Science.gov

Sample records for 10-week randomized hypo-energetic

  1. Effects of a 10-week inspiratory muscle training program on lower-extremity mobility in people with multiple sclerosis: a randomized controlled trial.

    PubMed

    Pfalzer, Lucinda; Fry, Donna

    2011-01-01

    Pulmonary muscle weakness is common in ambulatory people with multiple sclerosis (MS) and may lead to deficits in mobility function. The purpose of this study was to examine the effect of a 10-week home-based exercise program using an inspiratory muscle threshold trainer (IMT) on the results of four lower-extremity physical performance tests in people with MS. The study design was a two-group (experimental-control), pretest-posttest study. Outcome measures consisted of pulmonary function measures including maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP), and maximal voluntary ventilation (MVV), and the following lower-extremity physical performance measures: the 6-Minute Walk (6MW) distance, gait velocity (GV), the Sit-to-Stand Test (SST), the Functional Stair Test (FST), and a balance test (BAL). A total of 46 ambulatory participants (Expanded Disability Status Scale [EDSS] score, 2.0-6.5) with MS were randomly assigned to an intervention group (mean EDSS score, 4.1) that received 10 weeks of home-based inspiratory muscle training or a nontreatment control group (mean EDSS score, 3.2). Of the original 46 participants, 20 intervention group participants and 19 control group participants completed the study. Compared with the control group, the intervention group made significantly greater gains in inspiratory muscle strength (P = .003) and timed balance scores (P = .008). A nonsignificant improvement in 6MW distance (P = .086) was also noted in the IMT-trained group as compared with the control group. This is the first study directly linking improvement in respiratory function to improvement in physical performance function in people with mild-to-moderate disability due to MS. PMID:24453703

  2. Rabies in a 10-week-old puppy.

    PubMed

    White, Jennifer; Taylor, Susan M; Wolfram, Kathrin L; O'Conner, Brendan P

    2007-09-01

    A 10-week-old, male, border collie-cross puppy was examined for an acute onset of unilateral vestibular signs. Neurologic deterioration was rapid over the next 12 hours and the puppy was euthanized. Rabies was diagnosed by histopathologic and immunohistochemical examination. PMID:17966334

  3. ADHD Symptom Severity following Participation in a Pilot, 10-Week, Manualized, Family-Based Behavioral Intervention

    ERIC Educational Resources Information Center

    Curtis, David F.

    2010-01-01

    This investigation examined the effectiveness of a pilot, manualized 10-week intervention of family skills training for ADHD-related symptoms. The intervention combined behavioral parent training and child focused behavioral activation therapy. Participants were families with children ages 7-10 diagnosed with ADHD-Combined Type. This pilot…

  4. Promoting a Functional Physical Self-Concept in Physical Education: Evaluation of a 10-Week Intervention

    ERIC Educational Resources Information Center

    Schmidt, Mirko; Valkanover, Stefan; Roebers, Claudia; Conzelmann, Achim

    2013-01-01

    Most physical education intervention studies on the positive effect of sports on self-concept development have attempted to "increase" schoolchildren's self-concept without taking the "veridicality" of the self-concept into account. The present study investigated whether a 10-week intervention in physical education would…

  5. Performance enhancement among adolescent players after 10 weeks of pitching training with appropriate baseball weights.

    PubMed

    Yang, Wen-Wen; Liu, Ya-Chen; Lu, Lee-Chang; Chang, Hsiao-Yun; Chou, Paul Pei-Hsi; Liu, Chiang

    2013-12-01

    Compared with regulation-weight baseballs, lightweight baseballs generate lower torque on the shoulder and elbow joints without altering the pitching movement and timing. This study investigates the throwing accuracy, throwing velocity, arm swing velocity, and maximum shoulder external rotation (MSER) of adolescent players after 10 weeks of pitching training with appropriate lightweight baseballs. We assigned 24 adolescent players to a lightweight baseball group (group L) and a regulation-weight baseball group (group R) based on their pretraining throwing velocity. Both groups received pitching training 3 times per week for 10 weeks with 4.4- and 5-oz baseballs. The players' throwing accuracy, throwing velocity, arm swing velocity, and MSER were measured from 10 maximum efforts throws using a regulation-weight baseball before and after undergoing the pitching training. The results showed that the players in group L significantly increased their throwing velocity and arm swing velocity (p < 0.05) after 10 weeks of pitching training with the 4.4-oz baseball, whereas group R did not (p > 0.05). Furthermore, the percentage change in the throwing velocity and arm swing velocity of group L was significantly superior to that of group R (p < 0.05). Thus, we concluded that the 10 weeks of pitching training with an appropriate lightweight baseball substantially enhanced the arm swing velocity and throwing velocity of the adolescent baseball players. These findings suggest that using a lightweight baseball, which can reduce the risk of injury without altering pitching patterns, has positive training effects on players in the rapid physical growth and technique development stage. PMID:23603999

  6. Comparison of upper body strength gains between men and women after 10 weeks of resistance training

    PubMed Central

    Steele, James; Pereira, Maria C.; Castanheira, Rafael P.M.; Paoli, Antonio; Bottaro, Martim

    2016-01-01

    Resistance training (RT) offers benefits to both men and women. However, the studies about the differences between men and women in response to an RT program are not conclusive and few data are available about upper body strength response. The aim of this study was to compare elbow flexor strength gains in men and women after 10 weeks of RT. Forty-four college-aged men (22.63 ± 2.34 years) and forty-seven college-aged women (21.62 ± 2.96 years) participated in the study. The RT program was performed two days a week for 10 weeks. Before and after the training period, peak torque (PT) of the elbow flexors was measured with an isokinetic dynamometer. PT values were higher in men in comparison to women in pre- and post-tests (p < 0.01). Both males and females significantly increased elbow flexor strength (p < 0.05); however, strength changes did not differ between genders after 10 weeks of RT program (11.61 and 11.76% for men and women, respectively; p > 0.05). Effect sizes were 0.57 and 0.56 for men and women, respectively. In conclusion, the present study suggests that men and women have a similar upper body strength response to RT. PMID:26893958

  7. Effects of a 10-Week Inspiratory Muscle Training Program on Lower-Extremity Mobility in People with Multiple Sclerosis

    PubMed Central

    Fry, Donna

    2011-01-01

    Pulmonary muscle weakness is common in ambulatory people with multiple sclerosis (MS) and may lead to deficits in mobility function. The purpose of this study was to examine the effect of a 10-week home-based exercise program using an inspiratory muscle threshold trainer (IMT) on the results of four lower-extremity physical performance tests in people with MS. The study design was a two-group (experimental-control), pretest-posttest study. Outcome measures consisted of pulmonary function measures including maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP), and maximal voluntary ventilation (MVV), and the following lower-extremity physical performance measures: the 6-Minute Walk (6MW) distance, gait velocity (GV), the Sit-to-Stand Test (SST), the Functional Stair Test (FST), and a balance test (BAL). A total of 46 ambulatory participants (Expanded Disability Status Scale [EDSS] score, 2.0–6.5) with MS were randomly assigned to an intervention group (mean EDSS score, 4.1) that received 10 weeks of home-based inspiratory muscle training or a nontreatment control group (mean EDSS score, 3.2). Of the original 46 participants, 20 intervention group participants and 19 control group participants completed the study. Compared with the control group, the intervention group made significantly greater gains in inspiratory muscle strength (P = .003) and timed balance scores (P = .008). A nonsignificant improvement in 6MW distance (P = .086) was also noted in the IMT-trained group as compared with the control group. This is the first study directly linking improvement in respiratory function to improvement in physical performance function in people with mild-to-moderate disability due to MS. PMID:24453703

  8. High-intensity physical training in adults with asthma. A 10-week rehabilitation program.

    PubMed

    Emtner, M; Herala, M; Stålenheim, G

    1996-02-01

    Twenty-six adults (23 to 58 years) with mild to moderate asthma underwent a 10-week supervised rehabilitation program, with emphasis on physical training. In the first 2 weeks, they exercised daily in an indoor swimming pool (33 degrees C) and received education about asthma, medication, and principles of physical training. In the following 8 weeks, they exercised in the pool twice a week. Every training session lasted 45 min. The training sessions were made as suitable as possible for the individual subjects, in order to minimize "drop outs" from the program. The aim of the study was to evaluate the efficacy of the rehabilitation program and to determine if inactive asthmatic adults can exercise at high intensity. The rehabilitation program was preceded by a 6-min submaximal cycle ergometry test, a 12-min walking test, spirometry, and a methacholine provocation test. The subjects also responded to a five-item questionnaire related to anxiety about exercise, breathlessness, and asthma symptoms using a visual analogue scale. All subjects were able to perform physical training at a very high intensity, to 80 to 90% of their predicted maximal heart rate. No asthmatic attacks occurred in connection with the training sessions. Twenty-two of the 26 subjects completed the rehabilitation program, felt confident with physical training, and planned to continue regular physical training after the 10-week program. Improvements in cardiovascular conditioning, measured as a decreased heart rate at the same load on the cycle ergometer (average of 12 beats/min), and as a longer distance at the 12-min walking test (average of 111 m), were observed during the program. FEV1 increased significantly from 2.2 to 2.5 L. Forced expiratory flow at 25% of vital capacity also increased slightly but significantly. Methacholine provocation dose causing a fall in FEV1 by 20% was unchanged. Seventeen subjects had a peak expiratory flow reduction of more than 15% after the preprogram ergometry

  9. Effects of a 10-Week High-Intensity Exercise Intervention on College Staff with Psychological Burnout and Multiple Risk Factors

    ERIC Educational Resources Information Center

    Dreyer, Lukas; Dreyer, Sonja; Rankin, Dean

    2012-01-01

    This study examined the effect of a 10-week physical exercise program on the health status of college staff. Eighty-one participants were pre-tested on 22 variables including physical fitness, biochemical status, psychological health, and morphological measures. Participants in an experimental group (n = 61) received a 10-week intervention…

  10. A 10-Week Multimodal Nutrition Education Intervention Improves Dietary Intake among University Students: Cluster Randomised Controlled Trial.

    PubMed

    Shahril, Mohd Razif; Wan Dali, Wan Putri Elena; Lua, Pei Lin

    2013-01-01

    The aim of the study was to evaluate the effectiveness of implementing multimodal nutrition education intervention (NEI) to improve dietary intake among university students. The design of study used was cluster randomised controlled design at four public universities in East Coast of Malaysia. A total of 417 university students participated in the study. They were randomly selected and assigned into two arms, that is, intervention group (IG) or control group (CG) according to their cluster. The IG received 10-week multimodal intervention using three modes (conventional lecture, brochures, and text messages) while CG did not receive any intervention. Dietary intake was assessed before and after intervention and outcomes reported as nutrient intakes as well as average daily servings of food intake. Analysis of covariance (ANCOVA) and adjusted effect size were used to determine difference in dietary changes between groups and time. Results showed that, compared to CG, participants in IG significantly improved their dietary intake by increasing their energy intake, carbohydrate, calcium, vitamin C and thiamine, fruits and 100% fruit juice, fish, egg, milk, and dairy products while at the same time significantly decreased their processed food intake. In conclusion, multimodal NEI focusing on healthy eating promotion is an effective approach to improve dietary intakes among university students. PMID:24069535

  11. Sensitivity of vergence responses of 5- to 10-week-old human infants.

    PubMed

    Seemiller, Eric S; Wang, Jingyun; Candy, T Rowan

    2016-01-01

    Infants have been shown to make vergence eye movements by 1 month of age to stimulation with prisms or targets moving in depth. However, little is currently understood about the threshold sensitivity of the maturing visual system to such stimulation. In this study, 5- to 10-week-old human infants and adults viewed a target moving in depth as a triangle wave of three amplitudes (1.0, 0.5, and 0.25 meter angles). Their horizontal eye position and the refractive state of both eyes were measured simultaneously. The vergence responses of the infants and adults varied at the same frequency as the stimulus at the three tested modulation amplitudes. For a typical infant of this age, the smallest amplitude is equivalent to an interocular change of approximately 2° of retinal disparity, from nearest to farthest points. The infants' accommodation responses only modulated reliably to the largest stimulus, while adults responded to all three amplitudes. Although the accommodative system appears relatively insensitive, the sensitivity of the vergence responses suggests that subtle cues are available to drive vergence in the second month after birth. PMID:26891827

  12. Physiological responses in rock climbing with repeated ascents over a 10-week period.

    PubMed

    España-Romero, Vanesa; Jensen, Randall L; Sanchez, Xavier; Ostrowski, Megan L; Szekely, Jay E; Watts, Phillip B

    2012-03-01

    The purpose was to analyze the physiological responses and energy expenditure during repeated ascents of the same climbing route over a 10-week period. Nine climbers completed nine ascents of a specific route spaced 1 week apart. Expired air was analyzed continuously during each ascent, and time of ascent was recorded to the nearest second. Energy expenditure during climbing (EE(CLM)), and during climbing +10 min recovery (EE(TOT)) was calculated by the Weir and Zuntz equations. Differences among ascents 1, 4, 6 and 9 were analyzed by repeated measures ANOVA. Climbing time was longer for ascent 1 compared with ascents 4, 6 and 9 (P < 0.001). Differences were found for EE(CLM) (kcal; P < 0.001), between ascent 1 versus 6 and 9 and ascent 4 versus 9, using both Zuntz and Weir equations. Also, differences were observed in EE for recovery (P < 0.05) and EE(TOT) (P < 0.05) using both equations. Repeated ascents of a climbing route decreased the climbing time and absolute energy expenditure during climbing. Initially, the decrease in climbing energy expenditure is accompanied by an increase in energy expenditure during recovery; however, by the ninth ascent, the total energy expenditure of the task is lower than for ascent 1. PMID:21674246

  13. Acute and medium term effects of a 10-week running intervention on mood state in apprentices

    PubMed Central

    Walter, Katrin; von Haaren, Birte; Löffler, Simone; Härtel, Sascha; Jansen, Carl-Philipp; Werner, Christian; Stumpp, Jürgen; Bös, Klaus; Hey, Stefan

    2013-01-01

    Exercise and physical activity have proven benefits for physical and psychological well-being. However, it is not clear if healthy young adults can enhance mood in everyday life through regular exercise. Earlier studies mainly showed positive effects of acute exercise and exercise programs on psychological well-being in children, older people and in clinical populations. Few studies controlled participants' physical activity in daily life, performed besides the exercise program, which can impact results. In addition the transition from mood enhancement induced by acute exercise to medium or long-term effects due to regular exercise is not yet determined. The purpose of this pilot study was to examine the acute effects of an aerobic running training on mood and trends in medium term changes of mood in everyday life of young adults. We conducted a 10-week aerobic endurance training with frequent mood assessments and continuous activity monitoring. 23 apprentices, separated into experimental and control group, were monitored over 12 weeks. To control the effectiveness of the aerobic exercise program, participants completed a progressive treadmill test pre and post the intervention period. The three basic mood dimensions energetic arousal, valence and calmness were assessed via electronic diaries. Participants had to rate their mood state frequently on 3 days a week at five times of measurement within 12 weeks. Participants' physical activity was assessed with accelerometers. All mood dimensions increased immediately after acute endurance exercise but results were not significant. The highest acute mood change could be observed in valence (p = 0.07; η2 = 0.27). However, no medium term effects in mood states could be observed after a few weeks of endurance training. Future studies should focus on the interaction between acute and medium term effects of exercise training on mood. The decreasing compliance over the course of the study requires the development of

  14. Anaerobic power in road cyclists is improved after 10 weeks of whole-body vibration training.

    PubMed

    Oosthuyse, Tanja; Viedge, Alison; McVeigh, Joanne; Avidon, Ingrid

    2013-02-01

    Whole-body vibration (WBV) training has previously improved muscle power in various athletic groups requiring explosive muscle contractions. To evaluate the benefit of including WBV as a training adjunct for improving aerobic and anaerobic cycling performance, road cyclists (n = 9) performed 3 weekly, 10-minute sessions of intermittent WBV on synchronous vertical plates (30 Hz) while standing in a static posture. A control group of cyclists (n = 8) received no WBV training. Before and after the 10-week intervention period, lean body mass (LBM), cycling aerobic peak power (Wmax), 4 mM lactate concentration (OBLA), VO2peak, and Wingate anaerobic peak and mean power output were determined. The WBV group successfully completed all WBV sessions but reported a significant 30% decrease in the weekly cycling training time (pre: 9.4 ± 3.3 h·wk(-1); post: 6.7 ± 3.7 h·wk(-1); p = 0.01) that resulted in a 6% decrease in VO2peak and a 4% decrease in OBLA. The control group reported a nonsignificant 6% decrease in cycling training volume (pre: 9.5 ± 3.6 h·wk(-1); 8.6 ± 2.9 h·wk(-1); p = 0.13), and all measured variables were maintained. Despite the evidence of detraining in the WBV group, Wmax was maintained (pre: 258 ± 53 W; post: 254 ± 57 W; p = 0.43). Furthermore, Wingate peak power increased by 6% (668 ± 189 to 708 ± 220 W; p = 0.055), and Wingate mean power increased by 2% (553 ± 157 to 565 ± 157 W; p = 0.006) in the WBV group from preintervention to postintervention, respectively, without any change to LBM. The WBV training is an attractive training supplement for improving anaerobic power without increasing muscle mass in road cyclists. PMID:22531614

  15. Impact of 10-weeks of yoga practice on flexibility and balance of college athletes

    PubMed Central

    Polsgrove, M Jay; Eggleston, Brandon M; Lockyer, Roch J

    2016-01-01

    Background: With clearer evidence of its benefits, coaches, and athletes may better see that yoga has a role in optimizing performance. Aims: To determine the impact of yoga on male college athletes (N = 26). Methods: Over a 10-week period, a yoga group (YG) of athletes (n = 14) took part in biweekly yoga sessions; while a nonyoga group (NYG) of athletes (n = 12) took part in no additional yoga activity. Performance measures were obtained immediately before and after this period. Measurements of flexibility and balance, included: Sit-reach (SR), shoulder flexibility (SF), and stork stand (SS); dynamic measurements consisted of joint angles (JA) measured during the performance of three distinct yoga positions (downward dog [DD]; right foot lunge [RFL]; chair [C]). Results: Significant gains were observed in the YG for flexibility (SR, P = 0.01; SF, P = 0.03), and balance (SS, P = 0.05). No significant differences were observed in the NYG for flexibility and balance. Significantly, greater JA were observed in the YG for: RFL (dorsiflexion, l-ankle; P = 0.04), DD (extension, r-knee, P = 0.04; r-hip; P = 0.01; flexion, r-shoulder; P = 0.01) and C (flexion, r-knee; P = 0.01). Significant JA differences were observed in the NYG for: DD (flexion, r-knee, P = 0.01: r-hip, P = 0.05; r-shoulder, P = 0.03) and C (flexion r-knee, P = 0.01; extension, r-shoulder; P = 0.05). A between group comparison revealed the significant differences for: RFL (l-ankle; P = 0.01), DD (r-knee, P = 0.01; r-hip; P = 0.01), and C (r-shoulder, P = 0.02). Conclusions: Results suggest that a regular yoga practice may increase the flexibility and balance as well as whole body measures of male college athletes and therefore, may enhance athletic performances that require these characteristics. PMID:26865768

  16. Look in the Mythic Mirror: 10-Week Middle School Curriculum Unit. ArtsEdge Curricula, Lessons and Activities.

    ERIC Educational Resources Information Center

    Ashburn, Jennifer; Ayers, Mary Jane; Born-Ozment, Susan; Karsten, Jayne; Maeda, Sheri

    This 10-week middle school curriculum unit for grades 6-8, integrating concepts, materials, and content from language arts, music, and visual arts, provides a set of specific instructional plans relative to the study of myths (often a content area in middle school grades across the country). All the sample lessons and examples in the curriculum…

  17. Physical and psychological benefits of once-a-week Pilates exercises in young sedentary women: A 10-week longitudinal study.

