3,535 research outputs found
How the Sando Search Tool Recommends Queries
Developers spend a significant amount of time searching their local codebase.
To help them search efficiently, researchers have proposed novel tools that
apply state-of-the-art information retrieval algorithms to retrieve relevant
code snippets from the local codebase. However, these tools still rely on the
developer to craft an effective query, which requires that the developer is
familiar with the terms contained in the related code snippets. Our empirical
data from a state-of-the-art local code search tool, called Sando, suggests
that developers are sometimes unacquainted with their local codebase. In order
to bridge the gap between developers and their ever-increasing local codebase,
in this paper we demonstrate the recommendation techniques integrated in Sando
High-Fidelity Spectroscopy at the Highest Resolutions
High-fidelity spectroscopy presents challenges for both observations and in
designing instruments. High-resolution and high-accuracy spectra are required
for verifying hydrodynamic stellar atmospheres and for resolving intergalactic
absorption-line structures in quasars. Even with great photon fluxes from large
telescopes with matching spectrometers, precise measurements of line profiles
and wavelength positions encounter various physical, observational, and
instrumental limits. The analysis may be limited by astrophysical and telluric
blends, lack of suitable lines, imprecise laboratory wavelengths, or
instrumental imperfections. To some extent, such limits can be pushed by
forming averages over many similar spectral lines, thus averaging away small
random blends and wavelength errors. In situations where theoretical
predictions of lineshapes and shifts can be accurately made (e.g., hydrodynamic
models of solar-type stars), the consistency between noisy observations and
theoretical predictions may be verified; however this is not feasible for,
e.g., the complex of intergalactic metal lines in spectra of distant quasars,
where the primary data must come from observations. To more fully resolve
lineshapes and interpret wavelength shifts in stars and quasars alike, spectral
resolutions on order R=300,000 or more are required; a level that is becoming
(but is not yet) available. A grand challenge remains to design efficient
spectrometers with resolutions approaching R=1,000,000 for the forthcoming
generation of extremely large telescopes.Comment: 6 pages, 4 figures, to appear in Reviews in Modern Astronomy vol. 22
(2010
A uranium-series date from Wall End Cave, Silverdale, northwest England: its palaeoclimatic and archaeological significance
Uranium-series dating of a stalagmite floor from a relict cave in the Morecambe Bay karst indicates speleothem deposition occurred between 13,567 to 8539 years BP. Comparison with other cave archaeological sites where a stalagmite floor occurs in a similar stratigraphical position suggests the first human occupation of the region following the Last Glacial Maximum may have occurred in the early part of the Windermere/Late Glacial Interstadial
A search for molecules in damped Lyman-alpha absorbers occulting millimetre-loud quasars
We have used the SEST 15-metre and Onsala 20-metre telescopes to perform deep
(r.m.s. >~ 30 mJy) integrations of various molecular rotational transitions
towards damped Lyman-alpha absorption systems (DLAs) known to occult
millimetre-loud quasars. We have observed 6 new systems and improved the
existing limits for 11 transitions. These limits may be approaching the
sensitivities required to detect new systems and we present a small number of
candidate systems which we believe warrant further observation.Comment: 7 pages, 1 PS figure, 4 tables. Accepted by A&
Discovery of a Perseus-like cloud in the early Universe: HI-to-H2 transition, carbon monoxide and small dust grains at zabs=2.53 towards the quasar J0000+0048
We present the discovery of a molecular cloud at zabs=2.5255 along the line
of sight to the quasar J0000+0048. We perform a detailed analysis of the
absorption lines from ionic, neutral atomic and molecular species in different
excitation levels, as well as the broad-band dust extinction. We find that the
absorber classifies as a Damped Lyman-alpha system (DLA) with
logN(HI)(cm^-2)=20.8+/-0.1. The DLA has super-Solar metallicity with a
depletion pattern typical of cold gas and an overall molecular fraction ~50%.
This is the highest f-value observed to date in a high-z intervening system.
Most of the molecular hydrogen arises from a clearly identified narrow (b~0.7
km/s), cold component in which CO molecules are also found, with logN(CO)~15.
We study the chemical and physical conditions in the cold gas. We find that the
line of sight probes the gas deep after the HI-to-H2 transition in a ~4-5
pc-size cloud with volumic density nH~80 cm^-3 and temperature of only 50 K.
