This article will provide a framework for producing immersive 360-degree videos for pediatric and adult patients in hospitals. This information may be useful to hospitals across the globe who may wish to produce similar videos for their patients. Advancements in immersive 360-degree technologies have allowed us to produce our own “virtual experience” where our children can prepare for anesthesia by “experiencing” all the sights and sounds of receiving and recovering from an anesthetic. We have shown that health care professionals, children, and their parents find this form of preparation valid, acceptable and fun. Perhaps more importantly, children and parents have self-reported that undertaking our virtual experience has led to a reduction in their anxiety when they go to the operating room. We provide definitions, and technical aspects to assist other health care professionals in the development of low-cost 360-degree videos. This article aims to provide both methods and practical advice for the production of immersive 360-degree videos for children in hospitals. It is targeted at those with previous experience in the production of standard videos. Preoperative preparation of children is a well-researched method of reducing perioperative anxiety and the consequences of this anxiety . The advThere are many standard videos available online aimed at the preparation of children for their hospital procedures. It would also be possible to produce these videos in panoramic or 180-degree modes, which would be technically much easier to produce. However, children and their parents prefer using a 360-degree video. The benefits of 360-degree video over these other methods are threefold ,3:It provides a full visual account of what the child could see, there is less chance of surprise at the time of their anesthetic.The increased autonomy for the child during the process of preparation may itself lead to reduced levels of anxiety on the lead up to their anesthetic.The use of virtual reality (VR) headsets or 360 video viewers, by the very nature of being a toy, may reduce anxiety by the child associating the anesthetic with something fun.Furthermore, it has been demonstrated that health care professionals, children, and their parents find this form of preparation valid, acceptable, and fun ,3. PerhaThe production of 360-degree videos is significantly more challenging than the production of standard videos. There are many production steps which should be planned: (1) production of a script and recruitment of actors, (2) filming individual 360-degree scenes with an appropriate camera, (3) footage from each camera needs to be added together to produce the completed 360-degree video during a process called stitching, (4) the 360-degree footage needs to be edited into the completed film with appropriate software, and (5) the video file needs to be loaded onto a device supporting 360-degree video with a 360-degree viewer.As with planning the production of any video, it is essential to carefully consider what information the child will gain from the experience. It is important to optimize the length and pace of the video to ensure that it contains all the necessary information and does not result in symptoms such as motion sickness, dizziness, and headaches. An unnecessarily long video may increase the incidence of such symptoms or boredom, and the pace of the video should mimic real anesthetic experience as much as possible.A key element in this is to perform a needs assessment to gain perspective from all stakeholders. This includes surveys, interviews, and a review of pre-existing standard videos created. Decision points for 360-degree videos will include deciding which elements of standard videos will work in that format.The virtual experience appears more realistic if it flows naturally through the individual scenes rather than shorter sequences being pasted together. For this reason, it is much easier to use professional actors or staff that are acting in their usual professional roles. Even the most experienced staff member may need several takes to get the scene completed perfectly when the camera is rolling.The preoperative area: Introduction and orientation from the nurse.Walking down the corridor: The nurse explains where they are going and what they will see.Walking into the OR: Meeting everyone in the OR and being asked to get onto the bed.Lying on the operating bed: The nurse explains what she is doing while attaching all the routine monitors.The anesthetist explains what they are doing while delivering a gas induction or inserting an intravenous (IV) tube and delivering an IV induction. The screen fades to black depicting falling asleep.A brief period of darkness indicating being asleep.In postoperative care unit: The nurse explains that procedure has finished, points out remaining pieces of monitoring, IV access, and reassures the child that the parents will be arriving soon.There exists an increasing number of 360-degree cameras available to the consumer. They all have different technical specifications, associated software, and workflows for stitching images. These vary in cost as well as using rigged or non-rigged cameras. A framework and rationale for the cameras selected is provided.Two different set ups of cameras for shooting 360-degree videos were tested: (1) GoPro rig and (2) Ricoh Theta S. The first comprises a frame with 6 cameras fixed to it pointing along all 6 axes. The second was a self-contained system with two 180-degree lens cameras located back to back. Although the GoPro rigged system was superior concerning video quality, 3 significant disadvantages of this system over the self-contained 2 camera system were found. First, it was significantly bulkier and heavier which impeded setting up the camera in a number of the scenes. Second, there is footage from 6 cameras that need stitching together as opposed to 2 , greatly increasing the postproduction work-load due to the increased amount of space between cameras and the amount of footage not captured, this set-up became inferior when filming objects at close range, such as face masks .Resolution of video footage can be considered as the amount of information the camera collects in each frame. It is essential to understand that to produce a clear picture in immersive videos, a higher definition is required. This is for two main reasons. First, each frame of the video is not being watched in its entirety on a flat screen in front of the user. The information in each frame is, in fact, being stretched around a central point into a full 360-degree environment leading to a significant loss of resolution . Second,The first video was filmed using the Ricoh Theta S which claims a high-resolution of 1920 by 1080. Although the auto-stitch feature, which works well, the end product when viewed in the 360-degree viewer was of standard definition. 3/100the video complained of a blurry picture, sore eyes, and a headache. This was attributed to the low resolution of the video [For the second video, the Samsung Gear 360 was used which has a higher video resolution of 3840 by 1920. Although this device does not come with an auto-stitch feature, it can produce a much clearer higher definition immersive experience. Although not formally assessed, the higher resolution appears to cause less incidence of sore eyes and headaches.When producing non 360-degree films, the footage can be viewed as it is filmed. With 360-degree filming, everything in the line of sight of the camera is recorded, and it is not until after the stitching and into the editing process that the scene can be viewed entirely. It is a worthwhile exercise to have dry runs of each scene with someone in the position of the camera looking around the entire room to see exactly what the camera will see during the filming. This is especially important when filming in a hospital environment as it is easy to inadvertently film sensitive material such as a patient in the background or a piece of patient identifiable data on a computer screen.The optimal way to film the experience was to use the camera as the head of the “patient” and administer an anesthetic to the camera. This ensured that the scene felt real and also enabled the user to feel like they are being spoken to and interacted with personally during their virtual experience.To film the torso of the child and depict the application of various physiological monitors and lines, it is possible to either use a mannequin or an actor. The method we describe here uses a mannequin, but the same principles may be applied to a live model.The camera needs to be positioned on the mannequin so that the child sees the “body” as they would their own. After testing different set-up options, the optimal position to set up the camera is as depicted in One aspect of preanesthetic preparation for children which the virtual experience lends itself particularly well to is the gas induction. Holding the top of the mask 3-4 inches away from the camera and 1 inch above the center of the camera allows the child to experience how the mask will appear during a gas induction, as shown in One inherent technical problem was discovered when filming in this manner. Using the camera as the head of a body means that when the user looks down during the video, they will either see a face or a “headless” body depending on whether or not the face is covered. After multiple tests, it was discovered the most aesthetically pleasing method was to do 2 things. First, during the filming process, cover the face of the mannequin in a sheet the same color as the bed, as shown in The scene depicting the walk to the OR posed another technical difficulty. In the first attempt, the nurse escorting the patient to the OR pushed an IV stand with the camera attached to the top. This initially appeared to work well; however, it did reveal one of the side effects caused by this technology. During the virtual experience, the user remains in a sitting position and is placed in a “virtual environment” where they perceive motion, which can lead to motion sickness. The first video caused 20/57 (35%) of users to feel dizzy and 10/57 (17.5%) to feel nauseous. Subjects attributed their side effects predominantly to this scene. The scene was refilmed using an IV stand with added weights at the bottom, to increase the stability of the pole, and wheeled it down the corridor much more slowly at a speed of about 0.25meters/second. This enabled the scene to be produced where the user still gets the impression of walking down the corridor but has a much lower incidence of motion sickness. The downside to this is that it was only possible to film a small portion of the walk to the OR as it would have taken too long to walk at this speed.There are multiple ways of recording the audio for the video. The simplest option is to use the built-in microphone in the camera. This, however, does not provide the best audio quality, especially in an environment with lots of ambient noise. Voices from different locations within the environment will also be recorded at different volumes.The most reliable way to record the actors’ voices is to fit each with microphones and add this to the video at the editing stage. Regarding background sounds, which are important for the experience, such as monitoring sounds or trays being opened, it is best to film the experience in a quiet room. Separately record these sounds and then add in during the editing. It is also possible to record actors’ voices at this stage.This is a very time consuming and technically challenging task. Each frame from each camera needs to be stitched together to produce a video file that contains a full 360-degrees worth of information. The Ricoh Theta S camera allowed for a bypass to this stage as it had an auto stitch function enabling the export of data directly from the camera to the editing software. The Samsung Gear 360 did not come with this function, and it was necessary to obtain help from an outside company to complete the stitching process. This is a very significant consideration when deciding on which camera to use, as it may cost significantly more to hire outside help to complete the stitching of the footage.The editing techniques behind producing a completed video are beyond the scope of this article, and there are many editing software packages available. However, some of the fundamental concepts when editing a 360-degree video are explained here. The editing software used was Adobe Premiere.After the stitching process has been completed, the video files are in equirectangular format. This means that the 360-degree spherical images have been flattened and distorted onto a 2-dimensional rectangle, much like a map of the world. Therefore, when viewing the clips during the editing process, they will appear distorted, and it is difficult to appreciate what the final product will look like .For the final product to work as required in the 360-degree video viewer, it is vital to maintain the correct relative dimensions of the video during the import process into the editing software and during the export process out of the editing software. The exact magnitude of the dimensions will vary depending on the resolution of the clips but will need to be twice as wide as they are high . It is also vital to ensure that there are no borders to the image as the edges of the video will be wrapped around and brought together when playing on the 360-degree video viewer.Even though additional lighting was used during the filming, the finished product was still quite dark. Increasing the exposure setting by approximately 40% and the saturations setting by approximately 80% on the editing software produced a video that is much brighter and warmer. It also gives a much clearer picture. The exact degree to which these settings should be adjusted will depend on the original footage.Metadata is the information that is embedded into the video file that allows the video to be viewed in 360-degree mode. Whether or not the raw footage contains this data depends on the camera used. It may be necessary to install this metadata during the export process. Using this method, it is not necessary to do this. However, it is critical to ensure that when the video is exported from the editor that the metadata remains within the video file by enabling the metadata settings.There are a large number of devices and viewers , that allow viewing 360-degree video media. The most reliable and cost-effective way of viewing the completed video is as follows. First, download the completed video to a mobile phone. All current mobile phones have the ability to run the necessary VR applications. Second, open the video in an appropriate VR application. The free and open source VR application called Childlife VR was used. Third, view the video through a 360 viewer. These are readily available devices for mobile phones. The Google Cardboard viewer was used in this study due to its availability and price.For safety reasons, it must be ensured that all users of the video remain seated at all times during the experience. This still enables them to look all around and experience the full benefit of the video. Although most of the information happens in the “looking forward” position, children still choose to take advantage of the technology and look all around them throughout the video.This tutorial provides an account of the technical challenges encountered and techniques that were found to be effective when producing a video . There are many different ways of preparing children for a hospital procedure and not all will wish to participate in this particular way. There was 1/ 101 (1%) of the children approached to use the video chose not to try it as they had received over 8 previous anesthetics. They had their own coping mechanism and did not want this process interfered with. In addition, 6/100 (6%) children recruited preferred to use the standard methods of preparation in the future .Three-dimensional cameras and augmented reality goggles are becoming more readily available and more reasonably priced. This may represent future alternative methods used in the preparation of children for general anesthesia and other hospital procedures.


