Dimensional Accuracy in X-Ray Computed Tomography Imaging

X-ray computed tomography (CT) has become an important non-destructive evaluation technique. CT contributes to a wide range of nondestructive evaluation (NDE) applications [1]. These include typical NDE applications (e.g., defect detection and quality control), more advanced NDE applications (e.g., process development and model verification), and the more recent application of CT-based metrology (e.g., geometric inspection and reverse engineering). In the traditional applications of CT, the user is concerned with defect sensitivity, which is a combination of spatial resolution, contrast sensitivity and slice thickness [2]. For CT-based metrology, the term “defect sensitivity” has little meaning; dimensional accuracy of the system becomes paramount

Thermal Interface Evaluation of Heat Transfer from a Pumped Loop to Titanium-Water Thermosyphons

Titanium-water thermosyphons are being considered for use in the heat rejection system for lunar outpost fission surface power. Key to their use is heat transfer between a closed loop heat source and the heat pipe evaporators. This work describes laboratory testing of several interfaces that were evaluated for their thermal performance characteristics, in the temperature range of 350 to 400 K, utilizing a water closed loop heat source and multiple thermosyphon evaporator geometries. A gas gap calorimeter was used to measure heat flow at steady state. Thermocouples in the closed loop heat source and on the evaporator were used to measure thermal conductance. The interfaces were in two generic categories, those immersed in the water closed loop heat source and those clamped to the water closed loop heat source with differing thermal conductive agents. In general, immersed evaporators showed better overall performance than their clamped counterparts. Selected clamped evaporator geometries offered promise

Wide Angle Decentered Lens Beam Steering for Infrared Countermeasures Applications

A beam-steering system consisting of three cemented achromatic doublets is presented. Intended for use in IR countermeasure applications, our system is designed to operate over the 2- to 5-μm spectrum with minimum angular dispersion. We show that dispersion can be minimized by using doublet lenses fashioned from AMTIR-1 and germanium. Our system is designed to be compact and lightweight, with no internal foci, while allowing steering to ±22.5 deg. We also maintain a minimum 2-in. clear aperture for all steering angles, and a nominal divergence of 1 mrad. Plane wave and Gaussian beam analyses of our system are presented

A Corpus Investigation of Syntactic Embedding in Piraha

The Pirahã language has been at the center of recent debates in linguistics, in large part because it is claimed not to exhibit recursion, a purported universal of human language. Here, we present an analysis of a novel corpus of natural Pirahã speech that was originally collected by Dan Everett and Steve Sheldon. We make the corpus freely available for further research. In the corpus, Pirahã sentences have been shallowly parsed and given morpheme-aligned English translations. We use the corpus to investigate the formal complexity of Pirahã syntax by searching for evidence of syntactic embedding. In particular, we search for sentences which could be analyzed as containing center-embedding, sentential complements, adverbials, complementizers, embedded possessors, conjunction or disjunction. We do not find unambiguous evidence for recursive embedding of sentences or noun phrases in the corpus. We find that the corpus is plausibly consistent with an analysis of Pirahã as a regular language, although this is not the only plausible analysis

Cultural Differences in Perceptual Reorganization in US and Pirahã Adults

Visual illusions and other perceptual phenomena can be used as tools to uncover the otherwise hidden constructive processes that give rise to perception. Although many perceptual processes are assumed to be universal, variable susceptibility to certain illusions and perceptual effects across populations suggests a role for factors that vary culturally. One striking phenomenon is seen with two-tone images—photos reduced to two tones: black and white. Deficient recognition is observed in young children under conditions that trigger automatic recognition in adults. Here we show a similar lack of cue-triggered perceptual reorganization in the Pirahã, a hunter-gatherer tribe with limited exposure to modern visual media, suggesting such recognition is experience- and culture-specific

KPF: Keck Planet Finder

KPF is a fiber-fed, high-resolution, high-stability spectrometer in development at the UC Berkeley Space Sciences Laboratory for the W.M. Keck Observatory. The instrument is designed to characterize exoplanets via Doppler spectroscopy with a single measurement precision of 0.5ms_(-1) or better, however its resolution and stability will enable a wide variety of astrophysical pursuits. KPF will have a 200mm collimated beam diameter and a resolving power of >80,000. The design includes a green channel (440nm to 590 nm) and red channel (590nm to 850 nm). A novel design aspect of KPF is the use of a Zerodur optical bench, and Zerodur optics with integral mounts, to provide stability against thermal expansion and contraction effects

Food-based dietary guidelines for optimizing calcium intakes for reproductive-aged women in Ethiopia using local foods

