Intelligent tutoring systems for word problem solving in COVID-19 days: could they have been (part of) the solution?

The COVID-19 pandemic led to the lockdown of schools in many countries, forcing teachers and students to carry out educational activities remotely. In the case of mathematics, developing remote instruction based on both synchronous and asynchronous technological solutions has proven to be an extremely complex challenge. Specifically, this was the case in topics such as word problem solving, as this domain requires intensive supervision and feedback from the teacher. In this piece of research, we present an evaluation of how technology is employed in the teaching of mathematics, with particular relevance to learning during the pandemic. For that purpose, we conducted a systematic review, revealing the almost complete absence of experiments in which the use of technology is not mediated by the teacher. These results reflect a pessimistic vision within the field of mathematics education about the possibilities of learning when the student uses technology autonomously. Bringing good outcomes out of a bad situation, the pandemic crisis may represent a turning point from which to start directing the research gaze towards technological environments such as those mediated by artificial intelligence. As an example, we provide a study illustrating to what extent intelligent tutoring systems can be cost-effective compared to one-to-one human tutoring and mathematic learning-oriented solutions for intensive supervision in the teaching of word problem solving, especially appropriate for remote settings. Despite the potential of these technologies, the experience also showed that student socioeconomic level was a determining factor in the participation rate with an intelligent tutoring system, regardless of whether or not the administration guaranteed students' access to technological resources during the COVID-19 situation.

A Methodology for Remote Microwave Sterilization Applicable to the Coronavirus and Other Pathogens Using Retrodirective Antenna Arrays.

This paper describes an innovative remote surface sterilization approach applicable to the new coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The process is based on the application of a liquid film on the surface or object under sterilization (OUS). A beacon signal is used to self-steer the transmitted power from the designed retrodirective antenna array (RDA) towards the OUS using circularly polarized fields; then, the sterilization is completed by raising and maintaining the required temperature for a certain time. Results suggest that the process takes 5 minutes or less for an angular coverage range over 60 degrees whilst abiding by the relevant safety protocols. This paper also models the power incident onto the OUS, providing consistent results with full-wave simulations. A practical RDA system is developed using a 2 × 1 microstrip patch array operating at 2.5 GHz and tested through the positioning of a representative target surface. Measurements, developed by sampling the power transmitted by the heterodyne RDA, are reported for various distances and angles, operating in the near-field of the system. To further validate the methodology, an additional experiment investigating virus deactivation through microwave heating was also developed. Measurements have been performed with an open cavity microwave oven on the Coronavirus (strain 229E) and egg white protein in a cuvette. This demonstrates that the temperature increases of aqueous films up to 70 [Formula: see text]C by remote microwave-induced heat can denature proteins and deactivate viruses. Possible applications of the method include sterilization of ambulances, medical equipment, and internet of things (IoT) devices.

Mercury in Populations of River Dolphins of the Amazon and Orinoco Basins.

In the Amazon and Orinoco basins, mercury has been released from artisanal and industrial gold mining since the Colonial time, as well as a result of deforestation and burning of primary forest, that release natural deposits of methyl mercury, affecting the local aquatic vertebrate fauna. This study reports the presence of mercury in river dolphins' genera Inia and Sotalia. Mercury concentrations were analysed in muscle tissue samples collected from 46 individuals at the Arauca and Orinoco Rivers (Colombia), the Amazon River (Colombia), a tributary of the Itenez River (Bolivia) and from the Tapajos River (Brazil). Ranges of total mercury (Hg) concentration in muscle tissue of the four different taxa sampled were: I. geoffrensis humboldtiana 0.003-3.99 mg kg-1 ww (n = 21, Me = 0.4), I. g. geoffrensis 0.1-2.6 mg kg-1 ww (n = 15, Me = 0.55), I. boliviensis 0.03-0.4 mg kg-1 ww (n = 8, Me = 0.1) and S. fluviatilis 0.1-0.87 mg kg-1 ww (n = 2, Me = 0.5). The highest Hg concentration in our study was obtained at the Orinoco basin, recorded from a juvenile male of I. g. humboldtiana (3.99 mg kg-1 ww). At the Amazon basin, higher concentrations of mercury were recorded in the Tapajos River (Brazil) from an adult male of I. g. geoffrensis (2.6 mg kg-1 ww) and the Amazon River from an adult female of S. fluviatilis (0.87 mg kg-1 ww). Our data support the presence of total Hg in river dolphins distributed across the evaluated basins, evidencing the role of these cetaceans as sentinel species and bioindicators of the presence of this heavy metal in natural aquatic environments.

