A wide range of multimedia services is expected to be offered for mobile users via various wireless access networks. Even the integration of Cloud Computing in such networks does not support an adequate Quality of Experience (QoE) in areas with high demands for multimedia contents. Fog computing has been conceptualized to facilitate the deployment of new services that cloud computing cannot provide, particularly those demanding QoE guarantees. These services are provided using fog nodes located at the network edge, which is capable of virtualizing their functions/applications. Service migration from the cloud to fog nodes can be actuated by request patterns and the timing issues. To the best of our knowledge, existing works on fog computing focus on architecture and fog node deployment issues. In this article, we describe the operational impacts and benefits associated with service migration from the cloud to multi-tier fog computing for video distribution with QoE support. Besides that, we perform the evaluation of such service migration of video services. Finally, we present potential research challenges and trends. A wide range of multimedia services is expected to be offered for mobile users via various wireless access networks . ForecasIn this way, the integration of cloud computing in such wireless multimedia environments provides a set of optimization services that demand high computing and energy resources, such as video quality assessment, cache, load balancing, Adaptive Bit Rate (ABR), and others . These sInstead of concentrating data and computation in a small number of large clouds, fog computing considers that portions of the cloud services must migrate to fog nodes located at the network edge, meeting the user needs regarding delay and QoE. The main characteristic of fog computing is its topology, i.e., the geographically distributed nodes that perform computation and offer storage and network services . The basFog computing has been conceptualized to facilitate the deployment of new services that cloud computing cannot provide, particularly those demanding QoE guarantees . Fog nodTo the best of our knowledge, existing works on fog computing focus on architecture and fog node deployment issues ,10,16,17In this article, we describe the operational impacts and benefits associated with service migration from the cloud computing to multi-tier fog nodes for video distribution with QoE support. In this way, we introduce a multi-tier fog computing architecture based on SDN paradigm for video distribution. Network devices have different characteristics about processing and storage, where these devices can act as fog node to provide video optimization services, such as ABR and caching schemes, closer to the user, meeting its requirements as delay and QoE. The proposed architecture provides the cooperation between fog and cloud to run video services any VoD service provider, giving satisfactory QoE.In the proposed architecture, the cloud distributes video content and also orchestrates/controls fog nodes in a centralized fashion, while multi-tier fog nodes run multimedia services to meet user requirements. It is important to mention that besides we focus on video distribution, the proposed architecture can be adapted for other services, e.g., traffic monitoring and navigation for an autonomous vehicle, wearable applications, augmented reality, and others, that requires fog computing and service migration. The main contributions of this article are: (i) a multi-tier fog computing architecture to enable video distribution with QoE Support; (ii) a fog-enabled service migration in such architecture; (iii) the evaluation of a service migration to minimize the traffic in the core network; and (iv) the identification of potential research challenges, opportunities, and requirements for such fog environments. Based on the performed experiments, the service migration improves the QoE compared to the traditional cloud architectures for multimedia distribution.The remainder of this article is organized as follows. In Human behavior is changing from traditional communication paradigm based on voice calls or text messages to real-time video services transmitted over mobile devices, such as Smartphone, Tablets, and Notebooks . In thisABR streaming delivers adapted videos according to the different network, device, QoE, and user characteristics. Several ABR schemes have been developed, such as Apple HTTP Live Streaming (HLS), and Dynamic Adaptive Streaming over HTTP (DASH), among others . In ABR In hot spots , a group of users located in the same area, sharing the same preferences or wireless network might search and watch hit videos, causing duplicated downloads . For insIt is now widely agreed that relying only on cloud computing to provide UHD video streaming is inadequate to provide QoE support . FurtherIn this section, we introduce a multi-tier fog computing architecture based on the SDN paradigm to distribute video with QoE support. The cloud infrastructure and fog nodes work collaboratively, in which the cloud migrate multimedia services to multi-tier fog nodes in case of poor QoE. In this context, video service migration requires modification either in the computing resources  or the networking infrastructure .In such architecture, the cloud distributes video content and also orchestrates/controls the system behavior in a centralized fashion. On the other hand, fog nodes might be deployed in different levels at the network edge to provide video services closer to the users. The client requests the video content for the service provider at the cloud, and then displays for the user. Such architecture requires flexibility, programmability, and management for integrated network-centric operations, where SDN paradigm addresses such capabilities ,32. HencSDN is a promising paradigm, which provides flexibility to network management by separating the network infrastructure into distinct planes, where each plane can be programmed to meet particular application requirements . SpecifiBy following the SDN paradigm, the proposed architecture consists of four planes , three APIs , and a centralized controller. The southbound API allows the forwarding plane to communicate with the control plane, where OpenFlow  is the cThe application plane is on the top of the proposed architecture to support applications to perform different tasks. However, these applications have different requirements in terms of QoE, QoS, and security levels, which might be considered. For instance, this plane can be composed of the following applications: Stream Unit, Video Optimization Service, Authentication, Authorization, and Accounting (AAA). These modules/applications run on independent virtualized services, where the virtualization technology enables to migrate services between different tiers of the proposed architecture. The proposed architecture works with any virtualization technology, such as Virtual Machine (VM) or containers. Fog nodes do not have substantial resources as in the cloud, and thus the virtualized technology must be lightweight to provide quick deployment with low overhead, as well as enabling support for live service migration . In thisThe stream unit application distributes video content for each client request, where the client downloads the video and shows the content to the user. This application must be compatible with existing video players on mobile devices, such as ffplay . The appThe forwarding plane is located at the bottom of the SDN architecture and it is composed of (re)configurable nodes connected to a centralized controller. This plane is responsible for information maintenance, network information, and others. The cloud computing (Tier 1) distributes video content and also orchestrates/controls multi-tier fog nodes. A fog node might be deployed at the network edge in different levels: (i) ISP or BBU (Tier 2); (ii) BS or AP (Tier 3); and (iii) mobile devices (Tier 4). For instance, client might become a fog node to download and share the content among its neighbors using Wi-Fi direct, Bluetooth, or another D2D wireless technology.Management plane supports the execution of administrative and operational tasks. Some examples of such tasks are the gathering of information from the forwarding plane as well as the generation of performance reports. The management plane is composed of the following modules: service migration, orchestrator, fog administrator, and QoE/QoS meter. The QoE/QoS meter enables collecting QoE and QoS measurements using well-established tools during video content displaying. For instance, CoLisEU tool  supportsThe orchestrator module is responsible for the decision-making that considers input from different sources, such as the QoS/QoE meter and operator-specific information . In this way, this module makes decisions about video adaptation, cache, service migration, and fog deployment. For instance, if the orchestrator aims to deploy a fog node, the service migration module is responsible for steering the corresponding virtualization service in a given tier. In this context, the fog administrator module manages the instantiated fog nodes and distributes multimedia content in different fog nodes.Video services migration scheme can provide video dissemination with QoE support using multi-tier fog nodes. For instance, video service migration can be triggered by user mobility, energy conservation, traffic load reduction, or service replacement. In the proposed architecture, the cloud, i.e., Tier 1, stores, processes, and distributes adapted video content for each client request. The client sends feedback to the orchestrator at the cloud, which takes decisions according to user needs. These decisions aim at minimizing degradation of end-to-end streaming quality in the face of network and user dynamics.a priori, the migration timing depends on the inference of user mobility and the video pattern demands. Therefore, as soon as the user moves away from the fog node, the video service must be migrated to a new node to maintain QoE.Virtualization technology allows the service migration from one host  to another physical host  . Based oService migration can be divided into: non-live (“cold”) migration, where the virtualization service states are lost, impacting in service availability. On the other hand, live (“hot”) migration maintains the operation and associated states, and the service is provided uninterruptedly. In this article, we are interested in live service migration. Live service migration improves the separation of tenants and the operational management procedures since it is