Search

BackgroundThe coronavirus disease 2019 (COVID-19) pandemic drastically altered children's activity patterns. Our goal was to investigate how COVID-19 affected demographics, injury characteristics, treatment patterns, follow-up, and outcomes in pediatric supracondylar humerus (SCH) fractures.MethodsThis was an Institutional Review Board-approved retrospective analysis of patients undergoing surgery for a SCH fracture from May to November 2019 (pre-COVID-19) and from May to November 2020 (during COVID-19) at 2 tertiary children's hospitals. Demographic information, injury characteristics, hospital course, and follow-up data were collected and compared.ResultsSCH fractures decreased by >50% from 2019 (149) to 2020 (72). Children in the 2020 cohort were younger (mean 5.2y old) compared with 2019 (6.0y old) ( P =0.019). Mechanism of injury was significantly different in 2020 ( P

BACKGROUND AND AIMS Peroxisome proliferator-activated receptor (PPAR)-γ agonists decrease hepatic/visceral fat (VF) and improve necroinflammation despite subcutaneous (SC) fat weight-gain. Understanding the impact of changes in VF, VF-to-SC fat distribution (VF/SC) and adiponectin (ADPN) levels in relation to histological improvement after weight-loss or pioglitazone is relevant as novel PPAR-γ agonists are being developed for treating non-alcoholic steatohepatitis (NASH). METHODS Fifty-five patients with NASH received a -500 kcal/d hypocaloric diet and were randomized (double-blind) to pioglitazone (45 mg/d) or placebo for 6-months. Before and after treatment patients underwent a liver biopsy and measurement of hepatic/peripheral glucose fluxes, hepatic/adipose tissue-IR and, in 35 patients, hepatic and VF/SC-fat was measured by magnetic resonance spectroscopy/imaging. Data were examined by multivariable statistical analyses combined with machine-learning techniques (partial least square discriminant analysis [PLS-DA]). RESULTS Both pioglitazone (despite weight-gain) and placebo (if weight-loss) reduced steatosis but only pioglitazone ameliorated necroinflammation. Using machine-learning PLS-DA showed that the treatment differences induced by a PPAR-γ agonist vs placebo on metabolic variables and liver histology could be best explained by the increase in ADPN and a decrease in VF/SC, and to a lesser degree, improvement in oral glucose tolerance test-glucose concentrations and ALT. Decrease in steatosis and disease activity score (ballooning plus lobular inflammation) kept a close relationship with an increase in ADPN (r = -.71 and r = -.44, P

The purpose of this scoping review was to examine the nature and quality of research regarding paediatric supracondylar humerus (SCH) fractures in low and lower middle-income countries (LICs). We searched PubMed, Embase, Web of Science, and African Journals Online on January 9, 2018, for studies of SCH fractures in LICs. Studies were categorized by geographic region, Gartland classification of included patients, and study design. We evaluated each study’s methodology and conclusions. Out of 1805 results, we analyzed 105 studies, most of which included type 3 fractures only (66%). Many were conducted in South Asia (58%) and assessed treatment outcomes (78%). Most of the studies had level IV evidence (67%). Common limitations of research were small sample size (12%) and inadequate follow-up (6%). Epidemiological studies concluded that SCH fractures are more common among male children, are usually secondary to falls, and rarely present with nerve injuries. Most therapeutic studies reported outcomes of surgery (91%). Thirteen studies concluded that all-lateral versus cross-pinning techniques have similar outcomes. Seven studies reported preference for closed reduction over open reduction, when intra-operative fluoroscopy was available. Most common outcome measures were Flynn criteria (77%) and range of motion (53%). None of the papers looked at treatment costs. Our data show a predominance of small level IV studies from LICs, with few studies of higher level of evidence. Many studies examined controversies with surgical technique, similar to studies performed in high-income countries. Few studies examined non-operative treatment, which is commonly the predominant treatment available for patients in LICs. Further investigation of common treatment modalities and outcomes for SCH fractures in LICs is needed.

Background & Aims The I148M Patatin-like Phospholipase Domain-containing 3 (PNPLA3), the rs641738 in the Membrane bound O-acyltransferase domain containing 7-transmembrane channel-like 4 (MBOAT7-TMC4) locus, and the E167K Transmembrane 6 Superfamily Member 2 (TM6SF2) polymorphisms represent the main predisposing factors to nonalcoholic fatty liver disease (NAFLD) development and progression. We previously generated a full knockout of MBOAT7 in HepG2 cells (MBOAT7-/-), homozygous for I148M PNPLA3. Therefore, we aimed to investigate the synergic impact of the 3 at-risk variants on liver injury and hepatocellular carcinoma (HCC) in a large cohort of NAFLD patients, and create in vitro models of genetic NAFLD by silencing TM6SF2 in both HepG2 and MBOAT7-/- cells. Methods NAFLD patients (n = 1380), of whom 121 had HCC, were stratified with a semiquantitative score ranging from 0 to 3 according to the number of PNPLA3, TM6SF2, and MBOAT7 at-risk variants. TM6SF2 was silenced in HepG2 (TM6SF2-/-) and MBOAT7-/- (MBOAT7-/-TM6SF2-/-) through Clustered regularly interspaced short palindromic repeats and CRISPR-associated protein 9 (CRISPR/Cas9). Results In NAFLD patients, the additive weight of these mutations was associated with liver disease severity and an increased risk of developing HCC. In HepG2 cells, TM6SF2 silencing altered lipid composition and induced the accumulation of microvesicular lipid droplets (LDs), whereas the MBOAT7-/-TM6SF2-/- cells showed a mixed microvesicular/macrovesicular pattern of LDs. TM6SF2 deletion strongly affected endoplasmic reticulum and mitochondria ultrastructures, thus increasing endoplasmic reticulum/oxidative stress. The mitochondrial number was increased in both TM6SF2-/- and MBOAT7-/-TM6SF2-/- models, suggesting an unbalancing in mitochondrial dynamics, and the silencing of both MBOAT7 and TM6SF2 impaired mitochondrial activity with a shift toward anaerobic glycolysis. MBOAT7-/-TM6SF2-/- cells also showed the highest proliferation rate. Finally, the re-overexpression of MBOAT7 and/or TM6SF2 reversed the metabolic and tumorigenic features observed in the compound knockout model. Conclusions The co-presence of the 3 at-risk variants impacts the NAFLD course in both patients and experimental models, affecting LD accumulation, mitochondrial functionality, and metabolic reprogramming toward HCC., Graphical abstract

