73,413 research outputs found
Eight unique basal bodies in the multi-flagellated diplomonad Giardia lamblia.
Giardia lamblia is an intestinal parasitic protist that causes significant acute and chronic diarrheal disease worldwide. Giardia belongs to the diplomonads, a group of protists in the supergroup Excavata. Diplomonads are characterized by eight motile flagella organized into four bilaterally symmetric pairs. Each of the eight Giardia axonemes has a long cytoplasmic region that extends from the centrally located basal body before exiting the cell body as a membrane-bound flagellum. Each basal body is thus unique in its cytological position and its association with different cytoskeletal features, including the ventral disc, axonemes, and extra-axonemal structures. Inheritance of these unique and complex cytoskeletal elements is maintained through basal body migration, duplication, maturation, and their subsequent association with specific spindle poles during cell division. Due to the complex composition and inheritance of specific basal bodies and their associated structures, Giardia may require novel basal body-associated proteins. Thus, protists such as Giardia may represent an undiscovered source of novel basal body-associated proteins. The development of new tools that make Giardia genetically tractable will enable the composition, structure, and function of the eight basal bodies to be more thoroughly explored
Quantum signatures of breather-breather interactions
The spectrum of the Quantum Discrete Nonlinear Schr\"odinger equation on a
periodic 1D lattice shows some interesting detailed band structure which may be
interpreted as the quantum signature of a two-breather interaction in the
classical case. We show that this fine structure can be interpreted using
degenerate perturbation theory.Comment: 4 pages, 4 fig
NMR Probing Spin Excitations in the Ring-Like Structure of a Two-Subband System
Resistively detected nuclear magnetic resonance (NMR) is observed inside the
ring-like structure, with a quantized Hall conductance of 6e^2/h, in the phase
diagram of a two subband electron system. The NMR signal persists up to 400 mK
and is absent in other states with the same quantized Hall conductance. The
nuclear spin-lattice relaxation time, T1, is found to decrease rapidly towards
the ring center. These observations are consistent with the assertion of the
ring-like region being a ferromagnetic state that is accompanied by collective
spin excitations.Comment: 4 pages, 4 figure
Toward the Integration of Economics and Outdoor Recreation Management
The general theme of this bulletin is that improved management of
public-sector recreational resources is a multidisciplinary task. To this
end, we attempt to integrate elements of outdoor recreation management
theory and economics. The bulletin is written for both resource managers
and researchers. For the former, our intent is to emphasize the importance
of being aware of economic implications-at least conceptually-of
management actions that influence the character and availability of recreational
opportunities. To researchers involved in developing recreation
management theory, we draw attention to the parallel between recreation
management theory and the traditional managerial economic model
of the firm. To economists, particularly those involved in developing
and applying nonmarket valuation techniques, we draw attention to the
types of decisions faced by resource managers.
We argue that the most important resource allocation issues are of
the incremental variety, so nonmarket valuation should also yield incremental
values. These values alone, however, are not sufficient
economic input into rational public choice analysis. The missing link ,
or nexus, between outdoor recreation management theory and economic
analysis is the integration of supply and demand, as called for by traditional
managerial economics. Collaborative research to develop recreation
supply response functions akin to agricultural production functions
is an essential step that is missing from both literatures. Theoretical and
applied work assume greater practical importance if they feed information
into this broadened framework. It is our hope that this bulletin will
bring the disciplines closer to that realization
Incoherence of Bose-Einstein condensates at supersonic speeds due to quantum noise
We calculate the effect of quantum noise in supersonic transport of
Bose-Einstein condensates. When an obstacle obstructs the flow of atoms,
quantum fluctuations cause atoms to be scattered incoherently into random
directions. This suppresses the propagation of Cherenkov radiation, creating
quantum turbulence and a crescent of incoherent atoms around the obstacle. We
observe similar dynamics if the BEC is stirred by a laser beam: crescents of
incoherent atoms are emitted from the laser's turning-points. Finally, we
investigate supersonic flow through a disordered potential, and find that the
quantum fluctuations generate an accumulation of incoherent atoms as the
condensate enters the disorder.Comment: 6 pages, 5 figure
Student perceptions of their autonomy at University
© 2017, The Author(s). Learner autonomy is a primary learning outcome of Higher Education in many countries. However, empirical evaluation of how student autonomy progresses during undergraduate degrees is limited. We surveyed a total of 636 studentsâ self-perceived autonomy during a period of two academic years using the Autonomous Learning Scale. Our analysis suggests that students do not perceive themselves as being any more autonomous as they progress through University. Given the relativity of self-perception metrics, we suggest that our results evince a âred queenâ effect. In essence, as course expectations increase with each year, each studentâs self-perceived autonomy relative to their ideal remains constant; we term this the âmoving goalpostâ hypothesis. This article corroborates pedagogical literature suggesting that providing students with opportunities to act autonomously and develop confidence is key to developing graduates who have the independence that they need in order to be successful in the workplace
Extent of regretted sexual intercourse among young teenagers in Scotland: a cross sectional survey
No abstract available
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