Distribution Of Patches Research Articles

Exogenous disturbances and endogenous self‐organized processes are not mutually exclusive drivers of spatial patterns in macroalgal assemblages

Complex spatial patterns are common in coastal marine systems, but mechanisms underlying their formation are disputed. Most empirical work has focused on exogenous spatially structured disturbances as the leading cause of pattern formation in species assemblages. However, theoretical and observational studies suggest that complex spatial patterns, such as power laws in gap‐size distribution, may result from endogenous self‐organized processes involving local‐scale interactions. The lack of studies simultaneously assessing the influence of spatially variable disturbances and local‐scale interactions has fuelled the idea that exogenous and endogenous processes are mutually exclusive explanations of spatial patterns in marine ecosystems. To assess the relative contribution of endogenous and exogenous processes in the emergence of spatial patterns, an intertidal assemblage of algae was exposed for two years to various combinations of intensity and spatial patterns of disturbance. Localized disturbances impinging at the margins of previously disturbed clearings and homogenous disturbances without any spatial pattern generated heterogeneous distributions of disturbed gaps and macroalgal patches, characterized by a power‐law scaling. Spatially varying disturbances produced a spatial gradient in the distribution of algal patches and, to a lesser extent, also a power‐law scaling in both patch‐ and gap‐size distributions. These results suggest that exogenous and endogenous processes are not mutually exclusive forces that can lead to the formation of similar spatial patterns in species assemblages.

Extended Gassmann equation with dynamic volumetric strain: Modeling wave dispersion and attenuation of heterogeneous porous rocks

Sedimentary rocks are often heterogeneous porous media inherently containing complex distributions of heterogeneities (e.g., fluid patches and cracks). Understanding and modeling their frequency-dependent elastic and adsorption behaviors is of great interest for subsurface rock characterization from multiscale geophysical measurements. The physical parameter of dynamic volumetric strain (DVS) associated with wave-induced fluid flow is proposed to understand the common physics and connections behind known poroelastic models for modeling dispersion behaviors of heterogeneous rocks. We have derived the theoretical formulations of DVS for patchy saturated rock at the mesoscopic scale and cracked porous rock at microscopic grain scales, essentially embodying the wave-induced fluid-pressure relaxation process. By incorporating DVS into the classic Gassmann equation, a simple but practical “dynamic equivalent” modeling approach, the extended Gassmann equation, is developed to characterize the dispersion and attenuation of complex heterogeneous rocks at nonzero frequencies. Using the extended Gassmann equation, the effect of microscopic or mesoscopic heterogeneities with complex distributions on the wave dispersion and attenuation signatures can be captured. Our theoretical framework provides a simple and straightforward analytical methodology to calculate wave dispersion and attenuation in porous rocks with multiple sets of heterogeneities exhibiting complex characteristics. We also demonstrate that, with the appropriate consideration of multiple crack sets and complex fluid patches distribution, the modeling results can better interpret the experimental data sets of dispersion and attenuation for heterogeneous porous rocks.

High spatial resolution mapping identifies habitat characteristics of the invasive vine Antigonon leptopus on St. Eustatius (Lesser Antilles)

AbstractOn the Caribbean island of St. Eustatius, Coralita (Antigonon leptopus) is an aggressive invasive vine posing major biodiversity conservation concerns. The generation of distribution maps can address these conservation concerns by helping to elucidate the drivers of invasion. We test the use of support vector machines to map the distribution of Coralita on St. Eustatius at high spatial resolution and use this map to identify potential landscape and geomorphological factors associated with Coralita presence. This latter step was performed by comparing the actual distribution of Coralita patches to a random distribution of patches. To train the support vector machine algorithm, we used three vegetation indices and seven texture metrics derived from a 2014 WorldView‐2 image. The resulting map shows that Coralita covered 3.18% of the island in 2014, corresponding to an area of 64 ha. The mapped distribution was highly accurate, with 93.2% overall accuracy (Coralita class producer's accuracy: 76.4%, user's accuracy: 86.2%). Using this classification map, we found that Coralita is not randomly distributed across the landscape, occurring significantly closer to roads and drainage channels, in areas with higher accumulated moisture, and on flatter slopes. Coralita was found more often than expected in grasslands, disturbed forest, and urban areas but was relatively rare in natural forest. These results highlight the ability of high spatial resolution data from sensors such as WorldView‐2 to produce accurate invasive species, providing valuable information for predicting current and future spread risks and for early detection and removal plans.Abstract in Dutch is available with online material.