    PubMed

    Tolnai, Nóra; Szabó, Zsófia; Köteles, Ferenc; Szabo, Attila

    2016-09-01

    Pilates exercises have several demonstrated physical and psychological benefits. To date, most research in this context was conducted with symptomatic or elderly people with few dependent measures. The current study examined the chronic or longitudinal effects of very low frequency, once a week, Pilates training on several physical and psychological measures, over a 10-week intervention, in young, healthy, and sedentary women. Further, the study gauged the acute effects of Pilates exercises on positive- and negative affect in 10 exercise sessions. Compared to a control group, the Pilates group exhibited significant improvements in skeletal muscle mass, flexibility, balance, core- and abdominal muscle strength, body awareness, and negative affect. This group also showed favorable changes in positive (22.5% increase) and negative affect (12.2% decrease) in nine out of ten exercise sessions. This work clearly demonstrates the acute and chronic benefits of Pilates training on both physical and psychological measures. It also reveals that even only once a week Pilates training is enough to trigger detectable benefits in young sedentary women. While this frequency is below the required levels of exercise for health, it may overcome the 'lack of time' excuse for not exercising and subsequently its tangible benefits may positively influence one's engagement in more physical activity. PMID:27195456

  18. Laparoscopic Excision of a Pedunculated Uterine Leiomyoma in Torsion as a Cause of Acute Abdomen at 10 Weeks of Pregnancy

    PubMed Central

    Kosmidis, Christophoros; Pantos, George; Efthimiadis, Christopher; Gkoutziomitrou, Ioanna; Georgakoudi, Eleni; Anthimidis, George

    2015-01-01

    Patient: Female, 31 Final Diagnosis: Acute abdomen due to pedunculated uterine leiomyoma in torsion Symptoms: Abdominal pain • vomiting Medication: Cefoxitin 2gr Clinical Procedure: Laparoscopic excision of the pendunculated uterine leiomyoma – laparoscopic appedicectomy Specialty: Surgery Objective: Unusual clinical course Background: Pregnancy outcomes after laparoscopic myomectomy are generally favorable, with a pregnancy rate that is comparable to or even higher than the rate associated with abdominal myomectomy. The purpose of this article is to present the case of a pregnant patient at 10 weeks of gestation who was submitted to successful laparoscopic myomectomy of a twisted pedunculated uterine leiomyoma. Case Report: A 31 year-old Greek pregnant woman complaining about acute abdominal pain was submitted to diagnostic laparoscopy which revealed a huge twisted uterine leiomyoma. Subsequently laparoscopic myomectomy was successfully carried out. Conclusions: Laparoscopic myomectomy is a technically challenging procedure with surgeon-specific limitations. Laparoscopy during pregnancy should be performed with utmost care and it proves to be a safe and effective procedure in hands of clinicians with sufficient experience in laparoscopic surgery. PMID:26227425

  19. Effect of a 10-week yoga programme on the quality of life of women after breast cancer surgery

    PubMed Central

    Merecz, Dorota; Wójcik, Aleksandra; Świątkowska, Beata; Sierocka, Kamilla; Najder, Anna

    2014-01-01

    Aim of the study The following research is aimed at determining the effect of yoga on the quality of life of women after breast cancer surgery. Material and methods A 10-week yoga programme included 90-minute yoga lessons once a week. To estimate the quality of life, questionnaires developed by the European Organisation for Research and Treatment of Cancer (QLQ-C30 and QLQ-BR23) were used. An experimental group consisted of 12 women who practised yoga, a control group – of 16 women who did not. Between groups there were no differences in age, time from operation and characteristics associated with disease, treatment and participation in rehabilitation. Results Our results revealed an improvement of general health and quality of life, physical and social functioning as well as a reduction of difficulties in daily activities among exercising women. Also their future prospects enhanced – they worried less about their health than they used to before participating in the programme. As compared to baseline, among exercising women, fatigue, dyspnoea and discomfort (pain, swelling, sensitivity) in the arm and breast on the operated side decreased. Conclusions Participation in the exercising programme resulted in an improvement of physical functioning, reduction of fatigue, dyspnoea, and discomfort in the area of the breast and arm on the operated side. Based on our results and those obtained in foreign studies, we conclude that rehabilitation with the use of yoga practice improves the quality of life of the patients after breast cancer surgery. However, we recommend further research on this issue in Poland. PMID:26327853

  20. Effects of 10-week eccentric overload training on kinetic parameters during change of direction in football players.

    PubMed

    de Hoyo, Moisés; Sañudo, Borja; Carrasco, Luis; Mateo-Cortes, Jesús; Domínguez-Cobo, Sergio; Fernandes, Orlando; Del Ojo, Juan J; Gonzalo-Skok, Oliver

    2016-07-01

    The aim of the current study was to analyse the effect of 10-week eccentric overload training on kinetic parameters during change of direction (COD) in U-19 football players. The outcome measured included relative peak braking (rPB) and propulsive force (rPF), contact time (CT), time spent during braking (BT) and propulsive phase (PT), relative total (rTOT_IMP), braking (rB_IMP) and propulsive (rP_IMP) impulses. Between-group results showed a substantial better improvement (likely) in CT (ES: 0.72) and BT (ES: 0.74) during side-step cutting, and in rPB (ES: 0.84) and rB_IMP (ES: 0.72) during crossover cutting, in the experimental group (EXP) in comparison to control group (CON). Within-group analysis showed a substantially better performance (likely to almost certain) in CT (ES: 1.19), BT (ES: 1.24), PT (ES: 0.70), rPB (ES: 0.75), rPF (ES: 0.68), rTOT_IMP (ES: 0.48) and rB_IMP (ES: 0.50) in EXP during side-step cutting. Regarding crossover cutting, within-group analysis showed a substantial better performance (likely to almost certain) in CT (ES: 0.75), rPB (ES: 0.75), rPF (ES: 1.34), rTOT_IMP (ES: 0.61), rB_IMP (ES: 0.76) and rP_IMP (ES: 0.46) in EXP. In conclusion, the eccentric overload-based programme led to an improvement in kinetic parameters during COD football tasks. PMID:26963941

  1. Vitamin C and E supplementation alters protein signalling after a strength training session, but not muscle growth during 10 weeks of training

    PubMed Central

    Paulsen, G; Hamarsland, H; Cumming, K T; Johansen, R E; Hulmi, J J; Børsheim, E; Wiig, H; Garthe, I; Raastad, T

    2014-01-01

    This study investigated the effects of vitamin C and E supplementation on acute responses and adaptations to strength training. Thirty-two recreationally strength-trained men and women were randomly allocated to receive a vitamin C and E supplement (1000 mg day−1 and 235 mg day−1, respectively), or a placebo, for 10 weeks. During this period the participants’ training involved heavy-load resistance exercise four times per week. Muscle biopsies from m. vastus lateralis were collected, and 1 repetition maximum (1RM) and maximal isometric voluntary contraction force, body composition (dual-energy X-ray absorptiometry), and muscle cross-sectional area (magnetic resonance imaging) were measured before and after the intervention. Furthermore, the cellular responses to a single exercise session were assessed midway in the training period by measurements of muscle protein fractional synthetic rate and phosphorylation of several hypertrophic signalling proteins. Muscle biopsies were obtained from m. vastus lateralis twice before, and 100 and 150 min after, the exercise session (4 × 8RM, leg press and knee-extension). The supplementation did not affect the increase in muscle mass or the acute change in protein synthesis, but it hampered certain strength increases (biceps curl). Moreover, increased phosphorylation of p38 mitogen-activated protein kinase, Extracellular signal-regulated protein kinases 1 and 2 and p70S6 kinase after the exercise session was blunted by vitamin C and E supplementation. The total ubiquitination levels after the exercise session, however, were lower with vitamin C and E than placebo. We concluded that vitamin C and E supplementation interfered with the acute cellular response to heavy-load resistance exercise and demonstrated tentative long-term negative effects on adaptation to strength training. PMID:25384788

  2. Tolerating Uncertainty: The Exploration of a 10-Week Stress Management Course which Supports a Process of Recovery, Personal Change and Educational Development for People Experiencing Stress and Anxiety.

    ERIC Educational Resources Information Center

    Smith, Sue

    2002-01-01

    A 10-week stress management and relaxation course helped anxious students develop skills and strategies derived from self-awareness. Course included stress theory, organizational skills (time management, goal setting), personal transformation, tolerance for uncertainty, and metacognition, with an emphasis on self-efficacy and autonomy. (Contains…

  3. A Comparison of Student Outcomes and Overall Retention between a 10-Week Accelerated and a 15-Week Traditional Curriculum in a Postsecondary Apprenticeship Training Program

    ERIC Educational Resources Information Center

    Adams, Gilbert L.

    2013-01-01

    This ex post facto comparison study of a postsecondary apprenticeship program at a naval ship construction company examined 8 years of academic performance and program completion data for two curricular formats: a 15-week traditional group (1,259 apprentices) and a 10-week accelerated group (736 apprentices). The two groups were investigated to…

  4. Effect of a 10-week traditional dance program on static and dynamic balance control in elderly adults.

    PubMed

    Sofianidis, Giorgos; Hatzitaki, Vassilia; Douka, Stella; Grouios, Giorgos

    2009-04-01

    This preliminary study examined the effect of a 10-wk traditional Greek dance program on static and dynamic balance indices in healthy elderly adults. Twenty-six community-dwelling older adults were randomly assigned to either an intervention group who took supervised Greek traditional dance classes for 10 wk (1 hr, 2 sessions/week, n = 14), or a control group (n = 12). Balance was assessed pre- and postintervention by recording the center-of-pressure (COP) variations and trunk kinematics during performance of the Sharpened-Romberg test, 1-leg (OL) stance, and dynamic weight shifting (WS). After practice, the dance group significantly decreased COP displacement and trunk sway in OL stance. A significant increase in the range of trunk rotation was noted during performance of dynamic WS in the sagittal and frontal planes. These findings support the use of traditional dance as an effective means of physical activity for improving static and dynamic balance control in the elderly. PMID:19451666

  5. High specification starter diets improve the performance of low birth weight pigs to 10 weeks of age.

    PubMed

    Douglas, S L; Wellock, I; Edwards, S A; Kyriazakis, I

    2014-10-01

    Piglets born with low birth weights (LBiW) are likely to be lighter at weaning. Starter regimes tailored for pigs of average BW therefore may not be optimal for LBiW nursery performance. The objective was to determine if LBiW pigs benefit from a high specification starter regime and the provision of extra feed (additional allowance of last phase diet of the starter regime) in comparison to a standard commercial regime. Additionally, the effect of starter regime on performance of normal birth weight (NBiW) pigs at weaning was determined and compared to that of LBiW pigs. Finally, the cost effectiveness of the treatments was determined. The experiment was therefore an incomplete 2 × 2 × 2 factorial design, as the provision of extra feed was given only to LBiW pigs (n = 6 replicates per treatment; 5 pigs per replicate). Treatments comprised birth weight (LBiW or NBiW), starter regime (high specification [HS] or standard starter [SS]), and extra feed 3 quantity (yes [YF] or no [NF], for LBiW pigs only; feed 3 corresponded to the last phase diet of the starter regime). At weaning (d 28), pigs were randomly assigned within each birth weight category to treatment groups. Nutritional treatments were fed ad libitum on a kilogram/head basis for approximately 3 wk followed by a common weaner diet fed ad libitum until d 70. Starter regime (P = 0.019), feed 3 amount (P = 0.010), and their interaction (P = 0.029) had an effect on ADG of LBiW pigs from d 28 to 49, with pigs on HS followed by YF (HY) performing best. An improvement in feed conversion ratio (FCR) was noted between d 28 and 49 for pigs fed the additional feed 3 (P = 0.030); between d 49 and 70, the only residual effect seen was of starter regime (P = 0.017) on ADG. In contrast, there was no significant effect of starter regime from d 28 to 70 on ADG, ADFI, or FCR of NBiW pigs. By d 49 and 70, LBiW pigs on regime HY weighed the same as NBiW pigs (d 70 BW; 30.0 vs. 30.6 kg; P = 0.413), with similar growth rates from

  6. Further decrease in glycated hemoglobin following ingestion of a LoBAG30 diet for 10 weeks compared to 5 weeks in people with untreated type 2 diabetes

    PubMed Central

    2010-01-01

    Background We previously determined that a weight-maintenance, non-ketogenic diet containing 30% carbohydrate (CHO), 30% protein, 40% fat, (30:30:40) (LoBAG30) decreased glycated hemoglobin (%tGHb) from 10.8 to 9.1% over a 5 week period in subjects with untreated type 2 diabetes. Both the fasting glucose and postprandial glucose area were decreased. Our objective in the present 10-week study was to determine: 1) whether the above results could be maintained, or even improved (suggesting a metabolic adaptation) and 2) whether the subjects would accept the diet for this longer time period. In addition, protein balance, and a number of other blood and urine constituents were quantified at 5 and at 10 weeks on the LoBAG30 diet to address metabolic adaptation. Methods Eight men with untreated type 2 diabetes were studied over a 10-week period. Blood was drawn and urine was collected over a 24 hour period at the beginning of the study with subjects ingesting a standard diet of 55% CHO, 15% protein, 30% fat, and at the end of 5 and 10 weeks following ingestion of a LoBAG30 diet. Results Body weight was stable. Fasting glucose decreased by 19% at week 5 and 28% at week 10; 24-h total glucose area decreased by 27% at week 5 and 35% at week 10 compared to baseline. Insulin did not change. Mean %tGHb decreased by 13% at week 5, 25% at week 10, and was still decreasing linearly, indicating that a metabolic adaptation occurred. Serum NEFA, AAN, uric acid, urea, albumin, prealbumin, TSH, Total T3, free T4, B12, folate, homocysteine, creatinine, growth hormone and renin did not differ between weeks 5 and 10. IGF-1 increased modestly. Urinary glucose decreased; urinary pH and calcium were similar. Conclusions A LoBAG30 diet resulted in continued improvement in glycemic control. This improvement occurred without significant weight loss, with unchanged insulin and glucagon profiles, and without deterioration in serum lipids, blood pressure or kidney function. Extending the duration

  7. The effects of 10 weeks of resistance training combined with beta-alanine supplementation on whole body strength, force production, muscular endurance and body composition.

    PubMed

    Kendrick, Iain P; Harris, Roger C; Kim, Hyo Jeong; Kim, Chang Keun; Dang, Viet H; Lam, Thanh Q; Bui, Toai T; Smith, Marcus; Wise, John A

    2008-05-01

    Carnosine (Carn) occurs in high concentrations in skeletal muscle is a potent physico-chemical buffer of H+ over the physiological range. Recent research has demonstrated that 6.4 g x day(-1) of beta-alanine (beta-ala) can significantly increase skeletal muscle Carn concentrations (M-[Carn]) whilst the resultant change in buffering capacity has been shown to be paralleled by significant improvements in anaerobic and aerobic measures of exercise performance. Muscle carnosine increase has also been linked to increased work done during resistance training. Prior research has suggested that strength training may also increase M-[Carn] although this is disputed by other studies. The aim of this investigation is to assess the effect of 10 weeks resistance training on M-[Carn], and, secondly, to investigate if increased M-[Carn] brought about through beta-ala supplementation had a positive effect on training responses. Twenty-six Vietnamese sports science students completed the study. The subjects completed a 10-week resistance-training program whilst consuming 6.4 g x day(-1) of beta-ala (beta-ALG) or a matched dose of a placebo (PLG). Subjects were assessed prior to and after training for whole body strength, isokinetic force production, muscular endurance, body composition. beta-Alanine supplemented subjects increased M-[Carn] by 12.81 +/- 7.97 mmol x kg(-1) dry muscle whilst there was no change in PLG subjects. There was no significant effect of beta-ala supplementation on any of the exercise parameters measured, mass or % body fat. In conclusion, 10 weeks of resistance training alone did not change M-[Carn]. PMID:18175046

  8. Significant progression of load on the musculoskeletal system with extremely high loads, with rapid weekly weight gains, using the Anatoly Gravitational System, in a 10-week training period.

    PubMed

    Burke, David T; Tran, David; Cui, Di; Burke, Daniel P; Al-Adawi, Samir; Dorvlo, Atsu Ss

    2013-01-01

    In an age of increasing numbers of lifestyle diseases and plasticity of longevity, exercise and weight training have been increasingly recognized as both preventing and mitigating the severity of many illnesses. This study was designed to determine whether significant weight-lifting gains could be realized through the Anatoly Gravitational System. Specifically, this study sought to determine whether this once-weekly weight-training system could result in significant weekly strength gains during a 10-week training period. A total of 50 participants, ranging in age from 17 to 67 years, completed at least 10 weekly 30-minute training sessions. The results suggest participants could, on average, double their weight-lifting capacity within 10 sessions. This preliminary study, which would require further scrutiny, suggests the Anatoly Gravitational System provides a rather unique opportunity to load the musculoskeletal system with extremely high loads, with rapid weekly weight gains, using only short weekly training sessions. More studies are warranted to scrutinize these findings. PMID:24379727

  9. A 10-week memantine treatment in bipolar depression: a case report. Focus on depressive symptomatology, cognitive parameters and quality of life.

    PubMed

    Strzelecki, Dominik; Tabaszewska, Agnieszka; Barszcz, Zbigniew; Józefowicz, Olga; Kropiwnicki, Paweł; Rabe-Jabłońska, Jolanta

    2013-12-01

    Memantine and other glutamatergic agents have been currently investigated in some off-label indications due to glutamatergic involvement in several psychoneurological disorders. We assumed that memantine similarly to ketamine may positively influence mood, moreover having a potential to improve cognition and general quality of life. We report a case of a 49-year-old male hospitalized during a manic and a subsequent moderate depressive episode. After an ineffective use of lithium, olanzapine and antidepressive treatment with mianserin, memantine was added up to 20 mg per day for 10 weeks. The mental state was assessed using the Hamilton Depression Rating Scale, the Young Mania Rating Scale, the Hamilton Anxiety Scale, the Clinical Global Inventory, the World Health Organization Quality of Life Scale and psychological tests. After 10 weeks the patient achieved a partial symptomatic improvement in mood, anxiety and quality of sleep, but his activity remained insufficient. We also observed an improvement in the parameters of cognitive functioning and quality of life. There was neither significant mood variations during the memantine use nor mood changes after its termination. No significant side effects were noted during the memantine treatment. We conclude that using memantine in bipolar depression may improve mood, cognitive functioning and quality of life. PMID:24474993

  10. Effects of in utero exposure to cyclophosphamide in mice. II. Assessment of immunocompetence of offspring from 5 to 10 weeks of age

    SciTech Connect

    Liakopoulou, A.; Buttar, H.S.; Nera, E.A.; Fernando, L. )

    1989-01-01

    Offspring of mice treated with cyclophosphamide (Cy; 1, 2.5 or 5 mg/kg) during pregnancy (6-18 days of gestation) and tested for immunocompetence from 5 to 10 weeks of age were found to have defective reticuloendothelial clearance. The main effects were: (a) increased elimination half time (T 1/2) of {sup 51}Cr-labeled SRBC from circulation, (b) decreased liver uptake of {sup 51}Cr and (c) impaired ability of the spleen, mostly affecting the female pups, to compensate for decreased liver uptake. The highest dose group suffered the most pronounced effects. This group was also found to have increased IgG immunoglobulin levels at 7 weeks of age. IgG antibody production in response to specific antigenic stimulation and delayed hypersensitivity reactions to oxazolone did not appear to be affected by Cy treatment.

  11. Improvement of insulin resistance after diet with a whole-grain based dietary product: results of a randomized, controlled cross-over study in obese subjects with elevated fasting blood glucose.

    PubMed

    Rave, Klaus; Roggen, Kerstin; Dellweg, Sibylle; Heise, Tim; tom Dieck, Heike

    2007-11-01

    Subjects with obesity and elevated fasting blood glucose are at high risk of developing type 2 diabetes which may be reduced by a dietary intervention leading to an improvement of insulin resistance. We investigated the potential of a whole-grain based dietary product (WG) with reduced starch content derived from double-fermented wheat during a hypo-energetic diet to positively influence body weight, fasting blood glucose, insulin resistance and lipids in comparison to a nutrient-dense meal replacement product (MR) in a randomized two-way cross-over study with two 4-week treatment periods separated by a 2-week wash-out. Subjects replaced at least two daily meals with WG and MR, respectively, targeting for a consumption of 200 g of either product per day. Total daily energy intake was limited to 7120 kJ. Thirty-one subjects (BMI 33.9 (SD 2.7) kg/m2, fasting blood glucose 6.3 (SD 0.8) mmol/l) completed the study. In both treatment groups body weight (-2.5 (SD 2.0) v. - 3.2 (SD 1.6) kg for WG v. MR), fasting blood glucose (-0.4 (SD 0.3) v. -0.5 (SD 0.5) mmol/l), total cholesterol (-0.5 (SD 0.5) v. -0.6 (SD 0.5) mmol/l), TAG (-0.3 (SD 0.9) v. -0.3 (SD 1.2) mmol/l) and homeostasis model assessment (HOMA) insulin resistance score (-0.7 (SD 0.8) v. -1.1 (SD 1.7) microU/ml x mmol/l) improved (P < 0.05) with no significant differences between the treatments. After statistical adjustment for the amount of body weight lost, however, the comparison between both groups revealed that fasting serum insulin (P = 0.031) and HOMA insulin resistance score (P = 0.049) improved better with WG than with MR. We conclude that WG favourably influences metabolic risk factors for type 2 diabetes independent from the amount of body weight lost during a hypo-energetic diet. PMID:17562226

  12. Place-based research project design for 10-week REU and two-week "mini-REU" internships using lake sediment cores

    NASA Astrophysics Data System (ADS)

    Myrbo, A.; Howes, T.; Thompson, R.; Drake, C.; Woods, P.; Schuldt, N.; Borkholder, B.; Marty, J.; Lafrancois, T.; Pellerin, H.

    2012-12-01

    . The two-week "mini-REU" was designed to attract students with little or no independent research experience, who might be intimidated by applying for a ten-week internship away from home (but who might apply for one after completing a good mini-REU). The arc of research, from site selection to field work and lab work to data interpretation and poster presentation, must be encompassed in these brief projects, so group projects with clear goals are best suited for mini-REUs. The May 2012 project, with twelve students in four research proxy groups (charcoal, phytoliths, plant macrofossils, and zooplankton), demonstrated that a FDL lake, Rice Portage, had extensive wild rice habitat prior to early 20th-century Euroamerican ditching; this proof was required in order for FDL to gain a permit from the Army Corps of Engineers to raise the lake level as part of a wild rice restoration effort. Each proxy group had one research advisor (a graduate student or soft money researcher), plus one UMN über-advisor for the project as a whole, as well as the Fond du Lac resource manager. All of these advisors also work with the 10-week interns throughout the summer.

  13. Changes in Bone Biomarkers, BMC, and Insulin Resistance Following a 10-Week Whole Body Vibration Exercise Program in Overweight Latino Boys

    PubMed Central

    Erceg, David N.; Anderson, Lindsey J.; Nickles, Chun M.; Lane, Christianne J.; Weigensberg, Marc J.; Schroeder, E. Todd

    2015-01-01

    Purpose: With the childhood obesity epidemic, efficient methods of exercise are sought to improve health. We tested whether whole body vibration (WBV) exercise can positively affect bone metabolism and improve insulin/glucose dynamics in sedentary overweight Latino boys. Methods: Twenty Latino boys 8-10 years of age were randomly assigned to either a control (CON) or 3 days/wk WBV exercise (VIB) for 10-wk. Results: Significant increases in BMC (4.5±3.2%; p=0.01) and BMD (1.3±1.3%; p<0.01) were observed for the VIB group when compared to baseline values. For the CON group BMC significantly increased (2.0±2.2%; p=0.02), with no change in BMD (0.8±1.3%; p=0.11). There were no significant between group changes in BMC or BMD. No significant change was observed for osteocalcin and (collagen type I C-telopeptide) CTx for the VIB group. However, osteocalcin showed a decreasing trend (p=0.09) and CTx significantly increased (p<0.03) for the CON group. This increase in CTx was significantly different between groups (p<0.02) and the effect size of between-group difference in change was large (-1.09). There were no significant correlations between osteocalcin and measures of fat mass or insulin resistance for collapsed data. Conclusion: Although bone metabolism was altered by WBV training, no associations were apparent between osteocalcin and insulin resistance. These findings suggest WBV exercise may positively increase BMC and BMD by decreasing bone resorption in overweight Latino boys. PMID:26078710

  14. Random Walks on Random Graphs

    NASA Astrophysics Data System (ADS)

    Cooper, Colin; Frieze, Alan

    The aim of this article is to discuss some of the notions and applications of random walks on finite graphs, especially as they apply to random graphs. In this section we give some basic definitions, in Section 2 we review applications of random walks in computer science, and in Section 3 we focus on walks in random graphs.

  15. Feasibility and Preliminary Efficacy of an After-School Program for Middle Schoolers with ADHD: A Randomized Trial in a Large Public Middle School

    ERIC Educational Resources Information Center

    Molina, Brooke S. G.; Flory, Kate; Bukstein, Oscar G.; Greiner, Andrew R.; Baker, Jennifer L.; Krug, Vicky; Evans, Steven W.

    2008-01-01

    Objective: This pilot study tests the feasibility and preliminary efficacy of an after-school treatment program for middle schoolers with ADHD using a randomized clinical trial design. Method: A total of 23 students with ADHD (25% female, 48% African American) from a large public middle school were randomly assigned to a 10-week program or to…

  16. Random thoughts

    NASA Astrophysics Data System (ADS)

    ajansen; kwhitefoot; panteltje1; edprochak; sudhakar, the

    2014-07-01

    In reply to the physicsworld.com news story “How to make a quantum random-number generator from a mobile phone” (16 May, http://ow.ly/xFiYc, see also p5), which describes a way of delivering random numbers by counting the number of photons that impinge on each of the individual pixels in the camera of a Nokia N9 smartphone.

