530 research outputs found
The Forester Takes Up His Camera
There is no excuse for making poor photographic exposures in the woods, if a few simple tips are kept in mind. The forester is often anxious to get pictures of objects in the woods which ordinary cameras cannot take by snapshot methods
An Intersubjective Analysis of Engineering Leadership Across Organizational Locations: Implications for Higher Education
Engineering leadership education has become increasingly popular over the past decade in response to national calls for educational change. Despite the growing popularity of the movement, however, reform efforts continue to be piecemeal in their delivery, driven largely by the priorities of program leaders who established them (Graham, 2012). If we as engineering educators wish to more systematically develop leadership skills in our students, we should begin by empirically examining and defining our phenomenon of interest: engineering leadership. Our article takes up this challenge by investigating how 82 engineers in five organizationally distinct roles define leadership and how their respective insights are shaped by their diverse organizational locations. After weaving together the perspectives of engineers in industry, human resource professionals, entrepreneurs, politicians and interns, we propose a poly-vocal definition of engineering leadership and identify practical implications for engineering leadership educators.
En rĂ©ponse aux appels Ă rĂ©former le systĂšme de lâĂ©ducation, la formation de leaders en gĂ©nie a gagnĂ© en popularitĂ© au cours des dix derniĂšres annĂ©es. MalgrĂ© la popularitĂ© croissante de ce mouvement, les rĂ©formes demeurent partiales et suivent largement les prioritĂ©s des directeurs de programmes qui les mettent en place (Graham, 2012). Si, en tant que formateurs dâingĂ©nieurs, nous souhaitons perfectionner systĂ©matiquement les compĂ©tences en leadership de nos Ă©tudiants, il nous faut commencer par une analyse empirique qui permette de dĂ©finir prĂ©cisĂ©ment notre objet, soit le leadership en gĂ©nie. Notre article relĂšve le dĂ©fi en analysant les façons dont 82 ingĂ©nieurs occupant cinq rĂŽles distincts dans une organisation dĂ©finissent le leadership, et les façons dont leurs positions institutionnelles Ă©tablissent leurs perspectives. En tenant compte des perspectives dâingĂ©nieurs de lâindustrie, de professionnels des ressources humaines, dâentrepreneurs, de politiciens et de stagiaires, nous proposons une dĂ©finition plurivoque du leadership en gĂ©nie, et nous en identifions les implications pratiques pour les Ă©ducateurs du domaine
DiFX2: A more flexible, efficient, robust and powerful software correlator
Software correlation, where a correlation algorithm written in a high-level
language such as C++ is run on commodity computer hardware, has become
increasingly attractive for small to medium sized and/or bandwidth constrained
radio interferometers. In particular, many long baseline arrays (which
typically have fewer than 20 elements and are restricted in observing bandwidth
by costly recording hardware and media) have utilized software correlators for
rapid, cost-effective correlator upgrades to allow compatibility with new,
wider bandwidth recording systems and improve correlator flexibility. The DiFX
correlator, made publicly available in 2007, has been a popular choice in such
upgrades and is now used for production correlation by a number of
observatories and research groups worldwide. Here we describe the evolution in
the capabilities of the DiFX correlator over the past three years, including a
number of new capabilities, substantial performance improvements, and a large
amount of supporting infrastructure to ease use of the code. New capabilities
include the ability to correlate a large number of phase centers in a single
correlation pass, the extraction of phase calibration tones, correlation of
disparate but overlapping sub-bands, the production of rapidly sampled
filterbank and kurtosis data at minimal cost, and many more. The latest version
of the code is at least 15% faster than the original, and in certain situations
many times this value. Finally, we also present detailed test results
validating the correctness of the new code.Comment: 28 pages, 9 figures, accepted for publication in PAS
Precision astrometry of pulsars and other compact radio sources in the globular cluster M15
The globular cluster (GC) M15 (NGC 7078) is host to at least eight pulsars and two low mass X-ray binaries (LMXBs), one of which is also visible in the radio regime. Here we present the results of a multi-epoch global very long baseline interferometry (VLBI) campaign aiming at i) measuring the proper motion of the known compact radio sources; ii) finding and classifying thus far undetected compact radio sources in the GC; and iii) detecting a signature of the putative intermediate mass black hole (IMBH) proposed to reside at the core of M15. We measure the sky motion in right ascension (”a) and declination (”d) of the pulsars M15A and M15C and of the LMXB AC211 to be (”a,”d)M15A = (-0.54 ± 0.14,-4.33 ± 0.25) mas yr-1, (”a,”d)M15C = (-0.75 ± 0.09,-3.52 ± 0.13) mas yr-1, and (”a, ”d)AC211 = (-0.46 ± 0.08,-4.31 ± 0.20) mas yr-1, respectively. Based on these measurements we estimate the global proper motion of M15 to be (”a, ”d) = (-0.58 ± 0.18,-4.05 ± 0.34) mas yr -1. We detect two previously known but unclassified compact sources within our field of view. Our observations indicate that one them is of extragalactic origin while the other one is a foreground source, quite likely an LMXB. The double neutron star system M15C became fainter during the observations, disappeared for one year and is now observable again-an effect possibly caused by geodetic precession. The LMXB AC211 shows a double lobed structure in one of the observations indicative of an outburst during this campaign. With the inclusion of the last two of a total of seven observations we confirm the upper mass limit for a putative IMBH to be Mâą< 500 M·. © 2014 ESO
Single-particle-sensitive imaging of freely propagating ultracold atoms
We present a novel imaging system for ultracold quantum gases in expansion.
