Radiosurgery by Gamma Knife (GK) is an effective treatment for brain arteriovenous malformations (AVM). The aim of the present study was to evaluate late, radiation-induced changes detectable by MRI after AVM radiosurgery in patients treated minimally 10 years prior, with AVM obliteration proven by angiography.Thirty-five patients with 37 AVMs were included. AVMs were irradiated 16.6 ± 3.5 years prior with AVM obliteration proven 13 ± 4 years prior. All patients underwent recent MRI examinations, including application of gadolinium-based contrast. p = 0.004). Enhancement was not influenced by total radiation dose, patient age at the time of irradiation, duration since radiosurgery, or the number of irradiations. Wallerian degeneration was found in nine of 37 cases (24 %); in six cases the optical tracts were affected and visual field defects were proven. In five of nine cases (55.6 %) with Wallerian degeneration previous hemorrhage was present. Dual vascular pathology was found in eight of 35 patients (23 %).In one case, post-irradiative cystic formation with mass effect and signs of hemorrhage requiring surgery was found. Post-gadolinium enhancement at the site of obliterated nidi was apparent in 28 of 37 cases (76 %). In all cases except one, the mean volume of enhancement at the time of review was clearly lower than the volume of the originally irradiated AVM ; in one case the extent was 142 % greater than the irradiated AVM. When we compared enhancing and non-enhancing nidi, we found that enhancing nidi were significantly larger than non-enhancing nidi at the time of radiosurgery (4.39 ± 3.35 cc vs. 0.89 ± 0.79 cc,GK radiosurgery for AVM is a safe treatment method although delayed complications may occur. Post-gadolinium enhancement of obliterated nidi may indicate an active post-irradiative process. Arteriovenous malformations (AVM) in the brain are characterized by a conglomerate of tortuous vessels with feeding arteries and draining veins. These vessels shunt directly from the arterial to the venous system; normal intervening capillary networks are absent. Additionally, the endothelial cell layer in AVMs structurally differs from normal cerebrovascular endothelium . HemorrhWe have provided stereotactic radiosurgery for the treatment of AVM at our institution since 1992. We use digital subtraction angiography (DSA) and magnetic resonance imaging (MRI) for the stereotactic localization of AVMs. First MRI follow–up is standardly performed 2 years after radiosurgery. After the disappearance of flow voids on MRI, DSA is indicated to prove complete AVM obliteration. In the case of suspected complication, computed tomography (CT) or MRI is performed to exclude re-bleeding or postirradiation edema. Once complete obliteration of the AVM is verified by DSA, only symptomatic patients continue to be followed actively at our institution.It has previously been reported that AVM obliteration was achieved in 74 % patients after the first round of radiosurgery and in 69 % of remaining patients after a second round of radiosurgery [Although stereotactic radiosurgical treatment for AVM is a well-established method, delayed, long-term postirradiative changes on MRI after GK treatment have not been sufficiently investigated. In the present study, we evaluated late radiation-induced changes on MRI following radiosurgical AVM treatment in a group of patients treated between the years of 1993 and 2005 in whom complete AVM obliteration was proven by DSA, with no symptomatic complications since.We examined all available medical records of patients treated by GK radiosurgery for AVM between the years 1993 and 2005. In this period, 675 patients were identified. They came from the region of former Czechoslovakia and also abroad. Only patients living in the vicinity of our facility were selected for accessibility purposes. We further excluded all patients who underwent open surgery following GK radiosurgery failure, as well as patients with severe disabilities, pregnant or lactating women, and patients older than 70 years. One hundred and eight patients were contacted by phone or by mail and offered a follow-up MRI examination with gadolinium-based contrast. The study was approved by the local ethics committee and all participants provided written informed consent.Patients that underwent their first radiosurgical procedure for AVM between the years 1993 and 2005  by Leksell Gamma Knife . Patients that underwent a second or third radiosurgical procedure 3 years after the first procedure due to patent AVM were also included.Complete obliteration of the AVM proven by DSA.Age under 70 years, not pregnant, not lactating, and in good health.No contraindications to MRI.Summary of the inclusion criteria:TSE T2/PD transversal scans FLAIR FAT-SAT transversal scans T2 SWI 3D transversal scans GE T1 coronal and transversal scans SE T1 sagittal scans DWI FAT-SAT transversal scans GE T1 3D after gadolinium intravenous administration .All patients underwent MRI examinations. MRI was performed using a 3T whole-body MRI scanner  fitted with a 32-channel head coil. The MRI protocol included the following sequences and parameters:Volumetry of the enhancing AVM nidus was performed, when present. Volumes were segmented manually and calculated with software developed on in-house for a standard work console.A.Cyst formation was considered relevant in cases where minimally one of the following was present: mass effect, high protein content, perifocal vasogenic edema, cyst wall enhancement. Post-hemorrhagic pseudocystic changes with cerebrospinal fluid content, without enhancement and without mass effect were considered as insignificant post-hemorrhagic changes.Presence of post-gadolinium AVM nidus enhancement including volumetry.In–field changes (in the field of radiosurgery)B.Presence of Wallerian degeneration due to irradiation or complication of hemorrhagic AVM.Out-of-field changesC.Presence of vascular or other dual pathology on MRI.Dual pathology elsewhereThe defined endpoints of interest were as follows: t tests; categorical values were analyzed using the Chi-square test; p values ˂0.05 were considered significant. Analyses were performed using STATISTICA software, vers. 12.Data were expressed as mean ± SD in variables with Gaussian distribution and as median. We analyzed various potential effects on post-gadolinium nidus enhancement by means of unpairedThe patient response rate was 32.4 %. Thirty-five patients  met the inclusion criteria and were included in the study; mean age of included subjects was 49.4 ± 12.4 years . The AVMs were irradiated 16.6 ± 3.5 years  prior; AVM obliteration proven by DSA performed 13 ± 4 years  prior. Thirty-seven AVM nidi in 35 subjects were irradiated (two patients with two AVMs). AVMs were graded according to the Spetzler–Martin AVM classification [Only one  serious late complication requiring urgent surgery was found on MRI; it was a post-irradiation cyst formation with mass effect and signs of hemorrhage. For more details, see the case report below.We found next 12 pseudocysts with hemosiderin rim surrounded by gliosis, with cerebrospinal fluid content. Eleven of those pseudocysts were present on MRI before GK treatment; all those AVMs manifested as intracranial bleeding. In one patient, clinical symptomatic bleeding was present 1 year after irradiation, since that time pseudocystic changes were present. Those cases were considered as irrelevant post-hemorrhagic pseudocystic changes.Post-gadolinium enhancement of the obliterated AVM nidus site was apparent in 28 of 37 cases (76 %). In only nine of 37 (24 %) cases, enhancement of the AVM nidus site was not detectable after intravenous contrast administration. In all cases except one, the mean volume of enhancement was clearly lower than the volume of the irradiated AVM. The extent of enhancement was approximately 88 ± 20 % (median 92 %) less than the volume of originally irradiated nidus. In one case, the extent of enhancement was clearly greater than the irradiated nidus roughly 142 %) and was surrounded by irregular deposits of hemosiderin, although the patient did not suffer from hemorrhage before radiosurgery or at time of the last MRI follow-up 15 years prior. The MRI appearance in this case resembled cavernous malformation . For more details, see Table p = 0.14, Chi-square test).Enhancing nidi were significantly larger than non-enhancing nidi at the time of irradiation  than nidi smaller than 5.00 cc, in which hemorrhage prior to radiosurgery was detected in 54.2 % . In six cases, the optical tracts were affected . In one case, the pyramidal tract was degenerated ; in four subjects arterial aneurysms, in two subjects cavernous malformations, and in two patients venous angiomas were detected. Non-vascular dual pathology was detected in two patients (low-grade glioma in one patient and multiple metastases from breast carcinoma in one patient). Multiple metastases were found at time of the late review and the patient was immediately sent for oncological treatment. In the second case, the presence of low-grade glioma was known since the time of AVM diagnosis. The patient was sent for MRI after the first generalized epileptic seizure; AVM in the left occipital lobe and low-grade glioma in the right frontal lobe was found. In the same year, the patient underwent neurosurgical resection of the glioma and radiosurgery for the AVM. At time of the late review, the patient was asymptomatic , and the AVM was irradiated by a maximum dose of 50 Gy with a marginal dose of 25 Gy. One year later, DSA follow-up showed complete obliteration of the AVM. The patient did not suffer from any clinical manifestations and therefore follow-up at our institution was terminated; he was advised to continue follow-up with his local neurologist. Twenty years later, he agreed to participate in the present study. MRI revealed cystic changes measuring 44 × 51 × 39 mm in the right frontal region, with defiguration of the frontal horn of the right lateral ventricle and slight midline shift. Signs of repeated hemorrhage with fluid–fluid level were observed  were included who were treated by radiosurgery 16.6 ± 3.5 years prior to study onset, with AVM obliteration proven 13 ± 4 years prior. We found only one case (2.7 %) of serious late post-irradiative complication; a