How the free limbs are used by elite high jumpers in generating vertical velocity

The aim of this study was to quantify how elite high jumpers used their free limbs in a competitive high jump and to estimate the contribution that these made to vertical take-off velocity. This was achieved by analysing the competitive performances of six elite male high jumpers using 3D motion analysis and assessing limb function using the relative momentum method. The mean peak relative momentum of the arm nearest to the bar at take-off was 9.4 kg m s(-1), while that of the arm furthest away from the bar was 11.3 kg m s(-1) and these did not differ significantly. The free (lead) leg reached a mean peak relative momentum of 20.9 kg m s(-1). At touch-down the free leg had a large positive relative momentum that was offset by the negative relative momentum of the arms, although their combined value still remained positive. The mean combined free limbs' relative momentum at touch-down was 13.8 kg m s(-1) and reached a peak of 37.6 kg m s(-1). The difference between these two values amounted to 7.1 % of whole-body momentum, which was judged to be the amount by which the free limbs contributed to performance. The arms had a greater influence on performance than had the lead leg. This was because the lead leg increased its relative momentum little during the contact period while the arms had an initial negative value that increased markedly after touch-down. The compressive force exerted by the motion of the free limbs, estimated by the change in the combined free limbs' relative momentum, reached a mean peak of 366 N and was greatest at 37% of the contact period. It was concluded that to maximize the contribution the free limbs can make to performance, given the restraints imposed on technique by other performance requirements, the arms should have a vigorous downward motion at touch-down to make the most use of the high (but little changing) relative momentum of the lead leg.     

Specific serodiagnosis of human leishmaniasis with recombinant Leishmania P2 acidic ribosomal proteins

The Leishmania P2 proteins have been analyzed as potential tools for the immunodiagnosis of human mucocutaneous and visceral leishmaniasis. Two recombinant Leishmania infantum proteins, rLIP2a and rLip2b, were used. The analysis indicated that the rLiP2a and rLiP2b proteins are recognized by 76% (16 of 21) and 42% (9 of 21), respectively, of sera from patients with mucocutaneous leishmaniasis and by 50% (5 of 10) and 40% (4 of 10), respectively, of sera from patients with visceral leishmaniasis. The Leishmania P2 proteins were engineered to have deletions of particular amino acids from the carboxyl-terminal region in order to avoid cross-reactivity with sera from patients with systemic lupus erythematosus and Chagas' disease, since it is known that this region is the main target of the autoantibodies present in sera from these patients. The results show that while the modified recombinant proteins rLiP2a-Q and rLiP2b-Q, in which the five carboxyl-terminal amino acids had been deleted, maintain the leishmaniasis-specific epitopes, they do not react with sera from patients with autoimmune disease and Chagas' disease. For this reason, and also because the sera from patients with tuberculosis and leprosy, diseases that have to be considered in a differential clinical diagnosis of infectious diseases, do not react with the rLiP2a-Q or rLiP2b-Q protein, we think that the engineered proteins may be considered specific tools for the immunodiagnosis of mucocutaneous and visceral leishmaniasis.     

A new method to compare planned and achieved position of an orthopaedic implant

The present study describes an automatic method to evaluate the efficacy of a computer aided orthopaedic surgery system by comparing the position of the joint implant, as derived from post-operative computed tomography (CT) scans, to that planned by the surgeon before the operation. The method relies on two spatial registrations, one to align the post-operative femur with the pre-operative femur, the second to compute the planned versus achieved (PVA) accuracy as the roto-translation that registers the pre-operative implant position with the post-operative position. Two surface registration algorithms (a generic average distance minimisation and the specialised iterative closest point (ICP) method) were comparatively evaluated first on a set of test cases to measure the absolute accuracy and robustness with respect to peculiar situations such as a distant starting point. The average distance method failed the registration of one test case and showed peak errors of 0.97 degrees on the rotations and 3.09 mm on the translations. The ICP method was found much more efficient and was able to register all test cases. The peak error was 0.44 degrees on the rotations and 0.67 mm on the translations. The ICP method was then used to compute the PVA accuracy on six clinical cases treated with a CT-based planning system in combination with conventional surgical procedures. The method successfully processed all cases demonstrating the efficacy of the proposed procedure in the specific application.     

Endothelial cell-matrix interactions

Dynamic interactions between endothelial cells and components of their surrounding extracellular matrix are necessary for the invasion, migration, and survival of endothelial cells during angiogenesis. These interactions are mediated by matrix receptors that initiate intracellular signaling cascades in response to binding to specific extracellular matrix molecules. The interactions between endothelial cells and their environment are also modulated by enzymes that degrade different matrix components and thus enable endothelial invasion. Recent reports on gene targeting in mice have confirmed the role of two classes of matrix receptors, integrins and cell surface heparan sulfate proteoglycans, and a group of matrix degrading proteolytic enzymes, matrix metalloproteinases, in angiogenesis. The significance of endothelial cell-matrix interactions is further supported by several ongoing clinical trials that analyze the effects of drugs blocking this interaction on angiogenesis-dependent growth of human tumors.     

Density-driven flow and solute transport problems. A 2-D numerical model based on the network simulation method

The network simulation method, based on the formal equivalence between physical systems and electrical networks, solves numerical problems of relatively mathematical complexity in a versatile, efficient and computationally fast way. In this paper, the method is applied for the first time to the design of a general purpose model for simulating two-dimensional transient density-driven flow and solute transport through porous media, a mathematical model made up by coupled, nonlinear differential equations. Using the Boussinesq approximation and the stream function formulation, the model is used to solve two typical problems related with groundwater flows. Isochlor concentration and stream function curves are presented and successfully compared with those of other authors. Simulation is carried out using the digital computer program Pspice with relatively low computing times.     

Synthesis and Theoretical Study of New Guanylated Cyclophosphazenes and Their Use in the CO2 Fixation into Styrene Carbonate

Three new guanylated cyclophosphazenes G1–G3 have been synthesized through the catalytic guanylation of three different bi, tetra and hexa (p-aminophenoxy)-cyclophosphazenes by using N,N’-diisopropylcarbodiimide as guanylating agent, ZnEt₂ as catalyst and dry tetrahydrofuran as solvent. The resulting products have been characterized by ¹H, ¹³C{¹H} and ³¹P{¹H} NMR spectroscopy. The hexaguanylated cyclophosphazenes exhibit a deep purple colour, unusual for this type of compounds. The electronic structure of these compounds was investigated by carrying out density functional calculations at PBE-D3(BJ)/TZP level of theory. The molecular structural analysis reveals that aromatic rings are stacked and time dependent density functional calculations show that a charge transfer electronic transition occurs between the aromatic rings which absorb light around 500–700 nm. Finally, the catalytic usefulness of guanylated cyclophosphazene compounds G1–G3 has been proven by the preparation of styrene carbonate from the reaction between styrene oxide and carbon dioxide.