Space storable propellant vacuum performance evaluation Final report

Rocket engine tests using space storable propellants and various injector configuration

Fluorine-hydrogen performance evaluation phase 2 - Space storable propellant performance demonstration Final report

Space storability performance of fluorine and hydrogen propellant

Carbon-poor stellar cores as supernova progenitors

Exploring stellar models which ignite carbon off-center (in the mass range of about 1.05 - 1.25 Msun, depending on the carbon mass fraction) we find that they may present an interesting SN I progenitor scenario, since whereas in the standard scenario runaway always takes place at the same density of about 2 X 10^9 gr/cm^3, in our case, due to the small amount of carbon ignited, we get a whole range of densities from 1 X 10^9 up to 6 X 10^9 gr/cm^3. These results could contribute in resolving the emerging recognition that at least some diversity among SNe I exists, since runaway at various central densities is expected to yield various outcomes in terms of the velocities and composition of the ejecta, which should be modeled and compared to observations.Comment: 49 pages, 20 figure

Alguns Traços Da Poesia De Lúcia Aizim

O que sobressai na poesia de Lúcia Aizim é seu ritmo singular e pessoal e ainda figurações temáticas em que o judaísmo transparece como matéria híbrida entremeada com elementos tropicais, brasileiros. Essa mescla, traçada em diferentes dimensões, erige uma poética singular, com ressonâncias diferenciadas, que denunciam o estrangeiro trazido para o corpo nacional, a atitude contemplativa voltada à tradição judaica, que se nutre, porém, da vida do dia a dia10384

Dentistry for Nigerians with special needs: an overview

There are approximately 25 million residents with disabilities in Nigeria. Social inclusion of individuals with disabilities is difficult since societal views of these persons are in terms of charity and welfare rather than functioning members of a community. While there are no national studies of the dental needs of individuals with disabilities in Nigeria, there are reports of local studies of patients with disabilities which indicate a greater incidence of management difficulties as well as the need for improved oral hygiene and restorative services. Nevertheless, a study of practitioner involvement in the care of individuals with disabilities reported limited preparation of dental students to provide service for this population. Some organizations, such as the Special Olympics Healthy Athletes Special Smiles and the Smile Train, have set up programmes, both educational and service, to address some of their oral health issues. It is recommended that there is a need to identify the availability of current dental service centers for individuals with disabilities, establish a national organization to stimulate an awareness of the varied needs of individuals with disabilities and real programs in schools to prepare dental students to care for individuals with disabilities. Examples of dental education accreditation standards in other countries are used as models for the improvement in the preparation of dental students to provide services for individuals with special needs

Estimating demand for perennial pigeon pea in Malawi using choice experiments

AbstractPerennial crops have numerous ecological and agronomic advantages over their annual counterparts. We estimate discrete choice models to evaluate farmers' preferences for perennial attributes of pigeon pea intercropped with maize in central and southern Malawi. Pigeon pea is a nitrogen-fixing leguminous crop, which has the potential to ameliorate soil fertility problems related to continuous maize cultivation, which are common in Southern Africa. Adoption of annual pigeon pea is relatively low but perennial production of pigeon pea may be more appealing to farmers due to some of the ancillary benefits associated with perenniality. We model perennial production of pigeon pea as a function of the attributes that differ between annual and perennial production: lower labor and seed requirements resulting from a single planting with multiple harvests, enhanced soil fertility and higher levels of biomass production. The primary tradeoff associated with perennial pigeon pea intercropped with maize is competition with maize in subsequent years of production. While maize yield is approximately twice as valuable to farmers as pigeon pea yield, we find positive yet heterogeneous demand for perenniality driven by soil fertility improvements and pigeon pea grain yield

dc readout experiment at the Caltech 40m prototype interferometer

The Laser Interferometer Gravitational Wave Observatory (LIGO) operates a 40m prototype interferometer on the Caltech campus. The primary mission of the prototype is to serve as an experimental testbed for upgrades to the LIGO interferometers and for gaining experience with advanced interferometric techniques, including detuned resonant sideband extraction (i.e. signal recycling) and dc readout (optical homodyne detection). The former technique will be employed in Advanced LIGO, and the latter in both Enhanced and Advanced LIGO. Using dc readout for gravitational wave signal extraction has several technical advantages, including reduced laser and oscillator noise couplings as well as reduced shot noise, when compared to the traditional rf readout technique (optical heterodyne detection) currently in use in large-scale ground-based interferometric gravitational wave detectors. The Caltech 40m laboratory is currently prototyping a dc readout system for a fully suspended interferometric gravitational wave detector. The system includes an optical filter cavity at the interferometer's output port, and the associated controls and optics to ensure that the filter cavity is optimally coupled to the interferometer. We present the results of measurements to characterize noise couplings in rf and dc readout using this system

Future policy implications of tidal energy array interactions

Tidal stream energy technology has progressed to a point where commercial exploitation of this sustainable resource is practical, but tidal physics dictates interactions between tidal farms that raise political, legal and managerial challenges that are yet to be met. Fully optimising the design of a turbine array requires its developer to know about other farms that will be built nearby in the future. Consequently future developments, even those in adjacent channels, have the potential to impact on project efficiency. Here we review the relevant physics, consider the implications for marine policy, and discuss potential solutions. Possible management paths range from minimal regulation to prioritise a free market, to strongly interventionist approaches that prioritise efficient resource use. An attractive exemplar of the latter is unitization, an approach to resource allocation widely used in the oil and gas industry. We argue that an interventionist approach is necessary if the greatest possible energy yield is to be produced for a given level of environmental impact