Purpose: There has been a recent shift towards operative management of mid-shaft clavicle fractures in adults and adolescents. This has been largely based on studies in the adult population that showed reduced rates of nonunion, symptomatic malunion and better short-term functional outcomes. For injuries with a comminuted “Z-type” fracture pattern, characterized by vertical positioning of a segmental fragment, it is commonly accepted to treat surgically due to concerns about healing and bony prominence. The purpose of this study was to assess the clinical, radiographic, and patient-reported outcome measures (PROs) in adolescents with comminuted Z-type mid-shaft clavicle fractures by comparing an operative and nonoperative cohort. Methods: Patients aged 10 to 18 years treated for a diaphyseal clavicle fracture between August 2013 and February 2016 at one of eight geographically diverse pediatric centers were screened and enrolled at the time of injury. Inclusion criteria were a comminuted Z-type fragment ≥1cm in size, with >35 degrees of angulation relative to the long axis of the clavicle, and >100% fracture displacement at time of presentation. Clinical course, complications, validated PROs, quality of life metrics, and satisfaction scores were analyzed and compared between the operative (Op) and nonoperative (NonOp) cohorts. Results: Eighty-two patients (37 NonOp, 45 Op) were included, 60 (73%) of whom provided 2-year PROs with similar response rates between treatment cohorts. There were no significant differences in demographics or fracture characteristics in the two cohorts other than fracture shortening being greater in the operative cohort (mean 29mm) compared to the nonoperative cohort (mean 23mm, p=0.01). This confounder was controlled for in both regression analysis and propensity score matching. There was no statistically significant difference in the rates of nonunion (none), delayed union (Op 2%, NonOp 0%, p=1.0), symptomatic malunion (Op 0%, NonOp 3%, p=0.4), refracture (Op 4%, NonOp 3%, p=1.0), unexpected surgery (Op 11% vs. NonOp 5%, p=0.45), or clinically significant complications (Op 16%, NonOp 5%, p=0.17) between cohorts. There were no differences in PROs (Table 1), even when controlling for fracture shortening. Conclusions: Z-type mid-shaft clavicle fractures are one of the most severe fracture patterns seen in adolescent shoulders. Yet, in this comparative investigation of 2-year PROs and complications, surgery appears to offer no benefit over nonoperative management. Significance: The comparable natural histories between this study’s operative and nonoperative cohorts are critical for surgeons and their adolescent patients to understand when deciding appropriate management, particularly when reviewing what are often very concerning appearing initial radiographs.

Objectives: Operative management of clavicle fractures is increasingly advocated for athletes and young adults. Surgical indications and optimal treatment for comminuted or severely shortened clavicle fractures in adolescent athletes remain unclear. The purpose of this study was to evaluate the outcomes of non-operatively and operatively treated comminuted and/or severely shortened (>25mm) clavicle fractures in older adolescent athletes. Methods: Athletes aged 14 to 18 years with mid-shaft clavicle fractures who had non-operative (NONOP) or operative (OP) treatment at one of eight participating centers between 2013 and 2017 were screened for the presence of comminution and/or fracture shortening >25mm. Demographics, injury mechanism, fracture characteristics and treatment (NONOP vs. OP) were prospectively recorded and patients followed for a minimum of two years. Complications, rates and timing of return to sport (RTS), and patient reported outcomes (PROs: ASES, QuickDASH, MARX shoulder activity, EQ-5D, EQ-VAS, and patient satisfaction) were analyzed. Results: The two groups included 137 patients (70 NONOP, 67 OP), with a similar distribution among various sports—most commonly football—and rates of competitive athletic participation (NONOP: 81%, OP: 85%) (Figure 1). Of the 137 patients, 100 [NONOP n=52, 15.3 years, 44 males (84.6%); OP n= 48, 15.5 years, 40 males (83.3%)] provided PROs at > 2 years. Comminution (C) and shortening (S) were not different between groups [NONOP C=24 (46.2%), S=28mm (24.5, 33.2); OP C=35 (72.9%), S=28mm (25.0, 36.5)], but the OP group demonstrated 3 mm greater vertical displacement [NONOP 13.0 (9.6, 18.0) mm, OP 16.0 (11.8, 21.0) mm; pConclusions: In this prospective multi-center cohort of comminuted and/or severely shortened (>25mm) clavicle fractures in adolescent athletes, there was no difference in complications, RTS, or PROs between non-operatively and operatively treated patients at 2 years. Despite several studies suggesting the contrary in adult populations, comparably excellent outcomes of severe clavicle fractures in adolescent athletes can be achieved with non-operative treatment.

Objectives: We retrospectively assess the potential impact of a novel, investigational Augmented Reality (AR) software application, Radiology with Holographic Augmentation (RadHA), on pediatric orthopedic surgeon's confidence in surgical planning, hardware selection, hardware fit, and estimated potential intraoperative time savings in the setting of complex adolescent elbow fractures.Methods: After study selection, 12 individual cases of complex elbow fractures in adolescent pediatric patients were identified for review. AR models were generated for each case derived from the patient's CT. Five fellowship-trained pediatric orthopedic surgeons reviewed each case for a total of 60 separate observations. Surgeons reviewed clinical data, radiologic imaging, and AR models and then answered Likert Scale questions on measures of confidence in presurgical planning and projected potential time savings. These data were reviewed and analyzed using various statistical tools.Results: Surgeons reported high confidence in the quality of the AR models created. Additionally, surgeons reported increased confidence in their surgical plan, increased confidence in hardware selection, and increased confidence in hardware fit. Within the sub-analysis of complex (comminuted) fractures, surgeons reported greater expected increases in confidence of their surgical plan and hardware fit. Overall, surgeons estimated potential intraoperative time savings, averaging 17.3 min for all fracture types and 17.6 min for complex fractures.Conclusions: Preoperative planning using AR-based models can increase surgeon confidence in preoperative planning, hardware selection, and confidence in hardware fit.

