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In patients with unexplained syncope, bifascicular block (BFB) is considered associated with syncope due to either heart block or sinus arrest. Immediate or delayed pacemaker (PM) implantation after ECG documentation of syncopal recurrence by means of implantable cardiac monitors (ICM) is still debated. We aimed to assess the incidence of recurrent syncope and guideline-based PM implantation in patients with syncope and BFB implanted with ICM.Consecutive patients with syncope and BFB followed at two tertiary care syncope units and implanted with ICM from 2012 to 2020 were retrospectively reviewed. Only patients with ≥2 clinical visits and ≥ 18 years of age were included. Incidence of a Class I indication for PM implantation was the primary outcome.Of 635 syncope patients implanted with an ICM, 55 (8.7%) had a BFB and were included. Median age at implantation was 75 [interquartile range, IQR:64-81] years, and 28(49.1%) were women. At 26 [IQR:12-41] months follow-up, 20 (36.3%,16.3%/year) patients experienced syncope: in 6(10.9%) patients syncope was classified 'arrhythmic' with a higher prevalence in older individuals (p = 0.048). PM implantation (N = 14,25.5%) was more frequent in patients ≥75 years (p = 0.024). At survival analysis, patients ≥75 years were at highest risk of arrhythmic syncope and guideline directed PM implantation (Hazard Ratio: 4.5, 95% Confidence Intervals 1.5-13.3).Most older patients with syncope who received an ICM did not have events during follow-up. One-in-three experienced syncope, and an even smaller number had an arrhythmic syncope with indication for PM implantation. Older age was strongly associated with PM implantation.

This paper is the second in a series of two that deal with a generalized theory of nonlocal elasticity of n-Helmholtz type. This terminology is motivated by the fact that the attenuation function (kernel) of the integral type nonlocal constitutive equation is the Green function associated with a generalized Helmholtz differential operator of order n. In the first paper, the governing equations have been derived and supported by suitable thermodynamic arguments. In this second paper, the proposed nonlocal model is specialized for the one-dimensional case to solve boundary-value problems. First, the relevant higher-order nonstandard boundary conditions in the differential (or, more precisely, integro-differential) version of the theory are derived. These boundary conditions are consistent with the particular family of attenuation functions adopted in the integral formulation. Then, some simple applications to statics and dynamics problems are presented. In particular, the theory is used to capture the static response and to perform free vibration analysis of a discrete lattice model with periodic microstructure (mass-and-spring chain) featured by nearest neighbor and next nearest neighbor particle interactions. In the latter case, boundary effects arise at the two lattice ends that are well captured by the proposed nonlocal continuum formulation. The nonlocal material parameters are identified a priori by matching the dispersion curve of the discrete lattice model, and a comparison in terms of attenuation function is also presented.

Background Subcutaneous implantable cardioverter-defibrillators (S-ICDs) are attractive for preventing sudden cardiac death in hypertrophic cardiomyopathy (HCM) as they mitigate risks of transvenous leads in young patients. However, S-ICDs may be associated with increased inappropriate shock (IAS) in HCM patients. Objective The purpose of this study was to assess the incidence and predictors of appropriate shock and IAS in a contemporary HCM S-ICD cohort. Methods We collected electrocardiographic and clinical data from HCM patients who underwent S-ICD implantation at 4 centers. Etiologies of all S-ICD shocks were adjudicated. We used Firth penalized logistic regression to derive adjusted odds ratios (aORs) for predictors of IAS. Results Eighty-eight HCM patients received S-ICDs (81 for primary and 7 for secondary prevention) with a mean follow-up of 2.7 years. Five patients (5.7%) had 9 IAS episodes (3.8 IAS per 100 patient-years) most often because of sinus tachycardia and/or T-wave oversensing. Independent predictors of IAS were higher 12-lead electrocardiographic R-wave amplitude (aOR 2.55 per 1 mV; 95% confidence interval 1.15–6.38) and abnormal T-wave inversions (aOR 0.16; 95% confidence interval 0.02–0.97). There were 2 appropriate shocks in 7 secondary prevention patients and none in 81 primary prevention patients, despite 96% meeting Enhanced American College of Cardiology/American Heart Association criteria and the mean European HCM Risk-SCD score predicting 5.7% 5-year risk. No patients had sudden death or untreated sustained ventricular arrhythmias. Conclusion In this multicenter HCM S-ICD study, IAS were rare and appropriate shocks confined to secondary prevention patients. The R-wave amplitude increased IAS risk, whereas T-wave inversions were protective. HCM primary prevention implantable cardioverter-defibrillator guidelines overestimated the risk of appropriate shocks in our cohort.