possible to simply migrate the entire OS and the running apps as a single unit . To perfFog computing resources can be used to provide video dissemination with improved QoE support. Since such resources are distributed along multi-tiers as virtualization services on fog nodes, it is necessary an architecture that enables the provisioning of a virtualization service on a given tier. In addition, the networking infrastructure can require modifications in order to adapt to changes in network flows due to service migrations. In this context, the use of SDN features enables fast adaptations on network paths and the conformation of access control lists (ACLs). Finally, a SDN API can support applications for the network monitoring, the discovering of possible congestions, and the mitigation of network issues in a fog scenario.In this section, we describe the experimental scenario, methodology, and metrics used to evaluate the impact of ABR streaming deployed in different levels of the network edge. Next, we analyze the impact of live VM migration between different ties of an ABR services on the video quality level.The experimental scenario has the switch Pica8  to conneTo understand the properties exposed in our experimental scenario, we collected typical delay via CoLisEU . SpecifiThe streaming unit provides an ABR service to deliver adapted videos, where the adaptation policy is rate-based, and an We considered the Big Buck Bunny, Sunflower version video downloaded from the video library . PreciseBitrate and Bitrate Switch Events: the client player tends to start the video by requesting a lower bitrate from the streaming unit, and gradually keeps increasing. The bitrate could later be reduced as soon as the rate of the playback exceeds the buffering rate, due to degraded network conditions. By lowering the bitrate of the video streaming, the client player minimizes the interruptions during the video playback. On the other hand, as soon as the network conditions improve, the video bitrate can be increased. However, frequent switching in bit rates can degrade the QoE. In this way, the initial bitrate, number of bitrate switching events, average bitrate, and final bitrate affect the user experience on consuming video services.Playback Start Time: it is the time duration before a video starts to playout, which typically includes the time taken to download the HTML page (or manifest file), load the video player plug-in, and to playback the initial part of the video.RTT: time is taken for a packet to be sent plus the time is taken for an acknowledgment that such packet is received.We applied well-known objective QoE metrics, namely playback start time and a number of Bitrate Switch . These mThe client received the video downloaded from the Tier 2 with a bitrate around 9000 kbps, i.e., Quad HD video. This performance is because fog computing reduces delay by providing computing services closer to the user. For instance, Tier 2 is a fog node deployed in the ISP, and the delay between the client and the Tier 2 is 70 ms, while the delay between the client and the Tier 1 is about 200 ms. The client received a 4K video with the maximum available bitrate by downloading it from Tiers 3 and 4. Specifically, the video downloaded from Tier 3 has a small bitrate gain compared to Tier 4. This bit rate performance is because Tier 3 is composed of a specific hardware to run the ABR unit, while Tier 4 is a smartphone that runs others applications.Based on the performed experiments, it can be seen that downloading adapted videos from the cloud do not increase the initial, final or average video bitrate compared to downloading the video from fog nodes, since the network conditions, e.g., delay, between the client and cloud impact on the performance of ABR schemes. In this way, it is important to migrate video optimization services from the traditional cloud computing to fog nodes located at the network edge, improving the QoE of delivered videos . This seDownstream: the client starts downloading the video from the Tier 1. Afterwards, the controller performs the live VM migration to the Tier 2, and then to Tier 3. (ii) Upstream: the client starts downloading the video from the Tier 3. Next, the controller performs the live VM migration to the Tier 2, and then to Tier 1. Specifically, we create and configure a KVM in each tier, to avoid compatibility problems. This configuration is an important issue, since we perform live VM migration by transferring the VM state , and then the VM is suspended at the cloud. We implemented a Web service in Python considering the We evaluate the impact of VM migration on the video quality level of two scenarios: (i) The controller migrates the streaming unit from Tier 1 to Tier 2, which takes 120 s to migrate the entire OS and the running apps. During the service migration, the client stills downloading the video from Tier 1 with lower bitrate, since we consider live VM migration. After service migration, the VM is suspended at Tier 1, and the client starts to download the video from Tier 2. The bitrate increases by downloading the video from Tier 2 since the network conditions between the client and Tier 2 is better than between the client and Tier 1. However, the client stills not receiving the video configured in 4K. Hence, the controller migrates the stream unit to Tier 3, which takes 70 s. The bitrate increases by downloading the video from Tier 4, and the client receives the video configured in 4k.By analyzing the upstream results of Orchestration: The Orchestrator might consider information about QoE, QoS, topology, video Content, operator, etc., for service migration, ABR streaming, cache schemes, and other decision-making in such multi-tier fog architecture. The orchestrator must take into account specific algorithms to decide about service migration in the case of poor QoE, where machine learning could improve the orchestrator capabilities. Additionally, orchestrator could combine both ABR and cache schemes in each tier to improve the QoE, beyond that which can be achieved by either ABR and caching running individually. The orchestrator must also deal with users mobility between different locations quite often in the current wireless network scenarios, which hamper the delivery of videos with QoE support. Decision-making schemes based on QoE assessment have a significant advantage to strike an ideal balance between network provisioning and user experience. In this way, a set of different user preferences, interests, devices, video content, and network issues must be modeled and integrated into the orchestrator to optimize and selectively cache or adapt the video content, and also to migrate services. However, it is challenging to integrate QoE assessment, management, and control schemes into the decision-making schemes. Furthermore, the fog architecture could also consider information from different sources, such as social networks, to find users located in the same the area which is sharing similar content.Rewarding Methods: It is necessary to design mechanisms for offering incentives to encourage user participation as a fog node, since it consumes computational resources and, consequently, energy. For instance, monetary schemes, coupons, virtual currency, or credit-based incentive mechanisms are the most direct rewarding methods in such case, but factors such as quantization, fairness, and effectiveness must be taken into account. In this context, it lacks a model to describe the best trade-off among rewarding methods, the overall QoE, and the individual contribution of devices for the multimedia system.Security: The authorization of the terminal equipment and the mobile subscriber to become a fog node must respect security goals, such as confidentiality, integrity, availability, and accountability. For a fog node to establish a secure communication with a client, some level of pre-provisioning  on both nodes is necessary. The minimal number of configuration parameters  for each relay must be configured for each possible peer. This configuration would increase the amount of information the relays may keep for security procedures. On the other hand, cloud-assisted security mechanisms could decrease the required local resources, but they could also increase the execution time for by AAA parties. Consequently, much rests on enabling secure and authenticated multimedia exchanges between fog nodes, which should employ trusted links.Copyright: Considering fog nodes, as third-party devices, has implications on copyright issues. Since they can be viewed as parallel and unprotected communication links, as well as they can create threats for the management of digital rights. Therefore, it is also necessary to establish a chain of trust to support this mode of operation in the light of copyright enforcement. Siting between the specified security mechanisms, it is necessary to maintain dependably of the nodes that provide the multimedia content.We identify and discuss a non-exhaustive set of four research challenges coming from the proposed multi-tier fog architecture to provide multimedia dissemination with QoE support, namely orchestration, QoE management, rewarding methods, security, and copyright.Multimedia traffic on heterogeneous mobile wireless networks is expect to maintain a significant increase in the next years. A high density of users uploading/downloading multimedia content from the cloud can outstrip the bandwidth capacity and incur in the video delivery with poor QoE. Even with C-RANs (and its optimization services), it is necessary technological advances to support this delivery respecting a satisfactory QoE. In this context, fog computing features can provide significant benefits over traditional cloud environments in the context of mobile networking.In the present article, we described the operational impacts and benefits associated with service migration from the cloud to multi-tier fog nodes in the context of video distribution with QoE support. In this context, we presented a multi-tier fog architecture based on SDN paradigm, which enabled service migration to deliver videos with adequate QoE for mobile users. Besides that, the evaluation of a service migration to minimize the traffic in the core network was introduced. Finally, we introduce trends about service migration between multi-tiers fog nodes, as well as potential research challenges and opportunities.


After publication of the original article , the autThis work was financially supported by the Polish National Science Center (NCN) grants no. DEC-2012/05/D/ST7/02072 , N N518 287540  and DEC-2012/05/B/NZ2/01618 (PJ).


