Search

We report a facile solution method to form titanium oxide (TiO2) nano-flower structure on the titanium (Ti) substrates for realizing good physical sterilization and biocompatibility. We first prepare TiO2nanotubes (NT) with a diameter of about 80–100 nm and a length of about 5 μm on Ti substrates by anodization, which is utilized as precursor. Then, we employ immersion treatment in different concentrations of phosphoric acid solution at 75 °C for 5 h to realize the transformation from TiO2NT to TiO2nano-flower structure. In addition, we studied the effects of phosphoric acid concentration (1 wt%, 2.5 wt%, 5 wt% and 10 wt%) on the TiO2nano-flower structure, and the antibacterial properties and biocompatibility of the TiO2nano-flower structure. The results show that TiO2nano-flower structure become larger and thicker with the increase in the phosphoric acid concentration, and the thickness of the coating can reach 6.88 μm. Meanwhile, the TiO2nano-flower structure shows good physical sterilization effect, especially for the TiO2nano-flower structure formed in 10 wt% H3PO4solution, the antibacterial rate can reach 95%. In addition, the TiO2nano-flower structure have no toxicity to the osteoblasts and support cell growth.

Understanding healthcare system resilience has become paramount, particularly in the wake of the COVID-19 pandemic, which imposed unprecedented burdens on healthcare services and severely impacted public health. Resilience is defined as the system’s ability to absorb, recover from and adapt to disruptions; however, despite extensive studies on this subject, we still lack empirical evidence and mathematical tools to quantify its adaptability (the ability of the system to adjust to and learn from disruptions). By analyzing millions of patients’ electronic medical records across US states, we find that the COVID-19 pandemic caused two successive waves of disruptions within the healthcare systems, enabling natural experiment analysis of the adaptive capacity of each system to adapt to past disruptions. We generalized the quantification framework and found that the US healthcare systems exhibit substantial adaptability (ρ= 0.58) but only a moderate level of resilience (r= 0.70). When considering system responses across racial groups, Black and Hispanic groups were more severely impacted by pandemic disruptions than white and Asian groups. Physician abundance was the key characteristic for determining healthcare system resilience. Our results offer vital guidance in designing resilient and sustainable healthcare systems to prepare for future waves of disruptions akin to COVID-19 pandemics.

Ti is regarded as one of the promising grain refiners in cast Al-Li-Cu alloys, but few research works have been done on its independent role. In this study, the effect of Ti on the microstructure evolution and mechanical properties of cast Al-2Li-2Cu-0.5Mg base alloy was investigated. The results revealed that the grains can be prominently refined with the increase of Ti addition. After adding Ti, high density TiB2-Al3Ti composite particles with a low lattice misfit form as heterogeneous nucleation sites for the α-Al matrix. δ′(Al3Li) and T1(Al2CuLi) precipitates that provide enhanced strength are dominated in the alloys after T6 aging treatment. The average size of both δ′ and half-width of δ′-precipitation free zone (PFZ) decreases gradually with the increase of Ti content. This is because the higher binding energy between Ti atoms and vacancies limits the diffusion efficiency of Li atoms, and thus results in a higher ductility. Additionally, no nano-sized Al3Ti or core-shell structure of Al3(Li, Ti) particles are found. The tensile property test results indicate that the Al-2Li-2Cu-0.5Mg alloy achieves optimal properties after aging at 175 °C for 32 h when 0.15wt.% Ti is added. It exhibits a yield strength of 352±5 MPa, an ultimate tensile strength of 423±6 MPa, and an elongation of (3±0.4)%. These findings are expected to offer a reliable theoretical guidance for the industrial composition design of the Al-Li-Cu series cast alloys.