Background and purpose We sought to investigate whether there are gender differences in clinical outcome after stroke due to large vessel occlusion (LVO) after mechanical thrombectomy (EVT) in a large population of real-world patients. Methods From the Italian Registry of Endovascular Thrombectomy, we extracted clinical and outcome data of patients treated for stroke due to large vessel occlusion. We compared clinical and safety outcomes in men and women who underwent EVT alone or in combination with intravenous thrombolysis (IVT) in the total population and in a Propensity Score matched set. Results Among 3422 patients included in the study, 1801 (52.6%) were women. Despite older age at onset (mean 72.4 vs 68.7; p Conclusions Subject to the limitations of a non-randomized comparison, women with stroke due to LVO treated with mechanical thrombectomy had a better chance to achieve complete recanalization, and 3-month functional independence than men. The results could be driven by women who underwent combined treatment.

Funding Acknowledgements Type of funding sources: None. Background A high incidence of pulmonary vein (PV) reconnection has been reported in patients with clinical recurrences of AF. Detailed characterization of PV gaps in terms of local impedance (LI) is still lacking. Purpose to characterize PV gaps with a novel local impedance algorithm during redo PV ablation in AF patients (pts). Methods Consecutive pts undergoing repeated AF ablation from the CHARISMA registry with complete characterization of PV gaps through local impedance at 6 Italian centers were included. A complete map of the left atrium and PVs was performed prior and after ablation through the Rhythmia mapping system. A novel RF ablation catheter with dedicated algorithm (DirectSense) was used to measure LI at the distal electrode of this catheter. Each gap was characterized in terms of LI and its variations during ablation procedure according to different ablation sites around the PVs. 7 sites around the left and right pair of PV for LI evaluation during ablation were defined: 2 for posterior sites (PS) (posterior inferior and posterior superior), 2 for anterior sites (AN) (anterior inferior and anterior superior), 1 for interior site (INF), 1 for superior site (SUP) and 1 for the carina (CAR). Ablation endpoint was PVI as assessed by entrance and exit block. Results Eighteen cases of redo AF ablation were analyzed (9 after prior RF ablation, 9 after prior cryoablation). A total of 41 PV gaps were detected (20 after RF ablation, 21 after cryoablation; mean number of gaps per pt = 2.3 ± 1.1): one gap was identified In five (27.8%) pts, 2 gaps were present in 7 (38.9%) pts, 3 gaps were detected in 2 (11.1%) pts and 4 gaps were identified in the remaining 4 (22.2%) pts. PV gaps were most common at AN sites (17, 41.5%), followed by PS sites (12, 29.3%) and CAR sites (11, 28.6%). The mean LI at gap sites was 113.9 ± 15Ω prior to ablation: it was significantly higher than LI at scar tissue closer to gap (99.7 ± 8Ω, p Conclusion In our preliminary experience, PV gaps after failed PVI were most common at anterior, followed by posterior and carina sites. LI characteristics at PV gaps significantly differ from both scar and healthy tissue and could be used to target ablation deliveries.