large cystic mass with high protein content and an enhancing wall. This patient required open surgery. Cyst formation is a rare but well-documented complication following radiosurgery for AVM , 13. ItsAccording to previous reports, there are two types of cystic formations: chronic encapsulated expanding hematoma, and cysts with a neo-angiogenetic nodule in their wall. Common etiological mechanisms have been suggested for both types of lesions . The devIn the present study, we found that most obliterated nidi  still clearly enhanced after intravenous gadolinium contrast administration, 16.6 ± 3.5 years after GK radiosurgery. This is in agreement with a similar study conducted by Kihlstrom et al., where 61 % of obliterated nidi enhanced after contrast administration . They ex p = 0.004). However, enhancement was not influenced by total radiation dose, patient age, or duration since GK radiosurgery. We also did not find any statistical differences between postgadolinium nidi enhancement in subgroups AVM nidi irradiated once and more than once (two or three times). We found that nidi larger than 5.00 cc were associated with significantly less pre-treatment hemorrhage (12.5 % nidi) as opposed to nidi smaller than 5.00 cc (54.2 %). Similar findings have been described previously [When we compared enhancing and non-enhancing nidi, we found that later enhancing nidi were significantly larger than non-enhancing at time of radiosurgery . Typically, the optical tracts were affected in cases where the irradiated AVM was situated in temporal or occipital lobes. These patients suffered from visual field defects. Wallerian degeneration is a complication of GK radiosurgery that has received little attention previously . HoweverOur study has several important limitations. First, not all patients treated between the years 1993 and 2002 could be evaluated; the patient response rate was only 32 %. Most patients were lost to follow-up while only some refused to participate in the study. Due to the low response rate, it is difficult to assess sensitivity of the MRI findings. We could speculate that the low response rate may be partially due to good medical condition of the patients or on the contrary due to bad health. Some patients probably died. Also, in some older cases, medical documentation was not complete. We included patients irradiated only once, as well as those who underwent 2–3 irradiations. This approach may have resulted in some bias. However, we did not observe significant differences in the proportion of postgadolinium enhancement between these two subgroups.In conclusion, GK radiosurgery for AVM is a safe treatment method, although delayed complications cannot be avoided and were found 16.6 ± 3.5 years after therapy. Additionally, post-gadolinium enhancement could be a sign of an active, delayed post-irradiative process.


Despite frequent primary care visits, older veterans may have unmet behavioral health needs regarding alcohol misuse. Identification of alcohol misuse and referral of older veterans seen in primary care to behavioral health care can decrease at-risk drinking and assist in determining effective interventions for older veterans with problem drinking. This study examined the effect of integrated and enhanced referral behavioral health models on alcohol misuse among older veterans.This was a secondary analysis of data collected at five Department of Veteran Affairs (VA) Medical Centers as part of the Primary Care Research in Substance Abuse and Mental Health for Elderly study, a multisite randomized controlled trial. The sample included 1222 older male veterans who were randomly assigned to integrated or enhanced referral behavioral health care at VA primary care clinics with 6 to 12-month follow-up. Brief alcohol treatment was provided to at-risk drinkers by behavioral health providers either co-located within primary care clinics (integrated treatment model) or a separate location offering transportation assistance and coordinated care between behavioral health providers and primary care physicians . Alcohol misuse included both at-risk drinking for older adults (> 1 drink daily) and problem drinking assessed using the Short Michigan Alcoholism Screening Test-Geriatric Version (problem drinking ≥ 3 affirmative responses). Both behavioral health models required a minimum of one treatment session, with no maximum number of sessions over a 6-month period. After 6 months, attendance at treatment sessions was voluntary.At baseline, 35.8 percent (n = 438) reported at-risk drinking and of those, 46.1 percent (n = 200) reported problem drinking. At 6 months, 21.1 percent (n = 234) reported at-risk drinking and of those, 41.4 percent (n = 150) reported problem drinking. At 12 months, only 36.3 percent (n = 89) reported problem drinking. Bivariate analyses revealed no significant differences between behavioral health models in at-risk and problem drinking over time. Generalized linear mixed modeling revealed treatment and time effects were significant for at-risk drinking after controlling for VA site, race, education, employment, and depressive symptoms. Treatment and time effects were significant for problem drinking after controlling for VA site, race, and depressive symptoms. The treatment x time effect was non-significant for at-risk and problem drinking.Both integrated and enhanced referral behavioral health models were effective in reducing at-risk drinking among older male veterans seen in VA primary care clinics with follow-up over 12 months. However, the integrated model was more effective than the enhanced model in reducing problem drinking. Screening and brief intervention for alcohol misuse in primary care can be cost effective by reducing service utilization and potentially result in a medical cost offset. Based on primary care protocols, VA health administrators and policymakers should determine which treatment model is best for their patients, providers, and infrastructure. Future research should examine treatment processes of both behavioral models to determine their effect on alcohol misuse in older veterans.


N = 607) classified as pathological gamers. Study 2 replicated and extended the findings of Study 1 with college undergraduates (N = 504). Predictive validity was established in Study 3 by measuring cue reactivity to video games in college undergraduates (N = 254), such that pathological gamers were more emotionally reactive to and provided higher subjective appraisals of video games than non-pathological gamers and non-gamers. The three studies converged to show that pathological video game use seems similar to other addictions in its patterns of correlations with other constructs. Conceptual and definitional aspects of Internet Gaming Disorder are discussed.Three studies assessed the construct of pathological video game use and tested its predictive validity. Replicating previous research, Study 1 produced evidence of convergent validity in 8th and 9th graders ( Changes in technologies bring the potential for changes in users’ thoughts, feelings, and behaviors . ConsequThe difficulty of defining problem video-game playing as an addiction mostly arises because video-gaming does not involve a chemical substance and because problems created by heavy use of video-games tend to be more benign as video-game playing is less likely to pose social threats through illegal activities, compared with drug addiction . AlthougFrom the experiences of clinical colleagues and increasing media reports, it appears that a number of gamers demonstrate symptoms of pathological computer and video game use ,22. AlthSubstance abuse and pathological gambling are often associated with antisocial personality disorder or aggressive behaviors . Given Studies could also test the construct in other ways. For example, few studies have provided evidence of predictive validity, and the bulk of these studies have focused on predicting future addiction to video game play . To testThe purpose of the present research was to test empirically the correlates and predictive validity of pathological video-gaming based on DSM-style criteria for pathological gambling. Three studies were conducted. Two correlational studies tested the construct of pathological video-gaming by comparing associations between it and other psychological traits, such as aggression and hostility, in samples of young adolescents in the 8th and 9th grade (Study 1) and older adolescents (Study 2). In Studies 1 and 2, we hypothesized that pathological gamers would show higher trait hostility, and higher antisocial and aggressive behaviors than non-pathological gamers. Study 3 was a quasi-experimental study that examined changes in emotional status before and after exposure to video games and appraisal of games played to test the predictive validity of pathological gaming, based on the concept of cue reactivity. The data in these three studies were collected prior to the publication of the DSM-5, although all three studies used scales designed to be similar to the DSM.N = 496) and 9th-grade (N = 111). Students were recruited from four Midwestern schools, including one urban private school (N = 61), two suburban public schools (N = 350), and one rural public school (N = 196). Students were recruited from mandatory classes within their schools, and participation was greater than 90% in all classes. The mean age of respondents was 14 years (SD = 0.64). Fifty-two percent of the participants were male. Eighty-seven percent of the respondents classified themselves as Caucasian, which is representative of the region of the country in which they reside. Participants were asked to report their frequency of playing video games on a scale from 1 (I never play video games) to 10 . Non-gamers were identified as those who reported never playing video games (n = 37); remaining participants were classified as gamers (n = 569) with one missing value. Analyses are conducted on gamers. All participants were treated in accordance with the ethical guidelines of the American Psychological Association (APA).Data were collected from 607 young adolescents  in 8th-grade , a confidential survey that gathered data about students’ media habits, attitudes, knowledge about video games, and pathological video gaming as well as school performance and demographic