4,553 research outputs found
Preliminary results of geologic and remote sensing studies of Rima Mozart
In order to better understand the processes responsible for the formation of lunar sinuous rilles, a study of Rima Mozart was conducted using a variety of geologic, photographic, and remote sensing data. The apparent source of this rille is located in a highlands unit of known composition and it is hypothesized that thermal and mechanical erosion played an important role in the formation of Rima Mozart. Excellent photographic, topographic, multispectral, and radar data exist for this rille. The preliminary results of an analysis of this data are presented. Photographic data indicates the presence of two volcanic source vents for Rima Mozart: Kathleen and Ann. It is suggested that Rima Mozart, like many other lunar sinuous rilles, was most likely formed by a combination of events. Rima Mozart does follow a pre-existing, dominant NW/SE structural trend suggesting the influence of structural features on the rille, however, the tectonic influence is not the sole source for the formation of the rille, as suggested by the presence of the two source vents and the spatter around Ann. It is suggested that the rille formation began with an explosive eruption at Kathleen which later calmed down to a pulsating, high volume, low-viscosity lava flow. The rapid effusion rate of the magma as well as its high temperature and turbid nature helped carve the sinuous rille into the fractured and structurally weak Apennine Bench Formation underneath. Similar eruptions and subsequent flows were also created at Ann and joined to the main channel by a NE-trending secondary rille
A Ground-based Search for Lunar Resources Using High-resolution Imaging in the Infrared
When humans return to the Moon, lunar resources will play an important role in the successful deployment and maintenance of the lunar base. Previous studies have illustrated the abundance of resource materials available on the surface of the Moon, as well as their ready accessibility. Particularly worth considering are the lunar regional (2,000-30,000 sq km) pyroclastic deposits scattered about the lunar nearside. These 30-50-m-thick deposits are composed of fine-grained unconsolidated titanium- and iron-rich mafic glasses and may be used as bulk feedstock for the beneficiation of oxygen, iron, titanium, sulfur, and other solar wind gases, or simply used as is for construction and shielding purposes. A groundbased observing survey of the resource-rich regions on the lunar nearside using a new imaging technique designed to obtain much higher resolution images, and more precise compositional analyses than previously obtainable is proposed
Tracking autophagy during proliferation and differentiation of trypanosoma brucei
Autophagy is a lysosome-dependent degradation mechanism that sequesters target cargo into autophagosomal vesicles. The Trypanosoma brucei genome contains apparent orthologues of several autophagy-related proteins including an ATG8 family. These ubiquitin-like proteins are required for autophagosome membrane formation, but our studies show that ATG8.3 is atypical. To investigate the function of other ATG proteins, RNAi compatible T. brucei were modified to function as autophagy reporter lines by expressing only either YFP-ATG8.1 or YFP-ATG8.2. In the insect procyclic lifecycle stage, independent RNAi down-regulation of ATG3 or ATG7 generated autophagy-defective mutants and confirmed a pro-survival role for autophagy in the procyclic form nutrient starvation response. Similarly, RNAi depletion of ATG5 or ATG7 in the bloodstream form disrupted autophagy, but did not impede proliferation. Further characterisation showed bloodstream form autophagy mutants retain the capacity to undergo the complex cellular remodelling that occurs during differentiation to the procyclic form and are equally susceptible to dihydroxyacetone-induced cell death as wild type parasites, not supporting a role for autophagy in this cell death mechanism. The RNAi reporter system developed, which also identified TOR1 as a negative regulator controlling YFP-ATG8.2 but not YFP-ATG8.1 autophagosome formation, will enable further targeted analysis of the mechanisms and function of autophagy in the medically relevant bloodstream form of T. brucei
The Concepts of Reliability and Homogeneity
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67956/2/10.1177_001316445001000103.pd
Preliminary results of spectral reflectance studies of tycho crater
