5,054 research outputs found
Reproductive morphology of three species of deep-water precious corals from the Hawaiian Archipelago : Gerardia Sp., Corallium secundum, and Corallium lauuense
Author Posting. © University of Miami - Rosenstiel School of Marine and Atmospheric Science, 2007. This article is posted here by permission of University of Miami - Rosenstiel School of Marine and Atmospheric Science for personal use, not for redistribution. The definitive version was published in Bulletin of Marine Science 81 (2007): 533-542.Three species of deep-sea corals were collected from several locations in the Hawaiian Archipelago. These species have been called "precious corals" because of their extensive use in the jewelry industry. Two octocorals Corallium lauuense Bayer, 1956 (red coral) and Corallium secundum Dana, 1846 (pink coral), and a zoanthid, Gerardia sp. (gold coral) collected between August and November in 1998-2004, were all histologically analysed for reproductive tissues. All three species of precious corals appear to be gonochoric (both males and females of all species being identified—though with C. lauuense more reproductive polyps are needed to conclusively confirm this), with the two species of Corallium having reproductive material contained within siphonozooids rather than the main polyp (autozoid). Maximum oocyte sizes were: Gerardia sp. ∼300 μm, C. secundum ∼600 μm, and C. lauuense ∼660 μm. All three species are hypothesized to have spawned during the collection season. Gerardia was observed spawning during collection, and histological sections of the two Corallium species show areas where gametes appear to be missing. Gerardia sp. has a single cohort of gametes developing, which may suggest seasonal reproduction, and the two Corallium species show multiple sizes present in single individuals, suggesting a periodic or quasi-continuous reproductive periodicity.This project was supported by ship time grants from the Hawaii Undersea Research Laboratory
and Hawaii SeaGrant as well as National Oceanic and Atmospheric Administration’s
Office of Ocean Exploration Award No. NA03OAR4600108. A.R.B. received support from an
EPA STAR graduate research fellowship and a Woods Hole Oceanographic Institution postdoctoral
scholarship
Performance of AAOmega: the AAT multi-purpose fibre-fed spectrograph
AAOmega is the new spectrograph for the 2dF fibre-positioning system on the
Anglo-Australian Telescope. It is a bench-mounted, double-beamed design, using
volume phase holographic (VPH) gratings and articulating cameras. It is fed by
392 fibres from either of the two 2dF field plates, or by the 512 fibre SPIRAL
integral field unit (IFU) at Cassegrain focus. Wavelength coverage is 370 to
950nm and spectral resolution 1,000-8,000 in multi-Object mode, or 1,500-10,000
in IFU mode. Multi-object mode was commissioned in January 2006 and the IFU
system will be commissioned in June 2006.
The spectrograph is located off the telescope in a thermally isolated room
and the 2dF fibres have been replaced by new 38m broadband fibres. Despite the
increased fibre length, we have achieved a large increase in throughput by use
of VPH gratings, more efficient coatings and new detectors - amounting to a
factor of at least 2 in the red. The number of spectral resolution elements and
the maximum resolution are both more than doubled, and the stability is an
order of magnitude better.