Monitoring of the Fire in Muli County on March 28, 2020, based on high temporal-spatial resolution remote sensing techniques

Wildfires are serious natural disasters, and fire monitoring has become an important task for the protection of forest resources. Remote sensing technology has become one of the most commonly used tools for wildfire monitoring and fire point identification. However, single-source remote sensing data cannot meet the fire monitoring requirements of temporal resolution and spatial resolution simultaneously, which affects the efficiency and timeliness of monitoring. With the wildfire in Wakeliangzi, Xiangjiao township, Muli county, Liangshan Yi Autonomous Prefecture, Sichuan Province, China, on March 28, 2020 as the study object, fire monitoring was carried out based on a collaboration of multi-source remote sensing data acquired by the Sentinel-2 satellite, Landsat-8 satellite and the GF-4 satellite. Based on the integrated shortwave and infrared bands of the Sentinel-2 satellites, which were sensitive to fire information, the fire patch was analyzed. The normalized differential vegetation indexes (NDVIs) and normalized burn ratios (NBRs) were calculated before and after the fire, and then, the burned area and fire severity were calculated based on the obtained NDVIs and NBRs. We performed time series monitoring of the fire points based on the remote sensing data acquired by the GF-4 satellite with a high temporal resolution. Moreover, according to the remote sensing data in the medium-wave infrared band, which is sensitive to fire information, the wildfire point was located based on the smoke screen and temperature. Lastly, we calculated the vegetation coverage based on the data from the Sentinel-2 satellites and analyzed the relationship between vegetation coverage and fire severity. With the remote sensing data acquired by the Landsat-8 satellites in the integrated shortwave and infrared bands, the spatial distribution of the fire patch was quickly and effectively obtained. The total burned area reached 180.37Km2, 117.24Km2 of which had a low fire severity, 27.05Km2 featured a medium fire severity and 45.09Km2 had a high fire severity. Compared with the results of manual visual interpretation and cross validation of published results, the recognition accuracy of different fire areas is better. The multispectral data and medium-wave infrared band data acquired by the GF-4 satellite enabled us to locate the fire point and monitor the dynamic time series of the fire. The linear regression showed that the vegetation fractional cover (VFC) was significantly correlated with the relative differenced normalized burn ratio (dNBR). By combining the high temporal-spatial resolution remote sensing data acquired by the Sentinel-2 satellites and the GF-4 satellite, wildfires can be dynamically monitored and quantitatively analyzed, thereby achieving precise, macro-level fire monitoring. The findings in this study not only provide information for the Muli fire, but the results also offer a technical reference for wildfire remote sensing monitoring and emergency response.

Quantification of leaf patch distribution of endangered species <i>Euryale ferox</i> Salisb. using a 3-dimensional laser scanner.

Quantification of leaf patch distribution of endangered species <i>Euryale ferox</i> Salisb. using a 3-dimensional laser scanner.