Identification of a Novel Elastin-Degrading Enzyme from the Fish Pathogen Flavobacterium psychrophilum.

Hydrolytic extracellular enzymes degrading host tissues potentially play a role in bacterial pathogenesis. Flavobacterium psychrophilum is an important bacterial pathogen of salmonid fish reared in freshwater throughout the world. Diversity among isolates has been described at the phenotypic, serological, and genomic levels, but the links between these various traits remain poorly understood. Using a genome-wide association study, we identified a gene encoding a novel elastinolytic enzyme in F. psychrophilum To formally demonstrate enzymatic activity, this gene (FP0506 from strain JIP 02/86) was expressed in the elastinolysis-deficient strain OSU THCO2-90, resulting in proficient elastin-degrading cells. The encoded protein is predicted to be a cell-surface-exposed lipoprotein with no homology to previously reported elastases. FP0506 might belong to the zincin tribe and gluzincin clan of metalloproteases, and this new elastase-encoding gene seems to be present only in some members of the family FlavobacteriaceaeIMPORTANCE Elastin is an important proteinaceous component of vertebrate connective tissues (e.g., blood vessels, lung, and skin), to which it confers elasticity. Elastases have been identified in a number of pathogenic bacteria. They are thought to be required for tissue penetration and dissemination, acting as "spreading factors." Flavobacterium psychrophilum is a devastating bacterial pathogen of salmonid fish (salmon and trout) that is responsible for severe economic losses worldwide. This pathogen displays strong proteolytic activities. Using a variety of techniques, including genome comparisons, we identified a gene encoding a novel elastase in F. psychrophilum The encoded protein is predicted to be a cell-surface-exposed lipoprotein with no homology to previously reported elastases. In addition, this elastase likely belongs to a new family of proteases that seems to be present only in some members of this important group of bacteria.

Chronic pain and cannabinoids. Great expectations or a christmas carol.

The discovery of the endocannabinoid system nearly three decades ago generated great interest among pain scientists. Moreover, its analogy with the opioid system in terms of evolutionary preservation, tissue localization and analgesic activity enabled a vast new field for the development of medicines addressed to those types of pain that still nowadays are difficult to manage. However, the main disadvantage that hampers the use of cannabinergic drugs as analgesics is their identification with recreational use, besides their psychotomimetic actions. Pain has traditionally been classified attending to the ailment duration (acute or chronic) and drugs are used according to the intensity of the pain to treat, but it is also important to target the mechanism involved despite the intensity or duration of pain. The present chapter reviews the study and use of cannabinoids attending separately to four classic types of pain: nociceptive, inflammatory, neuropathic and oncological, considering basic research (pain animal models) as well as clinical practice.

[Guided and computer-assisted implant surgery and prosthetic: The continuous digital workflow]. / Chirurgie implantaire et prothèse guidées et assistées par ordinateur : le flux numérique continu.

INTRODUCTION: New continuous digital workflow protocols of guided and computer-assisted implant surgery improve accuracy of implant positioning. TECHNICAL PROCEDURE: The design of the future prosthesis is based on the available prosthetic space, gingival height and occlusal relationship with the opposing and adjacent teeth. The implant position and length depend on volume, density and bone quality, gingival height, tooth-implant and implant-implant distances, implant parallelism, axis and type of the future prosthesis. The crown modeled on the software will therefore serve as a guide to the future implant axis and not the reverse. The guide is made by 3D printing. The software determines surgical protocol with the drilling sequences. The unitary or plural prosthesis, modeled on the software and built before surgery, is loaded directly after implant placing, if needed. DISCUSSION: These protocols allow for a full continuity of the digital workflow. The software provides the surgeon and the dental technician a total freedom for the prosthetic-surgery guide design and the position of the implants. The prosthetic project, occlusal and aesthetic, taking the bony and surgical constraints into account, is optimized. The implant surgery is simplified and becomes less "stressful" for the patient and the surgeon. Guided and computer-assisted surgery with continuous digital workflow is becoming the technique of choice to improve the accuracy and quality of implant rehabilitation.

