Incidence and Prevention of Injury of the Anterior Cruciate Ligament in Females

According to the American College of Sports Medicine, women are two to eight times more likely to sustain an anterior cruciate ligament injury than men at the same level of performance. This high incidence of women with an ACL injury is thought to be due to a number of gender differences. This study examines the research that has been conducted to determine the reason for the disproportionate incidence of anterior cruciate ligament in female population. The study encompasses anatomical structure of the knee joint, structural differences in the male and female knee, hormonal influences, biomechanical influences, neuromuscular influences, and strategies for prevention. If intrinsic and extrinsic risk factors for women can be determined and altered, then steps can be taken to reduce the risk of an anterior cruciate ligament injury in women

The Causal Cascade to Multiple Sclerosis: A Model for MS Pathogenesis

BACKGROUND: MS pathogenesis seems to involve both genetic susceptibility and environmental risk factors. Three sequential factors are implicated in the environmental risk. The first acts near birth, the second acts during childhood, and the third acts long thereafter. Two candidate factors (vitamin D deficiency and Epstein-Barr viral infection) seem well suited to the first two environmental events. METHODOLOGY/PRINCIPAL FINDINGS: A mathematical Model for MS pathogenesis is developed, incorporating these environmental and genetic factors into a causal scheme that can explain some of the recent changes in MS-epidemiology (e.g., increasing disease prevalence, a changing sex-ratio, and regional variations in monozygotic twin concordance rates). CONCLUSIONS/SIGNIFICANCE: This Model suggests that genetic susceptibility is overwhelmingly the most important determinant of MS pathogenesis. Indeed, over 99% of individuals seem genetically incapable of developing MS, regardless of what environmental exposures they experience. Nevertheless, the contribution of specific genes to MS-susceptibility seems only modest. Thus, despite HLA DRB1*1501 being the most consistently identified genetic marker of MS-susceptibility (being present in over 50% of northern MS patient populations), only about 1% of individuals with this allele are even genetically susceptible to getting MS. Moreover, because genetic susceptibility seems so similar throughout North America and Europe, environmental differences principally determine the regional variations in disease characteristics. Additionally, despite 75% of MS-patients being women, men are 60% more likely to be genetically-susceptible than women. Also, men develop MS at lower levels of environmental exposure than women. Nevertheless, women are more responsive to the recent changes in environmental-exposure (whatever these have been). This explains both the changing sex-ratio and the increasing disease prevalence (which has increased by a minimum of 32% in Canada over the past 35 years). As noted, environmental risk seems to result from three sequential components of environmental exposure. The potential importance of this Model for MS pathogenesis is that, if correct, a therapeutic strategy, designed to interrupt one or more of these sequential factors, has the potential to markedly reduce or eliminate disease prevalence in the future

Temperature Control of Fimbriation Circuit Switch in Uropathogenic Escherichia coli: Quantitative Analysis via Automated Model Abstraction

Uropathogenic Escherichia coli (UPEC) represent the predominant cause of urinary tract infections (UTIs). A key UPEC molecular virulence mechanism is type 1 fimbriae, whose expression is controlled by the orientation of an invertible chromosomal DNA element—the fim switch. Temperature has been shown to act as a major regulator of fim switching behavior and is overall an important indicator as well as functional feature of many urologic diseases, including UPEC host-pathogen interaction dynamics. Given this panoptic physiological role of temperature during UTI progression and notable empirical challenges to its direct in vivo studies, in silico modeling of corresponding biochemical and biophysical mechanisms essential to UPEC pathogenicity may significantly aid our understanding of the underlying disease processes. However, rigorous computational analysis of biological systems, such as fim switch temperature control circuit, has hereto presented a notoriously demanding problem due to both the substantial complexity of the gene regulatory networks involved as well as their often characteristically discrete and stochastic dynamics. To address these issues, we have developed an approach that enables automated multiscale abstraction of biological system descriptions based on reaction kinetics. Implemented as a computational tool, this method has allowed us to efficiently analyze the modular organization and behavior of the E. coli fimbriation switch circuit at different temperature settings, thus facilitating new insights into this mode of UPEC molecular virulence regulation. In particular, our results suggest that, with respect to its role in shutting down fimbriae expression, the primary function of FimB recombinase may be to effect a controlled down-regulation (rather than increase) of the ON-to-OFF fim switching rate via temperature-dependent suppression of competing dynamics mediated by recombinase FimE. Our computational analysis further implies that this down-regulation mechanism could be particularly significant inside the host environment, thus potentially contributing further understanding toward the development of novel therapeutic approaches to UPEC-caused UTIs