  17. Random Vibrations

    NASA Technical Reports Server (NTRS)

    Messaro. Semma; Harrison, Phillip

    2010-01-01

    Ares I Zonal Random vibration environments due to acoustic impingement and combustion processes are develop for liftoff, ascent and reentry. Random Vibration test criteria for Ares I Upper Stage pyrotechnic components are developed by enveloping the applicable zonal environments where each component is located. Random vibration tests will be conducted to assure that these components will survive and function appropriately after exposure to the expected vibration environments. Methodology: Random Vibration test criteria for Ares I Upper Stage pyrotechnic components were desired that would envelope all the applicable environments where each component was located. Applicable Ares I Vehicle drawings and design information needed to be assessed to determine the location(s) for each component on the Ares I Upper Stage. Design and test criteria needed to be developed by plotting and enveloping the applicable environments using Microsoft Excel Spreadsheet Software and documenting them in a report Using Microsoft Word Processing Software. Conclusion: Random vibration liftoff, ascent, and green run design & test criteria for the Upper Stage Pyrotechnic Components were developed by using Microsoft Excel to envelope zonal environments applicable to each component. Results were transferred from Excel into a report using Microsoft Word. After the report is reviewed and edited by my mentor it will be submitted for publication as an attachment to a memorandum. Pyrotechnic component designers will extract criteria from my report for incorporation into the design and test specifications for components. Eventually the hardware will be tested to the environments I developed to assure that the components will survive and function appropriately after exposure to the expected vibration environments.

  18. Behavioral Outcome Effects of Serious Gaming as an Adjunct to Treatment for Children With Attention-Deficit/Hyperactivity Disorder: A Randomized Controlled Trial

    PubMed Central

    2016-01-01

    Background The need for accessible and motivating treatment approaches within mental health has led to the development of an Internet-based serious game intervention (called “Plan-It Commander”) as an adjunct to treatment as usual for children with attention-deficit/hyperactivity disorder (ADHD). Objective The aim was to determine the effects of Plan-It Commander on daily life skills of children with ADHD in a multisite randomized controlled crossover open-label trial. Methods Participants (N=170) in this 20-week trial had a diagnosis of ADHD and ranged in age from 8 to 12 years (male: 80.6%, 137/170; female: 19.4%, 33/170). They were randomized to a serious game intervention group (group 1; n=88) or a treatment-as-usual crossover group (group 2; n=82). Participants randomized to group 1 received a serious game intervention in addition to treatment as usual for the first 10 weeks and then received treatment as usual for the next 10 weeks. Participants randomized to group 2 received treatment as usual for the first 10 weeks and crossed over to the serious game intervention in addition to treatment as usual for the subsequent 10 weeks. Primary (parent report) and secondary (parent, teacher, and child self-report) outcome measures were administered at baseline, 10 weeks, and 10-week follow-up. Results After 10 weeks, participants in group 1 compared to group 2 achieved significantly greater improvements on the primary outcome of time management skills (parent-reported; P=.004) and on secondary outcomes of the social skill of responsibility (parent-reported; P=.04), and working memory (parent-reported; P=.02). Parents and teachers reported that total social skills improved over time within groups, whereas effects on total social skills and teacher-reported planning/organizing skills were nonsignificant between groups. Within group 1, positive effects were maintained or further improved in the last 10 weeks of the study. Participants in group 2, who played the

  19. RANDOM LASSO.

    PubMed

    Wang, Sijian; Nan, Bin; Rosset, Saharon; Zhu, Ji

    2011-03-01

    We propose a computationally intensive method, the random lasso method, for variable selection in linear models. The method consists of two major steps. In step 1, the lasso method is applied to many bootstrap samples, each using a set of randomly selected covariates. A measure of importance is yielded from this step for each covariate. In step 2, a similar procedure to the first step is implemented with the exception that for each bootstrap sample, a subset of covariates is randomly selected with unequal selection probabilities determined by the covariates' importance. Adaptive lasso may be used in the second step with weights determined by the importance measures. The final set of covariates and their coefficients are determined by averaging bootstrap results obtained from step 2. The proposed method alleviates some of the limitations of lasso, elastic-net and related methods noted especially in the context of microarray data analysis: it tends to remove highly correlated variables altogether or select them all, and maintains maximal flexibility in estimating their coefficients, particularly with different signs; the number of selected variables is no longer limited by the sample size; and the resulting prediction accuracy is competitive or superior compared to the alternatives. We illustrate the proposed method by extensive simulation studies. The proposed method is also applied to a Glioblastoma microarray data analysis. PMID:22997542

  20. 10 Days or 10 Weeks: Immersion Programs That Work.

    ERIC Educational Resources Information Center

    Troiani, Elisa A.

    The foreign language faculty at College of Saint Scholastica Minnesota) developed and implemented 10-day Spanish and French immersion programs based on Peace Corps methodology as a means of affording students time for intensive study of those languages, improving students' fluency, and instituting a change in teaching methodology. The first…

  1. Is random access memory random?

    NASA Technical Reports Server (NTRS)

    Denning, P. J.

    1986-01-01

    Most software is contructed on the assumption that the programs and data are stored in random access memory (RAM). Physical limitations on the relative speeds of processor and memory elements lead to a variety of memory organizations that match processor addressing rate with memory service rate. These include interleaved and cached memory. A very high fraction of a processor's address requests can be satified from the cache without reference to the main memory. The cache requests information from main memory in blocks that can be transferred at the full memory speed. Programmers who organize algorithms for locality can realize the highest performance from these computers.

  2. Random broadcast on random geometric graphs

    SciTech Connect

    Bradonjic, Milan; Elsasser, Robert; Friedrich, Tobias

    2009-01-01

    In this work, we consider the random broadcast time on random geometric graphs (RGGs). The classic random broadcast model, also known as push algorithm, is defined as: starting with one informed node, in each succeeding round every informed node chooses one of its neighbors uniformly at random and informs it. We consider the random broadcast time on RGGs, when with high probability: (i) RGG is connected, (ii) when there exists the giant component in RGG. We show that the random broadcast time is bounded by {Omicron}({radical} n + diam(component)), where diam(component) is a diameter of the entire graph, or the giant component, for the regimes (i), or (ii), respectively. In other words, for both regimes, we derive the broadcast time to be {Theta}(diam(G)), which is asymptotically optimal.

  3. Quantumness, Randomness and Computability

    NASA Astrophysics Data System (ADS)

    Solis, Aldo; Hirsch, Jorge G.

    2015-06-01

    Randomness plays a central role in the quantum mechanical description of our interactions. We review the relationship between the violation of Bell inequalities, non signaling and randomness. We discuss the challenge in defining a random string, and show that algorithmic information theory provides a necessary condition for randomness using Borel normality. We close with a view on incomputablity and its implications in physics.

  4. How random is a random vector?

    NASA Astrophysics Data System (ADS)

    Eliazar, Iddo

    2015-12-01

    Over 80 years ago Samuel Wilks proposed that the "generalized variance" of a random vector is the determinant of its covariance matrix. To date, the notion and use of the generalized variance is confined only to very specific niches in statistics. In this paper we establish that the "Wilks standard deviation" -the square root of the generalized variance-is indeed the standard deviation of a random vector. We further establish that the "uncorrelation index" -a derivative of the Wilks standard deviation-is a measure of the overall correlation between the components of a random vector. Both the Wilks standard deviation and the uncorrelation index are, respectively, special cases of two general notions that we introduce: "randomness measures" and "independence indices" of random vectors. In turn, these general notions give rise to "randomness diagrams"-tangible planar visualizations that answer the question: How random is a random vector? The notion of "independence indices" yields a novel measure of correlation for Lévy laws. In general, the concepts and results presented in this paper are applicable to any field of science and engineering with random-vectors empirical data.

  5. Psychological and cognitive outcomes of a randomized trial of exercise among patients with chronic obstructive pulmonary disease.

    PubMed

    Emery, C F; Schein, R L; Hauck, E R; MacIntyre, N R

    1998-05-01

    Exercise rehabilitation is recommended increasingly for patients with chronic obstructive pulmonary disease (COPD). This study examined the effect of exercise and education on 79 older adults (M age = 66.6 +/- 6.5 years; 53% female) with COPD, randomly assigned to 10 weeks of (a) exercise, education, and stress management (EXESM; n = 29); (b) education and stress management (ESM; n = 25); or (c) waiting list (WL; n = 25). EXESM included 37 sessions of exercise, 16 educational lectures, and 10 weekly stress management classes. ESM included only the 16 lectures and 10 stress management classes. Before and after the intervention, assessments were conducted of physiological functioning (pulmonary function, exercise endurance), psychological well-being (depression, anxiety, quality of life), and cognitive functioning (attention, motor speed, mental efficiency, verbal processing). Repeated measures multivariate analysis of variance indicated that EXESM participants experienced changes not observed among ESM and WL participants, including improved endurance, reduced anxiety, and improved cognitive performance (verbal fluency). PMID:9619472

  6. Comparing MTI randomization procedures to blocked randomization.

    PubMed

    Berger, Vance W; Bejleri, Klejda; Agnor, Rebecca

    2016-02-28

    Randomization is one of the cornerstones of the randomized clinical trial, and there is no shortage of methods one can use to randomize patients to treatment groups. When deciding which one to use, researchers must bear in mind that not all randomization procedures are equally adept at achieving the objective of randomization, namely, balanced treatment groups. One threat is chronological bias, and permuted blocks randomization does such a good job at controlling chronological bias that it has become the standard randomization procedure in clinical trials. But permuted blocks randomization is especially vulnerable to selection bias, so as a result, the maximum tolerated imbalance (MTI) procedures were proposed as better alternatives. In comparing the procedures, we have somewhat of a false controversy, in that actual practice goes uniformly one way (permuted blocks), whereas scientific arguments go uniformly the other way (MTI procedures). There is no argument in the literature to suggest that the permuted block design is better than or even as good as the MTI procedures, but this dearth is matched by an equivalent one regarding actual trials using the MTI procedures. So the 'controversy', if we are to call it that, pits misguided precedent against sound advice that tends to be ignored in practice. We shall review the issues to determine scientifically which of the procedures is better and, therefore, should be used. PMID:26337607

  7. Randomization in robot tasks

    NASA Technical Reports Server (NTRS)

    Erdmann, Michael

    1992-01-01

    This paper investigates the role of randomization in the solution of robot manipulation tasks. One example of randomization is shown by the strategy of shaking a bin holding a part in order to orient the part in a desired stable state with some high probability. Randomization can be useful for mobile robot navigation and as a means of guiding the design process.

  8. Random Item IRT Models

    ERIC Educational Resources Information Center

    De Boeck, Paul

    2008-01-01

    It is common practice in IRT to consider items as fixed and persons as random. Both, continuous and categorical person parameters are most often random variables, whereas for items only continuous parameters are used and they are commonly of the fixed type, although exceptions occur. It is shown in the present article that random item parameters…

  9. Quantum random number generation

    DOE PAGESBeta

    Ma, Xiongfeng; Yuan, Xiao; Cao, Zhu; Zhang, Zhen; Qi, Bing

    2016-06-28

    Here, quantum physics can be exploited to generate true random numbers, which play important roles in many applications, especially in cryptography. Genuine randomness from the measurement of a quantum system reveals the inherent nature of quantumness -- coherence, an important feature that differentiates quantum mechanics from classical physics. The generation of genuine randomness is generally considered impossible with only classical means. Based on the degree of trustworthiness on devices, quantum random number generators (QRNGs) can be grouped into three categories. The first category, practical QRNG, is built on fully trusted and calibrated devices and typically can generate randomness at amore » high speed by properly modeling the devices. The second category is self-testing QRNG, where verifiable randomness can be generated without trusting the actual implementation. The third category, semi-self-testing QRNG, is an intermediate category which provides a tradeoff between the trustworthiness on the device and the random number generation speed.« less

  10. Quantum random number generation

    SciTech Connect

    Ma, Xiongfeng; Yuan, Xiao; Cao, Zhu; Zhang, Zhen; Qi, Bing

    2016-01-01

    Here, quantum physics can be exploited to generate true random numbers, which play important roles in many applications, especially in cryptography. Genuine randomness from the measurement of a quantum system reveals the inherent nature of quantumness — coherence, an important feature that differentiates quantum mechanics from classical physics. The generation of genuine randomness is generally considered impossible with only classical means. Based on the degree of trustworthiness on devices, quantum random number generators (QRNGs) can be grouped into three categories. The first category, practical QRNG, is built on fully trusted and calibrated devices and typically can generate randomness at a high speed by properly modeling the devices. The second category is self-testing QRNG, where verifiable randomness can be generated without trusting the actual implementation. The third category, semi-self-testing QRNG, is an intermediate category which provides a tradeoff between the trustworthiness on the device and the random number generation speed.

  11. Blocked randomization with randomly selected block sizes.

    PubMed

    Efird, Jimmy

    2011-01-01

    When planning a randomized clinical trial, careful consideration must be given to how participants are selected for various arms of a study. Selection and accidental bias may occur when participants are not assigned to study groups with equal probability. A simple random allocation scheme is a process by which each participant has equal likelihood of being assigned to treatment versus referent groups. However, by chance an unequal number of individuals may be assigned to each arm of the study and thus decrease the power to detect statistically significant differences between groups. Block randomization is a commonly used technique in clinical trial design to reduce bias and achieve balance in the allocation of participants to treatment arms, especially when the sample size is small. This method increases the probability that each arm will contain an equal number of individuals by sequencing participant assignments by block. Yet still, the allocation process may be predictable, for example, when the investigator is not blind and the block size is fixed. This paper provides an overview of blocked randomization and illustrates how to avoid selection bias by using random block sizes. PMID:21318011

  12. Rest versus exercise as treatment for patients with low back pain and Modic changes. a randomized controlled clinical trial

    PubMed Central

    2012-01-01

    Background Clinical experience suggests that many patients with Modic changes have relatively severe and persistent low back pain (LBP), which typically appears to be resistant to treatment. Exercise therapy is the recommended treatment for chronic LBP, however, due to their underlying pathology, Modic changes might be a diagnostic subgroup that does not benefit from exercise. The objective of this study was to compare the current state-of-the art treatment approach (exercise and staying active) with a new approach (load reduction and daily rest) for people with Modic changes using a randomized controlled trial design. Methods Participants were patients from an outpatient clinic with persistent LBP and Modic changes. They were allocated using minimization to either rest therapy for 10 weeks with a recommendation to rest for two hours daily and the option of using a flexible lumbar belt or exercise therapy once a week for 10 weeks. Follow-up was at 10 weeks after recruitment and 52 weeks after intervention and the clinical outcome measures were pain, disability, general health and global assessment, supplemented by weekly information on low back problems and sick leave measured by short text message (SMS) tracking. Results In total, 100 patients were included in the study. Data on 87 patients at 10 weeks and 96 patients at one-year follow-up were available and were used in the intention-to-treat analysis. No statistically significant differences were found between the two intervention groups on any outcome. Conclusions No differences were found between the two treatment approaches, 'rest and reduced load' and 'exercise and staying active', in patients with persistent LBP and Modic changes. Trial Registration ClinicalTrials.gov: NCT00454792 PMID:22376791

  13. Acupoint Stimulation on Weight Reduction for Obesity: A Randomized Sham-Controlled Study.

    PubMed

    Yeh, Mei-Ling; Chu, Nain-Feng; Hsu, Man-Ying F; Hsu, Chin-Che; Chung, Yu-Chu

    2015-12-01

    Auricular acupoint stimulation has become a popular weight loss method. However, its efficacy for obesity treatment has not been fully studied. This study aimed to investigate the effect of a 10-week intervention of auricular electrical stimulation combined with auricular acupressure on weight reduction in obese outpatients. In this single-blind randomized sham-controlled study, 134 participants were randomly assigned to an experimental group receiving stimulation at true acupoints, or a sham group receiving stimulation delivered in the same manner but at sham acupoints. Each participant received nutrition counseling by a nutritionist weekly. The results showed significant differences in body mass index, blood pressure, total cholesterol, triglyceride, and leptin or adiponectin over time within the group, but not between the groups. This study could not exclude the effect of placebo and dietary consultation. Further study that adds a control group receiving no treatment is therefore needed to confirm the effects of auricular acupressure. PMID:25183702

  14. Clinical and histological effect of a low glycaemic load diet in treatment of acne vulgaris in Korean patients: a randomized, controlled trial.

    PubMed

    Kwon, Hyuck Hoon; Yoon, Ji Young; Hong, Jong Soo; Jung, Jae Yoon; Park, Mi Sun; Suh, Dae Hun

    2012-05-01

    Recent studies have suggested that dietary factors, specifically glycaemic load, may be involved in the pathogenesis of acne. The aim of this study was to determine the clinical and histological effects on acne lesions of a low glycaemic load diet. A total of 32 patients with mild to moderate acne were randomly assigned to either a low glycaemic load diet or a control group diet, and completed a 10-week, parallel dietary intervention trial. Results indicate successful lowering of the glycaemic load. Subjects within the low glycaemic group demonstrated significant clinical improvement in the number of both non-inflammatory and inflammatory acne lesions. Histopathological examination of skin samples revealed several characteristics, including reduced size of sebaceous glands, decreased inflammation, and reduced expression of sterol regulatory element-binding protein-1, and interleukin-8 in the low glycaemic load group. A reduction in glycaemic load of the diet for 10 weeks resulted in improvements in acne. PMID:22678562

  15. Reflecting Random Flights

    NASA Astrophysics Data System (ADS)

    De Gregorio, Alessandro; Orsingher, Enzo

    2015-09-01

    We consider random flights in reflecting on the surface of a sphere with center at the origin and with radius R, where reflection is performed by means of circular inversion. Random flights studied in this paper are motions where the orientation of the deviations are uniformly distributed on the unit-radius sphere . We obtain the explicit probability distributions of the position of the moving particle when the number of changes of direction is fixed and equal to . We show that these distributions involve functions which are solutions of the Euler-Poisson-Darboux equation. The unconditional probability distributions of the reflecting random flights are obtained by suitably randomizing n by means of a fractional-type Poisson process. Random flights reflecting on hyperplanes according to the optical reflection form are considered and the related distributional properties derived.

  16. Random pulse generator

    NASA Technical Reports Server (NTRS)

    Lindsey, R. S., Jr. (Inventor)

    1975-01-01

    An exemplary embodiment of the present invention provides a source of random width and random spaced rectangular voltage pulses whose mean or average frequency of operation is controllable within prescribed limits of about 10 hertz to 1 megahertz. A pair of thin-film metal resistors are used to provide a differential white noise voltage pulse source. Pulse shaping and amplification circuitry provide relatively short duration pulses of constant amplitude which are applied to anti-bounce logic circuitry to prevent ringing effects. The pulse outputs from the anti-bounce circuits are then used to control two one-shot multivibrators whose output comprises the random length and random spaced rectangular pulses. Means are provided for monitoring, calibrating and evaluating the relative randomness of the generator.

  17. Quantum random number generator

    DOEpatents

    Pooser, Raphael C.

    2016-05-10

    A quantum random number generator (QRNG) and a photon generator for a QRNG are provided. The photon generator may be operated in a spontaneous mode below a lasing threshold to emit photons. Photons emitted from the photon generator may have at least one random characteristic, which may be monitored by the QRNG to generate a random number. In one embodiment, the photon generator may include a photon emitter and an amplifier coupled to the photon emitter. The amplifier may enable the photon generator to be used in the QRNG without introducing significant bias in the random number and may enable multiplexing of multiple random numbers. The amplifier may also desensitize the photon generator to fluctuations in power supplied thereto while operating in the spontaneous mode. In one embodiment, the photon emitter and amplifier may be a tapered diode amplifier.

  18. Autonomous Byte Stream Randomizer

    NASA Technical Reports Server (NTRS)

    Paloulian, George K.; Woo, Simon S.; Chow, Edward T.

    2013-01-01

    Net-centric networking environments are often faced with limited resources and must utilize bandwidth as efficiently as possible. In networking environments that span wide areas, the data transmission has to be efficient without any redundant or exuberant metadata. The Autonomous Byte Stream Randomizer software provides an extra level of security on top of existing data encryption methods. Randomizing the data s byte stream adds an extra layer to existing data protection methods, thus making it harder for an attacker to decrypt protected data. Based on a generated crypto-graphically secure random seed, a random sequence of numbers is used to intelligently and efficiently swap the organization of bytes in data using the unbiased and memory-efficient in-place Fisher-Yates shuffle method. Swapping bytes and reorganizing the crucial structure of the byte data renders the data file unreadable and leaves the data in a deconstructed state. This deconstruction adds an extra level of security requiring the byte stream to be reconstructed with the random seed in order to be readable. Once the data byte stream has been randomized, the software enables the data to be distributed to N nodes in an environment. Each piece of the data in randomized and distributed form is a separate entity unreadable on its own right, but when combined with all N pieces, is able to be reconstructed back to one. Reconstruction requires possession of the key used for randomizing the bytes, leading to the generation of the same cryptographically secure random sequence of numbers used to randomize the data. This software is a cornerstone capability possessing the ability to generate the same cryptographically secure sequence on different machines and time intervals, thus allowing this software to be used more heavily in net-centric environments where data transfer bandwidth is limited.

  19. Randomness for Free

    NASA Astrophysics Data System (ADS)

    Chatterjee, Krishnendu; Doyen, Laurent; Gimbert, Hugo; Henzinger, Thomas A.

    We consider two-player zero-sum games on graphs. These games can be classified on the basis of the information of the players and on the mode of interaction between them. On the basis of information the classification is as follows: (a) partial-observation (both players have partial view of the game); (b) one-sided complete-observation (one player has complete observation); and (c) complete-observation (both players have complete view of the game). On the basis of mode of interaction we have the following classification: (a) concurrent (players interact simultaneously); and (b) turn-based (players interact in turn). The two sources of randomness in these games are randomness in transition function and randomness in strategies. In general, randomized strategies are more powerful than deterministic strategies, and randomness in transitions gives more general classes of games. We present a complete characterization for the classes of games where randomness is not helpful in: (a) the transition function (probabilistic transition can be simulated by deterministic transition); and (b) strategies (pure strategies are as powerful as randomized strategies). As consequence of our characterization we obtain new undecidability results for these games.