Cancer Incidence in Heart Transplant Recipients With Previous Neoplasia History.

Neoplasm history increases morbidity and mortality after solid organ transplantation and has disqualified patients from transplantation. Studies are needed to identify factors to be considered when deciding on the suitability of a patient with previous tumor for heart transplantation. A retrospective epidemiological study was conducted in heart transplant (HT) recipients (Spanish Post-Heart Transplant Tumor Registry) comparing the epidemiological data, immu-nosuppressive treatments and incidence of post-HT tumors between patients with previous malignant noncardiac tumor and with no previous tumor (NPT). The impact of previous tumor (PT) on overall survival (OS) was also assessed. A total of 4561 patients, 77 PT and 4484 NPT, were evaluated. The NPT group had a higher proportion of men than the PT group (p < 0.001). The incidence of post-HT tumors was 1.8 times greater in the PT group (95% confidence interval [CI] 1.2-2.6; p < 0.001), mainly due to the increased risk in patients with a previous hematologic tumor (rate ratio 2.3, 95% CI 1.3-4.0, p < 0.004). OS during the 10-year posttransplant period was significantly lower in the PT than the NPT group (p = 0.048) but similar when the analysis was conducted after a first post-HT tumor was diagnosed. In conclusion, a history of PT increases the incidence of post-HT tumors and should be taken into account when considering a patient for HT.

Isolation of oxalotrophic bacteria associated with Varroa destructor mites.

UNLABELLED: Bacteria associated with varroa mites were cultivated and genotyped by 16S RNA. Under our experimental conditions, the cultivable bacteria were few in number, and most of them proved to be fastidious to grow. Cultivation with seven different media under O2 /CO2 conditions and selection for colony morphology yielded a panel of species belonging to 13 different genera grouped in two different phyla, proteobacteria and actinobacteria. This study identified one species of actinobacteria that is a known commensal of the honey bee. Some isolates are oxalotrophic, a finding that may carry ramifications into the use of oxalic acid to control the number of phoretic mites in the managed colonies of honey bees. SIGNIFICANCE AND IMPACT OF THE STUDY: Oxalic acid, legally or brevi manu, is widely used to control phoretic Varroa destructor mites, a major drive of current honey bees' colony losses. Unsubstantiated by sanctioned research are rumours that in certain instances oxalic acid is losing efficacy, forcing beekeepers to increase the frequency of treatments. This investigation fathoms the hypothesis that V. destructor associates with bacteria capable of degrading oxalic acid. The data show that indeed oxalotrophy, a rare trait among bacteria, is common in bacteria that we isolated from V. destructor mites. This finding may have ramifications in the use of oxalic acid as a control agent.

Health-related quality of life, social support, and caregiver burden between six and 120 months after heart transplantation: a Spanish multicenter cross-sectional study.

A multicenter cross-sectional study was conducted to determine the current heart transplant (HTx) outcomes in Spain. Clinical and functional status, health-related quality of life (HRQoL), social support, and caregiver burden were analyzed in 303 adult transplant recipients (77.9% males) living with one functioning graft. Mean age at time of HTx (SD) was 56.4 (11.4) years, and the reason for transplantation in all patients was congestive heart failure. All patients had received a first heart transplant 6 (± 1), 12 (± 2), 36 (± 6), 60 (± 10), or 120 (± 20) months previously. Participants completed the Kansas City Cardiomyopathy Questionnaire (KCCQ), the EQ-5D, the Duke-UNC Functional Social Support Questionnaire, and the Zarit Caregiver Burden Scale. Reasonable HRQoL, social support, and caregiver burden levels were found at all time points, although a slight decrease in HRQoL was recorded at 120 months (p ≤ 0.033). Multivariate regression analyses showed that complications, comorbidities, and hospitalizations were associated with HRQoL (EQ-5D: 48.4% of explained variance, F4,164 = 38.46, p < 0.001; KCCQ overall summary score: 45.0%, F3,198 = 54.073, p < 0.001). Patient functional capabilities and complications affected caregiver burden (p < 0.05). In conclusion, HTx patients reported reasonable levels of HRQoL with low caregiver burden. Clinical variables related to these outcomes included functional status, complications, and number of admissions.