Designing Timber Harvesting to Enhance New Zealand Falcon Populations

ABSTRACTPrevious breeding‐season studies of threatened New Zealand falcons (Falco novaeseelandiae) in plantation forests have suggested that falcons benefit when harvesting creates a mosaic of differently aged stands, especially where young and mature tree stands are adjacent. Thus, changes in the rate and pattern of harvesting may affect habitat heterogeneity by altering the size and distribution of forest patches. We sought to determine guidelines for harvesting that would most benefit falcons by increasing the carrying capacity of the forest for falcons. We used radio‐tracking to determine the home‐range sizes of non‐breeding falcons over 3 seasons and compared winter home‐range overlap in the most‐selected land cover types by falcons (mature‐young edges and open patches) with other land cover types. The distribution of open patches and edges between mature stands and recently cleared areas affected falcon home ranges, home‐range overlap, and the likelihood of nesting. Specifically, home ranges were smaller as the density of edges and percentage of open patch increased, and there was greater home‐range overlap between individuals in the most‐selected land cover types. Numbers of falcons decreased as the size of open patches increased, concomitant with a decrease in edge size, the number of edge borders, and the number of open patches. The likelihood of nesting also decreased as open patch size increased. Our results indicate that smaller open patches spread through a forest, maximizing the amount of mature‐young edges, will favor smaller home ranges and therefore potentially greater numbers of falcons. We recommend harvesting protocols that ensure that open patches (0–3‐yr‐old stands) are <4 km2 in size and retain at least small stands of mature pine to maintain a high density of edges. Similar protocols may increase the carrying capacity for other species occurring in managed systems involving fragmented landscapes or small reserves. © 2021 The Wildlife Society.

Long‐term research catchments to investigate shrub encroachment in the Sonoran and Chihuahuan deserts: Santa Rita and Jornada experimental ranges

AbstractWoody plant encroachment is a global phenomenon whereby shrubs or trees replace grasses. The hydrological consequences of this ecological shift are of broad interest in ecohydrology, yet little is known of how plant and intercanopy patch dynamics, distributions, and connectivity influence catchment‐scale responses. To address this gap, we established research catchments in the Sonoran and Chihuahuan Deserts (near Green Valley, Arizona and near Las Cruces, New Mexico, respectively) that represent shrub encroachment in contrasting arid climates. Our main goals in the coordinated observations were to: (a) independently measure the components of the catchment water balance, (b) deploy sensors to quantify the spatial patterns of ecohydrological processes, (c) use novel methods for characterizing catchment properties, and (d) assess shrub encroachment impacts on ecohydrological processes through modelling studies. Datasets on meteorological variables; energy, radiation, and CO2 fluxes; evapotranspiration; soil moisture and temperature; and runoff at various scales now extend to nearly 10 years of observations at each site, including both wet and dry periods. Here, we provide a brief overview of data collection efforts and offer suggestions for how the coordinated datasets can be exploited for ecohydrological inferences and modelling studies. Given the representative nature of the catchments, the available databases can be used to generalize findings to other catchments in desert landscapes.

Multi-Time Scale Evaluation of Forest Water Conservation Function in the Semiarid Mountains Area

Forest water conservation function is an important part of forest ecosystem services. The discontinuous distribution of forests in semiarid areas brings difficulties to the quantitative evaluation of forest water conservation functions at the basin scale. In this paper, we took the upstream of Xiong’an New Area (Zijingguan—ZJG, Zhongtangmei—ZTM and Fuping—FP basins) as an example and combine the soil and water assessment tool (SWAT) and the water balance method to calculate the amount of forest water conservation (AFWC) at annual, monthly and daily scales from 2007 to 2017, and analyzed the changes of AFWC. The results showed that the hydrological response unit (HRU) generated with the threshold area zero can accurately reflect the forest patch distribution in the three basins. On an annual scale, the annual AFWC were all positive in ZJG and ZTM basins from 2007 to 2017. While, the annual AFWC in the FP basin was negative in 2009, 2013, 2014 and 2017. On a monthly scale, the positive values of AFWC mainly appear from June to September, and the negative values of AFWC mainly appear from December to March. On a daily scale, the AFWC during extreme precipitation was positive, while that was negative during extreme drought. The annual and monthly AFWC in the three basins was positively correlated with the wetness index, and FP basin needs more humid climate conditions than ZJG and ZTM basins to make the forest store water and keep in a stable water storage state. The above results can not only provide important insight into sustainable forest and water resources management in the region, but also serve as reference cases for other regions to carry out relevant research work.

