Allee effect that refers to a positive relationship between individual fitness and population density provides an important conceptual framework in conservation biology. While declining Allee effect ...causes reduction in extinction risk in low-density population, it provides a benefit in limiting establishment success or spread of invading species. Population models that incorporated Allee effect confer the fundamental role which plays for shaping the population dynamics. In particular, non-spatial predator–prey and invasion models have shown the influence of Allee effects on population dynamics, and spatial models have illustrated its critical roles for pattern formation and the manifestation of traveling wave fronts. We highlight all such no-spatial and spatial population models and their contributions in deeper understanding of population dynamics. In addition, we briefly outline the trends for future research on Allee effect which we think are interesting and widely open.
One subject of spatial epidemiology is spatial variation in disease risk or incidence. The spread of epidemics can result in strong spatial patterns of such risk or incidence: for example, pathogen ...dispersal might be highly localized, vectors or reservoirs for pathogens might be spatially restricted, or susceptible hosts might be clumped. Here, spatial pattern of an epidemic model with nonlinear incidence rates is investigated. The conditions for Hopf bifurcation and Turing bifurcation are gained and, in particular, exact Turing domain is found in the two parameters space. Furthermore, numerical results show that force of infection, namely
β
, plays an important role in the spatial pattern. More specifically, different patterns emerge as
β
increases. The mathematical analysis and numerical results well extend the finding of pattern formation in the epidemic models and may well explain the field observed in some areas.
Abstract
Electrochemical catalytic reductive cross couplings are powerful and sustainable methods to construct C−C bonds by using electron as the clean reductant. However, activated substrates are ...used in most cases. Herein, we report a general and practical electro-reductive Ni-catalytic system, realizing the electrocatalytic carboxylation of unactivated aryl chlorides and alkyl bromides with CO
2
. A variety of unactivated aryl bromides, iodides and sulfonates can also undergo such a reaction smoothly. Notably, we also realize the catalytic electrochemical carboxylation of aryl (pseudo)halides with CO
2
avoiding the use of sacrificial electrodes. Moreover, this sustainable and economic strategy with electron as the clean reductant features mild conditions, inexpensive catalyst, safe and cheap electrodes, good functional group tolerance and broad substrate scope. Mechanistic investigations indicate that the reaction might proceed via oxidative addition of aryl halides to Ni(0) complex, the reduction of aryl-Ni(II) adduct to the Ni(I) species and following carboxylation with CO
2
.
Anus preservation has been a challenge in the treatment of patients with low rectal adenocarcinoma (within 5 cm from the anal verge) because it is difficult to spare the anus with its functioning ...sphincter complex under the safe margin of tumour resection. Patients with dMMR/MSI-H can achieve a favourable complete response (CR) rate by using a single immune checkpoint inhibitor. For patients with pMMR/MSS/MSI-L, intensified neoadjuvant three-drug chemotherapy may be the preferred option for anal preservation. In addition, the watch and wait (W&W) strategy has been proven safe and feasible for patients with rectal cancer who achieve a clinical complete response (cCR). Therefore, we initiated this clinical trial to explore the optimal neoadjuvant treatment pattern for patients with low locally advanced rectal cancer (LARC) with different MMR/MSI statuses, aiming to achieve a higher cCR rate with the W&W strategy and ultimately provide more patients with a chance of anus preservation.
This is a randomised, controlled, open-label, multicentre phase III trial. Patients with clinical stage T2-4 and/or N + tumours located within 5 cm from the anal verge are considered eligible. Based on the results of pathological biopsy, the patients are divided into two groups: dMMR/MSI-H and pMMR/MSS. Patients in the dMMR/MSI-H group will be randomly allocated in a 1:1 ratio to either arm A (monoimmunotherapy) or arm B (short-course radiotherapy followed by monoimmunotherapy). Patients in the pMMR/MSS group will be initially treated with long-term pelvic radiation with concurrent capecitabine combined with irinotecan. Two weeks after the completion of chemoradiotherapy (CRT), the patients will be randomly allocated in a 1:1 ratio to arm C (XELIRI six cycle regime) or arm D (FOLFIRINOX nine cycle regime). The irinotecan dose will be adjusted according to the UGT1A1-genotype. After treatment, a comprehensive assessment will be performed to determine whether a cCR has been achieved. If achieved, the W&W strategy will be adopted; otherwise, total mesorectal excision (TME) will be performed. The primary endpoint is cCR with the maintenance of 12 months at least, determined using digital rectal examination, endoscopy, and rectal MRI or PET/CT as a supplementary method.
