Distance Properties of Short LDPC Codes and their Impact on the BP, ML and Near-ML Decoding Performance

Parameters of LDPC codes, such as minimum distance, stopping distance, stopping redundancy, girth of the Tanner graph, and their influence on the frame error rate performance of the BP, ML and near-ML decoding over a BEC and an AWGN channel are studied. Both random and structured LDPC codes are considered. In particular, the BP decoding is applied to the code parity-check matrices with an increasing number of redundant rows, and the convergence of the performance to that of the ML decoding is analyzed. A comparison of the simulated BP, ML, and near-ML performance with the improved theoretical bounds on the error probability based on the exact weight spectrum coefficients and the exact stopping size spectrum coefficients is presented. It is observed that decoding performance very close to the ML decoding performance can be achieved with a relatively small number of redundant rows for some codes, for both the BEC and the AWGN channels

Country differences in the diagnosis and management of coronary heart disease : a comparison between the US, the UK and Germany

Background The way patients with coronary heart disease (CHD) are treated is partly determined by non-medical factors. There is a solid body of evidence that patient and physician characteristics influence doctors' management decisions. Relatively little is known about the role of structural issues in the decision making process. This study focuses on the question whether doctors' diagnostic and therapeutic decisions are influenced by the health care system in which they take place. This non-medical determinant of medical decision-making was investigated in an international research project in the US, the UK and Germany. Methods Videotaped patients within an experimental study design were used. Experienced actors played the role of patients with symptoms of CHD. Several alternative versions were taped featuring the same script with patients of different sex, age and social status. The videotapes were shown to 384 randomly selected primary care physicians in the three countries under study. The sample was stratified on gender and duration of professional experience. Physicians were asked how they would diagnose and manage the patient after watching the video vignette using a questionnaire with standardised and open-ended questions. Results Results show only small differences in decision making between British and American physicians in essential aspects of care. About 90% of the UK and US doctors identified CHD as one of the possible diagnoses. Further similarities were found in test ordering and lifestyle advice. Some differences between the US and UK were found in the certainty of the diagnoses, prescribed medications and referral behaviour. There are numerous significant differences between Germany and the other two countries. German physicians would ask fewer questions, they would order fewer tests, prescribe fewer medications and give less lifestyle advice. Conclusion Although all physicians in the three countries under study were presented exactly the same patient, some disparities in the diagnostic and patient management decisions were evident. Since other possible influences on doctors treatment decisions are controlled within the experimental design, characteristics of the health care system seem to be a crucial factor within the decision making process

