2,724 research outputs found
An Infrasonic Missing Fundamental Rises at 18.5Hz
The Missing Fundamental (MF) phenomenon is an auditory processing artifact which arises from the perception of a harmonically-structured complex sound in the absence of the complex sound’s fundamental frequency (f0). Constructive interference occurring between constituent waveforms of the harmonic series may elicit a perceptible tone at the f0’s pitch. A related illusion, known as binaural auditory beats (BAB), may also generate nonexistent perceptible pitches through a shared mechanism. A harmonic series suggesting to an infrasonic f0 (1/f) noise and broken MF conditions. This data suggests that an infrasonic MF tone is generated, despite the normally imperceptible nature of the sound. The computational phenomenon reported here may also occur throughout the cortex, where it could influence or induce different conscious states. The practical implications of altering cortical activity is relevant in understanding processing disorders such as Attention Deficit Hyperactivity Disorder and Schizophrenia
Reproduction and Dispersal of Biological Soil Crust Organisms
Biological soil crusts (BSCs) consist of a diverse and highly integrated community of organisms that effectively colonize and collectively stabilize soil surfaces. BSCs vary in terms of soil chemistry and texture as well as the environmental parameters that combine to support unique combinations of organisms—including cyanobacteria dominated, lichen-dominated, and bryophyte-dominated crusts. The list of organismal groups that make up BSC communities in various and unique combinations include—free living, lichenized, and mycorrhizal fungi, chemoheterotrophic bacteria, cyanobacteria, diazotrophic bacteria and archaea, eukaryotic algae, and bryophytes. The various BSC organismal groups demonstrate several common characteristics including—desiccation and extreme temperature tolerance, production of various soil binding chemistries, a near exclusive dependency on asexual reproduction, a pattern of aerial dispersal over impressive distances, and a universal vulnerability to a wide range of human-related perturbations. With this publication, we provide literature-based insights as to how each organismal group contributes to the formation and maintenance of the structural and functional attributes of BSCs, how they reproduce, and how they are dispersed. We also emphasize the importance of effective application of molecular and microenvironment sampling and assessment tools in order to provide cogent and essential answers that will allow scientists and land managers to better understand and manage the biodiversity and functional relationships of soil crust communities
Statistical mechanics of dimers on quasiperiodic tilings
We study classical dimers on two-dimensional quasiperiodic Ammann-Beenker
(AB) tilings. Despite the lack of periodicity we prove that each infinite
tiling admits 'perfect matchings' in which every vertex is touched by one
dimer. We introduce an auxiliary 'AB' tiling obtained from the AB tiling by
deleting all 8-fold coordinated vertices. The AB tiling is again
two-dimensional, infinite, and quasiperiodic. The AB tiling has a single
connected component, which admits perfect matchings. We find that in all
perfect matchings, dimers on the AB tiling lie along disjoint
one-dimensional loops and ladders, separated by 'membranes', sets of edges
where dimers are absent. As a result, the dimer partition function of the
AB tiling factorizes into the product of dimer partition functions along
these structures. We compute the partition function and free energy per edge on
the AB tiling using an analytic transfer matrix approach. Returning to the
AB tiling, we find that membranes in the AB tiling become
'pseudomembranes', sets of edges which collectively host at most one dimer.
This leads to a remarkable discrete scale-invariance in the matching problem.
The structure suggests that the AB tiling should exhibit highly inhomogenous
and slowly decaying connected dimer correlations. Using Monte Carlo
simulations, we find evidence supporting this supposition in the form of
connected dimer correlations consistent with power law behaviour. Within the
set of perfect matchings we find quasiperiodic analogues to the staggered and
columnar phases observed in periodic systems.Comment: 33 pages, 26 figure
PVR: Patch-to-Volume Reconstruction for Large Area Motion Correction of Fetal MRI
In this paper we present a novel method for the correction of motion
artifacts that are present in fetal Magnetic Resonance Imaging (MRI) scans of
the whole uterus. Contrary to current slice-to-volume registration (SVR)
methods, requiring an inflexible anatomical enclosure of a single investigated
organ, the proposed patch-to-volume reconstruction (PVR) approach is able to
reconstruct a large field of view of non-rigidly deforming structures. It
relaxes rigid motion assumptions by introducing a specific amount of redundant
information that is exploited with parallelized patch-wise optimization,
super-resolution, and automatic outlier rejection. We further describe and
provide an efficient parallel implementation of PVR allowing its execution
within reasonable time on commercially available graphics processing units
(GPU), enabling its use in the clinical practice. We evaluate PVR's
computational overhead compared to standard methods and observe improved
reconstruction accuracy in presence of affine motion artifacts of approximately
30% compared to conventional SVR in synthetic experiments. Furthermore, we have
evaluated our method qualitatively and quantitatively on real fetal MRI data
subject to maternal breathing and sudden fetal movements. We evaluate
peak-signal-to-noise ratio (PSNR), structural similarity index (SSIM), and
cross correlation (CC) with respect to the originally acquired data and provide
a method for visual inspection of reconstruction uncertainty. With these
experiments we demonstrate successful application of PVR motion compensation to
the whole uterus, the human fetus, and the human placenta.Comment: 10 pages, 13 figures, submitted to IEEE Transactions on Medical
Imaging. v2: wadded funders acknowledgements to preprin
Technology And Teaching Screencast Tutorials Enhance Student Learning of Statistics
