10,416 research outputs found
Wide-angle flat field telescope
Described is an unobscured three mirror wide angle telescopic imaging system comprised of an input baffle which provides a 20 deg (Y axis) x 30 deg (X axis) field of view, a primary mirror having a convex spherical surface, a secondary mirror having a concave ellipsoidal reflecting surface, a tertiary mirror having a concave spherical reflecting surface. The mirrors comprise mirror elements which are offset segments of parent mirrors whose axes and vertices commonly lie on the system's optical axis. An iris diaphragm forming an aperture stop is located between the secondary and tertiary mirror with its center also being coincident with the optical axis and being further located at the beam waist of input light beams reflected from the primary and secondary mirror surfaces. At the system focus following the tertiary mirror is located a flat detector which may be, for example, a TV imaging tube or a photographic film. When desirable, a spectral transmission filter is placed in front of the detector in close proximity thereto
Coldâwater coral assemblages on vertical walls from the Northeast Atlantic
Aim
In this study, we assess patterns of coldâwater coral assemblages observed on deepâsea vertical walls. Similar to their shallowâwater counterparts, vertical and overhanging walls in the deep sea can host highly diverse communities, but because of their geometry, these habitats are generally overlooked and remain poorly known. These vertical habitats are however of particular interest, because they can protect vulnerable coral ecosystems from trawling activities. As such, it is important to understand their ecology and assess their global importance.
Location
Vertical walls on complex geomorphic features, in particular walls of the Rockall Bank Slope Failure Escarpment, Whittard and Explorer Canyons, Northeast Atlantic.
Methods
Video analysis of remotely operated vehicle transects carried out at five sites is used to investigate differences in species composition and diversity across walls and to compare those to nearby coldâwater coral sites on flat terrain. A highâresolution photogrammetric reconstruction is further employed to examine whether wall complexity plays a role in promoting niche differentiation at very fine spatial scales.
Results
The investigated walls showed differences in species assemblage both across walls and in comparison to flat sites, with the fineâscale heterogeneity engendered by walls allowing niche differentiation between closely related taxa.
Main Conclusions
Vertical walls represent an important coldâwater coral habitat with differences in species composition across walls within a region, illustrating their role in driving diversity patterns. Based on publicly available bathymetric datasets and a catalogue of broadâscale terrain features, globally over 8,000 features are likely to have vertical walls and coldâwater corals, which highlight the need to consider deepâsea vertical habitats in current conservation efforts
Circuit of Culture: A Critical Look at Dilbert and Workplace Learning
As a cultural artifact, the Dilbert comic strip has generated both amusement and consternation, particularly for corporate trainers. This paper summarizes a year of research on Dilbert and its surrounding discourse in order to extend the critique of corporate education and Human Resource Development (HRD) into the cultural realm
Catching VY Sculptoris in a low state
Context. In the context of a large campaign to determine the system
parameters of high mass transfer cataclysmic variables, we found VY Scl in a
low state in 2008. Aims. Making use of this low state, we study the stellar
components of the binary with little influence of the normally dominating
accretion disc. Methods. Time-resolved spectroscopy and photometry of VY Scl
taken during the low state are presented. We analysed the light-curve and
radial velocity curve and use time-resolved spectroscopy to calculate Doppler
maps of the dominant emission lines. Results. The spectra show narrow emission
lines of Halpha, Hbeta, HeI, NaID, and FeII, as well as faint TiO absorption
bands that trace the motion of the irradiated secondary star, and Halpha and
HeI emission line wings that trace the motion of the white dwarf. From these
radial velocities, we find an orbital period of 3.84 h, and put constraints on
binary parameters such as the mass ratio M2/M1 of 0.43 and the inclination of
15 deg. With a secondary's mass between 0.3 and 0.35 Msol, we derive the mass
for the white dwarf as M1 = 0.6-0.1 Msol.Comment: 8 pages, 9 figures, accepted for publication in A&
Laserwire at the Accelerator Test Facility 2 with Sub-Micrometre Resolution
A laserwire transverse electron beam size measurement system has been
developed and operated at the Accelerator Test Facility 2 (ATF2) at KEK.
Special electron beam optics were developed to create an approximately 1 x 100
{\mu}m (vertical x horizontal) electron beam at the laserwire location, which
was profiled using a 150 mJ, 71 ps laser pulse with a wavelength of 532 nm. The
precise characterisation of the laser propagation allows the non-Gaussian
transverse profiles of the electron beam caused by the laser divergence to be
deconvolved. A minimum vertical electron beam size of 1.07 0.06 (stat.)
0.05 (sys.) {\mu}m was measured. A vertically focussing quadrupole just
before the laserwire was varied whilst making laserwire measurements and the
projected vertical emittance was measured to be 82.56 3.04 pm rad.Comment: 17 pages, 26 figures, submitted to Phys. Rev. ST Accel. Beam
Shaping Self-Disciplined Workers: A Study of Silent Power in HRD
The intent of this case study was to examine power theories in a singular HRD context in such a way that problematizes the consequences of power
Education as Function of Productivity: An Hermeneutic Study of Standards on Ethics and Integrity in Human Resource Development Texts
This critical hermeneutic analysis of the AHRD Standards on Ethics and Integrity and six HRD textbooks identifies unexamined assumptions and silences related to the practice of HRD
Irreconcilable Differences: Critical Feminism, Learning at Work, and HRD
This study explored the contradictions among critical feminist theory, Human Resource Development, and the reality of women\u27s experiences. Missing from the HRD literature, with its managerial focus, is the centrality of workers\u27, particularly women\u27s experiences of HRD and the gendered nature of work itself
Correction: The Complete Sequence of the Acacia ligulata Chloroplast Genome Reveals a Highly Divergent clpP1 Gene
The authors would like to amend this article based on the discovery that the originally published Acacia ligulata sequence contains assembly errors, which came to light after the publication of the article
Radiation-Hydrodynamic Simulations of Collapse and Fragmentation in Massive Protostellar Cores
We simulate the early stages of the evolution of turbulent, virialized,
high-mass protostellar cores, with primary attention to how cores fragment, and
whether they form a small or large number of protostars. Our simulations use
the Orion adaptive mesh refinement code to follow the collapse from ~0.1 pc
scales to ~10 AU scales, for durations that cover the main fragmentation phase,
using three-dimensional gravito-radiation hydrodynamics. We find that for a
wide range of initial conditions radiation feedback from accreting protostars
inhibits the formation of fragments, so that the vast majority of the collapsed
mass accretes onto one or a few objects. Most of the fragmentation that does
occur takes place in massive, self-shielding disks. These are driven to
gravitational instability by rapid accretion, producing rapid mass and angular
momentum transport that allows most of the gas to accrete onto the central star
rather than forming fragments. In contrast, a control run using the same
initial conditions but an isothermal equation of state produces much more
fragmentation, both in and out of the disk. We conclude that massive cores with
observed properties are not likely to fragment into many stars, so that, at
least at high masses, the core mass function probably determines the stellar
initial mass function. Our results also demonstrate that simulations of massive
star forming regions that do not include radiative transfer, and instead rely
on a barotropic equation of state or optically thin heating and cooling curves,
are likely to produce misleading results.Comment: 23 pages, 18 figures, emulateapj format. Accepted to ApJ. This
version has minor typo fixes and small additions, no significant changes.
Resolution of images severely degraded to fit within size limit. Download the
full paper from http://www.astro.princeton.edu/~krumholz/recent.htm
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