3,861 research outputs found
Improvements in BepiColombo and JUICE radio science experiments with a multi-station tracking configuration for the reduction of Doppler noise
Radio science experiments for planetary geodesy mostly rely on measurements of the Doppler shift of microwave signals sent to a spacecraft by an Earth station, and retransmitted back coherently in phase to the same antenna (two-way link). The retransmitted signal can also be received by a different station in a listen-only configuration (three-way link). In state-of-the-art tracking systems, such as the ones will be used on the future ESA's missions JUICE and BepiColombo, the Doppler error budget is dominated by local noise sources arising at the ground-station, in particular tropospheric scintillation and unmodeled motions of the antenna's structure. In this work, a novel technique aimed at reducing these disturbances is analyzed, with particular emphasis on its benefits to BepiColombo's and JUICE's radio science experiments. The method, referred to as Time-Delay Mechanical-noise Cancellation (TDMC), relies on simultaneous two-way and three-way spacecraft tracking, the latter employing a stiffer listen-only antenna with better mechanical stability and located in a favorable dry region more immune to tropospheric noise. In fact, a proper linear combination of time-shifted observables from the two-way and three-way links can replace local noises of the two-way ground-station with those coming from the listen-only antenna, translating into increased accuracy of the final measurements, while preserving the original Doppler content. We show the results of covariance analyses performed with a multi-arc weighted least square estimator for the entire BepiColombo's Hermean phase and JUICE's flybys of Callisto. We compare the two solutions obtained with and without the application of the TDMC technique. For BepiColombo and JUICE radio science experiments, the two-way links are baselined from the 35-m DSA-3 (Malargüe, Argentina) and the 34-m DSS 25 (Goldstone, California). For the three-way link, we select the 12-m Large Latin American Millimeter Array (LLAMA) antenna for three reasons: 1) its mechanical rigidity with respect to large beam-waveguide antennas, 2) its unique position in the extremely dry Puna de Atacama desert, that assures low tropospheric noise, and 3) its limited longitudinal separation from the two other ground-stations, granting sufficient common visibility time to perform the requested combination of the observables. Besides its noise-reduction effect, enabling unprecedented levels of accuracy on Doppler measurements, TDMC provides also a back-up for unique events: a crucial satellite flyby or a specific passage over a site of particular geophysical interest. Indeed, measurements become virtually independent of unfavorable meteorological conditions at the transmitting station
Blocking CD248 molecules in perivascular stromal cells of patients with systemic sclerosis strongly inhibits their differentiation toward myofibroblasts and proliferation: A new potential target for antifibrotic therapy
Background: Fibrosis may be considered the hallmark of systemic sclerosis (SSc), the end stage triggered by different pathological events. Transforming growth factor-β (TGF-β) and platelet-derived growth factor BB (PDGF-BB) are profibrotic molecules modulating myofibroblast differentiation and proliferation, respectively. There is evidence linking CD248 with these two molecules, both highly expressed in patients with SSc, and suggesting that CD248 may be a therapeutic target for several diseases. The aim of this work was to evaluate the expression of CD248 in SSc skin and its ability to modulate SSc fibrotic process. Methods: After ethical approval was obtained, skin biopsies were collected from 20 patients with SSc and 10 healthy control subjects (HC). CD248 expression was investigated in the skin, as well as in bone marrow mesenchymal stem cells (MSCs) treated with TGF-β or PDGF-BB, by immunofluorescence, qRT-PCR, and Western blotting. Finally, in SSc-MSCs, the CD248 gene was silenced by siRNA. Results: Increased expression of CD248 was found in endothelial cells and perivascular stromal cells of SSc skin. In SSc-MSCs, the levels of CD248 and α-smooth muscle actin expression were significantly higher than in HC-MSCs. In both SSc- and HC-MSCs, PDGF-BB induced increased expression of Ki-67 when compared with untreated cells but was unable to modulate CD248 levels. After CD248 silencing, both TGF-β and PDGF-BB signaling were inhibited in SSc-MSCs. Conclusions: CD248 overexpression may play an important role in the fibrotic process by modulating the molecular target, leading to perivascular cells differentiation toward myofibroblasts and interfering with its expression, and thus might open a new therapeutic strategy to inhibit myofibroblast generation during SSc
