Effect of Pressure on Structural, Elastic and Electronic Properties of Perovskite PbTiO3

We study the effect of pressure on Structural, elastic and electronic properties of Cubic and Tetragonal Perovskite using density function theory. The equilibrium parameters obtained are in good agreement with the available literature both experimental and theoretical. We found out that there is transition from tetragonal to cubic at a pressure of around 30GPa. Both crystals are stable in the pressure range of this study (0 – 50 GPa), and the stability increases with increasing pressure. The bulk modulus (B), Young modulus (E) and Shear modulus (G) all increase with increasing pressure. The band-gap increases and decrease around (X-Gamma) and (M-Gamma) for the case of Cubic and decrease for the case of Tetragonal Crystal around (X-Gamma), (Z-Gamma) and (Z-X) which converges at pressure of around 30GPa

Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London

Surgical site infection after gastrointestinal surgery in high-income, middle-income, and low-income countries: a prospective, international, multicentre cohort study

Background: Surgical site infection (SSI) is one of the most common infections associated with health care, but its importance as a global health priority is not fully understood. We quantified the burden of SSI after gastrointestinal surgery in countries in all parts of the world. Methods: This international, prospective, multicentre cohort study included consecutive patients undergoing elective or emergency gastrointestinal resection within 2-week time periods at any health-care facility in any country. Countries with participating centres were stratified into high-income, middle-income, and low-income groups according to the UN's Human Development Index (HDI). Data variables from the GlobalSurg 1 study and other studies that have been found to affect the likelihood of SSI were entered into risk adjustment models. The primary outcome measure was the 30-day SSI incidence (defined by US Centers for Disease Control and Prevention criteria for superficial and deep incisional SSI). Relationships with explanatory variables were examined using Bayesian multilevel logistic regression models. This trial is registered with ClinicalTrials.gov, number NCT02662231. Findings: Between Jan 4, 2016, and July 31, 2016, 13 265 records were submitted for analysis. 12 539 patients from 343 hospitals in 66 countries were included. 7339 (58·5%) patient were from high-HDI countries (193 hospitals in 30 countries), 3918 (31·2%) patients were from middle-HDI countries (82 hospitals in 18 countries), and 1282 (10·2%) patients were from low-HDI countries (68 hospitals in 18 countries). In total, 1538 (12·3%) patients had SSI within 30 days of surgery. The incidence of SSI varied between countries with high (691 [9·4%] of 7339 patients), middle (549 [14·0%] of 3918 patients), and low (298 [23·2%] of 1282) HDI (p < 0·001). The highest SSI incidence in each HDI group was after dirty surgery (102 [17·8%] of 574 patients in high-HDI countries; 74 [31·4%] of 236 patients in middle-HDI countries; 72 [39·8%] of 181 patients in low-HDI countries). Following risk factor adjustment, patients in low-HDI countries were at greatest risk of SSI (adjusted odds ratio 1·60, 95% credible interval 1·05–2·37; p=0·030). 132 (21·6%) of 610 patients with an SSI and a microbiology culture result had an infection that was resistant to the prophylactic antibiotic used. Resistant infections were detected in 49 (16·6%) of 295 patients in high-HDI countries, in 37 (19·8%) of 187 patients in middle-HDI countries, and in 46 (35·9%) of 128 patients in low-HDI countries (p < 0·001). Interpretation: Countries with a low HDI carry a disproportionately greater burden of SSI than countries with a middle or high HDI and might have higher rates of antibiotic resistance. In view of WHO recommendations on SSI prevention that highlight the absence of high-quality interventional research, urgent, pragmatic, randomised trials based in LMICs are needed to assess measures aiming to reduce this preventable complication

Impact of opioid-free analgesia on pain severity and patient satisfaction after discharge from surgery: multispecialty, prospective cohort study in 25 countries