There is a significant unmet need for children’s surgical care in low- and middle-income countries (LMICs). Multidisciplinary collaboration is required to advance the surgical and anesthesia care of children’s surgical conditions such as congenital conditions, cancer and injuries. Nonetheless, there are limited examples of this process from LMICs. We describe the development and 3-year outcomes following a 2015 stakeholders’ meeting in Uganda to catalyze multidisciplinary and multi-institutional collaboration. The stakeholders’ meeting was a daylong conference held in Kampala with local, regional and international collaborators in attendance. Multiple clinical specialties including surgical subspecialists, pediatric anesthesia, perioperative nursing, pediatric oncology and neonatology were represented. Key thematic areas including infrastructure, training and workforce retention, service delivery, and research and advocacy were addressed, and short-term objectives were agreed upon. We reported the 3-year outcomes following the meeting by thematic area. The Pediatric Surgical Foundation was developed following the meeting to formalize coordination between institutions. Through international collaborations, operating room capacity has increased. A pediatric general surgery fellowship has expanded at Mulago and Mbarara hospitals supplemented by an international fellowship in multiple disciplines. Coordinated outreach camps have continued to assist with training and service delivery in rural regional hospitals. Collaborations between disciplines, both within LMICs and with international partners, are required to advance children’s surgery. The unification of stakeholders across clinical disciplines and institutional partnerships can facilitate increased children’s surgical capacity. Such a process may prove useful in other LMICs with a wide range of children’s surgery stakeholders.

PurposeThe purpose of this study is to estimate the burden of musculoskeletal disease among children treated in Kumi District, Uganda, to inform training, capacity-building efforts, and resource allocation.MethodsWe conducted a retrospective cohort study by reviewing the musculoskeletal (MSK) clinic and community outreach logs for children (age

Background:The majority of previous investigations on operative fixation of clavicle fractures have been related to the adult population, with occasional assessments of the younger, more commonly affected adolescent population. Despite limited prospective data for adolescents, the incidence of operative fixation of adolescent diaphyseal clavicle fractures has increased.Purpose:To detail the demographic features and descriptive epidemiology of a large pooled cohort of adolescent patients with diaphyseal clavicle fractures presenting to pediatric tertiary care centers in the United States through an observational, prospective, multicenter cohort study (Function after Adolescent Clavicle Trauma and Surgery [FACTS]).Study Design:Cross-sectional study; Level of evidence, 4.Methods:Patients aged 10 to 18 years who were treated for a diaphyseal clavicle fracture between August 2013 and February 2016 at 1 of 8 geographically diverse, high-volume, tertiary care pediatric centers were screened. Treatment was rendered by any of the pediatric orthopaedic providers at each of the 8 institutions, which totaled more than 50 different providers. Age, sex, race, ethnicity, fracture laterality, hand dominance, mechanism of injury, injury activity, athletic participation, fracture characteristics, and treatment decisions were prospectively recorded in those who were eligible and consented to enroll.Results:A total of 545 patients were included in the cohort. The mean age of the study population was 14.1 ± 2.1 years, and 79% were male. Fractures occurred on the nondominant side (56%) more frequently than the dominant side (44%). Sport was the predominant activity during which the injury occurred (66%), followed by horseplay (12%) and biking (6%). The primary mechanism of injury was a direct blow/hit to the shoulder (60%). Overall, 54% were completely displaced fractures, defined as fractures with no anatomic cortical contact between fragments. Mean shortening within the completely displaced group was 21.9 mm when measuring the distance between fragment ends (end to end) and 12.4 mm when measuring the distance between the fragment end to the corresponding cortical defect (cortex to corresponding cortex) on the other fragment (ie, true shortening). Comminution was present in 18% of all fractures. While 83% of all clavicle fractures were treated nonoperatively, 32% of completely displaced fractures underwent open reduction and internal fixation.Conclusion:Adolescent clavicle fractures occurred more commonly in male patients during sports, secondary to a direct blow to the shoulder, and on the nondominant side. Slightly more than half of these fractures were completely displaced, and approximately one-fifth were comminuted. Within this large cohort, approximately one-third of patients with completely displaced fractures underwent surgery, allowing for future prospective comparative analyses of radiographic, clinical, and functional outcomes.

The accuracy of Monte Carlo simulations in reproducing the scientific performance of space telescopes (e.g. angular resolution) is mandatory for a correct design of the mission. A brand-new Monte Carlo simulator of the Astrorivelatore Gamma ad Immagini LEggero (AGILE)/Gamma-Ray Imaging Detector (GRID) space telescope, AGILESim, is built using the customizable Bologna Geant4 Multi-Mission Simulator (BoGEMMS) architecture and the latest Geant4 library to reproduce the instrument performance of the AGILE/GRID instrument. The Monte Carlo simulation output is digitized in the BoGEMMS postprocessing pipeline, according to the instrument electronic read-out logic, then converted into the onboard data handling format, and finally analyzed by the standard mission on-ground reconstruction pipeline, including the Kalman filter, as a real observation in space. In this paper we focus on the scientific validation of AGILESim, performed by reproducing (i) the conversion efficiency of the tracker planes, (ii) the tracker charge readout distribution measured by the on-ground assembly, integration, and verification activity, and (iii) the point-spread function of in-flight observations of the Vela pulsar in the 100 MeV - 1 GeV energy range. We measure an in-flight angular resolution (FWHM) for Vela-like point sources of $2.0^{+0.2}_{-0.3}$ and $0.8^{+0.1}_{-0.1}$ degrees in the 100 - 300 and 300 - 1000 MeV energy bands, respectively. The successful cross-comparison of the simulation results with the AGILE on-ground and in-space performance validates the BoGEMMS framework for its application to future gamma-ray trackers (e.g. e-ASTROGAM and AMEGO).