data ,33. The Key variables in this study include pathological video gaming, personality trait hostility, hostile attribution bias, antisocial and aggressive behaviors, and preference for violence. Each variable was measured as follows. Seven items from the GMHQ assessed pathological gaming. These items were modifications of the DSM-IV criteria for pathological gambling, . The inAntisocial behavior was measured by asking how often the participants had gotten into arguments with their parents, friends, and teachers in the past year. Responses were given on a 4-point Likert-type scale (ranging from “Less than monthly” to “Almost daily”).Participants were asked if they had been in a physical fight in the last year. This question yielded a dichotomous response (yes/no).Participants were also asked to indicate how much violence they prefer to have in their video games on a 10-point scale , and how much violence they prefer to have in their video games compared to 2–3 years ago on a 5-point scale . n = 69) were considered pathological video-gamers as defined by reporting over half of the symptoms. As expected from the prevalence of pathological gambling and substance addictions, males were more likely to be pathological gamers than females. For young adolescents, the prevalence rates were similar to pathological gambling prevalence rates. For male gamers, 16% met the criteria for pathology (48 out of 306) while 7% of females met these criteria . Overall, participants spent a typical amount of time playing video games for this age group . However, pathological gamers averaged 21.6 hours/week (SD = 19.6), whereas non-pathological gamers averaged 7.9 hours/week (SD = 9.7).It was predicted that pathological gamers would show patterns of correlations similar to those seen in other pathologies, including higher levels of antisocial behavior, hostility, and aggressive behavior. To this end, an analysis of covariance, controlling for gender, was conducted on these outcomes.2= 6.6, df = 1, p < 0.05, n = 567). They also reported significantly higher preference for violence in video games than non-pathological video-gamers. Due to the use of multiple tests, a conservative approach of using Bonferroni corrections was applied requiring a significance threshold of p < 0.004, which resulted in one test (arguments with parents) dropping below the significance threshold. As displayed in the upper part of Study 2 was designed to replicate and extend Study 1 by using a different population (older adolescents who were undergraduates), by using some different measures, and by modifying the pathological video-gaming criteria. We again hypothesized that pathological gamers would show higher trait hostility, and higher antisocial and aggressive behaviors than non-pathological gamers. It is, therefore, a conceptual replication of Study 1, and would allow for greater generalizability of the data if the results were similar.n = 38). Ninety percent of the respondents classified themselves as Caucasian, which is representative of the region and university population. All participants were treated in accordance with APA ethical guidelines.Data were collected from 504 undergraduates  enrolled at a large Midwestern university. Students voluntarily participated and earned extra credit points for their introductory psychology classes. Gamer status was measured similarly to Study 1. Again, analyses exclude non-gamers (Each participant completed three surveys: (1) scales from the adult version of the General Media Habits Questionnaire (GMHQ) that gathered descriptive data about students’ video game habits including pathological video-gaming and demographic data; (2) a survey of aggressive and prosocial behaviors; and (3) a measure of trait hostility. Participants completed the surveys in a large group setting. The measures were embedded in a battery composed of various survey instruments submitted by several independent researchers. Pathological video-gaming was measured similar to the approach described for young adolescents, except that nine items were used and participants were only able to answer “yes” and “no” without the option of “sometimes” to make the scale more similar to DSM  criteria. Participants were considered to be pathological gamers if they answered yes to five or more items, again based on DSM approaches to requiring at least half of symptoms to be present. Reliability was acceptable (α = 0.73). The Buss-Perry Aggression Questionnaire  was usedStudents completed the Social Interaction Survey , which mIdentical to the approach described in Study 1.n = 30). For male undergraduate gamers, 9% met the criteria for pathology (29 out of 309) while 0.5% of females met these criteria (1 out of 195). Overall, participants spent a typical amount of time playing video games for this age group . However, pathological gamers averaged 17.6 hours/week (SD = 12.74), whereas non-pathological gamers averaged 8.19 hours/week (SD = 9.40).An analysis of covariance, controlling for gender, was used to examine the relations between pathological gaming status and several outcomes. Across measures, pathological older adolescents showed similar patterns of association with antisocial and aggressive traits and behaviors to those shown among younger adolescents , althougp < 0.004. This resulted in all tests except for reactive relational aggression dropping below the significance threshold.Pathological gamers scored higher than non-pathological gamers on the Buss-Perry trait hostility scale, though this difference was only marginally significant after controlling for gender. Pathological gamers scored higher on each of the subscales of the Buss-Perry although only the verbal aggression subscale reached the significance threshold and hostility was marginally significant. Pathological gamers were more likely to report being more proactively and reactively relationally aggressive. They were also more likely to report being proactively physically aggressive. The relationships between pathological status and reactive physical aggression, as well as helping behavior, were both in the predicted directions but neither relationship was significant after controlling for gender. Pathological gamers also reported significantly higher preference for violence in video games than did non-pathological video-gamers, as found in the sample of young adolescents. These results provide a strong conceptual replication of Study 1, given that the same pattern of results was found despite using a different age population and different measures of hostility and antisocial and aggressive behaviors. Again, a conservative approach to examining multiple tests involved the application of Bonferroni corrections, requiring a significance threshold of Study 3 was designed to test the predictive validity of pathological gaming status. In Study 3, undergraduates played three video games and rated them on several dimensions as well reporting their emotional states prior to and immediately after playing the games. As described earlier, we hypothesized that pathological gamers should show heightened reactivity to video games if the measure of pathological video-gaming has predictive validity. The sample consisted of 254 undergraduates  at a large Midwestern university. Participants earned extra credit for their introductory psychology classes for participating in the study. Fifty-two percent of participants were male. Race information was not collected, but is likely to approximate 89% Caucasian as in Study 2. All participants were treated in accordance with APA ethical guidelines.The study included aspects of both between-subjects and within-subjects designs. When participants arrived to the lab they completed an informed consent document and the GMHQ. Participants were randomly assigned to play three video games for 20 minutes each. Prior to playing each game participants completed the state emotion scale. Following each game, participants again completed the state emotion scale and a video game evaluation. Participants were debriefed and given credit. Pre-post game play emotional change scores were created for each participant. For this study, the critical tests were between pathological gamers, non-pathological gamers and non-gamers.Video games. Nineteen games of varying content  were used in the present study. Sixty-six percent of the games were considered by the experimenters as being non-violent and 34% were classified as violent . Each participant played three of these games, which were randomly selected. The selected three games were not all violent nor all non-violent.n = 34) while males were more likely to be categorized as pathological gamers . Males and females were more equally distributed in the gamer group . Additionally, the test-retest reliability of the measure of pathological video-gaming was possible to evaluate in this study. Our undergraduate samples were free to sign up to participate in either or both Study 2 and Study 3, and 47 students participated in both, allowing for an exploratory look at test-retest reliability of the pathological video-gaming markers. The dates on which these students participated in the experimental study were not recorded, hence the exact test-retest interval cannot be known. The experimental study (Study 3) ran throughout the semester, and the correlational study (Study 2) was conducted on one day about three-fourths into the semester. Assuming a random distribution of participation dates among students who participated in both studies, it is likely that the average test-retest interval was about a month. Test-retest reliability was high; the correlation (r) between the two sums of symptoms was .80 (p < 0.001). The correlation between the two dichotomous pathological video-gaming categories  was also significant, at ρ = 0.55 (p < 0.001). Four participants moved from the non-pathological group to the pathological group in the experimental study. This may be due to three reasons. First, participants had volunteered to participate in a video game study and were given a more comprehensive video game habits survey than participants in Study 2. Therefore, participants answered questions all related to video games and were able to think more carefully about their habits than in Study 2, in which participants answered a