Background The use of point-of-care testing (POCT) for influenza is not routine in many hospitals in the United Kngdom and testing is currently by laboratory-based polymerase chain reaction (PCR) tests. This review aims to evaluate patients who were tested positive for influenza in the last winter season and project if future POCT usage at initial point of patient assessment could assist in better utilisation of healthcare resources.Methods Retrospective review in a district general hospital without POCT facility for influenza. Medical records of patients who tested positive for influenza during a 4-month period from 1 October 2019 to 31 January 2020 in the paediatric department were reviewed and analysed.Results Thirty patients had laboratory-confirmed cases of influenza of which 63% (n= 19) were admitted to the ward. 56% of patients were not isolated at first instance on admission and 50% (n= 9) of admitted patients did not require inpatient management which totalled up to 224 h length of stay in ward.Conclusions Routine POCT for influenza can potentially improve management of patients presenting with respiratory symptoms and allocation of healthcare resources. We recommend its use to be introduced in diagnostic pathways for acute respiratory illness in the paediatric population in the next winter season in all hospitals.

The spatial spread of COVID-19 during early 2020 in China was primarily driven by outbound travelers leaving the epicenter, Wuhan, Hubei province. Existing studies focus on the influence of aggregated out-bound population flows originating from Wuhan; however, the impacts of different modes of transportation and the network structure of transportation systems on the early spread of COVID-19 in China are not well understood. Here, we assess the roles of the road, railway, and air transportation networks in driving the spatial spread of COVID-19 in China. We find that the short-range spread within Hubei province was dominated by ground traffic, notably, the railway transportation. In contrast, long-range spread to cities in other provinces was mediated by multiple factors, including a higher risk of case importation associated with air transportation and a larger outbreak size in hub cities located at the center of transportation networks. We further show that, although the dissemination of SARS-CoV-2 across countries and continents is determined by the worldwide air transportation network, the early geographic dispersal of COVID-19 within China is better predicted by the railway traffic. Given the recent emergence of multiple more transmissible variants of SARS-CoV-2, our findings can support a better assessment of the spread risk of those variants and improve future pandemic preparedness and responses.

We describe a P-containing palladacycle-catalyzed regioselective Heck reaction of 2,3-dihydrofuran with diaryliodonium salts and aryl iodides to afford 2-aryl-2,5-dihydrofurans and 2-aryl-2,3-dihydrofurans, respectively, in good yields. Mechanistic studies revealed that the oxidative addition of diaryliodonium salts to palladacycles to form Pd(IV) species showed high chemoselectivity and that electron-rich aryl moieties were preferentially transferred to the Heck product. DFT calculations indicated that the regioselectivity-determining step is the reductive elimination reaction rather than the isomerization and reinsertion of Pd(IV)–hydride intermediates into the double bond.

The normal gravity model of a hypersonic boost-glide vehicle in near space is studied in this paper with the aim of alleviating the influence of the gravity model error on the precision of the inertial navigation system (INS) during flight. First, a spherical harmonic model of the Earth’s gravitational field is introduced and the normal gravity of the Earth is derived from it. Then, the coordinate transformation needed for the application of the gravity model to the near-space navigation algorithm is formulated. Subsequently, the gravity disturbance in near space and the impact of J2and J4gravity truncation errors are analyzed. Finally, different normal gravity models and different precisions of inertial measurement unit (IMU) are exploited to simulate the near-space navigation algorithm. Based on this, the influence of the independent and combined effects caused by the interference factors is analyzed, and the applicable conditions of the normal gravity model are discussed.

We investigate the second-order optical response of graphene irradiated by two-color lights with frequencies ω and 3ω, focusing on the modulation by ellipticity and phase of the incident fields. Based on the analytical perturbation theory, it is found that the interplay between the second harmonic generation (SHG) (ω+ω) and difference frequency generation (DFG) (3ω−ω) processes leads to nontrivial nonlinear optical properties. The interference between the two processes (SHG and DFG) results in different dependencies of the second-order response intensity I(2ω) on ellipticity, including monotonic, nonmonotonic change of I(2ω) with ellipticity, or even nearly independent of ellipticity under suitable conditions. The optimal incident angles for the highest I(2ω) are found, which can be tuned by changing the ellipticity, relative phase, or field strength of the incident light. In particular, a large output enhancement with respect to a small increment of the incident field can be achieved. We have found effective methods of modulating nonlinear optical processes, which may have applications in optical devices based on two-dimensional materials.

