558 research outputs found
Visualization of SpoVAEa Protein Dynamics in Dormant Spores of <i>Bacillus cereus</i> and Dynamic Changes in Their Germinosomes and SpoVAEa during Germination
Bacillus cereus spores, like most Bacillus spores, can survive for years and germinate when their surroundings become suitable, and germination proteins play an important role in the initiation of germination. Because germinated spores lose the extreme resistance of dormant spores, information on the function of germination proteins could be useful in developing new strategies to control B. cereus spores. Prior work has shown that (i) the channel protein SpoVAEa exhibits high-frequency movement in the outer leaflet of the inner membrane (IM) in dormant B. subtilis spores and (ii) the formation of the foci termed germinosomes between two germination proteins, the germinant receptor GerR and the scaffold protein GerD, in developing B. cereus spores is slower than foci formation by GerR and GerD individually. However, the movement dynamics of SpoVAEa in B. cereus spores, and the behavior of the germinosome upon B. cereus spore germination, are not known. In this study, we found that SpoVAEa fluorescent foci in dormant B. cereus spores move on the IM, but slower than in B. subtilis spores, and they likely co-localize transiently with GerD-mScarlet-I in the germinosome. Our results further indicate that (i) the expression of GerR-SGFP2 and SpoVAEa-SGFP2 with GerD-mScarlet-I from a plasmid leads to more heterogeneity and lower efficiency of spore germination in B. cereus, and (ii) germinosome foci observed by Fluorescence resonance energy transfer (FRET) between GerR-SGFP2 and GerD-mScarlet-I can be lost soon after the spore-phase transition. However, this is not always the case, as some GerR-SGFP2 and GerD-mScarlet-I foci continued to exist, co-localize, and even show a weak FRET signal. These data highlight the heterogeneous behavior of spore germination protein complexes and indicate that some complexes may persist beyond the initiation of germination. IMPORTANCE Bacillus cereus is commonly present in soil and infects humans via contaminated food. In this study, we used B. cereus spores to investigate the movement of the spore-specific inner membrane (IM) channel protein SpoVAEa, the interaction between SpoVAEa and the germinosome scaffold protein GerD, and the dynamics of germinosomes with GerR and GerD in spore germination. Our results expand upon observations of interactions between specific B. cereus spore germination proteins, in particular the GerR germinant receptor A, B, and C subunits and GerD, as well as those between SpoVAEa and GerD. The approaches used in this work could also be used to examine the interactions between GerD and SpoVAEa and other germination proteins in spores of other Bacillus species
Many--Particle Correlations in Relativistic Nuclear Collisions
Many--particle correlations due to Bose-Einstein interference are studied in
ultrarelativistic heavy--ion collisions. We calculate the higher order
correlation functions from the 2--particle correlation function by assuming
that the source is emitting particles incoherently. In particular
parametrizations of and relations between longitudinal, sidewards, outwards and
invariant radii and corresponding momenta are discussed. The results are
especially useful in low statistics measurements of higher order correlation
functions. We evaluate the three--pion correlation function recently measured
by NA44 and predict the 2--pion--2--kaon correlation function. Finally, many
particle Coulomb corrections are discussed.Comment: 5 corrected misprints, 14 pages, revtex, epsfig, 6 figures included,
manuscript also available at http://www.nbi.dk/~vischer/publications.htm
Nucleation of Quark--Gluon Plasma from Hadronic Matter
The energy densities achieved during central collisions of large nuclei at
Brookhaven's AGS may be high enough to allow the formation of quark--gluon
plasma. Calculations based on relativistic nucleation theory suggest that rare
events, perhaps one in every 10 or 10, undergo the phase transition.
