Requirements for contractility in disordered cytoskeletal bundles

Actomyosin contractility is essential for biological force generation, and is well understood in highly organized structures such as striated muscle. Additionally, actomyosin bundles devoid of this organization are known to contract both in vivo and in vitro, which cannot be described by standard muscle models. To narrow down the search for possible contraction mechanisms in these systems, we investigate their microscopic symmetries. We show that contractile behavior requires non-identical motors that generate large enough forces to probe the nonlinear elastic behavior of F-actin. This suggests a role for filament buckling in the contraction of these bundles, consistent with recent experimental results on reconstituted actomyosin bundles.Comment: 10 pages, 6 figures; text shortene

Acute stress affects peripersonal space representation in cortisol stress responders.

Peripersonal space is the representation of the space near the body. It is implemented by a dedicated multisensory-motor network, whose purpose is to predict and plan interactions with the environment, and which can vary depending on environmental circumstances. Here, we investigated the effect on the PPS representation of an experimentally induced stress response and compared it to a control, non-stressful, manipulation. We assessed PPS representation in healthy humans, before and after a stressful manipulation, by quantifying visuotactile interactions as a function of the distance from the body, while monitoring salivary cortisol concentration. While PPS representation was not significantly different between the control and experimental group, a relation between cortisol response and changes in PPS emerged within the experimental group. Participants who showed a cortisol stress response presented enhanced visuotactile integration for stimuli close to the body and reduced for far stimuli. Conversely, individuals with a less pronounced cortisol response showed a reduced difference in visuotactile integration between the near and the far space. In our interpretation, physiological stress resulted in a freezing-like response, where multisensory-motor resources are allocated only to the area immediately surrounding the body

Comparison of techniques for computing shell-model effective operators

Different techniques for calculating effective operators within the framework of the shell model using the same effective interaction and the same excitation spaces are presented. Starting with the large-basis no-core approach, we compare the time-honored perturbation-expansion approach and a model-space truncation approach. Results for the electric quadrupole and magnetic dipole operators are presented for $^6$Li. The convergence trends and dependence of the effective operators on differing excitation spaces and Pauli Q-operators is studied. In addition, the dependence of the electric-quadrupole effective charge on the harmonic-oscillator frequency and the mass number, for A=5,6, is investigated in the model-space truncation approach.Comment: 18 pages. REVTEX. 4 PostScript figure

The significance of lifeworld and the case of hospice

Questions on what it means to live and die well are raised and discussed in the hospice movement. A phenomenological lifeworld perspective may help professionals to be aware of meaningful and important dimensions in the lives of persons close to death. Lifeworld is not an abstract philosophical term, but rather the opposite. Lifeworld is about everyday, common life in all its aspects. In the writings of Cicely Saunders, known as the founder of the modern hospice movement, facets of lifeworld are presented as important elements in caring for dying patients. Palliative care and palliative medicine today are, in many ways, replacing hospices. This represents not only a change in name, but also in the main focus. Hospice care was originally very much about providing support and comfort for, and interactions with the patients. Improved medical knowledge today means improved symptomatic palliation, but also time and resources spent in other ways than before. Observations from a Nordic hospice ward indicate that seriously ill and dying persons spend much time on their own. Different aspects of lifeworld and intersubjectivity in the dying persons’ room is presented and discussed