Our model suggests that the presence of small dust grains (down to about 0.001
{\mu}m) and high cosmic ray ionisation rate (zeta_H a few times 10^-15 s^-1)
are needed to explain the observed atomic and molecular abundances. The
presence of small grains is also in agreement with the observed steep
extinction curve that also features a 2175 A bump. The properties of this cloud
are very similar to what is seen in diffuse molecular regions of the nearby
Perseus complex. The high excitation temperature of CO rotational levels
towards J0000+0048 betrays however the higher temperature of the cosmic
microwave background. Using the derived physical conditions, we correct for a
small contribution (0.3 K) of collisional excitation and obtain TCMB(z =
2.53)~9.6 K, in perfect agreement with the predicted adiabatic cooling of the
Universe. [abridged]Comment: 24 pages, 24 figures, accepted for publication in A&
Role of substrate supply on microbial carbon use efficiency and its role in interpreting soil microbial community-level physiological profiles (CLPP)
An Instrumented Glove to Assess Manual Dexterity in Simulation-Based Neurosurgical Education
ABSTRACT: The traditional neurosurgical apprenticeship scheme includes the assessment of trainee’s
manual skills carried out by experienced surgeons. However, the introduction of surgical simulation
technology presents a new paradigm where residents can refine surgical techniques on a simulator
before putting them into practice in real patients. Unfortunately, in this new scheme, an experienced
surgeon will not always be available to evaluate trainee’s performance. For this reason, it is necessary
to develop automatic mechanisms to estimate metrics for assessing manual dexterity in a quantitative
way. Authors have proposed some hardware-software approaches to evaluate manual dexterity
on surgical simulators. This paper presents IGlove, a wearable device that uses inertial sensors
embedded on an elastic glove to capture hand movements. Metrics to assess manual dexterity are
estimated from sensors signals using data processing and information analysis algorithms. It has
been designed to be used with a neurosurgical simulator called Daubara NS Trainer, but can be
easily adapted to another benchtop- and manikin-based medical simulators. The system was tested
with a sample of 14 volunteers who performed a test that was designed to simultaneously evaluate
their fine motor skills and the IGlove’s functionalities. Metrics obtained by each of the participants
are presented as results in this work; it is also shown how these metrics are used to automatically
evaluate the level of manual dexterity of each volunteer
Molecular hydrogen in high-redshift Damped Lyman-alpha systems: The VLT/UVES database
We present the current status of ongoing searches for molecular hydrogen in
high-redshift (1.8 < zabs <= 4.2) Damped Lyman-alpha systems (DLAs)
capitalising on observations performed with the ESO Very Large Telescope (VLT)
Ultraviolet and Visual Echelle Spectrograph (UVES). We identify 77 DLAs/strong
sub-DLAs, with log N(HI) >= 20 and z_abs > 1.8, which have data that include
redshifted H2 Lyman and/or Werner-band absorption lines. This sample of HI, H2
and metal line measurements, performed in an homogeneous manner, is more than
twice as large as our previous sample (Ledoux et al. 2003) and considers every
system in which searches for H2 could be completed so far, including all
non-detections. H2 is detected in thirteen of the systems with molecular
fractions of values between f=5x10^-7 and f=0.1, where f=2N(H2)/(2N(H2)+N(HI)).
Upper limits are measured for the remaining 64 systems with detection limits of
typically log N(H2)=14.3, corresponding to log f<-5. We find that about 35% of
the DLAs with metallicities relative to solar [X/H]>=-1.3 (i.e., 1/20th solar),
with X = Zn, S or Si, have molecular fractions log f>-4.5, while H2 is detected
-- regardless of the molecular fraction -- in 50% of them. In contrast, only
about 4% of the [X/H]-4.5. We show that the presence of
H2 does not strongly depend on the total neutral hydrogen column density,
although the probability of finding log f>-4.5 is higher for log N(HI)>=20.8
than below this limit (19% and 7% respectively). The overall H2 detection rate
in log N(HI)>=20 DLAs is found to be about 16% (10% considering only log f>-4.5
detections) after correction for a slight bias towards large N(HI). [truncated]Comment: 11 pages, 1 table, 10 figures. Accepted for publication in A&
Cellular structure of -Brauer algebras
In this paper we consider the -Brauer algebra over a commutative
noetherian domain. We first construct a new basis for -Brauer algebras, and
we then prove that it is a cell basis, and thus these algebras are cellular in
the sense of Graham and Lehrer. In particular, they are shown to be an iterated
inflation of Hecke algebras of type Moreover, when is a field of
arbitrary characteristic, we determine for which parameters the -Brauer
algebras are quasi-heredity. So the general theory of cellular algebras and
quasi-hereditary algebras applies to -Brauer algebras. As a consequence, we
can determine all irreducible representations of -Brauer algebras by linear
algebra methods
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