  20. Optofluidic random laser

    NASA Astrophysics Data System (ADS)

    Shivakiran Bhaktha, B. N.; Bachelard, Nicolas; Noblin, Xavier; Sebbah, Patrick

    2012-10-01

    Random lasing is reported in a dye-circulated structured polymeric microfluidic channel. The role of disorder, which results from limited accuracy of photolithographic process, is demonstrated by the variation of the emission spectrum with local-pump position and by the extreme sensitivity to a local perturbation of the structure. Thresholds comparable to those of conventional microfluidic lasers are achieved, without the hurdle of state-of-the-art cavity fabrication. Potential applications of optofluidic random lasers for on-chip sensors are discussed. Introduction of random lasers in the field of optofluidics is a promising alternative to on-chip laser integration with light and fluidic functionalities.

  1. Random array grid collimator

    DOEpatents

    Fenimore, E.E.

    1980-08-22

    A hexagonally shaped quasi-random no-two-holes touching grid collimator. The quasi-random array grid collimator eliminates contamination from small angle off-axis rays by using a no-two-holes-touching pattern which simultaneously provides for a self-supporting array increasng throughput by elimination of a substrate. The presentation invention also provides maximum throughput using hexagonally shaped holes in a hexagonal lattice pattern for diffraction limited applications. Mosaicking is also disclosed for reducing fabrication effort.

  2. Sleep Education Improves the Sleep Duration of Adolescents: A Randomized Controlled Pilot Study

    PubMed Central

    Kira, Geoff; Maddison, Ralph; Hull, Michelle; Blunden, Sarah; Olds, Timothy

    2014-01-01

    Purpose: To determine the feasibility and pilot a sleep education program in New Zealand high school students. Methods: A parallel, two-arm randomized controlled pilot trial was conducted. High school students (13 to 16 years) were randomly allocated to either a classroom-based sleep education program intervention (n = 15) or to a usual curriculum control group (n = 14). The sleep education program involved four 50-minute classroom-based education sessions with interactive groups. Students completed a 7-day sleep diary, a sleep questionnaire (including sleep hygiene, knowledge and problems) at baseline, post-intervention (4 weeks) and 10 weeks follow-up. Results: An overall treatment effect was observed for weekend sleep duration (F1,24 = 5.21, p = 0.03). Participants in the intervention group slept longer during weekend nights at 5 weeks (1:37 h:min, p = 0.01) and 10 weeks: (1:32 h:min, p = 0.03) compared to those in the control group. No differences were found between groups for sleep duration on weekday nights. No significant differences were observed between groups for any of the secondary outcomes (sleep hygiene, sleep problems, or sleep knowledge). Conclusions: A sleep education program appears to increase weekend sleep duration in the short term. Although this program was feasible, most schools are under time and resource pressure, thus alternative methods of delivery should be assessed for feasibility and efficacy. Larger trials of longer duration are needed to confirm these findings and determine the sustained effect of sleep education on sleep behavior and its impact on health and psychosocial outcomes. Commentary: A commentary on this article appears in this issue on page 793. Citation: Kira G, Maddison R, Hull M, Blunden S, Olds T. Sleep education improves the sleep duration of adolescents: a randomized controlled pilot study. J Clin Sleep Med 2014;10(7):787-792. PMID:25024657

  3. Random walks on networks

    NASA Astrophysics Data System (ADS)

    Donnelly, Isaac

    Random walks on lattices are a well used model for diffusion on continuum. They have been to model subdiffusive systems, systems with forcing and reactions as well as a combination of the three. We extend the traditional random walk framework to the network to obtain novel results. As an example due to the small graph diameter, the early time behaviour of subdiffusive dynamics dominates the observed system which has implications for models of the brain or airline networks. I would like to thank the Australian American Fulbright Association.

  4. Intermittency and random matrices

    NASA Astrophysics Data System (ADS)

    Sokoloff, Dmitry; Illarionov, E. A.

    2015-08-01

    A spectacular phenomenon of intermittency, i.e. a progressive growth of higher statistical moments of a physical field excited by an instability in a random medium, attracted the attention of Zeldovich in the last years of his life. At that time, the mathematical aspects underlying the physical description of this phenomenon were still under development and relations between various findings in the field remained obscure. Contemporary results from the theory of the product of independent random matrices (the Furstenberg theory) allowed the elaboration of the phenomenon of intermittency in a systematic way. We consider applications of the Furstenberg theory to some problems in cosmology and dynamo theory.

  5. On Random Numbers and Design

    ERIC Educational Resources Information Center

    Ben-Ari, Morechai

    2004-01-01

    The term "random" is frequently used in discussion of the theory of evolution, even though the mathematical concept of randomness is problematic and of little relevance in the theory. Therefore, since the core concept of the theory of evolution is the non-random process of natural selection, the term random should not be used in teaching the…

  6. A discrete fractional random transform

    NASA Astrophysics Data System (ADS)

    Liu, Zhengjun; Zhao, Haifa; Liu, Shutian

    2005-11-01

    We propose a discrete fractional random transform based on a generalization of the discrete fractional Fourier transform with an intrinsic randomness. Such discrete fractional random transform inheres excellent mathematical properties of the fractional Fourier transform along with some fantastic features of its own. As a primary application, the discrete fractional random transform has been used for image encryption and decryption.

  7. Uniform random number generators

    NASA Technical Reports Server (NTRS)

    Farr, W. R.

    1971-01-01

    Methods are presented for the generation of random numbers with uniform and normal distributions. Subprogram listings of Fortran generators for the Univac 1108, SDS 930, and CDC 3200 digital computers are also included. The generators are of the mixed multiplicative type, and the mathematical method employed is that of Marsaglia and Bray.

  8. Generating "Random" Integers

    ERIC Educational Resources Information Center

    Griffiths, Martin

    2011-01-01

    One of the author's undergraduate students recently asked him whether it was possible to generate a random positive integer. After some thought, the author realised that there were plenty of interesting mathematical ideas inherent in her question. So much so in fact, that the author decided to organise a workshop, open both to undergraduates and…

  9. Random lattice superstrings

    SciTech Connect

    Feng Haidong; Siegel, Warren

    2006-08-15

    We propose some new simplifying ingredients for Feynman diagrams that seem necessary for random lattice formulations of superstrings. In particular, half the fermionic variables appear only in particle loops (similarly to loop momenta), reducing the supersymmetry of the constituents of the type IIB superstring to N=1, as expected from their interpretation in the 1/N expansion as super Yang-Mills.

  10. Randomization and sampling issues

    USGS Publications Warehouse

    Geissler, P.H.

    1996-01-01

    The need for randomly selected routes and other sampling issues have been debated by the Amphibian electronic discussion group. Many excellent comments have been made, pro and con, but we have not reached consensus yet. This paper brings those comments together and attempts a synthesis. I hope that the resulting discussion will bring us closer to a consensus.

  11. Randomized Multicenter Feasibility Trial of Myofascial Physical Therapy for Treatment of Urologic Chronic Pelvic Pain Syndrome

    PubMed Central

    FitzGerald, Mary P; Anderson, Rodney U; Potts, Jeannette; Payne, Christopher K; Peters, Kenneth M; Clemens, J Quentin; Kotarinos, Rhonda; Fraser, Laura; Cosby, Annamarie; Fortman, Carole; Neville, Cynthia; Badillo, Suzanne; Odabachian, Lisa; Sanfield, Anna; O’Dougherty, Betsy; Halle-Podell, Rick; Cen, Liyi; Chuai, Shannon; Landis, J Richard; Kusek, John W; Nyberg, Leroy M

    2010-01-01

    Objectives To determine the feasibility of conducting a randomized clinical trial designed to compare two methods of manual therapy (myofascial physical therapy (MPT) and global therapeutic massage (GTM)) among patients with urologic chronic pelvic pain syndromes. Materials and Methods Our goal was to recruit 48 subjects with chronic prostatitis/chronic pelvic pain syndrome or interstitial cystitis/painful bladder syndrome at six clinical centers. Eligible patients were randomized to either MPT or GTM and were scheduled to receive up to 10 weekly treatments, each 1 hour in duration. Criteria to assess feasibility included adherence of therapists to prescribed therapeutic protocol as determined by records of treatment, adverse events which occurred during study treatment, and rate of response to therapy as assessed by the Patient Global Response Assessment (GRA). Primary outcome analysis compared response rates between treatment arms using Mantel-Haenszel methods. Results Twenty-three (49%) men and 24 (51%) women were randomized over a six month period. Twenty-four (51%) patients were randomized to GTM, 23 (49%) to MPT; 44 (94%) patients completed the study. Therapist adherence to the treatment protocols was excellent. The GRA response rate of 57% in the MPT group was significantly higher than the rate of 21% in the GTM treatment group (p=0.03). Conclusions The goals to judge feasibility of conducting a full-scale trial of physical therapy methods were met. The preliminary findings of a beneficial effect of MPT warrants further study. PMID:19535099

  12. Acemannan hydrogel dressing versus saline dressing for pressure ulcers. A randomized, controlled trial.

    PubMed

    Thomas, D R; Goode, P S; LaMaster, K; Tennyson, T

    1998-10-01

    Aloe vera has been used for centuries as a topical treatment for various conditions and as a cathartic. An amorphous hydrogel dressing derived from the aloe plant (Carrasyn Gel Wound Dressing, Carrington Laboratories, Inc., Irving, TX) is approved by the Food and Drug Administration for the management of Stages I through IV pressure ulcers. To evaluate effectiveness of this treatment, 30 patients were randomized to receive either daily topical application of the hydrogel study dressing (acemannan hydrogel wound dressing) or a moist saline gauze dressing. Complete healing of the study ulcer occurred in 19 of 30 subjects (63%) during the 10-week observation period. No difference was observed in complete healing between the experimental and the control groups (odds ratio 0.93, 95% CI 0.16, 5.2). This study indicates that the acemannan hydrogel dressing is as effective as, but is not superior to, a moist saline gauze wound dressing for the management of pressure ulcers. PMID:10326343

  13. Random very loose packings.

    PubMed

    Ciamarra, Massimo Pica; Coniglio, Antonio

    2008-09-19

    We measure the number Omega(phi) of mechanically stable states of volume fraction phi of a granular assembly under gravity. The granular entropy S(phi)=logOmega(phi) vanishes both at high density, at phi approximately equal to phi_rcp, and a low density, at phi approximately equal to phi_rvlp, where phi_rvlp is a new lower bound we call random very loose pack. phi_rlp is the volume fraction where the entropy is maximal. These findings allow for a clear explanation of compaction experiments and provide the first first-principle definition of the random loose volume fraction. In the context of the statistical mechanics approach to static granular materials, states with phi

  14. Relativistic Weierstrass random walks.

    PubMed

    Saa, Alberto; Venegeroles, Roberto

    2010-08-01

    The Weierstrass random walk is a paradigmatic Markov chain giving rise to a Lévy-type superdiffusive behavior. It is well known that special relativity prevents the arbitrarily high velocities necessary to establish a superdiffusive behavior in any process occurring in Minkowski spacetime, implying, in particular, that any relativistic Markov chain describing spacetime phenomena must be essentially Gaussian. Here, we introduce a simple relativistic extension of the Weierstrass random walk and show that there must exist a transition time t{c} delimiting two qualitative distinct dynamical regimes: the (nonrelativistic) superdiffusive Lévy flights, for tt{c} . Implications of this crossover between different diffusion regimes are discussed for some explicit examples. The study of such an explicit and simple Markov chain can shed some light on several results obtained in much more involved contexts. PMID:20866862

  15. Effect of Amitriptyline and Escitalopram on Functional Dyspepsia: a Multi-Center, Randomized, Controlled Study

    PubMed Central

    Talley, Nicholas J.; Locke, G. Richard; Saito, Yuri A.; Almazar, Ann E.; Bouras, Ernest P.; Howden, Colin W.; Lacy, Brian E.; DiBaise, John K.; Prather, Charlene M.; Abraham, Bincy P.; El-Serag, Hashem B.; Moayyedi, Paul; Herrick, Linda M.; Szarka, Lawrence A.; Camilleri, Michael; Hamilton, Frank A.; Schleck, Cathy D.; Tilkes, Katherine E.; Zinsmeister, Alan R.

    2015-01-01

    Background & Aims Anti-depressants are frequently prescribed to treat functional dyspepsia (FD), a common disorder characterized by upper abdominal symptoms, including discomfort or post-prandial fullness. However, there is little evidence for the efficacy of these drugs in patients with FD. We performed a randomized, double-blind, placebo-controlled trial to evaluate the effects of anti-depressant therapy effects on symptoms, gastric emptying (GE), and mealinduced satiety in patients with FD. Methods We performed a study at 8 North American sites of patients who met the Rome II criteria for FD and did not have depression or use anti-depressants. Subjects (n=292; 44±15 y old, 75% female, 70% with dysmotility-like FD, and 30% with ulcer-like FD) were randomly assigned to groups given placebo, 50 mg amitriptyline, or 10 mg escitalopram for 10 weeks. The primary endpoint was adequate relief of FD symptoms for ≥5 weeks of the last 10 weeks (out of 12). Secondary endpoints included GE time, maximum tolerated volume in a nutrient drink test, and FD-related quality of life. Results An adequate relief response was reported by 39 subjects given placebo (40%), 51 given amitriptyline (53%), and 37 given escitalopram (38%) (P=.05, following treatment, adjusted for baseline balancing factors including all subjects). Subjects with ulcer-like FD given amitriptyline were more than 3-fold more likely to report adequate relief than those given placebo (odds ratio=3.1; 95% confidence interval, 1.1–9.0). Neither amitriptyline nor escitalopram appeared to affect GE or meal-induced satiety after the 10 week period in any group. Subjects with delayed GE were less likely to report adequate relief than subjects with normal GE (odds ratio=0.4; 95% confidence interval, 0.2–0.8). Both anti-depressants improved overall quality-of-life. Conclusions Amitriptyline, but not escitalopram, appears to benefit some patients with FD— particularly those with ulcer-like (painful) FD. Patients

  16. The RANDOM computer program: A linear congruential random number generator

    NASA Technical Reports Server (NTRS)

    Miles, R. F., Jr.

    1986-01-01

    The RANDOM Computer Program is a FORTRAN program for generating random number sequences and testing linear congruential random number generators (LCGs). The linear congruential form of random number generator is discussed, and the selection of parameters of an LCG for a microcomputer described. This document describes the following: (1) The RANDOM Computer Program; (2) RANDOM.MOD, the computer code needed to implement an LCG in a FORTRAN program; and (3) The RANCYCLE and the ARITH Computer Programs that provide computational assistance in the selection of parameters for an LCG. The RANDOM, RANCYCLE, and ARITH Computer Programs are written in Microsoft FORTRAN for the IBM PC microcomputer and its compatibles. With only minor modifications, the RANDOM Computer Program and its LCG can be run on most micromputers or mainframe computers.

  17. A random number generator for continuous random variables

    NASA Technical Reports Server (NTRS)

    Guerra, V. M.; Tapia, R. A.; Thompson, J. R.

    1972-01-01

    A FORTRAN 4 routine is given which may be used to generate random observations of a continuous real valued random variable. Normal distribution of F(x), X, E(akimas), and E(linear) is presented in tabular form.

  18. Randomizing Roaches: Exploring the "Bugs" of Randomization in Experimental Design

    ERIC Educational Resources Information Center

    Wagler, Amy; Wagler, Ron

    2014-01-01

    Understanding the roles of random selection and random assignment in experimental design is a central learning objective in most introductory statistics courses. This article describes an activity, appropriate for a high school or introductory statistics course, designed to teach the concepts, values and pitfalls of random selection and assignment…

  19. Random numbers from vacuum fluctuations

    NASA Astrophysics Data System (ADS)

    Shi, Yicheng; Chng, Brenda; Kurtsiefer, Christian

    2016-07-01

    We implement a quantum random number generator based on a balanced homodyne measurement of vacuum fluctuations of the electromagnetic field. The digitized signal is directly processed with a fast randomness extraction scheme based on a linear feedback shift register. The random bit stream is continuously read in a computer at a rate of about 480 Mbit/s and passes an extended test suite for random numbers.

  20. Cluster Randomized Controlled Trial

    PubMed Central

    Young, John; Chapman, Katie; Nixon, Jane; Patel, Anita; Holloway, Ivana; Mellish, Kirste; Anwar, Shamaila; Breen, Rachel; Knapp, Martin; Murray, Jenni; Farrin, Amanda

    2015-01-01

    Background and Purpose— We developed a new postdischarge system of care comprising a structured assessment covering longer-term problems experienced by patients with stroke and their carers, linked to evidence-based treatment algorithms and reference guides (the longer-term stroke care system of care) to address the poor longer-term recovery experienced by many patients with stroke. Methods— A pragmatic, multicentre, cluster randomized controlled trial of this system of care. Eligible patients referred to community-based Stroke Care Coordinators were randomized to receive the new system of care or usual practice. The primary outcome was improved patient psychological well-being (General Health Questionnaire-12) at 6 months; secondary outcomes included functional outcomes for patients, carer outcomes, and cost-effectiveness. Follow-up was through self-completed postal questionnaires at 6 and 12 months. Results— Thirty-two stroke services were randomized (29 participated); 800 patients (399 control; 401 intervention) and 208 carers (100 control; 108 intervention) were recruited. In intention to treat analysis, the adjusted difference in patient General Health Questionnaire-12 mean scores at 6 months was −0.6 points (95% confidence interval, −1.8 to 0.7; P=0.394) indicating no evidence of statistically significant difference between the groups. Costs of Stroke Care Coordinator inputs, total health and social care costs, and quality-adjusted life year gains at 6 months, 12 months, and over the year were similar between the groups. Conclusions— This robust trial demonstrated no benefit in clinical or cost-effectiveness outcomes associated with the new system of care compared with usual Stroke Care Coordinator practice. Clinical Trial Registration— URL: http://www.controlled-trials.com. Unique identifier: ISRCTN 67932305. PMID:26152298

  1. Random recursive trees and the elephant random walk

    NASA Astrophysics Data System (ADS)

    Kürsten, Rüdiger

    2016-03-01

    One class of random walks with infinite memory, so-called elephant random walks, are simple models describing anomalous diffusion. We present a surprising connection between these models and bond percolation on random recursive trees. We use a coupling between the two models to translate results from elephant random walks to the percolation process. We calculate, besides other quantities, exact expressions for the first and the second moment of the root cluster size and of the number of nodes in child clusters of the first generation. We further introduce another model, the skew elephant random walk, and calculate the first and second moment of this process.

  2. Randomly Hyperbranched Polymers

    NASA Astrophysics Data System (ADS)

    Konkolewicz, Dominik; Gilbert, Robert G.; Gray-Weale, Angus

    2007-06-01

    We describe a model for the structures of randomly hyperbranched polymers in solution, and find a logarithmic growth of radius with polymer mass. We include segmental overcrowding, which puts an upper limit on the density. The model is tested against simulations, against data on amylopectin, a major component of starch, on glycogen, and on polyglycerols. For samples of synthetic polyglycerol and glycogen, our model holds well for all the available data. The model reveals higher-level scaling structure in glycogen, related to the β particles seen in electron microscopy.

  3. Coloring random graphs.

    PubMed

    Mulet, R; Pagnani, A; Weigt, M; Zecchina, R

    2002-12-23

    We study the graph coloring problem over random graphs of finite average connectivity c. Given a number q of available colors, we find that graphs with low connectivity admit almost always a proper coloring, whereas graphs with high connectivity are uncolorable. Depending on q, we find the precise value of the critical average connectivity c(q). Moreover, we show that below c(q) there exists a clustering phase c in [c(d),c(q)] in which ground states spontaneously divide into an exponential number of clusters and where the proliferation of metastable states is responsible for the onset of complexity in local search algorithms. PMID:12484862

  4. Can randomization be informative?

    NASA Astrophysics Data System (ADS)

    Pereira, Carlos A. B.; Campos, Thiago F.; Silva, Gustavo M.; Wechsler, Sergio

    2012-10-01

    In this paper the Pair of Siblings Paradox introduced by Pereira [1] is extended by considering more than two children and more than one child observed for gender. We follow the same lines of Wechsler et al. [2] that generalizes the three prisoners' dilemma, introduced by Gardner [3]. This paper's conjecture is that the Pair of Siblings and the Three Prisoners dilemma are dual paradoxes. Looking at possible likelihoods, the sure (randomized) selection for the former is non informative (informative), the opposite that holds for the latter. This situation is maintained for generalizations. Non informative likelihood here means that prior and posterior are equal.

  5. Investigating the Randomness of Numbers

    ERIC Educational Resources Information Center

    Pendleton, Kenn L.

    2009-01-01

    The use of random numbers is pervasive in today's world. Random numbers have practical applications in such far-flung arenas as computer simulations, cryptography, gambling, the legal system, statistical sampling, and even the war on terrorism. Evaluating the randomness of extremely large samples is a complex, intricate process. However, the…

  6. Random Numbers and Quantum Computers

    ERIC Educational Resources Information Center

    McCartney, Mark; Glass, David

    2002-01-01

    The topic of random numbers is investigated in such a way as to illustrate links between mathematics, physics and computer science. First, the generation of random numbers by a classical computer using the linear congruential generator and logistic map is considered. It is noted that these procedures yield only pseudo-random numbers since…

  7. Randomized Response Analysis in Mplus

    ERIC Educational Resources Information Center

    Hox, Joop; Lensvelt-Mulders, Gerty

    2004-01-01

    This article describes a technique to analyze randomized response data using available structural equation modeling (SEM) software. The randomized response technique was developed to obtain estimates that are more valid when studying sensitive topics. The basic feature of all randomized response methods is that the data are deliberately…

  8. Random Selection for Drug Screening

    SciTech Connect

    Center for Human Reliability Studies

    2007-05-01

    Simple random sampling is generally the starting point for a random sampling process. This sampling technique ensures that each individual within a group (population) has an equal chance of being selected. There are a variety of ways to implement random sampling in a practical situation.

  9. Random-walk enzymes

    NASA Astrophysics Data System (ADS)

    Mak, Chi H.; Pham, Phuong; Afif, Samir A.; Goodman, Myron F.

    2015-09-01

    Enzymes that rely on random walk to search for substrate targets in a heterogeneously dispersed medium can leave behind complex spatial profiles of their catalyzed conversions. The catalytic signatures of these random-walk enzymes are the result of two coupled stochastic processes: scanning and catalysis. Here we develop analytical models to understand the conversion profiles produced by these enzymes, comparing an intrusive model, in which scanning and catalysis are tightly coupled, against a loosely coupled passive model. Diagrammatic theory and path-integral solutions of these models revealed clearly distinct predictions. Comparison to experimental data from catalyzed deaminations deposited on single-stranded DNA by the enzyme activation-induced deoxycytidine deaminase (AID) demonstrates that catalysis and diffusion are strongly intertwined, where the chemical conversions give rise to new stochastic trajectories that were absent if the substrate DNA was homogeneous. The C →U deamination profiles in both analytical predictions and experiments exhibit a strong contextual dependence, where the conversion rate of each target site is strongly contingent on the identities of other surrounding targets, with the intrusive model showing an excellent fit to the data. These methods can be applied to deduce sequence-dependent catalytic signatures of other DNA modification enzymes, with potential applications to cancer, gene regulation, and epigenetics.