battery of questionnaires of many types . Second, it is likely that students were more thoughtful and careful in the experimental study because they were tested individually in their own private rooms, whereas in the Study 2 they were in a room with hundreds of other students where there may be more emphasis on finishing quickly rather than carefully. Third, it may simply be the case that these students developed enough pathological symptoms to be classified as pathological players in the time period between their participation dates. Nonetheless, the test-retest reliability was high. Each participant completed the General Media Habits Questionnaire (GMHQ). Pathological video-gaming was measured the same way as in Study 2. A total of 12 participants met the criteria for pathological gamer status (5%). Among the remaining participants, 203 were categorized as gamers (80%) and 39 were categorized as non-gamers (15%). Females were more likely to be non-gamers  designeetc.) using a seven-point scale (1 = “strongly disagree” to 7 = “strongly agree”). The 14 dimensions are displayed in Participants provided their impressions of the video games played on 14 dimensions  with a chi-square test. This was done for three reasons. First, it confounds any order effects that may be present. From a theoretical perspective, pathological gamers should show higher reactivity regardless of order, whereas non-pathological gamers may have higher responses only to the first game if they were excited to get to play games as part of a study. This approach likely yields lower power to find effects if strong order effects are present. Second, it confounds any effects of the content of the games. Theoretically, violent video games should elicit higher responses for both pathological and non-pathological gamers. Therefore, it is important to eliminate any content-based effects. Third, because this study has a smaller sample, and because inclusion criteria were somewhat more strict compared to Study 1 (the exclusion of a “maybe” option) there were few pathological gamers . Chi square analyses were performed here, rather than the more traditional repeated measures analysis, for two primary reasons. First, both groups suffer from the same independence assumption violation and therefore any error that results from the multiple measurements is applied evenly across groups, thus not prejudicing the results in any particular direction. Secondly, a violation of the assumption of independence ultimately increases the error term by not accounting for the variance that could normally be accounted for if we were conducting more typical repeated measures analyses with parametric data. Therefore, violation of this assumption should serve to prejudice the results against our hypotheses, as statistical power is lost. The data reported here combine responses, resulting in each of the three responses being analyzed simultaneously (etc. the games were to play), but would not be different on objective dimensions .Theoretically, people who are physically or behaviorally addicted should show greater cue reactivity to stimuli that are related to their addiction than non-addicted controls. If pathological video-gaming is similar to other addictions, then pathological gamers should show greater responsiveness to games on several dimensions, including their appraisals of the games as well as changes in their emotional states. With regard to the game appraisals, we had directional hypotheses, predicting higher appraisals than non-pathological gamers on subjective dimensions . In addition, breakdowns of the emotional change scores among pathological gamers with the observed and expected distributions are provided in Prior to and following each game, participants selected emotions that they were currently feeling from a checklist. A pre-post difference was calculated by subtracting whether each adjective was marked before and after gameplay, allowing for tests of whether participants felt certain emotions more, less, or the same after each game. This produced three possible emotional change outcomes: those experiencing an emotional reduction were provided with a score of −1, those with no change received a score of 0, and those experiencing an emotional increase were provided with a score of 1. Because this was an experimental procedure, non-gamers also played the same games as the gamers, allowing for a comparison of responsiveness among three groups: pathological video-gamers, non-pathological video-gamers, and non-gamers. Because three total games were played, three emotional change scores were derived from each participant . Chi-square tests were performed comparing three gamer types on the three possible emotion outcomes for several emotions. The results are shown in We hypothesized that pathological gamers would feel less calm and peaceful after playing a video game, as they should be highly reactive to them. We also expected that non-gamers would feel less calm and peaceful after playing, as they would not be used to playing them. This was the pattern found. Pathological gamers and non-gamers were both significantly more likely than would be expected to feel less calm, less peaceful, and less pleasant post-play. A different pattern was expected for agitation and irritation, such that pathological gamers were expected to feel less agitated and irritated, but non-gamers might be expected to feel more. This pattern was also found. Pathological video-gamers were significantly less agitated and irritated, but non-gamers felt more post-game agitation and irritation . Research has shown that playing violent games increases hostile feelings in the short term e.g., ,44). Res. Res44])both happier and less happy post-play whereas there was no systematic relation for non-gamers or non-pathological gamers.We hypothesized that pathological gamers would report higher post-play levels of feeling happy and energetic. The pattern was not this clear. Pathological gamers reported higher levels of feeling energetic post-play, as did non-gamers. However, pathological gamers as a group were more likely to feel Some researchers have suggested that a feeling of power may be a primary motivation for playing . We predFinally, we predicted that pathological gamers would feel less lonely, sad, and unhappy after playing. This pattern was found. Pathological gamers were more likely to feel less lonely, sad , and unhappy after playing a video game. There was no systematic relation for non-gamers or non-pathological gamers. After playing, participants rated each game on several dimensions. We hypothesized that when the dimension referred to a somewhat objective quality of the game , that there would be no difference between gamer types, but when dimensions referred to a subjective personal appraisal of the game , that pathological gamers would rate the games higher than non- pathological gamers or non-gamers. Analyses of Variance were conducted on each of the ratings, with gamer group as the between-groups factor , far, far51])The prevalence of pathological video-gaming was lower in Study 2 than in Study 1 . There are several reasons for the lower prevalence among older adolescents than younger ones. First, we modified our items to be stricter on four dimensions. The items were written to mirror the DSM-IV pathological gambling criteria more closely (because these data were collected prior to DSM-5 being available), whereas for the younger adolescents the items were based on these criteria, but were worded to be understandable to 8th graders. Similarly, two additional items were written to match the DSM more closely, one item was dropped and the diagnostic cut-point was raised for college students. Second, the options provided to respondents were made stricter for college students in Study 2, where most items only had yes/no options, whereas most items had yes/no/sometimes options for younger adolescents and sometimes was grouped with “yes” for most items. Related to this point, we noted some cases of undergraduates marking “do not know” on several items rather than marking “yes”. Several of these cases looked like they were pathological when considering their overall pattern of video game use, but were classified as non-pathological due to our strict criteria. The only potential surprise was that pathological gamers did not differ on their ratings of how frustrating the games were to play. It could be argued from a cue reactivity approach that pathological gamers should find the games more frustrating, but it could also be the case that pathological gamers were likely to be more proficient and therefore would find the games less frustrating. The lack of any significant effect does not shed any light on these two competing hypotheses.Third, it may be that college students are less vulnerable to pathological video-gaming by virtue of their being a generally high-functioning group. Finally, it may be that developmental differences are implicated, such that younger adolescents are more vulnerable to pathological video-gaming, perhaps because they have fewer competing requirements for their time than college students. This study does not allow us to determine which, if any, of these accounts for the differences in prevalence rates. If there is some bias in our approach with older adolescents, it is possible that our percentages underestimate the prevalence in this age group. A national survey of American youth aged 8 to 18 put the prevalence at 8.5% of gamers . NeverthIn Study 3, each participant played three games and provided information on their emotional states and judged several dimensions of the games. Theoretically, pathological gamers should show evidence of heightened reactivity. As hypothesized, pathological gamers reported greater changes in emotional states and rated their experiences of playing the games as more positive than non-pathological gamers and non-gamers. how mad participants felt. We would recommend that future research measuring emotional responses to games rate how much they feel each, rather than the dichotomous checklist used by the MAACL. If nothing else, this would be more sensitive to change. Note that this is not identical to traditional cue reactivity, as playing a video game for 20 minutes is more than a “cue”. Nonetheless, the data