APRAM will explore the best anus preservation model for low LARC, combining the strategies of consolidation chemotherapy, immunotherapy, and short-course radiotherapy, and aims to preserve the anus of more patients using W&W. Our study provides an accurate individual treatment mode based on the MMR/MSI status for patients with low LARC, and more patients will receive the opportunity for anus preservation under our therapeutic strategy, which would transform into long-term benefits.
Clinicaltrials.gov NCT05669092 (Registered 28th Nov 2022).
With the development of information technology, Internet-of-Things (IoT) and low-altitude remote-sensing technology represented by Unmanned Aerial Vehicles (UAVs) are widely used in environmental ...monitoring fields. In agricultural modernization, IoT and UAV can monitor the incidence of crop diseases and pests from the ground micro and air macro perspectives, respectively. IoT technology can collect real-time weather parameters of the crop growth by means of numerous inexpensive sensor nodes. While depending on spectral camera technology, UAVs can capture the images of farmland, and these images can be utilize for analyzing the occurrence of pests and diseases of crops. In this work, we attempt to design an agriculture framework for providing profound insights into the specific relationship between the occurrence of pests/diseases and weather parameters. Firstly, considering that most farms are usually located in remote areas and far away from infrastructure, making it hard to deploy agricultural IoT devices due to limited energy supplement, a sun tracker device is designed to adjust the angle automatically between the solar panel and the sunlight for improving the energy-harvesting rate. Secondly, for resolving the problem of short flight time of UAV, a flight mode is introduced to ensure the maximum utilization of wind force and prolong the fight time. Thirdly, the images captured by UAV are transmitted to the cloud data center for analyzing the degree of damage of pests and diseases based on spectrum analysis technology. Finally, the agriculture framework is deployed in the Yangtze River Zone of China and the results demonstrate that wheat is susceptible to disease when the temperature is between 14 °C and 16 °C, and high rainfall decreases the spread of wheat powdery mildew.
Chemical doping is often used to enhance electric conductivity of the conjugated molecule as hole‐transporting material (HTM) for the application in optoelectronics. However, chemical dopants can ...promote ion migration at the electrical field, which deteriorates the device efficiency as well as increases the fabrication cost. Here, two star HTMs, namely 2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxyphenyl‐amine) 9,9′‐spirobifluorene (Spiro‐OMeTAD) and poly(triarylamine) are subjeted to chemical combination to yield dopant‐free N2,N2,N2′,N2′,N7,N7,N7′,N7′‐octakis(4‐methoxyphenyl)‐10‐phenyl‐10H‐spiroacridine‐9,9′‐fluorene‐2,2′,7,7′‐tetraamine (SAF‐OMe). The power conversion efficiencies (PCEs) of 12.39% achieved by solar cells based on pristine, dopant‐free SAF‐OMe are among the highest reported for perovskite solar cells and are even comparable to devices based on chemically doped Spiro‐OMeTAD (14.84%). Moreover, using a HTM comprised of SAF‐OMe with an additional dopant results in a record PCE of 16.73%. Compared to Spiro‐OMeTAD‐based devices, SAF‐OMe significantly improves stability.
A dopant‐free hole‐transporting material (HTM), N2,N2,N2′,N2′,N7,N7,N7′,N7′‐octakis(4‐methoxyphenyl)‐10‐phenyl‐10H‐spiroacridine‐9,9′‐fluorene‐2,2′,7,7′‐tetraamine (SAF‐OMe), is developed and implemented for use in perovskite solar cells. The power conversion efficiency (PCE) achieved by using SAF‐OMe as HTM is 12.39%, more than two times the reference 2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxyphenyl‐amine)9,9′‐spirobifluorene (Spiro‐OMeTAD).