A scalable enantioselective nickel-catalyzed electrochemical reductive homocoupling of aryl bromides has been developed, affording enantioenriched axially chiral biaryls in good yield under mild conditions using electricity as a reductant in an undivided cell. Common metal reductants such as Mn or Zn powder resulted in significantly lower yields in the absence of electric current under otherwise identical conditions, underscoring the enhanced reactivity provided by the combination of transition metal catalysis and electrochemistry.

The middle Jurassic Zhiluo Formation in the Dongsheng is comprised of a big set of green sandstone/mudstone with most of uranium orebodies occurring in close proximity to its footwall. By synthesizing field observations, region analysis, data collected from previous coal and uranium borehole, a regional north-south geological profile across the entire orefield is conducted. Experiments on sandstone/mudstone including rock mineral identification, clastic micromorphology and element geochemistry were carried out. Information from the geological profile indicates that green sandstone/mudstone is widely present in a stable horizon with clear boundaries to the country rock. Microscopic observations and geochemical data on sandstone/mudstone exhibit similar mineral composition with almost identical slightly flat, minor Eu enriched, Ce depleted chondrite-normalized REE patterns. Furthermore, the green clay membrane of the clasts has a complex composition containing chlorite/smectite, green smectite, chlorite, and green kaolinite, with elements including Fe, Mg, Si, and Al. These above results indicate that the green sandstone/mudstone underwent resemble sedimentary diagenetic processes as the country rock without transformation by large-scale regional fluid, while the existence of Fe2+-rich membrane is the main factor to the green sandstone/mudstone. Further concentration of the pre-enrichment uranium during diagenetic process led to the final formation for uranium deposits. The above studies are conducive to enrich the metallogenic mechanism of sandstone type uranium deposits and could provide certain reference for uranium exploration and deployment.

Our previous studies showed that the combination of atorvastatin (ATV) and single injection of ATV‐pretreated mesenchymal stem cells (MSCs) (ATV‐MSCs) at 1 week post‐acute myocardial infarction (AMI) promoted MSC recruitment and survival. This study aimed to investigate whether the combinatorial therapy of intensive ATV with multiple injections of ATV‐MSCs has greater efficacy at different stages to better define the optimal strategy for MSC therapy in AMI. In order to determine the optimal time window for MSC treatment, we first assessed stromal cell‐derived factor‐1 (SDF‐1) dynamic expression and inflammation. Next, we compared MSC recruitment and differentiation, cardiac function, infarct size, and angiogenesis among animal groups with single, dual, and triple injections of ATV‐MSCs at early (Early1, Early2, Early3), mid‐term (Mid1, Mid2, Mid3), and late (Late1, Late2, Late3) stages. Compared with AMI control, intensive ATV significantly augmented SDF‐1 expression 1.5∼2.6‐fold in peri‐infarcted region with inhibited inflammation. ATV‐MSCs implantation with ATV administration further enhanced MSC recruitment rate by 3.9%∼24.0%, improved left ventricular ejection fraction (LVEF) by 2.0%∼16.2%, and reduced infarct size in all groups 6 weeks post‐AMI with most prominent improvement in mid groups and still effective in late groups. Mechanistically, ATV‐MSCs remarkably suppressed inflammation and apoptosis while increasing angiogenesis. Furthermore, triple injections of ATV‐MSCs were much more effective than single administration during early and mid‐term stages of AMI with the best effects in Mid3 group. We conclude that the optimal strategy is multiple injections of ATV‐MSCs combined with intensive ATV administration at mid‐term stage of AMI. The translational potential of this strategy is clinically promising. Stem Cells Translational Medicine2019;8:1068–1083 Our study first revealed that intensive atorvastatin (ATV) treatment dramatically augmented the SDF‐1 expression in peri‐infarcted myocardium over the entire period of AMI with simultaneous inhibiting the inflammation. The optimal strategy for further improving the efficacy of mesenchymal stem cells (MSCs) therapy was at least triple intravenous administrations of ATV‐pretreated MSCs in mid‐term stage of AMI combined with intensive ATV treatment. The underlying mechanisms mainly attributed to the marked enhancement of ATV‐MSCs recruitment and survival, angiogenesis in the infarcted region instead of myocardium regeneration.