Whitman Richards (1932–2016) discovered some 50 years ago that about 30% of observers from the normal population exhibit stereoblindness: the disability to process binocular disparities in either far or near depth. We review the literature on stereoblindness entailing two insights. First, contemporary scholars in stereopsis undervalue the comprehension that disparity processing studies require precise assessments of observers’ stereoblindness. We argue that this frequently leads to suboptimal interpretations. Second, there is still an open conundrum: How can the established finding that disparity is processed by a continuum of detectors be reconciled with the disability of many observers to process a whole class of far or near disparities? We propose, based upon integration of literature, that an asymmetry between far and near disparity detection at birth—being present for a variety of reasons—can suppress the typical formation of binocular correlation during the critical period for the development of stereopsis early in life, thereby disabling a whole class of far or near disparities. It is some 50 years ago that Whitman Richards (1932–2016) and colleagues in the field of stereopsis started to systematically investigate individual subject differences. One of the achievements in this field that is inextricably linked to Richards concerns stereoblindness. Richards experimentally discovered that about 30% of subjects, with apparently normal vision, lack the ability to process binocular disparities specifically in either far or near depth relative to the fixation depth .Stereoblindness has caused quite some discussion even a long time after its discovery. Although nowadays stereoblindness is replicated for a wide range of stereoscopic stimuli, the experimental importance of stereoblindness is still frequently undervalued by scholars in stereopsis. Here it is key to appreciate that for proper studies on disparity processing, and the role of stereoblindness in data interpretation, one is bound to use brief presentation durations—in the order of 100 ms—to prevent fixational eye movements in depth to compensate for a lack of far or near disparity sensitivity. We pronounce this brief presentation issue at the outset of this review because later we discuss that this is where researchers can be incautious.near depth), for behind the fixation plane (far depth), and for small disparities at the fixation plane (zero depth). The three-pool hypothesis was inspired by findings in colourblindness. In analogy with colourblindness, Next to the issue of the role of fixational eye movements, there has been quite some discussion on the neurophysiological underpinning of stereoblindness. In the next sections, we will review stereoblindness studies in psychophysics and electrophysiology, respectively. Finally, we discuss how studies in binocular correlation during a critical period for the development of stereopsis early in life can be used to explain how a continuum of disparity detectors in normal stereopsis could be reconciled with the finding that many observers are blind for a whole class of binocular disparity.n = 75) three-alternative forced-choice discriminations  indicated that a considerable portion of the subjects perceived bars that were veridically either closer or behind the fixation point, as being on fixation (Richards studied stereoblindness using a briefly flashed (80 ms) bar stimulus, ranging from −4 to +4° disparity relative to fixation. A distribution of the subjects’  also found asymmetric sensitivity for far and near disparities. They convincingly demonstrated that their experimental psychophysical results could be explained by disparity processing consisting of a continuum of disparity detectors, as opposed to the three-pool disparity processing (reviewed in One reason why stereoblindness caused discussion even a long time after its discovery is the neurophysiological basis. The population distribution results from Richards’ first experiment were consistent with three-pool disparity processing. This became influential quickly but became debated in the nineties.An early electrophysiological study by Results from monkey functional magnetic resonance imaging , as wellThese neurophysiology findings complement the psychophysical work reviewed in the previous section. We already mentioned that psychophysical studies, while experimentally finding asymmetric sensitivity for far and near disparities, demonstrated that disparity processing is reflected as a continuum . Indeed,Richards’ seminal psychophysical findings on stereoblindness were well in line with a study on binocular development in kittens with artificially induced squint . Hubel aIt has been suggested that stereoblindness can also have a different origin. For example, it may be possible that the lack of binocular neurons may be genetically endowed. Congenital anomalies of visual cortical physiology are in fact known to occur in some animals of which the Siamese cat provides the best-known example .Finally, we speculate about a mechanism based on misrouting in the optic chiasm. In the optic chiasm, axons from the temporal hemiretinae traverse to the ipsilateral cortex, and axons from the nasal hemiretinae decussate, to end in the contralateral visual cortex. For a central stimulus, a near stimulus lands on both temporal hemiretinae, and a far stimulus lands on both nasal retinae . ChiasmaScholars performing stereopsis experiments know from experience that there is a considerable number of subjects who is unable to perceive depth from a whole class of disparities either in front or behind fixation. Indeed, a significant portion (estimated by Just as the use of colourblind subjects in colour-vision studies has advanced our understanding of the underlying mechanisms of colour processing, it was Richards’ hope that the wider use of stereoblindness tests would give us fundamental insights into the underlying mechanisms of disparity processing. Inspired by this line of thought, transient phenomenon that shows up only when targets are presented for a short duration (Considering that a host of perceptual properties are found to be correlated with an asymmetry in near and far disparity processing (reviewed in duration . HoweverConcerning contemporary research, After 50 years of stereoblindness, there is still an open conundrum: How can the established finding that disparity is processed by a continuum of detectors be reconciled with the disability of many observers to process a whole class of far or near disparities? We propose, based upon integration of literature, that an asymmetry between far and near disparity detection at birth—possibly being present for a variety of reasons—can suppress the typical formation of binocular correlation during the critical period for the development of stereopsis early in life, thereby disabling a whole class of far or near disparities. This proposal is in line with the above reviewed findings:


Spinal epidural abscess is a rare condition with high morbidity and mortality, for which a delay in diagnosis and treatment can lead to irreversible neurologic deficit or even death. Although patients with spinal epidural abscess have systemic predisposing immunocompromised conditions, spinal intervention, or trauma, this condition has been reported as a result of perforation or fistulization arising from inflammatory bowel disease. We describe herein a rare case of spinal epidural abscess as a complication of ileal pouch anal anastomosis.A 37-year-old man who had previously undergone restorative proctocolectomy and ileal pouch anal anastomosis for ulcerative colitis presented with complaints of persistent low-grade fever and lumbago with unusual sensation in the lower legs. After evaluation by Gastrografin contrast radiography, computed tomography, and magnetic resonance imaging, he was diagnosed with a spinal epidural abscess extending from L5 to S1. In addition, the abscess communicated with the ileal pouch. He underwent surgical drainage of the abscess, excision of the fistula, and defunctioning ileostomy. Although a second operation for drainage was required for residual presacral abscess, there was no sign of recurrence of the spinal epidural abscess. He eventually was able to close his stoma.Although spinal epidural abscess is a rare complication, one should take this condition into account when patients complain of back pain or neurologic symptoms of the lower extremities, given the possibility of fistulous communication between the ileal pouch and spine. Fistulization is a rare complication of ulcerative colitis during its natural course. However, approximately 5 % of patients after ileal pouch anal anastomosis (IPAA) experience fistula or abscess formation related to the ileal pouch –3. PouchA 37-year-old man complained of lumbago that had persisted for 4 months. He had been diagnosed with ulcerative colitis at the age of 29 years, and had undergone restorative proctocolectomy and hand-sewn IPAA when 33 years old for ulcerative colitis refractory to medical treatment and suspicion of dysplasia. Pathologic evaluation revealed no malignancy in the resected specimens. After IPAA, he had a history of chronic pouchitis, which required continuous antibiotic therapy.Although he had persistent low-grade fever and bilateral paresthesia of the outer thigh, the patient did not complain of weakened muscles apparent in the lower legs. He had no complaints of urinary retention or fecal incontinence. Laboratory tests disclosed elevated inflammatory status . Gastrografin contrast radiography of the ileal pouch revealed contrast leakage from the ileal pouch extending into the L5/S1 epidural space Fig. . MagnetiThe patient was admitted to our department for drainage of the spinal epidural abscess. In this case, where causative bacteria should be of enteric origin, we used cefmetazole for empirical antibiotic treatment to cover gram negative bacilli and anaerobes. At surgery, the fistula was observed to originate at the staple line of the top of the pouch in efferent limb and communicated with the promontory of the pelvis. After excising the root of the fistula, suspected to be a possible source of spinal infection, the foramen was closed and a diverting loop-ileostomy procedure was performed.Although abdominal distension caused by postoperative ileus persisted, his postoperative course was generally favorable, and he was discharged after 28 days. Ten months after surgery, laboratory tests showed an elevated white blood cell count  and C-reactive protein level (3.61 mg/L), leading us to suspect a residual abscess. MRI and Gastrografin radiographic examination showed a fistula arising from the ileal pouch to the presacral space, but a spinal epidural abscess could not be detected Fig. b. The pSpinal epidural abscess is an uncommon disease that accounts for 0.2–1.2 cases per 10,000 hospital admissions, with a relatively high rate of associated morbidity and mortality , 5. MostBecause epidural infection can injure the spinal cord either directly by mechanical compression or indirectly as a result of vascular occlusion caused by septic thrombophlebitis, the associated neurologic dysfunction and mortality are high . EspeciaPatients with unexplained persistent or recurrent epidural infection should be carefully inspected for rare sources of infection. In the case of thoracolumbar abscesses, an intestinal–spinal fistula may be causative .Inflammatory bowel disease, especially Crohn’s disease, is complicated by perforation, abscess, and fistula in approximately 30–50 % of cases , 9. FistIn ulcerative colitis, fistula formation is relatively rare. However, 5–10 % of cases after IPAA have been reported to develop pouch-related fistula , 18. OnlIn the present case, we precisely diagnosed a spinal epidural abscess resulting from an ileal pouch spinal fistula, and assessed the neurologic impairment as stage 2 disease. We performed diverting ileostomy, with thorough drainage and debridement of the abscess. At the initial operation, we mainly intended to eradicate the epidural abscess by fecal diversion. At the second operation, although a presacral residual abscess had been observed, the spinal epidural abscess was cured completely. In line with a previous report that ileal pouch-related pelvic sepsis might be refractory to various treatments , we alsoTo the best of our knowledge, this is the first case in the English literature of spinal epidural abscess attributable to an enteroepidural fistula arising from the ileal pouch while retaining intestinal continuity. Although pouch-related spinal epidural abscess is an extremely rare complication of ulcerative colitis after IPAA, one should include this condition in the differential diagnosis when encountering patients with systemic inflammation and neurologic impairment.


