Smart Biomechanical Adaptation Revealed by the Structure of Ostrich Limb Bones.

Ostriches are known to be the fastest bipedal animal alive; to accomplish such an achievement, their anatomy evolved to sustain the stresses imposed by running at such velocities. Ostriches represent an excellent case study due to the fact that their locomotor kinematics have been extensively studied for their running capabilities. The shape and structure of ostrich bones are also known to be optimized to sustain the stresses imposed by the body mass and accelerations to which the bones are subjected during movements. This study focuses on the limb bones, investigating the structure of the bones as well as the material properties, and how both the structure and material evolved to maximise the performance while minimising the stresses applied to the bones themselves. The femoral shaft is hollowed and it presents an imbricate structure of fused bone ridges connected to the walls of the marrow cavity, while the tibial shaft is subdivided into regions having different mechanical characteristics. These adaptations indicate the optimization of both the structure and the material to bear the stresses. The regionalization of the material highlighted by the mechanical tests represents the capability of the bone to adapt to external stimuli during the life of an individual, optimizing not only the structure of the bone but the material itself.

Multibody analysis and soft tissue strength refute supersonic dinosaur tail.

Sauropod dinosaurs are well known for their massive sizes and long necks and tails. Among sauropods, flagellicaudatan dinosaurs are characterized by extreme tail elongation, which has led to hypotheses regarding tail function, often compared to a whip. Here, we analyse the dynamics of motion of a 3D model of an apatosaurine flagellicaudatan tail using multibody simulation and quantify the stress-bearing capabilities of the associated soft tissues. Such an elongated and slender structure would allow achieving tip velocities in the order of 30 m/s, or 100 km/h, far slower than the speed of sound, due to the combined effect of friction of the musculature and articulations, as well as aerodynamic drag. The material properties of the skin, tendons, and ligaments also support such evidence, proving that in life, the tail would not have withstood the stresses imposed by travelling at the speed of sound, irrespective of the conjectural 'popper', a hypothetical soft tissue structure analogue to the terminal portion of a bullwhip able to surpass the speed of sound.

Compression Behavior of EBM Printed Auxetic Chiral Structures.

In this study, the cyclic compression and crush behavior of chiral auxetic lattice structures produced from titanium alloy (Ti6Al4V) metallic powder using electron beam melting (EBM) additive manufacturing technology is investigated numerically and experimentally. For material characterization and understanding the material behavior of EBM printed parts, tensile and three-point flexural tests were conducted. Log signals produced during the EBM process were investigated to confirm the stability of process and the health of the produced parts. Furthermore, a compressive cyclic load profile was applied to the EBM printed chiral units having two different thicknesses to track their Poisson's ratios and displacement limits under large displacements in the absence of degradation, permanent deformations and failures. Chiral units were also crushed to investigate the effect of failure and deformation mechanisms on the energy absorption characteristics. Moreover, a surface roughness study was conducted due to high surface roughness of EBM printed parts, and an equation is offered to define load-carrying effective areas to prevent misleading cross-section measurements. In compliance with the equation and tensile test results, a constitutive equation was formed and used after a selection and calibration process to verify the numerical model for optimum topology design and mechanical performance forecasting using a non-linear computational model with failure analysis. As a result, the cyclic compression and crush numerical analyses of EBM printed Ti6Al4V chiral cells were validated with the experimental results. It was shown that the constitutive equation of EBM printed as-built parts was extracted accurately considering the build orientation and surface roughness profile. Besides, the cyclic compressive and crush behavior of chiral units were investigated. The regions of the chiral units prone to prematurely fail under crush loads were determined, and deformation modes were investigated to increase the energy absorption abilities.

Prompt and unavoidable requalification of ordinary hospital wards into a centralized department characterized by high-intensity treatment due to COVID-19 epidemic: the experience of Romano di Lombardia Hospital.

The Coronavirus epidemic quickly spread in Italy from China. In particular, it affected Bergamo province where Romano di Lombardia hospital is situated. Therefore, this hospital felt the urgency to requalify its activity in no time. It transformed itself into a unique centralized subintensive department to treat COVID-19 patients. The factors that made it possible to adequately face the stress due to patients' hospitalization were human resources and innovative elements to provide oxygen therapy. It is to underline that the logistic and methodological reality was not planned to cope with this emergency.

Mesenteric Artery Thrombosis, Microvascular Intestinal Endothelitiis, and Guillain-Barrè Syndrome in the Same SARS-CoV-2 Patient.

Coronavirus disease 2019 (COVID-19) in humans is a novel disease that can affect every organ of the body, with life-threatening consequences. Microvascular lesions and thrombosis have been previously reported in the lung, kidney, and brain. We report a case of combined intestinal lesions and Guillain-Barrè Syndrome in a patient suffering from COVID-19 in the absence of clear laboratory predictors of upcoming complications. The patient survived the severe respiratory syndrome but died after virus-related systemic organ failure.

The Borel map in locally integrable structures.