Background: Balancing opioid stewardship and the need for adequate analgesia following discharge after surgery is challenging. This study aimed to compare the outcomes for patients discharged with opioid versus opioid-free analgesia after common surgical procedures.Methods: This international, multicentre, prospective cohort study collected data from patients undergoing common acute and elective general surgical, urological, gynaecological, and orthopaedic procedures. The primary outcomes were patient-reported time in severe pain measured on a numerical analogue scale from 0 to 100% and patient-reported satisfaction with pain relief during the first week following discharge. Data were collected by in-hospital chart review and patient telephone interview 1 week after discharge.Results: The study recruited 4273 patients from 144 centres in 25 countries; 1311 patients (30.7%) were prescribed opioid analgesia at discharge. Patients reported being in severe pain for 10 (i.q.r. 1-30)% of the first week after discharge and rated satisfaction with analgesia as 90 (i.q.r. 80-100) of 100. After adjustment for confounders, opioid analgesia on discharge was independently associated with increased pain severity (risk ratio 1.52, 95% c.i. 1.31 to 1.76; P &lt; 0.001) and re-presentation to healthcare providers owing to side-effects of medication (OR 2.38, 95% c.i. 1.36 to 4.17; P = 0.004), but not with satisfaction with analgesia (beta coefficient 0.92, 95% c.i. -1.52 to 3.36; P = 0.468) compared with opioid-free analgesia. Although opioid prescribing varied greatly between high-income and low- and middle-income countries, patient-reported outcomes did not.Conclusion: Opioid analgesia prescription on surgical discharge is associated with a higher risk of re-presentation owing to side-effects of medication and increased patient-reported pain, but not with changes in patient-reported satisfaction. Opioid-free discharge analgesia should be adopted routinely

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Résonances non linéaires et certaines de leurs applications en traitement de l'information

Ces dernières années, un intérêt considérable a été consacré à l'étude des phénomènes de résonance dans les systèmes dynamiques non linéaires. Parmi les résonances non linéaires, la plus étudiée est sans aucun doute la résonance stochastique, qui traduit la particularité des systèmes non linéaires à utiliser une quantité appropriée de bruit pour améliorer leur réponse à une excitation subliminale. Plus tardivement, il a été observé qu'une perturbation haute fréquence pouvait remplacer le bruit, ce qui donna naissance à l'effet de résonance vibrationnelle. Même si cette forme de résonance a été mise en évidence dans de nombreux systèmes et dans différents contextes depuis plus de deux décennies maintenant, l'étude de ce phénomène continue de susciter l'intérêt des chercheurs. C'est l'objectif de cette thèse, qui analyse numériquement l'apparition de cette résonance dans deux systèmes non linéaires, ainsi que ses applications dans le cadre de la perception d'images subliminales. Notre première étude numérique porte ainsi sur un système mécanique représentant une particule de masse donnée. Que ce soit dans le cas d'un amortissement linéaire ou spatialement non linéaire, nous avons mis en évidence l'existence d'une masse critique au-delà de laquelle la résonance vibrationnelle cesse d'exister. Notre seconde étude porte sur l’impact de la non linéarité sur la résonance d’un modèle de circuit de Chua. Nous avons principalement montré numériquement qu’une non linéarité du type sinusoïdale tronquée permettait d’obtenir une résonance vibrationnelle plus marquée que la non linéarité usuelle du type dent de scie. Par ailleurs, quand deux fréquences proches excitent le système, en plus d’une résonance à chacune de ces fréquences, il apparait une résonance à une fréquence plus faible, qualifiée de fantôme. Enfin, nous avons établi qu'il était possible d'obtenir une bien meilleure perception d’images subliminales au travers d’un dispositif à seuil tirant profit de la résonance vibrationnelle plutôt que d'un dispositif basé sur la résonance stochastique.The study of resonance phenomena in nonlinear dynamical systems has drawn considerable attention for years. The most studied nonlinear resonance is undoubtedly the famous stochastic resonance, which consists of perturbing a nonlinear system with an appropriate amount of noise to enhance the detection of a subthreshold input signal. Since the introduction of stochastic resonance in the context of climate dynamics, it was later observed that a deterministic high frequency perturbation can replace noise leading to vibrational resonance. Even if this latter resonance was investigated in many areas of science for more than two decades now, it is still receiving attentions. It is the subject of this thesis, which numerically analyzes the occurrence of this phenomenon in two different nonlinear systems, and which suggests applications in the context of subthreshold images perception. First, we analyze the motion of a particle with a given mass which is submitted to a nonlinear force deriving from a double-well potential. For both considered cases of linear and nonlinear space-dependent damping, we establish that there exists a critical mass beyond which vibrational resonance ceases to exist. Next, we analyze how the nonlinearity affects vibrational resonance in the Chua’s circuit model. Especially, we show that better resonances can be achieved when Chua's system experiences a truncated sinusoidal nonlinearity instead of the conventional sawtooth nonlinearity. Moreover, when the system driving consists of two close low frequencies, we observe that the high frequency perturbation can induce resonances at the two input low frequencies but also at a lower frequency via the mechanisms of vibrational resonance and ghost-vibrational resonance. Lastly, we consider the perception of subthreshold images through perturbed threshold detectors. In terms of image perception, we show that detectors which are based on vibrational resonance clearly outperform detectors based on stochastic resonance