© 2024 The Author(s). Annals of the New York Academy of Sciences published by Wiley Periodicals LLC on behalf of The New York Academy of Sciences.Increasing dietary calcium intakes of Ethiopian women of reproductive age (WRA) is a public health priority for reducing pre-eclampsia in pregnancy. Using linear programming, we determined whether locally available foods consumed by WRA in nine regions (urban and rural) and two administrative cities of Ethiopia could provide 1000 mg/day of dietary calcium, and we identified food-based recommendations (FBRs) to improve dietary calcium adequacy in each region. Results showed that diets providing 1000 mg/day of calcium were feasible in eight regions (40%) of the target populations examined. It would, however, require marked changes for most populations (90%), increasing the number of servings per week of several food groups to levels close to those of high consumers in each population. The selected calcium-specific FBRs integrate well into the 2022 Ethiopian Dietary Guidelines, requiring additional messages to consume green leafy vegetables, milk, root crops, or teff (Eragrostis tef) or to consume a higher number of servings of vegetables than currently recommended, depending on the population. In conclusion, these analyses show that a food-based approach can be used to achieve dietary calcium adequacy among WRA in 40% of the populations examined. For the other populations, food-based interventions alone may be inadequate and other interventions are likely needed.publishersversionepub_ahead_of_prin

The Extragalactic Distance Scale Key Project XXVII. A Derivation of the Hubble Constant Using the Fundamental Plane and Dn-Sigma Relations in Leo I, Virgo, and Fornax

Using published photometry and spectroscopy, we construct the fundamental plane and D_n-Sigma relations in Leo I, Virgo and Fornax. The published Cepheid P-L relations to spirals in these clusters fixes the relation between angular size and metric distance for both the fundamental plane and D_n-Sigma relations. Using the locally calibrated fundamental plane, we infer distances to a sample of clusters with a mean redshift of cz \approx 6000 \kms, and derive a value of H_0=78+- 5+- 9 km/s/Mpc (random, systematic) for the local expansion rate. This value includes a correction for depth effects in the Cepheid distances to the nearby clusters, which decreased the deduced value of the expansion rate by 5% +- 5%. If one further adopts the metallicity correction to the Cepheid PL relation, as derived by the Key Project, the value of the Hubble constant would decrease by a further 6%+- 4%. These two sources of systematic error, when combined with a +- 6% error due to the uncertainty in the distance to the Large Magellanic Cloud, a +- 4% error due to uncertainties in the WFPC2 calibration, and several small sources of uncertainty in the fundamental plane analysis, combine to yield a total systematic uncertainty of +- 11%. We find that the values obtained using either the CMB, or a flow-field model, for the reference frame of the distant clusters, agree to within 1%. The Dn-Sigma relation also produces similar results, as expected from the correlated nature of the two scaling relations. A complete discussion of the sources of random and systematic error in this determination of the Hubble constant is also given, in order to facilitate comparison with the other secondary indicators being used by the Key Project.Comment: 21 pages, 3 figures, Accepted for publication in Ap

Grouping in object recognition: The role of a Gestalt law in letter identification

The Gestalt psychologists reported a set of laws describing how vision groups elements to recognize objects. The Gestalt laws “prescribe for us what we are to recognize ‘as one thing’” (Köhler, 1920). Were they right? Does object recognition involve grouping? Tests of the laws of grouping have been favourable, but mostly assessed only detection, not identification, of the compound object. The grouping of elements seen in the detection experiments with lattices and “snakes in the grass” is compelling, but falls far short of the vivid everyday experience of recognizing a familiar, meaningful, named thing, which mediates the ordinary identification of an object. Thus, after nearly a century, there is hardly any evidence that grouping plays a role in ordinary object recognition. To assess grouping in object recognition, we made letters out of grating patches and measured threshold contrast for identifying these letters in visual noise as a function of perturbation of grating orientation, phase, and offset. We define a new measure, “wiggle”, to characterize the degree to which these various perturbations violate the Gestalt law of good continuation. We find that efficiency for letter identification is inversely proportional to wiggle and is wholly determined by wiggle, independent of how the wiggle was produced. Thus the effects of three different kinds of shape perturbation on letter identifiability are predicted by a single measure of goodness of continuation. This shows that letter identification obeys the Gestalt law of good continuation and may be the first confirmation of the original Gestalt claim that object recognition involves grouping

The Rule of Law is Dead! Long Live the Rule of Law!

Polls show that a significant proportion of the public considers judges to be political. This result holds whether Americans are asked about Supreme Court justices, federal judges, state judges, or judges in general. At the same time, a large majority of the public also believes that judges are fair and impartial arbiters, and this belief also applies across the board. In this paper, I consider what this half-law-half-politics understanding of the courts means for judicial legitimacy and the public confidence on which that legitimacy rests. Drawing on the Legal Realists, and particularly on the work of Thurman Arnold, I argue against the notion that the contradictory views must be resolved in order for judicial legitimacy to remain intact. A rule of law built on contending legal and political beliefs is not necessarily fair or just. But it can be stable. At least in the context of law and courts, a house divided may stand