Paratransgenesis feasibility in the honeybee (Apis mellifera) using Fructobacillus fructosus commensal.

AIMS: To establish the molecular tools for honeybee paratransgenesis. METHODS AND RESULTS: Commensal bacteria were isolated from two honeybees. Based on 16S ribosomal RNA sequence analysis, some isolates were identified as Fructobacillus fructosus, Lactobacillus kunkeei, Gilliamella apicola, Acinetobacter spp, Arthrobacter spp and Pseudomonas spp. Rolling circle and theta replicons were successfully introduced into F. fructosus and Lact. kunkeei. Green fluorescent protein was expressed into both species. The 7·3 Kb Lactococcus lactis subsp. cremoris MG1363 operon encoding a cluster of five genes involved in the metabolism of galactose via the Leloir pathway was functionally expressed into a non-galactose-fermenting strain of F. fructosus enabling it to grow on galactose as a sole carbon source. CONCLUSIONS: Fructophilic lactic acid bacteria, F. fructosus and Lact. kunkeei, are amenable to extensive genetic manipulations. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study demonstrating the feasibility of genetically engineering honeybee commensals, thus establishing the tools necessary for honeybee paratransgenesis.

[Bone graft reconstruction for posterior mandibular segment using the formwork technique]. / Greffes osseuses des secteurs mandibulaires postérieurs par technique de « coffrage ¼.

INTRODUCTION: Pre-implant bone graft in posterior mandibular segments is difficult because of masticatory and lingual mechanical constraints, because of the limited bone vascularization, and because of the difficulty to cover it with the mucosa. The formwork technique is especially well adapted to this topography. TECHNICAL NOTE: The recipient site is abraded with a drill. Grooves are created to receive and stabilize the grafts. The bone grafts were harvested from the ramus. The thinned cortices are assembled in a formwork and synthesized by mini-plates. The gaps are filled by bone powder collected during bone harvesting. DISCUSSION: The bone volume reconstructed with the formwork technique allows anchoring implants more than 8mm long. The proximity of the inferior alveolar nerve does not contra indicate this technique. The formwork size and its positioning on the alveolar crest can be adapted to prosthetic requirements by using osteosynthesis plates. The lateral implant walls are supported by the formwork cortices; the implant apex is anchored on the native alveolar crest. The primary stability of implants is high, and the torque is important. The ramus harvesting decreases operative risks.

Chronic renal dysfunction in maintenance heart transplant patients: the ICEBERG study.

Chronic renal dysfunction (CRD) is a major complication after heart transplantation. We sought to describe the renal function over time, to assess the risk factors associated with CRD development, and to evaluate the clinical attitudes on diagnosis and treatment of CRD. A retrospective, cross-sectional, multicenter study was conducted in 13 outpatient clinics in Spain. A total of 244 heart recipients who survived more than 2 years after transplantation were included. Post-transplantation follow-up was 7.7 years (range: 2-22 years). CRD was diagnosed in 32.4% of patients at a mean of 3.3 years after transplantation. Serum creatinine increased 0.1 ± 0.2 mg/dL per year in CRD group compared with 0.0 ± 0.2 mg/dL per year in non-CRD group (P = .003) and glomerular filtration rate decreased -1.5 ± 4.3 mL/min/1.73 m(2) per year in CRD group versus -0.1 ± 4.8 mL/min/1.73 m(2) per year in non-CRD group (P = .027). After CRD diagnosis, major changes in immunosuppression based on calcineurin inhibitors reduction were instituted in 46.8% of patients. Multivariate model identified recipient age (P < .0001), female sex (P = .0398), and time since transplant (P < .0001) as predictors of CRD. In conclusion, the prevalence of CRD in long-term heart recipient survivors was quite high. CRD was associated with nonmodifiable factors (age, gender, and time since transplant).

