1,503 research outputs found
Some gamma-ray shielding measurements made at altitudes greater than 115000 feet using large Ge(Li) detectors
A series of balloon-flight experiments at altitudes greater than 115,000 feet were conducted to gain information relative to the use of composite shields (passive and/or active) for shielding large-volume, lithium-drifted, germanium (Ge(Li)) detectors used in gamma-ray spectrometers. Data showing the pulse-height spectra of the environmental gamma radiation as measured at 5.3 and 3.8 gms sq cm residual atmosphere with an unshielded diode detector are also presented
Re-evaluating phoneme frequencies
Causal processes can give rise to distinctive distributions in the linguistic
variables that they affect. Consequently, a secure understanding of a
variable's distribution can hold a key to understanding the forces that have
causally shaped it. A storied distribution in linguistics has been Zipf's law,
a kind of power law. In the wake of a major debate in the sciences around
power-law hypotheses and the unreliability of earlier methods of evaluating
them, here we re-evaluate the distributions claimed to characterize phoneme
frequencies. We infer the fit of power laws and three alternative distributions
to 166 Australian languages, using a maximum likelihood framework. We find
evidence supporting earlier results, but also nuancing them and increasing our
understanding of them. Most notably, phonemic inventories appear to have a
Zipfian-like frequency structure among their most-frequent members (though
perhaps also a lognormal structure) but a geometric (or exponential) structure
among the least-frequent. We compare these new insights the kinds of causal
processes that affect the evolution of phonemic inventories over time, and
identify a potential account for why, despite there being an important role for
phonetic substance in phonemic change, we could still expect inventories with
highly diverse phonetic content to share similar distributions of phoneme
frequencies. We conclude with priorities for future work in this promising
program of research.Comment: 29pp (3 figures, 3 tables). This article has been provisionally
accepted for publication (Frontiers in Psychology, Language Sciences).
Supplementary information, data and code available at
http://doi.org/10.5281/zenodo.388621
Heralded state preparation in a superconducting qubit
We demonstrate high-fidelity, quantum nondemolition, single-shot readout of a
superconducting flux qubit in which the pointer state distributions can be
resolved to below one part in 1000. In the weak excitation regime, continuous
measurement permits the use of heralding to ensure initialization to a fiducial
state, such as the ground state. This procedure boosts readout fidelity to
93.9% by suppressing errors due to spurious thermal population. Furthermore,
heralding potentially enables a simple, fast qubit reset protocol without
changing the system parameters to induce Purcell relaxation.Comment: 5 pages, 5 figure
Phylogenetic signal in phonotactics
Phylogenetic methods have broad potential in linguistics beyond tree
inference. Here, we show how a phylogenetic approach opens the possibility of
gaining historical insights from entirely new kinds of linguistic data--in this
instance, statistical phonotactics. We extract phonotactic data from 111
Pama-Nyungan vocabularies and apply tests for phylogenetic signal, quantifying
the degree to which the data reflect phylogenetic history. We test three
datasets: (1) binary variables recording the presence or absence of biphones
(two-segment sequences) in a lexicon (2) frequencies of transitions between
segments, and (3) frequencies of transitions between natural sound classes.
Australian languages have been characterized as having a high degree of
phonotactic homogeneity. Nevertheless, we detect phylogenetic signal in all
datasets. Phylogenetic signal is greater in finer-grained frequency data than
in binary data, and greatest in natural-class-based data. These results
demonstrate the viability of employing a new source of readily extractable data
in historical and comparative linguistics.Comment: Main text: 32 pages, 17 figures, 1 table. Supplementary Information:
17 pages, 1 figure. Code and data available at
http://doi.org/10.5281/zenodo.3936353. This article is in review but not yet
accepted for publication in a journa
Benchmarking and analysis of the SRC-6E reconfigurable computing system
This thesis evaluates the usefulness of the SRC-6E reconfigurable computing system for a radar signal processing application and documents the process of creating and importing VHDL code to configure the user definable logic on the SRC-6E. A false-target radar-imaging algorithm was chosen and implemented on the SRC-6E. Data from alternative computational approaches to the same problem are compared to determine the effectiveness of SRC-6E solution. The results show that the implementation of the algorithm does not provide an effective solution when executed on the SRC-6E. An evaluation of the SRC-6E difficulty of use is conducted, including a discussion of required skills, experience and development times. The algorithm test code and collected data are included as appendices.http://archive.org/details/benchmarkingndna109456170Lieutenant, United States Naval ReserveApproved for public release; distribution is unlimited
Differential Fasting Plasma Glucose and Ketone Body Levels in GHRKO versus 3xTg-AD Mice: A Potential Contributor to Aging-Related Cognitive Status?
Cognitive function declines with age and appears to correlate with decreased cerebral metabolic rate (CMR). Caloric restriction, an antiaging manipulation that extends life-span and can preserve cognitive function, is associated with decreased glucose uptake, decreased lactate levels, and increased ketone body (KB) levels in the brain. Since the majority of brain nutrients come from the periphery, this study examined whether the capacity to regulate peripheral glucose levels and KB production differs in animals with successful cognitive aging (growth hormone receptor knockouts, GHRKOs) versus unsuccessful cognitive aging (the 3xTg-AD mouse model of Alzheimer\u27s disease). Animals were fasted for 5 hours with their plasma glucose and KB levels subsequently measured. Intriguingly, in GHRKO mice, compared to those in controls, fasting plasma glucose levels were significantly decreased while their KB levels were significantly increased. Conversely, 3xTg-AD mice, compared to controls, exhibited significantly elevated plasma glucose levels and significantly reduced plasma KB levels. Taken together, these results suggest that the capacity to provide the brain with KBs versus glucose throughout an animal\u27s life could somehow help preserve cognitive function with age, potentially through minimizing overall brain exposure to reactive oxygen species and advanced glycation end products and improving mitochondrial function
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