Structure-preserving dynamic texture generation algorithm

A dynamic texture refers to a sequence of images with regular and periodic changes in appearance from one image to another. Typical dynamic textures include burning flames, waving flags and flowing water. Given a reference dynamic texture, dynamic texture generation is meant to generate new dynamic textures that are of similar appearance to the reference one but are more diversified in terms of dynamics (i.e., periodic pattern changes). Existing dynamic texture generation algorithms may suffer from partially losing appearance information of the reference dynamic texture, resulting in such problems as structural distortion and blurred edges in the generated dynamic textures. To address this issue, we propose in this paper a structure-preserving dynamic texture generation algorithm based on a new two-stream convolutional networks model with feature reuse strategy (TSCN-FR). The proposed TSCN-FR makes use of spatial co-occurrence feature matrices to capture the spatial structure correlation of dynamic textures, thus alleviating the structural distortion and disordered color patch distribution in the generation of dynamic textures. In addition, an edge-preserving regular term, which uses the edge features of the reference dynamic texture extracted by the LoG operator, is introduced in the training of TSCN-FR to better maintain the edge structure of the reference dynamic texture. The application of our proposed method to dynamic style transferring is also presented. Experimental results have shown that our method for dynamic texture generation improves the existing methods by a clear margin on the ability to keep appearance information of the reference dynamic texture.

Occurrence Distribution of Polar Cap Patches: Dependences on UT, Season and Hemisphere

AbstractPolar cap patches are islands of enhanced electron density in the polar cap F region ionosphere, which sometimes affect the propagation of trans‐ionospheric radio waves. Considering the intake of daytime sunlit plasma by the high‐latitude convection as the primary cause of patches, the spatial overlap between the convection and the daytime sunlit plasma should be one of the critical factors controlling the generation of patches. To confirm this hypothesis, we statistically investigated the UT and seasonal distributions of patch occurrence frequency in both the hemispheres by using in situ plasma density data from the Swarm satellite. As a result, it was found that the occurrence distribution of patches is a complex function of UT, season and hemisphere, but it can be mostly interpreted by the spatial overlap between the high‐latitude convection and the solar terminator. This suggests that polar cap patches are not necessarily phenomena that occur only during winter months. That is, patches can often be observed even in periods away from the winter solstice if the location of solar terminator in the magnetic coordinate system is appropriate for the generation of patches. For example, in the southern hemisphere, where the offset between the geographic and magnetic poles is larger than that in the northern hemisphere, the highest patch occurrence rate is obtained around the equinoctial periods. These results indicate that it is needed to take these dependences into account when we discuss and predict the space weather impacts of patches on the trans‐ionospheric radio propagation.

Opinion evolution in the presence of constant propaganda: homogeneous and localized cases

The opinion evolution of a group of agents arranged in a square lattice in the presence of external constant propaganda is studied. The contagion between agents is modeled according to the voter model, but the effect of external propaganda and a social temperature is also considered. At a first stage, the influence of the contagion probability, the temperature, and the value of the propaganda are analyzed for a homogeneous application of this last parameter. An analytical expression was found for the stationary state in some cases. Also, the effect of the spatial location of the propaganda is analyzed, where it is applied only to a subset of agents. The random distribution of agents affected by the propaganda was found to be the most effective, while for the case of distribution in patches and stripes, it depends on their size.

Fire mosaics in south-west Australian forest landscapes

In fire-prone environments, prescribed burning is important for achieving many public land management objectives including protecting communities and the environment from damaging bushfires. There is evidence that in some biomes, reducing the size of burnt patches and creating a fine-scale mosaic of vegetation at different times since last fire (seral stages) may benefit biodiversity. However, planning and implementing an ongoing burning program to achieve this is problematic. To advance an understanding of the factors affecting burn patch size and seral diversity metrics, a novel experimental management trial that aimed to create and quantify a fine-scale fire mosaic was implemented in a south-west Australian forest landscape. The 10-year trial demonstrated that the fire mosaic characteristics, including diversity of seral stages, burnt patch size, patch distribution and patch connectedness, can be managed to a large extent by ignition frequency, which affects landscape fuel flammability, and the timing of the introduction of fire with respect to weather conditions. In this trial, the frequent introduction of fire under low to moderate Forest Fire Danger Indices resulted in a landscape comprising a quantifiably higher diversity of seral stages and smaller burnt patches than adjacent areas treated by fuel reduction prescribed burns and by a high intensity bushfire.