Concrete behaves as a brittle material due to its low inherent tensile strength, but it can also exhibit a markedly ductile behavior when coupled with transverse reinforcement like steel stirrups. The role of stirrups is to enhance confinement effect, to restrain the lateral expansion of concrete, thus modifying the concrete stress-strain constitutive law and enabling higher compression strains and higher ductility. This paper focuses on the confinement effect induced by different arrangements of transverse reinforcement on axially loaded concrete columns. An experimental campaign has been carried out, comprising 18 concrete columns with two different mechanical strengths and reinforced with three different layouts of stirrups, namely typical closed square hoops, closed stirrups with additional cross ties, and a novel type of stirrups involving rectangular hoops with additional restraint plates, the latter offering an enhanced diffused confinement action and limiting extensive spalling of the cover concrete. Formation and propagation of longitudinal micro-cracks are reduced with the novel type of diffused stirrups and a moderate-to-high increase of ductility is observed. However, the beneficial effects induced by diffused stirrups are more pronounced in medium-strength concrete and almost negligible in low-strength concrete that collapses due to a brittle cracking failure without involving the confinement action of the transverse reinforcement.

Purpose To evaluate any possible correlation between the presence of Isocitrate DeHydrogenase 1 mutation (IDH1m) and specific DTI (Diffusion Tensor Imaging) metrics, such as Fractional Anisotropy (FA), Mean Diffusivity (MD), Radial Diffusivity (RD) and Axial Diffusivity (AD). Methods We retrospectively analyzed 47 patients who underwent an advanced-MR study with DTI followed by surgical intervention with a subsequent histologic diagnosis of High-Grade Glioma (HGG) and immunohistochemical evaluation of IDH1 (Isocitrate DeHydrogenase) mutation status. For each DTI metrics we measured the ratio between tumor and normal tissue and we evaluated the correlation with IDH1 mutation. Results We observed a positive correlation with IDH1 status and RD and MD data. No correlation was demonstrated between IDH1 status and FA and AD. Discussion Our results support the hypothesis that the number of residual axonal fibers, extracellular matrix composition and the presence of colliquated tissue, may together contribute to a global RD increase in HGG, with a relatively higher increase in IDH1m tumors. Conclusions Our data are in favor of a need for multimodal advance evaluation of HGG. DTI metrics help to analyze IDH1 mutation status, in order to better characterize the lesions and to tailor treatment and follow up.

Aims Per standard of care, dual-chamber pacemakers are programmed in DDDR mode with fixed atrioventricular (AV) delay or with long AV delay to minimize ventricular pacing. We aimed to evaluate whether the PR interval may be a specific criterion of choice between standard DDDR, to preserve AV synchrony in long PR patients, and managed ventricular pacing (MVP), to avoid ventricular desynchronization imposed by right ventricle apical pacing, in short PR patients. Methods and results In the MINERVA trial, 1166 patients were randomized to Control DDDR, MVP, or atrial anti-tachycardia pacing plus MVP (DDDRP + MVP). We evaluated the interaction of PR interval with pacing mode by comparing the risk of atrial fibrillation (AF) longer than 7 consecutive days as a function of PR interval. Out of 906 patients with available data, the median PR interval was 180 ms. The PR interval was found to significantly (P = 0.012) interact with pacing mode for AF incidence: the risk of AF > 7 days was lower [hazard ratio (HR) 0.58, 95% confidence interval (95% CI) 0.34-0.99; P = 0.047] in patients with short PR (shorter than median PR) if programmed in MVP mode compared with DDDR mode and it was lower (HR 0.65, 95% CI 0.43-0.99; P = 0.049) in patients with long PR (equal to or longer than median PR) if programmed in DDDR mode compared with MVP. Conclusion Our data show that PR interval may be used as a selection criterion to identify the optimal physiological pacing mode. Persistent AF incidence was lower in short PR patients treated by right ventricular pacing minimization and in long PR patients treated by standard dual-chamber pacing.

The fracture behavior of lightweight foamed concrete (LWFC) is significantly influenced by microstructural properties, which are ascribed to the arrangement of air bubbles and pores as well as to the presence of different hydration products. In this contribution, an experimental investigation on the fracture behavior of LWFC is performed. Notched beams made of LWFC were tested in three-point bending to determine the fracture energy based on the load-CMOD (Crack Mouth Opening Displacement) curve. The influence of the dry density is explored considering one density for non-structural purposes (equal to 800 kg/m3) and another density for structural applications (1600 kg/m3). Moreover, two curing conditions are considered (air and water). The load-CMOD curves reveal that for lower dry densities the fracture behavior of LWFC is particularly affected by the curing conditions, with better results achieved in air curing conditions, but this influence decreases with higher dry densities. The improved performance in air curing conditions for lower dry densities is also observed in terms of flexural strength, but is not particularly evident for the compressive strength. Micrographs across the crack surface determined via Scanning Electron Microscopy (SEM) are finally presented to analyze the experimental findings and justify the results in terms of microstructural configuration of the specimens.