Virus-induced gene silencing (VIGS) showed several advantages to identify gene functions such as short experimental cycle, more broad hosts, etc. In this study, the feasibility and efficiency of employing Barley stripe mosaic virus(BSMV)-based VIGS system to evaluate Fusarium head blight (FHB) resistance were explored in wheat. With variable conditions tested, it showed that the maximal silencing efficiency 78% on spike was obtained when the recombinant BSMV was inoculated on flag leaf at flagging stage. However, the plant may reduce its own immunity to FHB when inoculated with BSMV. To induce this impact, different Fusarium graminearumstrains were tested and SF06-1 strain was selected for FHB resistance evaluation. Using this system, TaAOC, TaAOS,and TaOPR3involved in jasmonic acid (JA) signaling pathway were identified to positively regulate FHB resistance, which was underpinned by the results when silencing TaAOSin wheat by stable transgenic plants.

The mutation of the gene encoding a stearoyl-acyl carrier protein fatty acid desaturase (ssi2) has been proved to enhance pathogen resistance in several plants, while it's potential to regulate biotic and abiotic stresses in wheat is still unclear. In this study, we cloned TaSSI2gene in wheat and provided several evidences of its involvement in multiple biological functions. By using barley stripe mosaic virus (BSMV)-induced gene silencing (VIGS) in wheat, it was found that TaSSI2negatively regulated both powdery mildew and Fusarium head blight (FHB) resistance, which was consistent with the phenotype observed in knock-out mutants of Kronos. The expression of TaSSI2was down-regulated by in vitrotreatments of methyl jasmonate (MeJA), but positively regulated by salicylic acid (SA) and abscisic acid (ABA), implying the cross-talk between different hormone signaling pathways involved in wheat to regulate biotic stresses is still to be elucidated. Furthermore, the up-regulated expression of PR4and PR5indicated that TaSSI2probably regulated FHB resistance by depressing the SA signaling pathway in wheat. In addition, the over-expression of TaSSI2increased the content of linolenic acid (18:3) and subsequently enhanced drought tolerance of transgenic Brachypodium.This phenomenon might be associated with its subcellular localization in the whole cytosol, partly overlapping with Golgi apparatus and the secreted vesicles. As a stearoyl-acyl carrier protein fatty acid desaturase, TaSSI2was proposed to be involved in cell lipid metabolism and carried targets out of the cell from membrane or wax synthesis, resulting in enhanced drought tolerance in plant.

The equivalence of regularity of a Q -matrix with its bounded perturbations is proved and an integration by parts formula is established for the associated Feller minimal transition functions. [ABSTRACT FROM AUTHOR]

The COVID-19 Scenario Modeling Hub convened nine modeling teams to project the impact of expanding SARS-CoV-2 vaccination to children aged 5–11 years on COVID-19 burden and resilience against variant strains.

We investigate the effects of the frequency-degree correlation on local synchronization in complex networks with Kuramoto oscillators. We find that a discontinuous synchronization transition occurs in the local patterns for heterogenous networks while for homogenous networks, the local synchronization transition remains continuous. Then, we extend our study to a general frequency-degree correlation case and conclude that the positive correlation does not change the local synchronization patterns while in the case of a negative correlation, the local synchronization transition degenerates to second order. Moreover, the correlation parameter αis verified to have a strong influence on the synchronization level. In particular, smaller |α| results in higher synchronization ability and faster speed to a synchronized state. Our study provides a deeper understanding of the effects of the frequency-degree correlation on network synchronization.