Multi-Scale and Multi-Direction GAN for CNN-Based Single Palm-Vein Identification

Despite recent advances of deep neural networks in hand vein identification, the existing solutions assume the availability of a large and rich set of training image samples. These solutions, therefore, still lack the capability to extract robust and discriminative hand-vein features from a single training image sample. To overcome this problem, we propose a single-sample-per-person (SSPP) palm-vein identification approach, where only a single sample per class is enrolled in the gallery set for training. Our approach, named MSMDGAN + CNN, consists of a multi-scale and multi-direction generative adversarial network (MSMDGAN) for data augmentation and a convolutional neural network (CNN) for palm-vein identification. First, a novel data augmentation approach, MSMDGAN, is developed to learn the internal distribution of patches in a single image. The proposed MSMDGAN consists of multiple fully convolutional GANs, each of which is responsible for learning the patch distribution within an image at a different scale and at a different direction. Second, given the resulting augmented data by MSMDGAN, we design a CNN for single sample palm-vein recognition. The experimental results on two public hand-vein databases demonstrate that MSMDGAN is able to generate realistic and diverse samples, which, in turn, improves the stability of the CNN. In terms of accuracy, MSMDGAN + CNN outperforms other representative approaches and achieves state-of-the-art recognition results.

Texture Memory-Augmented Deep Patch-Based Image Inpainting.

Patch-based methods and deep networks have been employed to tackle image inpainting problem, with their own strengths and weaknesses. Patch-based methods are capable of restoring a missing region with high-quality texture through searching nearest neighbor patches from the unmasked regions. However, these methods bring problematic contents when recovering large missing regions. Deep networks, on the other hand, show promising results in completing large regions. Nonetheless, the results often lack faithful and sharp details that resemble the surrounding area. By bringing together the best of both paradigms, we propose a new deep inpainting framework where texture generation is guided by a texture memory of patch samples extracted from unmasked regions. The framework has a novel design that allows texture memory retrieval to be trained end-to-end with the deep inpainting network. In addition, we introduce a patch distribution loss to encourage high-quality patch synthesis. The proposed method shows superior performance both qualitatively and quantitatively on three challenging image benchmarks, i.e., Places, CelebA-HQ, and Paris Street-View datasets (Code will be made publicly available in https://github.com/open-mmlab/mmediting).

Ebullition dominates methane fluxes from the water surface across different ecohydrological patches in a temperate freshwater marsh at the end of the growing season

Measurements of the spatial heterogeneity of methane fluxes in wetlands are critical to better understand and predict methane emissions at the ecosystem scale. However, the within-wetland spatial heterogeneity of fluxes is rarely assessed. Here, we use a spatially balanced rapid chamber-based survey of methane at different ecohydrological patches within a temperate freshwater marsh. We measured fluxes exclusively from the water surface without including vegetation. We further used the data from chamber measurements to partition diffusive and ebullitive fluxes. Three ecohydrological patches were distinguishable in the marsh, defined by the type and presence/absence of vegetation. These patches were emergent vegetation, floating-leaved, and open water. Net methane fluxes from the water surface (diffusion plus ebullition) in emergent vegetation patches were larger than in the floating-leaved vegetation and open water patches (p < 0.05). Diffusive fluxes, representing a sizable smaller fraction of net fluxes, were larger in vegetated than in unvegetated patches (p < 0.05), while ebullitive fluxes mirrored the magnitude and differences observed in the net fluxes. Moreover, pooled net and ebullitive fluxes across patches (but not diffusive fluxes) were negatively correlated with water levels, the primary variable affecting patch distribution. Altogether, our results indicate that the differences among ecohydrological patches are driven by ebullition, ultimately highlighting challenges faced by scientists and practitioners in the field and modelers seeking to improve the predictability and resolution of wetland biogeochemical models.