The earthquake protection of structures equipped with energy dissipation devices in the form of nonlinear fluid viscous dampers (FVDs) is investigated. Most of the optimal design strategies from the literature either address a simplified linear (Newtonian) idealization of the devices, or identify the characteristics of the nonlinear FVDs in a later stage, by invoking the concept of “energy-equivalent” dampers to compromise between the nonlinear power law force-velocity behavior and a simplified (equivalent, in terms of energy dissipation) linear modeling. In this paper, the nonlinear power law behavior of the devices is incorporated a priori in the optimal design process. The proposed strategy, based upon a numerical approach to a constrained optimization problem, invokes a performance criterion that is derived from the energy balance equation of the system, expressed in stochastic terms. To handle the nonlinear constitutive behavior of the FVDs, a novel equal-energy non-Gaussian stochastic linearization technique is integrated in the optimal design process. For a given power-spectral-density function of the seismic excitation, the most effective set of nonlinear FVDs that maximize the energy dissipation behavior can be identified. By stochastic dynamic analysis and by nonlinear response-history-analysis with an ensemble of ground motions, the proposed energy-based design philosophy is found to be better able to control the overall seismic response of the structure than alternative procedures that are not based on energy concepts and that minimize other performance indices.

It is hotly debated whose perspective is relevant for defining the truth-value of bare epistemic possibility statements: the utterer or the assessor. Central to this debate are findings on truth-value judgments of ‘might p’ statements in “eavesdropping” scenarios where the statement is appropriately asserted from the point of view of the speaker but does not correspond to how in reality things are. We offer findings from two studies suggesting that in these scenarios English speakers disagree on the truth-value not only of ‘might p’ but also, surprisingly, of bare ‘p’. We argue that underlying this behavior is not a disagreement on the semantic content of the statements but a disagreement on how to interpret the meaning of the adjectives ‘true’ and ‘false’ when applied to a statement uttered by another agent. Specifically, we compare two potential accounts: the first account ascribes to the adjective ‘true’ an ambiguity between a ‘coherent’ sense – a statement uttered by A is true as long as the statement coheres with A’s evidence – and a ‘correspondentist’ sense - a statement as uttered by A is true as long as the statement correspond to reality; the second account treats ‘true’ as having only the correspondentist sense but ascribes to it an inherent relative nature – to decide if a statement as uttered by A is true one has to first decide a perspective (A or the assessor). Lastly, we discuss the implications of the findings for the semantics of epistemic ‘might p’ statements.

BACKGROUND: Cardiac implantable electronic devices (CIEDs) are widely used to treat bradyarrhythmias or improve the prognosis of patients with heart failure (HF). AIMS: To evaluate age-related (≤ 75 vs. > 75 years) attitudes, worries, psychological effects and needs in an Italian CIEDs population. METHODS: Patients attending their periodical ambulatory evaluation received a questionnaire conceived by the European Heart Rhythm Association Scientific Initiatives Committee as part of a multicenter, multinational snapshot survey. Seven countries participated in the study, and 1646 replies were collected. Of these, 437 (27%) were from Italy. Present results refer to the Italian population only. CIEDs were stratified into devices to treat bradycardia or HF. RESULTS: The use of CIEDs was more common in advanced age. Older patients needed less information about CIEDs than younger ones (p = 0.044), who would prefer to be better informed about CIEDs-related consequences on psychologic profile (p = 0.045), physical (p

