The environmental control and life-support system for a lunar base: What drives its design

The purpose of this paper is to identify and briefly discuss some of the ground rules and mission scenario details that become drivers of the environmental control and life support (ECLS) system design and of the logistics related to the design. This paper is written for mission planners and non-ECLS system engineers to inform them of the details that will be important to the ECLS engineer when the design phase is reached. In addition, examples illustrate the impact of some selected mission characteristics on the logistics associated with ECLS systems. The last section of this paper focuses on the ECLS system technology development sequence and highlights specific portions that need emphasis

Acoustic, psychophysical, and neuroimaging measurements of the effectiveness of active cancellation during auditory functional magnetic resonance imaging

Functional magnetic resonance imaging (fMRI) is one of the principal neuroimaging techniques for studying human audition, but it generates an intense background sound which hinders listening performance and confounds measures of the auditory response. This paper reports the perceptual effects of an active noise control (ANC) system that operates in the electromagnetically hostile and physically compact neuroimaging environment to provide significant noise reduction, without interfering with image quality. Cancellation was first evaluated at 600 Hz, corresponding to the dominant peak in the power spectrum of the background sound and at which cancellation is maximally effective. Microphone measurements at the ear demonstrated 35 dB of acoustic attenuation [from 93 to 58 dB sound pressure level (SPL)], while masked detection thresholds improved by 20 dB (from 74 to 54 dB SPL). Considerable perceptual benefits were also obtained across other frequencies, including those corresponding to dips in the spectrum of the background sound. Cancellation also improved the statistical detection of sound-related cortical activation, especially for sounds presented at low intensities. These results confirm that ANC offers substantial benefits for fMRI research

The Charitable Status of Nonprofit Hospitals: Toward a Donative Theory of Tax Exemption

This Article examines the growing controversy over the multi-billion dollar charitable tax exemption enjoyed by nonprofit hospitals. It begins by articulating four criteria for evaluating a rationale of the charitable exemption: deservedness, incorporating the elements of worth and need; proportionality; universality; and historical consistency. The Article then employs these criteria to refute three conventional explanations of why nonprofit hospitals are exempt: because health care is a per se charitable activity; because the treatment of indigent patients relieves a government burden; and because nonprofit hospitals provide community benefits. The Article also uses these criteria to refute two academic theories: Boris Bittker\u27s income measurement rationale and Henry Hansmann\u27s capital subsidy theory. This Article proposes a donative theory as an alternative rationale for the charitable exemption. The donative theory posits that charity describes an entity capable of attracting a substantial level of philanthropic support from the public at large. Donations exist where there is a combined failure of private markets and direct public funding to supply a shared public benefit at the optimally desired level. Donative institutions deserve a tax subsidy because the public\u27s support signals their worth, and the free-rider tendency that affects all giving assures the need for an additional, shadow subsidy. The Article further demonstrates that the donative theory comports with the statutory scheme and the four centuries of legal history that shape the legal concept of charity. In particular, the donative theory provides the only explanation of the tax law\u27s otherwise unjustifiable reliance on the law of charitable trusts