-dimensional numerical simulations are used
to explore the effect of incidence angle on harmonic generation at a thin
pycnocline. At incidence angles less than 30 degrees (typical of oceanic
beams), the lowest harmonic mode freely radiates in the form of an internal
wave beam rather than being trapped within the pycnocline. The results
indicate that nonlinear refraction is the primary mechanism for harmonic
generation at incidence angles exceeding 30 degrees, but that interaction of
the incident and reflected beams is more important at smaller incidence
angles. The simulations are compared to weakly nonlinear theory based on
refraction at the pycnocline. The results yield good agreement for trapped
harmonics, but weakly nonlinear theory substantially underpredicts the
amplitude of the radiated harmonics
CP^n, or, entanglement illustrated
We show that many topological and geometrical properties of complex
projective space can be understood just by looking at a suitably constructed
picture. The idea is to view CP^n as a set of flat tori parametrized by the
positive octant of a round sphere. We pay particular attention to submanifolds
of constant entanglement in CP^3 and give a few new results concerning them.Comment: 28 pages, 9 figure
Early transitions and tertiary enrolment: The cumulative impact of primary and secondary effects on entering university in Germany
Our aim is to assess how the number of working class students entering German universities can effectively be increased. Therefore, we estimate the proportion of students from the working class that would successfully enter university if certain policy interventions were in place to eliminate primary effects (performance differentials between social classes) and/or secondary effects (choice differentials net of performance) at different transition points. We extend previous research by analysing the sequence of transitions between elementary school enrolment and university enrolment and by accounting for the impact that manipulations at earlier transitions have on the performance distribution and size of the student ‘risk-set’ at subsequent transitions. To this end, we develop a novel simulation procedure which also seeks to find viable solutions to the shortcomings in the German data landscape. Our findings show that interventions are most effective if they take place early in the educational career. Neutralizing secondary effects at the transition to upper secondary school proves to be the single most effective means to increase participation rates in tertiary education among working class students. However, this comes at the expense of lower average performance levels. (DIPF/author
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