Concurrent muscle and bone deterioration in a murine model of cancer cachexia

Cachexia is defined as an excessive, involuntary loss of fat and lean tissue. We tested the validity of the Lewis lung carcinoma (LLC) as a model of cancer cachexia and examined its effect on the two major lean tissue components, skeletal muscle and bone. LLC cells (0.75 × 106) were injected into the left thigh of C57BL/6 mice. Control mice received an equal volume injection of growth media. Tumors were observed in all LLC-injected animals 21 and 25 days post inoculation. LLC-injected animals showed significant reductions in fat and lean mass despite having the same average daily caloric intake as media-treated mice. Global bone mineral density (BMD) had fallen by 5% and 6% in the LLC animals at 21 and 25 days, respectively, compared to a BMD increase of 5% in the 25-day media-treated animals. Extensor digitorum longus (EDL) muscles (isolated from the noninjected hindlimb) showed earlier and quantitatively greater losses in mass, physiological cross-sectional area (pCSA), and tetanic force compared to soleus muscles from the same hindlimb. By the 25th day post-LLC inoculation, EDL force/pCSA was reduced by 19% versus media treatment. This loss in specific force was not trivial as it accounted for about one-third of the reduction in EDL absolute force at this time point. Muscle strips dissected from the diaphragm of LLC mice also exhibited significant reductions in force/pCSA at day 25. We conclude that LLC is a valid model of cachexia that induces rapid losses in global BMD and in limb and respiratory muscle function

Semiquantum Chaos in the Double-Well

The new phenomenon of semiquantum chaos is analyzed in a classically regular double-well oscillator model. Here it arises from a doubling of the number of effectively classical degrees of freedom, which are nonlinearly coupled in a Gaussian variational approximation (TDHF) to full quantum mechanics. The resulting first-order nondissipative autonomous flow system shows energy dependent transitions between regular behavior and semiquantum chaos, which we monitor by Poincar\'e sections and a suitable frequency correlation function related to the density matrix. We discuss the general importance of this new form of deterministic chaos and point out the necessity to study open (dissipative) quantum systems, in order to observe it experimentally.Comment: LaTeX, 25 pages plus 7 postscript figures. Replaced figure 3 with a non-bitmapped versio

Octet baryon electromagnetic form factors in nuclear medium

We study the octet baryon electromagnetic form factors in nuclear matter using the covariant spectator quark model extended to the nuclear matter regime. The parameters of the model in vacuum are fixed by the study of the octet baryon electromagnetic form factors. In nuclear matter the changes in hadron properties are calculated by including the relevant hadron masses and the modification of the pion-baryon coupling constants calculated in the quark-meson coupling model. In nuclear matter the magnetic form factors of the octet baryons are enhanced in the low $Q^2$ region, while the electric form factors show a more rapid variation with $Q^2$. The results are compared with the modification of the bound proton electromagnetic form factors observed at Jefferson Lab. In addition, the corresponding changes for the bound neutron are predicted.Comment: Version accepted for publication in J.Phys. G. Few changes. 40 pages, 14 figures and 8 table

A comprehensive model of gain recovery due to unipolar electron transport after a short optical pulse in quantum cascade lasers

We have developed a comprehensive model of gain recovery due to unipolar electron transport after a short optical pulse in quantum cascade lasers (QCLs) that takes into account all the participating energy levels, including the continuum, in a device. This work takes into account the incoherent scattering of electrons from one energy level to another and quantum coherent tunneling from an injector level to an active region level or vice versa. In contrast to the prior work that only considered transitions to and from a limited number of bound levels, this work include transitions between all bound levels and between the bound energy levels and the continuum. We simulated an experiment of S. Liu et al., in which 438-pJ femtosecond optical pulses at the device’s lasing wavelength were injected into an In0:653Ga0:348As=In0:310Al0:690As QCL structure; we found that approximately 1% of the electrons in the bound energy levels will be excited into the continuum by a pulse and that the probability that these electrons will be scattered back into bound energy levels is negligible, 104. The gain recovery that is predicted is not consistent with the experiments, indicating that one or more phenomena besides unipolar electron transport in response to a short optical pulse play an important role in the observed gain recovery