With the growth of the internet of things (IoT), many challenges like information security and privacy, interoperability/standard, and regulatory and legal issues are arising. This work focused on the information security issue, which is one of the primary challenges faced by connected systems that needs to be resolved without impairing system behaviour. Information, which is made available on the Internet by the things, varies from insensitive information  to extremely sensitive information  and needs to be secured over the Internet. Things which utilise cameras as a source of information pertain to a subclass of the IoT called IoVT (internet of video things). This paper presents secured and unsecured video latency measurement results over the Internet for a marine ROV (remotely operated vehicle). A LabVIEW field programmable gate arrays (FPGAs)-based bump-in-the-wire (BITW) secure core is used to provide an AES (advanced encryption standard)-enabled security feature on the video stream of an IoVT node (ROV equipped with a live-feed camera). The designed LabVIEW-based software architecture provides an option to enable/disable the AES encryption for the video transmission. The latency effects of embedding encryption on the stream with real-time constraints are measured and presented. It is found that the encryption mechanism used does not greatly influence the video feedback performance of the observed IoVT node, which is critical for real-time secure video communication for ROV remote control and piloting. The video latency measurement results are taken using 128, 256 and 512 bytes block lengths of AES for both H.264 and MJPEG encoding schemes transmitted over both TCP and UDP transmission protocols. The latency measurement is performed in two scenarios . The number of things that are connected to the Internet is growing considerably. Because of this, a new concept, called IoT (internet of things) is emerging . The IoTThings equipped with a camera sensor stand out from other things due to the potentially sensitive nature of information and high bandwidth requirements for the video stream transfer. Thus, a subclass of IoT called IoVT was introduced, which addresses interconnection of things with cameras as sensors . While tLack of implemented security on interconnected devices makes the IoT a darker world of surveillance; because in the IoT environment everything is potentially accessible through the Internet. So, ensuring information security on the Internet is very important to build trust in the use of Internet enabled devices. If people believe that their connected devices and their information on the Internet are not secure from misuse or harm, then they will be reluctant to use these devices. On the other hand, it is crucial that enabling information security does not significantly alter performance of the overall IoT systems.As security in the IoT is an important aspect, ranging from the technological issues to the more philosophical ones, such as trust and privacy, the security threats in the IoT can be divided into two categories : physicaIn recent years, devices with integrated micro controllers, referred to as “things” in the IoT lexicon, are being transformed from simple and low-power devices to complex devices which often utilise power-hungry sensors  and possess complex hardware architectures . The main advantage of FPGA platforms as compared to ASIC (application specific integrated circuit) platforms is flexibility, which makes an FPGA a popular platform in IoT . This maThe FPGAs (field programmable gate arrays) platform is very suitable for the implementation of cryptographic algorithms, because of its re-configurability and high performance features . InitialAlthough this research is conducted by utilizing marine robot application, the methods and results presented here can be beneficial for any remote control systems with video feedback. The encryption method is designed as a portable solution, which can be easily applied to various remote control systems. The analysis of latency (both video and network) is of great importance for systems with real-time constraints. The impact of latency on control systems is highlighted in ,13. HereAn improved version of our previously published work  in termsTo the best of author(s) knowledge, this is the first work which provides secure and unsecure video latency measurement detail analysis and comparison.The implemented encryption does not have noticeable effect on video quality.This is the first work which presents the video latency measurement results using two scenarios based on same hardware and different hardware on each end of the video communication. This shows the adoptability of the proposed work for different platforms.Main contributions of this work are as follow:The remainder of the paper is organized as follow: The importance of data security in IoT applications is highlighted in the introduction section. Data security is important for practically every Internet-connected device. The complexity of data security implementation tasks varies greatly and depends on the application and on the industry requirement for which the device is used. For example, implementation of data security for distributed control systems with real-time constraints is considered a highly challenging task. In such systems, real-time constraints apply on the process of data security provision/implementation. Distributed systems, which are connected through various networks and/or over the Internet are susceptible to latencies in data transfer, hence data processing, such as security implementation, must be conducted within the shortest possible time in order not to impair the functionality of the system. Latency analysis is an important factor in real-time communication. The developed system measures/analyses the secure video communication latency using a number of configurations based on different hardware, encoding schemes, block sizes of encryption algorithm and transport protocols.A marine system, which pertains to IoVT and IoRT, used for IRM  of wind farms and other remote offshore structures, is used as the target application in this work. This system is developed by the CRIS (Centre for Robotics and Intelligent Systems) at the University of Limerick . This deThe work of this paper mainly involves secure and unsecure video latency measurement over the Internet. As mentioned above, the target application is marine, which involves the remote control of an ROV from a control station. The encryption level security is implemented using a previously published AES  algorithAs mentioned previously, in this work an FPGA is used to provide AES security and the comparison of traditional FPGA and LabVIEW FPGA is given in .This section includes a literature review of the following: video latency measurement, packet switch network, time sensitive networking and secure video.Video latency measurement: This work is based on our previously published work  which foThe first tool is called AvCloak  and is iIt is worth noting that none of the cited papers investigated video latency measurement with and without encryption. In addition, there is no detailed analysis of the network latency component within the glass-to-glass video latency, which becomes particularly interesting if the video is transferred over a packet-switched network, which is the case for this paper.Packet switch network: A characteristic of packet-switched networks is that they do not guarantee delivery of packets within a bounded time. The end-to-end delay of a network packet consists of the following delays: processing, egress and ingress delay , packetsThe evaluation metrics for the QoS  in real-time is mandatory for certain applications like controlling a robot based on the video feedback over the Internet/LAN, which is the target application of this paper. The capabilities of data transfer speeds on Ethernet, excellent electromagnetic compatibility  and low Time sensitive networking: In recent years huge effort has been put into development of deterministic communication capabilities between devices connected over standard Ethernet. The most valuable progress, which resulted in a set of networking standards, was made by the TSN (time sensitive networking) task group which is a part of the IEEE 802.1 working group. The TSN was formed from the AVB (audio video bridging) task group which was dealing with real-time transport of audio and video over Ethernet . The resSecure video: Adding encryption to the video signal in order to provide the data security makes real-time video transfer more complex. Encryption of the video stream data has been an active field of research for a long time. The IoVT technology increased the number of video streaming devices on the Internet, which in turn increases the necessity for having high quality security solutions. Existing video encryption solutions differ based on the amount of video stream data that actually gets encrypted. On this basis, there are partial and full video encryptions. With partial techniques, encryption is conducted on part of the data necessary for scrambling the video and making it worthless without decrypting. A full video encryption technique implies encryption of the complete content of the video stream, making it more secure, but at the same time the process of full encryption requires more processing power. Full encryption can be realized by using two techniques called homomorphic and invariant encryption . These tIn Ref. , authorsThe encryption technique presented in Ref.  was applThis work provides a detailed technique for secure video transmission with thorough analysis of latency. Video and network latencies were simultaneously measured by using the software application designed/presented in this paper. While the tools presented in ,20,21 prPublications which are most relevant to this work are listed in The video latency measurement solution, which was developed and presented in , was upgThe proposed solution is highly portable and can be used for latency measurements of unsecure/secure video streams in any system which possesses transfer of video over IP. In addition, the proposed solution is modular and can be easily adapted to implement higher levels of security, instead of only encryption security.The proposed architecture is based on the video server component described in , which wTimestamp SenderCamera ServerEncrypt/Decrypt ApplicationsCamera ClientLatency Measurement.As shown in Timestamp sender and latency measurement applications screenshots of This architecture can be used in different configurations using options of protocol type, encryption string length and encoding algorithm. In terms of protocol type, there are two possible choices: UDP and TCP. This option modifies the way video data is streamed from the IP camera to the latency measurement node. When UDP is selected, all channels (both TCP and UDP) shown in Details of each node are given below:Timestamp Sender is used for generating a visual event, which is captured by the camera’s sensor. Each event is accompanied with the data containing the timestamp of the event and event ID. The event ID is a number which is incremented for each generated event. This number is displayed in the application window which is captured by the IP camera. The purpose of the event ID is to indicate the quality of the video for the end user. The timestamp is captured from windows system time with 1 ms resolution. The application acts as a server in a way that keeps a pre-defined UDP port open for client registration. Any client that sends a request packet to the port will be registered and will keep receiving the visual event data periodically. The described functionality is shown