Background The objective of this study was to analyze the literature regarding the diagnosis, pathogenesis, and prevalence of gluteal fibrosis (GF) and the outcomes of treatment. Methods We searched PubMed, Embase, and Cochrane literature databases, from database inception to December 15, 2016. We used the following search terms including variants: "contracture," "fibrosis," "injections," "injections, adverse reactions,' "gluteal," and "hip." All titles and abstracts of potentially relevant studies were scanned to determine whether the subject matter was potentially related to GF, using predefined inclusion and exclusion criteria. If the abstract had subject matter involving GF, the paper was selected for review if full text was available. Only papers including ≥10 subjects who underwent surgical treatment were included in the systematic analysis. Data abstracted included the number of patients, patient age and sex, the type of surgical treatment, the method of outcome measurement, and outcomes and complications. Results The literature search yielded 2,512 titles. Of these, 82 had a focus on GF, with 50 papers meeting the inclusion criteria. Of the 50 papers reviewed, 18 addressed surgical outcomes. The surgical techniques in these papers included open, minimally invasive, and arthroscopic release and radiofrequency ablation. Of 3,733 operatively treated patients in 6 reports who were evaluated on the basis of the criteria of Liu et al., 83% were found to have excellent results. Few papers focused on the incidence, prevalence, and natural history of GF, precluding quantitative synthesis of the evidence in these domains. Conclusions This study provided a systematic review of surgical outcomes and a summary of what has been reported on the prevalence, diagnosis, prognosis, and pathogenesis of GF. Although GF has been reported throughout the world, it requires further study to determine the exact etiology, pathogenesis, and appropriate treatment. Surgical outcomes appear satisfactory. Level of evidence Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Background: Progressive displacement of diaphyseal clavicle fractures has been observed in adult patients, at times necessitating a change from non-operative to operative treatment. Whether this occurs in adolescent patients has not been well investigated. Purpose: The purpose of this study was to assess the rate and extent of progressive clavicle fracture displacement in adolescent patients following injury and during the early stages of healing. Methods: This was an IRB approved multi-center study evaluating prospective data that had previously been collected as part of a larger study evaluating the functional outcomes of adolescent clavicle fractures. A consecutive series of completely displaced diaphyseal clavicle fractures in patients age 10-18 years treated at one of three tertiary care pediatric trauma centers were included; all of which had standardized imaging within 2 weeks of the date of injury and throughout the course of healing (5-20 weeks post-injury). Measurements of clavicle shortening, superior displacement, and angulation were performed using validated techniques. Progressive displacement and/or interval improvement in fracture alignment were noted, as well as the subsequent need for surgical intervention. Patient demographic and radiographic parameters were assessed as possible risk factors for interval displacement. Results: One hundred patients met the inclusion criteria. The mean shortening, superior displacement, and angulation at the time of injury were 24 mm, 15 mm, and 7°, respectively. At a mean of 10 weeks post-injury, the fracture alignment improved across all three measurements for the overall cohort, with mean improvements in shortening of 15%, superior displacement of 15%, and angulation of 21% (Figures 1,2,3) Using a clinical threshold of a change in shortening or displacement of 10 mm or angulation of 10 degrees, 21% of fractures improved, 4% worsened, and 75% remain unchanged. Patients with more severe fractures were more likely to have improved alignment than less displaced fractures (pConclusions: Significant early improvements in fracture alignment were observed in a substantial percentage of adolescent patients with completely displaced clavicle fractures. Among the most severely displaced fractures, a 20% improvement in shortening and 50% improvement in angulation was identified. In 4% of cases, increased displacement was observed, but this tended to be mild, and in no cases did it prompt surgical intervention. This finding indicates that the true final deformity after an adolescent clavicle fracture is commonly less than that present at the time of injury. Figures: [Figure: see text][Figure: see text][Figure: see text]

Idiopathic clubfoot has a tremendous worldwide prevalence. If left untreated, the deformity has severely disabling effects on mobility and quality of life. Given its prevalence and significance, numerous studies are published on this condition every year. In this article, we attempt to highlight important themes and findings of studies published on idiopathic clubfoot over the past 3 years.

Background Iatrogenic injection injury is a major cause of disability in Ugandan children. Two injuries thought to result from injection of medications into the gluteal region include post-injection paralysis (PIP) and gluteal fibrosis (GF). This study aimed to describe perceptions of local health care workers regarding risk factors, particularly injections, for development of GF and PIP. Specifically, we examine the role of injection practices in the development of these injuries by interviewing a diverse cohort of individuals working in the health sector. Methods We conducted a qualitative study in the Kumi and Wakiso Districts of Uganda in November 2017, utilizing 68 key informant interviews with individuals working in healthcare related fields. Interviews were structured utilizing a moderator guide focusing on injection practices, gluteal fibrosis and post-injection paralysis. Results We identified six themes regarding perceptions of the cause of GF and PIP and organized these themes into a theoretical framework. There was a consensus among the individuals working in healthcare that inadequacies of the health care delivery system may lead to inappropriate intramuscular injection practices, which are presumed to contribute to the development of GF and PIP. Poor access to medications and qualified personnel has led to the proliferation of private clinics, which are often staffed by under-trained practitioners. Misaligned economic incentives and a lack of training may also motivate practitioners to administer frequent intramuscular injections, which cost more than oral medications. A lack of regulatory enforcement enables these practices to persist. However, due to limited community awareness, patients often perceive these practitioners as appropriately trained, and the patients frequently prefer injections over alternative treatment modalities. Conclusion This qualitative study suggests that inappropriate intramuscular injections, may arise from problems in the health care delivery system. To prevent the disability of GF and PIP, it is important to not only address the intramuscular injections practices in Uganda, but also to examine upstream deficits in access, education, and policy enforcement.

After the development of a BoGEMMS (Bologna Geant4 Multi-Mission Simulator) template for the back- ground study of X-ray telescopes, a new extension is built for the simulation of a Gamma-ray space mission (e.g. AGILE, Fermi), conceived to work as a common, multi-purpose framework for the present and future electron tracking gamma-ray space telescopes. The Gamma-ray extension involves the Geant4 mass model, the physics list and, more important, the production and treatment of the simulation output. From the user point of view, the simulation set-up follows a tree structure, with the main level being the selection of the simulation framework (the general, X-ray or gamma-ray application) and the secondary levels being the detailed configuration of the geometry and the output format. The BoGEMMS application to Gamma-ray missions has been used to evaluate the instrument performances of a new generation of Gamma-ray tele- scopes (e.g. Gamma-Light), and a full simulation of the AGILE mission is currently under construction, to scientifically validate and calibrate the simulator with real in-space data sets. A complete description of the BoGEMMS Gamma-ray framework is presented here, with an overview of the achieved results for the potential application to present and future experiments (e.g., GAMMA-400 and Gamma-Light). The evaluation of the photon conversion efficiency to beta particle pairs and the comparison to tabulated data allows the preliminary physical validation of the overall architecture. The Gamma-ray module application for the study of the Gamma-Light instrument performances is reported as reference test case.

During its first 2 years of operation, the gamma-ray AGILE satellite almost completed a full study of the gamma-ray sky. This paper presents the preliminary results of the systematic study performed on the AGILE data to search for GeV counterparts and to derive flux upper limits of the TeV sources detected by various instruments (MAGIC, HESS, VERITAS, Cangaroo, MILAGRO, ARGO, … .).