The technique of direct intratumoral injection of permanent liquid agents has evolved significantly over the past few decades. The percutaneous direct puncture technique is being utilised more and more for embolisation of head and neck hypervascular lesions. We describe a case treated via the direct percutaneous transnasal (TN) puncture technique for embolisation of a sinonasal hypervascular tumour, performed in a 21-year-old male patient. Due to extensive vascularisation of the tumour, preoperative embolisation was requested by our otolaryngologist team in order to minimise intraoperative bleeding and reduce surgical morbidity. A primary attempt at trans-arterial embolisation through selective ophthalmic artery catheterisation was unsuccessful due to unfavourable anatomy. An extensive devascularisation of the nasal fossa lesion was obtained using a single injection of low-density polymeric embolic agent (SQUID®). Post-operative eradication was uneventful. Final histopathology exam revealed vascular tumour consistent with a rare sinonasal glomangiopericytoma. To our knowledge, this is the first reported case of a rare sinonasal glomangiopericytoma treated by direct TN injection, utilising the liquid polymer agent SQUID®.

Background: More and more heart failure (HF) patients aged ≥ 75 years undergo cardiac resynchronization therapy (CRT) device implantation, however the data regarding the outcomes and their predictors are scant. We investigated the mid- to long-term outcomes and their predictors in CRT patients aged ≥ 75 years. Methods: Patients in the Cardiac Resynchronization Therapy Modular (CRT MORE) Registry were divided into three age-groups: &lt, 65 (group A), 65–74 (group B) and ≥75 years (group C). Mortality, hospitalization, and composite event rate were evaluated at 1 year and during long-term follow-up. Results: Patients (n = 934) were distributed as follows: group A 242, group B 347, group C 345. On 12-month follow-up examination, 63% of patients ≥ 75 years displayed a positive clinical response. Mortality was significantly higher in patients ≥ 75 years than in the other two groups, although the rate of hospitalizations for HF worsening was similar to that of patients aged 65–74 (7 vs. 9.5%, respectively, p = 0.15). Independent predictors of death and of negative clinical response were age &gt, 80 years, chronic obstructive pulmonary disease (COPD) and chronic kidney disease (CKD). Over long-term follow-up (1020 days (IQR 680-1362)) mortality was higher in patients ≥ 75 years than in the other two groups. Hospitalization and composite event rates were similar in patients ≥ 75 years and those aged 65–74 (9 vs. 11.8%, p = 0.26, and 26.7 vs. 20.5%, p = 0.06). Conclusion: Positive clinical response and hospitalization rates do not differ between CRT recipients ≥ 75 years and those aged 65–74. However, age &gt, 80 years, COPD and CKD are predictors of worse outcomes.

BACKGROUND AND PURPOSE: Intra-arterial DSA has been traditionally used for confirmation of cure following gamma knife radiosurgery for AVMs. Our aim was to evaluate whether 4D arterial spin-labeling MRA and contrast-enhanced time-resolved MRA in combination can be an alternative to DSA for confirmation of AVM obliteration following gamma knife radiosurgery. MATERIALS AND METHODS: In this prospective study, 30 patients undergoing DSA for confirmation of obliteration following gamma knife radiosurgery for AVMs (criterion standard) also underwent MRA, including arterial spin-labeling MRA and contrast-enhanced time-resolved MRA. One dataset was technically unsatisfactory, and the case was excluded. The DSA and MRA datasets of 29 patients were independently and blindly evaluated by 2 observers regarding the presence/absence of residual AVMs. RESULTS: The mean time between gamma knife radiosurgery and follow-up DSA/MRA was 53 months (95% CI, 42–64 months; range, 22–168 months). MRA total scanning time was 9 minutes and 17 seconds. Residual AVMs were detected on DSA in 9 subjects (obliteration rate = 69%). All residual AVMs were detected on at least 1 MRA sequence. Arterial spin-labeling MRA and contrast-enhanced time-resolved MRA showed excellent specificity and positive predictive values individually (100%). However, their sensitivity and negative predictive values were suboptimal due to 1 false-negative with arterial spin-labeling MRA and 2 with contrast-enhanced time-resolved MRA (sensitivity = 88% and 77%, negative predictive values = 95% and 90%, respectively). Both sensitivity and negative predictive values increased to 100% if a composite assessment of both MRA sequences was performed. Diagnostic accuracy (receiver operating characteristic) and agreement (κ) are maximized using arterial spin-labeling MRA and contrast-enhanced time-resolved MRA in combination (area under receiver operating characteristic curve = 1, P