Amygdaloid Kindling and the GABA System

The effect of increased brain GABA levels on fully kindled amygdala seizures was investigated in Long-Evans rats. The newly synthesized GABA-transaminase inhibitor, -Γ-acetylenic GABA (GAG) administered on four consecutive days (100 mg/kg, followed by 50 mg/kg, i.p.) was found to either significantly reduce, or eliminate entirely, the behavioral seizures normally produced by amygdala stimulation. The effect is seen after the first injection of GAG although its magnitude was greater on subsequent days. Behavioral seizures reappeared 2 to 3 days after termination of GAG treatment. The duration of electrographic seizures (self-sustained amygdala after-discharge) was either unchanged or greater on the first day of GAG treatment, but was briefer on subsequent days. The duration of afterdischarges returned to normal levels 1 to 2 days earlier than the behavioral seizures after the termination of GAG. Picrotoxin (1.5-2 mg/kg, i.p.) did not antagonize either electrographic or behavioral effects of inhibition produced with GAG. Electrical stimulation of amygdala delivered during the initial sedation stage induced by picrotoxin resulted in further regression of kindled seizures in the majority of animals. Although in doses employed, GAG alleviates amygdaloid-kindled seizures its use requires caution in view of its ability to reduce arousal level. RÉSUMÉ L'effet de l'ÉlÉvation des taux cÉrÉbraux de GABA sur les crises amygdaliennes par effet d'embrasement complet a ÉtÉÉtudiÉ chez des rats Long-Evans. l'injection pendant 4 jours consÉcutifs de 100 mg/kg suivis de 50 mg/kg i.p. d'un inhibiteur de la GABA. Transaminase nouvellement synthÉtisÉ (Γ-acetylenic GABA ou GAG) a significativement rÉduit ou mÊme supprimÉ les crises normalement provoquÉes par la stimulation amygdalienne. l'effet est observÉ aprÈs la premiere injection de GAG, mais son importance s'accroit les jours suivants. Les crises rÉapparaissent 2 ou 3 jours aprÈs la fin du traitement au GAG. Du point de vue Électrographique, la durÉe de la postdÉcharge amygdalienne autoentretenue est inchingÉe ou accrue le premier jour du traitement, mais elle diminue les jours suivants pour retourner À la normale un ou deux jours avant que les crises ne rÉapparaissent aprÈs la fin de ('administration du GAG. l'injection de picrotoxine (1.5-2 mg/kg i.p.) ne s'oppose pas aux effets inhibiteurs du GAG sur les crises ou leur accompagnement EEG. La stimulation Électrique de l'amygdala pendant l'Étape sÉdative initiate induite par la picrotoxine provoque une rÉgression supplÉmentaire des crises d'embrasement chez la majoritÉ des animaux. Bien que, aux doses utilisÉes, le GAG attÉnue les crises amyg-daliennes d'embrasement, son utilisation nÉcessite des prÉcautions compte tenu de sa tendance À rÉduire le niveau d'Éveil. RESUMEN En ratas Long-Evans se ha investigado el efecto del aumento de los niveles cerebrales de GABA, sobre los ataques originados en la amÍgdala totalmente condicionada, (Kindling). El recientemente sintetizado in-hibidor de la GABA transaminasa, Γ-acetilÉnico GABA (GAG), redujo significativamente o eliminÓ totalmente las crisis de comportamiento que habitualmente se producen con la estimulaciÓn de la amÍgdala. El efecto se observa despuÉs de la primera in-yecciÓn de GAG pero su magnitud aumentÓ en dias subsiguientes. Las crisis de comportamiento reaparecieron a los 2–3 dÍas de la interrupciÓn del tratamiento con GAG. La duraciÓn de los ataques electrogrÁficos (perservaciÓn de la post-descarga de la amigdala) no se modificÓ, o incluso aumentÓ, en el primer dia de la administraciÓn de GAG pero se redujo en los dias siguientes. La duraciÓn de las post-descargas volviÓ a sus niveles normales 1 o 2 dias antes que la reapariciÓn de las crisis de comportamiento una vez terminado el tratamiento con GAG. La picrotoxina (1.5-2 mg/kg, i.p.) no antagonizÓ los efectos inhibitorios producidos por el GAG sobre el electroencefalograma o las crisis de comportamiento. La estimulaciÓn elÉctrica sobre la amÍgdala, aplicada durante la fase de sedaciÓn inicial inducida por la picrotoxina, condujo a una regresiÓn aÚn mÁs intensa de las crisis condicionadas, en la mayorÍa de los animales. A pesar de que, con las dosis utilizadas, el GAG alivia las crisis de la amÍgdala previamente condicionada, se requiere gran precauciÓn en su utilizaciÓn en vista de su propiedad de reducir el nivel del despertar. ZUSAMMENFASSUNG Die Wirkung erhÖhter GABA-Spiegel des Gehirns auf AmygdalonkrÄmpfe nach Kindling wurden bei Long-Evans-Ratten untersucht. Der neuerdings synthetisierte GABA-TYansaminasen-Inhibitor, Gamma-Acetylen-GABA (GAG) wurde an 4 aufeinander-folgenden Tagen in einer Dosis von 100 mg/kg und anschlieliend 50 mg/kg i.p. verabfolgt. Er reduzierte entweder signifikant oder eliminierte vÖllig die anfalls-weisen VerhaltensÄnderungen, die normalerweise durch Stimulation des Amygdalon produziert wurden. Die Wirkung ist nach der Erstinjektion des GAG zu beobachten, obgleich ihr Ausmaß an folgenden Tagen grÖßer war. Die VerhaltensanfÄlle kamen 2 bis 3 Tagen nach Beendigung der GAG-Behandlung wieder. Die Dauer der elektrographischen AnfÄlle (sich selbst un-terhaltende Amydalonnachentladungen) blieben entweder gleich oder sie wurden grÖßer am 1. Tag der GAG-Behandlung, wurden aber kÜrzer an folgenden Tagen. Die Dauer der Nachentladungen nor-malisierte sich 1 bis 2 Tage frÜher als die VerhaltensanfÄlle nach Beendigung des GAG verschwanden. Picrotoxin (1.5 bis 2 mg/kg i.p.) wirken nicht als Antagonist gegenÜber der durch GAG produzierten Hemmung der elektrographischen-oder Verhalten-seffekte. Die elektrische Stimulierung des Amygdalon wÄhrend der initialen Sedierung nach Picrotoxin ver-ursachte bei der Mehrzahl der Tiere einen weiteren RÜckgang der durch Kindling entstandenen AnfÄlle. Obgleich das GAG in den verwandten Dosen, die durch Kindling des Amygdalon erzeugten KrÄmpfe leichter ablaufen lUßt, erfordert seine Anwendung Vorsicht hinsichtlich seiner FÄhigkeit, das Erreg-barkeitsniveau zu senken.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66112/1/j.1528-1157.1980.tb04058.x.pd

Differential Dynamics of Transposable Elements during Long-Term Diploidization of Nicotiana Section Repandae (Solanaceae) Allopolyploid Genomes

PubMed ID: 23185607This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

A randomized trial of mail vs. telephone invitation to a community-based cardiovascular health awareness program for older family practice patients [ISRCTN61739603]