Since its early phases of operation, the AGILE mission is successfully observing Gamma Ray Bursts (GRBs) in the hard X-ray band with the SuperAGILE imager and in the MeV range with the Mini-Calorimeter. Up to now, three firm GRB detections were obtained above 25 MeV and some bursts were detected with lower statistical confidence in the same energy band. When a GRB is localized, either by SuperAGILE or Swift/BAT or INTEGRAL/IBIS or Fermi/GBM or IPN, inside the field of view of the Gamma Ray Imager of AGILE, a detection is searched for in the gamma ray band or an upper limit is provided. A promising result of AGILE is the detection of very short gamma ray transients, a few ms in duration and possibly identified with Terrestrial Gamma-ray Flashes. In this paper we show the current status of the observation of Gamma Ray Bursts and Terrestrial Gamma-ray Flashes with AGILE., Four pages and four figures

Background: The purpose of this study was to estimate the prevalence of postinjection paralysis (PIP) and gluteal fibrosis (GF) among children treated in a rural Ugandan Hospital. Methods: We conducted a retrospective cohort study by reviewing the musculoskeletal clinic and community outreach logs for children (age

AGILE is a mission of the Italian Space Agency (ASI) Scientific Program dedicated to gamma-ray astrophysics, operating in a low Earth orbit since April 23, 2007. It is designed to be a very light and compact instrument, capable of simultaneously detecting and imaging photons in the 18 keV to 60 keV X-ray energy band and in the 30 MeV{50 GeV gamma-ray energy with a good angular resolution (< 1 deg at 1 GeV). The core of the instrument is the Silicon Tracker complemented with a CsI calorimeter and a AntiCoincidence system forming the Gamma Ray Imaging Detector (GRID). Before launch, the GRID needed on-ground calibration with a tagged gamma-ray beam to estimate its performance and validate the Monte Carlo simulation. The GRID was calibrated using a tagged gamma-ray beam with energy up to 500 MeV at the Beam Test Facilities at the INFN Laboratori Nazionali di Frascati. These data are used to validate a GEANT3 based simulation by comparing the data and the Monte Carlo simulation by measuring the angular and energy resolutions. The GRID angular and energy resolutions obtained using the beam agree well with the Monte Carlo simulation. Therefore the simulation can be used to simulate the same performance on-light with high reliability., 19 page 12 figures

During the month of 2009 December, the blazar 3C 454.3 became the brightest gamma-ray source in the sky, reaching a peak flux F 2000 × 10 -8 photons cm-2 s-1 for E > 100 MeV. Starting in 2009 November intensive multifrequency campaigns monitored the 3C 454 gamma-ray outburst. Here, we report on the results of a two-month campaign involving AGILE, INTEGRAL, Swift/XRT, Swift/BAT, and Rossi XTE for the high-energy observations and Swift/UVOT, KANATA, Goddard Robotic Telescope, and REM for the near-IR/optical/UV data. GASP/WEBT provided radio and additional optical data. We detected a long-term active emission phase lasting 1 month at all wavelengths: in the gamma-ray band, peak emission was reached on 2009 December 2-3. Remarkably, this gamma-ray super-flare was not accompanied by correspondingly intense emission in the optical/UV band that reached a level substantially lower than the previous observations in 2007-2008. The lack of strong simultaneous optical brightening during the super-flare and the determination of the broadband spectral evolution severely constrain the theoretical modeling. We find that the pre- and post-flare broadband behavior can be explained by a one-zone model involving synchrotron self-Compton plus external Compton emission from an accretion disk and a broad-line region. However, the spectra of the 2009 December 2-3 super-flare and of the secondary peak emission on 2009 December 9 cannot be satisfactorily modeled by a simple one-zone model. An additional particle component is most likely active during these states. © 2010. The American Astronomical Society. All rights reserved.

Objectives: To investigate the two-year functional outcomes and complications following operative versus non-operative treatment of completely displaced midshaft clavicle fractures in adolescents. Methods: All patients 10-18 years-old treated for a midshaft clavicle fracture between August, 2013 and August, 2018 at one of 8 geographically diverse, high-volume, tertiary-care pediatric centers were enrolled, with independent treatment decisions determined by individual providers. The sub-population of patients with completely displaced fractures was prospectively followed for over 2 years. Clinical course, complications, validated patient-reported outcome measures (PROs), quality of life metrics, and satisfaction scores were analyzed. To address the ceiling effect of the PRO/satisfaction data following clavicle injuries, a priori thresholds for ‘suboptimal’ scores were established (ASES scores 10, EQ-5D Results: Of the 909 patients enrolled in the prospective study, 417 patients (45.9%) demonstrated completely displaced fractures and maintained enrollment over the study period, 277 (66%) of whom had reached two year follow up, and 151 of whom provided adequate PRO data, representing a 55% response rate. Of these patients, 55 (36%) underwent operative treatment, while 96 (64%) were treated non-operatively. Those treated surgically showed no difference in gender distribution (76% males,p=0.43), athletic participation (p=0.76), or fracture pattern (p=0.18), but were older (mean age 15.3 vs. 13.5 years, pConclusion: At eight large pediatric centers with many surgeons making independent treatment decisions, non-operative treatment of adolescent clavicle fractures demonstrated lower complication rates and similar satisfaction and functional outcomes.These data establish a comprehensive functional assessment of adolescents treated for clavicle fractures, which represents the epidemiological sub-population most affected by this condition. Unlike several adult studies demonstrating superiority in operative treatment, this adolescent study demonstrates equivalent function and fewer complications associated with non-operative treatment. [Table: see text]

The AGILE satellite has been proven to be an excellent tool to study transient gamma-ray sources since it entered in a spinning operational mode in 2009. Thanks to its scanning capabilities it observes the whole sky every few hours. Several new interesting systems were discovered, such as AGL J2241+4454 in 2010, probably associated to the mysterious black-hole high-mass X-ray binary MWC 656. With a state of the art PSF and sensitivity in the 100 MeV – 1 GeV energy range, AGILE studied this system in order to identify new periods of gamma-ray activity that could be associated to the binary, and found a total of 10 flares spanning from 2008 until 2013. AGILE studied also the Cygnus region, finding evidence of a new recent gamma-ray flare from the microquasar Cygnus X-3, with a flux of ∼ 2×10−8 ph cm−2 s, during a state transition phase in the bright high-soft X-ray state. Also Cygnus X-1 was detected in the past by AGILE, although both systems are very different and show different behaviour.

