Kinematic Approach for a Global-Local Coupling: Compressive Behaviour of a Delaminated Panel:

A kinematic approach to global/local coupling has been applied to investigate the behaviour of a delaminated stiffened composite panel, by using an in-house finite element based procedure. The delamination growth phenomenon has been simulated by employing fracture elements implemented in the B2000++® code, which are based on the Modified Virtual Crack Closure Technique (MVCCT); this technique is able to compute the energy release rate on the delamination front for each fracture mode. A very fine three-dimensional mesh in the delaminated region has been considered in order to obtain a good prediction of the delamination growth. The rest of the structure has been modelled by means of shell elements. A global/local approach based on point-wise multipoint constraint has been implemented in the in-house-code and used to connect shell meshes to solid ones. A numerical application on a delaminated composite stiffened panel taken from literature has been introduced. Models characterized by different levels of complexity, i.e. without delamination, with delamination, with delamination growth have been considered and compared to understand the effectiveness of the introduced kinematic approach

Numerical Investigation of the Failure Phenomena in Adhesively Bonded Joints by Means of a Multi-Linear Equivalent Plastic Stress/Strain Approach

Abstract In this work, a multi-linear material model for elastic-plastic response of ductile adhesives is proposed. Indeed, the proposed formulation allows to evaluate equivalent stress and strains to be used as material model input in FE commercial codes instead of the classical true stress and true strains. The presented model, which is capable to simulate the plasticity related phenomena and the failure event, has been implemented in the FEM code ABAQUS and used to numerically simulate the mechanical behaviour of adhesively bonded joints in traction. Several joints configurations have been considered with ductile, fragile and mix adhesives' behaviour to test the effectiveness and the range of applicability of the proposed model. Encouraging comparisons with literature experimental data demonstrates the added value of the suggested material model in predicting the failure of adhesively bonded joints

Banco de semillas en ambientes de las sierras de Azul (Buenos Aires, Argentina) con distinta intensidad de disturbios

A fin de evaluar el impacto de la agricultura sobre la flora potencial de pastizales serranos en el Partido de Azul (Buenos Aires, Argentina), se comparó el banco de semillas en los 20 cm superficiales del suelo entre dos sectores adyacentes en las primeras estribaciones serranas. Uno de ellos está sometido a agricultura permanente y el otro conserva un pastizal natural bajo pastoreo y quemas no programados.Este último sector presentó en promedio una densidad de 70.000 semm-2 contra 36.720 sem m-2 en el primero. La representación de semillas de especies nativas se redujo notablemente en el ambiente agrícola. Stipa caudata con 31360 sem m-2 resultó la especie más abundante en el pastizal. En el ambientede cultivo, su densidad se redujo a 9940 sem m-2 y fue superada por Chenopodium album con 10560 sem m-2. La similitud en la composición del banco fue de 55% en términos cualitativos y 27% en términos cuantitativos. Estos resultados evidencian que, en el área de estudio, el reemplazo del pastizal natural por agricultura reduce notoriamente las reservas de semillas y modifica la composición cualitativa y cuantitativa del banco con una elevada pérdida en la proporción de especies nativas

Investigation of the Effects of Autorotative Flare Index Variation on Helicopter Flight Dynamics in Autorotation

Autorotation is a flight condition whereby the engine of a helicopter is no longer supplying power to the main rotor system, which is driven solely by the upward flow of the air moving through the rotor. For helicopters, autorotation is a common emergency procedure performed by pilots to safely land the vehicle in the event of a power failure or tail-rotor failure. In the classic analysis of dynamic stability of helicopters in powered flight, it is common practice to neglect the effect of variation of rotor angular velocity, as the rotorspeed is constant. However, this assumption is no longer justified in case of autorotative flight. Therefore, the rotorspeed becomes an additional degree-of-freedom in autorotation, giving rise to a new stability mode that couples with classical rigid-body modes. The present paper aims at understanding the role of the rotorspeed degree-of-freedom in modifying the stability characteristics in autorotation of rotor systems with different autorotative flare indexes. Results show that the helicopter dynamics are considerably affected in autorotation as a consequence of the fact that the rotorspeed degree of freedom couples with the heave subsidence mode. Therefore, autorotation requires a different control strategy by the pilot and should not be mistakenly considered only as an energy management task. Furthermore, the autorotative flare index, used to characterize the autorotative performance during the preliminary design phase of a new helicopter, provides only energy information. Indeed, this paper demonstrates that high values of this index, representative of good autorotative performance in terms of available energy over required energy, may lead to degraded stability characteristics of the helicopter in autorotation.Control & Simulatio