•P. tolaasii Y-11 has excellent heterotrophic nitrifying–aerobic denitrifying ability.•High removal rates of inorganic nitrogen without nitrite accumulation at 15°C.•It tolerates to high ...concentrations of ammonium, nitrate and nitrite nitrogen.•It could effectually remove NH4+ in simultaneous nitrification and denitrification.
A hypothermia aerobic nitrite-denitrifying bacterium, Pseudomonas tolaasii strain Y-11, was found to display high removal capabilities for heterotrophic nitrification with ammonium and for aerobic denitrification with nitrate or nitrite nitrogen. When strain Y-11 was cultivated for 4days at 15°C with the initial ammonium, nitrate and nitrite nitrogen concentrations of 209.62, 204.61 and 204.33mg/L (pH 7.2), the ammonium, nitrate and nitrite removal efficiencies were 93.6%, 93.5% and 81.9% without nitrite accumulation, and the corresponding removal rates reached as high as 2.04, 1.99 and 1.74mg/L/h, respectively. Additionally, ammonium was removed mainly during the simultaneous nitrification and denitrification process. All results demonstrate that P. tolaasii strain Y-11 has the particularity to remove ammonium, nitrate and nitrite nitrogen at low temperatures, which guarantees it for future application in winter wastewater treatment.
Strong coupling between plasmons and optical modes, such as waveguide or resonator modes, gives rise to a splitting in the plasmon absorption band. As a result, two new hybrid modes are formed that ...exhibit near-field enhancement effects. These hybrid modes have been exploited to improve light absorption in a number of systems. Here we show that this modal strong coupling between a Fabry-Pérot nanocavity mode and a localized surface plasmon resonance (LSPR) facilitates water splitting reactions. We use a gold nanoparticle (Au-NP)/TiO
/Au-film structure as a photoanode. This structure exhibits modal strong coupling between the Fabry-Pérot nanocavity modes of the TiO
thin film/Au film and LSPR of the Au NPs. Electronic excitation of the Au NPs is promoted by the optical hybrid modes across a broad range of wavelengths, followed by a hot electron transfer to TiO
. A key feature of our structure is that the Au NPs are partially inlaid in the TiO
layer, which results in an enhancement of the coupling strength and water-oxidation efficiency. We observe an 11-fold increase in the incident photon-to-current conversion efficiency with respect to a photoanode structure with no Au film. Also, the internal quantum efficiency is enhanced 1.5 times under a strong coupling over that under uncoupled conditions.
In this paper, we present a novel meta-feature generation method in the context of meta-learning, which is based on rules that compare the performance of individual base learners in a one-against-one ...manner. In addition to these new meta-features, we also introduce a new meta-learner called Approximate Ranking Tree Forests (ART Forests) that performs very competitively when compared with several state-of-the-art meta-learners. Our experimental results are based on a large collection of datasets and show that the proposed new techniques can improve the overall performance of meta-learning for algorithm ranking significantly. A key point in our approach is that each performance figure of any base learner for any specific dataset is generated by optimising the parameters of the base learner separately for each dataset.
Spatial patterns are ubiquitous in nature, which have been identified as important factors in dynamics of ecosystems. However, how pattern structures have influence on persistence of populations is ...far from well being understood. Particularly, whether some characters of spatial pattern can be indicators for ecosystems collapse is not well studied. As a result, we presented a predator–prey system with spatial motion and found that isolation degree (average distance between patterns with high density) of spatial patterns plays an important role in the persistence of populations: If isolation degree is much smaller, then the population will persist; if isolation degree is much larger, then the population density will decrease with increasing space size and run a high risk of extinction as space size is large enough. Our results highlight the relationship between pattern structures and ecosystems collapse.
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