Water is very important for human consumption, production and services and also for inspiration, recreation, landscapes, ecosystems and wild life. UN and EU policies highlights the interaction of historical scientific, economic, societal and environmental factors and the linkage of water policies with biodiversity protection and Climate Change adaptation. According to the European Green Deal (2019), for a fair and prosperous society, with a modern, resource-efficient and competitive economy working across sectors and disciplines, will be needed, also involving local communities. Moreover Political and management processes may take benefits from specific participatory Tools.The Emilia-Romagna Regional Agency for Prevention, Environment and Energy (Arpae) helps sustainability developing actions for water protection, water use, flood management and education to sustainability. Arpae Hydrological Service (HS) supports flood management and water management, as also design and management of hydraulic structures, through the Flood Early Warning System FEWS and the Drought Early Warning System DEWS. Arpae HS also collect and publish hydrological time series (water, solid transport) and stage-discharge equations.Within FP7 Enhance (2017) multi risk analysis and Public Private Partnership (PPPs) experiences were supported by modeling tools combining flood /earthquake/Climate Change scenarios in a densely populated, highly developed land reclamation territory. An Application of the System for Economic and Environmental Accounting for Water (UN SEEA -Water) was developed in 2017. Within Interreg Proline-CE (2019), the FEWS and DEWS Systems, respectively supporting the Flood Forecasting Center and the Observatory on Water Uses, were proposed as Best Management Practices (BMPs) for land and water management useful for drinking water protection. BMPs where tested through workshops, questionnaires, meetings and technical visits, useful for dissemination and stakeholders involvement. H2020 Clara was useful to experience co-design/co-development approaches, to explore market segments and business models for water knowledge and climate services, and to set dedicated Policy Briefs for Water and Climate Change Adaptation; Arpae HS developed a set of modeling services (Clara PWA) related to water management, solid transport, water quality and habitat availability, useful to understand the influenced of climate change and the needs and proposal coming from market and the institutions. Interreg boDEREC-CE is a current project on pharmaceutical and personal care pollutants (PPCPs), aimed at developing tools and strategies for protection of drinking water, water ecosystems and public health from pollution, bacterial resistance, toxicity and pathogens.Arpae HS through these experiences has gained awareness of the inter linkage of hydrology with other sectors (economy, Earth sciences, ICT, health, ecology, society) and of the importance of developing specific decision support tools maximizing stakeholder participation, societal dissemination, transparency, education to sustainability and experts involvement.

Digital Image Correlation (DIC) provides measurements without disturbing the specimen, which is a major advantage over contact methods. Additionally, DIC techniques provide full-field maps of response quantities like strains and displacements, unlike traditional methods that are limited to a local investigation. In this work, an experimental application of DIC is presented to investigate a problem of relevant interest in the civil engineering field, namely the interface behavior between externally bonded fabric reinforced cementitious mortar (FRCM) sheets and concrete substrate. This represents a widespread strengthening technique of existing reinforced concrete structures, but its effectiveness is strongly related to the bond behavior between composite fabric and underlying concrete. To investigate this phenomenon, a set of notched concrete beams are realized, reinforced with FRCM sheets on the bottom face, subsequently cured in different environmental conditions (humidity and temperature) and finally tested up to failure under three-point bending. Mechanical tests are carried out vis-à-vis DIC measurements using two distinct cameras simultaneously, one focused on the concrete front face and another focused on the FRCM-concrete interface. This experimental setup makes it possible to interpret the mechanical behavior and failure mode of the specimens not only from a traditional macroscopic viewpoint but also under a local perspective concerning the evolution of the strain distribution at the FRCM-concrete interface obtained by DIC in the pre- and postcracking phase.