Endometriosis and pregnancy. a single institution experience

Endometriosis may compromise the physiological course of pregnancy. The aim of this prospective observational study was to evaluate whether endometriosis causes a higher prevalence of obstetric and neonatal complications as well as a higher risk of caesarean section and to detect a possible correlation between the presence, type, and location of endometriosis and obstetric complications, previous surgery, and pregnancy outcome, as well as the influence of pregnancy on the course of the disease. We compared two cohorts of women with spontaneous pregnancy, with and without endometriosis. Obstetric and neonatal outcomes, mode of delivery, presence, type, and location of endometriotic lesions and the effect of pregnancy on the disease were analyzed. A total of 425 pregnancies were evaluated: 145 cases and 280 controls. Patients with endometriosis showed a higher incidence of miscarriage, threatened miscarriage, threatened preterm labor, preterm delivery, placental abruption, and a higher incidence of caesarean section. A significant correlation with pregnancy-induced hypertension and preeclampsia was found in the presence of adenomyosis. No difference in fetal outcome was found. One case of hemoperitoneum during pregnancy was observed. Pregnancy in women with endometriosis carries a higher risk of obstetric complications, such as miscarriage, threatened miscarriage, preterm labor, preterm birth, and a higher caesarean section rate. Endometriosis does not seem to influence fetal well-being

Secondary cytomegalovirus infections: How much do we still not know? Comparison of children with symptomatic congenital cytomegalovirus born to mothers with primary and secondary infection

congenital cytomegalovirus (cCMV) infection can follow primary and secondary maternal infection. growing evidence indicate that secondary maternal infections contribute to a much greater proportion of symptomatic cCMV than was previously thought. We performed a monocentric retrospective study of babies with cCMV evaluated from august 2004 to february 2021; we compared data of symptomatic children born to mothers with primary or secondary infection, both at birth and during follow up. among the 145 babies with available data about maternal infection, 53 were classified as having symptomatic cCMV and were included in the study: 40 babies were born to mothers with primary infection and 13 babies were born to mothers with secondary infection. Analyzing data at birth, we found no statistical differences in the rate of clinical findings in the two groups, except for unilateral sensorineural hearing loss (SNHL) which was significantly more frequent in patients born to mother with secondary infection than in those born to mother with primary infection (46.2 vs. 17.5%, P = 0.037). during follow up, we found a higher rate of many sequelae (tetraparesis, epilepsy, motor and speech delay, and unilateral SNHL) in the group of children born to mothers with secondary infection, with a statistical difference for tetraparesis and unilateral SNHL. otherwise, only children born to mothers with primary infection presented bilateral SNHL both at birth and follow up. Our data suggest that the risk of symptomatic cCMV and long-term sequelae is similar in children born to mother with primary and secondary CMV infection; it is important to pay appropriate attention to seropositive mothers in order to prevent reinfection and to detect and possibly treat infected babies

Huntingtin-mediated axonal transport requires arginine methylation by PRMT6

The huntingtin (HTT) protein transports various organelles, including vesicles containing neurotrophic factors, from embryonic development throughout life. To better understand how HTT mediates axonal transport and why this function is disrupted in Huntington's disease (HD), we study vesicle-associated HTT and find that it is dimethylated at a highly conserved arginine residue (R118) by the protein arginine methyltransferase 6 (PRMT6). Without R118 methylation, HTT associates less with vesicles, anterograde trafficking is diminished, and neuronal death ensues—very similar to what occurs in HD. Inhibiting PRMT6 in HD cells and neurons exacerbates mutant HTT (mHTT) toxicity and impairs axonal trafficking, whereas overexpressing PRMT6 restores axonal transport and neuronal viability, except in the presence of a methylation-defective variant of mHTT. In HD flies, overexpressing PRMT6 rescues axonal defects and eclosion. Arginine methylation thus regulates HTT-mediated vesicular transport along the axon, and increasing HTT methylation could be of therapeutic interest for HD