in This application node runs on the real-time target and is responsible for communication with the camera, preparing the data for encryption, adding timestamp information to packets and sending encrypted data back to the client. The server accepts connections on a pre-defined TCP port which is used for the RTSP transport initialization procedure . RTSP paOnce the connection parameters are negotiated, the video data stream is started by sending the PLAY command from the application. It is worth noting that video data are encoded by either H264 or MJPEG encoding algorithms and this process is done by the IP camera before the transmission of the data to server application. Depending on the desired transport protocol for video data transfer (TCP or UDP), the stream can be transferred over the same TCP connection on which RTSP was initiated or it can be transferred over a UDP port, which needs to be negotiated in the RTSP initialization procedure.The application node is organized in two threads as can be seen in These application nodes run on FPGA targets and are responsible for encryption and decryption of data. The BITW (bump-in-the-wire) security solution, which is explained in , has beeData transfer between applications running on the real-time processor (camera client and camera server) and applications running on the FPGA (encrypt/decrypt) is based on writing data to controls and reading data from indicators created in the FPGA application. For this purpose, a block called read/write control is used by the software on the real-time processor. For each control and indicator, a fixed size register is created on the FPGA to be accessed by the real-time processor. The main advantage of this type of data transfer, when compared to other methods ,50, is lIn order to decrypt data, it is necessary that both encrypt and decrypt VIs have the same 128-bit key set. This application node, which is also running on the real-time target, initiates connection and receives video data from the camera server application. The functionality related to parsing the RTSP packets is the same as in the server application. The client application listens on a pre-defined TCP port for incoming connections, which will be propagated to the IP camera over the camera server application. Similarly, the video stream data, which is decrypted in the client application, is sent back to the latency measurement application. Like the camera server application, the camera client application is also organized in two threads, as shown in The first step after receiving a fixed size data packet from the server is to the extract timestamp information from the packet (Step 1). After that, the packet is forwarded to the FPGA application node, which performs data decryption (Step 2). When the FPGA finishes decryption and decrypted data is read by the client application (Step 3), the network latency is calculated by subtracting the timestamp, captured from the real-time operating system time after decryption is completed (Step 4) from the timestamp, which arrived together with the data packet (extracted in Step 1). The calculated network latency is logged to file on the real-time target (Step 4). In Step 5, the decrypted video data is forwarded to the main application. It is worth noting that the data after decryption is again encoded with H264 or MJPEG algorithms (depending on the video source encoding type).This application node is responsible for various important functionalities, which include connection to the camera client, the starting sequence of RTSP packets, accepting and decoding video data, detecting events in the video and calculating the video latency. The latency measurement node also registers to the timestamp sender application node in order to be able to receive event ID and timestamp data, based on which the video latency is calculated. A pre-built FFmpeg library was used for handling the RTSP and decoding of the video. The image processing and event detection is done by utilizing the NI vision development module.As illustrated in The proposed architecture presented in IP camera model Hikvision 2CD2010F-I was used in all tests, with the following encoding parameters: resolution (640 × 480), bitrate type (variable), video quality (lowest), frame rate (25) and max bitrate (2048). As mentioned earlier, two options for encoding algorithms are possible: H264 and MJPEG. Video encoding is done on the transmitting end Dell inspiron 15 5000 series laptop PC with an intel core i7-8550U @ 1.80 GHZ processor and Intel UHD Graphics 6.20, while video decoding is done on the receiving end of the test setup by using a Dell Inspiron 7720 laptop PC with an Intel core i7-3630QM @ 2.4 GHz Processor and an NVIDIA GeForce GT 650 M graphics card.During all the tests, IP camera was located at the University of Limerick, Ireland with Internet connection bandwidth of 100 Mbps for both upload and download. In cases when myRIO was used for decryption, it was located in Sarajevo (Bosnia and Herzegovina) with Internet connection bandwidth of 4 Mbps for download and 2 Mbps for upload. In another case, when both cRIO devices are located in Limerick, Ireland, receiving end of test setup was connected to the Internet with bandwidth 96.2 Mbps for download and 86.0 Mbps for upload.The configuration shown in (1)The timestamp sender application (PC1) generates periodic visual events.(2)The camera server (cRIO 1) opens an RTSP  connecti(3)The camera client (cRIO 2) opens an RTSP connection to the camera server.(4)The latency measurement application (PC2) opens a connection to the camera client.(5)The camera server generates a timestamp before data encryption.(6)The video data is encrypted on the FPGA and the data is streamed to the listening application.(7)The camera client receives and unpacks each TCP/UDP frame.(8)The FPGA decrypts the video data.(9)The camera client calculates the network delay for each packet.(10)The latency measurement application (PC2) receives visual event information from timestamp sender.(11)When an event is detected, video latency is calculated and stored.The flow of data in the experimental configuration with encryption is as follows:It is also worth noting that encryption/decryption functionality can be easily enabled or disabled by changing the state of a switch in the software. In addition, if there is a need to test the performance of different encryption algorithms, the test can be modified in a way that only the code on FPGA is replaced, while the rest of the system remains the same.Here, the test configurations are designed as “offline” tests of video and network latency. It means the system being tested, cannot do its normal functions until the test is completed. The reason for this is that there has to be a dedicated PC with display to run the timestamp sender application. However, if there is a need to have information about video latency “online,” while the system is in normal operation, it can be done by slightly modifying the hardware and software used. Such software modification includes a change in visual event generator, which would have to be designed in a way that it is permanently installed into the camera’s field of view. In hardware modification, an embedded system with precision timing and LEDs would have to be considered instead of a PC with a display and timestamp sender application. The described modifications are not implemented as part of this publication, but are suggestions for future work.This section provides details of performance results. Each combination of options, which is supported by the equipment, was tested. These include the following options: encoding algorithm, transport protocol, encryption on or off and encrypted string length. The motivation for such comprehensive testing lies in the desire to achieve the following goals: draw conclusion about the effect of encryption on video and network latencies; determine a set of parameters which result in optimal performance of encrypted video in terms of video latency; compare the latencies of encrypted and unencrypted video streams; compare obtained results to our previously published work . For theScenario based on hardware platform: This scenario is based on a hardware platform, used for running camera client/camera server and encrypt/decrypt applications. This scenario is called symmetrical (Scenario I) for the case when the same equipment was used on both ends of the test setup and called non-symmetrical for the case when different equipment was used on both ends (Scenario II). Detailed results are provided for the symmetrical scenario only, while for the non-symmetrical scenario, the main conclusion and figures are shown.Groups based on encryption string length: Each scenario is further divided into groups based on encryption string length .Cases based on encoding algorithm and transport protocol: Each group consists of four cases which were derived by using different combinations of options for the encoding algorithm (H264/MJPEG) and the transport protocol (TCP/UDP). For each case, a pair of tests were conducted, one without encryption and the other with encryption. For each test, two sets of results were obtained. One set represents video latency, while the other set represents network latency. The configuration without encryption is shown in Two scenarios  were necessary in order to show the portability of the developed system to different hardware platforms. The total number of cases in both scenarios was 20, of which 12 cases pertain to scenario I and 8 cases to scenario II. The total amount of tests and presented data may seem large, but this amount of detail is necessary in order to explore all possible options and the measurements supported by the proposed system. This thorough analysis helps in the conclusions drawn about the best approach.In the symmetrical scenario, two compactRIO devices were used as hardware platforms to run the camera client/camera server together with the encrypt/decrypt application nodes. Here, three groups of tests based on string length (128/256/512 bytes) were used. Both ends of the testing setup were located in Limerick, Ireland for the tests.Comparison can be made based on the mean video latency measurements for secure and insecure video. In most cases, tests with encryption have higher video latency values than the tests without encryption. There are two cases which can be considered the best: Case 5 and Case 6. The difference between encrypted and unencrypted video latency is 1.76 ms (in Case 5) and 3.08 ms (in Case 6). In addition, it is found that when encryption is enabled, cases with MJPEG encoding algorithms perform worse than cases with H264. This can be attributed to the nature of the encoding algorithms, i.e., the amount of data which needs to be encrypted and transferred in MJPEG compared to H264. The worst option to use when encryption is enabled is Case 4. This conclusion is made based on the difference in video latency values of tests conducted with and without encryption.By looking at the network latency information, it is possible to get a deeper insight into the causes of the overall latency of the video. Network latency itself results from several factors: packet processing, egress and ingress delays, packets queuing delay and transmission and propagation delays. However, the measurements presented here correspond to network latency of the packets together with the time taken for the encryption/decryption process. Similarly, for video latency measurements in this scenario, all cases have a mean latency value lower in tests without encryption than in tests with encryption.In this scenario, for each transport protocol and encoding algorithm, six tests were conducted: three tests