The voter model has served to address the emergence of consensus within populations of individuals. However, the dynamics based on the classic voter model has usually been analyzed based on the assumption that the two states in the model are simply equivalent. In this paper, we discuss a mathematical description of the weighted voter model and obtain a series of results for the evolutionary process on complex networks. For homogeneous networks, we study the active link density analytically and find that the opinion strength plays a crucial role in determining whether the system can reach consensus. We also extend our research to heterogeneous networks and discover that the network structure can affect the convergence time but has less influence on the positive proportion. The results can be applied to various pervasive cases in which two conflicting opinions interact with each other.

The immunization strategy to halt virus is an important topic in epidemic spreading research. In this paper, we extend our seasonal epidemics immunization model on correlated networks. We apply numerical results of our model on different kinds of networks. We first investigate the relationship between epidemic prevalence and epidemic season. We find that the immunization performs best on negative correlated network, and give an explanation. We also present the result of epidemic prevalence with different vaccinating proportion and epidemic spreading probability.

The quantification of complexity is one of the most fundamental issues in the investigation of complex networks. In this paper, we propose multi-states entropy to quantify the complexity of a typical diffusion system, in which the interactive dynamics is characterized by a finite capacity effect. We show that the entropy strongly depend on the local topology and the finite capacity. Furthermore, based on the maximum entropy principle, we optimize the interaction of these two factors to achieve the most efficient interactive diffusion process on scale-free networks.

The study of intentional attackshas become an important issue onthe research of complex networks. In this paper, we study the resilience of networks, introducing the parameters that describe the attacks effect and the parameters that measure the priority of intentional attacks. Weestablish analgorithm to analysis the intentional attack phenomenon and present the numerical simulation.

Abstract: The Koszul-like property for any finitely generated graded modules over a Koszul-like algebra is investigated and the notion of weakly Koszul-like module is introduced. We show that a finitely generated graded module M is a weakly Koszul-like module if and only if it can be approximated by Koszul-like graded submodules, which is equivalent to the fact that G(M) is a Koszul-like module, where G(M) denotes the associated graded module of M. As applications, the relationships between minimal graded projective resolutions of M and G(M), and Koszul-like submodules are established. Moreover, the Koszul dual of a weakly Koszul-like module is proved to be generated in degree 0 as a graded E(A)-module.

Recently, response problems of extant structures under dynamic loads have been hot spots with the increase of earthquake disasters. Dynamic response analyses of underground rock tunnel have been made using the dynamic mode of 3D finite difference software FLAC3D, considering the impacts of different lateral pressure coefficients on the rock tunnel under the same earthquake load. Some conclusions are drawn: the vertical displacement of the bottom of rock tunnel arch is the maximum under the same earthquake load; the maximum vertical displacement at the tunnel top decreases with the increase of lateral pressure coefficient; the maximum vertical velocity at the tunnel shoulder increases with the lateral pressure coefficient; the maximum vertical acceleration at the tunnel bottom first increases and then decreases with the lateral pressure coefficient.

In this paper, small strain model, being able to reflect the small strain characteristics of soil, was adopted to calculate and analyze surface deformation caused by shield tunnel construction. Under the single tunneling, the maximum surface settlement is generally just above the tunnel axis, and surface settlement is symmetric distribution on both sides of the tunnel axis, and decreases with the increase of the horizontal distance; the longitudinal surface settlement is "tilted S-shaped" curve, and tends to basically stabilize at a certain position behind the excavation face; The comprehensive comparison shows better consistency between the data from small strain model and those from actual measure, and then verifies the feasibility and effectiveness of the small strain model applied for surface deformation analysis caused by urban metro shield construction.

For a healthy environment for hot spring recreation, this study discussed the diffusion in the bathroom of hydrogen sulfide gas from hot sulfur springs for an improvement of this harmful situation. Based on empirical measurements and then comparing the results with CFD simulation, the analysis exposed the distribution status of indoor hydrogen sulfide and its diffusion behavior. Results indicate that sulfur springs produce high levels of hydrogen sulfide that are hazardous. And the high concentrations can be improved under ideal ventilation, which was determined by the air exchange rate, flow field efficiency, turbulence and vortex phenomena.