Daidzein has neuroprotective effects through ligand-binding-independent PPARγ activation.

Phytoestrogens are a group of plant-derived compounds that include mainly isoflavones like daidzein. Phytoestrogens prevent neuronal damage and improve outcome in experimental stroke; however, the mechanisms of this neuroprotective action have not been fully elucidated. In this context, it has been postulated that phytoestrogens might activate the peroxisome proliferator-activated receptor-γ (PPARγ), which exerts neuroprotective effects in several settings. The aim of this study was to determine whether the phytoestrogen daidzein elicits beneficial actions in neuronal cells by mechanisms involving activation of PPARγ. Our results show that daidzein (0.05-5 µM) decreases cell death induced by exposure to oxygen-glucose deprivation (OGD) from rat cortical neurons and that improves synaptic function, in terms of increased synaptic vesicle recycling at nerve terminals, being both effects inhibited by the PPARγ antagonist T0070907 (1 µM). In addition, this phytoestrogen activated PPARγ in neuronal cultures, as shown by an increase in PPARγ transcriptional activity. Interestingly, these effects were not due to binding to the receptor ligand site, as shown by a TR-FRET PPARγ competitive binding assay. Conversely, daidzein increased PPARγ nuclear protein levels and decreased cytosolic ones, suggesting nuclear translocation. We have used the receptor antagonist (RE) fulvestrant to study the neuroprotective participation of daidzein via estrogen receptor and at least in our model, we have discarded this pathway. These results demonstrate that the phytoestrogen daidzein has cytoprotective properties in neurons, which are due to an increase in PPARγ activity not mediated by direct binding to the receptor ligand-binding domain but likely due to post-translational modifications affecting its subcellular location and not depending to the RE and it is not additive with the agonist rosiglitazone.

[Modelization of bone graft reconstruction for posterior mandibular segment using the Simplant® software]. / Modélisation des techniques de reconstruction par greffes osseuses des secteurs mandibulaires postérieurs avec le logiciel Simplant(®).

INTRODUCTION: Pre-implant reconstruction techniques of edentulous molar mandibular ridges take into account the height and the width of the initial ridge, but not the initial geometry. The Simplant(®) software allows modeling these techniques by taking into account this geometry. TECHNICAL NOTE: Four surgical techniques for crestal volume reconstruction (apposition, interposition, distraction, formwork) were used on seven hemi-mandibles and modeled with the Simplant(®) software. This reconstructed volume was visualized according to the initial crestal geometry. The average gain in height was 4.1mm for the onlay graft, 2.3mm for the interposition graft, 4mm for distraction, 5.1mm for the boxing. The average gain of crestal width was -0.3mm for the onlay graft, 1mm for the interposition, -0.5mm for the distraction, and 1.3mm for the boxing. DISCUSSION: Modeling with the Simplant(®) software shows that boxing technique gives the closest bone reconstruction to the ideal crestal geometry, whatever the initial crestal geometry.

M cell-targeted mucosal vaccine strategies.

Immune responses in the aerodigestive tract are characterized by production and transport of specific IgA antibodies across the epithelium to act as a first line of defense against pathogens in the external environment. To sample antigens on mucosal surfaces in the intestine and upper respiratory tract, the immune system relies on a close collaboration between specialized antigen-sampling epithelial M cells and lymphoid cells. Depending on various factors, local antigen presentation in the mucosal tissue leads to tolerance or initiation of an active immune response. Recently, molecules that could be used to target vaccine antigens to apical M cell surfaces have been identified. Here we review the M cell-targeted vaccine strategy, an approach that could be used to enhance uptake and efficacy of vaccines delivered in the nasal cavity or intestine.

Risk factors associated with cytomegalovirus infection in heart transplant patients: a prospective, epidemiological study.

