1,721,196 research outputs found
The Upsides of Turbulence: Baselining Gossip Learning in Dynamic Settings
No full textIn dynamic settings, fully distributed gossip-based learning schemes have recently gained interest due to their better scalability, robustness, and enhanced privacy protection compared to server-based architectures. However, existing approaches to their performance characterization either assume stable connectivity among nodes or are ad-hoc for specific trace-based mobility patterns. Thus, in dynamic settings, there is currently a poor understanding of the conditions under which gossip-based learning schemes are feasible, and of their main performance tradeoffs. In this work, we start addressing this issue by performing a first baselining of Gossip Learning (GL) on random Time-Varying Graphs (TVG), to get a first-order characterization of their main performance patterns in dynamic settings. The use of random TVG enables a fine-grained and accurate characterization of GL effectiveness as a function of the main system parameters while abstracting from scenariospecific features of patterns of communication and mobility (e.g., induced by road grids or measured mobility traces). Our results suggest that GL schemes are robust to node mobility and comparable in accuracy and convergence speed to Federated Learning architectures, over a wide range of operational conditions. We show that the final model accuracy is robust against data dispersion across nodes as well as against very low rates of exchanges across nodes
Help From Above: UAV-Empowered Network Resiliency in Post-Disaster Scenarios
No full textNatural and man-made disasters have often consequences on service availability in a wireless access network, provoking a progressively degraded performance or even the lack of connectivity. However, given the growing importance of situation awareness, telehealth, and advanced rescue teams coordination services for the affected population, it is key to restore these services in a timely fashion, while guaranteeing the required QoS levels. To this end, UAV-mounted base stations have been recently proposed as a key instrument to achieve this goal. Nonetheless, this gives rise to the key issue of how to deploy them in a resource efficient manner, in a post-disaster context typically characterized by lack of infrastructure support and of power supply. In this work, we tackle the issue of how to jointly optimize drones deployment and user association in a QOS aware manner to efficiently cater for coverage holes and QoS degradation in a cellular network after a disaster. We formulate a network optimization problem, and we provide a two-step genetic algorithm which iteratively tunes UAV position, base station transmit power and user association in order to minimize the number of employed drones. Initial results on a realistic measurement based scenario show that our approach is able to effectively minimize the number of deployed drones while achieving a target minimum QoS
The Debated Issue on Tissue Copper Levels in Colorectal Cancer Patients: A Meta-analysis and Replication Study
No full textColorectal cancer (CRC) is a growing public health problem. Several clinical studies have shown a potentially oncogenic role of copper in CRC progression, but the reports are inconsistent. To examine published evidence on the association between tissue copper status and CRC, we carried out a systematic review and meta-analysis, searching Cochrane Library, EBSCOhost, Embase, ProQuest, PubMed/Medline, Scopus, and Web of Science for studies reporting colon tumor and matched non-cancerous tissue copper concentrations in CRC patients for articles published till June 2023. Based on a random effects model, standardized mean differences (SMD) were assessed. We also completed a replication study on 17 CRC patients that analyzed copper levels in both cancer tissue specimens and healthy mucosa dissected from the same patient. Thirteen studies investigating copper levels (including the replication study) in colorectal specimens from a pooled total of 312 CRC and 298 healthy mucosa were selected. Our meta-analysis estimated a high between-study heterogeneity (I2 = 96%) and lower levels of copper in CRC tissue cancer specimens than in matched healthy mucosa: the decrease was equal to − 0.74 (95% CI, − 2.18; 0.71) but was not significant. The replication study showed a significant decrease in tissue cancer specimens. Sensitivity analyses of the meta-analysis revealed that pre-analytical methodology for tissue preparation significantly reduced the between-study heterogeneity strongly influencing copper levels (p < 0.01), indicating a copper decrease in the cytoplasmic copper pool of the tumor tissue suggesting a rapid turnover of the metal in cancer cells
Energy-optimal RAN configurations for SWIPT IoT
No full textInternet of Things (IoT) devices often have batteries of limited capacity, which are not easily replaced or recharged. This implies very short device lifetimes, and calls for a very careful device configuration to achieve the optimal trade-off between performance and power consumption. SWIPT (Simultaneous Wireless Information and Power Transfer) deals with this problem by harvesting energy at IoT devices from the received RF signals. Studying the efficiency of SWIPT in dealing with the energy and data transfer demands of IoT nodes leads to a number of open issues. In this paper, we devise an analytical model based on stochastic geometry for a SWIPT radio access network with a dense population of IoT users. With our model, it is possible to accurately study the impact of the system parameters on the key system performance indicators, while accounting in a realistic manner for device performance, and for the statistics of time scheduling at base stations. This allows us to understand (not without some surprise) what are the most effective strategies to minimize energy consumption in a SWIPT network, and what is their potential for energy savings
Surgical treatment of small bowel neoplasms.
No full textSmall intestinal neoplasms are uncommon cancers. Benign small intestinal tumors (e.g., leiomyoma, lipoma, hamartoma, or desmoid tumor) usually are asymptomatic but may present with complications. Primary malignancies of the small intestine, including adenocarcinoma, leiomyosarcoma, carcinoid, and lymphoma, are often symptomatic and may present with intestinal obstruction, jaundice, bleeding, or pain. Metastatic neoplasms may involve the small intestine via contiguous spread, peritoneal metastases or hematogenous metastases. Because the small intestine is relatively inaccessible to routine endoscopy, diagnosis of small intestinal neoplasms is often delayed for months after onset of symptoms. During last years the increase of small bowel endoscopy and other diagnostic tools allow earlier non-operative diagnosis. Even though radical resection of small bowel cancer plays an important role, the 5 yr overall survival remains low
Anti-TNF-alpha therapies do not increase early postoperative complications in patients with inflammatory bowel disease. An Italian single-center experience.