  10. Randomness in Competitions

    NASA Astrophysics Data System (ADS)

    Ben-Naim, E.; Hengartner, N. W.; Redner, S.; Vazquez, F.

    2013-05-01

    We study the effects of randomness on competitions based on an elementary random process in which there is a finite probability that a weaker team upsets a stronger team. We apply this model to sports leagues and sports tournaments, and compare the theoretical results with empirical data. Our model shows that single-elimination tournaments are efficient but unfair: the number of games is proportional to the number of teams N, but the probability that the weakest team wins decays only algebraically with N. In contrast, leagues, where every team plays every other team, are fair but inefficient: the top √{N} of teams remain in contention for the championship, while the probability that the weakest team becomes champion is exponentially small. We also propose a gradual elimination schedule that consists of a preliminary round and a championship round. Initially, teams play a small number of preliminary games, and subsequently, a few teams qualify for the championship round. This algorithm is fair and efficient: the best team wins with a high probability and the number of games scales as N 9/5, whereas traditional leagues require N 3 games to fairly determine a champion.

  11. Random rough surface photofabrication

    NASA Astrophysics Data System (ADS)

    Brissonneau, Vincent; Escoubas, Ludovic; Flory, François; Berginc, Gérard

    2011-10-01

    Random rough surfaces are of primary interest for their optical properties: reducing reflection at the interface or obtaining specific scattering diagram for example. Thus controlling surface statistics during the fabrication process paves the way to original and specific behaviors of reflected optical waves. We detail an experimental method allowing the fabrication of random rough surfaces showing tuned statistical properties. A two-step photoresist exposure process was developed. In order to initiate photoresist polymerization, an energy threshold needs to be reached by light exposure. This energy is brought by a uniform exposure equipment comprising UV-LEDs. This pre-exposure is studied by varying parameters such as optical power and exposure time. The second step consists in an exposure based on the Gray method.1 The speckle pattern of an enlarged scattered laser beam is used to insolate the photoresist. A specific photofabrication bench using an argon ion laser was implemented. Parameters such as exposure time and distances between optical components are discussed. Then, we describe how we modify the speckle-based exposure bench to include a spatial light modulator (SLM). The SLM used is a micromirror matrix known as Digital Micromirror Device (DMD) which allows spatial modulation by displaying binary images. Thus, the spatial beam shape can be tuned and so the speckle pattern on the photoresist is modified. As the photoresist photofabricated surface is correlated to the speckle pattern used to insolate, the roughness parameters can be adjusted.

  12. Random-walk enzymes

    PubMed Central

    Mak, Chi H.; Pham, Phuong; Afif, Samir A.; Goodman, Myron F.

    2015-01-01

    Enzymes that rely on random walk to search for substrate targets in a heterogeneously dispersed medium can leave behind complex spatial profiles of their catalyzed conversions. The catalytic signatures of these random-walk enzymes are the result of two coupled stochastic processes: scanning and catalysis. Here we develop analytical models to understand the conversion profiles produced by these enzymes, comparing an intrusive model, in which scanning and catalysis are tightly coupled, against a loosely coupled passive model. Diagrammatic theory and path-integral solutions of these models revealed clearly distinct predictions. Comparison to experimental data from catalyzed deaminations deposited on single-stranded DNA by the enzyme activation-induced deoxycytidine deaminase (AID) demonstrates that catalysis and diffusion are strongly intertwined, where the chemical conversions give rise to new stochastic trajectories that were absent if the substrate DNA was homogeneous. The C → U deamination profiles in both analytical predictions and experiments exhibit a strong contextual dependence, where the conversion rate of each target site is strongly contingent on the identities of other surrounding targets, with the intrusive model showing an excellent fit to the data. These methods can be applied to deduce sequence-dependent catalytic signatures of other DNA modification enzymes, with potential applications to cancer, gene regulation, and epigenetics. PMID:26465508

  13. Atomoxetine for Orthostatic Hypotension in an Elderly Patient Over 10 Weeks: A Case Report.

    PubMed

    Hale, Genevieve M; Brenner, Michael

    2015-09-01

    Several nonpharmacologic strategies for orthostatic hypotension exist including avoiding large carbohydrate-rich meals; limiting alcohol consumption; maintaining adequate hydration; adding salt to foods; and using compression stockings, tilt-table exercises, or abdominal binders. If these fail, however, only limited evidence-based pharmacologic treatment options are available including the use of fludrocortisone, midodrine, pyridostigmine, and droxidopa as well as pseudoephedrine, ocetreotide, and atomoxetine. This report discusses a case of atomoxetine use for 10 weeks in an elderly patient with primary orthostatic hypotension. An 84-year-old man with long-standing primary orthostatic hypotension presented to our ambulatory cardiology pharmacotherapy clinic after several unsuccessful pharmacologic therapies including fludrocortisone, midodrine, and pyridostigmine. Nonpharmacologic strategies were also implemented. Atomoxetine was initiated, and the patient showed gradual improvements in symptoms and blood pressure control over the course of 10 weeks. Our data suggest that low-dose atomoxetine is an effective and safe agent for symptom improvement and blood pressure control in elderly patients with primary orthostatic hypotension. PMID:26406777

  14. HP-PRRSV challenge of 4 and 10-week-old pigs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In 2006 a unique syndrome was recognized in growing pigs in China with the predominant clinical signs being high fever, anorexia, listlessness, red discoloration of skin, and respiratory distress. The disease had a very high morbidity and mortality rate and became known as porcine high fever disease...

  15. The Impact of Peer Support and mp3 Messaging on Adherence to Inhaled Corticosteroids in Minority Adolescents with Asthma: A Randomized Controlled Trial

    PubMed Central

    Mosnaim, Giselle; Li, Hong; Martin, Molly; Richardson, DeJuran; Belice, Paula Jo; Avery, Elizabeth; Ryan, Norman; Bender, Bruce; Powell, Lynda

    2013-01-01

    Background Poor adherence to inhaled corticosteroids (ICS) is a critical risk factor contributing to asthma morbidity among low-income minority adolescents. Objective This trial tested whether peer support group meetings and peer asthma messages delivered via mp3 players improved adherence to ICS. Methods Low-income African American and/or Hispanic adolescents, ages 11–16, with persistent asthma, and poor (≤ 48%) adherence to prescription ICS during the 3-week run-in were randomized to intervention or attention control groups (ATG) for the 10-week treatment. During treatment, the intervention arm participated in weekly coping peer group support sessions and received mp3 peer-recorded asthma messages promoting adherence. The ATG participated in weekly meetings with a research assistant and received an equivalent number of mp3 doctor-recorded asthma messages. Adherence was measured using self-report and the DoserCT, (Meditrac, Inc.), an electronic dose counter. The primary outcome was the difference in adherence at 10 weeks between the two arms. Results Thirty-four subjects were randomized to each arm. At 10 weeks, no statistical difference in objectively measured adherence could be detected between the two arms adjusting for baseline adherence (P = 0.929). Adherence declined in both groups over the course of the active treatment period. Participants’ in both study arms self-reported adherence was significantly higher than their objectively measured adherence at week 10 (P < 0.0001). Conclusion Improving medication adherence in longitudinal studies is challenging. Peer support and mp3-delivered peer asthma messages may not be of sufficient dose to improve outcomes. PMID:24565620

  16. Mapping in random-structures

    SciTech Connect

    Reidys, C.M.

    1996-06-01

    A mapping in random-structures is defined on the vertices of a generalized hypercube Q{sub {alpha}}{sup n}. A random-structure will consist of (1) a random contact graph and (2) a family of relations imposed on adjacent vertices. The vertex set of a random contact graph will be the set of all coordinates of a vertex P {element_of} Q{sub {alpha}}{sup n}. Its edge will be the union of the edge sets of two random graphs. The first is a random 1-regular graph on 2m vertices (coordinates) and the second is a random graph G{sub p} with p = c{sub 2}/n on all n vertices (coordinates). The structure of the random contact graphs will be investigated and it will be shown that for certain values of m, c{sub 2} the mapping in random-structures allows to search by the set of random-structures. This is applied to mappings in RNA-secondary structures. Also, the results on random-structures might be helpful for designing 3D-folding algorithms for RNA.

  17. Accelerated randomized benchmarking

    NASA Astrophysics Data System (ADS)

    Granade, Christopher; Ferrie, Christopher; Cory, D. G.

    2015-01-01

    Quantum information processing offers promising advances for a wide range of fields and applications, provided that we can efficiently assess the performance of the control applied in candidate systems. That is, we must be able to determine whether we have implemented a desired gate, and refine accordingly. Randomized benchmarking reduces the difficulty of this task by exploiting symmetries in quantum operations. Here, we bound the resources required for benchmarking and show that, with prior information, we can achieve several orders of magnitude better accuracy than in traditional approaches to benchmarking. Moreover, by building on state-of-the-art classical algorithms, we reach these accuracies with near-optimal resources. Our approach requires an order of magnitude less data to achieve the same accuracies and to provide online estimates of the errors in the reported fidelities. We also show that our approach is useful for physical devices by comparing to simulations.

  18. Structure of random foam.

    SciTech Connect

    Reinelt, Douglas A.; van Swol, Frank B.; Kraynik, Andrew Michael

    2004-06-01

    The Surface Evolver was used to compute the equilibrium microstructure of dry soap foams with random structure and a wide range of cell-size distributions. Topological and geometric properties of foams and individual cells were evaluated. The theory for isotropic Plateau polyhedra describes the dependence of cell geometric properties on their volume and number of faces. The surface area of all cells is about 10% greater than a sphere of equal volume; this leads to a simple but accurate theory for the surface free energy density of foam. A novel parameter based on the surface-volume mean bubble radius R32 is used to characterize foam polydispersity. The foam energy, total cell edge length, and average number of faces per cell all decrease with increasing polydispersity. Pentagonal faces are the most common in monodisperse foam but quadrilaterals take over in highly polydisperse structures.

  19. How random are random numbers generated using photons?

    NASA Astrophysics Data System (ADS)

    Solis, Aldo; Angulo Martínez, Alí M.; Ramírez Alarcón, Roberto; Cruz Ramírez, Hector; U'Ren, Alfred B.; Hirsch, Jorge G.

    2015-06-01

    Randomness is fundamental in quantum theory, with many philosophical and practical implications. In this paper we discuss the concept of algorithmic randomness, which provides a quantitative method to assess the Borel normality of a given sequence of numbers, a necessary condition for it to be considered random. We use Borel normality as a tool to investigate the randomness of ten sequences of bits generated from the differences between detection times of photon pairs generated by spontaneous parametric downconversion. These sequences are shown to fulfil the randomness criteria without difficulties. As deviations from Borel normality for photon-generated random number sequences have been reported in previous work, a strategy to understand these diverging findings is outlined.

  20. Effectiveness of low-dose doxycycline (LDD) on clinical symptoms of Sjögren's Syndrome: a randomized, double-blind, placebo controlled cross-over study

    PubMed Central

    Seitsalo, Hubertus; Niemelä, Raija K; Marinescu-Gava, Magdalena; Vuotila, Tuija; Tjäderhane, Leo; Salo, Tuula

    2007-01-01

    Background Matrix metalloproteinases (MMPs) are proteolytic enzymes that may contribute to tissue destruction in Sjögren's syndrome (SS). Low-dose doxycycline (LDD) inhibits MMPs. We evaluated the efficacy of LDD for the subjective symptoms in primary SS patients. This was a randomized, double blind, placebo controlled cross-over study. 22 patients were randomly assigned to receive either 20 mg LDD or matching placebo twice a day for 10 weeks. The first medication period was followed by 10-week washout period, after which the patient received either LDD or placebo, depending on the first drug received, followed by the second washout period. Stimulated saliva flow rates and pH were measured before and after one and ten weeks of each medication and after washout periods. VAS scale was used to assess the effect of LDD and placebo on following six subjective symptoms: xerostomia; xerophtalmia; difficulty of swallowing; myalgia; arthralgia; and fatigue. The effect was evaluated for each medication and washout period separately. Results Overall, the effects of medications on subjective symptoms were minor. Wilcoxon test demonstrated increased fatigue with LDD during medication (p < 0.05). The differences may, however, reflect normal fluctuation of symptoms in SS patients. Conclusion LDD may not be useful in reducing the primary SS symptoms. PMID:18163919

  1. Does Random Dispersion Help Survival?

    NASA Astrophysics Data System (ADS)

    Schinazi, Rinaldo B.

    2015-04-01

    Many species live in colonies that prosper for a while and then collapse. After the collapse the colony survivors disperse randomly and found new colonies that may or may not make it depending on the new environment they find. We use birth and death chains in random environments to model such a population and to argue that random dispersion is a superior strategy for survival.

  2. A Random Variable Transformation Process.

    ERIC Educational Resources Information Center

    Scheuermann, Larry

    1989-01-01

    Provides a short BASIC program, RANVAR, which generates random variates for various theoretical probability distributions. The seven variates include: uniform, exponential, normal, binomial, Poisson, Pascal, and triangular. (MVL)

  3. Diffusion in random networks

    NASA Astrophysics Data System (ADS)

    Padrino, Juan C.; Zhang, Duan Z.

    2015-11-01

    The ensemble phase averaging technique is applied to model mass transport in a porous medium. The porous material is idealized as an ensemble of random networks, where each network consists of a set of junction points representing the pores and tortuous channels connecting them. Inside a channel, fluid transport is assumed to be governed by the one-dimensional diffusion equation. Mass balance leads to an integro-differential equation for the pores mass density. Instead of attempting to solve this equation, and equivalent set of partial differential equations is derived whose solution is sought numerically. As a test problem, we consider the one-dimensional diffusion of a substance from one end to the other in a bounded domain. For a statistically homogeneous and isotropic material, results show that for relatively large times the pore mass density evolution from the new theory is significantly delayed in comparison with the solution from the classical diffusion equation. In the short-time case, when the solution evolves with time as if the domain were semi-infinite, numerical results indicate that the pore mass density becomes a function of the similarity variable xt- 1 / 4 rather than xt- 1 / 2 characteristic of classical diffusion. This result was verified analytically. Possible applications of this framework include flow in gas shales. Work supported by LDRD project of LANL.

  4. Nonvolatile random access memory

    NASA Technical Reports Server (NTRS)

    Wu, Jiin-Chuan (Inventor); Stadler, Henry L. (Inventor); Katti, Romney R. (Inventor)

    1994-01-01

    A nonvolatile magnetic random access memory can be achieved by an array of magnet-Hall effect (M-H) elements. The storage function is realized with a rectangular thin-film ferromagnetic material having an in-plane, uniaxial anisotropy and inplane bipolar remanent magnetization states. The thin-film magnetic element is magnetized by a local applied field, whose direction is used to form either a 0 or 1 state. The element remains in the 0 or 1 state until a switching field is applied to change its state. The stored information is detcted by a Hall-effect sensor which senses the fringing field from the magnetic storage element. The circuit design for addressing each cell includes transistor switches for providing a current of selected polarity to store a binary digit through a separate conductor overlying the magnetic element of the cell. To read out a stored binary digit, transistor switches are employed to provide a current through a row of Hall-effect sensors connected in series and enabling a differential voltage amplifier connected to all Hall-effect sensors of a column in series. To avoid read-out voltage errors due to shunt currents through resistive loads of the Hall-effect sensors of other cells in the same column, at least one transistor switch is provided between every pair of adjacent cells in every row which are not turned on except in the row of the selected cell.

  5. Randomized parcellation based inference.

    PubMed

    Da Mota, Benoit; Fritsch, Virgile; Varoquaux, Gaël; Banaschewski, Tobias; Barker, Gareth J; Bokde, Arun L W; Bromberg, Uli; Conrod, Patricia; Gallinat, Jürgen; Garavan, Hugh; Martinot, Jean-Luc; Nees, Frauke; Paus, Tomas; Pausova, Zdenka; Rietschel, Marcella; Smolka, Michael N; Ströhle, Andreas; Frouin, Vincent; Poline, Jean-Baptiste; Thirion, Bertrand

    2014-04-01

    Neuroimaging group analyses are used to relate inter-subject signal differences observed in brain imaging with behavioral or genetic variables and to assess risks factors of brain diseases. The lack of stability and of sensitivity of current voxel-based analysis schemes may however lead to non-reproducible results. We introduce a new approach to overcome the limitations of standard methods, in which active voxels are detected according to a consensus on several random parcellations of the brain images, while a permutation test controls the false positive risk. Both on synthetic and real data, this approach shows higher sensitivity, better accuracy and higher reproducibility than state-of-the-art methods. In a neuroimaging-genetic application, we find that it succeeds in detecting a significant association between a genetic variant next to the COMT gene and the BOLD signal in the left thalamus for a functional Magnetic Resonance Imaging contrast associated with incorrect responses of the subjects from a Stop Signal Task protocol. PMID:24262376

  6. Ferroelectric random access memories.

    PubMed

    Ishiwara, Hiroshi

    2012-10-01

    Ferroelectric random access memory (FeRAM) is a nonvolatile memory, in which data are stored using hysteretic P-E (polarization vs. electric field) characteristics in a ferroelectric film. In this review, history and characteristics of FeRAMs are first introduced. It is described that there are two types of FeRAMs, capacitor-type and FET-type, and that only the capacitor-type FeRAM is now commercially available. In chapter 2, properties of ferroelectric films are discussed from a viewpoint of FeRAM application, in which particular attention is paid to those of Pb(Zr,Ti)O3, SrBi2Ta2O9, and BiFeO3. Then, cell structures and operation principle of the capacitor-type FeRAMs are discussed in chapter 3. It is described that the stacked technology of ferroelectric capacitors and development of new materials with large remanent polarization are important for fabricating high-density memories. Finally, in chapter 4, the optimized gate structure in ferroelectric-gate field-effect transistors is discussed and experimental results showing excellent data retention characteristics are presented. PMID:23421123

  7. Phase transitions on random lattices: how random is topological disorder?

    PubMed

    Barghathi, Hatem; Vojta, Thomas

    2014-09-19

    We study the effects of topological (connectivity) disorder on phase transitions. We identify a broad class of random lattices whose disorder fluctuations decay much faster with increasing length scale than those of generic random systems, yielding a wandering exponent of ω=(d-1)/(2d) in d dimensions. The stability of clean critical points is thus governed by the criterion (d+1)ν>2 rather than the usual Harris criterion dν>2, making topological disorder less relevant than generic randomness. The Imry-Ma criterion is also modified, allowing first-order transitions to survive in all dimensions d>1. These results explain a host of puzzling violations of the original criteria for equilibrium and nonequilibrium phase transitions on random lattices. We discuss applications, and we illustrate our theory by computer simulations of random Voronoi and other lattices. PMID:25279615

  8. Random distributed feedback fibre lasers

    NASA Astrophysics Data System (ADS)

    Turitsyn, Sergei K.; Babin, Sergey A.; Churkin, Dmitry V.; Vatnik, Ilya D.; Nikulin, Maxim; Podivilov, Evgenii V.

    2014-09-01

    The concept of random lasers exploiting multiple scattering of photons in an amplifying disordered medium in order to generate coherent light without a traditional laser resonator has attracted a great deal of attention in recent years. This research area lies at the interface of the fundamental theory of disordered systems and laser science. The idea was originally proposed in the context of astrophysics in the 1960s by V.S. Letokhov, who studied scattering with “negative absorption” of the interstellar molecular clouds. Research on random lasers has since developed into a mature experimental and theoretical field. A simple design of such lasers would be promising for potential applications. However, in traditional random lasers the properties of the output radiation are typically characterized by complex features in the spatial, spectral and time domains, making them less attractive than standard laser systems in terms of practical applications. Recently, an interesting and novel type of one-dimensional random laser that operates in a conventional telecommunication fibre without any pre-designed resonator mirrors-random distributed feedback fibre laser-was demonstrated. The positive feedback required for laser generation in random fibre lasers is provided by the Rayleigh scattering from the inhomogeneities of the refractive index that are naturally present in silica glass. In the proposed laser concept, the randomly backscattered light is amplified through the Raman effect, providing distributed gain over distances up to 100 km. Although an effective reflection due to the Rayleigh scattering is extremely small (˜0.1%), the lasing threshold may be exceeded when a sufficiently large distributed Raman gain is provided. Such a random distributed feedback fibre laser has a number of interesting and attractive features. The fibre waveguide geometry provides transverse confinement, and effectively one-dimensional random distributed feedback leads to the generation

  9. Students' Misconceptions about Random Variables

    ERIC Educational Resources Information Center

    Kachapova, Farida; Kachapov, Ilias

    2012-01-01

    This article describes some misconceptions about random variables and related counter-examples, and makes suggestions about teaching initial topics on random variables in general form instead of doing it separately for discrete and continuous cases. The focus is on post-calculus probability courses. (Contains 2 figures.)

  10. Ticks of a Random clock

    NASA Astrophysics Data System (ADS)

    Jung, P.; Talkner, P.

    2010-09-01

    A simple way to convert a purely random sequence of events into a signal with a strong periodic component is proposed. The signal consists of those instants of time at which the length of the random sequence exceeds an integer multiple of a given number. The larger this number the more pronounced the periodic behavior becomes.

  11. Computer generation of random deviates.

    PubMed

    Cormack, J; Shuter, B

    1991-06-01

    The need for random deviates arises in many scientific applications, such as the simulation of physical processes, numerical evaluation of complex mathematical formulae and the modeling of decision processes. In medical physics, Monte Carlo simulations have been used in radiology, radiation therapy and nuclear medicine. Specific instances include the modelling of x-ray scattering processes and the addition of random noise to images or curves in order to assess the effects of various processing procedures. Reliable sources of random deviates with statistical properties indistinguishable from true random deviates are a fundamental necessity for such tasks. This paper provides a review of computer algorithms which can be used to generate uniform random deviates and other distributions of interest to medical physicists, along with a few caveats relating to various problems and pitfalls which can occur. Source code listings for the generators discussed (in FORTRAN, Turbo-PASCAL and Data General ASSEMBLER) are available on request from the authors. PMID:1747086

  12. Randomness versus nonlocality and entanglement.

    PubMed

    Acín, Antonio; Massar, Serge; Pironio, Stefano

    2012-03-01

    The outcomes obtained in Bell tests involving two-outcome measurements on two subsystems can, in principle, generate up to 2 bits of randomness. However, the maximal violation of the Clauser-Horne-Shimony-Holt inequality guarantees the generation of only 1.23 bits of randomness. We prove here that quantum correlations with arbitrarily little nonlocality and states with arbitrarily little entanglement can be used to certify that close to the maximum of 2 bits of randomness are produced. Our results show that nonlocality, entanglement, and randomness are inequivalent quantities. They also imply that device-independent quantum key distribution with an optimal key generation rate is possible by using almost-local correlations and that device-independent randomness generation with an optimal rate is possible with almost-local correlations and with almost-unentangled states. PMID:22463395

  13. Dynamic response of random parametered structures with random excitation. [DYNAMO

    SciTech Connect

    Branstetter, L.J.; Paez, T.L.