800x600 Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman","serif";} The strip replacement mining in short-distance thin coal seam is one of the effective methods controlling displacement deformation of overlying strata and surface subsidence in coal mining under buildings and railroads and water bodies. The method has a great theoretical significance and application value by increasing recovery rate of coal resources and cutting down the effect of coal mining on environment and surface of mining area. The numerical simulation method is adopted to study the surface deformation characteristics by the strip replacement mining in short-distance thin coal seam. Such conclusions are drawn as follows: the strip project of forty meters mining with forty meters reserving is quite suitably selected while half of mining rate; ten meters in replacement width of coal pillar is relatively optimum; the feasibility of the strip replacement mining technology is verified by the simulation. Therefore, the strip replacement mining technology has provided one kind of new thought to coal mining under buildings and railroads and water bodies.

The thermal degradation of natural rubber (NR) in air at a constant heating rate was studied by using of the thermogravimetry (TG) and thermogravimetry and differential thermal analysis (TG–DTA) simultaneous techniques. It indicates that the temperature of thermal degradation of gel and sol of NR rises linearly along with the increment of the heating rate, whereas the heating rate has little effect on the degree of thermal degradation. Accompanying other side reactions, the thermal degradation of NR is not a simple random chain scission process, and it is an exothermic reaction. The dynamic variation of molecular structure of NR during the thermal degradation was studied using Fourier transform infrared spectroscopy (FTIR). It shows that the products of the thermal degradation of both sol and gel of NR are hydroperoxide, carbonyl, and hydroxyl compounds. The formation of gel makes the temperature of the thermal degradation of NR decrease and the rate of the thermal degradation increase; thus, the thermal stability of NR is reduced. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1339–1344, 2000

The dynamic variations of molecular structure and properties of natural rubber (NR) during the accelerated storage have been studied. The results showed that, with the prolonging of the storage time, the average molecular weight and the gel content increased, the width index of molecular weight distribution decreased, the gel size increased gradually, but the crosslinking density of gel fluctuated only within a narrow range. Besides, the initial plasticity increased, whereas the plasticity retention index decreased. The studies with thermal analyses and infrared spectroscopy showed that the thermal degradation temperature dropped, the thermal degradation rate increased, and the thermal stability has decreased after the storage of NR. The molecular structure and properties of NR are in a state of dynamic variation during accelerate storage. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 1779–1783, 1998

The thermal degradation and thermooxidative degradation of epoxidized natural rubber (ENR) were studied by thermogravimetry (TG). In the thermal degradation of ENR, the initial temperature of weight loss T0 = 1.20B + 348, the temperature of maximum weight loss rate Tp = 1.07B + 392, and the final temperature of weight loss Tf = 0.77B + 445. The Cp, which corresponds to the degradation rate at temperature Tp, increases along with the heating rate B and its mean value is 43%, but Cf, which corresponds to the degradation rate at temperature Tf, is not affected by the heating rate, and its average value is close to 100%. As in the thermooxidative degradation, T0 = 1.84B + 246, Tp = 0.30B + 378, and Tf = 2.27B + 584. The value of Cp increases along with the heating rate B and its mean value is 36%, but Cf is not affected by the heating rate and the average value approximately equals 100%. The thermal degradation in nitrogen could be a one-step reaction, whereas the thermooxidative degradation has a multiple-step reaction. The reactive environment has a great effect on the thermal degradation of ENR and the difference of the mechanisms of the two reaction systems is obvious. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:2207–2211, 1998

An electrochemical asymmetric coupling of secondary acyclic amines with ketones via a Shono-type oxidation has been described, affording the corresponding amino acid derivatives with good to excellent diastereoselectivity and enantioselectivity. The addition of an N-oxyl radical as a redox mediator could selectively oxidize the substrate rather than the product, although their oxidation potential difference is subtle (about 13 mV). This electrochemical transformation proceeds in the absence of stoichiometric additives, including metals, oxidants, and electrolytes, which gives it good functional group compatibility. Mechanistic studies suggest that proton-mediated racemization of the product is prevented by the reduction of protons at the cathode.