supported the primary hypothesis that pathological gamers would be more emotionally reactive to playing video games. Pathological gamers’ pattern of emotional reactions to playing games was complex, however, and our interpretation should be viewed with caution until further research can replicate it. One interpretation is that pathological gamers reported less agitation and irritation after playing perhaps because it provided a “fix”. Pathological gamers reported feeling less lonely, sad, and unhappy and more energetic after playing. Given that one criterion for addiction is that the player is motivated to play to escape from negative emotional states, these data support the idea that pathological gamers associated games with decreased negative feelings. However, they also reported feeling less calm, peaceful, and pleasant. This appears very similar to traditional cue reactivity, where presentation with an addiction-related stimulus increased symptoms of withdrawal and craving e.g., ,53). In . In 53])When rating the gaming experience for each game, pathological gamers rated the games significantly more favorably than both non-gamers and non- pathological gamers. They considered the games to be more entertaining, exciting, fun, absorbing, arousing, enjoyable, involving, stimulating, and addicting than non-gamers and non- pathological gamers. They also rated the games as less boring than other participants. As predicted, they did not differ on ratings of more objective characteristics of the games, such as how violent, action-packed, or difficult the games were. It is for this reason that some researchers have included a “sometimes” category and have scored it as halfway between a “yes” and a “no” ,46.Several definitional issues remain to be studied. For example, we based our categorization on DSM-style criteria, where participants who answered yes to five or more of the diagnostic criteria were classified as pathological gamers and all others were classified as non-pathological. The studies reported here provide some evidence of validity for this dichotomous categorical approach using a cut-off point. However, the number of the diagnostic criteria a gamer presents to indicate levels of disorder could be equally useful. The fact that we found greater test-retest reliability for the number of criteria present than for whether the participants fell above or below our cut point suggests that additional studies should examine this issue, although we recognize the clinical value of introducing cut-off values for diagnostic purposes. Perhaps there are degrees of pathological use that would represent different challenges and would need to be treated differently. A related issue concerns how well checklist-style screening tools can differentiate highly engaged gamers from pathological gamers e.g., ,54). The. The54])Our hypotheses were based on the theoretical position that most types of addictions should show similar patterns of correlations, such as with higher hostility and antisocial behaviors. Although this was largely confirmed, it is worth considering why that might be. There is no necessary reason why pathological gaming should predict aggressive behaviors. Our speculation is that this pattern is likely indicative of an underlying impulse-control problem, which is how we currently consider Internet Gaming Disorder. Future studies should test this hypothesis.Studies 1 and 2 are limited by their correlational nature, and we make no claims about whether pathological use is the result of, the cause of, or simply co-occur with the several comorbid factors we measured or could have measured. Because the purpose of these studies was to document patterns of relationships with pathological video-gaming, we did not report any analyses attempting to control for any of the factors other than gender. These data are possibly limited also by their date of collection (early-to-mid 2000s). It is unclear, however, exactly how the date of collection may limit them. Although games have changed dramatically in the past decade, this study focuses on the gamers rather than the games. Internet gaming disorder is defined by experiencing dysfunction due to games, not by the type of games played. As games have gotten more interactive, more engaging, and more available, it is certainly possible that more gamers are having problems, but it is unclear why this would change the pattern of behaviors that are correlated with IGD. Nonetheless, this is an empirical question deserving of additional study.et al.’s (2014) [The purpose of this study was to provide tests of the construct of pathological video gaming, not to validate an instrument. Nonetheless, the instrument used in Studies 2 and 3 shares many characteristics with the types of instruments being considered in response to the definition of Internet Gaming Disorder. For example, using Petry s (2014)  discussiAlthough the literature dedicated to the topic of Internet Gaming Disorder is growing, it is still unclear at this point whether these are distinct problems of their own, or whether they are part of some broader pattern of pathologies. A large body of studies including outcomes of pathological use while controlling for various factors, such as comorbid pathologies, remain to be conducted. These will need to be conducted within theoretical frameworks of pathways to addiction. More research is needed regarding the etiology and course of pathological video-gaming. Future studies should continue to examine the developmental course of pathological video-gaming , establ


When liquid crystals are confined to finite volumes, the competition between the surface anchoring imposed by the boundaries and the intrinsic orientational symmetry-breaking of these materials gives rise to a host of intriguing phenomena involving topological defect structures. For synthetic molecular mesogens, like the ones used in liquid-crystal displays, these defect structures are independent of the size of the molecules and well described by continuum theories. In contrast, colloidal systems such as carbon nanotubes and biopolymers have micron-sized lengths, so continuum descriptions are expected to break down under strong confinement conditions. Here, we show, by a combination of computer simulations and experiments with virus particles in tailor-made disk- and annulus-shaped microchambers, that strong confinement of colloidal liquid crystals leads to novel defect-stabilized symmetrical domain structures. These finite-size effects point to a potential for designing optically active microstructures, exploiting the as yet unexplored regime of highly confined liquid crystals. Liquid crystals confined to micrometre-sized geometries can be well described by a continuum theory, where the size effect of constituent mesogens is negligible. Here, the authors show how the continuum theory breaks down in colloidal liquid crystal, leading to the formation of defect-mediated domains. The study of liquid crystals in confinement has a history stretching back to the days of the development of the first twisted nematic display cellsFirst and foremost, this concerned the study of topological defects, which in these systems arise both spontaneously or can be induced and modulated through the geometry of confinement and the imposed boundary conditions. Starting in the 1970s a major effort was undertaken to understand and classify these defect structures23458910111518In order to reach this regime, we take a cue from nature, which provides a host of viral particles and filamentous biopolymers whose lengths are upward of the micrometer scale. Moreover, biopolymers in nature are actually often strongly confined. Cytoskeletal filaments for instance are packed at high density within thin sheet-like lamellipodia and finger-like filopodiafd-virus particles.To address this question in a well-controlled setting, we will consider model systems composed of rod-like particles, using both simulations and experiments with n-fold symmetric domain structures appear, controlled by the size of the inner hole.Since the interactions between colloidal particles, especially in physiological salt conditions, are dominated by short-range repulsions, the interactions between the particles in the simulations are taken to be of the hard body type. Since the seminal work of Onsager272930χ=1 , at its boundary (Bb) or are present as virtual singularities located either a finite distance from the centre (Bo), but still causing a noticeable distortion of the alignment pattern on the inside or effectively infinitely far away (B∞), yielding a nearly homogeneous nematic state. The virtually bipolar patterns (Bo and B∞) have been predicted to occur under weak anchoring conditions in elongated droplet shapes35Bi pattern observed for shorter rods and at relatively low density in which a finite boundary layer of wall-aligned particles encloses the two singularities, however, was hitherto not described, and provides a clear signal that local packing effects can cause deviations from the continuum picture. An overview of the patterns found in the circular geometry can be found in 3738Depending on the aspect ratio and the packing fraction of the particles, we find that the singularities are located inside the disc  diffusion in the nematic background by fluorescence microscopyRouter ranges from 5 to 50 μm, yielding confinement in the range κ=10−1–10−2, and whose inner hole radius Rinner ranges from 0 to 0.7 times the outer radius Router. The chambers have a height in the range of H=1–3 μm, which is the minimal thickness that was experimentally attainable. We acquired confocal fluorescence time-lapse image series of chambers containing fd-rods with a small fraction of fluorescently labelled rods serving as tracers. To compute director fields, we extract the time-averaged orientation of the nematic director for each image pixel by the automated image analysis  showing two opposite +1/2 singularities (D3) showing three +1/2 singularities (D∞) that lacks singularities  is a salient parameter. However, our results show that simulations, albeit on systems that are as yet significantly smaller than the experimentally realized ones , as well as more realistic quasi-2D situations, H=3D and 6D. We want to study the regime in which the interparticle alignment