Furthermore, when current density increases to 1 C, a discharge capacity of 331 mAh·g−1 is still attainable. Due to the hierarchical porous framework and oxygen/nitrogen co-doping, the S/ONPC composite exhibits a high utilization of sulfur and good electrochemical performance via the immobilization of the polysulfides through strong chemical binding.In this work, a facile strategy to synthesize oxygen and nitrogen co-doped porous carbon (ONPC) is reported by one-step pyrolysis of waste coffee grounds. As-prepared ONPC possesses highly rich micro/mesopores as well as abundant oxygen and nitrogen co-doping, which is applied to sulfur hosts as lithium/sulfur batteries’ appropriate cathodes. In battery testing, the sulfur/oxygen and nitrogen co-doped porous carbon (S/ONPC) composite materials reveal a high initial capacity of 1150 mAh·g For example, Xi et al. prepared abundant porous carbon samples from different zinc-containing metal-organic frameworks, which possessed both mesoporosity and microporosity for good sulfur loading and electrochemical utilization . A poroucathodes .3 to host sulfur as a Li/S battery cathode. The resulting cathode yields a large reversible capacity and retains a stable reversible capacity even after the 300th cycle of the charge/discharge process at 1 C [However, the weak mutual effect between carbon host and sulfur, based on physical adsorption, limit the aforementioned designs. Recently, heteroatom dopants, such as oxygen and nitrogen, on carbon materials has been found to play an important role in trapping lithium polysulfides via strong chemical binding ,10,11. F−1 [−1 in lithium-ion batteries, respectively [−1 after 100 cycles at 0.1 C [Although the above S/C composite materials are well designed at the lab scale, they are still far from commercialization because of the relatively high cost and complicated synthetic approaches. Therefore, there is a need to focus on the preparation of low-cost carbon materials for facilely hosting sulfur. Notably, porous carbons from biomass materials have shown their potential in Li/S battery systems due to their abundance and environmental friendliness as well as the possibility of avoiding the use the sophisticated chemical procedures, in introducing heteroatom dopants into the carbon matrix ,13,14. O−1 . Jiang eectively . Zhang eSpent coffee grounds is an agricultural waste with a high yield across the globe. It is a promising carbon precursor for producing low-cost activated carbon, and its application in anodes for lithium-ion batteries has been reported in previous study . To the best of our knowledge, little attention has been paid to the feasibility of porous carbon derived from waste coffee grounds to composite with sulfur for Li/S battery cathode application. In this study, waste coffee grounds was selected as a precursor to prepare oxygen and nitrogen co-doped porous carbon (ONPC) as a conducting matrix to host sulfur for the fabrication of cathodes for Li/S batteries. The effects of pore structure and oxygen/nitrogen co-doping on the electrochemical performance of the S/ONPC composite cathodes were investigated systematically.2 in the weight ratio of 1:1 was wet ball-milled with a small quantity of DI water at 200 rpm for 3 h. The obtained paste mixture was thoroughly dried at 90 °C for 12 h. After the water had evaporated, the sample was carbonized at 900 °C for 3 h under an Ar flow. Finally, the black ONPC was produced after washing by 0.6 M HCl and DI water alternately and drying in vacuum at 60 °C. The S/ONPC composite was prepared via a solvothermal synthesis method [2 solution with 50 wt % S for 2 h. After drying, the resulting black sample was placed in a ceramic boat and calcined at 150 °C for 10 h in a N2 flow to obtain the S/ONPC composite. The ONPC was prepared by the thermal carbonization of waste coffee grounds. Firstly, waste coffee grounds were ultrasonically cleaned with deionized (DI) water several times and dried at 60 °C under vacuum for 12 h. Then the mixture of the waste coffee grounds and ZnCls method . Firstly−1.X-ray diffraction (XRD) was used to analyze the crystalline structure of the samples via D8 advance  with Cu Kα radiation. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images were obtained on a scanning electron microscope  and transmission electron microscope . Dispersive Spectrometer (EDS) mapping was performed by TEM at 160 kV to analyze the elements distribution. X-ray photoelectron spectroscopy (XPS) was utilized to analyze the chemical composition via PHI 5000C ESCA System . The nitrogen adsorption/desorption isotherms were measured via Quabrasorb, SI-3MP . Thermogravimetric analysis  was carried out from 25 to 700 °C with a heating rate of 10 °C·minN-methyl-2-pyrrolidinone (NMP) solution with a mass ratio of 8:1:1 to obtain a homogeneous slurry. The above slurry was spread on an Al foil current collector and subsequently dried in vacuum at 60 °C for 12 h. Before assembling the cells, the sulfur cathode was cut into disks with a diameter of 12 mm. The active materials loading on each disk was controlled to 2–2.5 mg. The electrolyte was 1 M lithium trifluoromethanesulfonate (LiCF3SO4) in a mixed solution of dimethoxy ethane and 1,3-dioxolane . The coin cells (CR2025) were assembled in an Ar-filled glove box  and aged for 12 h before battery tests. A battery test instrument  was used for investigating the cell cyclability at different current densities in the voltage range of 1–3 V vs. Li+/Li. The Versa STAT electrochemical workstation  was used to test electrochemical impedance spectroscopy (EIS) in the frequency range of 0.01–100 kHz. For sulfur electrodes, the S/ONPC composite was mixed with acetylene black and polyvinylidene fluoride (PVDF) binder dissolved in 2·g−1 with the pore volume of 0.48 cm3·g−1. After the impregnation of sulfur, the surface area of the S/ONPC composite was only 22.4 m2·g−1 with the pore volume of 0.015 cm3·g−1. The significant reduction in surface area and pore volume is mainly ascribed to the encapsulation of a large amount of sulfur in ONPC. In general, the ONPC possesses a large pore volume and abundant specific surface area, which could effectively retard the diffusion of polysulfides and diminish the shuttle effect in the charge/discharge process of an Li/S battery [ battery ,21.N and pyridinic-N [x (168.5 eV), as shown in The XPS spectra were used to determine the surface chemistry of the S/ONPC composite. The XPS survey spectra of S/ONPC a shows fidinic-N . It is ridinic-N ,23. As fidinic-N . Accordiidinic-N . The S2p8 to soluble long-chain lithium polysulfide  and the decomposition of the lithium polysulfide to form insoluble short-chain lithium polysulfide  [2S/Li2S2. The first discharge and charge capacities of the S/ONPC composite are 1150 and 1206 mAh·g−1, with an initial coulombic efficiency of 95%. Meanwhile, the second cycles deliver about 1073 mAh·g−1 with no obvious capacity fading, suggesting that the O/N co-doped hierarchical porous carbon frame can actually restrain the dissolution of the lithium polysulfides and minimize the shuttling loss. The S/ONPC composite exhibits a good cycling ability when tested as a