The spectrograph comprises: an f/3.15 Schmidt collimator, incorporating a
dichroic beam-splitter; interchangeable VPH gratings; and articulating red and
blue f/1.3 Schmidt cameras. Pupil size is 190mm, determined by the competing
demands of cost, obstruction losses, and maximum resolution. A full suite of
VPH gratings has been provided to cover resolutions 1,000 to 7,500, and up to
10,000 at particular wavelengths.Comment: 13 pages, 4 figures; presented at SPIE, Astronomical Telescopes and
Instrumentation, 24 - 31 May 2006, Orlando, Florida US
PinR mediates the generation of reversible population diversity in Streptococcus zooepidemicus
Opportunistic pathogens must adapt to and survive in a wide range of complex ecosystems. Streptococcus zooepidemicus is an opportunistic pathogen of horses and many other animals, including humans. The assembly of different surface architecture phenotypes from one genotype is likely to be crucial to the successful exploitation of such an opportunistic lifestyle. Construction of a series of mutants revealed that a serine recombinase, PinR, inverts 114 bp of the promoter of SZO_08560, which is bordered by GTAGACTTTA and TAAAGTCTAC inverted repeats. Inversion acts as a switch, controlling the transcription of this sortase-processed protein, which may enhance the attachment of S. zooepidemicus to equine trachea. The genome of a recently sequenced strain of S. zooepidemicus, 2329 (Sz2329), was found to contain a disruptive internal inversion of 7 kb of the FimIV pilus locus, which is bordered by TAGAAA and TTTCTA inverted repeats. This strain lacks pinR and this inversion may have become irreversible following the loss of this recombinase. Active inversion of FimIV was detected in three strains of S. zooepidemicus, 1770 (Sz1770), B260863 (SzB260863) and H050840501 (SzH050840501), all of which encoded pinR. A deletion mutant of Sz1770 that lacked pinR was no longer capable of inverting its internal region of FimIV. The data highlight redundancy in the PinR sequence recognition motif around a short TAGA consensus and suggest that PinR can reversibly influence the wider surface architecture of S. zooepidemicus, providing this organism with a bet-hedging solution to survival in fluctuating environments
Precise multimodal optical control of neural ensemble activity.
Understanding brain function requires technologies that can control the activity of large populations of neurons with high fidelity in space and time. We developed a multiphoton holographic approach to activate or suppress the activity of ensembles of cortical neurons with cellular resolution and sub-millisecond precision. Since existing opsins were inadequate, we engineered new soma-targeted (ST) optogenetic tools, ST-ChroME and IRES-ST-eGtACR1, optimized for multiphoton activation and suppression. Employing a three-dimensional all-optical read-write interface, we demonstrate the ability to simultaneously photostimulate up to 50 neurons distributed in three dimensions in a 550 × 550 × 100-µm3 volume of brain tissue. This approach allows the synthesis and editing of complex neural activity patterns needed to gain insight into the principles of neural codes
EquiFACS: the Equine Facial Action Coding System
Although previous studies of horses have investigated their facial expressions in specific contexts, e.g. pain, until now there has been no methodology available that documents all the possible facial movements of the horse and provides a way to record all potential facial configurations. This is essential for an objective description of horse facial expressions across a range of contexts that reflect different emotional states. Facial Action Coding Systems (FACS) provide a systematic methodology of identifying and coding facial expressions on the basis of underlying facial musculature and muscle movement. FACS are anatomically based and document all possible facial movements rather than a configuration of movements associated with a particular situation. Consequently, FACS can be applied as a tool for a wide range of research questions. We developed FACS for the domestic horse (Equus caballus) through anatomical investigation of the underlying musculature and subsequent analysis of naturally occurring behaviour captured on high quality video. Discrete facial movements were identified and described in terms of the underlying muscle contractions, in correspondence with previous FACS systems. The reliability of others to be able to learn this system (EquiFACS) and consistently code behavioural sequences was high—and this included people with no previous experience of horses. A wide range of facial movements were identified, including many that are also seen in primates and other domestic animals (dogs and cats). EquiFACS provides a method that can now be used to document the facial movements associated with different social contexts and thus to address questions relevant to understanding social cognition and comparative psychology, as well as informing current veterinary and animal welfare practices
Extending and validating a human papillomavirus (HPV) knowledge measure in a national sample of Canadian parents of boys