    1986-02-01

    A Taylor series expansion technique is used for numerical evaluation of the statistical response moments of a linear multidegree of freedom (MDF) system having random stiffness characteristics, when excited by either stationary or nonstationary random load components. Equations are developed for the cases of white noise loading and single step memory loading, and a method is presented to extend the solution to multistep memory loading. The equations are greatly simplified by the assumption that all random quantities are normally distributed. A computer program is developed to calculate the response moments of example systems. A program user's manual and listing (DYNAMO) are included. Future extensions of the work and potential applications are discussed.

  14. Topiramate for the management of methamphetamine dependence: a pilot randomized, double-blind, placebo-controlled trial.

    PubMed

    Rezaei, Farzin; Ghaderi, Ebrahim; Mardani, Roya; Hamidi, Seiran; Hassanzadeh, Kambiz

    2016-06-01

    To date, no medication has been approved as an effective treatment for methamphetamine dependence. Topiramate has attracted considerable attention as a treatment for the dependence on alcohol and stimulants. Therefore, this study aimed to evaluate the effect of topiramate for methamphetamine dependence. This study was a double-blind, randomized, placebo-controlled trial. In the present investigation, 62 methamphetamine-dependent adults were enrolled and randomized into two groups, and received topiramate or a placebo for 10 weeks in escalating doses from 50 mg/day to the target maintenance dose of 200 mg/day. Addiction severity index (ASI) and craving scores were registered every week. The Beck questionnaire was also given to each participant at baseline and every 2 weeks during the treatment. Urine samples were collected at baseline and every 2 weeks during the treatment. Fifty-seven patients completed 10 weeks of the trial. There was no significant difference between both groups in the mean percentage of prescribed capsules taken by the participants. At week six, the topiramate group showed a significantly lower proportion of methamphetamine-positive urine tests in comparison with the placebo group (P = 0.01). In addition, there were significantly lower scores in the topiramate group in comparison with the placebo group in two domains of ASI: drug use severity (P < 0.001) and drug need (P < 0.001). Furthermore, the craving score (duration) significantly declined in the topiramate patients compared to those receiving the placebo. In conclusion, the results of this trial suggest that topiramate may be beneficial for the treatment of methamphetamine dependence. PMID:26751259

  15. Mental skills training with basic combat training soldiers: A group-randomized trial.

    PubMed

    Adler, Amy B; Bliese, Paul D; Pickering, Michael A; Hammermeister, Jon; Williams, Jason; Harada, Coreen; Csoka, Louis; Holliday, Bernie; Ohlson, Carl

    2015-11-01

    Cognitive skills training has been linked to greater skills, self-efficacy, and performance. Although research in a variety of organizational settings has demonstrated training efficacy, few studies have assessed cognitive skills training using rigorous, longitudinal, randomized trials with active controls. The present study examined cognitive skills training in a high-risk occupation by randomizing 48 platoons (N = 2,432 soldiers) in basic combat training to either (a) mental skills training or (b) an active comparison condition (military history). Surveys were conducted at baseline and 3 times across the 10-week course. Multilevel mixed-effects models revealed that soldiers in the mental skills training condition reported greater use of a range of cognitive skills and increased confidence relative to those in the control condition. Soldiers in the mental skills training condition also performed better on obstacle course events, rappelling, physical fitness, and initial weapons qualification scores, although effects were generally moderated by gender and previous experience. Overall, effects were small; however, given the rigor of the design, the findings clearly contribute to the broader literature by providing supporting evidence that cognitive training skills can enhance performance in occupational and sports settings. Future research should address gender and experience to determine the need for targeting such training appropriately. PMID:26011718

  16. BE-ACTIV for Depression in Nursing Homes: Primary Outcomes of a Randomized Clinical Trial

    PubMed Central

    Van Haitsma, Kimberly; Schoenbachler, Ben; Looney, Stephen W.

    2015-01-01

    Objectives. To report the primary outcomes of a cluster randomized clinical trial of Behavioral Activities Intervention (BE-ACTIV), a behavioral intervention for depression in nursing homes. Method. Twenty-three nursing homes randomized to BE-ACTIV or treatment as usual (TAU); 82 depressed long-term care residents recruited from these nursing homes. BE-ACTIV participants received 10 weeks of individual therapy after a 2-week baseline. TAU participants received weekly research visits. Follow-up assessments occurred at 3- and 6-month posttreatment. Results. BE-ACTIV group participants showed better diagnostic recovery at posttreatment in intent-to-treat analyses adjusted for clustering. They were more likely to be remitted than TAU participants at posttreatment and at 3-month posttreatment but not at 6 months. Self-reported depressive symptoms and functioning improved in both groups, but there were no significant treatment by time interactions in these variables. Discussion. BE-ACTIV was superior to TAU in moving residents to full remission from depression. The treatment was well received by nursing home staff and accepted by residents. A large proportion of participants remained symptomatic at posttreatment, despite taking one or more antidepressants. The results illustrate the potential power of an attentional intervention to improve self-reported mood and functioning, but also the difficulties related to both studying and implementing effective treatments in nursing homes. PMID:24691156

  17. A Randomized, Controlled Trial of the Impact of Alternative Dosing Schedules on the Immune Response to Human Rotavirus Vaccine in Rural Ghanaian Infants

    PubMed Central

    Armah, George; Lewis, Kristen D. C.; Cortese, Margaret M.; Parashar, Umesh D.; Ansah, Akosua; Gazley, Lauren; Victor, John C.; McNeal, Monica M.; Binka, Fred; Steele, A. Duncan

    2016-01-01

    Background. The recommended schedule for receipt of 2-dose human rotavirus vaccine (HRV) coincides with receipt of the first and second doses of diphtheria, pertussis, and tetanus vaccine (ie, 6 and 10 weeks of age, respectively). Alternative schedules and additional doses of HRV have been proposed and may improve vaccine performance in low-income countries. Methods. In this randomized trial in rural Ghana, HRV was administered at ages 6 and 10 weeks (group 1), 10 and 14 weeks (group 2), or 6, 10, and 14 weeks (group 3). We compared serum antirotavirus immunoglobulin A (IgA) seroconversion (≥20 U/mL) and geometric mean concentrations (GMCs) between group 1 and groups 2 and 3. Results. Ninety-three percent of participants (424 of 456) completed the study per protocol. In groups 1, 2, and 3, the IgA seroconversion frequencies among participants with IgA levels of <20 U/mL at baseline were 28.9%, 37.4%, and 43.4%, respectively (group 1 vs group 3, P = .014; group 1 vs group 2, P = .163). Postvaccination IgA GMCs were 22.1 U/mL, 26.5 U/mL, and 32.6 U/mL in groups 1, 2, and 3, respectively (group 1 vs group 3, P = .038; group 1 vs group 2, P = .304). Conclusions. A third dose of HRV resulted in increased seroconversion frequencies and GMCs, compared with 2 doses administered at 6 and 10 weeks of age. Since there is no correlate of protection, a postmarketing effectiveness study is required to determine whether the improvement in immune response translates into a public health benefit in low-income countries. Clinical Trials Registration. NCT015751. PMID:26823335

  18. Ten weeks of physical-cognitive-mindfulness training reduces fear-avoidance beliefs about work-related activity: Randomized controlled trial.

    PubMed

    Jay, Kenneth; Brandt, Mikkel; Jakobsen, Markus Due; Sundstrup, Emil; Berthelsen, Kasper Gymoese; Schraefel, Mc; Sjøgaard, Gisela; Andersen, Lars L

    2016-08-01

    People with chronic musculoskeletal pain often experience pain-related fear of movement and avoidance behavior. The Fear-Avoidance model proposes a possible mechanism at least partly explaining the development and maintenance of chronic pain. People who interpret pain during movement as being potentially harmful to the organism may initiate a vicious behavioral cycle by generating pain-related fear of movement accompanied by avoidance behavior and hyper-vigilance.This study investigates whether an individually adapted multifactorial approach comprised of biopsychosocial elements, with a focus on physical exercise, mindfulness, and education on pain and behavior, can decrease work-related fear-avoidance beliefs.As part of a large scale 10-week worksite randomized controlled intervention trial focusing on company initiatives to combat work-related musculoskeletal pain and stress, we evaluated fear-avoidance behavior in 112 female laboratory technicians with chronic neck, shoulder, upper back, lower back, elbow, and hand/wrist pain using the Fear-Avoidance Beliefs Questionnaire at baseline, before group allocation, and again at the post intervention follow-up 10 weeks later.A significant group by time interaction was observed (P < 0.05) for work-related fear-avoidance beliefs. The between-group difference at follow-up was -2.2 (-4.0 to -0.5), corresponding to a small to medium effect size (Cohen's d = 0.30).Our study shows that work-related, but not leisure time activity-related, fear-avoidance beliefs, as assessed by the Fear-avoidance Beliefs Questionnaire, can be significantly reduced by 10 weeks of physical-cognitive-mindfulness training in female laboratory technicians with chronic pain. PMID:27559939

  19. Random graphs with hidden color.

    PubMed

    Söderberg, Bo

    2003-07-01

    We propose and investigate a unifying class of sparse random graph models, based on a hidden coloring of edge-vertex incidences, extending an existing approach, random graphs with a given degree distribution, in a way that admits a nontrivial correlation structure in the resulting graphs. The approach unifies a number of existing random graph ensembles within a common general formalism, and allows for the analytic calculation of observable graph characteristics. In particular, generating function techniques are used to derive the size distribution of connected components (clusters) as well as the location of the percolation threshold where a giant component appears. PMID:12935185

  20. Random sequential adsorption on fractals

    NASA Astrophysics Data System (ADS)

    Ciesla, Michal; Barbasz, Jakub

    2012-07-01

    Irreversible adsorption of spheres on flat collectors having dimension d < 2 is studied. Molecules are adsorbed on Sierpinski's triangle and carpet-like fractals (1 < d < 2), and on general Cantor set (d < 1). Adsorption process is modeled numerically using random sequential adsorption (RSA) algorithm. The paper concentrates on measurement of fundamental properties of coverages, i.e., maximal random coverage ratio and density autocorrelation function, as well as RSA kinetics. Obtained results allow to improve phenomenological relation between maximal random coverage ratio and collector dimension. Moreover, simulations show that, in general, most of known dimensional properties of adsorbed monolayers are valid for non-integer dimensions.

  1. Random sequential adsorption on fractals.

    PubMed

    Ciesla, Michal; Barbasz, Jakub

    2012-07-28

    Irreversible adsorption of spheres on flat collectors having dimension d < 2 is studied. Molecules are adsorbed on Sierpinski's triangle and carpet-like fractals (1 < d < 2), and on general Cantor set (d < 1). Adsorption process is modeled numerically using random sequential adsorption (RSA) algorithm. The paper concentrates on measurement of fundamental properties of coverages, i.e., maximal random coverage ratio and density autocorrelation function, as well as RSA kinetics. Obtained results allow to improve phenomenological relation between maximal random coverage ratio and collector dimension. Moreover, simulations show that, in general, most of known dimensional properties of adsorbed monolayers are valid for non-integer dimensions. PMID:22852643

  2. Lowest eigenvalues of random Hamiltonians

    SciTech Connect

    Shen, J. J.; Zhao, Y. M.; Arima, A.; Yoshinaga, N.

    2008-05-15

    In this article we study the lowest eigenvalues of random Hamiltonians for both fermion and boson systems. We show that an empirical formula of evaluating the lowest eigenvalues of random Hamiltonians in terms of energy centroids and widths of eigenvalues is applicable to many different systems. We improve the accuracy of the formula by considering the third central moment. We show that these formulas are applicable not only to the evaluation of the lowest energy but also to the evaluation of excited energies of systems under random two-body interactions.

  3. Covariate-based constrained randomization of group-randomized trials.

    PubMed

    Moulton, Lawrence H

    2004-01-01

    Group-randomized study designs are useful when individually randomized designs are either not possible, or will not be able to estimate the parameters of interest. Blocked and/or stratified (for example, pair-matched) designs have been used, and their properties statistically evaluated by many researchers. Group-randomized trials often have small numbers of experimental units, and strong, geographically induced between-unit correlation, which increase the chance of obtaining a "bad" randomization outcome. This article describes a procedure--random selection from a list of acceptable allocations--to allocate treatment conditions in a way that ensures balance on relevant covariates. Numerous individual- and group-level covariates can be balanced using exact or caliper criteria. Simulation results indicate that this method has good frequency properties, but some care may be needed not to overly constrain the randomization. There is a trade-off between achieving good balance through a highly constrained design, and jeopardizing the appearance of impartiality of the investigator and potentially departing from the nominal Type I error. PMID:16279255

  4. Quantifying randomness in real networks

    PubMed Central

    Orsini, Chiara; Dankulov, Marija M.; Colomer-de-Simón, Pol; Jamakovic, Almerima; Mahadevan, Priya; Vahdat, Amin; Bassler, Kevin E.; Toroczkai, Zoltán; Boguñá, Marián; Caldarelli, Guido; Fortunato, Santo; Krioukov, Dmitri

    2015-01-01

    Represented as graphs, real networks are intricate combinations of order and disorder. Fixing some of the structural properties of network models to their values observed in real networks, many other properties appear as statistical consequences of these fixed observables, plus randomness in other respects. Here we employ the dk-series, a complete set of basic characteristics of the network structure, to study the statistical dependencies between different network properties. We consider six real networks—the Internet, US airport network, human protein interactions, technosocial web of trust, English word network, and an fMRI map of the human brain—and find that many important local and global structural properties of these networks are closely reproduced by dk-random graphs whose degree distributions, degree correlations and clustering are as in the corresponding real network. We discuss important conceptual, methodological, and practical implications of this evaluation of network randomness, and release software to generate dk-random graphs. PMID:26482121

  5. Scattering from a random surface

    SciTech Connect

    Abarbanel, H.D.I.

    1980-11-01

    We give a formulation of the problem of propagation of scalar waves over a random surface. By a judicious choice of variables we are able to show that this situation is equivalent to propagation of these waves through a medium of random fluctuations with fluctuating source and receiver. The wave equation in the new coordinates has an additional term, the fluctuation operator, which depends on derivatives of the surface in space and time. An expansion in the fluctuation operator is given which guarantees the desired boundary conditions at every order. We treat both the cases where the surface is time dependent, such as the sea surface, or fixed in time. Also discussed is the situation where the source and receiver lie between the random surface and another, possibly also random, surface. In detail we consider acoustic waves for which the surfaces are pressure release. The method is directly applicable to electromagnetic waves and other boundary conditions.

  6. A Randomized Central Limit Theorem

    NASA Astrophysics Data System (ADS)

    Eliazar, Iddo; Klafter, Joseph

    2010-05-01

    The Central Limit Theorem (CLT), one of the most elemental pillars of Probability Theory and Statistical Physics, asserts that: the universal probability law of large aggregates of independent and identically distributed random summands with zero mean and finite variance, scaled by the square root of the aggregate-size (√{n}), is Gaussian. The scaling scheme of the CLT is deterministic and uniform - scaling all aggregate-summands by the common and deterministic factor √{n}. This Letter considers scaling schemes which are stochastic and non-uniform, and presents a "Randomized Central Limit Theorem" (RCLT): we establish a class of random scaling schemes which yields universal probability laws of large aggregates of independent and identically distributed random summands. The RCLT universal probability laws, in turn, are the one-sided and the symmetric Lévy laws.

  7. Quantifying randomness in real networks

    NASA Astrophysics Data System (ADS)

    Orsini, Chiara; Dankulov, Marija M.; Colomer-de-Simón, Pol; Jamakovic, Almerima; Mahadevan, Priya; Vahdat, Amin; Bassler, Kevin E.; Toroczkai, Zoltán; Boguñá, Marián; Caldarelli, Guido; Fortunato, Santo; Krioukov, Dmitri

    2015-10-01

    Represented as graphs, real networks are intricate combinations of order and disorder. Fixing some of the structural properties of network models to their values observed in real networks, many other properties appear as statistical consequences of these fixed observables, plus randomness in other respects. Here we employ the dk-series, a complete set of basic characteristics of the network structure, to study the statistical dependencies between different network properties. We consider six real networks--the Internet, US airport network, human protein interactions, technosocial web of trust, English word network, and an fMRI map of the human brain--and find that many important local and global structural properties of these networks are closely reproduced by dk-random graphs whose degree distributions, degree correlations and clustering are as in the corresponding real network. We discuss important conceptual, methodological, and practical implications of this evaluation of network randomness, and release software to generate dk-random graphs.

  8. Quantifying randomness in real networks.

    PubMed

    Orsini, Chiara; Dankulov, Marija M; Colomer-de-Simón, Pol; Jamakovic, Almerima; Mahadevan, Priya; Vahdat, Amin; Bassler, Kevin E; Toroczkai, Zoltán; Boguñá, Marián; Caldarelli, Guido; Fortunato, Santo; Krioukov, Dmitri

    2015-01-01

    Represented as graphs, real networks are intricate combinations of order and disorder. Fixing some of the structural properties of network models to their values observed in real networks, many other properties appear as statistical consequences of these fixed observables, plus randomness in other respects. Here we employ the dk-series, a complete set of basic characteristics of the network structure, to study the statistical dependencies between different network properties. We consider six real networks--the Internet, US airport network, human protein interactions, technosocial web of trust, English word network, and an fMRI map of the human brain--and find that many important local and global structural properties of these networks are closely reproduced by dk-random graphs whose degree distributions, degree correlations and clustering are as in the corresponding real network. We discuss important conceptual, methodological, and practical implications of this evaluation of network randomness, and release software to generate dk-random graphs. PMID:26482121

  9. Random Selection for Drug Screening

    SciTech Connect

    Center for Human Reliability Studies

    2007-05-01

    Sampling is the process of choosing some members out of a group or population. Probablity sampling, or random sampling, is the process of selecting members by chance with a known probability of each individual being chosen.

  10. Control theory for random systems

    NASA Technical Reports Server (NTRS)

    Bryson, A. E., Jr.

    1972-01-01

    A survey is presented of the current knowledge available for designing and predicting the effectiveness of controllers for dynamic systems which can be modeled by ordinary differential equations. A short discussion of feedback control is followed by a description of deterministic controller design and the concept of system state. The need for more realistic disturbance models led to the use of stochastic process concepts, in particular the Gauss-Markov process. A compensator controlled system, with random forcing functions, random errors in the measurements, and random initial conditions, is treated as constituting a Gauss-Markov random process; hence the mean-square behavior of the controlled system is readily predicted. As an example, a compensator is designed for a helicopter to maintain it in hover in a gusty wind over a point on the ground.

  11. Quantum-noise randomized ciphers

    NASA Astrophysics Data System (ADS)

    Nair, Ranjith; Yuen, Horace P.; Corndorf, Eric; Eguchi, Takami; Kumar, Prem

    2006-11-01

    We review the notion of a classical random cipher and its advantages. We sharpen the usual description of random ciphers to a particular mathematical characterization suggested by the salient feature responsible for their increased security. We describe a concrete system known as αη and show that it is equivalent to a random cipher in which the required randomization is affected by coherent-state quantum noise. We describe the currently known security features of αη and similar systems, including lower bounds on the unicity distances against ciphertext-only and known-plaintext attacks. We show how αη used in conjunction with any standard stream cipher such as the Advanced Encryption Standard provides an additional, qualitatively different layer of security from physical encryption against known-plaintext attacks on the key. We refute some claims in the literature that αη is equivalent to a nonrandom stream cipher.

  12. Quantum-noise randomized ciphers

    SciTech Connect

    Nair, Ranjith; Yuen, Horace P.; Kumar, Prem; Corndorf, Eric; Eguchi, Takami

    2006-11-15

    We review the notion of a classical random cipher and its advantages. We sharpen the usual description of random ciphers to a particular mathematical characterization suggested by the salient feature responsible for their increased security. We describe a concrete system known as {alpha}{eta} and show that it is equivalent to a random cipher in which the required randomization is affected by coherent-state quantum noise. We describe the currently known security features of {alpha}{eta} and similar systems, including lower bounds on the unicity distances against ciphertext-only and known-plaintext attacks. We show how {alpha}{eta} used in conjunction with any standard stream cipher such as the Advanced Encryption Standard provides an additional, qualitatively different layer of security from physical encryption against known-plaintext attacks on the key. We refute some claims in the literature that {alpha}{eta} is equivalent to a nonrandom stream cipher.

  13. Diffraction by random Ronchi gratings.

    PubMed

    Torcal-Milla, Francisco Jose; Sanchez-Brea, Luis Miguel

    2016-08-01

    In this work, we obtain analytical expressions for the near-and far-field diffraction of random Ronchi diffraction gratings where the slits of the grating are randomly displaced around their periodical positions. We theoretically show that the effect of randomness in the position of the slits of the grating produces a decrease of the contrast and even disappearance of the self-images for high randomness level at the near field. On the other hand, it cancels high-order harmonics in far field, resulting in only a few central diffraction orders. Numerical simulations by means of the Rayleigh-Sommerfeld diffraction formula are performed in order to corroborate the analytical results. These results are of interest for industrial and technological applications where manufacture errors need to be considered. PMID:27505363

  14. Experimental evidence of quantum randomness incomputability

    SciTech Connect

    Calude, Cristian S.; Dinneen, Michael J.; Dumitrescu, Monica; Svozil, Karl

    2010-08-15

    In contrast with software-generated randomness (called pseudo-randomness), quantum randomness can be proven incomputable; that is, it is not exactly reproducible by any algorithm. We provide experimental evidence of incomputability--an asymptotic property--of quantum randomness by performing finite tests of randomness inspired by algorithmic information theory.

  15. Digital random-number generator

    NASA Technical Reports Server (NTRS)

    Brocker, D. H.

    1973-01-01

    For binary digit array of N bits, use N noise sources to feed N nonlinear operators; each flip-flop in digit array is set by nonlinear operator to reflect whether amplitude of generator which feeds it is above or below mean value of generated noise. Fixed-point uniform distribution random number generation method can also be used to generate random numbers with other than uniform distribution.

  16. On Pfaffian Random Point Fields

    NASA Astrophysics Data System (ADS)

    Kargin, V.

