5,190 research outputs found
Peculiar Velocity and Deaberration of the Sky
Recent studies have found the earth's peculiar velocity to be significant in
microwave background based tests for compact cosmic topology, and modifications
to these tests have been proposed. Tests of non-gaussianity, weak lensing
analysis and new tests using improved CMB data will also be sensitive to
peculiar velocity. We propose here to simplify matters by showing how to
construct a deaberrated CMB map to which any test requiring a Hubble flow
viewpoint can be applied without further complication. In a similar manner
deaberration can also be applied to object surveys used for example in
topological searches and matter distribution analysis. In particular we have
produced a revised list of objects with z > 1.0 using the NASA/IPAC
Extragalactic Database.Comment: 8 pages, 1 figure, v4 accepted by Ap
An Axisymmetric Object-Based Search for a Flat Compact Dimension
A method is presented to search for a hypertorus symmetry axis by the
alignment of distant objects. This offers greater sensitivity than previously
proposed object-based methods that rely on accurate true distances. When
applied to the catalog of objects with z > 1, we find no evidence for a compact
dimension. We deduce a lower limit to the compact dimension size D > 0.9 of the
distance to the cosmic horizon. This is consistent with independent constraints
from the recent analysis of the WMAP microwave background data.Comment: 12 pages, 10 figures, minor revision, accepted by JCA
Blood lactate clearance during active recovery after an intense running bout depends on the intensity of the active recovery
High-intensity exercise training contributes to the production and accumulation of blood lactate, which is cleared by active recovery. However, there is no commonly agreed intensity or mode for clearing accumulated blood lactate. We studied clearance of accumulated blood lactate during recovery at various exercise intensities at or below the lactate threshold after high-intensity interval runs that prompted lactate accumulation. Ten males repeated 5-min running bouts at 90% of maximal oxygen uptake ([Vdot]O2max), which increased blood lactate concentration from 1.0 ± 0.1 to 3.9 ± 0.3 mmol · l-1. This was followed by recovery exercises ranging from 0 to 100% of lactate threshold. Repeated blood lactate measurements showed faster clearance of lactate during active versus passive recovery, and that the decrease in lactate was more rapid during higher (60-100% of lactate threshold) than lower (0-40% of lactate threshold) (P < 0.05) intensities. The more detailed curve and rate analyses showed that active recovery at 80-100% of lactate threshold had shorter time constants for 67% lactate clearance and higher peak clearance rates than 40% of lactate threshold or passive recovery (P < 0.05). Finally, examination of self-regulated intensities showed enhanced lactate clearance during higher versus lower intensities, further validating the intensity dependence of clearance of accumulated blood lactate. Therefore, active recovery after strenuous exercise clears accumulated blood lactate faster than passive recovery in an intensity-dependent manner. Maximum clearance occurred at active recovery close to the lactate threshold
Spectrophone stabilized laser with line center offset frequency control
Continuous offset tuning of a frequency stabilized CW gas laser is achieved by using a spectrophone filled with the same gas as the laser for sensing a dither modulation, detecting a first or second derivative of the spectrophone output with a lock-in amplifier, the detected output of which is integrated, and applying the integrator output as a correction signal through a circuit which adds to the dither signal from an oscillator a dc offset that is adjusted with a potentiometer to a frequency offset from the absorption line center of the gas, but within the spectral linewidth of the gas. Tuning about that offset frequency is achieved by adding a dc value to the detected output of the dither modulation before integration using a potentiometer
Is One Hyperparameter Optimizer Enough?
Hyperparameter tuning is the black art of automatically finding a good
combination of control parameters for a data miner. While widely applied in
empirical Software Engineering, there has not been much discussion on which
hyperparameter tuner is best for software analytics. To address this gap in the
literature, this paper applied a range of hyperparameter optimizers (grid
search, random search, differential evolution, and Bayesian optimization) to
defect prediction problem. Surprisingly, no hyperparameter optimizer was
observed to be `best' and, for one of the two evaluation measures studied here
(F-measure), hyperparameter optimization, in 50\% cases, was no better than
using default configurations.
We conclude that hyperparameter optimization is more nuanced than previously
believed. While such optimization can certainly lead to large improvements in
the performance of classifiers used in software analytics, it remains to be
seen which specific optimizers should be applied to a new dataset.Comment: 7 pages, 2 columns, accepted for SWAN1
Notes on Nyctimystes (Anura: Hylidae) treefrogs of New Guinea, with descriptions of four new species
Published: 31 January 2014Based on six common characters, 15 species of Nytimystes are segregated as the Nyctimystes cheesmanae group, but without implying monophyly. Four of them are herein described as new species. The diagnostic features of each new species are described and the male advertisement calls of six other species are compared. Other known populations are also described but are not allocated to any species, as the information about them is deficient. Some notes on previously described species are included.James I. Menzie
Notes on tree frogs, Nyctimystes species (Anura: Hylidae) of New Guinea; the Nyctimystes papua species group
Published: 20 December 2014The definition of the Nyctimystes papua Species Group, as created by Zweifel (1983), is further elaborated and the differences between N. papua and N. disruptus, including morphology and geography, are discussed. The possibility that Nyctimystes disruptus, as currently recognised, includes more than one species, with either green or brown eyes, is also investigated. The diagnostics of Nyctimystes oktediensis are reviewed leading to the conclusion that it is not distinct from N. disruptus.James I. Menzie
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