BACKGROUND: The objectives of this epidemiological, prospective study were to describe the characteristics of cytomegalovirus (CMV) infection in heart transplant (HT) recipients and to identify the variables that may influence the development of CMV viremia and CMV disease in these patients. METHODS: HT recipients ≥18 years of age (n=199) were included in the study. Variables studied included CMV serostatus, immunosuppressive treatment, and administration of anti-CMV prophylaxis. RESULTS: The mean age of the population was 52 years, and 84% were males. Immunosuppressive regimens were administered as induction therapy to 92.5% of patients; 88.5% of patients received calcineurin inhibitors as maintenance therapy. Anti-CMV treatment was given to 59% of 199 patients as prophylaxis (70%), preemptive therapy (10%), or to treat CMV infection (20%). Overall, 43% of patients had at least 1 positive viremia test. No patient with a high-risk serostatus (donor+/recipient-) receiving prophylaxis developed CMV syndrome, and only 2.5% of 199 patients developed CMV invasive disease. Multivariate analysis showed that having a positive donor CMV serostatus was associated with an increased risk of developing CMV viremia (P<0.012), while use of mammalian target of rapamycin (mTOR) inhibitors was associated with a decreased risk (P=0.005). CONCLUSIONS: In a population of HT recipients, the CMV infection rate was similar to that seen in previous studies, but the progression to overt CMV disease was very low. Having a CMV-positive donor was identified as an independent risk factor for developing CMV viremia, while the use of mTOR inhibitors was protective against viremia.

Incidence and risk factors for nonmelanoma skin cancer after heart transplantation.

INTRODUCTION: The incidence of skin cancer in heart transplant (HT) patients is higher than in the general population, reversing the proportion of cutaneous squamous cell carcinoma (SCC) and basal cell carcinoma (BCC) with a predominance of the former. The etiologic role of new immunosuppressants is not well known. We sought to ascertain the incidence of SCC and BCC in HT patients and the risk factors for its occurrence. PATIENTS AND METHODS: We report the incidence of all types of post-HT skin cancer, SCC, and BCC among adult HT patients in Spain (4089 subjects) as well as the influence of gender, age at heart transplant, immunosuppression, and sunlight exposure. RESULTS: The incidence rates of SCC and BCC, per 1000 persons/year, were 8.5 and 5.2, respectively. Males had a higher risk of SCC but not BCC. Induction therapy increased the risk of SCC and BCC. The relative risk of mycophenolate mofetil (MMF) was 0.3 (0.2-0.6; P<.0005) and azathioprine (AZA) 1.8 (1.2-2.7; P<.0032) for SCC, whereas tacrolimus and cyclosporine showed no difference. The relative risk of BCC was not affected by any immunosuppressant. CONCLUSION: Age at transplantation>45 years, induction therapy use, and high sunshine zone were risk factors for both SCC and BCC. Different immunosuppressive agents have different risks of nonmelanoma skin cancer, as AZA increases the risk of SCC and MMF is a protective factor. The relative risk of BCC was not affected by any immunosuppressor.

dltA gene mutation in the teichoic acids alanylation system of Lactococcus garvieae results in diminished proliferation in its natural host.

The dltABCD cluster is involved in the d-alanylation of teichoic acids in gram positive bacteria. In order to determine the role of this alanylation in the physiology and virulence of Lactococcus garvieae, a previously isolated dltA Delta Tn917 signature tagged mutagenesis (STM) clone was analyzed. RT-PCR results revealed that dltABCD genes form an operon. No major differences could be established between the parental and mutant strains with respect to growth rate, autolytic properties, and susceptibility to acid conditions, lysozyme treatment, anionic detergents, or oxidant agents. However, the dltA mutant was more susceptible to nisin than the parental strain, with minimum inhibitory concentration (MIC) values of 8 and 16 microg/ml, respectively. Less proliferation of the mutant was observed in in vivo competence index experiments (CI=0.08). Furthermore, the mutant strain had a 50% lethal dose (LD(50)) 3-fold that of the parental strain. These results, together with the fact that the dltA Delta Tn917 mutant was isolated as a STM clone, reveal that the dltA locus of Lactococcus garvieae is required for full growth and pathogenesis on rainbow trout.