Multiple pathologies in an amateur soccer player with severe chronic traumatic encephalopathy

AbstractBackgroundChronic traumatic encephalopathy (CTE) is a tauopathy associated with repeated brain injuries. The presence of co‐pathologies is not uncommon in individuals with CTE. Here, we described clinical and neuropathological findings of amateur soccer with a history of progressive parkinsonism and dementia.Method63‐years old male with no family history of neurodegenerative disease or alcohol abuse. He played amateur soccer as a goalkeeper for 42 years. Episode of concussion with loss of conciseness at age of 20, without symptoms afterward. He denied any non‐soccer related episodes of brain trauma. At the age of 65, he started with REM behavior disorder, followed by apathy. At age 67, he developed asymmetric bradykinesia, limb rigidity, and complete anosmia. At the age of 73, a neurological examination demonstrated asymmetric parkinsonism, worse in the left. He denied motor fluctuations or hallucinations. At age 75, cognitive impairment was observed and his MMSE score was 22/30 with temporal disorientation, executive and delayed recall impairments. The working diagnosis was Parkinson's disease dementia. He died at age of 81.ResultNeuropathological examination showed prominent frontal and temporal atrophy, hippocampal asymmetry and moderate depigmentation of substantia nigra, and locus coeruleus. Hematoxylin and eosin staining showed left hippocampal sclerosis and white matter arteriolosclerosis. Immunohistochemistry evaluation showed aggregates of hyperphosphorylated tau in neurons, astrocytes and cell processes in a patch distribution around vessels, with deep sulcal accentuation in several cortical regions fulfilling criteria for CTE stage III. Additionally, neurofibrillary pathology was found in subcortical and cortical areas (BRAAK stage V) and Aß plaques were distributed in cortical, limbic and diencephalon areas (Thal 4), altogether meeting criteria for an intermediated ADNC. Also, phosphorylated TDP‐43 immunoreactive dot‐like and neuronal cytoplasmatic inclusions were found in entorhinal cortex, amygdala and hippocampus (LATE stage 3). Moreover, diffuse Lewy pathology was observed (Braak 5 of Parkinson´s disease).ConclusionDespite showing multiple co‐pathologies, former soccer players may develop CTE changes. This case adds to the increased number of former soccer players showing dementia due to multiple pathologies and CTE. If soccer‐related brain trauma triggers multiple neuropathological processes or if they develop independently remains an open question.

A Generative Model for Generic Light Field Reconstruction.

Recently deep generative models have achieved impressive progress in modeling the distribution of training data. In this work, we present for the first time a generative model for 4D light field patches using variational autoencoders to capture the data distribution of light field patches. We develop a generative model conditioned on the central view of the light field and incorporate this as a prior in an energy minimization framework to address diverse light field reconstruction tasks. While pure learning-based approaches do achieve excellent results on each instance of such a problem, their applicability is limited to the specific observation model they have been trained on. On the contrary, our trained light field generative model can be incorporated as a prior into any model-based optimization approach and therefore extend to diverse reconstruction tasks including light field view synthesis, spatial-angular super resolution and reconstruction from coded projections. Our proposed method demonstrates good reconstruction, with performance approaching end-to-end trained networks, while outperforming traditional model-based approaches on both synthetic and real scenes. Furthermore, we show that our approach enables reliable light field recovery despite distortions in the input.