The e-ASTROGAM is a gamma-ray space mission to be proposed as the M5 Medium-size mission of the European Space Agency. It is dedicated to the observation of the Universe with unprecedented sensitivity in the energy range 0.2 - 100 MeV, extending up to GeV energies, together with a groundbreaking polarization capability. It is designed to substantially improve the COMPTEL and Fermi sensitivities in the MeV-GeV energy range and to open new windows of opportunity for astrophysical and fundamental physics space research. e-ASTROGAM will operate as an open astronomical observatory, with a core science focused on (1) the activity from extreme particle accelerators, including gamma-ray bursts and active galactic nuclei and the link of jet astrophysics to the new astronomy of gravitational waves, neutrinos, ultra-high energy cosmic rays, (2) the high-energy mysteries of the Galactic center and inner Galaxy, including the activity of the supermassive black hole, the Fermi Bubbles, the origin of the Galactic positrons, and the search for dark matter signatures in a new energy window; (3) nucleosynthesis and chemical evolution, including the life cycle of elements produced by supernovae in the Milky Way and the Local Group of galaxies. e-ASTROGAM will be ideal for the study of high-energy sources in general, including pulsars and pulsar wind nebulae, accreting neutron stars and black holes, novae, supernova remnants, and magnetars. And it will also provide important contributions to solar and terrestrial physics. The e-ASTROGAM telescope is optimized for the simultaneous detection of Compton and pair-producing gamma-ray events over a large spectral band. It is based on a very high technology readiness level for all subsystems and includes many innovative features for the detectors and associated electronics., 11 pages, 5 figures, published in the proceedings of SPIE Astronomical Telescopes and Instrumentation: Ultraviolet to Gamma Ray conference, Edinburgh 2016. Addition of an acknowledgment statement in version 2

Revegetation assessment on different areas of methane pipeline in Tuscany. Degraded areas due to extra-agricultural activity (such as quarries, dumps, ski runs, methane tracks, etc.) or to natural events (such as landslides) are present in a wide part of Italian territory and for this reason is extremely necessary an effective restoration in order to reduce erosion risks and to permit their better integration in the surrounding landscape. Revegetation is usually performed using commercial mixtures constituted by species with a forage aptitude. The aim of this work was to analyse the evolution of revegetation performed on different areas of methane pipeline in Tuscany (central Italy), both in Mediterranean environments and in mountain areas. Knowledge of mixture used during revegetation and time of intervention allowed, on one hand, to discriminate species introduced by revegetation from those coming out from native recolonisation of tracks, on the other hand, to know the age of canopies at time of botanical analysis. The following variables were assessed on the studied herbaceous resources: ground cover, floristic composition, biodiversity, level of recolonization by native species, similarity with natural areas. Data collection permitted the evaluation of efficiency of studied revegetation, the awareness of the role played by sown and native species, the estimation of the level of native species in order to integrate the restoration with the environment and the analysis of most important parameters that affect vegetal evolution in these peculiar settings.

In 2008 AGILE and Fermi detected gamma-ray flaring activity from the unidentified EGRET source 3EG J1236+0457, recently associated with a flat spectrum radio quasar GB6 J1239+0443 at z=1.762. The optical counterpart of the gamma-ray source underwent a flux enhancement of a factor 15-30 in 6 years, and of ~10 in six months. We interpret this flare-up in terms of a transition from an accretion-disk dominated emission to a synchrotron-jet dominated one. We analysed a Sloan Digital Sky Survey (SDSS) archival optical spectrum taken during a period of low radio and optical activity of the source. We estimated the mass of the central black hole using the width of the CIV emission line. In our work, we have also investigated SDSS archival optical photometric data and UV GALEX observations to estimate the thermal-disk emission contribution of GB6 J1239+0443. Our analysis of the gamma-ray data taken during the flaring episodes indicates a flat gamma-ray spectrum, with an extension of up to 15 GeV, with no statistically-relevant sign of absorption from the broad line region, suggesting that the blazar-zone is located beyond the broad line region. This result is confirmed by the modeling of the broad-band spectral energy distribution (well constrained by the available multiwavelength data) of the flaring activity periods and by the accretion disk luminosity and black hole mass estimated by us using archival data.

At the core of the AGILE scientific instrument, designed to operate on a satellite, there is the Gamma Ray Imaging Detector (GRID) consisting of a Silicon Tracker (ST), a Cesium Iodide Mini-Calorimeter and an Anti-Coincidence system of plastic scintillator bars. The ST needs an on-ground calibration with a g-ray beam to validate the simulation used to calculate the energy response function and the effective area versus the energy and the direction of the g rays. A tagged g-ray beam line was designed at the Beam Test Facility (BTF) of the INFN Laboratori Nazionali of Frascati (LNF), based on an electron beam generating g-rays through bremsstrahlung in a position-sensitive target. The g-ray energy is deduced by difference with the post-bremsstrahlung electron energy [1,2]. The electron energy is measured by a spectrometer consisting of a dipole magnet and an array of position sensitive silicon strip detectors, the Photon Tagging System (PTS). The use of the combined BTF-PTS system as tagged photon beam requires understanding the efficiency of g-ray tagging, the probability of fake tagging, the energy resolution and Contents lists available at SciVerse ScienceDirect

The present investigation was carried out in Val Visdende (north-eastern Italian Alps) on a surface of 1108 ha, with the aim of identifying the most important pasture vegetation types. Based on the conditions observed in the area, main parameters concerning topographic, ecological and management conditions were evaluated and expressed using synthetic indexes. Cluster and principal component analyses were used for the interpretation of the distribution of pasture types in relation to ecological factors, allowing to formulate hypotheses on the evolution of pasture vegetation as a function of ecological and management parameters.

The Arecibo Galaxy Environment Survey is a blind neutral hydrogen survey using the ALFA multibeam receiver at Arecibo Observatory to reach unprecedented sensitivities in a number of selected fields in the local Universe. When completed the survey will cover 200 square degrees out to a distance of at least 270 Mpc. If a population of gas-rich dark galaxies exists, then this survey is in a prime position to uncover that population.So far 20 square degrees have been covered in the regions of Abell 1367, the Virgo Cluster, the NGC 7332/9 galaxy pair and the isolated galaxy NGC 1156. Over 200 sources have been found, including a number that have no obvious optical counterparts. We discuss here the potential of AGES for uncovering more such objects and the characteristics of the dark sources identified to date.

We outline an approach devoted to the detection of low surface brightness galaxies on astronomical images. We use a multi-scale approach, take into account sources of incompleteness and check selection functions both analytically and with simulations.