Impact of endometriosis on obstetric outcome after natural conception: a multicenter Italian study

Purpose To evaluate obstetric outcome in women with endometriosis who conceive naturally and receive standard obstetric care in Italy. Methods Cases were consecutive women with endometriosis managed in eleven Italian referral centers. Controls were women in whom endometriosis was excluded. All women filled in a questionnaire addressing previous natural pregnancies. Marginal logistic regression models were fitted to evaluate the impact of endometriosis on obstetric outcome. A post hoc analysis was performed within the endometriosis group comparing women with severe adenomyosis versus women with absent or mild adenomyosis. Results Three hundred and fifty-five pregnancies in endometriosis group and 741 pregnancies in control group were included. Women with endometriosis had a higher risk of preterm delivery < 34 weeks (6.4% vs 2.8%, OR 2.42, 95% CI 1.22–4.82), preterm delivery < 37 weeks (17.8% vs 9.7%, OR 1.98, 95% CI 1.23–3.19), and neonatal admission to Intensive Care Unit (14.1% vs 7.0%, OR 2.04, 95% CI 1.23–3.36). At post hoc analysis, women with endometriosis and severe adenomyosis had an increased risk of placenta previa (23.1% vs 1.8%, OR 16.68, 95% CI 3.49–79.71), cesarean delivery (84.6% vs 38.9%, OR 8.03, 95% CI 1.69–38.25) and preterm delivery < 34 weeks (23.1% vs 5.7%, OR 5.52, 95% CI 1.38–22.09). Conclusion Women with endometriosis who conceive naturally have increased risk of preterm delivery and neonatal admission to intensive care unit. When severe adenomyosis is coexistent with endometriosis, women may be at increased risk of placenta previa and cesarean delivery. Trial registration Clinical trial registration number: NCT03354793

Assessment of the Feasibility of an Extended Range Helicopter Operational Standard for Offshore Flights

The accident rate of rotorcraft has improved signi1cantly over the years but at a slow pace, and in any case the number of accident per 2ight hours is one or two order on magnitude higher than that of commercial aircraft. This could be reasonably related to the inherent higher risk associate with rotorcraft operations. This represent a strong evidence of the necessity to introduce airworthiness operation standards also in the rotorcraft community, as an effective mean to improve safety records, borrowing the experience done in the commercial air transport community with the introduction of ETOPS. In this paper a 1rst proposal of development of a safety standard for helicopter offshore operation is discussed together with the possible support to this development that could be given by the EU H2020 NITROS project

Impact of Orthologous Gene Replacement on the Circuitry Governing Pilus Gene Transcription in Streptococci

The evolutionary history of several genes of the bacterial pathogen Streptococcus pyogenes strongly suggests an origin in another species, acquired via replacement of the counterpart gene (ortholog) following a recombination event. An example of orthologous gene replacement is provided by the nra/rofA locus, which encodes a key regulator of pilus gene transcription. Of biological importance is the previous finding that the presence of the nra- and rofA-lineage alleles, which are approximately 35% divergent, correlates strongly with genetic markers for streptococcal infection at different tissue sites in the human host (skin, throat).In this report, the impact of orthologous gene replacement targeting the nra/rofA locus is experimentally addressed. Replacement of the native nra-lineage allele with a rofA-lineage allele, plus their respective upstream regions, preserved the polarity of Nra effects on pilus gene transcription (i.e., activation) in the skin strain Alab49. Increased pilus gene transcription in the rofA chimera correlated with a higher rate of bacterial growth at the skin. The transcriptional regulator MsmR, which represses nra and pilus gene transcription in the Alab49 parent strain, has a slight activating effect on pilus gene expression in the rofA chimera construct.Data show that exchange of orthologous forms of a regulatory gene is stable and robust, and pathogenicity is preserved. Yet, new phenotypes may also be introduced by altering the circuitry within a complex transcriptional regulatory network. It is proposed that orthologous gene replacement via interspecies exchange is an important mechanism in the evolution of highly recombining bacteria such as S. pyogenes