    2014-02-01

    We study Pfaffian random point fields by using the Moore-Dyson quaternion determinants. First, we give sufficient conditions that ensure that a self-dual quaternion kernel defines a valid random point field, and then we prove a CLT for Pfaffian point fields. The proofs are based on a new quaternion extension of the Cauchy-Binet determinantal identity. In addition, we derive the Fredholm determinantal formulas for the Pfaffian point fields which use the quaternion determinant.

  17. Quasi-Random Sequence Generators.

    Energy Science and Technology Software Center (ESTSC)

    1994-03-01

    Version 00 LPTAU generates quasi-random sequences. The sequences are uniformly distributed sets of L=2**30 points in the N-dimensional unit cube: I**N=[0,1]. The sequences are used as nodes for multidimensional integration, as searching points in global optimization, as trial points in multicriteria decision making, as quasi-random points for quasi Monte Carlo algorithms.

  18. Randomness and degrees of irregularity.

    PubMed Central

    Pincus, S; Singer, B H

    1996-01-01

    The fundamental question "Are sequential data random?" arises in myriad contexts, often with severe data length constraints. Furthermore, there is frequently a critical need to delineate nonrandom sequences in terms of closeness to randomness--e.g., to evaluate the efficacy of therapy in medicine. We address both these issues from a computable framework via a quantification of regularity. ApEn (approximate entropy), defining maximal randomness for sequences of arbitrary length, indicating the applicability to sequences as short as N = 5 points. An infinite sequence formulation of randomness is introduced that retains the operational (and computable) features of the finite case. In the infinite sequence setting, we indicate how the "foundational" definition of independence in probability theory, and the definition of normality in number theory, reduce to limit theorems without rates of convergence, from which we utilize ApEn to address rates of convergence (of a deficit from maximal randomness), refining the aforementioned concepts in a computationally essential manner. Representative applications among many are indicated to assess (i) random number generation output; (ii) well-shuffled arrangements; and (iii) (the quality of) bootstrap replicates. PMID:11607637

  19. Phase Transitions on Random Lattices: How Random is Topological Disorder?

    NASA Astrophysics Data System (ADS)

    Barghathi, Hatem; Vojta, Thomas

    2015-03-01

    We study the effects of topological (connectivity) disorder on phase transitions. We identify a broad class of random lattices whose disorder fluctuations decay much faster with increasing length scale than those of generic random systems, yielding a wandering exponent of ω = (d - 1) / (2 d) in d dimensions. The stability of clean critical points is thus governed by the criterion (d + 1) ν > 2 rather than the usual Harris criterion dν > 2 , making topological disorder less relevant than generic randomness. The Imry-Ma criterion is also modified, allowing first-order transitions to survive in all dimensions d > 1 . These results explain a host of puzzling violations of the original criteria for equilibrium and nonequilibrium phase transitions on random lattices. We discuss applications, and we illustrate our theory by computer simulations of random Voronoi and other lattices. This work was supported by the NSF under Grant Nos. DMR-1205803 and PHYS-1066293. We acknowledge the hospitality of the Aspen Center for Physics.

  20. Full randomness from arbitrarily deterministic events.

    PubMed

    Gallego, Rodrigo; Masanes, Lluis; De La Torre, Gonzalo; Dhara, Chirag; Aolita, Leandro; Acín, Antonio

    2013-01-01

    Do completely unpredictable events exist? Classical physics excludes fundamental randomness. Although quantum theory makes probabilistic predictions, this does not imply that nature is random, as randomness should be certified without relying on the complete structure of the theory being used. Bell tests approach the question from this perspective. However, they require prior perfect randomness, falling into a circular reasoning. A Bell test that generates perfect random bits from bits possessing high-but less than perfect-randomness has recently been obtained. Yet, the main question remained open: does any initial randomness suffice to certify perfect randomness? Here we show that this is indeed the case. We provide a Bell test that uses arbitrarily imperfect random bits to produce bits that are, under the non-signalling principle assumption, perfectly random. This provides the first protocol attaining full randomness amplification. Our results have strong implications onto the debate of whether there exist events that are fully random. PMID:24173040

  1. On Convergent Probability of a Random Walk

    ERIC Educational Resources Information Center

    Lee, Y.-F.; Ching, W.-K.

    2006-01-01

    This note introduces an interesting random walk on a straight path with cards of random numbers. The method of recurrent relations is used to obtain the convergent probability of the random walk with different initial positions.

  2. Wave propagation through a random medium - The random slab problem

    NASA Technical Reports Server (NTRS)

    Acquista, C.

    1978-01-01

    The first-order smoothing approximation yields integral equations for the mean and the two-point correlation function of a wave in a random medium. A method is presented for the approximate solution of these equations that combines features of the eiconal approximation and of the Born expansion. This method is applied to the problem of reflection and transmission of a plane wave by a slab of a random medium. Both the mean wave and the covariance are calculated to determine the reflected and transmitted amplitudes and intensities.

  3. Cover times of random searches

    NASA Astrophysics Data System (ADS)

    Chupeau, Marie; Bénichou, Olivier; Voituriez, Raphaël

    2015-10-01

    How long must one undertake a random search to visit all sites of a given domain? This time, known as the cover time, is a key observable to quantify the efficiency of exhaustive searches, which require a complete exploration of an area and not only the discovery of a single target. Examples range from immune-system cells chasing pathogens to animals harvesting resources, from robotic exploration for cleaning or demining to the task of improving search algorithms. Despite its broad relevance, the cover time has remained elusive and so far explicit results have been scarce and mostly limited to regular random walks. Here we determine the full distribution of the cover time for a broad range of random search processes, including Lévy strategies, intermittent strategies, persistent random walks and random walks on complex networks, and reveal its universal features. We show that for all these examples the mean cover time can be minimized, and that the corresponding optimal strategies also minimize the mean search time for a single target, unambiguously pointing towards their robustness.

  4. Random root movements in weightlessness.

    PubMed

    Johnsson, A; Karlsson, C; Iversen, T H; Chapman, D K

    1996-02-01

    The dynamics of root growth was studied in weightlessness. In the absence of the gravitropic reference direction during weightlessness, root movements could be controlled by spontaneous growth processes, without any corrective growth induced by the gravitropic system. If truly random of nature, the bending behavior should follow so-called 'random walk' mathematics during weightlessness. Predictions from this hypothesis were critically tested. In a Spacelab ESA-experiment, denoted RANDOM and carried out during the IML-2 Shuttle flight in July 1994, the growth of garden cress (Lepidium sativum) roots was followed by time lapse photography at 1-h intervals. The growth pattern was recorded for about 20 h. Root growth was significantly smaller in weightlessness as compared to gravity (control) conditions. It was found that the roots performed spontaneous movements in weightlessness. The average direction of deviation of the plants consistently stayed equal to zero, despite these spontaneous movements. The average squared deviation increased linearly with time as predicted theoretically (but only for 8-10 h). Autocorrelation calculations showed that bendings of the roots, as determined from the 1-h photographs, were uncorrelated after about a 2-h interval. It is concluded that random processes play an important role in root growth. Predictions from a random walk hypothesis as to the growth dynamics could explain parts of the growth patterns recorded. This test of the hypothesis required microgravity conditions as provided for in a space experiment. PMID:11541141

  5. Propagation in multiscale random media

    NASA Astrophysics Data System (ADS)

    Balk, Alexander M.

    2003-10-01

    Many studies consider media with microstructure, which has variations on some microscale, while the macroproperties are under investigation. Sometimes the medium has several microscales, all of them being much smaller than the macroscale. Sometimes the variations on the macroscale are also included, which are taken into account by some procedures, like WKB or geometric optics. What if the medium has variations on all scales from microscale to macroscale? This situation occurs in several practical problems. The talk is about such situations, in particular, passive tracer in a random velocity field, wave propagation in a random medium, Schrödinger equation with random potential. To treat such problems we have developed the statistical near-identity transformation. We find anomalous attenuation of the pulse propagating in a multiscale medium.

  6. A Randomized Experiment Comparing Random and Cutoff-Based Assignment

    ERIC Educational Resources Information Center

    Shadish, William R.; Galindo, Rodolfo; Wong, Vivian C.; Steiner, Peter M.; Cook, Thomas D.

    2011-01-01

    In this article, we review past studies comparing randomized experiments to regression discontinuity designs, mostly finding similar results, but with significant exceptions. The latter might be due to potential confounds of study characteristics with assignment method or with failure to estimate the same parameter over methods. In this study, we…

  7. Relatively Random: Context Effects on Perceived Randomness and Predicted Outcomes

    ERIC Educational Resources Information Center

    Matthews, William J.

    2013-01-01

    This article concerns the effect of context on people's judgments about sequences of chance outcomes. In Experiment 1, participants judged whether sequences were produced by random, mechanical processes (such as a roulette wheel) or skilled human action (such as basketball shots). Sequences with lower alternation rates were judged more likely to…

  8. Neutron transport in random media

    SciTech Connect

    Makai, M.

    1996-08-01

    The survey reviews the methods available in the literature which allow a discussion of corium recriticality after a severe accident and a characterization of the corium. It appears that to date no one has considered the eigenvalue problem, though for the source problem several approaches have been proposed. The mathematical formulation of a random medium may be approached in different ways. Based on the review of the literature, we can draw three basic conclusions. The problem of static, random perturbations has been solved. The static case is tractable by the Monte Carlo method. There is a specific time dependent case for which the average flux is given as a series expansion.

  9. Random sequential adsorption of tetramers

    NASA Astrophysics Data System (ADS)

    Cieśla, Michał

    2013-07-01

    Adsorption of a tetramer built of four identical spheres was studied numerically using the random sequential adsorption (RSA) algorithm. Tetramers were adsorbed on a two-dimensional, flat and homogeneous surface. Two different models of the adsorbate were investigated: a rhomboid and a square one; monomer centres were put on vertices of rhomboids and squares, respectively. Numerical simulations allow us to establish the maximal random coverage ratio as well as the available surface function (ASF), which is crucial for determining kinetics of the adsorption process. These results were compared with data obtained experimentally for KfrA plasmid adsorption. Additionally, the density autocorrelation function was measured.

  10. Molecular random tilings as glasses

    PubMed Central

    Garrahan, Juan P.; Stannard, Andrew; Blunt, Matthew O.; Beton, Peter H.

    2009-01-01

    We have recently shown that p-terphenyl-3,5,3′,5′-tetracarboxylic acid adsorbed on graphite self-assembles into a two-dimensional rhombus random tiling. This tiling is close to ideal, displaying long-range correlations punctuated by sparse localized tiling defects. In this article we explore the analogy between dynamic arrest in this type of random tilings and that of structural glasses. We show that the structural relaxation of these systems is via the propagation–reaction of tiling defects, giving rise to dynamic heterogeneity. We study the scaling properties of the dynamics and discuss connections with kinetically constrained models of glasses. PMID:19720990

  11. Mode statistics in random lasers

    SciTech Connect

    Zaitsev, Oleg

    2006-12-15

    Representing an ensemble of random lasers with an ensemble of random matrices, we compute the average number of lasing modes and its fluctuations. The regimes of weak and strong coupling of the passive resonator to the environment are considered. In the latter case, contrary to an earlier claim in the literature, we do not find a power-law dependence of the average mode number on the pump strength. For the relative fluctuations, however, a power law can be established. It is shown that, due to the mode competition, the distribution of the number of excited modes over an ensemble of lasers is not binomial.

  12. Random organization and plastic depinning

    SciTech Connect

    Reichhardt, Charles; Reichhardt, Cynthia

    2008-01-01

    We provide evidence that the general phenomenon of plastic depinning can be described as an absorbing phase transition, and shows the same features as the random organization which was recently studied in periodically driven particle systems [L. Corte, Nature Phys. 4, 420 (2008)]. In the plastic flow system, the pinned regime corresponds to the absorbing state and the moving state corresponds to the fluctuating state. When an external force is suddenly applied, the system eventually organizes into one of these two states with a time scale that diverges as a power law at a nonequilibrium transition. We propose a simple experiment to test for this transition in systems with random disorder.

  13. Synchronizability of random rectangular graphs

    SciTech Connect

    Estrada, Ernesto Chen, Guanrong

    2015-08-15

    Random rectangular graphs (RRGs) represent a generalization of the random geometric graphs in which the nodes are embedded into hyperrectangles instead of on hypercubes. The synchronizability of RRG model is studied. Both upper and lower bounds of the eigenratio of the network Laplacian matrix are determined analytically. It is proven that as the rectangular network is more elongated, the network becomes harder to synchronize. The synchronization processing behavior of a RRG network of chaotic Lorenz system nodes is numerically investigated, showing complete consistence with the theoretical results.

  14. Effect of an office worksite-based yoga program on heart rate variability: A randomized controlled trial

    PubMed Central

    2011-01-01

    Background Chronic work-related stress is a significant and independent risk factor for cardiovascular and metabolic diseases and associated mortality, particularly when compounded by a sedentary work environment. Heart rate variability (HRV) provides an estimate of parasympathetic and sympathetic autonomic control, and can serve as a marker of physiological stress. Hatha yoga is a physically demanding practice that can help to reduce stress; however, time constraints incurred by work and family life may limit participation. The purpose of the present study is to determine if a 10-week, worksite-based yoga program delivered during lunch hour can improve resting HRV and related physical and psychological parameters in sedentary office workers. Methods and design This is a parallel-arm RCT that will compare the outcomes of participants assigned to the experimental treatment group (yoga) to those assigned to a no-treatment control group. Participants randomized to the experimental condition will engage in a 10-week yoga program delivered at their place of work. The yoga sessions will be group-based, prescribed three times per week during lunch hour, and will be led by an experienced yoga instructor. The program will involve teaching beginner students safely and progressively over 10 weeks a yoga sequence that incorporates asanas (poses and postures), vinyasa (exercises), pranayama (breathing control) and meditation. The primary outcome of this study is the high frequency (HF) spectral power component of HRV (measured in absolute units; i.e. ms2), a measure of parasympathetic autonomic control. Secondary outcomes include additional frequency and time domains of HRV, and measures of physical functioning and psychological health status. Measures will be collected prior to and following the intervention period, and at 6 months follow-up to determine the effect of intervention withdrawal. Discussion This study will determine the effect of worksite-based yoga practice on

  15. A Mixed Effects Randomized Item Response Model

    ERIC Educational Resources Information Center

    Fox, J.-P.; Wyrick, Cheryl

    2008-01-01

    The randomized response technique ensures that individual item responses, denoted as true item responses, are randomized before observing them and so-called randomized item responses are observed. A relationship is specified between randomized item response data and true item response data. True item response data are modeled with a (non)linear…

  16. Undecidability Theorem and Quantum Randomness

    NASA Astrophysics Data System (ADS)

    Berezin, Alexander A.

    2005-04-01

    As scientific folklore has it, Kurt Godel was once annoyed by question whether he sees any link between his Undecidability Theorem (UT) and Uncertainty Relationship. His reaction, however, may indicate that he probably felt that such a hidden link could indeed exist but he was unable clearly formulate it. Informational version of UT (G.J.Chaitin) states impossibility to rule out algorithmic compressibility of arbitrary digital string. Thus, (mathematical) randomness can only be disproven, not proven. Going from mathematical to physical (mainly quantum) randomness, we encounter seemingly random acts of radioactive decays of isotopes (such as C14), emission of excited atoms, tunneling effects, etc. However, our notion of quantum randomness (QR) may likely hit similarly formidable wall of physical version of UT leading to seemingly bizarre ideas such as Everett many world model (D.Deutsch) or backward causation (J.A.Wheeler). Resolution may potentially lie in admitting some form of Aristotelean final causation (AFC) as an ultimate foundational principle (G.W.Leibniz) connecting purely mathematical (Platonic) grounding aspects with it physically observable consequences, such as plethora of QR effects. Thus, what we interpret as QR may eventually be manifestation of AFC in which UT serves as delivery vehicle. Another example of UT/QR/AFC connection is question of identity (indistinguishability) of elementary particles (are all electrons exactly the same or just approximately so to a very high degree?).

  17. Are quasar redshifts randomly distributed

    NASA Technical Reports Server (NTRS)

    Weymann, R. J.; Boroson, T.; Scargle, J. D.

    1978-01-01

    A statistical analysis of possible clumping (not periodicity) of emission line redshifts of QSO's shows the available data to be compatible with random fluctuations of a smooth, non-clumped distribution. This result is demonstrated with Monte Carlo simulations as well as with the Kolmogorov-Smirnov test. It is in complete disagreement with the analysis by Varshni, which is shown to be incorrect.

  18. Randomized Item Response Theory Models

    ERIC Educational Resources Information Center

    Fox, Jean-Paul

    2005-01-01

    The randomized response (RR) technique is often used to obtain answers on sensitive questions. A new method is developed to measure latent variables using the RR technique because direct questioning leads to biased results. Within the RR technique is the probability of the true response modeled by an item response theory (IRT) model. The RR…

  19. Common Randomness Principles of Secrecy

    ERIC Educational Resources Information Center

    Tyagi, Himanshu

    2013-01-01

    This dissertation concerns the secure processing of distributed data by multiple terminals, using interactive public communication among themselves, in order to accomplish a given computational task. In the setting of a probabilistic multiterminal source model in which several terminals observe correlated random signals, we analyze secure…

  20. Entropy of random entangling surfaces

    NASA Astrophysics Data System (ADS)

    Solodukhin, Sergey N.

    2012-09-01

    We consider the situation when a globally defined four-dimensional field system is separated on two entangled sub-systems by a dynamical (random) two-dimensional surface. The reduced density matrix averaged over ensemble of random surfaces of fixed area and the corresponding average entropy are introduced. The average entanglement entropy is analyzed for a generic conformal field theory in four dimensions. Two important particular cases are considered. In the first, both the intrinsic metric on the entangling surface and the spacetime metric are fluctuating. An important example of this type is when the entangling surface is a black hole horizon, the fluctuations of which cause necessarily the fluctuations in the spacetime geometry. In the second case, the spacetime is considered to be fixed. The detailed analysis is carried out for the random entangling surfaces embedded in flat Minkowski spacetime. In all cases, the problem reduces to an effectively two-dimensional problem of random surfaces which can be treated by means of the well-known conformal methods. Focusing on the logarithmic terms in the entropy, we predict the appearance of a new ln ln(A) term. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical in honour of Stuart Dowker's 75th birthday devoted to ‘Applications of zeta functions and other spectral functions in mathematics and physics’.

  1. Garnet Random-Access Memory

    NASA Technical Reports Server (NTRS)

    Katti, Romney R.

    1995-01-01

    Random-access memory (RAM) devices of proposed type exploit magneto-optical properties of magnetic garnets exhibiting perpendicular anisotropy. Magnetic writing and optical readout used. Provides nonvolatile storage and resists damage by ionizing radiation. Because of basic architecture and pinout requirements, most likely useful as small-capacity memory devices.

  2. Models of random graph hierarchies

    NASA Astrophysics Data System (ADS)

    Paluch, Robert; Suchecki, Krzysztof; Hołyst, Janusz A.

    2015-10-01

    We introduce two models of inclusion hierarchies: random graph hierarchy (RGH) and limited random graph hierarchy (LRGH). In both models a set of nodes at a given hierarchy level is connected randomly, as in the Erdős-Rényi random graph, with a fixed average degree equal to a system parameter c. Clusters of the resulting network are treated as nodes at the next hierarchy level and they are connected again at this level and so on, until the process cannot continue. In the RGH model we use all clusters, including those of size 1, when building the next hierarchy level, while in the LRGH model clusters of size 1 stop participating in further steps. We find that in both models the number of nodes at a given hierarchy level h decreases approximately exponentially with h. The height of the hierarchy H, i.e. the number of all hierarchy levels, increases logarithmically with the system size N, i.e. with the number of nodes at the first level. The height H decreases monotonically with the connectivity parameter c in the RGH model and it reaches a maximum for a certain c max in the LRGH model. The distribution of separate cluster sizes in the LRGH model is a power law with an exponent about - 1.25. The above results follow from approximate analytical calculations and have been confirmed by numerical simulations.

  3. Plated wire random access memories

    NASA Technical Reports Server (NTRS)

    Gouldin, L. D.

    1975-01-01

    A program was conducted to construct 4096-work by 18-bit random access, NDRO-plated wire memory units. The memory units were subjected to comprehensive functional and environmental tests at the end-item level to verify comformance with the specified requirements. A technical description of the unit is given, along with acceptance test data sheets.

  4. Universality in random quantum networks

    NASA Astrophysics Data System (ADS)

    Novotný, Jaroslav; Alber, Gernot; Jex, Igor

    2015-12-01

    Networks constitute efficient tools for assessing universal features of complex systems. In physical contexts, classical as well as quantum networks are used to describe a wide range of phenomena, such as phase transitions, intricate aspects of many-body quantum systems, or even characteristic features of a future quantum internet. Random quantum networks and their associated directed graphs are employed for capturing statistically dominant features of complex quantum systems. Here, we develop an efficient iterative method capable of evaluating the probability of a graph being strongly connected. It is proven that random directed graphs with constant edge-establishing probability are typically strongly connected, i.e., any ordered pair of vertices is connected by a directed path. This typical topological property of directed random graphs is exploited to demonstrate universal features of the asymptotic evolution of large random qubit networks. These results are independent of our knowledge of the details of the network topology. These findings suggest that other highly complex networks, such as a future quantum internet, may also exhibit similar universal properties.

  5. Random trinomial tree models and vanilla options

    NASA Astrophysics Data System (ADS)

    Ganikhodjaev, Nasir; Bayram, Kamola

    2013-09-01

    In this paper we introduce and study random trinomial model. The usual trinomial model is prescribed by triple of numbers (u, d, m). We call the triple (u, d, m) an environment of the trinomial model. A triple (Un, Dn, Mn), where {Un}, {Dn} and {Mn} are the sequences of independent, identically distributed random variables with 0 < Dn < 1 < Un and Mn = 1 for all n, is called a random environment and trinomial tree model with random environment is called random trinomial model. The random trinomial model is considered to produce more accurate results than the random binomial model or usual trinomial model.

  6. Entanglement generation of nearly random operators.

    PubMed

    Weinstein, Yaakov S; Hellberg, C Stephen

    2005-07-15

    We study the entanglement generation of operators whose statistical properties approach those of random matrices but are restricted in some way. These include interpolating ensemble matrices, where the interval of the independent random parameters are restricted, pseudorandom operators, where there are far fewer random parameters than required for random matrices, and quantum chaotic evolution. Restricting randomness in different ways allows us to probe connections between entanglement and randomness. We comment on which properties affect entanglement generation and discuss ways of efficiently producing random states on a quantum computer. PMID:16090726

  7. Random density matrices versus random evolution of open system

    NASA Astrophysics Data System (ADS)

    Pineda, Carlos; Seligman, Thomas H.