competes with the boundary alignment. Since the boundary anchoring length for spherocylindrical rods is of the order of the particle length,27Router to be comparable to L. A convenient measure for the degree of lateral confinement is the ratio κ=L/(2Router), which is unity when the rods can just fit in the volume and zero for the unconfined case. In order to obtain a reasonable compromise between computational tractability and realism we used an outer radius Router=40D and particle aspect ratios in the range L/D=15–25, yielding κ=0.2–0.3. The number of particles was chosen to obtain packing fractions at which the corresponding unconfined system is in a nematic stateH=6D. To systematically characterize any patterns observed, we measured a spatially resolved version of the standard second-rank tensorial order parameter. Local order parameter tensors have already been employed previously in the study of inhomogeneous liquid crystals, both in lattice models51The excluded volume interactions of the rods with the walls favour planar degenerate boundary conditionsfd-virus rods were grown using a standard protocolfd-buffer solution . Assay suspensions were prepared at concentrations of 24 mg ml−1, slightly above the bulk isotropic–nematic biphasic region, which occurs at ∼20 mg ml−1, in agreement with the Onsager theoryfd-buffer containing 0.1 wt% of the amphiphilic block copolymer Pluronic F-127 (Sigma-Aldrich). This treatment effectively blocked nonspecific adsorption of fd-rods, as confirmed by time-lapse imaging of rod diffusion. Saturation of the PDMS with buffer prevented drying of the sample for at least 24 h.Microchambers were assembled using a standard photolithographic technique described elsewherefd-virus suspensions was placed on a glass-photoresist substrate and pressed against rubber-coated glass to form microchambers. We hermetically sealed the glass edges with VALAP and let samples equilibrate for at least 30 min before visualizing by fluorescence microscopy. We only consider well-sealed chambers for quantification. Approximately 40% of all chambers are well-sealed. Chambers that were not well-sealed were evident by fluorescently labelled rods escaping from the chamber. The rods rapidly organized in steady-state nematic patterns within 30 min after filling the chambers. When we filled the chambers with the isotropic phase below the biphasic region, a nematic was not formed and the samples remained isotropic. This observation implies that the filling (and confinement) were not sufficient to induce a nematic.A drop of 2  s−1 along the nematic director and 0.1 μm2 s−1 perpendicular to the nematic directorθ> given time-averaged orientations θ of labelled fd-rods across all images acquired  a spinning disk confocal scanner  on an inverted microscope  with a cooled, electron-multiplying charged-coupled device  and (2) a Nikon C1 confocal point scanner on an inverted microscope  with a photomultiplier tube detector . Labelled rods were excited with 488 nm laser light (Coherent). A series of images were recorded over a long enough time interval such that viruses diffused across the entire chamber. The average diffusion constant of virus rods in the nematic phase is 1 μmacquired .Router and Rinner/Router. We define the probability that a pattern P occurs in a given chamber geometry G as the number of observed instances of P divided by the total number of well-sealed chambers with geometry G. A total of 243 chambers were analyzed: 80, 27, 26, 36, 43 and 31 chambers for Rinner/Router=0, 0.1, 0.2, 0.3, 0.5 and 0.7, respectively; 77, 75, 55, 25, 9 and 2 chambers for Router/μm=5, 10, 15, 25, 35 and 50, respectively; 113, 5, 23, 21, 33, 32 and 16 chambers for patterns D2, D3, D∞, N, A1, A2, and A+, respectively.Rods formed a variety of liquid-crystal patterns. The pattern type was determined by visual inspection of the nematic director fields of all well-filled chambers on the chip. The data that support the findings of this study, as well as the computer codes used in the simulations, are available from the corresponding author upon request.How to cite this article: Gârlea, L. C. et al. Finite particle size drives defect-mediated domain structures in strongly confined colloidal liquid crystals. Nat. Commun. 7:12112 doi: 10.1038/ncomms12112 (2016).Supplementary Figures 1-12, Supplementary Tables 1-2, Supplementary Notes 1-8 and Supplementary References


Wireless sensor networks have been considered as an enabling technology for constructing smart cities. One important feature of wireless sensor networks is that the sensor nodes collaborate in some manner for communications. In this manuscript, we focus on the model of multiway relaying with full data exchange where each user wants to transmit and receive data to and from all other users in the network. We derive the capacity region for this specific model and propose a coding strategy through coset encoding. To obtain good performance with practical codes, we choose spatially-coupled LDPC (SC-LDPC) codes for the coded cooperation. In particular, for the message broadcasting from the relay, we construct multi-edge-type (MET) SC-LDPC codes by repeatedly applying coset encoding. Due to the capacity-achieving property of the SC-LDPC codes, we prove that the capacity region can theoretically be achieved by the proposed MET SC-LDPC codes. Numerical results with finite node degrees are provided, which show that the achievable rates approach the boundary of the capacity region in both binary erasure channels and additive white Gaussian channels. The rapid development of portable and wearable devices has further fueled the application of sensor networks, which helps to improve the city's sustainable growth and citizens' living quality.One important feature of WSNs is that the sensor nodes collaborate in some manner for information transmissions. Much of research on the physical-layer techniques has focused on relaying, which is an efficient cooperative strategy to improve throughput and coverage of the sensor network. The three-node relay channel , consista priori information is available for decoding the codeword from the relay. Eventually, all of the members in the team are supposed to obtain the messages from all of the others. Since the information delivery in the first phase is essentially a peer-to-peer communication, in this manuscript, we focus on the second phase in which the relay broadcasts the messages to all of the members.In this manuscript, we are interested in a typical scenario which is called the multiway relay channel with full data exchange in  or the cetc.The capacity region for the general multi-user broadcast channel is not known yet. In ,6, the aa posteriori probability (MAP) threshold of the underlying LDPC block code. This code, in turn, approaches capacity as the node degrees increase. In addition to the capacity-achieving performance for various channels, the regularity of the SC-LDPC code allows us to avoid complicated re-optimization of the degree distributions for varying channel conditions. Meanwhile, this code enables recursive encoding and sliding-window decoding  is a codeword of the LDPC code defined by H if and only if the following constraint is satisfied:A parity-check matrix  to represent a code and use X to denote one codeword of .In the following, we use Tanner introduced an effective graphical representation for LDPC codes . In a bivd, cd) regular LDPC code is determined by the condition that every codeword bit participates in exactly vd parity-check equations and that every parity-check equation involves exactly cd codeword bits. The parameter vd is called the variable node degree, and cd is the check node degree.As originally defined by Gallager, a  regular LDPC code is:Since each parity-check equation typically reduces the number of degrees of freedom by one, it follows that the design rate of the  that satisfies:A nested code  is a pai2 is also a codeword of 1.That is, each codeword of H1 and H2 be parity-check matrices of dimension k1×n and of dimension k2 × n, respectively, k2 > k1. By bringing in an additional parity-check matrix HΔ of dimension (k2 – k1) × n, the nested codes can be realized by:The nested parity-check codes can be constructed as follows . Let H1 1 into 2k2−k1 cosets of 2.We can then partition 4.3.Multi-edge-type LDPC codes  can be cV, i.e., the codeword, is denoted by X. There are K types of check nodes in the graph, C0, C1, …, Cl …, Ck−1. The parity-check matrices, which correspond to the K types of edges connecting the variable nodes and the different types of check nodes, are denoted by H0, H1, …, Hl, …, Hk-1, and have variable and check node degrees , , …, , …, , respectively. The MET nested LDPC code can be described by the stacked parity-check matrix H, and we have:An MET nested LDPC code can be illustrated by the Tanner graph in Definition 2.  