cathode against lithium metal at a current destiny of 0.2 C  . The chaof 0.2 C b. After The EIS results of the ONPC and S/ONPC electrodes measured with an amplitude of 10 mV are displayed in The excellent cycling performance and rate ability of the S/ONPC composite can be related to the good conductivity of the O/N co-doped carbon frame, the adequate sulfur content, and the hierarchical porous structure. Firstly, the good conductivity of ONPC can support the fast transport of electrons into the sulfur or polysulfides and enhance the active materials utilization in the cathode. Secondly, the existence of the O/N-doped functional groups results in the good interfacial adhesion between the active materials and the electrolyte, and restrains active sulfur material loss. Moreover, the hierarchical porous structure of the S/ONPC composite provides moderate to large pore volume and specific surface area, which suppress the composite interface damages and the abuse of volume change during the cycling process.2·g−1, a high pore volume of 0.48 cm3·g−1, and a meso-/microporous structure, which is appraised as the cathode scaffolds for Li/S batteries. We have demonstrated the effect of porosity and oxygen/nitrogen doping of ONPC on the electrochemical performance of Li/S batteries. In the view of the feasible preparation approach and good electrochemical performance, the novel S/ONPC composite may become a promising cathode material in the research of Li/S batteries.In summary, oxygen and nitrogen co-doped porous carbon (ONPC) has been successfully synthesized from a direct carbonization procedure by using “zero cost” waste coffee grounds as precursors. The as-prepared carbon possesses an abundant surface area of 1017.5 m


Pulmonary arteriovenous malformation (AVM) is not routinely appreciated during the standard echocardiogram to assess for structural abnormalities or pulmonary hypertension. The distal pulmonary AVM is suspected only if an injection of agitated saline is performed and late entry of particles is appreciated in the left heart structures. A large or complex pulmonary AVM can result in significant right-to-left shunting and consequential systemic hypoxemia in the presence or absence of pulmonary hypertension. For direct visualization of the pulmonary AVM, computerized tomography (CT) scan is the procedure of choice. Here, we present two young infants with systemic hypoxemia who underwent standard medical management including mechanical ventilation and one patient was placed on extracorporeal membrane oxygenation (ECMO) before the diagnosis of pulmonary AVM was established. Subsequently, both patients have done well into mid-term follow-up after being treated successfully using transcatheter occlusion techniques in the cardiac catheterization laboratory during early infancy. We aim to emphasize the importance of a high index of suspicion for pulmonary AVM in infants with refractory systemic hypoxemia of unclear etiology. Systemic hypoxemia in infants is commonly due to pulmonary parenchymal disease, pulmonary hypertension with atrial level right-to-left shunting, structural heart disease, or a severe neurological insult. Once these diagnoses are ruled out the etiology of the hypoxemia often remains unclear. Because systemic hypoxemia is a significant culprit for resulting tissue hypoxia in infants, management strategies include mechanical ventilation, pulmonary vasodilator therapies, and life support strategies such as ECMO. Consequently, if the etiology remains unclear, pulmonary AVM should be considered. Although pulmonary AVM is uncommon, it is a treatable cause of hypoxemia in infants and was first described one hundred and twenty years ago during autopsy studies . It was 2) obtained via arterial blood gases on this support ranged between 42 and 69 mmHg. Repeat echocardiography confirmed a structurally normal heart, no patent foramen ovale (PFO), and no pulmonary hypertension. Since his low oxygen saturations were out of proportion to the lung disease on CXR, an agitated saline injection with echocardiography of the left heart structures was performed showing delayed (>3 cardiac cycles) entry of particles into the left atrium from the pulmonary veins  showed minimal right lower and middle lobe infiltrates. Echocardiography showed a structurally normal heart and no evidence of pulmonary hypertension. Hypoxemia persisted with pulse oximetry saturations in the mid-70s despite supplemental oxygen therapy using nasal cannula. He was subsequently intubated, ventilated, and started on inhaled Nitric Oxide (iNO) therapy with minimal improvement in his oxygen saturations to the high 70s. Due to persistent hypoxemia, he was transferred to our hospital critical care unit for possible ECMO therapy. Despite high ventilator settings, 100% fractional concentration of inspired oxygen (FiO2), and 80 ppm iNO, his pulse oximetry saturation remained in 70–80%. Partial pressure of oxygen  through a 6 Fr guide catheter and a telescoped 4 Fr multipurpose catheter . The AVM had two afferent arterial vessels which were occluded using Amplatzer Vascular Plug–II devices . The ECMO support was removed in the catheterization laboratory. She was extubated 2 weeks after pulmonary AVM occlusion and discharged home a week later. Follow-up at two years, she remains stable with pulse oximetry saturations of 98% and a normal echocardiogram.Pulmonary AVMs are abnormal direct connections between a pulmonary artery and a pulmonary vein without an intervening capillary bed. These malformations can exist as a single focal lesion or as multiple lesions and have an incidence of approximately 1 per 100,000 population with a male to female ratio ranging from 1 : 1.5 to 1 : 1.8 .The right-to-left shunting of blood secondary to a pulmonary AVM can result in systemic hypoxemia, paradoxical embolism, stroke, cerebral abscess, or pulmonary hemorrhage. In different series, 13 to 55% of patients with pulmonary AVM were asymptomatic –12. The Contrast echocardiography using agitated saline has nearly 100% sensitivity for screening patients , 15 for The main indication for treatment of pulmonary AVM includes prevention of stroke and cerebral abscess , improveTranscatheter embolization using coils has been reported previously in newborn –23. StaiPulmonary AVM is a relatively infrequent but an easily treatable cause of systemic hypoxemia during early infancy. Although pulmonary AVMs tend to present in older children and adults in both of our patients the pulmonary AVM caused significant hypoxemia in early infancy. In both of these patients, “normal” echocardiographic studies without appropriate agitated saline injections mislead the treating physicians to pursue a pulmonary parenchymal cause of hypoxemia. We stress a high index of suspicion for pulmonary AVM and a low threshold to perform an agitated saline echocardiography on patients with refractory hypoxemia, a structurally normal heart, and parenchymal lung findings inconsistent with the clinical scenario. With newer transcatheter device technology, pulmonary AVM can be treated in the catheterization laboratory without resorting to surgical resection even in early infancy.