The nature of the dwarf galaxy population as a function of location in the cluster and within different environments is investigated. We have previously described the results of a search for low surface brightness objects in data drawn from an East-West strip of the Virgo cluster (Sabatini et al., 2003) and have compared this to a large area strip outside of the cluster (Roberts et al., 2004). In this talk I compare the East-West data (sampling sub-cluster A and outward) to new data along a North-South cluster strip that samples a different region (part of sub-cluster A, and the N,M clouds) and with data obtained for the Ursa Major cluster and fields around the spiral galaxy M101. The sample of dwarf galaxies in different environments is obtained from uniform datasets that reach central surface brightness values of ~26 B mag/arcsec^2 and an apparent B magnitude of 21 (M_B=-10 for a Virgo Cluster distance of 16 Mpc). We discuss and interpret our results on the properties and distribution of dwarf low surface brightness galaxies in the context of variuos physical processes that are thought to act on galaxies as they form and evolve., 10 pages, 3 figures, to appear in "Dark Galaxies and Lost Baryons", IAU244 conference proceedings

The universal link between the processes of accretion and ejection leads to the formation of jets and outflows around accreting compact objects. Incoherent s ynchrotron emission from these outflows can be observed from a wide range of accreting binaries, including black holes, neutron stars, and white dwarfs. Monitoring the evolution of the radio emission during their sporadic outbursts provides important insights into the launching o f jets, and, when coupled with the behaviour of the source at shorter wavelengths, probes the underlying connection with the accretion process. Radio observations can also probe the impact of jets/outflows (including other explosive events such as magnetar giant flares) on the ambient medium, q uantifying their kinetic feedback. The high sensitivity of the SKA will open up new parameter space, enabling the monitoring of accreting stellar-mass compact objects from their bright, Eddington-limited outburst states down to the lowest-luminosity quiescent levels, whose intrinsic faintness has to date precluded detailed studies. A census of quiescently accreting black h oles will also constrain binary evolution processes. By enabling us to extend our existing investigations of black hole jets to the fainter jets from neutron star and white dwarf systems, the SKA will permit comparative studies to determine the role of the compact object in jet formation. The high sensitivity, wide field of view and multibeaming capability of the SKA will enable the detection and monitoring of all bright flaring transients in the observable local Universe (within ∼ 15 Mpc), including the radio counterparts of ultraluminous X-ray sources, improving our understanding of accretion and jet ejection at the highest rates, with important implications for the growth of the first quasars. As synchrotron events peak earlier at higher frequencies, and with higher flux densities, such studies will be best enabled by SKA1-MID, in the higher-frequency bands 4 and 5. With the high sensitivity available from SKA1-MID, we will also be able to probe isolated quiescent black holes undergoing Bondi-Hoyle accretion from the nearby environment, both stellar-mass black holes in the field and the putative population of intermediat e black holes in globular clusters. This chapter reviews the science goals outlined above, demonstrating the progress that will be made by the SKA in studying incoherent synchrotron emission from accreting compact objects. We also discuss the potential of the astrometric and imaging observations that would be possible should a significant VLBI component be included in phase 1 (and eventu ally phase 2) of the SKA.

We present the results of multi-year gamma-ray observations by the AGILE satellite of the black hole binary system Cygnus X-1. In a previous investigation we focused on gamma-ray observations of Cygnus X-1 in the hard state during the period mid-2007/2009. Here we present the results of the gamma-ray monitoring of Cygnus X-1 during the period 2010/mid-2012 carried out for which includes a remarkably prolonged `soft state' phase (June 2010 -- May 2011). Previous 1--10 MeV observations of Cyg X-1 in this state hinted at a possible existence of a non-thermal particle component with substantial modifications of the Comptonized emission from the inner accretion disk. Our AGILE data, averaged over the mid-2010/mid-2011 soft state of Cygnus X-1, provide a significant upper limit for gamma-ray emission above 100 MeV of F_soft < 20 x 10^{-8} ph/cm^2/s, excluding the existence of prominent non-thermal emission above 100 MeV during the soft state of Cygnus X-1. We discuss theoretical implications of our findings in the context of high-energy emission models of black hole accretion. We also discuss possible gamma-ray flares detected by AGILE. In addition to a previously reported episode observed by AGILE in October 2009 during the hard state, we report a weak but important candidate for enhanced emission which occurred at the end of June 2010 (2010-06-30 10:00 - 2010-07-02 10:00 UT) exactly in coincidence with a hard-to-soft state transition and before an anomalous radio flare. An appendix summarizes all previous high-energy observations and possible detections of Cygnus X-1 above 1 MeV., 16 pages, 12 figures, 1 table, accepted for publication in ApJ

Context: AGILE is a gamma-ray astrophysics mission which has been in orbit since 23 April 2007 and continues to operate reliably. The gamma-ray detector, AGILE-GRID, has observed Galactic and extragalactic sources, many of which were collected in the first AGILE Catalog. Aims: We present the calibration of the AGILE-GRID using in-flight data and Monte Carlo simulations, producing Instrument Response Functions (IRFs) for the effective area A_eff), Energy Dispersion Probability (EDP), and Point Spread Function (PSF), each as a function of incident direction in instrument coordinates and energy. Methods: We performed Monte Carlo simulations at different gamma-ray energies and incident angles, including background rejection filters and Kalman filter-based gamma-ray reconstruction. Long integrations of in-flight observations of the Vela, Crab and Geminga sources in broad and narrow energy bands were used to validate and improve the accuracy of the instrument response functions. Results: The weighted average PSFs as a function of spectra correspond well to the data for all sources and energy bands. Conclusions: Changes in the interpolation of the PSF from Monte Carlo data and in the procedure for construction of the energy-weighted effective areas have improved the correspondence between predicted and observed fluxes and spectra of celestial calibration sources, reducing false positives and obviating the need for post-hoc energy-dependent scaling factors. The new IRFs have been publicly available from the Agile Science Data Centre since November 25, 2011, while the changes in the analysis software will be distributed in an upcoming release.

In order to investigate the nature of dwarf Low Surface Brightness (LSB) galaxies we have undertaken a deep B and I band CCD survey of a 14 sq degree strip in the Virgo Cluster and applied a Fourier convolution technique to explore its dwarf galaxy population down to a central surface brightness of � 26 B mag/ arcsec 2 and a total absolute B mag of � -10. In this paper we carry out an analysis of their morphology, (B-I) colours and atomic hydrogen content. We compare these properties with those of dwarf galaxies in other environments to try and assess how the cluster environment has influenced their evolution. Field dwarfs are generally of a more irregular morphology, are bluer and contain relatively more gas. We assess the importance that various physical processes have on the evolution of cluster dwarf galaxies (ram pressure stripping, tidal interactions, supernova driven gas loss). We suggest that enhanced star formation triggered by tidal interactions is the major reason for the very different general properties of cluster dwarfs: they have undergone accelerated evolution.