Experimental ramifications may include an enhancement in the ratio of pions to
baryons, a reduction in the ratio of deuterons to protons, and a larger source
size as seen by hadron interferometry.Comment: 22 pages, 7 figures available upon request, NUC--MINN--94/5--
Scattering in the Presence of Electroweak Phase Transition Bubble Walls
We investigate the motion of fermions in the presence of an electro\-weak
phase transition bubble wall. We derive and solve the Dirac equation for such
fer\-mions, and compute the transmission and reflection coefficients for
fermions traveling from the symmetric to the asymmetric phases separated by the
domain wall.Comment: TPI--MINN--54, NUC--MINN--93/30--T, UMN--TH--1226/93, LaTex, 29 page
Empathy, engagement, entrainment: the interaction dynamics of aesthetic experience
A recent version of the view that aesthetic experience is based in empathy as inner
imitation explains aesthetic experience as the automatic simulation of actions,
emotions, and bodily sensations depicted in an artwork by motor neurons in the brain. Criticizing the simulation theory for committing to an erroneous concept of empathy and failing to distinguish regular from aesthetic experiences of art, I advance an alternative, dynamic approach and claim that aesthetic experience is enacted and skillful, based in the recognition of othersâ experiences as distinct from oneâs own. In combining insights from mainly psychology, phenomenology, and cognitive science, the dynamic approach aims to explain the emergence of aesthetic experience in terms of the reciprocal interaction between viewer and artwork. I argue that aesthetic experience emerges by participatory sense-making and revolves around movement as a means for creating meaning. While entrainment merely plays a preparatory part in this, aesthetic engagement constitutes the phenomenological side of coupling to an artwork and provides the context for exploration, and eventually for moving, seeing, and feeling with art. I submit that aesthetic experience emerges from bodily and emotional engagement with works of art via the complementary processes of the perceptionâaction and motionâemotion loops. The former involves the embodied
visual exploration of an artwork in physical space, and progressively structures and organizes visual experience by way of perceptual feedback from body movements made in response to the artwork. The latter concerns the movement qualities and shapes of implicit and explicit bodily responses to an artwork that cue emotion and thereby modulate over-all affect and attitude. The two processes cause the viewer to bodily and emotionally move with and be moved by individual works of art, and consequently to recognize another psychological orientation than her own, which explains how art can cause feelings of insight or awe and disclose aspects of life that are unfamiliar or novel to the viewer
Louis I. Kahn and Richard Kelly: collaborative design in creation of the luminous environment
As one of the most prominent architects of the twentieth century, Louis I. Kahn aspired to use natural light to shape his architecture. The lighting designer Richard Kelly, one of his close collaborators, had significant influence on modern architectural lighting design in the twentieth century. Kahn and Kelly designed the luminous environments in three art-gallery and museum buildings, The Yale University Art Gallery, the Kimbell Art Museum and the Yale Center for British Art. Collaboration between the architect and the lighting designer resulted in well-resolved lighting solutions. This research investigated the collaboration between Louis I. Kahn and Richard Kelly from both theoretical and pragmatic perspectives. In terms of the theoretical perspective, a detailed overview of their collaborative work is provided through literature review. In terms of the pragmatic perspective, the background of their cooperation and the technical details are presented. In addition, daylighting performance analysis of these three buildings through digital modelling was undertaken. This study found that the lighting design solutions produced together by Louis I. Kahn and Richard Kelly, especially the way of using daylight, have had significant impact on architectural space and the luminous environment. More importantly, this kind of collaborative working method could provide a useful reference and guidance for contemporary architecture and lighting design
Geometry and kinematics for a spherical-base integrated parallel mechanism
Parallel mechanisms, in general, have a rigid base and a moving platform connected by several limbs. For achieving higher mobility and dexterity, more degrees of freedom are introduced to the limbs. However, very few researchers focus on changing the design of the rigid base and making it foldable and reconfigurable to improve the performance of the mechanism. Inspired by manipulating an object with a metamorphic robotic hand, this paper presents for the first time a parallel mechanism with a reconfigurable base. This novel spherical-base integrated parallel mechanism has an enlarged workspace compared with traditional parallel manipulators. Evolution and structure of the proposed parallel mechanism is introduced and the geometric constraint of the mechanism is investigated based on mechanism decomposition. Further, kinematics of the proposed mechanism is reduced to the solution of a univariate polynomial of degree 8. Moreover, screw theory based Jacobian is presented followed by the velocity analysis of the mechanism
Resoundings of the flesh: Caring for others by way of âsecond personâ perspectivity
In bringing ourselves to the encounter with the experience of others, we bring our bodies with usâand, in doing so, we are able to resonate not only intellectually but also empathically with the other's experiences and expressions (which are given to us both verbally and nonverbally). In remaining faithful to our foundations in phenomenology (Husserl, Heidegger, Merleau-Ponty, and Levinas), we shall talk about taking notice of others from within the relational âexchangeâ and reflect upon what, precisely, are the experientially given âaffairsâ to which Husserl invited us to return. Our interest begins with the other's âfirst personâ experience, but since we cannot access this directly, we must rely on the resonance we find within ourselves, within our own lived bodies, when we are addressed by the other, whether in word or in gesture. I am wondering what the other is experiencing and all my powers of perception are driven toward this other, whose first person experience remains just out of reach and accessible only insofar as I have this capacity for a deeper âbodily feltâ awareness in which the other's experience takes possession of me. Merleau-Ponty's notion of bearing âwitnessâ to behavior is useful in illuminating this âsecond personâ perspective, which takes its point of departure from Husserl's (1910â1911) intersubjective reduction, by means of which we âparticipate in the other's positingâ (1952/1989, emphasis added) and thereby grasp the meaning of the other's expression. Ultimately, the intuitive talent of the caring professional will be shown to reside in his or her being able to move beyond what the other is able to say to a more deeply felt attunement to what is being revealed to us in the other's presence. Applications to patient care are discussed
Shared decision making in designing new healthcare environmentsâtime to begin improving quality
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