with unencrypted video streams and three tests using encryption. The difference between the three tests was in the encrypted string length . Although it was not found that the video latency in cases with 128 and 256 bytes string lengths performed worse than the video latency in cases with 512 bytes string length, the option with 512 bytes string length is preferred because of lower count of encryption/decryption calls. Having larger chunks of data is beneficial because of the issue known as the “small-packet problem” for UDP. The TCP protocol implements Nagle’s algorithm which deals with the problem by buffering packets and sending several small packets as one .The equipment configuration, shown in In this paper, full encryption of the video stream was conducted. The stream was encrypted in order to evaluate the security solution in terms of video and network latency and to test its usability in applications, which demand real-time transfer of the video over the Internet.The literature review section has highlighted the latest achievements in several fields, which are related to topics discussed in this paper such as: video latency, video security and latency of secured video as the most important. It is worth noting that no results which could be directly compared to ours were discovered in the literature. The results which were closest to ours were from tests in a LAN, with only network latency measurements. In order to compare the results, the secured video would need to be transferred over the Internet and have the video latency measured.As mentioned earlier, the lowest video latency obtained here was in Case 4 (without encryption) and it had the value of 586.16 ms. The lowest secure video latency measured was in Case 12 . The lowest value of latency for secure and unsecure video were obtained using the combination of MJPEG and UDP. These two cases differ in the length of the encrypted data string. Case 4 pertains to 128 bytes string length and Case 12 is conducted with encryption string length of 512 bytes.When comparing the results presented in this paper to the results published in Ref. , it is nTo further compare the results, it is worth noting that results obtained over the Internet have been taken into consideration. In Ref. , the minResults obtained by using UDP as the transport protocol had lower increase in video latency when compared to results obtained with TCP. The reason for this lies in the difference in UDP and TCP protocol implementations. The UDP protocol does not guarantee the packets delivery and in-order delivery. TCP protocol ensures the guaranteed and in-order delivery. Having all parts of the video stream in the right order is crucial for the video quality. One of the main causes of increased latency with TCP is retransmission. This retransmission occurs whenever a packet or a packet segment is not acknowledged by the destination node. Retransmission happens after a timeout known as RTO (retransmission timeout).When compared to tests without encryption, it was found that introducing AES encryption does not necessarily or significantly increase video latency. This is because of the FPGA-based high speed implementation of the AES core using a BITW approach. The LabVIEW–FPGA-based implementation of 128 bytes and 256 bytes AES was achieved at 200 MHz, while 512 bytes AES implementation was achieved at 160 MHz and throughput achieved for all mentioned block sizes was in the range of Gbps . Adding Full encryption of video streams with real-time requirements was conducted for a remote-control marine-based application with live video feedback to a human pilot. Network and video latencies were measured for different video encoding algorithms and encryption string size settings. In terms of video stream, H.264 and MJPEG encoding algorithms were tested, while the video stream was encrypted with string sizes of 128, 256 and 512 bytes.In order to perform full encryption of the video in real-time, two FPGA-based devices were added to the system. Network traffic (containing a video stream) was routed through these nodes and encrypted/decrypted. It is visible from the presented results that enabling encryption using the BITW technique with AES counter mode (AES-CTR) does not greatly influence performance of the video stream in terms of latency. Although in most tests the latencies were marginally higher with encryption, there were a few cases where it was not the case, which indicates that there are other factors (related to the camera and its output stream) which potentially have greater influence on the latency than the encryption itself. The benefits gained by having an encrypted video stream are numerous (privacy and data protection) and outweigh the costs (latency) of the encryption itself.To avoid or reduce this latency, one of the targets for future work is to integrate the security directly into the camera  and also into the equipment on the receiving end of the stream. However, this approach nullifies the major advantage of realising provision of end-to-end security using a bump-in-the-wire technique where the BITW device can be retrofitted to legacy infrastructure that does not have security capabilities. This BITW retrofitting provides a cost-effective solution for security upgrading of expensive equipment.


In both developing and underdeveloped countries there has been a worrying increase in the number of young people drinking alcohol; this public health problem warrants more research. This multilevel study analyzed the influence of drinking refusal self-efficacy, peers’ motivation, and protective behavioral strategies as predictors of alcohol consumption in a sample of 261 young people arranged into 52 social groups (peers who regularly shared leisure activities). A series of questionnaires were administered individually to evaluate beliefs and behaviors related to alcohol consumption at both individual level  and peer level . The results showed that the individual variable  predicted alcohol consumption behaviors. The multilevel design allowed us to evaluate the direct and moderated effects of peers’ enhancement motivation and protective behavioral strategies on the relationship between self-efficacy and drinking behavior. These results show the importance of developing cognitive, behavioral, and educational intervention programs to increase young people and university students’ confidence and ability to use protective strategies, in order to reduce alcohol use. Drinking alcohol is an accepted social and cultural habit in most Western countries. The Report on Alcohol in the Spanish National Plan on Drugs  noted thThese data underline the need to investigate the possible social and psychological factors related to alcohol use, as well as the strategies and possible interventions. Research has demonstrated that some psychological variables have a strong influence on alcohol consumption: drinking refusal self-efficacy is defined as a belief in one’s own capacity to refuse alcoholic beverages ,5; drinkSelf-efficacy can be defined a person’s beliefs in his or her capacity to perform target behaviors in specific situations . AlcoholHypothesis 1:Individuals with lower levels of drinking refusal self-efficacy will adopt more drinking behaviors.Alcohol use is strongly related to motive for drinking ,22, thesHypothesis 2:Individuals who belong to groups with higher enhancement motivation associated to alcohol consumption will adopt more drinking behaviors.Many studies have highlighted the importance of protective behavioral strategies that can reduce the risks and consequences of drinking alcohol ,28. The Hypothesis 3:Individuals who belong to groups where use of protective behavioral strategies for limiting alcohol consumption is more common will adopt fewer drinking behaviors.There has been very little research on how individual and group-level characteristics interact to influence the drinking behavior of individuals. The few investigations that have carried out multilevel analyses of drinking behaviors have focused on how country-level variables  influence individuals’ consumption of alcohol  or how sThe results of the various investigations ,35 have Hypothesis 4:Individuals with low drinking refusal self-efficacy will adopt more drinking behavior if they belong to a group where use of protective behavioral strategies is at a relatively low level.Hypothesis 5:Individuals with low drinking refusal self-efficacy who belong to a group with high enhancement motivation will adopt more drinking behavior if, in addition, the group norm is for a low use of protective behavioral strategies.Our study analyzed individual  and collective  that influence drinking behavior in young adults who spend their leisure time with a group of peers. The specific aims were (a) to validate a multilevel model of drinking behavior incorporating factors at the individual level  and group level  and (b) to identify predictors of alcohol use in young people at the individual and collective level. In order to achieve these aims, and to test the hypotheses outlined above, we first analyzed the relationship between drinking behavior and an individual-level variable, i.e., self-efficacy. Then we analyzed the relationship between drinking behavior and two collective level variables . Finally, we carried out a cross-level analysis of individual variables and collective factors. All participants were volunteers. They were informed that the data would be analyzed anonymously and that they could leave the study at any time. The “Bioethical and Biosecurity Committee” of the University of Cordoba reviewed and approved the study before it began. As participants were to complete a questionnaire anonymously and there was no possibility of producing personal damage, written consent was not requested; this is in accordance with the regulations of the Spanish Ministry of Science and Innovation.M = 23.53; SD = 2.81). A subsample (n = 52) was studying Educational Psychology at the Faculty of Educational Sciences, University of Córdoba, Spain. The rest of the participants were friends or acquaintances of these students. The sample comprised 261 young people , aged 17 to 26 years  and an individual identification code was created with the number of each participant in each group.Sociodemographic data—age, sex, employment status, and level of education—were collected.Drinking refusal self-efficacy questionnaire (DRSE-RA)—a revised and translated version of the DRSE-RA questionnaire —was usedF  = 3.16; p < 0.01; ICC1 = 0.30; ICC2 = 0.68). Enhancement drinking motivation: As enhancement drinking motivation appears to play a particularly important role in young people’s use of alcohol , the extF  = 2.75; p < 0.01; ICC1 = 0.26; ICC2 = 0.64]. Protective behavioral strategies: We assessed use of cognitive-behavioral protective strategies for avoiding or reducing alcohol consumption using a translation of the relevant seven items from the scale developed by Martens et al. . The scaM = 4.45; SD = 3.27), whereas the number of “drinking days” ranged from 0 to 15 days . The average number of drinks consumed over the three-week period ranged from 0–36  and the type of alcohol consumed varied, with fermented alcohol beverages accounting for 15.1% of drinks consumed, distilled alcohol for 31%, fermented alcohol and distilled alcohol for 44.8% . The two variables related to alcohol consumption  had a high correlation .Drinking behavior: The sample answered questions related to their drinking habits during the previous three weeks  using a F-test, and ICC (Intraclass Correlation index defined as the proportion of variance in the outcome explained by the grouping structure between-group variance) were calculated. According to Hox, Moerbeek, and