The preliminary analysis and interpretation of near infrared spectra obtained for both the interior and exterior deposits associated with the Tycho crater is presented. Specific objectives were: (1) to determine the composition and stratigraphy of the highland crust in the Tycho target site; (2) to determine the likely composition of the primary ejecta which may be present in ray deposits; (3) to investigate the nature of spectral units defined in previous studies; (4) to further investigate the nature and origin of both the bright and dark haloes around the rim crest; and (5) to compare the compositions determined for the Tycho units with those of the Aristarchus crater as well as typical highland deposits. The spectra obtained for the interior areas exhibit similar spectral features. These include relatively strong 1 micron absorption bands whose minima are centered between 0.97 and 0.99 microns and shallow to intermediate continuum slopes. The spectra generally exhibit indications of a 1.3 micron feature consistent with the presence of Fe(2+) bearing plagioclase feldspar. The strong 1 micron absorption features indicate a dominant high Ca clinopyroxene component. Results obtained from the ejecta deposits show that the spectrum of the inner, bright halo is almost identical with those obtained for interior units. The spectrum of the dark halo exhibits a wide, relatively shallow absorption feature centered at 1.01 microns, a 1.3 micron absorption, and a steep continuum slope. This spectrum is interpreted as indicating the presence of pyroxene, Fe-bearing feldspar, and a significant component of Fe-bearing impact melt glass. Finally, the spectra of spots inside Tycho show similarity with certain spectra for Aristarchus. However, the suite of spectra obtained for Tycho exhibits a different trend in terms of band center versus width
Stiffness and energy losses in cylindrically symmetric superconductor levitating systems
Stiffness and hysteretic energy losses are calculated for a magnetically
levitating system composed of a type-II superconductor and a permanent magnet
when a small vibration is produced in the system. We consider a cylindrically
symmetric configuration with only vertical movements and calculate the current
profiles under the assumption of the critical state model. The calculations,
based on magnetic energy minimization, take into account the demagnetization
fields inside the superconductor and the actual shape of the applied field. The
dependence of stiffness and hysteretic energy losses upon the different
important parameters of the system such as the superconductor aspect ratio, the
relative size of the superconductor-permanent magnet, and the critical current
of the superconductor are all systematically studied. Finally, in view of the
results, we provide some trends on how a system such as the one studied here
could be designed in order to optimize both the stiffness and the hysteretic
losses.Comment: 8 pages; 8 figure
Remote sensing and geologic studies of the terrain northwest of Humorum basin
A portion of the highlands terrain northwest of the Humorum basin, a large multiringed impact structure on the southwestern portion of the lunar nearside, exhibits anomalous characteristics in several remote sensing data sets. A variety of remote sensing studies of the terrain northwest of Humorum basin were performed in order to determine the composition and origin of the anomalous unit as well as the composition of the highland material exposed by the Humorum impact event. It was found that at least a portion of the mare-bounding ring of Humorum is composed of pure anorthosite. Other details of the study are reported
The Reliability of Test Discriminations
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66658/2/10.1177_001316445501500404.pd
Intergenerational equity in municipal accounting: New Zealand 1910s
Accounting for fixed assets by municipalities has been discussed in the accounting history literature previously. This paper addresses two issues related to accounting for fixed assets not previously discussed; the influence of the principle of intergenerational equity on local government accounting, and the influence of users of accounting information in accounting policy making in government accounting. The paper identifies that users of accounting information have had significant influence in a debate on government accounting policy, and that the principle of intergenerational equity was given a position of high importance in the debate, but not an unchallengeable position. The motivation of the users of accounting information to engage in the debates is identified as a form of civic duty, which is consistent with the ethical imperative in ensuring intergenerational equity
The Affective Impact of Financial Skewness on Neural Activity and Choice
Few finance theories consider the influence of “skewness” (or large and asymmetric but unlikely outcomes) on financial choice. We investigated the impact of skewed gambles on subjects' neural activity, self-reported affective responses, and subsequent preferences using functional magnetic resonance imaging (FMRI). Neurally, skewed gambles elicited more anterior insula activation than symmetric gambles equated for expected value and variance, and positively skewed gambles also specifically elicited more nucleus accumbens (NAcc) activation than negatively skewed gambles. Affectively, positively skewed gambles elicited more positive arousal and negatively skewed gambles elicited more negative arousal than symmetric gambles equated for expected value and variance. Subjects also preferred positively skewed gambles more, but negatively skewed gambles less than symmetric gambles of equal expected value. Individual differences in both NAcc activity and positive arousal predicted preferences for positively skewed gambles. These findings support an anticipatory affect account in which statistical properties of gambles—including skewness—can influence neural activity, affective responses, and ultimately, choice
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