Abstract Although the use of computer-assisted instruction has rapidly increased, there is little empirical research evaluating these technologies, specifically within the context of teaching statistics. The authors assessed the effect of screencast tutorials on learning outcomes, including statistical knowledge, application, and interpretation. Students from four sections of a psychology course in statistics were randomly assigned to a control text tutorial or an experimental video tutorial group and were tasked with completing a novel statistics problem. Previous math experience, math and computer anxiety, and course grades were also controlled. The results demonstrate that screencast tutorials are an effective and efficient tool for enhancing student learning, especially for higher order conceptual statistical knowledge compared to traditional instructional techniques
Masses of Astrometrically-Discovered and Imaged Binaries: G 78-28AB and GJ 231.1BC
The Stellar Planet Survey (STEPS) is an ongoing astrometric search for giant
planets and brown dwarfs around a sample of ~30 M-dwarfs. We have discovered
several low-mass companions by measuring the motion of our target stars
relative to their reference frames. The highest mass discovery thus far is G
78-28B, a companion to the M-dwarf G 78-28A. The orbital period is 4.18 +/-
0.03 y, the system mass is 0.565 +/- 0.055 Msolar, and the semi-major axis is
2.19 +/- 0.10 AU. Imaging observations with the Keck laser guide star adaptive
optics (LGSAO) and the Palomar AO instruments resolved the system and also
yielded JHK-band delta magnitudes. We use the orbital solution, light ratios,
and mass-luminosity relationships to derive component masses of MA = 0.370 +/-
0.034 Msolar and MB = 0.195 +/- 0.021 Msolar. G 78-28B is of type M4 V based
upon its colors and mass. We also discovered GJ 231.1C, a companion to GJ
231.1B, with STEPS and imaged the companion with LGSAO and Palomar AO, but the
orbital period is longer than our observing baseline; thus the system
parameters are less constrained. In GJ 231.1BC the masses are MB = 0.25 +/-
0.06 Msolar and MC =0.12 +/- 0.02 Msolar. The inferred spectral type of GJ
231.1C is M5 V. We demonstrate the results of the current state of mass
estimation techniques with our data.Comment: 25 pages, 8 figures, accepted for Ap
An Automated Method for the Detection and Extraction of HI Self-Absorption in High-Resolution 21cm Line Surveys
We describe algorithms that detect 21cm line HI self-absorption (HISA) in
large data sets and extract it for analysis. Our search method identifies HISA
as spatially and spectrally confined dark HI features that appear as negative
residuals after removing larger-scale emission components with a modified CLEAN
algorithm. Adjacent HISA volume-pixels (voxels) are grouped into features in
(l,b,v) space, and the HI brightness of voxels outside the 3-D feature
boundaries is smoothly interpolated to estimate the absorption amplitude and
the unabsorbed HI emission brightness. The reliability and completeness of our
HISA detection scheme have been tested extensively with model data. We detect
most features over a wide range of sizes, linewidths, amplitudes, and
background levels, with poor detection only where the absorption brightness
temperature amplitude is weak, the absorption scale approaches that of the
correlated noise, or the background level is too faint for HISA to be
distinguished reliably from emission gaps. False detection rates are very low
in all parts of the parameter space except at sizes and amplitudes approaching
those of noise fluctuations. Absorption measurement biases introduced by the
method are generally small and appear to arise from cases of incomplete HISA
detection. This paper is the third in a series examining HISA at high angular
resolution. A companion paper (Paper II) uses our HISA search and extraction
method to investigate the cold atomic gas distribution in the Canadian Galactic
Plane Survey.Comment: 39 pages, including 14 figure pages; to appear in June 10 ApJ, volume
626; figure quality significantly reduced for astro-ph; for full resolution,
please see http://www.ras.ucalgary.ca/~gibson/hisa/cgps1_survey
Trends and Issues with the English Assessment and Class Placement of First Year Students at Kyoei University : Department of International Business Management
本論文は、2009 ~ 2011 年に共栄大学国際経営学部(IBMD) に入学した学生の英語の能力の低下について述べたものである。本論は、クラス分けテストの得点と毎年の傾向を議論した上で、英語のカリキュラムが大きく変わっ現在でも、これ迄同様のクラス分けテストの存在意義、必要性について述べている。又、クラス分けの不適合は、学生の、(授業が簡単すぎたり難しすぎたりしての)退屈な授業の受講、学習意欲の消失、幻滅、無断欠席、と一連の流れに陥り最終的に退学という最悪の結果にもなりかねない事も書き加えている。This paper discusses the decline in the English ability of students entering the InternationalBusiness Management Department (IBMD) of Kyoei University between 2009 and 2011, and discussesthe placement test scores and yearly trends. It also questions the administration\u27s rationalefor administering the current test in the light of recent English curriculum changes, and the pre-assigningof students to English classes according to demands completely unrelated to their Englishlanguage educational needs. In addition, the paper discusses the de-motivation, boredom and disillusionmentthat may occur due to class miss-assignment, and its possible links to truancy and dropout rates
キョウエイ ダイガク プレースメント テスト ニタイスル ヒョウカ
この論文は、初めての試みである2010 年共栄大学プレースメント・テストにおける分析を主旨とする。このテストは、依然として多くの微調整や課題を要するものの、その統計的な分析の結果、その実践における確固たる有効性を証明することができた。このテストは、プレースメント・テストとしては、その信頼性においてもその目的を果たすものして適切なものであるということがこの論文における統計分析でよって証明ができたと言える。さらにこのテストをモデルとして、今後のプレースメント・テストにおける将来的な展望が大いに開けたと言えよう。This paper discusses the development, and analysis of the newly developed placement test forthe 2010 International Business Management Department (IBMD) first year intake. It acknowledgesthat while a small number of items may need further examination or improvement, the statisticalanalysis provides solid empirical evidence about the performance of the test. It is clear that the testis suitable for the purpose for which it was designed and that the satisfactory reliability and validityevidence gathered proves that it is a dependable test. Moreover it demonstrates that this test can beused with confidence now, and as a model on which to build future versions
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