A multi-edge-type nested LDPC ensemble includes all of the bipartite graphs where each variable node is connected to d ∈ .4.4.m0, m1, and m2 are of lengths k0, k1 and k2 bits. To combine the three messages in a single transmission, the relay uses a double binning strategy: a high-rate code of length n is split into 2nR1 × 2nR2 disjoint sub-codes i,j, with i ∈ {1,…,2 nR1} and j ∈ {1,…, 2nR2}, each of rate R0. Note that k0 = nR0, k1 = nR1 and k2 = nR2. For encoding, the relay lets the k1 and k2 message bits m1 and m2 determine which sub-code is selected, and he uses the chosen sub-code m1,m2 for encoding m0. This encoding strategy can be realized by using a coset code m1,m2 of the MET nested LDPC code that is selected by the messages m1 and m2 as follows:H0 is a (k′ × n) matrix, k′ satisfies n = k0 + k′ + k1 + k2, H1 is a (k1 × n) matrix and H2 is a (k2 × n) matrix.Based on the nested LDPC codes, in the following, we illustrate the coding strategy for the multiway relay channel with full data exchange. Since the first phase is in fact a peer-to-peer transmission, we focus particularly on the transmission strategy in the broadcast phase. We start with the case of two users and one relay. We assume that the binary messages H0, H1, and H2 are given, the encoding can be carried out by mapping the message m0 into a codeword which simultaneously satisfies the check constraints Once the Tanner graph of an MET nested LDPC code is given or, equivalently, the parity-check matrices Cd0 = Cd1 = Cd2 ≡ cd, the rate for encoding m0 is:m1 and m2 are, respectively:If U1 has perfect knowledge of m1, he interprets X as a codeword of a two-edge-type nested LDPC code and uses:X. With the decoded codeword X̂, U1 obtains m0 and recovers m2 by using the fact that m2 = H2XT following from U2 recovers the messages m0 and m1 by using m2 as side information.The decoding at each user is carried out as follows. Since X that satisfies:lCd = cd for all l ∈ {0,1, 2,…, K – 1}, we get the rate for encoding m0 as:ml is:l ∈ {1,2,…,K−1}.The above coding strategy can be easily extended to the multi-user case. A multiple binning technique is utilized to combine all of the messages in a single transmission. For the general case, the encoding can be realized by selecting a codeword lU form a vector vl of length lP. Then, the decoding of the codeword X (the message m0) at lU is carried out by satisfying:When decoding, each user utilizes the side information available at the receiver. We assume that the indexes of the available messages at lU can be recovered by using the decoded X and sub-parity-check equations in As for the two-user case, the other messages designated to X that satisfies that:We again have a look at the example in U1, satisfying:U2 and satisfying:U3.The decoding is carried out by satisfying:In the above, we have illustrated the coding strategy using LDPC codes. In general, the regular LDPC codes suffer from poor performance. The performance can be improved by introducing irregularity to the node degrees. However, an irregular degree distribution needs to be derived to match a given channel condition, which complicates the code design. Therefore, we are interested in searching for code constructions with a good performance and a low optimization overhead. The spatially-coupled LDPC codes are then good candidates for this purpose.5.N-edge-type nested SC-LDPC code embedded in the MET structure is capacity achieving.In this section, we first give a brief introduction of spatially-coupled LDPC codes. Then, we introduce the construction of multi-edge-type nested SC-LDPC codes. The property of the proposed codes is analyzed. We will show that any 5.1.vd,cd} binary spatially-coupled LDPC code can be defined by an infinite parity-check matrix: , and the code needs to be initialized in the beginning and terminated in the end. All of the submatrices hi(t) are sparse, and accordingly, the overall parity-check matrix is sparse.A regular { matrix: H∞= of cardinality N, N ∈ , the MET nested SC-LDPC code ensembleΦ = {dΦv, dΦc, M, L, w} vl type-l check nodes, and each type-l check node has dcl edges connecting to the variable nodes, for all lof codeword length M L includes all of the bipartite graphs where each variable node is connected to d ∈ Φ. vl type-l edges of a variable node at position t uniformly and independently connects to the type-l check nodes in the rangeMore specifically, each of the d .5.3.In this section, we discuss the performance of the MET nested SC-LDPC codes.We have shown in  that, whN-edge-type case. We can show that an arbitrarily-chosen N-edge-type  nested SC-LDPC code ensemble Φ = {vdΦ, cdΦ, M, L, w} embedded in the MET code with node degrees { : l ∈ Φ} has the same design rate and the same BP threshold as a standard SC-LDPC code {Σl∈Φlvd,cd, M, L, w} if lcd = cd for all l ∈ Φ. The proof can be done recursively as follows. We choose arbitrarily a two-edge-type nested SC-LDPC code {m,n} = {vd{m,n}c,d{m,n}, M, L,w} from the MET code, where m ∈ Φ, n ∈ Φ and m ≠ n. This code is equivalent to a standard SC-LDPC code {mvd + nvd, cd, M, L, w} when mcd = ncd = mcdthreshold as a standard SC-LDPC code The edges of type-m and type-n can then be considered as the same type of edge. Now, we chose arbitrarily a type l, l ∈ Φ, l ≠ m and l ≠ n and add all type-l edges to the existing structure. If lcd = cd, we obtain a code that has the same design rate and BP threshold as a standard SC-LDPC code {mv +dnv +dlvd, cd, M, L, w} and is therefore capacity achieving. We repeat the above procedure until all of the N types of edges are added to the graph. The order in which we added the new edge type to the graph does not affect the result.In the following, we extend the discussion to the lcd = cd∀l ∈ , all of the arbitrarily-chosen N-edge-type  nested SC-LDPC code ensembles embedded in the MET code are simultaneously capacity achieving in the limit of large parameters.Based on the above derivation, we obtain the conclusion: if 6.In this section, we apply the MET nested SC-LDPC codes for the multiway relay channel with full data exchange. We will prove that the capacity region of the model can be achieved by using the proposed code structure.vd0, cd0, M, L, w}, {vd1, cd1, M, L, w} and {vd2, cd2, M, L, w}. We denote the MET nested SC-LDPC code ensemble by  = {vd{0,1,2}c,d{0,1,2}, M, L, w}. The embedded two-edge-type SC-LDPC code, which is to be decoded at U1, is denoted by {0,1} = {vd{0,1} ,cd{0,1}, M, L, w}. Similarly, the two-edge-type code to be decoded at 2U is denoted by {0,2} = {vd{0,2}, cd{0,2}, M, L, w}. If we write the MET SC-LDPC codes in the form of parity-check matrix, the only difference to Again, we start with the case of two users and one relay. When applying the spatially-coupled LDPC codes, the connections between the variable nodes and the three types of check nodes are characterized by {{0,1} and {0,2} are simultaneously capacity achieving. Based on these facts, we give the following theorem.We apply the theoretical results in Section 5.3 for the performance analysis. Following Section 5.3, the two-edge-type codes Theorem 4.The capacity region of the two-way broadcast channel with a common message can be achieved by using an MET nested SC-LDPC code = {vd{0,1,2}, cd{o,1,2}, M, L, w}.Proof. We assume that the capacities of the two individual links are C1 and C2, which together form the bound of the capacity region. The rate for broadcasting m0 is assumed to be R0, and R0 ≤ min. For constructing an MET nested SC-LDPC code, we first choose a check degree cd which is the same for all types of check nodes. With this cd, we decide the variable degrees by satisfying: = {vd{0,1,2}, cd{0,1,2}, M, L, w} as explained in Section 5.2.After determining the parameters, we construct an MET nested SC-LDPC code CN0, CN1 and CN2, respectively. The number of variable nodes is vN. According to the definition of encoding rate in R0 = 1 − (CN0 + CN1 + CN1)/vN, R1 = CN1/VN, and R2 = CN2/VN. The design rate of the code {0,1} for U1 is given as:Assume that the numbers of three types of check nodes are {o,1} is capacity achieving, i.e., in the limit of large M, L and w,Since the code U2 link, we can prove that:In a similar manner, for the relay- Therefore, the capacity region can be achieved by using the MET nested SC-LDPC code.l-th type of check nodes is realized by the individual code {lvd, lcd, M, L, w}, l ∈ . In the following, we briefly discuss the performance of the proposed code construction in the multiway relay channel.Now, we generalize to the multiway relay case. When constructing the MET nested SC-LDPC code, the connection between the variable nodes and the Theorem 5.The capacity region of the multi-user broadcast channel with full data exchange can be achieved by using multi-edge-type SC-LDPC codes.Proof. For the given channel capacities {Cl : l ∈ } and the rate R0, we choose the node degrees by satisfying:l ∈ . For a predetermined check degree cd, there must exist a unique nonnegative solution set {vd0, lvd, …, lvd,…, vdK−1} satisfying the K independent equations on condition that R0 ≤ minand lC ≥ kC if l ⊆ k for l, k, ∈ {1, 2, …, K − 1}.lU is asymptotically:l ∈ . Then, the boundary of the capacity region in Theorem 1 is achieved.We have shown in Section 5.3 that all of the N-edge-type nested SC-LDPC codes are simultaneously capacity achieving in the limit of large parameters. Therefore, the rate to be decoded at 7.In this section, we present the numerical results in terms of BP decoding thresholds and bit erasure rates (BERs) for the proposed MET nested SC-LDPC codes. The results are based on the density evolution for finite node degrees and based on simulations with finite code lengths. Without loss of generality, we only include the results for the two-way relay channel. The results for the multiway relay channel present the same characteristics, and therefore, they are omitted here.{0,1} and {0,2} are capacity achieving, we consider only {0,1} for the performance evaluation. We set the parameters as Vd0 = 3, cd = 10, w = 3 and L = 100. Different variable degrees Vd1 ∈ {1,2, 3, 4, 5, 6} are used to realize different sum rates R0 + R2, where the tradeoff between R0 and R2 is controlled by Vd2, which is upper bounded by Vd2c≤ d − (Vd0 + vd1)  are listed in the legend, and we set M = 1000 and L = 100. It can be seen that the MET SC-LDPC codes generally provide good performance over BECs. Similar observations can be obtained in BI-AWGN channels, and the results are omitted here. We also want to point out that the complexity and latency due to the encoding and decoding of SC-LDPC codes are not an issue for their applications in practice, since SC-LDPC codes allow recursive encoding and sliding-window decoding.In the following, we provide the simulation results for the SC-LDPC codes with finite code lengths over BECs. The bit erasure rates are plotted in 8.N-edge-type SC-LDPC code embedded in the multi-edge-type construction is capacity achieving. By applying the above code construction to the broadcast phase of the multiway relay channel, each user recovers the message from the relay and all of the other users based on the receiver side information. We have proven that the capacity region of the specific model can be achieved by using the proposed construction. Numerical results were provided in both binary erasure channels and AWGN channels, which verified the theoretical analysis.In this manuscript, we proposed multi-edge-type spatially-coupled LDPC codes through coset encoding for the multiway relay channel with full data exchange. This model has various applications in wireless sensor networks, and we have provided a practical coding solution for the communication aspects of the model. We have proven that an arbitrarily-chosen


