Energy Storage in a Hamiltonian System in Partial Contact with a Heat Bath

To understand the mechanism allowing for the long-term storage of excess energy in proteins, we study a Hamiltonian system consisting of several coupled pendula in partial contact with a heat bath. It is found that energy storage is possible when the motion of each pendulum switches between oscillatory (vibrational) and rotational (phase-slip) modes. The storage time increases almost exponentially to the square root of the injected energy. The relevance of our mechanism to protein motors is discussed.Comment: 8 pages, 4 figures, to appear in J.Phys.Soc.Jp

The factors associated with pain severity in patients with knee osteoarthritis vary according to the radiographic disease severity: a cross-sectional study

SummaryObjectivesKnee osteoarthritis (OA) pain is suggested to be associated with inflammation and detrimental mechanical loading across the joint. In this cross-sectional study, we simultaneously examined the inflammation and alignment of the lower limb and examined how the pain components varied depending on the disease progression.DesignOne-hundred sixty female medial type of early- [n = 74 in Kellgren–Lawrence (K/L) 2] to advanced-stage (n = 96 in K/L >2) knee OA subjects (70.5 years on average) were enrolled. Knee pain was evaluated using a pain visual analog scale (VAS) and the pain-related subcategory of the Japanese Knee Osteoarthritis Measure (JKOM-pain). The serum interleukin (sIL)-6 level reflecting synovitis, and the high sensitivity C-reactive protein (hs-CRP) level were measured to evaluate the severity of inflammation. The anatomical axis angle (AAA) was measured as an alignment index. The β-coefficient was estimated after adjusting for age and the body mass index (BMI) using a multiple linear regression analysis.ResultsMultiple linear regression analyses showed that the sIL-6 levels, but not AAA, associated with the pain VAS [β = 10.77 (95% confidence interval (CI): 4.14–17.40), P < 0.01] and JKOM-pain scores [β = 3.19 (95% CI: 1.93–4.44), P < 0.001] in the early stage. Conversely, AAA, but not the sIL-6 levels, was found to be associated with the pain VAS [β = −1.29 (95% CI: −2.51 to −0.08), P < 0.05] and JKOM-pain scores [β = −0.49 (95% CI: −0.82 to −0.16), P < 0.01] in the advanced stage.ConclusionsThe presence of a higher level of sIL-6 and the varus alignment of the joint is associated with pain in early- and advanced-stage knee OA patients, respectively

The degeneration and destruction of femoral articular cartilage shows a greater degree of deterioration than that of the tibial and patellar articular cartilage in early stage knee osteoarthritis: a cross-sectional study

SummaryObjectiveThe aim of the present study was to examine whether the degenerative and morphological changes of articular cartilage in early stage knee osteoarthritis (OA) occurred equally for both femoral- and tibial- or patellar- articular cartilage using magnetic resonance imaging (MRI)-based analyses.DesignThis cross-sectional study was approved by the ethics committee of our university. Fifty patients with early stage painful knee OA were enrolled. The patients underwent 3.0 T MRI on the affected knee joint. Healthy volunteers who did not show MRI-based OA changes were also recruited as controls (n = 19). The degenerative changes of the articular cartilage were quantified by a T2 mapping analysis, and any structural changes were conducted using Whole Organ Magnetic Resonance Imaging Score (WORMS) technique.ResultsAll patients showed MRI-detected OA morphological changes. The T2 values of femoral condyle (FC) (P < 0.0001) and groove (P = 0.0001) in patients with early stage knee OA were significantly increased in comparison to those in the control, while no significant differences in the T2 values of patellar and tibial plateau (TP) were observed between the patients and the control. The WORMS cartilage and osteophyte scores of the femoral articular cartilage were significantly higher than those in the patellar- (P = 0.001 and P = 0.007, respectively) and tibial- (P = 0.0001 and P < 0.0001, respectively) articular cartilage in the patients with early stage knee OA.ConclusionsThe degradation and destruction of the femoral articular cartilage demonstrated a greater degree of deterioration than those of the tibial- and patellar- articular cartilage in patients with early stage knee OA

A comprehensive and comparative study of elastic electron scattering from OCS and CS2 in the energy region from 1.2 to 200 eV

We report absolute differential cross sections (DCSs) for elastic electron scattering from OCS (carbonyl sulphide) and CS₂ (carbon disulphide) in the impact energy range of 1.2-200 eV and for scattering angles from 10° to 150°. Above 10 eV, the angular distributions are found to agree quite well with our present calculations using two semi-phenomenological theoretical approaches. One employs the independent-atom model with the screening-corrected additivity rule (IAM-SCAR), while the other uses the continuum-multiple-scattering method in conjunction with a parameter-free exchange-polarization approximation. Since OCS is a polar molecule, further dipole-induced rotational excitation cross sections have been calculated in the framework of the first Born approximation and incoherently added to the IAM-SCAR results. In comparison with the calculated DCS for the S atom, atomic-like behavior for the angular distributions in both the OCS and CS₂ scattering systems is observed. Integrated elastic cross sections are obtained by extrapolating the experimental measurements, with the aid of the theoretical calculations, for those scattering angles below 10° and above 150°. These values are then compared with the available total cross sections.The present work has been supported by the Japanese Ministry of Education, Sport, Culture and Technology and the Australian Research Council through its Centers of Excellence program. PL-V acknowledges his Visiting Professor position at Sophia University, Tokyo, Japan and also the Portuguese PEst-OE/FIS/UI0068/2011 grant. This work forms part of the EU/ESF COST Action CM0805 programme “The Chemical Cosmos.” M.J.B. and S.J.B. acknowledge the JSPS for provision of a Senior Fellowship, and the University of Malaya for their hospitality as Visiting Professor F. Blanco and Professor G. García acknowledge partial financial support of the Spanish Ministerio de Economia y Competitividad through Project No. FIS2009-10245 as well as the EU/ESF COST Action MP1002