Van de Schoot [F-test must show statistical significance, and ICC values must have values higher than 0.05, 0.10, and 0.15 to consider a percentage of variance explained by the group as small, medium, or large, respectively. Moreover, in order to test the effect of the studied variables in presence of demographic factors, sex was added as dummy coded covariate at the individual level. Finally, because age is associated with alcohol consumption [Statistical analyzes were calculated with the SPSS program v. 22) . A multilevel model was constructed because the hypotheses referred to two levels. The influences of individual and group variables on drinking behavior were examined. Self-efficacy was measured at individual level (level 1) and enhancement motivation and protective behavioral strategies were measured at group level (level 2). Multilevel analysis is more powerful than a simple hierarchical regression analysis because it enables one to assess how individual- and group-level variables interact to explain behavior at the individual level. Moreover, multilevel models enable one to estimate between-group variance, thanks to their random component, which is not possible with simple hierarchical regression analysis. We needed to show within-group similarity variance in the group-level variables; this was done by calculating intraclass correlations. Data on the group-level variables were collected as individual-level values and then modeled at group level by aggregating the data into the 52 friendship groups. In order to assess whether the data could be aggregated in enhancement drinking motivation and PBS, e Schoot , to aggr2  to determine how much of the total variance in drinking behavior (Alcohol_DB) should be allocated to each level of analysis.Model 0 equations:Level 1:Level 2:We estimated the following three models. The first model (Model 1) measured the effect of drinking refusal self-efficacy ((DRSE) individual-level variable) on drinking behavior  (H1) in the presence of sex as covariate.Model 1 equations:Level 1:Level 2:Model 2 also included estimates of the interactions between the group-level predictors: enhancement motivation  and protective behavioral strategies —with respect to drinking behavior. In addition, the average age of groups (Age) was added as covariate. Sex remained as covariate in the individual level.Model 2 equations:Level 1:Level 2:Model 3 included individual variables, group variables and cross-level, two-way and three-way interactions, in order to test the hypothesis (H4) that protective behavioral strategies moderate the association between drinking refusal self-efficacy  and drinking behavior and the hypothesis (H5) concerning the conditional effect of all the individual- and group-level predictors on drinking behavior. Age and sex were still included in order to test the effects of the variables in presence of those covariates.Model 3 equations:Level 1:Level 2:n = 52) was similar to the rest of the sample (n = 209) with respect to all the variables investigated. The results indicated that the reference group was similar to the rest of the sample with respect to all variables: drinking refusal self-efficacy  = 0.53, ns; Mref = 5.02, SD = 0.68; Mothers = 4.93, SD = 0.79), enhancement motivation  = 0.17, ns; Mref = 2.85, SD = 1.24; Mothers = 2.76, SD = 1.34), protective behavioral strategies  = 0.04, ns; Mref = 2.48, SD = 0.83; Mothers = 2.51, SD = 1.19), and drinking behavior  = 1.15, ns; Mref = 7.67, SD = 5.95; Mothers = 9.05, SD = 8.74).First, several ANOVAs were performed to check that the reference group of students from the Faculty of Educational Sciences  = 11.19, p < 0.001) than those who drank non-alcoholic beverages , fermented alcoholic drinks , and distilled alcoholic beverages . They also reported higher scores for enhancement motivation  = 3.84, p < 0.01) than those who drank fermented beverages . Students who drank non-alcoholic beverages reported higher behavioral protection strategy scores  = 6.03, p < 0.001) than those who drink distilled alcoholic drinks  or a mixture of types of alcoholic beverage . Age was not related to the type of alcohol consumed  = 0.69, ns).Second, a further series of ANOVAs with post hoc Bonferroni tests was used to relate the type of alcohol consumed to the psychosocial variables studied  = 7.53, p < 0.001; M = 5.34, SD = 3.77) and more drinking days  = 30.55, p < 0.001, M = 4.86, SD = 2.46, respectively) than those who drank non-alcoholic beverages  and distilled alcoholic beverages . Regarding the number of alcoholic drinks, those students who drank a mixture of fermented and distilled drinks reported higher scores  = 21.23, p < 0.001; M = 19.88, SD = 16.05 and F  = 20.40, p < 0.001, M = 19.84, SD = 16.03, respectively) than those who drink non-alcoholic beverages , fermented alcoholic drinks , and distilled alcoholic beverages . Consequently, there were differences in the global measure of drinking behavior: students who drank a mixture of fermented and distilled drinks had higher scores  = 23.50, p < 0.001; M = 12.48, SD = 8.87) than those who drank non-alcoholic beverages , fermented alcoholic drinks , and distilled alcoholic beverages .However, in relation with the questions associated to the alcohol consumption , there were differences in the type of alcohol consumed. For example, students who drank a mixture of fermented and distilled drinks reported more partying days  was negatively correlated with drinking behavior  and enhancement motivation  was negatively associated with use of protective behavioral strategies .With respect to hypothesis 1, the descriptive statistics and correlations show that drinking refusal self-efficacy . Approximately 32% of the variance in drinking behavior depended on the peer group to which the individual belonged (ICC = 0.323).Model 0 confirmed the existence of significant variance at group level and at individual level  and peer variables  on drinking behavior. The results provide us with valuable information about moderation of alcohol-related behaviors by peer-level variables. First, we offer a detailed account of the multilevel mechanisms by which drinking refusal self-efficacy  and enhancement motivation and protective behavioral strategies (at group level) affected individuals’ drinking behavior; all the expected relationships and interactions that were confirmed have shown to be maintained in the presence of demographic variables: sex did not predict drinking behavior, but age did. Second, our study revealed that the protective behavioral strategies (a) predicted individual drinking behavior and (b) moderated the relationship between drinking refusal self-efficacy and drinking behavior. Third, our study demonstrated that enhancement motivation moderated the effect of group norms for protective behavioral strategies on the relationship between drinking refusal self-efficacy and drinking behavior.Like previous researchers ,19,20,42We also examined group-level enhancement motivation and group norms for protective behavioral strategies as predictors of drinking behavior, but our data suggest that only protective behavioral strategies influenced individuals’ drinking behavior. We found that individuals in groups where use of behavioral strategies to avoid or limit drinking was common exhibited less risky drinking behavior than those whose peer group tended not to use protective behavioral strategies. In other words, young people’s drinking behavior seems to be influenced by peer pressure, in the form of group norms for use of strategies to limit or avoid alcohol consumption. This implies that programs designed to reduce or prevent alcohol consumption in young people and at-risk individuals should pay special attention to promoting the use of protective behavioral strategies within groups of peers.Regarding the cross-level interaction posited in Hypothesis 4, our results showed that drinking refusal self-efficacy was negatively related to alcohol consumption and that this association was stronger in individuals whose peer group made frequent use of protective behavioral strategies. Moreover, the group norm for use of protective behavioral strategies had a greater effect on individual members’ alcohol consumption in the case of people with low drinking refusal self-efficacy. The drinking behavior of individuals with high drinking refusal self-efficacy level was not affected by whether they belonged to a peer group with a high or low level of use of protective behavioral strategies. Moreover, the results showed that when protective behavioral strategies are higher, both individuals with low self-efficacy and individual with high self-efficacy drink less. In the same way, previous studies have shown that individuals with low drinking refusal self-efficacy who frequently used protective behavioral strategies drank nearly seven times less than those that did not use protective behavioral strategies . Ehret, Finally, in relation to the cross-level interaction posited by Hypothesis 5, our results suggest that in order to reduce their alcohol consumption, individuals with low drinking refusal self-efficacy that belong to groups with a high level of enhancement motivation for drinking need to have peers that make frequent use of protective behavioral strategies. In contrast individuals with high drinking refusal self-efficacy who were part of a peer group with a high level of enhancement motivation were not affected by their peers’ use of protective behavioral strategies. Our findings suggest that peers’ use of protective behavioral strategies has more effect on individuals’ drinking behavior than peers’ level of enhancement motivation. Once again, the role of protective behavioral strategies in programs to reduce alcohol consumption among young people has been highlighted. The seriousness of the issue of young people’s drinking means that there is real need for research that can identify possible protective strategies. The spread of intervention programs that include protective behavioral strategies would decrease the negative impact of alcohol consumption on young people ,48.The main limitations of the study are the sample size, the gender distribution and the data collection by the peers, so our results must be interpreted with caution and should be replicated in a larger sample to improve the analysis’ power. Moreover, because the study is cross-sectional, temporal relationships between exposure and outcome variables cannot be established. Then, further researches should replicate the results in longitudinal studies. It is also necessary to take into account the peculiarity of our study, which analyzes the effect of peers’ variables on alcohol consumption, making impossible a randomly selected sample (the groups must be a group of friends). Therefore, some unmeasured or incompletely adjusted confounders may have biased estimates of association, so our results must be interpreted with caution and should be replicated in studies in which perhaps data should be collected more naturalistically, in places where young people spend their free time together, allowing the randomization of the sample. Another limitation could be the methodology used. In this sense, to remember how many drinks individuals have consumed each day over a 3-week period would be difficult, and this difficulty could have biased the participants’ responses. Maybe in further researches it could be interesting to ask participants to register their drinking pattern for three consecutive weeks. There is also a need for more research analyzing the relationship between the type of alcohol consumed and the pattern of alcohol consumption. Our preliminary analysis showed that participants that drank a mixture of fermented and distilled alcoholic beverages had lower drinking refusal self-efficacy, higher enhancement motivation, and made less use of protective behavioral strategies than age peers with higher drinking refusal self-efficacy. Therefore, the intervention programs to prevent negative consequences of drinking behavior could be centered to give more information about alcohol types, quantity, and consequences, and even skills training at individual- and collective-level, to generate more confidence to refuse alcohol drinking.Although there have been multiple investigations of protective behavioral strategies and alcohol use in young people , it is nIn conclusion, our results suggest that interventions to reduce drinking in young adults should be based around improving individuals’ drinking refusal self-efficacy and promoting the use of protective behavioral strategies at peer group level . Low dri