After release from a confining potential, atoms fall through a sheet of
resonant excitation laser light and the emitted fluorescence photons are imaged
onto an amplified CCD camera using a high numerical aperture optical system.
The imaging system reaches an extraordinary dynamic range, not attainable with
conventional absorption imaging. We demonstrate single-atom detection for
dilute atomic clouds with high efficiency where at the same time dense
Bose-Einstein condensates can be imaged without saturation or distortion. The
spatial resolution can reach the sampling limit as given by the 8 \mu m pixel
size in object space. Pulsed operation of the detector allows for slice images,
a first step toward a 3D tomography of the measured object. The scheme can
easily be implemented for any atomic species and all optical components are
situated outside the vacuum system. As a first application we perform
thermometry on rubidium Bose-Einstein condensates created on an atom chip.Comment: 24 pages, 10 figures. v2: as publishe
On the Calibration of Full-polarization 86GHz Global VLBI Observations
We report the development of a semi-automatic pipeline for the calibration of
86 GHz full-polarization observations performed with the Global Millimeter-VLBI
array (GMVA) and describe the calibration strategy followed in the data
reduction. Our calibration pipeline involves non-standard procedures, since
VLBI polarimetry at frequencies above 43 GHz is not yet well established. We
also present, for the first time, a full-polarization global-VLBI image at 86
GHz (source 3C 345), as an example of the final product of our calibration
pipeline, and discuss the effect of instrumental limitations on the fidelity of
the polarization images. Our calibration strategy is not exclusive for the
GMVA, and could be applied on other VLBI arrays at millimeter wavelengths. The
use of this pipeline will allow GMVA observers to get fully-calibrated datasets
shortly after the data correlation.Comment: 10 pages, 10 figures. Accepted for publication in A&
Zooming towards the Event Horizon - mm-VLBI today and tomorrow
Global VLBI imaging at millimeter and sub-millimeter wavelength overcomes the
opacity barrier of synchrotron self-absorption in AGN and opens the direct view
into sub-pc scale regions not accessible before. Since AGN variability is more
pronounced at short millimeter wavelength, mm-VLBI can reveal structural
changes in very early stages after outbursts. When combined with observations
at longer wavelength, global 3mm and 1mm VLBI adds very detailed information.
This helps to determine fundamental physical properties at the jet base, and in
the vicinity of super-massive black holes at the center of AGN. Here we present
new results from multi-frequency mm-VLBI imaging of OJ287 during a major
outburst. We also report on a successful 1.3mm VLBI experiment with the APEX
telescope in Chile. This observation sets a new record in angular resolution.
It also opens the path towards future mm-VLBI with ALMA, which aims at the
mapping of the black hole event horizon in nearby galaxies, and the study of
the roots of jets in AGN.Comment: 6 pages, to appear in 11th European VLBI Network Symposium, ed. P.
Charlot et al., Bordeaux (France), October 9-12, 201
Biotech Eucalyptus can sustainably address societyâs need for wood: the example of freeze tolerant Eucalyptus in the southeastern U.S
Key Contributions by the Swiss Tropical and Public Health Institute Towards New and Better Drugs for Tropical Diseases
Thanks to its expertise in clinical research, epidemiology, infectious diseases, microbiology, parasitology, public health, translational research and tropical medicine, coupled with deeply rooted partnerships with institutions in low- and middle-income countries (LMICs), the Swiss Tropical and Public Health Institute (Swiss TPH) has been a key contributor in many drug research and development consortia involving academia, pharma and product development partnerships. Our know-how of the maintenance of parasites and their life-cycles in the laboratory, plus our strong ties to research centres and disease control programme managers in LMICs with access to field sites and laboratories, have enabled systems for drug efficacy testing in vitro and in vivo, clinical research, and modelling to support the experimental approaches. Thus, Swiss TPH has made fundamental contributions towards the development of new drugs â and the better use of old drugs â for neglected tropical diseases and infectious diseases of poverty, such as Buruli ulcer, Chagas disease, food-borne trematodiasis (e.g. clonorchiasis, fascioliasis and opisthorchiasis), human African trypanosomiasis, leishmaniasis, malaria, schistosomiasis, soil-transmitted helminthiasis and tuberculosis. In this article, we show case the success stories of molecules to which Swiss TPH has made a substantial contribution regarding their use as anti-infective compounds with the ultimate aim to improve peopleâs health and well-being
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