Résonances non linéaires et certaines de leurs applications en traitement de l'information

The study of resonance phenomena in nonlinear dynamical systems has drawn considerable attention for years. The most studied nonlinear resonance is undoubtedly the famous stochastic resonance, which consists of perturbing a nonlinear system with an appropriate amount of noise to enhance the detection of a subthreshold input signal. Since the introduction of stochastic resonance in the context of climate dynamics, it was later observed that a deterministic high frequency perturbation can replace noise leading to vibrational resonance. Even if this latter resonance was investigated in many areas of science for more than two decades now, it is still receiving attentions. It is the subject of this thesis, which numerically analyzes the occurrence of this phenomenon in two different nonlinear systems, and which suggests applications in the context of subthreshold images perception. First, we analyze the motion of a particle with a given mass which is submitted to a nonlinear force deriving from a double-well potential. For both considered cases of linear and nonlinear space-dependent damping, we establish that there exists a critical mass beyond which vibrational resonance ceases to exist. Next, we analyze how the nonlinearity affects vibrational resonance in the Chua’s circuit model. Especially, we show that better resonances can be achieved when Chua's system experiences a truncated sinusoidal nonlinearity instead of the conventional sawtooth nonlinearity. Moreover, when the system driving consists of two close low frequencies, we observe that the high frequency perturbation can induce resonances at the two input low frequencies but also at a lower frequency via the mechanisms of vibrational resonance and ghost-vibrational resonance. Lastly, we consider the perception of subthreshold images through perturbed threshold detectors. In terms of image perception, we show that detectors which are based on vibrational resonance clearly outperform detectors based on stochastic resonance.Ces dernières années, un intérêt considérable a été consacré à l'étude des phénomènes de résonance dans les systèmes dynamiques non linéaires. Parmi les résonances non linéaires, la plus étudiée est sans aucun doute la résonance stochastique, qui traduit la particularité des systèmes non linéaires à utiliser une quantité appropriée de bruit pour améliorer leur réponse à une excitation subliminale. Plus tardivement, il a été observé qu'une perturbation haute fréquence pouvait remplacer le bruit, ce qui donna naissance à l'effet de résonance vibrationnelle. Même si cette forme de résonance a été mise en évidence dans de nombreux systèmes et dans différents contextes depuis plus de deux décennies maintenant, l'étude de ce phénomène continue de susciter l'intérêt des chercheurs. C'est l'objectif de cette thèse, qui analyse numériquement l'apparition de cette résonance dans deux systèmes non linéaires, ainsi que ses applications dans le cadre de la perception d'images subliminales. Notre première étude numérique porte ainsi sur un système mécanique représentant une particule de masse donnée. Que ce soit dans le cas d'un amortissement linéaire ou spatialement non linéaire, nous avons mis en évidence l'existence d'une masse critique au-delà de laquelle la résonance vibrationnelle cesse d'exister. Notre seconde étude porte sur l’impact de la non linéarité sur la résonance d’un modèle de circuit de Chua. Nous avons principalement montré numériquement qu’une non linéarité du type sinusoïdale tronquée permettait d’obtenir une résonance vibrationnelle plus marquée que la non linéarité usuelle du type dent de scie. Par ailleurs, quand deux fréquences proches excitent le système, en plus d’une résonance à chacune de ces fréquences, il apparait une résonance à une fréquence plus faible, qualifiée de fantôme. Enfin, nous avons établi qu'il était possible d'obtenir une bien meilleure perception d’images subliminales au travers d’un dispositif à seuil tirant profit de la résonance vibrationnelle plutôt que d'un dispositif basé sur la résonance stochastique

Investigating the Mediating Roles of Income Level and Technological Innovation in Africa’s Sustainability Pathways Amidst Energy Transition, Resource Abundance, and Financial Inclusion