BACKGROUND: Family physicians can play an important role in encouraging patients to participate in community-based health promotion initiatives designed to supplement and enhance their in-office care. Our objectives were to determine effective approaches to invite older family practice patients to attend cardiovascular health awareness sessions in community pharmacies, and to assess the feasibility and acceptability of a program incorporating invitation by physicians and feedback to physicians. METHODS: We conducted a prospective randomized trial with 1 family physician practice and 5 community pharmacies in Dundas, Ontario. Regular patients 65 years or older (n = 235) were randomly allocated to invitation by mail or telephone to attend pharmacy cardiovascular health awareness sessions led by volunteer peer health educators. A health record review captured blood pressure status, monitoring and control. At the sessions, volunteers helped patients to measure blood pressure using in-store machines and a validated portable device (BPM-100), and recorded blood pressure readings and self-reported cardiovascular risk factors. We compared attendance rates in the mail and telephone invitation groups and explored factors potentially associated with attendance. RESULTS: The 119 patients invited by mail and 116 patients contacted by telephone had a mean age of 75.7 (SD, 6.4) years and 46.8% were male. Overall, 58.3% (137/235) of invitees attended a pharmacy cardiovascular health awareness session. Patients invited by telephone were more likely to attend than those invited by mail (72.3% vs. 44.0%, OR 3.3; 95%CI 1.9–5.7; p < 0.001). CONCLUSION: While the attendance in response to a telephone invitation was higher, response to a single letter was substantial. Attendance rates indicated considerable interest in community-based cardiovascular health promotion activities. A large-scale trial of a pharmacy cardiovascular health awareness program for older primary care patients is feasible

Reticulated origin of domesticated emmer wheat supports a dynamic model for the emergence of agriculture in the fertile crescent

We used supernetworks with datasets of nuclear gene sequences and novel markers detecting retrotransposon insertions in ribosomal DNA loci to reassess the evolutionary relationships among tetraploid wheats. We show that domesticated emmer has a reticulated genetic ancestry, sharing phylogenetic signals with wild populations from all parts of the wild range. The extent of the genetic reticulation cannot be explained by post-domestication gene flow between cultivated emmer and wild plants, and the phylogenetic relationships among tetraploid wheats are incompatible with simple linear descent of the domesticates from a single wild population. A more parsimonious explanation of the data is that domesticated emmer originates from a hybridized population of different wild lineages. The observed diversity and reticulation patterns indicate that wild emmer evolved in the southern Levant, and that the wild emmer populations in south-eastern Turkey and the Zagros Mountains are relatively recent reticulate descendants of a subset of the Levantine wild populations. Based on our results we propose a new model for the emergence of domesticated emmer. During a pre-domestication period, diverse wild populations were collected from a large area west of the Euphrates and cultivated in mixed stands. Within these cultivated stands, hybridization gave rise to lineages displaying reticulated genealogical relationships with their ancestral populations. Gradual movement of early farmers out of the Levant introduced the pre-domesticated reticulated lineages to the northern and eastern parts of the Fertile Crescent, giving rise to the local wild populations but also facilitating fixation of domestication traits. Our model is consistent with the protracted and dispersed transition to agriculture indicated by the archaeobotanical evidence, and also with previous genetic data affiliating domesticated emmer with the wild populations in southeast Turkey. Unlike other protracted models, we assume that humans played an intuitive role throughout the process.Natural Environment Research Council [NE/E015948/1]; Slovak Research and Development Agency [APVV-0661-10, APVV-0197-10]info:eu-repo/semantics/publishedVersio

Low level methylmercury exposure affects neuropsychological function in adults

BACKGROUND: The neurotoxic effects of methylmercury (MeHg) have been demonstrated in both human and animal studies. Both adult and fetal brains are susceptible to the effects of MeHg toxicity. However, the specific effects of adult exposures have been less well-documented than those of children with prenatal exposures. This is largely because few studies of MeHg exposures in adults have used sensitive neurological endpoints. The present study reports on the results of neuropsychological testing and hair mercury concentrations in adults (>17 yrs) living in fishing communities of Baixada Cuiabana (Mato Grosso) in the Pantanal region of Brazil. METHODS: A cross-sectional study was conducted in six villages on the Cuiaba River. Participants included 129 men and women older than 17 years of age. They were randomly selected in proportion to the age range and number of inhabitants in each village. Questionnaire information was collected on demographic variables, including education, occupation, and residence history. Mercury exposure was determined by analysis of hair using flameless atomic absorption spectrophotometry. The neurocognitive screening battery included tests from the Wechsler Memory Scale and the Wechsler Adult Intelligence Scale, Concentrated Attention Test of the Toulouse-Pierron Factorial Battery, the Manual Ability Subtests of the Tests of Mechanical Ability, and the Profile of Mood States. RESULTS: Mercury exposures in this population were associated with fish consumption. The hair mercury concentration in the 129 subjects ranged from 0.56 to 13.6 μg/g; the mean concentration was 4.2 ± 2.4 micrograms/g and the median was 3.7 μg/g. Hair mercury levels were associated with detectable alterations in performance on tests of fine motor speed and dexterity, and concentration. Some aspects of verbal learning and memory were also disrupted by mercury exposure. The magnitude of the effects increased with hair mercury concentration, consistent with a dose-dependent effect. CONCLUSIONS: This study suggests that adults exposed to MeHg may be at risk for deficits in neurocognitive function. The functions disrupted in adults, namely attention, fine-motor function and verbal memory, are similar to some of those previously reported in children with prenatal exposures