Abstract Statement of problem Universal adhesives combine silane and various monomers in a single bottle to make them more versatile. Their adhesive performance is unclear. Purpose The purpose of ...this in vitro study was to assess the effects of an additional silane application before using a universal adhesive on the adhesion between a disilicate glass ceramic and a composite resin by using a microshear bond strength test (μSBS) and fracture analysis immediately and after thermocycling. Material and methods One hundred lithium disilicate glass ceramic disks were divided into 10 groups for bond strength testing according to the following 3 surface treatments: silane application (built-in universal adhesive or with additional application), adhesive (Adper Single Bond Plus SB, 3M ESPE, Scotchbond Universal Adhesive U, 3M ESPE, and mixed U with Dual Cure Activator DCA, 3M ESPE); or thermocycling (half of the specimens were thermocycled 10 000 times). After surface treatment, 5 resin cylinders were bonded to each disk and submitted to a μSBS test. The failure mode was analyzed under a stereomicroscope and evaluated by scanning electron microscope and energy-dispersive x-ray spectroscopy. Data from the μSBS test were analyzed by 3-way ANOVA followed by the Tukey HSD post hoc test (α=.05). Results An additional silane application resulted in a higher μSBS result for all adhesive groups ( P <.05). Conclusions Ceramic surface treatment influenced the performance of adhesives, which may be improved with an additional silane application.
Supersingular isogeny-based cryptography is one of the more recent families of post-quantum proposals. An interesting feature is the comparatively low bandwidth occupation in key agreement protocols, ...which stems from the possibility of key compression. However, compression and decompression introduce a significant overhead to the overall processing cost despite recent progress. In this paper we address the main processing bottlenecks involved in key compression and decompression, and suggest substantial improvements for each of them. Some of our techniques may have an independent interest for other, more conventional areas of elliptic curve cryptography as well.
In machine learning, Reinforcement Learning (RL) is an important tool for creating intelligent agents that learn solely through experience. One particular subarea within the RL domain that has ...received great attention is how to define macro-actions, which are temporal abstractions composed of a sequence of primitive actions. This subarea, loosely called skill acquisition, has been under development for several years and has led to better results in a diversity of RL problems. Among the many skill acquisition approaches, graph-based methods have received considerable attention. This survey presents an overview of graph-based skill acquisition methods for RL. We cover a diversity of these approaches and discuss how they evolved throughout the years. Finally, we also discuss the current challenges and open issues in the area of graph-based skill acquisition for RL.
Classification-Based Approximate Policy Iteration Farahmand, Amir-massoud; Precup, Doina; Barreto, Andre M. S. ...
IEEE transactions on automatic control,
2015-Nov., 2015-11-00, 20151101, Letnik:
60, Številka:
11
Journal Article
Recenzirano
Tackling large approximate dynamic programming or reinforcement learning problems requires methods that can exploit regularities of the problem in hand. Most current methods are geared towards ...exploiting the regularities of either the value function or the policy. We introduce a general classification-based approximate policy iteration (CAPI) framework that can exploit regularities of both. We establish theoretical guarantees for the sample complexity of CAPI-style algorithms, which allow the policy evaluation step to be performed by a wide variety of algorithms, and can handle nonparametric representations of policies. Our bounds on the estimation error of the performance loss are tighter than existing results.
Background The aim of the study was to determine whether a vancomycin dosing algorithm based on estimated glomerular filtration rate from creatinine and cystatin C levels (eGFRcr-cys ) improves ...target trough concentration achievement compared to an algorithm based on estimated creatinine clearance (eCLcr ) in critically ill patients. Study Design This prospective quality improvement project evaluated intensive care unit (ICU) patients started on intravenous vancomycin using one of 2 different strategies. Dosing regimens were selected and implemented after an individualized goal trough range was established (10-15 or 15-20 mg/L). Steady-state goal trough achievement was compared between treatment arms with and without adjustment for potential confounders. Setting & Participants 3 medical and surgical ICUs at a single tertiary medical center. Quality Improvement Plan During January 2012 to October 2013, vancomycin was dosed according to eCLcr using the Cockcroft-Gault formula (control arm). During December 2013 to May 2015, a multidisciplinary quality improvement team implemented a novel vancomycin dosing algorithm according to eGFRcr-cys using the CKD-EPI equation (intervention arm). Outcome Steady-state initial goal vancomycin trough concentration achievement. Measurements & Results More patients in the intervention arm (67 of 135 50%) achieved therapeutic trough vancomycin levels than in the control arm (74 of 264 28%; OR, 2.53; 95% CI, 1.65-3.90; P < 0.001). Improved trough achievement was maintained even after adjustment for age, sex, APACHE (Acute Physiology and Chronic Health Evaluation) III score, fluid balance, baseline CLcr , surgical admission diagnosis, presence of sepsis, and goal trough concentration range (adjusted OR, 2.79; 95% CI, 1.76-4.44; P < 0.001). Clinical outcomes were similar between groups. Limitations Nonrandomized, incomplete algorithm compliance. Conclusions A vancomycin dosing nomogram based on eGFRcr-cys significantly improved goal trough achievement compared to eCLcr among ICU patients with stable kidney function. Further studies are warranted to characterize the relationship between use of cystatin C−guided dosing and clinical outcomes.