Magnetic resonance imaging is the reference standard for targeting lesions in radiosurgery. Computerized tomography is mandatory in systems based on linear accelerators and a useful adjunct in selected cases in gamma beam-based systems. Image registration can help implement information from different imaging systems but must be managed with care acknowledging its intrinsic limits and dangers that may differ in different systems and software versions. Advanced magnetic resonance imaging techniques and PET are some of the tools that can provide important additional data. Meningiomas situated in specific locations pose some diagnostic challenges that must be overcome with tailored sequences. Among those, fat-suppressed sequences are very useful in the study of basicranial and intraorbital meningiomas. Heavily T2-weighted volumetric imaging is very useful to delineate margins of meningiomas in the cavernous sinus or anterior posterior fossa. Atypical meningiomas represent a challenge both from a treatment strategy and diagnostic point of view. Several advanced imaging techniques have been used to identify atypical lesions in the preoperative phase, but up to date no single technique or specific combination of techniques can provide a precise non-invasive diagnosis. Characteristics of meningiomas most commonly associated with malignant composition are summarized.

Due to the close proximity of cavernous sinus meningiomas (CSMNs) to vital intracranial neurovascular structures, complete surgical resection may not always be possible. Hence, stereotactic radiosurgery (SRS) has been proposed as a primary, adjuvant and/or salvage treatment option for the management of such cases. The aims of this study were to assess the long-term outcomes of SRS on a large patient series and to identify any prognosticators significantly influencing local tumour control (LTC).

A generalized theory of nonlocal elasticity is elaborated. The proposed integral type nonlocal formulation is based on attenuation functions being assumed as the convolution product of n first order (Eringen type) kernels. The theory stems from a generalized higher-order constitutive relation between the nonlocal stress and the local strain. Inspired by the Eringen two-phase local/nonlocal integral model, this theory can also be thought of as the constitutive relation for an (n + 1)-phase material, in which one phase has local elastic behavior, and the remaining n phases comply with nonlocal elasticity of higher order. The theory is supported by a suitable thermodynamic framework. In the spirit of Eringen’s 1983 paper, the particular family of attenuation functions adopted are the Green functions associated with generalized Helmholtz type differential operators of order n —which suggests denoting this model as a generalized nonlocal elasticity theory of n-Helmholtz type. Besides the integral type nonlocal formulation, elegant and compact expressions for the differential and integro-differential counterpart are derived. For n = 1 this formulation straightforwardly leads to the Aifantis 2003 implicit gradient elasticity theory with simultaneous stress gradients and strain gradients, which was postulated to eliminate stress and strain singularities from crack tips and dislocation lines. For n = 2 an implicit gradient elasticity formulation with bi-Helmholtz type stress and strain gradients is obtained. The paper is complemented by a companion Part II on the particularization of the generalized theory of nonlocal elasticity for the one-dimensional case, along with some applications in statics and dynamics.

Digital Image Correlation (DIC) techniques have significant advantages in structural health monitoring compared to local measurements, being a non-contact method and providing distribution of engineering response indicators such as strains and displacements. In this paper, DIC is applied to investigate the bond behavior between Externally Bonded (EB) Fiber-Reinforced Cementitious Matrix (FRCM) fabric and concrete substrate. This is a popular strengthening technique for retrofitting existing concrete structures. Considering the different failure modes observed at the interface (e.g. cohesive debonding of concrete substrate, detachment at matrix-to-substrate interface, fiber sliding within the matrix, fiber rupture, etc.), a critical issue is to investigate the bond behavior of the EB composite fabric. To this aim, a series of concrete notched beams are prepared with the EB composite fabric applied onto the bottom face of the specimen and tested under three-point-bending. Results from the DIC measurements in two regions of interest of the beam, namely in the concrete area above the notch and at the FRCM-concrete interface, are then discussed and critically interpreted based on the observed macroscopic mechanical behavior and corresponding force-displacement curves. These outcomes are useful to identify the attainment of the concrete material strength, as well as the failure mode of the beam, and to investigate the stress transfer propagation at the FRCM-concrete interface. Moreover, DIC investigation may be potentially useful to anticipate the incipient crack development.