The global environment faces the issue of sustainability arising from the persistent growth rates in general production levels. Hence, there is the need to resolve the growth environment conflicts in order to enhance the sustainability of the current and future generations. This study presents the first empirical analysis on the dynamic impacts of non-renewable and renewable energy, total resource rents, population growth, human capital, and financial inclusion on environmental quality in Sub-Saharan Africa (SSA) with the conditioning roles of technological progress and income level. The empirical evidence is based on a two-step system generalized method of moments (SYS-GMM) with forward orthogonal deviations for 42 countries in the SSA region from 2004 to 2018. The following results are established from the empirical analyses. First, renewable energy emerges as a promoter of environmental quality through its reducing impacts on carbon emissions per capita (co2pc). Second, other regressors turn out to impede environmental quality by contributing to the surge in co2pc. Third, the robustness checks analyses, which consider different variants of carbon emissions as outcome variables, revealing that the main results are robust and empirically supported to explain the variations in the level of pollutants in the region. Fourth, the impacts of technological progress from both direct (unconditional) and interactive (conditional) angles mitigate co2pc while income promotes it. On the policy front, promoting investment in renewable energy and structuring human capital development plans to promote green growth are seen as sacrosanct towards achieving a sustainable environment in the region

Effects of Exchange Correlation Functional (Vwdf3) on the Structural, Elastic, and Electronic Properties of Transition Metal Dichalogenides

In this research, the effects of Van der Waals forces on the structural, elastic, electronic, and optical properties of bulk transition metals dichalcogenides (TMDs) were studied using a novel exchange-correlation functional, vdW-DF3. This new functional tries to correct the hidden Van der Waals problems which are not reported by the previous exchange functionals. Molybdenum dichalcogenide, MoX 2 (X = S, Se, Te) was chosen as a representative transition metal dichalcogenide to compare the performance of the newly designed functional with the other two popular exchange-correlation functional; PBE and rVV10. From the results so far obtained, the analysis of the structural properties generally revealed better performance by vdW-DF3 via the provision of information on lattice parameters very closer to the experimental value. For example, the lattice constant obtained by vdW-DF3 was 3.161 Å which is very close to 3.163 Å and 3.160 Å experimental and theoretical values respectively. Calculations of the electronic properties revealed good performance by vdW-DF3 functional. Furthermore, new electronic features were revealed for MoX2 (X = S, Se, Te). In terms of optical properties, PBE functional demonstrates lower absorption than vdW-DF3, as such it can be reported that vdW-DF3 improves photon absorption by TMDs. However, our results also revealed that vdW-DF3 performed well for MoS2 than for MoSe2 and MoTe2 because of the lower density observed for the S atom in MoS2

Surgical site infection after gastrointestinal surgery in children : an international, multicentre, prospective cohort study

Introduction Surgical site infection (SSI) is one of the most common healthcare-associated infections (HAIs). However, there is a lack of data available about SSI in children worldwide, especially from low-income and middle-income countries. This study aimed to estimate the incidence of SSI in children and associations between SSI and morbidity across human development settings. Methods A multicentre, international, prospective, validated cohort study of children aged under 16 years undergoing clean-contaminated, contaminated or dirty gastrointestinal surgery. Any hospital in the world providing paediatric surgery was eligible to contribute data between January and July 2016. The primary outcome was the incidence of SSI by 30 days. Relationships between explanatory variables and SSI were examined using multilevel logistic regression. Countries were stratified into high development, middle development and low development groups using the United Nations Human Development Index (HDI). Results Of 1159 children across 181 hospitals in 51 countries, 523 (45 center dot 1%) children were from high HDI, 397 (34 center dot 2%) from middle HDI and 239 (20 center dot 6%) from low HDI countries. The 30-day SSI rate was 6.3% (33/523) in high HDI, 12 center dot 8% (51/397) in middle HDI and 24 center dot 7% (59/239) in low HDI countries. SSI was associated with higher incidence of 30-day mortality, intervention, organ-space infection and other HAIs, with the highest rates seen in low HDI countries. Median length of stay in patients who had an SSI was longer (7.0 days), compared with 3.0 days in patients who did not have an SSI. Use of laparoscopy was associated with significantly lower SSI rates, even after accounting for HDI. Conclusion The odds of SSI in children is nearly four times greater in low HDI compared with high HDI countries. Policies to reduce SSI should be prioritised as part of the wider global agenda.Peer reviewe