Subchondroplasty in the treatment of bone marrow lesions of the knee: Preliminary experience on first 15 patients
Purpose The aim of this prospective study was to assess the effectiveness in terms of pain relief and functional improvement of the Subchondroplasty procedure in the treatment of osteoarthritis-related bone marrow lesions (BMLs) of the knee. Methods The study included first 15 consecutive patients undergone to Subchon-droplasty procedure for the treatment of chronic degenerative BMLs in which previous conservative treatment have failed. Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores, Knee Injury and Osteoarthritis Outcome Scores (KOOS), and visual analog scale (VAS) pain scores were obtained preoperatively and at 1, 6, and 12 months of follow-up. Results WOMAC scores significantly improved from 39.7 \ub1 20.2 before surgery to 26.8 \ub1 16.1 at the 1-month follow-up (p = 0.045). A further significant improvement to 15.5 \ub1 12.7 (p = 0.02) and to 8.6 \ub1 3.1 (p <0.01) was obtained both at 6-month and at 1-year follow-up. KOOS scores improved significantly from 47.5 \ub1 16.6 before surgery to 65.4 \ub1 14.9 at 1 month (p = 0.013) and to 80.4 \ub1 15.1 at 6-month follow-up (p = 0.01). A further improvement to 85.6 \ub1 15.1 was recorded 1 year postoperatively, although nonsignificant. VAS score showed a significant improvement from 55.8 \ub1 20.5 preoperatively to 36.2 \ub1 16.9 at 1 month (p = 0.008) and to 18.2 \ub1 17.3 at 6-month follow-up (p = 0.005). This further improved to 12.8 \ub1 17.9 at 1-year follow-up, although not significantly. Conclusion Subchondroplasty procedure represents a safe and valid surgical option in the treatment of osteoarthritis-related BMLs of the knee, providing an improvement in terms of pain relief and functional recovery. Longer studies are required to evaluate how long these improvements may last. Level of Evidence Therapeutic case-series, Level IV study
Issues of “Standard” explosion tests for non-spherical dusts
Measurements of the flammability and explosion parameters for non-spherical dusts are performed according to standard procedures in standard explosion equipment developed and tested for spherical dusts. Studies have shown that the standard procedures and equipment applied to spherical particles suffer from many issues: control of the turbulence level, non-uniform dust dispersion, and particle fragmentation due to the injection system. The applicability of the standard procedures and equipment to non-spherical particles is still an open issue. In this work, we have investigated, via CFD simulations, the distribution of turbulence and dust concentration in the standard 20 l spherical vessel for non-spherical particles. Results have shown that a higher turbulence level and a higher amount of dust actually fed into the vessel are reached with respect to spherical particles
Microenvironment in neuroblastoma: Isolation and characterization of tumor-derived mesenchymal stromal cells
Background: It has been proposed that mesenchymal stromal cells (MSCs) promote tumor progression by interacting with tumor cells and other stroma cells in the complex network of the tumor microenvironment. We characterized MSCs isolated and expanded from tumor tissues of pediatric patients diagnosed with neuroblastomas (NB-MSCs) to define interactions with the tumor microenvironment. Methods: Specimens were obtained from 7 pediatric patients diagnosed with neuroblastoma (NB). Morphology, immunophenotype, differentiation capacity, proliferative growth, expression of stemness and neural differentiation markers were evaluated. Moreover, the ability of cells to modulate the immune response, i.e. inhibition of phytohemagglutinin (PHA) activated peripheral