No full textPURPOSE:
The impact of preoperative use of TNF-alpha inhibitors on postoperative complications in patients with inflammatory bowel disease (IBD) undergoing abdominal surgery is controversial. The aim of this study was to evaluate the 30-day postoperative outcomes for IBD patients treated with these drugs prior to surgery.
METHODS:
We analyzed retrospectively the incidence of short-term postoperative complications. Statistical analyses were performed to reveal the independent variables that influenced postoperative complications and the role of preoperative medical therapy with anti-TNF drugs within 12 weeks prior to surgery.
RESULTS:
One hundred fourteen patients (76 with Crohn's disease (CD) and 38 ulcerative colitis (UC)) underwent abdominal surgery for IBD. Fifty-four patients were treated with anti-TNF-alpha within 12 weeks prior to surgery (anti-TNF group). Postoperative mortality and morbidity were 0% and 21%, respectively. The infection rate was 15%. A significantly higher incidence of postoperative complications was found in patients treated with high-dose steroids (58% vs. 17%; p = 0.003) after univariate analysis. The infection rate was significantly higher in patients treated with high-dose corticosteroids (50% vs. 11%; p = 0.002) and concomitant anti-TNF-alpha (60% vs. 13%; p = 0.023). Multivariate analysis revealed that only therapy with high-dose corticosteroids was significantly associated with cumulative (p = 0.017) and infective postoperative complications (p = 0.046). No significant differences were found between the anti-TNF group and the control group.
CONCLUSION:
High-dose corticosteroids increased the risk of short-term postoperative cumulative and infective complications. Anti-TNF drugs within 12 weeks prior to abdominal surgery in patients with IBD did not appear to increase the rate of postoperative complications
Mobile Networks on the Move: Optimizing Moving Base Stations Dynamics in Urban Scenarios
No full textBase station densification is one of the key approaches for delivering high capacity in radio access networks. However, current static deployments are often impractical and financially unsustainable, as they increase both capital and operational expenditures of the network. An alternative paradigm is the moving base stations (MBSs) approach, by which part of base stations are installed on vehicles. However, to the best of our knowledge, it is still unclear if and up to which point MBSs allow decreasing the number of static base stations (BSs) deployed in urban settings. In this work, we start tackling this issue by proposing a modeling approach for a first-order evaluation of potential infrastructure savings enabled by the MBSs paradigm. Starting from a set of stochastic geometry results, and a traffic demand profile over time, we formulate an optimization problem for the derivation of the optimal combination of moving and static BSs which minimizes the overall amount of BSs deployed, while guaranteeing a target mean QoS for users. Initial results on a two-district scenario with measurement-based network traffic profiles suggest that substantial infrastructure savings are achievable. We show that these results are robust against different values of user density
Vegetarian diets during pregnancy: effects on the mother's health. A systematic review
No full textWhile interest in vegetarian nutrition has been steadily increasing, some aspects have not yet been consistently investigated. One topic requiring evidence-based confirmation is the adoption of a vegetarian diet during pregnancy and lactation. Maternal diet is not only correlated with the fetus's and infant's health, but appears relevant for that of the mother as well. Not only is an adequate delivery of nutrients to the fetus and infant mandatory, but the increased physiological needs of the maternal body require an adequate supply of nutrients and can represent harmful stress events that may lead to well-defined pathological conditions. In this review, we aim to systematically investigate state-of-the-art of vegetarian diets during pregnancy and lactation, focusing on maternal nutritional status and pregnancy outcomes. Data are scarce, often inconsistent and not homogeneous for many of the topics we considered, mainly because only a few studies have been performed in developed countries, whereas other studies have derived from developing countries, where vegetarianism can be a proxy indicator of malnutrition. For this reason, we did not find sufficient data to provide evidence-based information and recommendations. To date, the available literature does not clearly support a negative impact on the mother's health and pregnancy outcomes, but, analogously with the findings in the vegetarian adult population, an improvement in the quality of studies might facilitate finding more information on the possible positive impact of well-planned vegetarian diets during pregnancy and lactation. More epidemiological and interventional studies are warranted, in order to address the question as to whether vegetarian nutrition represents an advantage for the mother or poses nutritional issues that need further attention
Anti-TNF alpha in the treatment of ulcerative colitis: a valid approach for organ-sparing or an expensive option to delay surgery?
No full textUlcerative colitis (UC) is an inflammatory bowel disease affecting large bowel with variable clinical course. The history of disease has been modified by the introduction of biologic therapy, in particular Infliximab (IFX), that has demonstrated efficacy in inducing fast symptoms remission, promoting mucosal healing and maintaining long-term remission. However, surgery is still needed for UC patients: in case of failure of medical therapy and if acute complications or a malignancy occurred. Surgical treatment is associated with a short-term post-operative mortality and morbidity respectively of 0%-4% and 30%. In this study we systematically analyzed: the role of IFX in reducing the colectomy rate, the risk of post-operative morbidity in pre-operatively IFX-treated patients and the cost-effectiveness of IFX therapy. Four of 5 analyzed randomized controlled trials demonstrated that therapy with IFX significantly reduces the colectomy rate. Moreover, pre-operative treatment with IFX doesn't seem to increase post-operative infectious complications. By an economic point of view, the cost-effectiveness of IFX-therapy was demonstrated for UC patients suffering from moderate to severe UC in a study based on a cost estimation of the National Health Service of England and Wales. However, the argument is debated
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