To achieve long-distance underwater optical wireless communication, a single photon detector with single photon limit sensitivity is used to detect the optical signal at the receiver. The communication signal is extracted from the discrete single photon pulses output from the detector. Due to fluctuation of photon flux and quantum efficiency of photon detection, long-distance underwater optical wireless communication has the characteristics that the link is easily interrupted, the bit error rate is high, and the burst error is large. To achieve reliable video transmission, a joint source-channel coding scheme based on residual distributed compressive video sensing is proposed for the underwater photon counting communication system. Signal extraction from single photon pulses, data frame and data verification are specifically designed. This scheme greatly reduces the amount of data at the transmitter, transfers the computational complexity to the decoder in receiver, and enhances anti-channel error ability. The experimental results show that, when the baud rate was 100 kbps and the average number of photon pulses per bit was 20, the bit error rate (BER) was 0.0421 and video frame could still be restored clearly. Underwater optical wireless communication (UOWC) plays an important role in military, environmental detection, marine exploration and disaster prevention, and has attracted more and more attention in recent years ,2,3. TheVideo communication is an important application aspect of underwater optical wireless communication because of its vivid and picturesque characteristic. Due to fluctuation of photon flux and quantum efficiency of photon detection, long-distance photon counting underwater optical wireless communication has the characteristics that the link is easily interrupted, the bit error rate is high, and the burst error is large. It is necessary to improve the transmission reliability through error correction coding. Traditional video compression standards, such as MPEG or H.26X, use a hybrid coding method combining predictive coding and transform coding to compress video sequences, which make video frames depend heavily on each other ,13. ThusIn 2006, Tao et al. proposed a compressed sensing (CS) theory, which broke through the limitation of traditional Nyquist sampling theorem ,17. AccoIn this paper, to realize reliable video transmission of long-distance optical wireless communication, a joint source-channel coding scheme based on residual distributed compressive video sensing is proposed for the underwater photon counting communication system with high bit error rate. Signal extraction from single photon pulses, data frame and data verification are specifically designed. Experimental results show that this scheme greatly reduced the amount of data at the transmitter, transfered the coding complexity to the receiver, and enhanced the anti-channel error ability.x is sparse signal of N dimensions, Φ is measurement matrix with dimension M × N, and y is measured value. If the signal x has a basic base in a certain domain, e.g., x = Ψα, where α is a sparse signal and Ψ is a sparse matrix with dimension N × N, the mathematical expression becomes y = ΦΨα. In reconstruction process, the value of α is obtained by solving the underdetermined equations, and the signal x is obtained by α. The algorithm is usually solved by Orthogonal Matching Pursuit (OMP) [According to the CS theory, accurate reconstruction of a signal can be obtained by sampling the signal in a small amount, when the signal is sparse or the signal can be sparse under certain conditions. Compressed sensing theory can be abstracted into the mathematical expression it (OMP) , Total vit (OMP) , etc.N dimensions [kΦ is measurement matrix of key frame with dimension kM × N, csΦ is measurement matrix of residual matrix with dimension kM × N, the measurement rate of key frames is kr = k/NM, and the measurement rate of residuals matrix is csr = cs/NM. Assuming that the number of key frames is kn, the number of residuals matrix is csn, respectively. Then, the average measurement rate (AMR) is:Joint source-channel coding scheme based on residual distributed compressive video sensing is shown in mensions . To ensuEach measured value is converted into a data frame for transmission in the underwater channel, and the data frame format is shown in Receiver decodes the received packets and restores the measured value. According to the CRC, the correct measured value is placed in the measurement matrix by the serial number, and the wrong measured value is discarded (assignment 0). The measurement matrix is generated by setting the same random number seed as the sender; it does not need to be transmitted. The measured value matrix and the corresponding measurement matrix can be used to reconstruct the image frame by compression sensing algorithm. The key frames are reconstructed directly. The non-key frames are obtained by summing the reconstructed residual matrix and the key frames. Finally, the reconstructed video frame is restored to the video.Light propagation in water suffers from attenuation through both absorption and scattering, which may cause data loss or bit error. The measured values determined by the distributed compressive video sensing theory are of equal importance. Thus, the reconstructed picture quality at the decoder depends only on the number and correctness of the received measured values, i.e., the impact of any data loss is apportioned to each frame of video. Therefore, the loss of measured values has little impact on the reconstruction quality of the image.The structure diagram of system is shown in The principles of restoring the signal is shown in MSE is as follows:ijf and ij’f represent the original image and the restored image, respectively, and 1 ≤ i ≤ M, 1 ≤ j ≤ M. The expression of PSNR is as follows:Comparing the reconstructed video frames with the original images, the image quality assessment is usually divided into two categories: subjective quality evaluation and objective quality evaluation. Subjective quality evaluation depends on the human eye’s intuitive perception of the image . Objectic is the attenuation coefficient, tP is transmitting power, and L is the longest communication distance.To verify the effectiveness of distributed compressive video sensing coding method in photon-counting underwater wireless optical communication system, we used the standard test video sequences “foreman” and “coastguard” (frame size: 128 × 128) as experimental object, with GOP size = 3. The first frame was a key frame, the second frame and the third frame are non-key frames, and the reconstruction algorithm used TVAL3. As a result of the limited length of the water tank, longer distance communication was simulated by attenuating the power of the LED, and the attenuation in the direction of communication was mainly caused by scattering and absorption. Since the communication rate was low and the communication distance was short, scattering was considered the only cause of attenuation, while other impacts caused by scattering were very small and therefore ignored. Therefore, we did not consider the effect of scattering on this experiment, even though it might be somewhat beneficial when some photons are scattered back to the receiver. Instead, we considered the transmitted power having the main effect on the number of received photons. In addition, we simulated the attenuation of light transmission in water by changing the voltage of the LED lamp. Firstly, we used the standard test video sequences “coastguard” as experimental object. It does not need distributed compressive video sensing coding operation. Video frames data were directly transmitted through the underwater photon-counting communication system after channel coding. Then, video frames were measured by distributed compressive video sensing coding, and the measured values were transmitted through the underwater communication system after channel coding. Finally, video frames were restored by decoding at the receiver. The experimental results show the comparison of the first three frames of “coastguard” at different BER. In To evaluate the image reconstruction performance subjectively at different average measurement rate, the comparison of the first three frames of the “foreman” is shown in As can be seen in The optical signal became extremely weak when it passed through the underwater channel to the single photon detector. Since the communication distance was short and the rate was low, very few photons belonging to the slot of symbol “1” traverses to the slot of symbol “0” due to scattering. The bit error we observed was mainly because the number of photons in the time slot of the symbol “1” was not enough, causing the symbol “1” to be misjudged as “0”. It was somewhat advantageous to identify the symbol “1” if the scattered photons run into the time slot of the symbol “1”. The time slot of the symbol “0” had very few scattered photons. However, the distance between the dark count and the background noise photon was much larger than the threshold we set, thus the symbol “0” was not misjudged as “1”.η = 35%. Effective photosensitive area was a circle of diameter ∅ = 500 μm. To increase the communication distance, a focusing lens with a diameter of 10 cm was placed before the single photon detector. According to the experiments, when the baud rate was 100 kbps and the average number of photon pulses per bit was 20, the bit error rate was 0.0421, and the video frame could still be restored clearly. We calculated the optical power corresponding to 20 photon pulses per bit as The wavelength in our experiment system was 500 nm. The quantum efficiency of single photon detector was In this study, a photon-counting underwater optical wireless communication system was built. To achieve reliable video transmission at high bit error rate, we proposed and testified a joint source-channel coding scheme based on residual distributed compressive video sensing, and the transmitted information was specially designed in data frame. In the experiment, the influence of AMR and BER on the quality of reconstructed video frames was analyzed, and the results verify that, if the measurement rate was large enough, the video frames could be restored clearly in the high bit error rate communication environment. This scheme overcomes the traditional video coding shortcomings, such as large computational complexity, limited storage capacity and high coding complexity. It transfers the coding complexity to the decoder, and reduces the sampled data and the requirement of hardware caching. The experimental results show that, when the baud rate was 100 kbps and the average number of photon pulses per bit was 20, the bit error rate was 0.0421 and video frame could still be restored clearly.