Unlike optical filters that are assembled from filamentary absorbers, the magnet is shown to provide linear polarization as a bulk material for an extremely wide range of length-to-width ratios. In addition, the polarization plane of a given mode can be switched by 90° via a small variation in width. Our findings shed a new light on magnetization dynamics in that ferrimagnetic ordering combined with antisymmetric exchange interaction offers strictly linear polarization and cross-polarized modes for a broad spectrum of sample shapes at zero field. The discovery allows for novel design rules and optimization of microwave-to-magnon transduction in emerging microwave technologies.Linear dichroism — the polarization dependent absorption of electromagnetic waves— is routinely exploited in applications as diverse as structure determination of DNA or polarization filters in optical technologies. Here filamentary absorbers with a large length-to-width ratio are a prerequisite. For magnetization dynamics in the few GHz frequency regime strictly linear dichroism was not observed for more than eight decades. Here, we show that the bulk chiral magnet Cu It may be elliptically deformed by demagnetization fields3: For very thin films4 and filamentary magnetic rods with extremely large length-to-diameter ratios the ellipticity 8. On the one hand, involved waveguides and cavity designs were invented to produce microwaves with a high degree of circular polarization12. On the other hand magnetocrystalline anisotropy (e.g. easy-plane anisotropy) and antiferromagnetism2 might help to overcome the bad coupling with linearly polarized electromagnetic waves as these two qualities enhance the ellipticity in bulk materials. But at the same time, the frequency increases to several 10 GHz or even near-infrared frequencies (terahertz)15 where efficient waveguides do not exist. The integration of magnets with microwave electronics could be significantly improved by a ferrimagnetic insulator similar to YIG that possesses linearly polarized magnetization dynamics. However, such a material and the underlying blueprint have not yet been identified.Microwave components such as power limiters, oscillators and tunable bandpass filters exploit the precession of magnetic moments (spins). The magnetization dynamics allows one to process microwave signals in the few GHz frequency regime. In microwave filters bulk spheres prepared from the ferrimagnetic insulator yttrium iron garnet (YIG) provide for instance an excellent quality factor and a wide tunability of frequencies. In microwave circulators and isolators the nonreciprocal characteristics of magnetic materials are functionalized. For an efficient operation, the magnetization dynamics and the microwaves require a common polarization. However, this is usually not the case as the equation of motion for spin precession (Landau-Lifshitz equation) provides a circular polarizationmentclass2pt{minimtary Eqs . The sph2OSeO3. This magnet supports a helical spin order stabilized by antisymmetric exchange interaction, i.e., Dzyaloshinskii-Moriya interaction (DMI)19. Its phase diagram includes helical (H), conical (C) and skyrmion lattice (SkL) phases. Each phase is known to support characteristic spin excitations, introduced as modes +Q and −Q in phases H and C, as well as clockwise (CW), counterclockwise (CCW) and breathing (BR) modes in the SkL phase22. We observe the linearly polarized magnetization dynamics for the modes +Q and −Q of the spin-helix phase at zero magnetic field. Their frequencies are near 2 GHz which are about three orders of magnitude smaller compared to the ones of easy-plane antiferromagnets14. The modelling predicts that linear polarization is present also in almost circularly shaped samples. Furthermore, the polarization characteristics are modified and controlled by fields on the order of 10−2 T. This is not possible with antiferromagnets. A ferrimagnet with DMI allows for the polarization control of microwaves in frequency regimes that are key for modern telecommunication networks. Our findings are relevant for the efficient integration of magnets into future microwave circuitry. Magnetic insulators such as Cu2OSeO3 are particularly interesting as they provide negligible eddy current loss and small spin-wave damping23, which adds to their fascinating topological properties29.Here, we report the discovery of linearly polarized magnetization dynamics in the chiral ferrimagnet Cu2OSeO3 with lateral dimensions 2.3 × 0.4 × 0.3 mm3 on a CPW with a 1 mm-wide signal line  and exhibit εσ = 0.For pedagogical reasons, we first discuss the polarization of = 0 Fig. . In this= 0 Fig. –8. As a xy plane, i.e., Nx ≠ Ny, the polarization of the ±Q modes is no longer circular and εσ becomes nonzero. This is illustrated in the main panel of Fig. Nx ≤ 1 − Nz at different field values. We set εσ positive and negative for the long principal axis being along For a sample with ellipsoidal shape within the εσ in zero field (black lines). As soon as Nx ≠ Ny the frequency degeneracy of modes +Q and −Q is lifted, and the modes are found to be strictly linearly polarized  and −Q (dotted line) are calculated to follow step functions σ = ±1 when the sample shape deviates from a disk. The unexpectedly pronounced sensitivity regarding the sample shape is known neither from electronic excitations nor from ferrimagnets or easy-plane antiferromagnets.We first focus on εσ of a DMI-containing magnet has an impact on the spectral weights Γσ . For mode −Q, Γ− is large [dotted black line in Fig. Nx < 0.235].The characteristic shape dependence of Γσ Fig. . For theNy Fig. . An rf fH > 0, spins within the helix cant towards the field direction forming the conical state. Note that considering the ellipticities and spectral weights of both modes in Fig. Nx = 0.235 (disk-like shape). For ε− of mode −Q stays close to +1 [colored dotted lines in Fig. Nx < 0.235 and Supplementary Videos ε− = 0.999 at H = 0.5Hc2 for Nx = 0.07 (our sample) so that an rf field Γ− decreases significantly with increasing H towards Hc2 , the clockwise and counterclockwise modes are always elliptically polarized with a finite ε, whereas the breathing mode is linearly polarized by symmetry (Supplementary Note For χffe(f )34 recorded at 57.3 K in different phases of Cu2OSeO3. The resonance positions (inflection points) of the three curves coincide but the signal strength (peak-to-peak amplitude) varies. The largest signal strength is obtained for the field-polarized phase when the magnetization M of the ferrimagnet is maximum. Note that Cu2OSeO3 and the technologically relevant ferrimagnet YIG exhibit a similar magnetization μ0M of 0.13 T35 and 0.18 T36, respectively. At H = 0 where the overall magnetization of the helical phase amounts to zero, we do not find the susceptibility of Cu2OSeO3 to be reduced significantly compared to its field-polarized phase  results in long-wavelength helimagnetism 34 is calculated via f is the frequency, We connected a vector network analyzer to both ends of the CPW to excite and detect the spin dynamics by measuring the scattering parameter  −Q Fig.  was orieSupplementary InformationSupplementary Video 1Supplementary Video 2Supplementary Figure 3Supplementary Video 4Supplementary Video 5Supplementary Video 6Supplementary Video 7Supplementary Video 8Supplementary Video 9Supplementary Video 10Supplementary Video 11Supplementary Video 12Supplementary Video 13Supplementary Video 14Supplementary Video 15Supplementary Video 16


Binge-drinking in adolescents is a highly prevalent healthcare problem that associates physical and mental health complications with community implications. This paper describes the design, implementation and evaluation of the first web-based computer tailored intervention aimed at the prevention of binge drinking in Spanish adolescents.Alerta Alcohol program is based on the I-Change Model. First, feedback from focus and Delphi groups are used for cultural adaptation and to obtain further information on the items to be included on the program. A pilot study is then conducted to assess feasibility and to identify strengths and weaknesses. Second, a Cluster Randomized Controlled Trial is conducted to test the effectiveness of Alerta Alcohol in students aged 16 to 18 years. The study is performed in 16 high schools from Andalusia (southern Spain), which are randomized either to the experimental or the control condition (EC and CC). The EC receives the Alerta Alcohol intervention, which consists of four sessions at school . The adolescents are provided with answers related to their views of each scenario; this information is used to provide highly specific feedback regarding their knowledge, risk perception, self-esteem, attitude, social influence, and self-efficacy. In addition, two booster sessions are given at home to reinforce the previous messages. The CC just completes the baseline and the final evaluation questionnaires and then they are allowed to receive the intervention as well (as a waiting list). Evaluation takes place after four months. The primary endpoint is binge drinking within 30 days prior to the evaluation and alcohol use in the previous week. It is expected that Alerta Alcohol reduce the prevalence of binge drinking by 10%. Follow up analyses are carried out to determine the differences in effectiveness according to the compliance of the program .The The results are expected to be applicable and may incorporate improvements in the practice of the Healthcare and Education Systems. If the program proves to be effective, regional and eventual national implementation should be considered.NCT03288896. This study was retrospectively registered on 19/09/2017.Trial registration number :  The consumption of alcoholic beverages is a public healthcare problem worldwide, causing 3.3 million deaths every year , 2. The Alcohol drinking has become endemic, and part of the social and cultural life, resulting in a great social permissiveness and a low perception of its risks. It is widely available, easy accessible and lacks restrictive legislation . In SpaiRegarding Spanish adolescents, the national survey ESTUDES (2016) showed that the prevalence of binge drinking at the age of 16 was 37.1%, which doubled that of 14-year-olds (14.2%), and reached 44.2% at the age of 17 . These fFor predicting healthy behavior acquisition, several theoretic models, borrowed from health and social