Galaxy harassment has been proposed as a physical process that morphologically transforms low surface density disc galaxies into dwarf elliptical galaxies in clusters. It has been used to link the observed very different morphology of distant cluster galaxies (relatively more blue galaxies with 'disturbed' morphologies) with the relatively large numbers of dwarf elliptical galaxies found in nearby clusters. One prediction of the harassment model is that the remnant galaxies should lie on low surface brightness tidal streams or arcs. We demonstrate in this paper that we have an analysis method that is sensitive to the detection of arcs down to a surface brightness of 29 B mag/arcsec^2 and then use this method to search for arcs around 46 Virgo cluster dwarf elliptical galaxies. We find no evidence for tidal streams or arcs and consequently no evidence for galaxy harassment as a viable explanation for the relatively large numbers of dwarf galaxies found in the Virgo cluster., Accepted for publication in MNRAS

Context. The detection and the characterization of the high energy emission component from individual gamma-ray bursts (GRBs) is one of the key science objectives of the currently operating gamma-ray satellite AGILE, launched in April 2007. In its first two years of operation AGILE detected three GRBs with photons of energy larger than 30 MeV. One more GRB was detected in AGILE third operation year, while operating in spinning mode. Aims. For the 64 other GRBs localized during the period July 2007 to October 2009 in the field of view of the AGILE Gamma-Ray Imaging Detector (GRID), but not detected by this instrument, we estimate the count and flux upper limits on the GRB high energy emission in the AGILE-GRID energy band (30 MeV-3 GeV). Methods. To calculate the count upper limits, we adopted a Bayesian approach. The flux upper limits are derived using several assumptions on the high-energy spectral behavior. For 28 GRBs with available prompt spectral information, a flux upper limit and the comparison with the expected flux estimated from spectral extrapolation of the Band spectrum to the 30 MeV-3 GeV band are provided. Moreover, upper limits on the flux under the assumption of an extra power law component dominating the 30 MeV-3 GeV band are calculated for all GRBs and considering four different values for the spectral photon index. Finally, we performed a likelihood upper limit on the possible delayed emission up to 1 h after the GRB. Results. The estimated flux upper limits range between 1 x 10(-4) and similar to 2 x 10(-2) photons cm(-2) s(-1) and generally lie above the flux estimated from the extrapolation of the prompt emission in the 30 MeV-3 GeV band. A notable case is GRB 080721, where the AGILE-GRID upper limit suggests a steeper spectral index or the presence of a cut-off in the high energy part of the Band prompt spectrum. The four GRBs detected by AGILE-GRID show high-energy (30 MeV-3 GeV) to low-energy (1 keV-10 MeV) fluence ratios similar to those estimated in this paper for the 64 GRBs without GRID detection, favoring the possibility that AGILE-GRID detected only high-fluence, hard GRBs. From the flux upper limits derived in this work we put some constraint on high-energy radiation from the afterglow emission and from synchrotron self Compton emission in internal shocks.

During its first 2 years of operation, the gamma-ray AGILE satellite accumulated an extensive dataset for the Galactic plane. The data have been monitored for transient sources and several gamma-ray sources were detected. Their variability and possible association were studied. In this talk we will focus on the results of extensive observations of the Carina Region during the time period 2007 July - 2009 January, for a total livetime of ~130 days. The region is extremely complex, hosting massive star formation, with the remarkable colliding wind binary Eta Carinae, massive star clusters and HII regions (e.g. NGC 3324, RCW49, Westerlund II) and a giant molecular cloud extending over 150 pc (between l=284.7 and l=289). The Carina Nebula itself is the largest and IR highest surface brightness nebula of the Southern emisphere. We monitored several gamma ray sources in the Carina Region. In particular we detect a gamma ray source (1AGL J1043-5931) consistent with the position of Eta Carinae and report a remarkable 2-days gamma-ray flaring episode from this source on 2008 Oct 11-13. If 1AGL J1043-5931 is associated with the Eta Car system, our data provides the long sought first detection above 100 MeV of a colliding wind binary., 5 pages, 5 figures, proceedings of RICAP 2009

At the core of the AGILE scientific instrument, designed to operate on a satellite, there is the Gamma Ray Imaging Detector (GRID) consisting of a Silicon Tracker (ST), a Cesium Iodide Mini-Calorimeter and an Anti-Coincidence system of plastic scintillator bars. The ST needs an on-ground calibration with a γ-ray beam to validate the simulation used to calculate the energy response function and the effective area versus the energy and the direction of the γ rays. A tagged γ-ray beam line was designed at the Beam Test Facility (BTF) of the INFN Laboratori Nazionali of Frascati (LNF), based on an electron beam generating γ rays through bremsstrahlung in a position-sensitive target. The γ-ray energy is deduced by the difference with the post-bremsstrahlung electron energy 1-.2 The electron energy is measured by a spectrometer consisting of a dipole magnet and an array of position sensitive silicon strip detectors, the Photon Tagging System (PTS). The use of the combined BTF-PTS system as tagged photon beam requires understanding the efficiency of γ-ray tagging, the probability of fake tagging, the energy resolution and the relation of the PTS hit position versus the γ-ray energy. This paper describes this study comparing data taken during the AGILE calibration occurred in 2005 with simulation.

We present the AGILE-GRID monitoring of Cygnus X-3, during the period between November 2007 and July 2009. We report here the whole AGILE-GRID monitoring of Cygnus X-3 in the AGILE "pointing" mode data-taking, to confirm that the gamma-ray activity coincides with the same repetitive pattern of multiwavelength emission and to analyze in depth the overall gamma-ray spectrum by assuming both leptonic and hadronic scenarios. Seven intense gamma-ray events were detected in this period, with a typical event lasting one or two days. These durations are longer than the likely cooling times of the gamma-ray emitting particles, implying we see continuous acceleration rather than the result of an impulsive event such as the ejection of a single plasmoid which then cools as it propagates outwards. Cross-correlating the AGILE-GRID light curve with X-ray and radio monitoring data, we find that the main events of gamma-ray activity have been detected while the system was in soft spectral X-ray states (RXTE/ASM count rate > 3 counts/s), that coincide with local and often sharp minima of the hard X-ray flux (Swift/BAT count rate < 0.02 counts/cm^2/s), a few days before intense radio outbursts. [...] These gamma-ray events may thus reflect a sharp transition in the structure of the accretion disk and its corona, which leads to a rebirth of the microquasar jet and subsequent enhanced radio activity. [...] Finally, we examine leptonic and hadronic emission models for the gamma-ray events and find that both scenarios are valid. In the leptonic model - based on inverse Compton scatterings of mildly relativistic electrons on soft photons from the Wolf-Rayet companion star and from the accretion disk - the emitting particles may also contribute to the overall hard X-ray spectrum, possibly explaining the hard non-thermal power-law tail sometimes seen during special soft X-ray states in Cygnus X-3., Accepted for publication in A&A on July 26, 2012