Given a locally integrable structure V over a smooth manifold Ω and given p ∈ Ω we define the Borel map of V at p as the map which assigns to the germ of a smooth solution of V at p its formal Taylor power series at p. In this work we continue the study initiated in Barostichi et al. (Math. Nachr. 286(14-15):1439-1451, 2013), Della Sala and Lamel (Int J Math 24(11):1350091, 2013) and present new results regarding the Borel map. We prove a general necessary condition for the surjectivity of the Borel map to hold and also, after developing some new devices, we study some classes of CR structures for which its surjectivity is valid. In the final sections we show how the Borel map can be applied to the study of the algebra of germs of solutions of V at p.

Enhanced characterization of solid solitary pulmonary nodules with Bayesian analysis-based computer-aided diagnosis.

The aim of this study was to prospectively assess the accuracy gain of Bayesian analysis-based computer-aided diagnosis (CAD) vs human judgment alone in characterizing solitary pulmonary nodules (SPNs) at computed tomography (CT). The study included 100 randomly selected SPNs with a definitive diagnosis. Nodule features at first and follow-up CT scans as well as clinical data were evaluated individually on a 1 to 5 points risk chart by 7 radiologists, firstly blinded then aware of Bayesian Inference Malignancy Calculator (BIMC) model predictions. Raters' predictions were evaluated by means of receiver operating characteristic (ROC) curve analysis and decision analysis. Overall ROC area under the curve was 0.758 before and 0.803 after the disclosure of CAD predictions (P = 0.003). A net gain in diagnostic accuracy was found in 6 out of 7 readers. Mean risk class of benign nodules dropped from 2.48 to 2.29, while mean risk class of malignancies rose from 3.66 to 3.92. Awareness of CAD predictions also determined a significant drop on mean indeterminate SPNs (15 vs 23.86 SPNs) and raised the mean number of correct and confident diagnoses (mean 39.57 vs 25.71 SPNs). This study provides evidence supporting the integration of the Bayesian analysis-based BIMC model in SPN characterization.

Pedicle screw cement augmentation. A mechanical pullout study on different cement augmentation techniques.

Pedicle screws with polymethyl methacrylate (PMMA) cement augmentation have been shown to significantly improve the fixation strength in a severely osteoporotic spine. However, the efficacy of screw fixation for different cement augmentation techniques remains unknown. This study aimed to determine the difference in pullout strength between different cement augmentation techniques. Uniform synthetic bones simulating severe osteoporosis were used to provide a platform for each augmentation technique. In all cases a polyaxial screw and acrylic cement (PMMA) at medium viscosity were used. Five groups were analyzed: I) only screw without PMMA (control group); II) retrograde cement pre-filling of the tapped area; III) cannulated and fenestrate screw with cement injection through perforation; IV) injection using a standard trocar of PMMA (vertebroplasty) and retrograde pre-filling of the tapped area; V) injection through a fenestrated trocar and retrograde pre-filling of the tapped area. Standard X-rays were taken in order to visualize cement distribution in each group. Pedicle screws at full insertion were then tested for axial pullout failure using a mechanical testing machine. A total of 30 screws were tested. The results of pullout analysis revealed better results of all groups with respect to the control group. In particular the statistical analysis showed a difference of Group V (p = 0.001) with respect to all other groups. These results confirm that the cement augmentation grants better results in pullout axial forces. Moreover they suggest better load resistance to axial forces when the distribution of the PMMA is along all the screw combining fenestration and pre-filling augmentation technique.

Development and experimental validation of a numerical tool for structural health and usage monitoring systems based on chirped grating sensors.

The interest of the aerospace industries in structural health and usage monitoring systems is continuously increasing. Among the techniques available in literature those based on Fibre Bragg Grating sensors are much promising thanks to their peculiarities. Different Chirped Bragg Grating sensor configurations have been investigated in this paper. Starting from a numerical model capable of simulating the spectral response of a grating subjected to a generic strain profile (direct problem), a new code has been developed, allowing strain reconstruction from the experimental validation of the program, carried out through different loading cases applied on a chirped grating. The wavelength of the reflection spectrum for a chirped FBG has a one-to-one correspondence to the position along the gauge section, thus allowing strain reconstruction over the entire sensor length. Tests conducted on chirped FBGs also evidenced their potential for SHM applications, if coupled with appropriate numerical strain reconstructions tools. Finally, a new class of sensors-Draw Tower Grating arrays-has been studied. These sensors are applicable to distributed sensing and load reconstruction over large structures, thanks to their greater length. Three configurations have been evaluated, having different spatial and spectral characteristics, in order to explore possible applications of such sensors to SHM systems.

Bergman spaces of natural G-manifolds.

Let G be a unimodular Lie group, X a compact manifold with boundary, and M the total space of a principal bundle [Formula: see text] so that M is also a strongly pseudoconvex complex manifold. In this work, we show that if there exists a point [Formula: see text] such that [Formula: see text] is contained in the complex tangent space [Formula: see text] of bM at p, then the Bergman space of M is large. Natural examples include the gauged G-complexifications of Heinzner, Huckleberry, and Kutzschebauch.

Normal anatomy and variants of the venous cardiac system in MDCT coronary angiography.