Tenacibaculum maritimum is a significant disease of farmed Atlantic salmon, Salmo salar on the West Coast of North America. Smolts recently transferred into saltwater are the most susceptible and affected fish die with little internal or external clinical signs other than the characteristic small  yellow plaques that are present inside the mouth. The mechanism by which these smolts die is unknown. This study investigated the microscopic pathology (histology and scanning electron microscopy) of bath infected smolts with Western Canadian T. maritimum isolates TmarCan15-1, TmarCan16-1 and TmarCan16-5 and compared the findings to what is seen in a natural outbreak of mouthrot. A real-time RT-PCR assay based on the outer membrane protein A specific for T. maritimum was designed and used to investigate the tissue tropism of the bacteria. The results from this showed that T. maritimum is detectable internally by real-time RT-PCR. This combined with the fact that the bacteria can be isolated from the kidney suggests that T. maritimum becomes systemic. The pathology in the infected smolts is primarily mouth lesions, including damaged tissues surrounding the teeth; the disease is similar to periodontal disease in mammals. The pathological changes are focal, severe, and occur very rapidly with little associated inflammation. Skin lesions are more common in experimentally infected smolts than in natural outbreaks, but this could be an artefact of the challenge dose, handling and tank used during the experiments.Mouthrot, caused by  Tenacibaculum have been associated with this clinical presentation in farmed Atlantic salmon : Tenacibaculum dicentrarchi [Tenacibaculum finnmarkense" [Tenacibaculum maritimum [T. maritimum infections in Atlantic salmon smolts in the Pacific Northwest (British Columbia (BC), Canada and Washington, USA) is different from classical tenacibaculosis (as described above) and is commonly referred to as mouthrot [Oncorhynchus tshawytscha) in the Pacific Northwest appear to be resistant to developing mouthrot [Tenacibaculosis is a disease characterized by frayed fins, tail rot, mouth erosion, and skin lesions that are often ulcerative; it causes significant losses in a number of economically important marine fish species worldwide ,2. Threentrarchi , "Tenaciarkense" –6, and Taritimum . Howevermouthrot –11. Cultmouthrot .T. maritimum infections has not been reported in any other Atlantic salmon farming region even in areas where T. maritimum is present.Mouthrot typically affects smolts recently transferred into saltwater, and has been present in the Pacific Northwest since the late 80s . Due to Cytophaga-like filamentous bacteria associated with areas of ulceration and necrosis often extending into the underlying bone" [Cytophaga-like” bacteria as T. maritimum [The pathology of mouthrot in the Pacific Northwest was first described in the early 90s, before the bacterial agent was identified ,14. Grosng bone" . Major taritimum ,16. Disearitimum .T. maritimum, clinical signs are not exclusive to the mouth; the gills and skin can also be affected [When Atlantic salmon smolts are experimentally bath infected with one high dose of Western Canadian affected . Necrotiaffected ,17 and Caffected . Skin leaffected .T. maritimum kills Atlantic salmon smolts in the Pacific Northwest while only causing very small mouth lesions continues to be a mystery. This study describes for the first time the pathology associated with experimentally induced mouthrot and compares it to what is normally seen in natural outbreaks of this disease. Tissue tropism of the bacteria, using the newly developed real-time RT-PCR is also investigated.The mechanism by which T. maritimum [ompA) gene . An alignment of the ompA gene using available Tenacibaculum spp. sequences in the GenBank and from the T. maritimum strains TmarCan15-1, TmarCan16-1, TmarCan16-5, NLF-15, and Ch-2402 [Prior to this publication, there was only one published real-time RT-PCR assay specific for aritimum . The assaritimum . Howeveraritimum , and rea Ch-2402 ,22  following the manufacturer’s protocol, except that an additional washing step using 100% ethanol was performed prior to air drying the RNA pellet. Extracted RNA was stored at -80°C. All assays were run using an AgPath-ID kit (Thermo Fisher Scientific) with 2 μL of RNA and the standard concentrations of primers (400 nM) and probe (120 nM). Each run consisted of 45 cycles.T. maritimum  that came from natural mouthrot outbreaks on BC Atlantic salmon farms [7 cells mL-1 TmarCan15-1, groups 4–3 and 4–4 with 1.78 x 107 cells mL-1 TmarCan16-5 and groups 4–5 and 4–6 with 8.75 x 105 cells mL-1 TmarCan16-1). Two additional groups of 20 shedders were used as controls (4–7 and 4–8), one bath exposed to 1 L marine broth (Difco 2216) (MB) and the other untouched. 24 hours post-bath infection, 40 smolts (cohabitants) were added to each group. The husbandry conditions are described in Frisch, Småge [Tissue samples from a previously published cohabitation experiment  were useh, Småge  and resuh, Småge  and are The cohabitation experiment was approved by the Norwegian Food Safety Authority (Mattilsynet) under the identification code 16/207694.The mouth and gills of five diseased cohabitants from each group were sampled with the exception of the 2 control groups that had no mortality. The brain, heart, kidney and skin mucus were also sampled from two smolts of each of these groups. At days 7 and 14 post-infection, two randomly selected apparently healthy cohabitants were sampled  from each group. However, due to the rapid mortality in groups 4–5 and 4–6, this was not possible in these groups. The day 7 samples in group 4–2 were also missed. All samples were collected aseptically and kept on ice and then stored at -20°C. Moribund smolts and randomly selected cohabitants were euthanized with a swift blow to the head.CCCCTCCAGGACGTTTACAAA, reverse primer: CACACGGCCCACAGGTACA, probe: ATCGGTGGTATTGGAAC) [Halobacterium salinarum DSM 3754T cells suspended in PBS prior to the RNA extraction. This exogenous control was detected using the Sal assay  [RNA was extracted from each of these samples and screened using the Tmar_ompA assay using the above protocol. An assay targeting the elongation factor 1 alpha (EF1A) was used on the mouth, gills, brain, heart and kidney samples as an endogenous control (forward primer: TTGGAAC) . Due to CAGCGGA) .T. maritimum [Representative tissues from the lesions  of diseased fish sampled from Atlantic salmon smolts bath infected with BC strains of aritimum  were fixTissues (mouth and skin) from experimentally infected smolts were also selected for scanning electron microscopy (SEM) examination. Preparation of tissues for SEM was performed as described in Småge, Frisch .T. maritimum based on the testing of RNA extracted from the T. maritimum strains  and RNA extracted from other Tenacibaculum species . When compared to assay developed by Fringuelli, Savage [T. maritimum culture (TmarCan15-1) and 1.9386 for T. maritimum positive skin tissue  of the fish infected with TmarCan16-1 had a lower load of  disease  with les disease . This re species ,35,36. D species . FurtherT. maritimum [T. maritimum strains associated with the different pathological presentations, but it could be due to other factors, including host and environment. One possibility is that the experiments were conducted at different temperatures, 12°C in our study and around 18–20°C in the experiments in Tasmania [in vitro with M. viscosa, a different skin pathogen of Atlantic salmon [The pathology in this study is different to what has been described in both experimentally and naturally infected farmed Atlantic salmon smolts in Tasmania, Australia with aritimum . In Tasmaritimum ,17. The Tasmania ,37. Pathc salmon .T. maritimum kills smolts in the Pacific Northwest still remains a mystery. The main pathology in experimentally infected smolts with Western Canadian T. maritimum strains are mouth lesions that damage the tissues surrounding the teeth causing a disease that is similar to periodontal disease in mammals. The pathological changes are focal, severe, and occur very rapidly with very little associated inflammation. T. maritimum is detectable internally by real-time RT-PCR and bacteriology, and one possible point of entry would be the teeth.The mechanism by which S1 TableCt values of the specificity and efficiency analyses performed during the development of the Tmar_ompA assay.(XLSX)Click here for additional data file.S2 TableCt values of the real-time RT-PCR analysis performed on diseased and non-diseased cohabitants.(XLSX)Click here for additional data file.


