Association between spondylolisthesis and L5 fracture in patients with osteogenesis imperfecta

To investigate if an association between spondylolisthesis and L5 fracture occurs in patients affected by Osteogenesis Imperfecta (O.I.). Methods Anteroposterior and lateral radiograms were performed on the sample (38 O.I. patients, of whom 19 presenting listhesis); on imaging studies spondylolisthesis was quantified according to the Meyerding classification. Genant’s semiquantitative classification was applied on lateral view to evaluate the L5 fractures; skeleton spinal morphometry (MXA) was carried out on the same images to collect quantitative data comparable and superimposable to Genant’s classification. The gathered information were analyzed through statistical tests (O.R., χ 2 test, Fisher’s test, Pearson’s correlation coefficient). Results The prevalence of L5 fractures is 73.7 % in O.I. patients with spondylolisthesis and their risk of experiencing such a fracture is twice than O.I. patients without listhesis (OR 2.04). Pearson’s χ 2 test demonstrates an association between L5 spondylolisthesis and L5 fracture, especially with moderate, posterior fractures (p = 0.017) and primarily in patients affected by type IV O.I. Conclusions Spondylolisthesis represents a risk factor for the development of more severe and biconcave/posterior type fractures of L5 in patients suffering from O.I., especially in type IV. This fits the hypothesis that the anterior sliding of the soma of L5 alters the dynamics of action of the load forces, localizing them on the central and posterior heights that become the focus of the stress due to movement of flexion–extension and twisting of the spine. As a result, there is greater probability of developing an important subsidence of the central and posterior walls of the soma

Stability properties of an inverse parabolic problem with unknown boundaries

We treat the stability issue for an inverse problem arising from nondestructive evaluation by thermal imaging. We consider the determination of an unknown portion of the boundary of a thermic conducting body by overdetermined boundary data for a parabolic initial-boundary value problem.We obtain that when the unknown part of the boundary is a priori known to be smooth, the data are as regular as possible and all possible measurements are taken into account, the problem is exponentially ill-posed. Then, we prove that a single measurement with some a priori information on the unknown part of the boundary and minimal assumptions on the data, in particular on the thermal conductivity, is enough to have stable determination of the unknown boundary. Given the exponential illposedness, the stability estimate obtained is optimal

A Strategy for Passive Control of Natural Roll-Waves in Power-Law Fluids through Inlet Boundary Conditions

n/

Applicability of Kinematic and Diffusive models for mud-flows: a steady state analysis

The paper investigates the applicability of Kinematic and Diffusive Wave models for mud-flows with a power-law shear-thinning rheology. In analogy with a well-known approach for turbulent clear-water flows, the study compares the steady flow depth profiles predicted by approximated models with those of the Full Dynamic Wave one. For all the models and assuming an infinitely wide channel, the analytical solution of the flow depth profiles, in terms of hypergeometric functions, is derived. The accuracy of the approximated models is assessed by computing the average, along the channel length, of the errors, for several values of the Froude and kinematic wave numbers. Assuming the threshold value of the error equal to 5%, the applicability conditions of the two approximations have been individuated for several values of the power-law exponent, showing a crucial role of the rheology. The comparison with the clear-water results indicates that applicability criteria for clear-water flows do not apply to shearthinning fluids, potentially leading to an incorrect use of approximated models if the rheology is not properly accounted for

Isolated olecranon fractures in children affected by osteogenesis imperfecta type I treated with single screw or tension band wiring system: outcomes and pitfalls in relation to bone mineral density

The purpose of this study is to compare the results of 2 techniques, tension band wiring (TBW) and fixation with screws, in olecranon fractures in children affected with osteogenesis imperfecta (OI) type I. Between 2010 and 2014, 21 olecranon fractures in 18 children with OI (average age: 12 years old) were treated surgically. Ten patients were treated with the screw fixation and 11 with TBW. A total of 65% of olecranon fractures occurred as a result of a spontaneous avulsion of the olecranon during the contraction of the triceps muscle. The average follow-up was 36 months. Among the children treated with 1 screw, 5 patients needed a surgical revision with TBW due to a mobilization of the screw. In this group, the satisfactory results were 50%. In patients treated with TBW, the satisfactory results were 100% of the cases. The average Z-score, the last one recorded in the patients before the trauma, was -2.53 in patients treated with screw fixation and -2.04 in those treated with TBW. TBW represents the safest surgical treatment for patients suffering from OI type I, as it helps to prevent the rigidity of the elbow through an earlier recovery of the range of motion, and there was no loosening of the implant. In analyzing the average Z-score before any fracture, the fixation with screws has an increased risk of failure in combination with low bone mineral density

Relatório do cruzeiro realizado no Banco de Sofala pelo navio "Pantikapey" de 7/23 - Junho de 1981: camarāo de superficíe

This report of the cruise along the Sofala Bank (Mozambique) describes the catch composition and catch distributions of the shallow water shrimp. Biological data are given for Penaeus indicus and Metapenaeus monoceros which represent 77% of the total catch

Impact dynamics of mud flows against rigid walls

Mud flows represent one of the major causes of natural hazards in mountain regions. Similarly to debris flows, they consist of a hyper-concentrated mixture of water and sediments flowing down a slope and may cause serious damages to people and structures. The present paper investigates the force produced by a dam-break wave of mud impacting against a rigid wall. A power-law shearthinning model is used to describe the rheology of the hyper-concentrated mixture. A onedimensional shallow water model is adopted and a second-order Finite Volume scheme is employed to numerically solve the governing equations. The results indicate that depending on the fluid rheological parameters and on the bottom slope, there exists a minimum value of the wall distance above which the peak force does not exceed the asymptotic value of the hydrostatic final condition. For two different values of the channel slope, the dimensionless value of this lower bound is individuated for several values of the power-law exponent and of a dimensionless Basal Drag coefficient. An estimation of the maximum peak force for wall distance smaller than the minimum value is also provided