366 research outputs found
Report from the Field: Multi-cultural Dialogue and Transformative Learning in Arts & Minds Programs at The Studio Museum in Harlem
This paper presents a report from the field of museum education programs for people with Alzheimer’s disease and related dementias (ADRD) and their caregivers. Research is beginning to document the impact of museums on the cognitive and emotional health of people with dementia (PWD) and those who care for them. At the Studio Museum in Harlem, Arts Minds programs have created a dynamic learning environment for the very forgetful through dialogic interpretation of art and expressive art making. The stories recounted here reveal the powerful potential of multi-cultural dialogue in the museum space to create transformative learning experiences for participants and educators alike
Polymer Adsorption on Disordered Substrate
We analyze the recently proposed "pattern-matching" phase of a Gaussian
random heteropolymer adsorbed on a disordered substrate [S. Srebnik, A.K.
Chakraborty and E.I. Shakhnovich, Phys. Rev. Lett. 77, 3157 (1996)]. By mapping
the problem to that of a directed homopolymer in higher-dimensional random
media, we show that the pattern-matching phase is asymptotically weakly
unstable, and the large scale properties of the system are given by that of an
adsorbed homopolymer.Comment: 5 pages, RevTeX, text also available at http://matisse.ucsd.edu/~hw
Dynamics of Multidimensional Secession
We explore a generalized Seceder Model with variable size selection groups
and higher dimensional genotypes, uncovering its well-defined mean-field
limiting behavior. Mapping to a discrete, deterministic version, we pin down
the upper critical size of the multiplet selection group, characterize all
relevant dynamically stable fixed points, and provide a complete analytical
description of its self-similar hierarchy of multiple branch solutions.Comment: 4 pages, 4 figures, PR
Universal correlators and distributions as experimental signatures of 2+1 Kardar-Parisi-Zhang growth
We examine height-height correlations in the transient growth regime of the
2+1 Kardar-Parisi-Zhang (KPZ) universality class, with a particular focus on
the {\it spatial covariance} of the underlying two-point statistics,
higher-dimensional analog of the 1+1 KPZ Class Airy process. Making
comparison to AFM kinetic roughening data in 2d organic thin films, we use our
universal 2+1 KPZ spatial covariance to extract key scaling parameters for this
experimental system. Additionally, we explore the i) height, ii) local
roughness, and iii) extreme value distributions characteristic of these
oligomer films, finding compelling agreement in all instances with our
numerical integration of the KPZ equation itself. Finally, investigating
nonequilibrium relaxation phenomena exhibited by 2+1 KPZ Class models, we have
unearthed a universal KPZ ageing kinetics. In experiments with ample data in
the time domain, our 2+1 KPZ Euler {\it temporal covariance} will allow a
quick, independent estimate of the central KPZ scaling parameter.Comment: 6 Pages, 5 Figure
Directed polymers in random media under confining force
The scaling behavior of a directed polymer in a two-dimensional (2D) random
potential under confining force is investigated. The energy of a polymer with
configuration is given by H\big(\{y(x)\}\big) = \sum_{x=1}^N \exyx
+ \epsilon \Wa^\alpha, where is an uncorrelated random potential
and \Wa is the width of the polymer. Using an energy argument, it is
conjectured that the radius of gyration and the energy fluctuation
of the polymer of length in the ground state increase as
and respectively with and for . A
novel algorithm of finding the exact ground state, with the effective time
complexity of \cO(N^3), is introduced and used to confirm the conjecture
numerically.Comment: 9 pages, 7 figure
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Structure and Function of a Transposon-Encoded CRISPR-Cas System
CRISPR-Cas defense systems are employed by their hosts to prevent parasitization by mobile genetic elements. The discovery of nuclease-deficient CRISPR-Cas systems contained within transposon ends suggested a repurposing of the contained defense system. One such Type I-F3 CRISPR-Cas system was found inside Tn6677, a Tn7-like transposon within the genome of a Vibrio cholerae strain. Tn6677 requires coordination between the contained CRISPR-Cas system and the transposition proteins for effective transposition. Isolation of this system, and reduction to its minimal components, enabled RNA-guided integration of donor DNA in Escherichia coli. Base-pairing interactions between the user-specified CRISPR RNA and the target sequence precede the integration of donor DNA approximately 49-bp downstream of the end of the target sequence. This system is specific regardless of the supplied RNA guide, and successfully integrates donors of different lengths. The donor DNA is indicated by flanking cognate transposon end sequences. While clearly functional, the mechanism by which the transposition proteins and the CRISPR-Cas proteins interact remained unclear. To this end we purified the multi-protein RNA-guided DNA binding complex (Cascade) from the transposon-encoded minimal I-F3 CRISPR-Cas system in complex with the transposition protein TniQ. De novo modeling revealed the unexpected dimerization of TniQ, and its location within the complex, bound to the Cas6-end of the transposon-encoded Type I-F3 Cascade. Additional models obtained from DNA-bound structures of the complex demonstrate initial steps in target binding alongside novel conformations of Cascade subunits. This work reveals the mechanism by which the Tn6677 components guide integration and will enable rational engineering of these systems for further experimentation and tool development
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