psychology, have been used . The preSpecifically, the I-Change Model focuses on three motivational factors: the person’s attitude (pros and cons) towards a certain behavior, the social influence experienced , and his or her self-efficacy expectations, which influences the intention of a person to develop a specific behaviour , 20–22.Regarding alcohol abuse prevention among adolescents, most of the programs are carried out at schools, for they are considered the most suitable places for learning interventions and where children and adolescents stay for significant amounts of time –25. In SCTT is a method of assessing individuals’ behaviors and opinions and selecting communication content on the basis of their answers, using data-driven decision rules that produce personalized feedback automatically from a database of content elements . CT has Similar previous studies, aiming to evaluate web-based healthcare programs in adults have been conducted , 33–35. Alerta Alcohol). This program is a dynamically web-based computer-tailored intervention, which is delivered at schools and is an adaptation of the Dutch program [Alerta Alcohol program is then performed.The goal of this paper is to describe the design, implementation and evaluation of the first web-based computer tailored intervention aimed at the prevention of binge drinking in Spanish adolescents , with an initial (pre-test) evaluation and a final (post-test) evaluation, performed four months after the intervention Fig. . To desihttp://www.imim.cat/ofertadeserveis/software-public/granmo/). According to the ESTUDES 2016 study, in Spain, the prevalence of adolescent binge drinking within the previous 30 days is 32,2% [p value < .05, a statistical power of .80, for a two-sided test, 615 subjects were required for the CC and 615 for the EC (1230 participants) to find a statistically significant proportion difference, expected to be of .32 for CC and. 22 for EC. Following the study by Jander et al., it has been anticipated a drop out rate of about 50%. The ARCSINE approximation was used [The study was conducted with students aged 16 to 18 years belonging to the public-school system. In order to calculate the sample size, the online GRANMO tool was used  were contacted and randomly assigned to either the EC or the CC. The participating students in the CC were considered to be on a waiting list, and were allowed to receive the intervention voluntarily once the study was finalized. For the selection of centers, the criteria were: 1. Public secondary education schools from Andalusia; 2. Belonging to provincial capitals; 3. Access to the Internet at school and an equipped ICT room available for the student. From the list of centers that met these criteria, a random selection was made.Participation in the study was confirmed by e-mail, telephone or, when necessary, by visit. A formal letter and an informative folder was sent to each center. If they accepted the collaboration, the inclusion criteria were checked.All students enrolled gave consent to participate and had an Internet access point in their homes. Those with language difficulties or those who had previously participated in prevention programs of binge drinking were excluded.The selected schools were not blinded, since the EC needs to schedule a total of four sessions during school hours. In the first session, the reference questionnaire (pretest) is filled out throughout January/February. For the second and third sessions, computerized interventions were carried out. There was a 1–2-week period between sessions. Then, in a fourth session at school, the follow-up questionnaire (post-test) was carried out throughout May/June. Each session takes approximately one hour.The CC only gets two sessions: baseline data in January/February 2017, and the follow-up questionnaire (posttest) four months later, in May/June 2017.Because this study is based on the Dutch program, it is reasonable that certain cultural differences may exist. Consequently, the first phase of the project consists of gathering 10 to 14 focus groups, each with 6–8 adolescents 16 to 18 years old, as well as, focus groups with fathers/mothers . The goaAlerta Alcohol. We designed tailored health messages about the needs of adolescents, which were assessed by Delphi expert groups. To make the program more attractive, we designed stories with avatars (based on the focus group interviews). The group of experts also reviewed and consulted the content of these stories.In a second phase, the feedback from these interviews is used for the development of the computer tailored intervention The third phase consists of piloting the Program with a sample of 100 students. The appropriateness and the feasibility were analyzed. Using scales like the Likert five-point scale, we assessed: the name of the program, joint evaluation of the web-based computer-tailored activities, extension, perceived interest, credibility, acceptability, understanding, ease of use and perceived impact.The design is developed using several strategies Fig. :Because Feedback from the participants in the pilot study was used for the final design of the program used in the CRCT, which was carried out subsequently .Alerta Alcohol program consists of preventive messages and information about the benefits of not consuming alcohol, reducing the positive attitudes and encouraging the negative attitudes towards alcohol drinking and binge drinking, as well as social influence and self-efficacy, as personalized feedback. Skills and action plans are encouraged to help the student to reject binge drinking. This information is presented as different tailored messages, personalized using the student’s first name and gender. Moreover, taking into account the results from the focus groups, we designed the program using terminology adapted to the age and gender of the participant. Finally, we designed four avatars or characters  that can be chosen by the participant as part of the story development.The Alerta Alcohol program consists of a short story in which the main character wakes up after an evening in which he/she consumed alcohol excessively, and does not remember what happened. There are two different stories based on the participant gender: one for boys and one for girls . The stories take place in three different scenarios . Under these scenarios, the story is presented and questions and tailored messages are offered. We used strategies to reinforce certain behaviors. For example, we developed different messages customized with the names of the participants to provide personalization and using elements like repetition of the answer, showing respect and empathy, counter persuasion, introducing social modeling and new beliefs, and reinforcing the positive behaviors and motivational feedback [The feedback , 42.The questions and tailored messages are related to alcohol drinking and binge drinking and based on the I-change model and its central concepts  Fig. . For allTo start the intervention, students are provided with access to a website. This website has a section in which they can create an account to get access to the intervention. In this account, they select their school, which determines their control or experimental status.The intervention consists of six sessions. A baseline questionnaire followed by three different scenarios (sessions 1–3), a fourth session in which adolescents may accept the challenge of not consuming alcohol in excess in an upcoming event, a session to evaluate the challenge (session 5), and session 6 which is the evaluation of the intervention or post-test evaluation. The control condition only receives the pre-test and post-test (sessions 1 and 6), whereas the experimental condition performs all the sessions.Participants begin responding a baseline questionnaire (with a series of measurement variables), including demographics, alcohol use behaviors, and mediator variables such us risk perception, motivational determinants  and intention to decrease alcohol consumption.In this session, participants are confronted with the first scenario (at home), in which the knowledge and risk of alcohol drinking and binge drinking are addressed, as well as the degree of danger and seriousness of binge-drinking, probability of a medical complication, and pros and cons of binge drinking. The feedback is focused on providing information on the general and individual consequences of alcohol drinking and binge drinking, as well as making the adolescent aware of the negative aspects of binge drinking and reinforcing the negative beliefs about it with the aim of changing to an attitude against alcohol abuse.In this session, participants continue with the second and third scenarios. In the second scenario , healthy messages include how to manage self-esteem, providing information on its importance. In addition, the scenario addresses issues related to social models, helping the adolescents to choose models considered most appropriate, encouraging them to seek support from friends and family members who do not drink alcohol in excess.The third scenario (a public place) addresses issues related to social norms regarding binge drinking, like the opinion of others. It helps adolescents to deal with the perceived approval of drinking among family and friends, and to choose true relationships that may help them to avoid alcohol drinking and binge drinking. In addition, questions and messages also address how to resist the social pressure to drink alcohol, coming from friends or family members.In all the scenarios, a last step is included, in which self-efficacy towards handling these situations is assessed. The answers are used to develop specific suggestions on how to cope with these situations, and specific action plans are offered to adolescents to handle alcohol and binge drinking under these scenarios. Adolescents are provided with a list of action plans for each scenario and are invited to indicate which specific action plans they are likely to undertake.The Challenge” is proposed: not to consume alcohol in excess in an upcoming drinking event. Adolescents receive an email inviting them to respond to a question on their alcohol drinking during the previous week. Then, they receive feedback on their drinking behavior in comparison to baseline, in order to create awareness of their own consumption [One week after the last scenario, an additional session is offered at home. At