405 research outputs found
Magnetic Properties of the low dimensional spin system (VO)PO: ESR and susceptibility
Experimental results on magnetic resonance (ESR) and magnetic susceptibility
are given for single crystalline (VO)PO. The crystal growth
procedure is briefly discussed. The susceptibility is interpreted numerically
using a model with alternating spin chains. We determine =51 K and
=0.2. Furthermore we find a spin gap of meV from our ESR
measurements. Using elastic constants no indication of a phase transition
forcing the dimerization is seen below 300 K.Comment: 7 pages, REVTEX, 7 figure
Unterschiede in Futteraufnahmeverhalten und Energieumsatz zwischen âgenetisch schlankenâ und âgenetisch adipösenâ Katern
Involvement of mossy cells in sharp wave-ripple activity in vitro
The role of mossy cells (MCs) of the hippocampal dentate area has long remained mysterious. Recent research has begun to unveil their significance in spatial computation of the hippocampus. Here, we used an in vitro model of sharp wave-ripple complexes (SWRs), which contribute to hippocampal memory formation, to investigate MC involvement in this fundamental population activity. We find that a significant fraction of MCs (~47%) is recruited into the active neuronal network during SWRs in the CA3 area. Moreover, MCs receive pronounced, ripple-coherent, excitatory and inhibitory synaptic input. Finally, we find evidence for SWR-related synaptic activity in granule cells that is mediated by MCs. Given the widespread connectivity of MCs within and between hippocampi, our data suggest a role for MCs as a hub functionally coupling the CA3 and the DG during ripple-associated computations
The 1991 Field Evaluation of Herbicides on Small Fruit, Vegetables and Ornamental Crops
The establishment of this field-testing procedure provides the chemical industry, through its partial support, and the Arkansas Experiment Station the opportunity to evaluate herbicide performance on small fruit, vegetable and ornamental crops grown under Arkansas conditions. This report also provides a means for disseminating information to interested people and public-service weed scientists
Analytical Bethe Ansatz for closed and open gl(n)-spin chains in any representation
We present an "algebraic treatment" of the analytical Bethe Ansatz. For this
purpose, we introduce abstract monodromy and transfer matrices which provide an
algebraic framework for the analytical Bethe Ansatz. It allows us to deal with
a generic gl(n)-spin chain possessing on each site an arbitrary
gl(n)-representation. For open spin chains, we use the classification of the
reflection matrices to treat all the diagonal boundary cases. As a result, we
obtain the Bethe equations in their full generality for closed and open spin
chains. The classifications of finite dimensional irreducible representations
for the Yangian (closed spin chains) and for the reflection algebras (open spin
chains) are directly linked to the calculation of the transfer matrix
eigenvalues. As examples, we recover the usual closed and open spin chains, we
treat the alternating spin chains and the closed spin chain with impurity
Rhythmic dynamics and synchronization via dimensionality reduction : application to human gait
Reliable characterization of locomotor dynamics of human walking is vital to understanding the neuromuscular control of human locomotion and disease diagnosis. However, the inherent oscillation and ubiquity of noise in such non-strictly periodic signals pose great challenges to current methodologies. To this end, we exploit the state-of-the-art technology in pattern recognition and, specifically, dimensionality reduction techniques, and propose to reconstruct and characterize the dynamics accurately on the cycle scale of the signal. This is achieved by deriving a low-dimensional representation of the cycles through global optimization, which effectively preserves the topology of the cycles that are embedded in a high-dimensional Euclidian space. Our approach demonstrates a clear advantage in capturing the intrinsic dynamics and probing the subtle synchronization patterns from uni/bivariate oscillatory signals over traditional methods. Application to human gait data for healthy subjects and diabetics reveals a significant difference in the dynamics of ankle movements and ankle-knee coordination, but not in knee movements. These results indicate that the impaired sensory feedback from the feet due to diabetes does not influence the knee movement in general, and that normal human walking is not critically dependent on the feedback from the peripheral nervous system
Translation, cross-cultural adaptation, and validation of the Portuguese version of the Rotterdam Elderly Pain Observation Scale (REPOS)
Productive restructuring and the reallocation of work and employment: a survey of the ânewâ forms of social inequality
O propĂłsito do presente artigo consiste
em questionar a inevitabilidade dos processos de
segmentação e precarização das relaçÔes de trabalho
e emprego, responsåveis pela inscrição de
ânovasâ formas de desigualdade social que alicerçam
o actual modelo de desenvolvimento das economias
e sociedades. Visa-se criticar os limites da
lĂłgica econĂŽmica e financeira, de contornos globais,
que configuram um ânovo espĂrito do capitalismoâ,
ou seja, uma espécie de divinização da
ordem natural das coisas. ImpÔe-se fazer, por isso,
um pĂ©riplo analĂtico pelas transformaçÔes em curso
no mercado de trabalho, acompanhado pela vigilĂąncia
epistemolĂłgica que permita enquadrar e
relativizar as (di)visÔes neoliberais e teses tecnodeterministas
dominantes. A perspectivação de cenårios
sobre o futuro do trabalho encerrarĂĄ este
périplo, permitindo-nos alertar para os condicionalismos
histĂłrico-temporais, para a urgĂȘncia de
se desocultar o que de ideolĂłgico e polĂtico existe
nas actuais lógicas de racionalização e para os
processos de ressimbolização do trabalho e emprego
enquanto âexperiĂȘncia social centralâ na
contemporaneidade.The scope of this paper is to question
the inevitability of the processes of segmentation
and increased precariousness of the relations
of labor and employment, which are responsible
for the introduction of ânewâ forms of
social inequality that underpin the current model
of development of economies and societies. It
seeks to criticize the limits of global financial and
economic logic, which constitute a ânew spirit of
capitalism,â namely a kind of reverence for the
natural order of things. It is therefore necessary
to conduct an analytical survey of the ongoing
changes in the labor market, accompanied by epistemological
vigilance which makes it possible to
see neoliberal (di)visions and dominant technodeterministic
theses in context. The enunciation
of scenarios on the future of work will conclude
this survey and will make it possible to draw attention
to both the historical and temporal constraints
and to the urgent need to unveil what is
ideological and political in the prevailing logic of
rationalization and processes to reinstate work
and employment as a âcentral social experienceâ
in contemporary times
Reinforcement versus Fluidization in Cytoskeletal Mechanoresponsiveness
Every adherent eukaryotic cell exerts appreciable traction forces upon its substrate. Moreover, every resident cell within the heart, great vessels, bladder, gut or lung routinely experiences large periodic stretches. As an acute response to such stretches the cytoskeleton can stiffen, increase traction forces and reinforce, as reported by some, or can soften and fluidize, as reported more recently by our laboratory, but in any given circumstance it remains unknown which response might prevail or why. Using a novel nanotechnology, we show here that in loading conditions expected in most physiological circumstances the localized reinforcement response fails to scale up to the level of homogeneous cell stretch; fluidization trumps reinforcement. Whereas the reinforcement response is known to be mediated by upstream mechanosensing and downstream signaling, results presented here show the fluidization response to be altogether novel: it is a direct physical effect of mechanical force acting upon a structural lattice that is soft and fragile. Cytoskeletal softness and fragility, we argue, is consistent with early evolutionary adaptations of the eukaryotic cell to material properties of a soft inert microenvironment
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