Percutaneous Endoscopic Gastrostomy (PEG) is increasingly being used in the pediatric population. We report a case of a 5-year-old boy who is fully PEG-fed that presented with a 2-day history of vomiting and diarrhea. His vomiting resolved however, the diarrhea remained persistent and watery with occasional undigested milk. His blood and stool investigation results were unremarkable however contrast study through the gastrostomy revealed migration of tube into the transverse colon. Laparoscopy was then performed for fistula resection and a new gastrostomy tube was inserted. Gastrostomy tube migration in children is not well-documented and this complication should be thought about when pediatricians are presented with a case of refractory diarrhea in PEG-fed patients.

Dengue is a vector-borne disease transmitted by the Aedesgenus mosquito. It causes financial burdens on public health systems and considerable morbidity and mortality. Tropical regions in the Americas and Asia are the areas most affected by the virus. Fortaleza is a city with approximately 2.6 million inhabitants in northeastern Brazil that, during the recent decades, has been suffering from endemic dengue transmission, interspersed with larger epidemics. The objective of this paper is to study the impact of human mobility in urban areas on the spread of the dengue virus, and to test whether human mobility data can be used to improve predictions of dengue virus transmission at the neighbourhood level. We present two distinct forecasting systems for dengue transmission in Fortaleza: the first using artificial neural network methods and the second developed using a mechanistic model of disease transmission. We then present enhanced versions of the two forecasting systems that incorporate bus transportation data cataloguing movement among 119 neighbourhoods in Fortaleza. Each forecasting system was used to perform retrospective forecasts for historical dengue outbreaks from 2007 to 2015. Results show that both artificial neural networks and mechanistic models can accurately forecast dengue cases, and that the inclusion of human mobility data substantially improves the performance of both forecasting systems. While the mechanistic models perform better in capturing seasons with large-scale outbreaks, the neural networks more accurately forecast outbreak peak timing, peak intensity and annual dengue time series. These results have two practical implications: they support the creation of public policies from the use of the models created here to combat the disease and help to understand the impact of urban mobility on the epidemic in large cities.

Consider a non-explosive positive Feller process with no negative jumps. It is shown in this note that when infinity is an entrance boundary, in the sense that the entrance times of the process remain bounded when the initial value tends to infinity, the process admits a Feller extension on the compactified state space [ 0 , ∞ ]. Moreover, when started from infinity, the extended Markov process on [ 0 , ∞ ] leaves infinity instantaneously and stays finite, almost-surely. Arguments are adapted from a proof given by Kallenberg (2002) for diffusions. We also show that the process started from x converges weakly towards that started from infinity in the Skorokhod space, when x goes to infinity. [ABSTRACT FROM AUTHOR]

A variety of mechanistic and statistical methods to forecast seasonal influenza have been proposed and are in use; however, the effects of various data issues and design choices (statistical versus mechanistic methods, for example) on the accuracy of these approaches have not been thoroughly assessed. Here, we compare the accuracy of three forecasting approaches—a mechanistic method, a weighted average of two statistical methods and a super-ensemble of eight statistical and mechanistic models—in predicting seven outbreak characteristics of seasonal influenza during the 2016–2017 season at the national and 10 regional levels in the USA. For each of these approaches, we report the effects of real time under- and over-reporting in surveillance systems, use of non-surveillance proxies of influenza activity and manual override of model predictions on forecast quality. Our results suggest that a meta-ensemble of statistical and mechanistic methods has better overall accuracy than the individual methods. Supplementing surveillance data with proxy estimates generally improves the quality of forecasts and transient reporting errors degrade the performance of all three approaches considerably. The improvement in quality from ad hoc and post-forecast changes suggests that domain experts continue to possess information that is not being sufficiently captured by current forecasting approaches.

Supplemental Digital Content is available in the text