blood mononuclear cells (PBMCs) and natural killer (NK) cytotoxic function, was examined. Gene expression profiles, known to be related to tumor cell stemness, Wnt pathway activation, epithelial-mesenchymal transition (EMT) and tumor metastasis were also evaluated. Healthy donor bone marrow-derived MSCs (BM-MSC) were employed as controls. Results: NB-MSCs presented the typical MSC morphology and phenotype. They showed a proliferative capacity superimposable to BM-MSCs. Stemness marker expression (Sox2, Nanog, Oct3/4) was comparable to BM-MSCs. NB-MSC in vitro osteogenic and chondrogenic differentiation was similar to BM-MSCs, but NB-MSCs lacked adipogenic differentiation capacity. NB-MSCs reached senescence phases at a median passage of P7 (range, P5-P13). NB-MSCs exhibited greater immunosuppressive capacity on activated T lymphocytes at a 1:2 (MSC: PBMC) ratio compared with BM-MSCs (p = 0.018). NK cytotoxic activity was not influenced by co-culture, either with BM-MSCs or NB-MSCs. Flow-cytometry cell cycle analysis showed that NB-MSCs had an increased number of cells in the G0-G1 phase compared to BM-MSCs. Transcriptomic profiling results indicated that NB-MSCs were enriched with EMT genes compared to BM-MSCs. Conclusions: We characterized the biological features, the immunomodulatory capacity and the gene expression profile of NB-MSCs. The NB-MSC gene expression profile and their functional properties suggest a potential role in promoting tumor escape, invasiveness and metastatic traits of NB cancer cells. A better understanding of the complex mechanisms underlying the interactions between NB cells and NB-derived MSCs should shed new light on potential novel therapeutic approaches
Total knee revision arthroplasty: comparison between tibial tubercle osteotomy and quadriceps snip approach. Complication rate
BACKGROUND AND AIM OF THE WORK: The total knee arthroplasty (TKA) revision is not a second time of primary implant surgery but is a very complex issue for orthopedic surgeon. When local conditions make necessary a greater visualization, medial para-patellar access with quadriceps snip (QS) or the osteotomy of the tibial tuberosity (TTO) can be the solutions. This work aims to compare the quadriceps snip and the detachment of the tibial tubercle, focusing on possible complications. MATERIALS AND METHODS: At our institution, between January 2017 and February 2019 52 TKA revision for periprosthetic joint infection (PJI) or aseptic mobilization were performed. In 43 cases an extensive surgical approach was required: for patients with range of movement (ROM) 60\ub0 a QS was performed. Clinical and radiological follow-up was available for all the 43 cases. RESULTS: The data about clinical outcome in our study show that both groups have a positive trend in KSS score over time with similar ROM results. Two partial avulsions of patellar tendon during revision surgery were reported. Clinical outcome in both groups has shown good results at the end of follow-up with no post-operative incidence of complications. CONCLUSION: We can assert that both QS and TTO are good approach for TKA revision. Future studies will be needed to understand if preparatory ROM is a good way to decide which surgical approach to use.(www.actabiomedica.it)
ISOLATED CAUDATE LOBECTOMY FOR SPIEGEL LOBE NEOPLASMS
Introduction: Caudate lobe, or segment 1 of the liver, is the segment of the liver that occupies the space between the hilar plate and the retrohepatic vena cava. Its peculiar embryology accounts for the unique vascular and biliary anatomy. The location among three major vascular structures (the hepato-duodenal ligament, the vena cava and the hepatic veins cranially), together with its characteristic hypertrophy in case of increased portal system pressure, makes the caudate lobe as one of the most challenging liver segments. Caudate lobe resections for tumor may be performed as isolated segmental resections or associated to major hepatic resections, when other liver segments are involved. We describe here our 14-years experience of 7 cases of isolated caudate lobe resection for tumor.Patients and Methods: From October 2000 to December 2014 826 patients underwent liver resection at our institution, of which 286 (34.6%) minor resection (wedge resection, sub-segmental resection and