To assess drinking occasions (volume and type) according to consumption with food in or outside meals, and location, for six countries.A total of 10,521 participants aged 4–65 years from Argentina, Brazil, China, Indonesia, Mexico and Uruguay completed a validated 7-day fluid intake record. For each drinking event, the volume consumed, the fluid type, the location of intake, and whether the drink was accompanied by food  or not, was recorded.Similar drinking behaviors were found in Mexico and Argentina; fluid intake during meals was 48 and 45% of total fluid intake (TFI), respectively. In Brazil (55%), Indonesia (58%) and China (66%) most fluid was consumed without food. In Uruguay, 34% of TFI was with a main meal, 31% with food between meals and 35% without food. Indonesia had the highest median (25–75th percentile) TFI; 2520 (1750–3347) mL/day, and China the lowest 1138 (818–3347) mL/day. Water was consumed with meals for 37% of Chinese and 87% of Indonesian participants, while the four Latin-American American countries showed a preference for sweet drinks; 54% in Mexico, 67% in Brazil, 55% in Argentina and 59% in Uruguay. Diversity in fluid type was noted when drinking with food between meals. Apart from China, most drinking occasions (> 75%) occurred at home.Three distinct drinking behaviors were identified, namely, drinking with meals, drinking as a stand-alone activity, and a type of ‘grazing’  behavior. Most drinking occasions occurred at home.The online version of this article (10.1007/s00394-018-1744-8) contains supplementary material, which is available to authorized users. Recent interest in the effects of hydration on health and disease –4 has reIncreasingly, food and drink are being consumed outside the home. For example, in the USA, expenditure on food away from home increased from nearly 26% of total expenditure in 1970 to 43% in 2012 . This isDrinking behavior, like eating behavior, is influenced by many factors including culture, religion, familial and peer influences, socioeconomic status, geographic location, taste preferences, etc. –16. ReseWhile some studies, particularly national diet and nutrition surveys, e.g., Kerr et al. , report The recruitment of participants and further details of the populations included in this analysis have been described previously –33.Liq.In7 record; a 7-day fluid-specific record validated for accuracy and reliability [Liq.In7 record was presented in the official country language. The record had the same structure and content in all countries; this was adapted according to the brands available in each country. The record was delivered and explained to the participants during an interview at home. After a period of 7 days, the paper record was collected by the researcher and checked with the participant for completion. An electronic version of the record was used in China. The Liq.In7 record was structured according to occasions during the day, namely, awakening, meal times , periods between meals  and during the night. The participants were instructed to report all drinking events at any moment of the day with the following details: fluid type, size of the container from which the fluid was drunk, actual volume consumed, where the consumption took place and if the fluid was consumed with or without food. Liq.In7 does not record food consumption. To assist the participants in estimating the precise volume of fluid consumed, a photographic booklet of standard fluid containers supported the records. For children younger than 12 years, the primary caregiver was responsible for completing the record.Participants were provided with the iability . The LiqCharacteristics of TFI and consumption of different fluid types in the six countries are discussed further in other articles –33. The Participants were given detailed information about the survey’s objectives, their involvement, their rights to confidentiality, risks and benefits, and a clear explanation that participation in the survey was entirely voluntary. All participants gave informed oral consent and no monetary incentive was offered to take part in the survey. All data were recorded and analyzed anonymously. The survey protocol was reviewed and approved by the University of Arkansas Review Board (ref. 14-12-376).Liq.In7 record, those who reported a mean total daily fluid intake < 400 or > 4000 mL/day for children younger than 14 years and > 6000 mL/day for participants older than 14 years were excluded from the analysis. Due to the skewed distribution in intakes, TFI per drinking occasions and location are presented as medians and 25–75th percentiles as well as mean and standard error of mean. The intakes of the different fluid types are reported as median (25–75th percentiles). The mean and standard error of mean (SEM) of the fluid types can be found in the Online Source Tables S1a–c. As there were limited and inconsistent gender differences, these data are not presented according to gender.Participants who did not complete the full 7 days of the The drinking occasions were classified into three categories (1) “meals” meaning that the act of consumption was during a main meal, (2) “outside of meals” meaning that the act of consumption was taken with food but not during one of the main meals, and (3) “without food” meaning that the act of consumption was taken without any food .Locations of consumption were categorized for analysis into the following categories; at home, at school/work/university, including cafeterias, and all other locations, e.g., restaurant/bar/public house, transportation, friend/acquaintance’s house, sports venue, shopping center, street, park, hotel, hospital. The variable “location” was not completed for all fluid intake acts, and these are reported in the online resources as “Unspecified”.The demographic characteristics of study population aged 4–70 years  for each of the six countries are shown in Table Table Table There was more diversity in the fluid types consumed with food outside of meals. In Mexico and Brazil sweet drinks  remained the most popular drinks when eating food outside of meals . In Argentina and Uruguay participants most frequently drank hot beverages  on these occasions. Water was the most popular drink taken with food outside of meals in China (44%) and Indonesia (64%); however, 25% of fluid intake at these occasions in China was SSBs.The most popular stand-alone drink (without food) was water with median (25th–75th percentiles) intakes ranging from 109 (0–336) mL/day in Uruguay to 1101 (585–1749 mL/day) in Indonesia. However, when expressed as percentages, water constituted 36% of fluid intake consumed without food compared with 40% for hot beverages. Data for each age category, by country, are shown in the Online Source Tables S4a–c.In all countries except in China, most drinking occasions (over 75%) occur in the home Table . In ChinTable This study is the first time that drinking behavior, in terms of volume and fluid type, has been reported for these populations by including whether or not food was also consumed, either as a meal or outside of meals. We describe three distinct drinking behaviors: drinking with meals, drinking as a stand-alone activity and a type of ‘grazing’  behavior, which appear to be linked to social, cultural and dietary factors. This hypothetical link is based on the clear differences observed between countries. No comparable studies are available for Argentina, Brazil, Mexico, Uruguay or Indonesia, although there have been reports on drinking occasions from China. A study in schools in China showed that 71% of TFI are consumed outside meals , which iChinese, Indonesian and Brazilian participants most frequently consumed fluids without food, while Mexican and Argentinian participants favored drinking with food, both during and between meals. The participants from Uruguay drank throughout the day, a behavior that may be described as ‘grazing’. Mate, a traditional hot infusion of the herb Ilex paraguayensis, is popular in Uruguay  and is cWater was the preferred drink when no food was eaten in all countries included in this study, except for Uruguay, which favored hot beverages, probably mate. However, there was more variation in the preferred type of drink when eating between meals. Eating food appeared to be a major determinant of fluid type choice especially during meals. To the best of our knowledge, only two other studies (both in children aged 4–17 years) have described the type of beverages according to meals and between meal occasions. A study of British children aged 4–13 years showed that 60% of fluids were consumed at meal times and that the drink of choice varied over the course of the day . At breaIt is interesting to note that terminology has an impact on whether or not fluids are included in studies. For example, definitions of an eating occasion, a meal or, in particular, a snack vary and are often based on the energy contents of the snacks . This maMost drinking occasions occurred at home for all of the Latin-American countries and Indonesia; in China less than half of the TFI was consumed at home. Similarly, it was found that for French children  most driThe present study has several strengths, not least the use of a validated methodology that captures all drinking occasions . In addiIn conclusion, this is the first study to report drinking behavior in relation to eating occasions and location using harmonized and validated methodology. This study showed clear differences between countries and identified distinct drinking behaviors. These behaviors suggest that eating food was associated with the choice of fluid type. Further studies are needed to explore reasons for differences in drinking behavior, especially cultural factors. Understanding drinking habits is particularly important given the increasing recognition of the role of healthy hydration in the prevention and management of several diseases, including cardiometabolic and renal conditions. In particular, understanding drinking habits in terms of location should inform the rationale for further public health programs and policies. As such, culturally, and country-specific interventions will be more relevant to the targeted population and, therefore, hopefully more effective.Below is the link to the electronic supplementary material.Supplementary material 1 (DOCX 239 KB)