As the human papillomavirus (HPV) vaccine is now recommended for males, a reliable, comprehensive HPV knowledge measurement tool which addresses issues relevant to males is needed. We aimed to replicate, validate and test the comprehensiveness of an existing general HPV and an HPV vaccination knowledge scale in English and French. We also measured parental HPV knowledge and changes over time. An online questionnaire was administered in February (Time 1; T1) and November 2014 (Time 2; T2) to a nationally representative sample of Canadian parents of boys. Dimensionality, internal consistency and model fit were evaluated at both time points and separately in English and French sub-samples. Differences in knowledge scores were measured. Analyses were performed on 3117 participants at T1 and 1427 at T2. The 25-item HPV general knowledge and an 11-item HPV vaccination scale were unidimensional, showed high internal consistency (α>0.87, α>0.73) and had good model fit. Both general HPV and vaccine-specific knowledge significantly increased over time in both languages, but remained low at T2, with only about half of the items being answered correctly. Correct responses at T2 are best explained by correct responses at T1, with some small changes from 'Don't know' at T1 to correct at T2. The extended general and vaccine-specific knowledge scales are valid, reliable and comprehensive, and could be used among parents of boys, in both English and French. Educational interventions could target specific knowledge gaps and focus on providing information rather than correcting misconceptions
Gravitational lensing: a unique probe of dark matter and dark energy
I review the development of gravitational lensing as a powerful tool of the observational cosmologist. After the historic eclipse expedition organized by Arthur Eddington and Frank Dyson, the subject lay observationally dormant for 60 years. However, subsequent progress has been astonishingly rapid, especially in the past decade, so that gravitational lensing now holds the key to unravelling the two most profound mysteries of our Universe—the nature and distribution of dark matter, and the origin of the puzzling cosmic acceleration first identified in the late 1990s. In this non-specialist review, I focus on the unusual history and achievements of gravitational lensing and its future observational prospects
Comparing Galaxy Morphology at Ultraviolet and Optical Wavelengths
We have undertaken an imaging survey of 34 nearby galaxies in far-ultraviolet
(FUV, ~1500A) and optical (UBVRI) passbands to characterize galaxy morphology
as a function of wavelength. This sample, which includes a range of classical
Hubble types from elliptical to irregular with emphasis on spirals at low
inclination angle, provides a valuable database for comparison with images of
high-z galaxies whose FUV light is redshifted into the optical and near-
infrared bands. Ultraviolet data are from the UIT Astro-2 mission. We present
images and surface brightness profiles for each galaxy, and we discuss the
wavelength-dependence of morphology for different Hubble types in the context
of understanding high-z objects. In general, the dominance of young stars in
the FUV produces the patchy appearance of a morphological type later than that
inferred from optical images. Prominent rings and circumnuclear star formation
regions are clearly evident in FUV images of spirals, while bulges, bars, and
old, red stellar disks are faint to invisible at these short wavelengths.
However, the magnitude of the change in apparent morphology ranges from
dramatic in early--type spirals with prominent optical bulges to slight in
late-type spirals and irregulars, in which young stars dominate both the UV and
optical emission. Starburst galaxies with centrally concentrated, symmetric
bursts display an apparent ``E/S0'' structure in the FUV, while starbursts
associated with rings or mergers produce a peculiar morphology. We briefly
discuss the inadequacy of the optically-defined Hubble sequence to describe FUV
galaxy images and estimate morphological k-corrections, and we suggest some
directions for future research with this dataset.Comment: Accepted for publication in the ApJS. 15 pages, 17 JPEG figures, 10
GIF figures. Paper and full resolution figures available at
http://nedwww.ipac.caltech.edu/level5/Kuchinski/frames.htm
Identity and belonging in social learning groups : the importance of distinguishing social, operational and knowledge-related identity congruence
Collaborative learning has much to offer but not all learners participate fully and peer groups can be exclusive. The paper examines how belonging or 'congruence' in learning groups is related to identities of gender, age, ethnicity and socio-economic status. A study of student experiences of collaborative learning on three different blended learning courses illustrated how learners negotiate identity congruence with peer groups to belong and engage. An analytical framework that distinguishes social, operational and knowledge-related identity congruence has emerged. Contrary to received wisdom, the social aspect appears least important for learner engagement while knowledge-related identity congruence is fundamental. Some of the consequences of identity incongruence, particularly concerning gender and maturity, are discussed and the paper points towards the pedagogies which might enable identities of group members to shift so that collaborative learning can flourish
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