Cover cropping is used to improve soil quality and increase N inputs in agricultural systems, but it also may enhance greenhouse gases (GHG) emissions. Here, a 47‐d incubation study was conducted to ...track the decomposition process and evaluate GHG emissions and its drivers and to calculate the C costs of residue‐derived N released following the addition of residues from cover crops (pigeon pea, cowpea, lablab bean, vetch, and black oat) and maize under two water‐filled pore space (WFPS) levels (40 and 70%). For both WFPS levels, the increase in cumulative CO2 fluxes in plots that received residues is mainly related with the increment of potentially mineralizable C. Crop residues increased the global warming potential (GWP) under both WFPS levels, with CO2 emissions accounting for ≥98% of the GWP at 40% WFPS. At 70% WFPS, the GPW increment was driven by a notable increase in N2O emissions. The contribution of CH4 in the GWP emissions was negligible for all the crop residues evaluated. Principal component analysis highlighted that the optimal conditions for production and release are specific for each GHG. The cleaner N source was cowpea at 40% WFPS, which produced only 17.7 kg CO2‐eq kg–1 N mineralized, compared with vetch residues, which produced 233 kg CO2‐eq kg–1 N mineralized. To integrate agronomic and climate change mitigation perspectives, we suggest considering the C costs of the residue‐N released when choosing a cover crop.
Core Ideas
Cover crops alter GHG emissions, decomposition dynamics, and N balance.
Emissions associated with cover crops are plant specific and depend on soil moisture.
Crop residue addition increased the total emissions under both soil moisture levels (40 and 70%).
Optimal conditions for production and release are specific for each GHG.
The C costs of the N released from legume residues are plant specific.
Network seeding for efficient information diffusion over time-varying graphs (TVGs) is a challenging task with many real-world applications. There are several ways to model this spatio-temporal ...influence maximization problem, but the ultimate goal is to determine the best moment for a node to start the diffusion process. In this context, we propose Spatio-Temporal Influence Maximization (STIM), a model trained with Reinforcement Learning and Graph Embedding over a set of artificial TVGs that is capable of learning the temporal behavior and connectivity pattern of each node, allowing it to predict the best moment to start a diffusion through the TVG. We focus on the scenario where some nodes in the TVG present periodic connectivity patterns, an aspect that received little attention in previous approaches. We also develop a special set of artificial TVGs used for training that simulate a stochastic diffusion process in TVGs, showing that the STIM network can learn an efficient policy even over a non-deterministic environment. After trained, STIM can be used in TVGs of any size, since the number of parameters of the model is independent to the size of the TVG being processed. STIM is also evaluated in two real-world TVGs, where it also manages to efficiently propagate information through the nodes. Finally, we also show that the STIM model has a time complexity of
O
(|
E
|). STIM is also highly versatile, where one can change the goal of the model by simply changing the adopted reward function.
We present a new two-party identity-based key agreement that is more efficient than previously proposed schemes. It is inspired on a new identity-based key pair derivation algorithm first proposed by ...Sakai and Kasahara. We show how this key agreement can be used in either escrowed or escrowless mode. We also describe conditions under which users of different Key Generation Centres can agree on a shared secret key. We give an overview of existing two-party key agreement protocols, and compare our new scheme with existing ones in terms of computational cost and storage requirements.
Abstract
Background
Periportal fibrosis (PPF) is the major pathological consequence of Schistosoma mansoni infection. The Coutinho index—the alkaline phosphatase (ALP) to platelet ratio (ALP/upper ...limit of normality {ULN}/platelet count 106/L x 100)—was validated. Validation consisted of modest laboratory tests to predict advanced PPF.
Methods
A total of 378 individuals from an endemic area of Brazil with a previous history of the disease and/or a positive parasitological examination were evaluated. We used ultrasound examination as the gold standard for classification of the PPF pattern and measured the biological markers of the index.
Results
Forty-one individuals (10.8%) without PPF, 291 (77%) with moderate PPF and 46 (12.2%) with advanced PPF, were identified. ALP and platelet count were used for the index. The cut-off point ≥0.228 predicted the presence of fibrosis with an area under the receiver operating characteristic curve (AUROC) of 0.56, sensitivity of 68.6% and specificity of 46.3%. There was an absence of PPF in 46.3% of individuals without fibrosis and the presence of PPF in 68.5% of cases with moderate and advanced ultrasound fibrosis. The identification of advanced fibrosis with a cut-off point ≥0.316 revealed an AUROC curve of 0.70, sensitivity of 67.4% and specificity of 68.3%, thus confirming the advanced phase in 65.2% of cases compared with ultrasound.
Conclusion
The Coutinho index was able to predict advanced PPF in most individuals. It is valid as a new tool, uses routine laboratory tests and therefore is more accessible for screening patients with a severe form of the disease in endemic areas.
The prevalence of obesity has increased to epidemic status worldwide. Thousands of morbidly obese individuals undergo bariatric surgery for sustained weight loss; however, mid- and long-term outcomes ...of this surgery are still uncertain. Our objective was to estimate the 10-year mortality rate, and determine risk factors associated with death in young morbidly obese adults who underwent bariatric surgery. All patients who underwent open Roux-in-Y gastric bypass surgery between 2001 and 2010, covered by an insurance company, were analyzed to determine possible associations between risk factors present at the time of surgery and deaths related and unrelated to the surgery. Among the 4344 patients included in the study, 79% were female with a median age of 34.9 years and median body mass index (BMI) of 42 kg/m(2). The 30-day and 10-year mortality rates were 0.55 and 3.34%, respectively, and 53.7% of deaths were related to early or late complications following bariatric surgery. Among these, 42.7% of the deaths were due to sepsis and 24.3% to cardiovascular complications. Male gender, age ≥50 years, BMI ≥50 kg/m(2), and hypertension significantly increased the hazard for all deaths (P<0.001). Age ≥50 years, BMI ≥50 kg/m(2), and surgeon inexperience elevated the hazard of death from causes related to surgery. Male gender and age ≥50 years were the factors associated with increased mortality from death not related to surgery. The overall risk of death after bariatric surgery was quite low, and half of the deaths were related to the surgery. Older patients and superobese patients were at greater risk of surgery-related deaths, as were patients operated on by less experienced surgeons.
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