Three separate venous systems drain the blood returning from the heart walls. These veins are characterised by remarkable variability in terms of frequency, size and course. The knowledge of cardiac venous anatomy is of primary importance during interventional cardiac procedures that require catheterisation of cardiac veins. Some anatomical variants may hinder or contraindicate access to target veins. Coronary angiography (CA) with multidetector computed tomography (MDCT-CA) and multiplanar reformations (MPR), maximum intensity projection (MIP) and 3D reconstructions provides noninvasive visualisation of normal cardiac veins and anatomical variants. The purpose of this pictorial review is to describe by MDCT-CA the anatomy and main variants of the cardiac venous system.

Learning curve in multidetector CT coronary angiography (MDCT-CA).

PURPOSE: Coronary angiography using multidetector computed tomography (MDCT-CA) is a recent technique for the nonivasive study of coronary arteries. This study assessed the diagnostic accuracy of coronary artery stenosis evaluation obtained by three readers at different levels of training or at different points of the learning curve proposed by the international guidelines. MATERIALS AND METHODS: Three radiologists in training with different levels of experience in MDCT-CA scored 50 cases at various time points of the learning curve: baseline, 4 weeks, 8 weeks and 6 months. The trainee radiologists evaluated the degree of stenosis on each coronary segment, and overall accuracy was calculated on a per-segment, pervessel and per-patient basis. RESULTS: All readers improved analysis accuracy per segment (range, 73-90%); sensitivity reached 45% per segment, 84% per vessel and 93% per patient; specificity was 99% per segment and vessel and 98% per patient. Positive and negative predictive values increased to 94% and 92%, respectively. CONCLUSIONS: Although all readers improved in diagnostic performance with growing experience with MDCT-CA, a longer training period may be necessary to achieve adequate levels of expertise in MDCT-CA to be able to perform as independent readers.

Non invasive cardiac vein mapping: role of multislice CT coronary angiography.

PURPOSE: Coronary venous anatomy is of primary importance when implanting a cardiac resynchronization therapy device, besides, the coronary sinus can be differently enlarged depending on chronic heart failure. The aim of this study is to evaluate the usefulness of Coronary CTA in describing the coronary venous tree and in particular the coronary sinus and detecting main venous system variants. MATERIALS AND METHODS: 301 consecutive patients (196 ♂, mean age 63.74 years) studied for coronary artery disease with 64 slice Coronary CTA were retrospectively examined. The acquisition protocol was the standard acquisition one used for coronary artery evaluation but the cardiac venous system were visualized. The cardiac venous system was depicted using 3D, MPR, cMPR and MIP post-processing reconstructions on an off-line workstation. For each patient image quality, presence and caliber of the coronary sinus (CS), great cardiac vein (GCV), middle vein (MV), anterior interventricular vein (AIV), lateral cardiac vein (LCV), posterior cardiac vein (PCV), small cardiac vein (SCV) and presence of variant of the normal anatomy were examined and recorded. RESULTS: CS, GCV, MV and AIV were visualized in 100% of the cases. The LCV was visualized in 255/301 (84%) patients, the PCV in 248/301 (83%) patients and the SCV in 69/301 (23%) patients. Mean diameter of the CS was 8.7 mm in 276/301 (91.7%) patients without chronic heart failure and 9.93 mm in 25/301 (8.3%) patients with chronic heart failure. CONCLUSIONS: Coronary CTA allows non invasive mapping of the cardiac venous system and may represent a useful presurgical tool for biventricular pacemaker devices implantation.

Posterior spinal instrumentation: biomechanical study on the role of rods on hardware response to axial load.

Posterior spinal instrumentation is frequently used for the treatment of spine disorders. Importantly, different requirements have to be considered for the optimal use of these systems in various clinical scenarios. In this work, we focused on the role of rods diameter on hardware's stiffness. For this purpose, we established an in vitro model and compared the response to axial load of a posterior stabilization system, characterized by rods of different diameter (4, 5, 6 mm), with that of Dynesys®. Intuitively, the higher the stiffness of the hardware, the lower the load is transferred to the disc. However, the 4 hardware tested showed a different trend in the response to the load regimens: when increasing the load, more flexible systems display a progressive reduction in the percentage of load which is transferred to the disc while more rigid system display the opposite trend. Considering that the load which is transferred, and not by-passed by the hardware, influences the healing of a fracture; the integration of a bone graft or a cage; the fusion process, these data have a relevant impact on clinical practice and highlight features that have to be considered in the choice for the optimal posterior spinal instrumentation.

The third component of the complement (C3) is a marker of the risk of atherogenesis.

AIM: The aim of this study was to assess the association between the third component of the complement (C3) and other risk factors of coronary heart disease. METHODS AND RESULTS: We evaluated 1200 individuals aged 25-74 years (600 men and 600 women). A strong relationship was shown between serum C3 and both body mass index (BMI, P<0.01) and fibrinogen (P<0.01). We found a significant, independent correlation with: platelet count (P<0.01), insulin level (P<0.01), triglycerides (P<0.01), low-density lipoprotein (LDL) cholesterol (P<0.01), and an inverse correlation with cigarette smoking (P<0.01). CONCLUSIONS: A high concentration of C3 is a marker of a profile at risk of atherogenesis.