segmental resection), 200 (24.2%) right hepatectomy, 260 (31.4%) left hepatectomy, 20 (2.4%) left trisegmentectomy and 60 (7.2%) patient right trisegmentectomy. Of those, 45 (8.3%) had a concomitant caudate lobe resection. In seven patients (0.8%), the tumor was confined to the caudate lobe and an isolated caudate lobe resection was performed. The indication was as follow: 2 patients had Hepatocellular carcinoma (HCC), 3 patients had metastasis (colorectal in two cases and from adrenal gland in one case), 1 adenoma, and one presented with a non-Hodgkin lymphoma. For these patients we analyzed intraoperative data, post operative course and survival.Results: Five (71.4%) out of 7 patients are still alive after a mean follow up of 8.4+/-5 years. Two patients died of disease recurrence after 7 months and 8 years, respectively. The mean operating time was 304.8+/-109.7 minutes and the mean estimated blood loss was 266.6+/-123.8 ml. There were no intra-operative or post-operative complication. The mean Intensive Care Unit stay was 1.2+/-0.7 days. Each lesion was localized into the Spiegel lobe, and each patient had at the pathology specimen only one nodule. In all cases the margins were free of tumor.Conclusions: Isolated caudate lobectomy is a difficult surgical procedure that may be associated with significant intra-operative bleeding and dangerous vascular and biliary injuries. In spite of these difficulties, this procedure can be considered the gold standard treatment for any lesions, benign or malignant, involving and confined to the Spiegel Lobe, especially when is crucial to preserve the remnant parenchyma
ILCRoot Tracker and Vertex Detector Hits Response to MARS15 Simulated Backgrounds in the Muon Collider
Abstract Results from a simulation of the background for a muon collider, and the hits response of a silicon tracking detector to this backgroundare presented.The backgroundcausedbydecaysofthe750 GeV/ c beam μ + and μ − was simulated using the MARS15 program, which included the infrastructure of the beam line elements near the detector and the 10 ∘ nozzles that shield the detector from this background. The ILCRoot framework, along with the Geant4 program, was used to simulate the hits response of the tracker and vertex silicon detectors to the muon-decay background remaining after the shielding nozzles. Results include the hit distributions in these detectors, the fractions of type-specific background particles producing these hits and illustrate the use of timing of the hits to suppress the muon beam background
Determinants of influenza vaccination among solid organ transplant recipients attending Sicilian reference center
Among solid organ transplant recipients, influenza infection is commonly associated with higher morbidity and mortality than immunocompetent hosts. Therefore, in these subjects influenza vaccination is of paramount importance. The main objective of the study was to assess compliance to vaccination and analyze factors associated with influenza vaccination of solid organ transplant recipients admitted to the Sicilian solid organ transplant Reference Center IRCCS-ISMETT in Palermo during 2014\u20132015 influenza season. Thirty one (37.8%) out of 82 solid organ transplant recipients were vaccinated against influenza. The main reason for vaccination refusal was fear of adverse reaction (n = 16, 31.4%), impaired health status (n = 14, 27.4%) and low vaccine efficacy (n = 10, 19.6%). Vaccinated solid organ transplant recipients compare with unvaccinated had smaller hospital admissions for infectious respiratory diseases (9.7% Vs 23.5%) during surveillance period. On multivariate analysis the factors positively associated with influenza vaccination were the advice of Reference Center physicians (OR 53.4, p < 0.001) and to perform vaccine against pneumococcus (OR 7.0, p = 0.016). This study showed that Reference Center physicians play a key role on vaccine communication and recommendation for patients at risk and it underlines the effectiveness of influenza vaccination in solid organ transplant recipients. However, it remains that, although physician advice resulted a strong determinant for vaccination, influenza vaccination coverage in this subset of population remains still unsatisfactory
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