Chromatin: a tunable spring at work inside chromosomes

This paper focuses on mechanical aspects of chromatin biological functioning. Within a basic geometric modeling of the chromatin assembly, we give for the first time the complete set of elastic constants (twist and bend persistence lengths, stretch modulus and twist-stretch coupling constant) of the so-called 30-nm chromatin fiber, in terms of DNA elastic properties and geometric properties of the fiber assembly. The computation naturally embeds the fiber within a current analytical model known as the ``extensible worm-like rope'', allowing a straightforward prediction of the force-extension curves. We show that these elastic constants are strongly sensitive to the linker length, up to 1 bp, or equivalently to its twist, and might locally reach very low values, yielding a highly flexible and extensible domain in the fiber. In particular, the twist-stretch coupling constant, reflecting the chirality of the chromatin fiber, exhibits steep variations and sign changes when the linker length is varied. We argue that this tunable elasticity might be a key feature for chromatin function, for instance in the initiation and regulation of transcription.Comment: 38 pages 15 figure

A dual process account of creative thinking

This article explicates the potential role played by type 1 thinking (automatic, fast) and type 2 thinking (effortful, logical) in creative thinking. The relevance of Evans's (2007) models of conflict of dual processes in thinking is discussed with regards to creative thinking. The role played by type 1 thinking and type 2 thinking during the different stages of creativity (problem finding and conceptualization, incubation, illumination, verification and dissemination) is discussed. It is proposed that although both types of thinking are active in creativity, the extent to which they are active and the nature of their contribution to creativity will vary between stages of the creative process. Directions for future research to test this proposal are outlined; differing methodologies and the investigation of different stages of creative thinking are discussed. © Taylor & Francis Group, LLC

Evaluating Atlantic bluefin tuna harvest strategies that use conventional genetic tagging data

An individual tagging model was implemented within the spatial, seasonal, multi-stock, multi-fleet operating models of the peer-reviewed Management Strategy Evaluation (MSE) framework for Atlantic bluefin tuna to evaluate the benefits of a harvest strategy that utilizes conventional gene tagging. A multi-year Brownie estimator was developed to test the accuracy and precision of exploitation rate estimates arising from gene tagging programs with various scenarios for spatial release distribution, release numbers and fishery exploitation rates. Harvest strategies that used the Brownie estimator were tested to evaluate yield and resource conservation performance relative to idealized management using perfect information. For the eastern stock, releasing 1,000 fish throughout the Atlantic and genotyping 27% of all landed fish at an estimated cost of US$2M was sufficient to obtain estimates of exploitation rate with a coefficient of variation of 20$2.5M. Harvest strategies using the gene tagging data provided expected yield and resource conservation performance that was not substantially lower than a harvest strategy assuming using perfect information regarding vulnerable biomass. Reducing the number of releases most strongly affected the worst-case ‘lower-tail’ outcomes for West area yield and eastern stock biomass. Conventional gene tagging harvest strategies offer a promising basis for calculating management advice for Atlantic bluefin tuna that may be cheaper, simpler, and more robust than the current conventional stock assessment paradigm

ROBERT BURNS AND FRIENDS essays by W. Ormiston Roy Fellows presented to G. Ross Roy

Robert Burns & Friends essays by W. Ormiston Roy Fellows presented to G. Ross Roy edited by Patrick Scott and Kenneth Simpson This volume of essays about the Scottish poet Robert Burns (1759-1796) pays tribute to the distinguished Burns scholar G. Ross Roy. Subjects covered include writers who influenced Burns; aspects of the writing of Burns and that of his friends and contemporaries; and Burns\u27s influence on later writers. The volume also includes essays on Ross Roy\u27s own accomplishments and on the Burns collection he built (now at the University of South Carolina), together with a checklist of his published writings. G. Ross Roy, Distinguished Professor Emeritus of English and Comparative Literature, founded the journal Studies in Scottish Literature in 1963, and as its editor for nearly fifty years he has had a central role in establishing international academic recognition for the field. His own scholarly work includes the standard Letters of Robert Burns (2 vols., Clarendon Press, 1985). His contributions to Scottish literature have earned him honorary doctorates from the Universities of Edinburgh (2002) and Glasgow (2009). The contributors are all former W. Ormiston Roy Visiting Fellows at the University of South Carolina. This book is also available in a print edition (ISBN: 978-1439270974) through the usual on-line vendors. It is not available for direct purchase from the editors or the University of South Carolina