Spectral hole burning: examples from photosynthesis

The optical spectra of photosynthetic pigment–protein complexes usually show broad absorption bands, often consisting of a number of overlapping, ‘hidden’ bands belonging to different species. Spectral hole burning is an ideal technique to unravel the optical and dynamic properties of such hidden species. Here, the principles of spectral hole burning (HB) and the experimental set-up used in its continuous wave (CW) and time-resolved versions are described. Examples from photosynthesis studied with hole burning, obtained in our laboratory, are then presented. These examples have been classified into three groups according to the parameters that were measured: (1) hole widths as a function of temperature, (2) hole widths as a function of delay time and (3) hole depths as a function of wavelength. Two examples from light-harvesting (LH) 2 complexes of purple bacteria are given within the first group: (a) the determination of energy-transfer times from the chromophores in the B800 ring to the B850 ring, and (b) optical dephasing in the B850 absorption band. One example from photosystem II (PSII) sub-core complexes of higher plants is given within the second group: it shows that the size of the complex determines the amount of spectral diffusion measured. Within the third group, two examples from (green) plants and purple bacteria have been chosen for: (a) the identification of ‘traps’ for energy transfer in PSII sub-core complexes of green plants, and (b) the uncovering of the lowest k = 0 exciton-state distribution within the B850 band of LH2 complexes of purple bacteria. The results prove the potential of spectral hole burning measurements for getting quantitative insight into dynamic processes in photosynthetic systems at low temperature, in particular, when individual bands are hidden within broad absorption bands. Because of its high-resolution wavelength selectivity, HB is a technique that is complementary to ultrafast pump–probe methods. In this review, we have provided an extensive bibliography for the benefit of scientists who plan to make use of this valuable technique in their future research

SrMn3O6: an incommensurate modulated tunnel structure

The crystallographic structure of a mixed valent manganite SrMn3O6 with a 1D modulated structure is reported. The SrMn3O6 structure can be described with the basic subcell space group Pnma (a=9.1334(5) Å; b=2.8219(2) Å; c=12.0959(7)Å), but transmission electron microscopy revealed that the study of the real structure requires a 4D-formalism approach with superspace group P21/a(αβ0)00 (unique axis c), with a modulation wave vector q having the approximate components (0.52a*+0.31b*). The crystallographic structure is closely related to those of NaxFexTi2−xO4 and Pb1.5BaMn6Al2O16, comprising of unusual “figure-of-eight”-shaped tunnels, made up of strings of edge- and corner-sharing (Fe/Ti)O6 or (Mn/Al)O6 octahedra, with the other cations situated in the tunnel cavities. Structural refinement was performed on X-ray and neutron powder diffraction data using the 4D formalism. All atoms in the crystal are affected by a displacive modulation wave, and a saw tooth function is employed to model the displacement and occupancy of the Sr sites. Magnetic susceptibility measurements reveal a sharp antiferromagnetic transition with TN46 K

Attention and Intention Goals Can Mediate Disruption in Human-Computer Interaction

Part 1: Long and Short PapersInternational audienceMultitasking environments cause people to be interrupted constantly, often interfering with their ongoing tasks, activities and goals. This paper focuses on the disruption caused by interruptions and presents a disruption mediating approach for balancing the negative effects of interruptions with respect to the benefits of interruptions relevant to the user goals. Our work shows how Disruption Manager utilizing context and relationships to user goals and tasks can assess when and how to present interruptions in order to reduce their disruptiveness.The Disruption Management Framework was created to take into consideration motivations that influence people’s interruption decision process. The framework predicts the effects from interruptions using a three-layer software architecture: a knowledge layer including information about topics related to the ongoing activity, an intermediate layer including summarized information about the user tasks and their stages, and a low level layer including implicit low granularity information, such as mouse movement, context switching and windowing activity to support fail-safe disruption management when no other contextual information is available. The manager supports implicit monitoring of ongoing behaviors and categorizing possible disruptive outcome given the user and system state. The manager monitors actions and uses common sense reasoning in its model to compare communication stream topics with topics files that are active on the desktop.Experiments demonstrate that disruption manager significantly reduces the impact of interruptions and improve people’s performance in a multi-application desktop scenario with email and instant messaging. In a complex order taking activity, disruption manager yielded a 26% performance increase for tasks prioritized as being important and a 32.5% increase for urgent tasks. The evaluation shows that the modulated interruptions did not distract or troubled users. Further, subjects using the Disruption Manager were 5 times more likely to respond effectively to instant messages