Although the depth of the counting chamber is an important factor influencing sperm counting, no research has yet been reported on the measurement and comparison of the depth of the chamber. We measured the exact depths of six kinds of spermcounting chambers and evaluated their accuracy.In this prospective study, the depths of six kinds of spermcounting chambers for both manual and computer-aided semen analyses, including Makler (n=24), Macro (n=32), Geoffrey (n=34), GoldCyto (n=20), Leja (n=20) and Cell-VU(n=20), were measured with the Filmetrics F20 Spectral Reflectance Thin-Film Measurement System, then the mean depth, the range and the coefficient of variation (CV) ofeach chamber, and the mean depth, relative deviation and acceptability of each kind ofchamber were calculated by the closeness to the nominal value. Among the 24 Maklerchambers, 5 were new and 19 were used, and the other five kinds were all new chambers.The depths  of Makler (new), Macro and Geoffrey chamberswere 11.07 ± 0.41, 10.19 ± 0.48 and 10.00 ± 0.28, respectively, while those of GoldCyto,Leja and Cell-VU chambers were 23.76 ± 2.15, 20.49 ± 0.22 and 24.22 ± 2.58, respectively. The acceptability of Geoffrey chambers was the highest (94.12%), followed byMacro (65.63%), Leja (35%) and Makler (20%), while that of the other two kinds andthe used Makler chamber was zero.There existed some difference between the actual depth and the correspondingnominal value for sperm counting chambers, and the overall acceptability was very low. Moreover, the abrasion caused by the long use, as of Makler chamber, for example, may result in unacceptability of the chamber. In order to ensure the accuracy and repeatability of sperm concentration results, the depth of the sperm counting chamber must be checked regularly. Semen analysis counts significantly among laboratory examinations in andrology, and sperm concentration is one of the basic parameters of routine semen analysis. Although the world health organization (WHO) laboratory manual for the examination and processing of human semen recommends the Neubauer haemocytometer chamber as a sperm counting chamber, and provides methods for quality control of sperm counting , many otMany factors contribute to the differences in the results of sperm counting, such as sample mixing, loading, environmental temperature, etc. ,16. Howe2 on Si Standard Thickness=(725.9 ± 1.1) Å, wascertified by the NIST, USA. Five 10 μm-deep Maklersperm chambers were purchased from Sefi MedicalInstruments, Israel. Thirty-two Macro sperm countingchambers and 34 Geoffrey chambers, both of 10 μmdepth, were provided by Jiangsu Rich Life ScienceInstrument Co., Ltd . Twenty Gold-Cyto chambers  and 20 Leja chambers , both 20 μm in depth, were bought fromGuangdong Youning Trade Co., Ltd . Twenty Cell-VU chambers of 20 μm in depth were purchasedfrom Nanjing Yu’an Instrument Co., Ltd . In addition, nineteen 10 μm-deep Maklersperm counting chambers , which had been used for several months oryears, were obtained from different andrology laboratoriesin China. Makler, Macro and Geoffrey chambersare manufactured with the base glass and separatecover glass and can be used repeatedly. GoldCytoand Leja chambers belong to the disposable kind withfixed depth. Cell-VU chamber, also made from thebase glass and separate cover glass, can be used repeatedlyor as a disposable chamber.The Filmetrics F20 Spectral Reflectance Thin-FilmMeasurement System was provided by the DYMEKCompany, USA, which has a measurable range from15 nm to 70 μm and the lowest detectable limit of 1nm. The system can be used to measure the thicknessof the thin-film by analyzing the reflected light off itstwo surfaces and then calculate the spectral reflectanceat a range of wavelength. A reflectance calculatorgives the thickness value of the thin-film based onthe complex-matrix form of the Fresnel equations. Afilm of standard thickness -12016),SiOThis was a prospective study. First, the Filmetrics F20 Spectral Reflectance Thin-Film Measurement System was calibrated with the standard film according to the operating instruction. Then, six kinds of sperm counting chamber, including Makler, Cell-VU, Leja, Macro, GoldCyto and Geoffrey, were numbered randomly, cleansed with a solution , and confirmed to be devoid of impurity under a microscope. Finally, the depths of the upper, lower, left, right and central parts of each chamber were measured, and the average depth, SD and the range of depth  of each chamber was calculated automatically, all with the Filmetrics F20 System according to the operating instructions. All the sperm counting chambers were measured by one technician, and the supervision and verification of the results were conducted by another. All the data obtained were put into an Excel table for calculation of the mean depth, the range of depth, and coefficient of variation (CV) of each chamber. For those with double chambers, the paired t test was used to compare the difference between the two; for those with more than two chambers, the comparison was made by the LSD-t test, and the new and used Makler chambers were compared by the independent-sample t test. The SPSS  version 11.0 software was used for analyses, and statistically significant difference was designed to be P<0.05. For a 5% permitted error, the chambers with a measured depth of 10 ± 0.5 μm or 20 ± 1 μm were judged as compatible with a nominal value of 10 μm or 20 μm, respectively, followed by assessment of the acceptability of different sperm counting chambers. The depths of all the six kinds of sperm counting chambers were measured. The results are shown in table 1. The average depth of the 32 Macro sperm counting chambers  was 10.19 μm, and CV was 4.71%. The range of the mean and CV of the five depth measurements of Macro chambers were 0.14 μm and 0.58%, respectively, and 65.63% of the 32 chambers were within acceptable limits. The Makler sperm counting chamber is also a single chamber unit with depth of 10 μm. The mean depth of the five new Makler chambers was 11.07 μm, with a relative deviation of 10.7%, exceeding the allowable range of 5%, and that of the 19 used Makler chambers was 12.72 μm, with a relative deviation of 27.2%, far exceeding the allowable range. Moreover, the CV (8.49%) for all used chambers and the mean range (0.43 μm) and CV (1.33%) of the depth between the 5 points were obviously higher than those of the Macro chambers. The acceptability was 20% for the new Makler chambers, and zero for the used ones. A Cell-VU sperm counting chamber includes two 20 μm-deep chambers. The mean depth and relative deviation of the 20 left chambers were 23.94 μm and 19.7%, and those of the 20 right ones were 24.49 μm and 22.45%, respectively. Although there was no significant difference in depth between the left and right chambers , the CVs (12.36 vs. 10.41%) for all the chambers on either side and themean ranges (1.64 μm vs. 2.21 μm) and CVs (2.66vs. 3.47%) of the depth between the 5 points in eachchamber were very high. The acceptability was 5%(1/20) for both the left and right chambers. If it wasrequired that the errors of the two chambers in one setto be within the allowable range, the acceptability ofthe Cell-VU chamber was zero.A Geoffrey sperm counting chamber contains two 10 μm-deep chambers. The mean depth of the 34 left chambers was 10.01 μm and that of the 34 right ones was 9.99 μm, with no significant difference between them . The CVs (2.90 vs. 2.80%) for all the chambers on either side, and the mean ranges (0.11 vs. 0.11 μm) and CVs (0.45 vs. 0.47%) of the depth between the 5 points in each chamber were all very low. The acceptability values of the left and right chambers were 100 and 94.12%, respectively. If it was required that the errors of the two chambers in one set to be within the allowable range, the acceptability of the Geoffrey chamber was 94.12%. A GoldCyto sperm counting chamber contains four 20 μm-deep chambers (A-D). The mean depths of chambers A, B, C and D of the 20 GlodCyto sets were 22.19, 24.79, 24.96 and 23.11 μm, respectively. The corresponding relative deviations were 10.95, 23.95, 24.8 and 15.55%, respectively, with a total deviation of 18.8%, all far exceeding the allowable range of 5%. However, the depths of chambers B and C were significantly greater than those of A and D (P<0.05), although there was no significant differences in depth either between B and C or between A and D. The acceptability values of chambers A, B, C, and D were 30, 5, 5 and 10%, respectively. If one of the chambers was unacceptable, the whole unit was appraised as unacceptable and the acceptability of the GoldCyto sperm counting chamber was zero. A Leja sperm counting chamber consists of eight 20 μm-deep chambers (A-H). The mean depths of chambers A, B, C, D, E, F, G, and H of the 20 Leja chambers were 20.99, 20.37, 20.30, 20.34, 20.88, 20.31, 20.17 and 20.55 μm, respectively. The corresponding relative deviations were 4.95, 1.85, 1.5, 1.7, 4.4, 1.55, 0.85 and 2.75%, respectively, indicating that all were within the allowable range of 5%. However, the depths of chambers A and E were significantly greater than those of B, C, D, F, G, and H (P<0.05), and the depth of H was greater than that of G (P<0.05). The acceptability values of chambers A, B, C, D, E, F, G, and H were 65, 95, 95, 100, 65, 100, 95 and 95%, respectively. However, if one of the chambers was unacceptable, the whole unit was appraised as unacceptable and the acceptability of the Leja sperm counting chamber was 35%. thedition) emphasizes regular measurement of the depth of the sperm counting chamber, but in practice, it is never measured since its purchase till worn out. Moreover, there is a lack of methods to identify the chambers and specific measures for the implementation of quality control for the chambers. The WHO Manual  range for most of the chambers, which inevitably results in a large variation in sperm concentration in clinical application. Therefore, in order to ensure the accuracy and repeatability of semen analysis results, the depth of the sperm counting chamber must be checked regularly, even though strictly measured at delivery inspection, and unqualified chambers must be rejected. In addition, the measurement report for each sperm counting chamber must be attached to the product for an andrology laboratory.