this point, “sumption . Afterwasumption , 27. BesOn the day after the drinking event, the adolescent is invited to respond to a brief questionnaire about it, and whether he achieved the goal of not consuming four/five glasses of alcohol. If the adolescent manages to achieve this goal, a congratulatory message is given to reinforce the positive behavior; if he did not manage to achieve it, he is asked about the reasons, so that he/she can receive feedback and information about external and internal reasons for that behavior and what to do about it. In this feedback, adolescents are encouraged to continue avoiding/reducing alcohol consumption by using a cue reminder  at the next social event , 43. FinFour months after the first session, all participants complete the evaluation questionnaire which includes the same measurement variables as the baseline questionnaire.The Challenge” (session 4). They receive a reminder two days before the drinking event. Then, two days after the drinking event a new message is sent to the participants who accepted the challenge in order to evaluate it (session 5). One and two weeks after session 6, students who have not completed it receive a reminder to complete the post-test.The first session is performed in the presence of a member of the research team. When participants create the account, they have to provide their e-mail. This e-mail is used to send invitations and reminders to participate. The first invitation is sent to the participants of the experimental condition who have not completed sessions 2 or 3. On week after completing session 3, participants receive an invitation to “In addition, schools receive reminders  to complete sessions 2, 3 and 6 (which are supposed to be implemented at schools).We use a Spanish version of the self-administered online questionnaire that was designed for the Dutch youth population, which has been previously validated , 44.Gender , age, parents’ educational level . Social status is measured by the social affluence scale . We also ask about whether they have a tablet or a smart-phone .The family functional status is evaluated with the Family Apgar Test, broadly used to evaluate the functioning of families with an adolescent child. It consists of five questions answered by a Likert three-point scale, assessing the adaptability or resource mobilization (Are you satisfied with the help you received from your family when you have problems?), participation or cooperation , development or growth (Are important family decisions discussed together at home?), resolution or capacity of spending time with a family member (Are you satisfied with the time that you spend together with your family?), and affection (Do you feel that your family loves you?) .We assess two drinking patterns: weekly drinking and binge-drinking in the previous 30 days.To assess weekly drinking behavior, adolescents indicate whether they have been drinking alcohol within the previous 7 days and if they did, how many glasses of alcohol they drunk. Based on this information we calculate the total amount of alcohol taken in the previous week .To assess binge drinking , we asked adolescents how many binge-drinking occasions they had in the previous 30 days.We explore the perception of danger related to binge drinking, as well as the seriousness of health problems related to binge-drinking , and the probability of acquiring these problems. We use Likert scales with five answer options .We explore four items measuring pros ; and four items measuring cons . We use Likert scales with five answer options .Social modeling is assessed by asking participants how often people in their environment  friend(s), girlfriend/boyfriend) drink alcohol and engage in binge drinking .Social norm is measured for each person in their direct environment  friend(s), girlfriend/boyfriend) by one item “My (e.g. mother) thinks that” …1 = “I am certainly not allowed to drink 4/5 glasses or more of alcohol” to 5 = “I am certainly allowed to drink 4/5 glasses or more of alcohol”.Social pressure is assessed by “Have you ever felt pressure from  friend(s), girlfriend/boyfriend) to drink 4/5 or more glasses of alcohol?” We use a five-point scale .Self-efficacy is measured by ten items. Each item assesses whether participants feel able not to drink in a certain difficult situation  or 4  glasses of alcohol if others around you drink 4/5 glasses or more of alcohol?”). We use a five-point scale .We used two questions about the intention of alcohol use and binge drinking with a five-point scale , “Are you intending to generally reduce your drinking in one occasion ” and “Are you intending to drink less than 4/5 glasses of alcohol in one occasion ”To assess the implementation compliance, the number or sessions performed by the participants are registered. After completing each session and in the posttest, we ask respondents whether the intervention was useful, realistic, interesting, and personally relevant on a five-point Likert scale .In the final evaluation, we also assessed the general satisfaction  and, by using a five-point Likert scale, the opportunity of learning, and the probability of using the counseling  .Alerta Alcohol platform. Then, sessions 2 and 3 are conducted by the teacher at school, and sessions 4 and 5 are self-administered by adolescents at home. The final evaluation or session 6 is again conducted by the teacher at school. Before initiating the participation in the study, parental and individual informed consent must be obtained.The implementation of the intervention is carried out in a school context and the students are who fill out the questionnaires. The first session in the different centers is guided by a member of the project, who also provides access to the website and register on the The interventions are carried out according to bioethical guidelines: the students need to answer the questionnaires themselves and confidentiality is guaranteed. Informed consent and an online form to collect data are used. The study has the approval of the Bioethical Committee of Andalusia. The registration number for clinical trial is: PI-0031–2014. Registration date: 04 August 2015.Descriptive analyses are performed to describe the characteristics of the participants. Subsequently, multivariate analyses by multiple linear regression are conducted to analyze the effect of the program on the weekly consumption of alcohol, and the intention of reducing alcohol drinking. A binary logistic regression aiming to assess the effect on binge drinking within the last 30 days is performed. The independent variable was participating vs. not participating in the program, and co-variables were the outcome at baseline, socio-demographic variables and explored risk factors, which showed significance after a previous bivariate analysis. Analyses are conducted to explore the differential effects of the socio-demographic characteristics like age, gender or social status. Cases of linearity, homoscedasticity, normality of the quantitative variables, independence of errors, and non-co-linearity are taken into account. Also, analyses are carried out to determine the differential effect, according to the program compliance , on the program outcomes. This may eventually provide information about the influence of the quality of the implementation on the program outcomes and of a possible implementation threshold effect.p < .05 is used, and the size of the effect is calculated (r coefficient and Odds Ratio), with 95% confidence intervals.The analysis of the data is supported by the R statistical program. A level of significance of Alcohol drinking in adolescents is a socio-health problem of crucial importance, because of its high prevalence and the physical and mental health risks affecting the adolescent consumers, in addition to the psychosocial and community implications derived from alcohol abuse –6, 47. TAn important issue regarding program implementation at schools is compliance according to the original scheme, since implementing school programs often requires cooperation from teachers, who may find it difficult to provide the intervention as it was originally conceived. Thus, delivering an online intervention, i.e. a web-based computer-tailored intervention, may improve the program implementation, specifically regarding its compliance, integrity, and replicability, so that objectives can be achieved .The high drop out rate is an important problem in a web-based computer-tailored intervention , 33, 49.In order to minimize the drop out rate, we followed different strategies to improve the characteristics of the program. First, we designed the intervention considering the feedbacks from focus groups with adolescents and parents. Second, we developed a dynamic intervention, with different interactions and stories adapted to gender and age . Third, Alerta Alcohol program. There are different cultural issues related to alcohol drinking among different countries. For instance, drinking behavior can be associated with certain cultural or seasonal events, such us “Spring Break” in the United States or certain folk festivals like the Oktoberfest in Germany. In Spain, there is an alcohol drinking phenomenon called “Botellón”, which is the most prevalent event for alcohol drinking in adolescent population and consists in drinking alcohol in public places [Botellón” in the last 12 months [In the adaptation of the intervention, we think that some changes were needed for the c places . In Spai2 months . This maFurthermore, since previous studies have found that a large proportion of adolescents may be in a pre-motivational phase, we believe it is reasonable to focus on prior aspects, relatively easier to modify, like factors of awareness  . In thisIn addition, we believe that it is necessary to provide with messages aiming to improve self-esteem, since low self-esteem is considered a determinant for risky behaviors in adolescents, such as alcohol drinking or binge-drinking. This is particularly relevant in the adolescence period, because self-esteem is a critical factor affecting the psychological and social fitting , 53.In summary, this study tests the effectiveness of an intervention focused on reducing alcohol drinking and specifically binge drinking in Spanish adolescents between 16 and 18 years of age. If the program proves to be effective, the ultimate goal would be regional and eventual national implementation.