Targeting mailed nicotine patch distribution interventions to rural regions of Canada: protocol for a randomized controlled trial

BackgroundQuitting smoking is the most effective way of reducing the risk of cancer among smokers. One way of helping people stop smoking is to provide them with free Nicotine Replacement Therapy (NRT), such as when NRT is sent to people by postal mail as part of a mass distribution initiative. Our previous research indicated that there may be a substantial impact on increasing quit rates of a mailed NRT intervention in rural areas. The current research seeks to confirm this finding and to understand the social determinants of health driving these anticipated large effects.Methods/designTelephone numbers will be randomly selected from across rural regions of Canada in order to recruit adult smokers interested in completing a smoking survey and willing to be interviewed again in 6 months. The survey will ask participants about their smoking history, demographic characteristics, and a hypothetical question: would they be interested in receiving nicotine patches if they were provided to them free of charge? Half of the smokers interested in receiving nicotine patches will be selected by chance and offered the NRT package. The other half of smokers will not be offered the nicotine patches. In addition, the municipality where each participant lives will be identified and, once the relevant general population data becomes available, attempts will be made to link participant data to relevant municipal characteristics (e.g., smoking rates, availability of health services). Characteristics of the participants and the municipalities in which they live will be used to explain why the nicotine patch intervention may have a larger impact in some rural regions compared to others.DiscussionThe findings from the proposed RCT are timely and of high relevance as the distribution of nicotine patches has substantial potential to combat the public health problem of cigarette related cancer, other diseases, and premature death from tobacco use. Targeting such tobacco cessation initiatives to rural regions may substantially increase the impact of this intervention, helping to optimize the use of limited prevention resources while aiming to save the maximum number of lives.Clinical trials registrationClinicalTrials.govNCT04606797, October, 27, 2020.

Infection spreading and recovery in a square lattice.

We investigate spreading and recovery of disease in a square lattice, and, in particular, emphasize the role of the initial distribution of infected patches in the network on the progression of an endemic and initiation of a recovery process, if any, due to migration of both the susceptible and infected hosts. The disease starts in the lattice with three possible initial distribution patterns of infected and infection-free sites, viz., infected core patches (ICP), infected peripheral patches (IPP), and randomly distributed infected patches (RDIP). Our results show that infection spreads monotonically in the lattice with increasing migration without showing any sign of recovery in the ICP case. In the IPP case, it follows a similar monotonic progression with increasing migration; however, a self-organized healing process starts for higher migration, leading the lattice to full recovery at a critical rate of migration. Encouragingly, for the initial RDIP arrangement, chances of recovery are much higher with a lower rate of critical migration. An eigenvalue-based semianalytical study is made to determine the critical migration rate for realizing a stable infection-free lattice. The initial fraction of infected patches and the force of infection play significant roles in the self-organized recovery. They follow an exponential law, for the RDIP case, that governs the recovery process. For the frustrating case of ICP arrangement, we propose a random rewiring of links in the lattice allowing long-distance migratory paths that effectively initiate a recovery process. Global prevalence of infection thereby declines and progressively improves with the rewiring probability that follows a power law with the critical migration and leads to the birth of emergent infection-free networks.

Free, easy and effective: how young adults used 8 weeks of mailed nicotine patches and to what effect

AbstractIntroductionResearch shows the mass distribution of free nicotine replacement therapy (NRT) is a high-impact, population-level strategy for smoking cessation; but underrepresentation of younger, and/or lighter, smokers challenges generalisability of findings to young adult smokers.AimsThis naturalistic study examined how and with what effect young adult smokers used free nicotine patches provided through a mass mailout programme.MethodsIn total, 5,025 eligible 18–29 year-old smokers who accessed an online ordering platform received self-help materials and an 8-week course of patches matched to their consumption level (&lt;10 cigarettes per day (cpd); ≥10 cpd). No other behavioural support occurred. Whether participants used patches correctly and achieved 30-day continuous abstinence at 6-month follow-up were assessed.ResultsAmong 694 participants with complete data: 89% used some patches; 8% used the patches correctly for 8 weeks; 31.0% (95% confidence interval (CI) = 27.6, 34.7) achieved abstinence. Adjusted logistic regression analysis showed the highest odds of abstinence was associated with the correct use of patches (odds ratio = 2.8, 95% CI = 1.5, 5.1).ConclusionsMass distribution of free patches may be an effective public health measure for supporting younger, lighter smokers to attempt cessation, reduce consumption, or achieve abstinence. Emphasising why and how to use NRT for the entire treatment course may enhance outcomes.