    2015-10-01

    We present and compare two families of ensembles of random density matrices. The first, static ensemble, is obtained foliating an unbiased ensemble of density matrices. As criterion we use fixed purity as the simplest example of a useful convex function. The second, dynamic ensemble, is inspired in random matrix models for decoherence where one evolves a separable pure state with a random Hamiltonian until a given value of purity in the central system is achieved. Several families of Hamiltonians, adequate for different physical situations, are studied. We focus on a two qubit central system, and obtain exact expressions for the static case. The ensemble displays a peak around Werner-like states, modulated by nodes on the degeneracies of the density matrices. For moderate and strong interactions good agreement between the static and the dynamic ensembles is found. Even in a model where one qubit does not interact with the environment excellent agreement is found, but only if there is maximal entanglement with the interacting one. The discussion is started recalling similar considerations for scattering theory. At the end, we comment on the reach of the results for other convex functions of the density matrix, and exemplify the situation with the von Neumann entropy.

  8. A Randomized Trial of Contingency Management for Adolescent Marijuana Abuse and Dependence

    PubMed Central

    Stanger, Catherine; Budney, Alan J.; Kamon, Jody L.; Thostensen, Jeff

    2009-01-01

    An initial efficacy test of an innovative behavioral outpatient treatment model for adolescents with problematic use of marijuana enrolled 69 adolescents, aged 14–18, and randomly assigned them to one of two treatment conditions. Both conditions received individualized Motivational Enhancement and Cognitive Behavioral Therapy (MET/CBT) and a twice-weekly drug-testing program. The experimental contingency management condition involved a clinic delivered, abstinence-based incentive program, and weekly behavioral parent training sessions that included a parent-delivered, abstinence-based, substance monitoring contract. The comparison condition included an attendance-based incentive program, and weekly psychoeducational parent sessions. Follow-up assessments were performed at 3, 6, 9 months post-treatment. The experimental condition showed greater marijuana abstinence during treatment, e.g., 7.6 vs. 5.1 continuous weeks and 50% vs. 18% achieved ≥ 10 weeks of abstinence. Improvements were found in parenting and youth psychopathology across treatment conditions, and improvements in negative parenting uniquely predicted post treatment abstinence. The outcomes observed in the experimental condition are consistent with adult substance dependence treatment literature, and suggest that integrating CM abstinence-based approaches with other empirically-based outpatient interventions provides an alternative and efficacious treatment model for adolescent substance abuse/dependence. Replication and continued development of more potent interventions remain needed to further advance the development of effective substance abuse treatments for adolescents. PMID:19717250

  9. Service learning in medical and nursing training: a randomized controlled trial.

    PubMed

    Leung, A Y M; Chan, S S C; Kwan, C W; Cheung, M K T; Leung, S S K; Fong, D Y T

    2012-10-01

    The purpose of this study was to explore the long term effect of a service learning project on medical and nursing students' knowledge in aging and their attitudes toward older adults. A total of 124 students were recruited and then randomized to intervention group (IG) and control group (CG). A pre-and-post-intervention design measured students' knowledge in aging (using modified Palmore's Fact on Aging Quiz) and attitudes toward older adults (using Kogan's Old People Scale). A total of 103 students completed all the activities and questionnaires. After the intervention, there were significant differences between the IG and CG on Palmore's mental health (MH) (P = .04), Palmore's total score (P = .02) and Kogan's negative attitudes toward older adults (P = .001). All students increased their positive attitude toward older adults after the intervention. However, both the IG and CG showed a decrease in positive attitudes 1 month after the interventon, and such decrease varied, depending on the programme which students attended. The current study showed that the 10-week service learning activities significantly increased medical and nursing students' overall knowledge of aging and their understanding of mental health needs in old age, and reduced their negative attitudes toward older adults. However, the effect is not long-lasting. On the other hand, its effect on positive attitudes toward older adults cannot be concluded. Periodic contacts with older adults via service learning activities may be needed to sustain attitude change toward older adults. PMID:21964953

  10. Cognitive-Behavioral Treatment of Insomnia and Depression in Adolescents: A Pilot Randomized Trial

    PubMed Central

    Clarke, Greg; McGlinchey, Eleanor L.; Hein, Kerrie; Gullion, Christina M.; Dickerson, John F.; Leo, Michael C.; Harvey, Allison G.

    2015-01-01

    We tested whether augmenting conventional depression treatment in youth by treating sleep issues with cognitive behavioral therapy for insomnia (CBT-I) improved depression outcomes. We randomized youth 12–20 years of age to 10 weekly sessions of a sleep hygiene control condition (SH) combined with CBT for depression (CBT-D) (n=20), or an experimental condition consisting of CBT-I combined with CBT-D (n=21). We assessed outcomes through 26 weeks of follow-up and found medium-large effects favoring the experimental CBT-I arm on some sleep outcomes (actigraphy total sleep time and Insomnia Severity Index “caseness”) and depression outcomes (higher percentage recovered, faster time to recovery), but little effect on other measures. Total sleep time improved by 99 minutes from baseline to week 12 in the CBT-I arm, but not in the SH arm. In addition, our pilot yielded important products to facilitate future studies: the youth-adapted CBT-I program; the study protocol; estimates of recruitment, retention, and attrition; and performance and parameters of candidate outcome measures. PMID:25917009

  11. Expanding the limits of bibliotherapy for panic disorder: randomized trial of self-help without support but with a clear deadline.

    PubMed

    Nordin, Sara; Carlbring, Per; Cuijpers, Pim; Andersson, Gerhard

    2010-09-01

    Cognitive behavioral bibliotherapy for panic disorder has been found to be less effective without therapist support. In this study, participants were randomized to either unassisted bibliotherapy (n=20) with a scheduled follow-up telephone interview or to a waiting list control group (n=19). Following a structured psychiatric interview, participants in the treatment group were sent a self-help book consisting of 10 chapters based on cognitive behavioral strategies for the treatment of panic disorder. No therapist contact of any kind was provided during the treatment phase, which lasted for 10 weeks. Results showed that the treatment group had, in comparison to the control group, improved on all outcome measures at posttreatment and at 3-month follow-up. The tentative conclusion drawn from these results is that pure bibliotherapy with a clear deadline can be effective for people suffering from panic disorder with or without agoraphobia. PMID:20569776

  12. Percolation on correlated random networks

    NASA Astrophysics Data System (ADS)

    Agliari, E.; Cioli, C.; Guadagnini, E.

    2011-09-01

    We consider a class of random, weighted networks, obtained through a redefinition of patterns in an Hopfield-like model, and, by performing percolation processes, we get information about topology and resilience properties of the networks themselves. Given the weighted nature of the graphs, different kinds of bond percolation can be studied: stochastic (deleting links randomly) and deterministic (deleting links based on rank weights), each mimicking a different physical process. The evolution of the network is accordingly different, as evidenced by the behavior of the largest component size and of the distribution of cluster sizes. In particular, we can derive that weak ties are crucial in order to maintain the graph connected and that, when they are the most prone to failure, the giant component typically shrinks without abruptly breaking apart; these results have been recently evidenced in several kinds of social networks.

  13. The weighted random graph model

    NASA Astrophysics Data System (ADS)

    Garlaschelli, Diego

    2009-07-01

    We introduce the weighted random graph (WRG) model, which represents the weighted counterpart of the Erdos-Renyi random graph and provides fundamental insights into more complicated weighted networks. We find analytically that the WRG is characterized by a geometric weight distribution, a binomial degree distribution and a negative binomial strength distribution. We also characterize exactly the percolation phase transitions associated with edge removal and with the appearance of weighted subgraphs of any order and intensity. We find that even this completely null model displays a percolation behaviour similar to what is observed in real weighted networks, implying that edge removal cannot be used to detect community structure empirically. By contrast, the analysis of clustering successfully reveals different patterns between the WRG and real networks.

  14. Optimal randomized scheduling by replacement

    SciTech Connect

    Saias, I.

    1996-05-01

    In the replacement scheduling problem, a system is composed of n processors drawn from a pool of p. The processors can become faulty while in operation and faulty processors never recover. A report is issued whenever a fault occurs. This report states only the existence of a fault but does not indicate its location. Based on this report, the scheduler can reconfigure the system and choose another set of n processors. The system operates satisfactorily as long as, upon report of a fault, the scheduler chooses n non-faulty processors. We provide a randomized protocol maximizing the expected number of faults the system can sustain before the occurrence of a crash. The optimality of the protocol is established by considering a closely related dual optimization problem. The game-theoretic technical difficulties that we solve in this paper are very general and encountered whenever proving the optimality of a randomized algorithm in parallel and distributed computation.

  15. Random errors in egocentric networks.

    PubMed

    Almquist, Zack W

    2012-10-01

    The systematic errors that are induced by a combination of human memory limitations and common survey design and implementation have long been studied in the context of egocentric networks. Despite this, little if any work exists in the area of random error analysis on these same networks; this paper offers a perspective on the effects of random errors on egonet analysis, as well as the effects of using egonet measures as independent predictors in linear models. We explore the effects of false-positive and false-negative error in egocentric networks on both standard network measures and on linear models through simulation analysis on a ground truth egocentric network sample based on facebook-friendships. Results show that 5-20% error rates, which are consistent with error rates known to occur in ego network data, can cause serious misestimation of network properties and regression parameters. PMID:23878412

  16. Random errors in egocentric networks

    PubMed Central

    Almquist, Zack W.

    2013-01-01

    The systematic errors that are induced by a combination of human memory limitations and common survey design and implementation have long been studied in the context of egocentric networks. Despite this, little if any work exists in the area of random error analysis on these same networks; this paper offers a perspective on the effects of random errors on egonet analysis, as well as the effects of using egonet measures as independent predictors in linear models. We explore the effects of false-positive and false-negative error in egocentric networks on both standard network measures and on linear models through simulation analysis on a ground truth egocentric network sample based on facebook-friendships. Results show that 5–20% error rates, which are consistent with error rates known to occur in ego network data, can cause serious misestimation of network properties and regression parameters. PMID:23878412

  17. Image segmentation using random features

    NASA Astrophysics Data System (ADS)

    Bull, Geoff; Gao, Junbin; Antolovich, Michael

    2014-01-01

    This paper presents a novel algorithm for selecting random features via compressed sensing to improve the performance of Normalized Cuts in image segmentation. Normalized Cuts is a clustering algorithm that has been widely applied to segmenting images, using features such as brightness, intervening contours and Gabor filter responses. Some drawbacks of Normalized Cuts are that computation times and memory usage can be excessive, and the obtained segmentations are often poor. This paper addresses the need to improve the processing time of Normalized Cuts while improving the segmentations. A significant proportion of the time in calculating Normalized Cuts is spent computing an affinity matrix. A new algorithm has been developed that selects random features using compressed sensing techniques to reduce the computation needed for the affinity matrix. The new algorithm, when compared to the standard implementation of Normalized Cuts for segmenting images from the BSDS500, produces better segmentations in significantly less time.

  18. Random modelling of contagious diseases.

    PubMed

    Demongeot, J; Hansen, O; Hessami, H; Jannot, A S; Mintsa, J; Rachdi, M; Taramasco, C

    2013-03-01

    Modelling contagious diseases needs to include a mechanistic knowledge about contacts between hosts and pathogens as specific as possible, e.g., by incorporating in the model information about social networks through which the disease spreads. The unknown part concerning the contact mechanism can be modelled using a stochastic approach. For that purpose, we revisit SIR models by introducing first a microscopic stochastic version of the contacts between individuals of different populations (namely Susceptible, Infective and Recovering), then by adding a random perturbation in the vicinity of the endemic fixed point of the SIR model and eventually by introducing the definition of various types of random social networks. We propose as example of application to contagious diseases the HIV, and we show that a micro-simulation of individual based modelling (IBM) type can reproduce the current stable incidence of the HIV epidemic in a population of HIV-positive men having sex with men (MSM). PMID:23525763

  19. Correlated randomness and switching phenomena

    NASA Astrophysics Data System (ADS)

    Stanley, H. E.; Buldyrev, S. V.; Franzese, G.; Havlin, S.; Mallamace, F.; Kumar, P.; Plerou, V.; Preis, T.

    2010-08-01

    One challenge of biology, medicine, and economics is that the systems treated by these serious scientific disciplines have no perfect metronome in time and no perfect spatial architecture-crystalline or otherwise. Nonetheless, as if by magic, out of nothing but randomness one finds remarkably fine-tuned processes in time and remarkably fine-tuned structures in space. Further, many of these processes and structures have the remarkable feature of “switching” from one behavior to another as if by magic. The past century has, philosophically, been concerned with placing aside the human tendency to see the universe as a fine-tuned machine. Here we will address the challenge of uncovering how, through randomness (albeit, as we shall see, strongly correlated randomness), one can arrive at some of the many spatial and temporal patterns in biology, medicine, and economics and even begin to characterize the switching phenomena that enables a system to pass from one state to another. Inspired by principles developed by A. Nihat Berker and scores of other statistical physicists in recent years, we discuss some applications of correlated randomness to understand switching phenomena in various fields. Specifically, we present evidence from experiments and from computer simulations supporting the hypothesis that water’s anomalies are related to a switching point (which is not unlike the “tipping point” immortalized by Malcolm Gladwell), and that the bubbles in economic phenomena that occur on all scales are not “outliers” (another Gladwell immortalization). Though more speculative, we support the idea of disease as arising from some kind of yet-to-be-understood complex switching phenomenon, by discussing data on selected examples, including heart disease and Alzheimer disease.

  20. Random drift and culture change.

    PubMed Central

    Bentley, R. Alexander; Hahn, Matthew W.; Shennan, Stephen J.

    2004-01-01

    We show that the frequency distributions of cultural variants, in three different real-world examples--first names, archaeological pottery and applications for technology patents--follow power laws that can be explained by a simple model of random drift. We conclude that cultural and economic choices often reflect a decision process that is value-neutral; this result has far-reaching testable implications for social-science research. PMID:15306315

  1. Randomized gap and amplitude estimation

    NASA Astrophysics Data System (ADS)

    Zintchenko, Ilia; Wiebe, Nathan

    2016-06-01

    We provide a method for estimating spectral gaps in low-dimensional systems. Unlike traditional phase estimation, our approach does not require ancillary qubits nor does it require well-characterized gates. Instead, it only requires the ability to perform approximate Haar random unitary operations, applying the unitary whose eigenspectrum is sought and performing measurements in the computational basis. We discuss application of these ideas to in-place amplitude estimation and quantum device calibration.

  2. Random drift and culture change.

    PubMed

    Bentley, R Alexander; Hahn, Matthew W; Shennan, Stephen J

    2004-07-22

    We show that the frequency distributions of cultural variants, in three different real-world examples--first names, archaeological pottery and applications for technology patents--follow power laws that can be explained by a simple model of random drift. We conclude that cultural and economic choices often reflect a decision process that is value-neutral; this result has far-reaching testable implications for social-science research. PMID:15306315

  3. Decoupling with Random Quantum Circuits

    NASA Astrophysics Data System (ADS)

    Brown, Winton; Fawzi, Omar

    2015-12-01

    Decoupling has become a central concept in quantum information theory, with applications including proving coding theorems, randomness extraction and the study of conditions for reaching thermal equilibrium. However, our understanding of the dynamics that lead to decoupling is limited. In fact, the only families of transformations that are known to lead to decoupling are (approximate) unitary two-designs, i.e., measures over the unitary group that behave like the Haar measure as far as the first two moments are concerned. Such families include for example random quantum circuits with O( n 2) gates, where n is the number of qubits in the system under consideration. In fact, all known constructions of decoupling circuits use Ω( n 2) gates. Here, we prove that random quantum circuits with O( n log2 n) gates satisfy an essentially optimal decoupling theorem. In addition, these circuits can be implemented in depth O(log3 n). This proves that decoupling can happen in a time that scales polylogarithmically in the number of particles in the system, provided all the particles are allowed to interact. Our proof does not proceed by showing that such circuits are approximate two-designs in the usual sense, but rather we directly analyze the decoupling property.

  4. Resolution analysis by random probing

    NASA Astrophysics Data System (ADS)

    Simutė, S.; Fichtner, A.; van Leeuwen, T.

    2015-12-01

    We develop and apply methods for resolution analysis in tomography, based on stochastic probing of the Hessian or resolution operators. Key properties of our methods are (i) low algorithmic complexity and easy implementation, (ii) applicability to any tomographic technique, including full-waveform inversion and linearized ray tomography, (iii) applicability in any spatial dimension and to inversions with a large number of model parameters, (iv) low computational costs that are mostly a fraction of those required for synthetic recovery tests, and (v) the ability to quantify both spatial resolution and inter-parameter trade-offs. Using synthetic full-waveform inversions as benchmarks, we demonstrate that auto-correlations of random-model applications to the Hessian yield various resolution measures, including direction- and position-dependent resolution lengths, and the strength of inter-parameter mappings. We observe that the required number of random test models is around 5 in one, two and three dimensions. This means that the proposed resolution analyses are not only more meaningful than recovery tests but also computationally less expensive. We demonstrate the applicability of our method in 3D real-data full-waveform inversions for the western Mediterranean and Japan. In addition to tomographic problems, resolution analysis by random probing may be used in other inverse methods that constrain continuously distributed properties, including electromagnetic and potential-field inversions, as well as recently emerging geodynamic data assimilation.

  5. Resolution analysis by random probing

    NASA Astrophysics Data System (ADS)

    Fichtner, Andreas; Leeuwen, Tristan van

    2015-08-01

    We develop and apply methods for resolution analysis in tomography, based on stochastic probing of the Hessian or resolution operators. Key properties of our methods are (i) low algorithmic complexity and easy implementation, (ii) applicability to any tomographic technique, including full-waveform inversion and linearized ray tomography, (iii) applicability in any spatial dimension and to inversions with a large number of model parameters, (iv) low computational costs that are mostly a fraction of those required for synthetic recovery tests, and (v) the ability to quantify both spatial resolution and interparameter trade-offs. Using synthetic full-waveform inversions as benchmarks, we demonstrate that autocorrelations of random-model applications to the Hessian yield various resolution measures, including direction- and position-dependent resolution lengths and the strength of interparameter mappings. We observe that the required number of random test models is around five in one, two, and three dimensions. This means that the proposed resolution analyses are not only more meaningful than recovery tests but also computationally less expensive. We demonstrate the applicability of our method in a 3-D real-data full-waveform inversion for the western Mediterranean. In addition to tomographic problems, resolution analysis by random probing may be used in other inverse methods that constrain continuously distributed properties, including electromagnetic and potential-field inversions, as well as recently emerging geodynamic data assimilation.

  6. Topological insulators in random potentials

    NASA Astrophysics Data System (ADS)

    Pieper, Andreas; Fehske, Holger

    2016-01-01

    We investigate the effects of magnetic and nonmagnetic impurities on the two-dimensional surface states of three-dimensional topological insulators (TIs). Modeling weak and strong TIs using a generic four-band Hamiltonian, which allows for a breaking of inversion and time-reversal symmetries and takes into account random local potentials as well as the Zeeman and orbital effects of external magnetic fields, we compute the local density of states, the single-particle spectral function, and the conductance for a (contacted) slab geometry by numerically exact techniques based on kernel polynomial expansion and Green's function approaches. We show that bulk disorder refills the surface-state Dirac gap induced by a homogeneous magnetic field with states, whereas orbital (Peierls-phase) disorder preserves the gap feature. The former effect is more pronounced in weak TIs than in strong TIs. At moderate randomness, disorder-induced conducting channels appear in the surface layer, promoting diffusive metallicity. Random Zeeman fields rapidly destroy any conducting surface states. Imprinting quantum dots on a TI's surface, we demonstrate that carrier transport can be easily tuned by varying the gate voltage, even to the point where quasibound dot states may appear.

  7. Approximating random quantum optimization problems

    NASA Astrophysics Data System (ADS)

    Hsu, B.; Laumann, C. R.; Läuchli, A. M.; Moessner, R.; Sondhi, S. L.

    2013-06-01

    We report a cluster of results regarding the difficulty of finding approximate ground states to typical instances of the quantum satisfiability problem k-body quantum satisfiability (k-QSAT) on large random graphs. As an approximation strategy, we optimize the solution space over “classical” product states, which in turn introduces a novel autonomous classical optimization problem, PSAT, over a space of continuous degrees of freedom rather than discrete bits. Our central results are (i) the derivation of a set of bounds and approximations in various limits of the problem, several of which we believe may be amenable to a rigorous treatment; (ii) a demonstration that an approximation based on a greedy algorithm borrowed from the study of frustrated magnetism performs well over a wide range in parameter space, and its performance reflects the structure of the solution space of random k-QSAT. Simulated annealing exhibits metastability in similar “hard” regions of parameter space; and (iii) a generalization of belief propagation algorithms introduced for classical problems to the case of continuous spins. This yields both approximate solutions, as well as insights into the free energy “landscape” of the approximation problem, including a so-called dynamical transition near the satisfiability threshold. Taken together, these results allow us to elucidate the phase diagram of random k-QSAT in a two-dimensional energy-density-clause-density space.

  8. The effect of low glycemic index diet on body weight status and blood pressure in overweight adolescent girls: a randomized clinical trial

    PubMed Central

    Rouhani, Mohammad Hossein; Kelishadi, Roya; Hashemipour, Mahin; Esmaillzadeh, Ahmad

    2013-01-01

    Although several studies have assessed the influence of the glycemic index on body weight and blood pressure among adults, limited evidence exists for the pediatric age population. In the current study, we compared the effects of low glycemic index (LGI) diet to the healthy nutritional recommendation (HNR)-based diet on obesity and blood pressure among adolescent girls in pubertal ages. This 10-week parallel randomized clinical trial comprised of 50 overweight or obese and sexually mature girls less than 18 years of age years, who were randomly assigned to LGI or HNR-based diet. Macronutrient distribution was equivalently prescribed in both groups. Blood pressure, weight and waist circumference were measured at baseline and after intervention. Of the 50 participants, 41 subjects (include 82%) completed the study. The GI of the diet in the LGI group was 42.67 ± 0.067. A within-group analysis illustrated that in comparison to the baseline values, the body weight and body mass index (not waist circumference and blood pressure) decreased significantly after the intervention in both groups (P = 0.0001). The percent changes of the body weight status, waist circumference and blood pressure were compared between the two groups and the findings did not show any difference between the LGI diet consumers and those in the HNR group. In comparison to the HNR, LGI diet could not change the weight and blood pressure following a 10-week intervention. Further longitudinal studies with a long-term follow up should be conducted in this regard. PMID:24133618

  9. Changes in work affect in response to lunchtime walking in previously physically inactive employees: A randomized trial.

    PubMed

    Thøgersen-Ntoumani, C; Loughren, E A; Kinnafick, F-E; Taylor, I M; Duda, J L; Fox, K R

    2015-12-01

    Physical activity may regulate affective experiences at work, but controlled studies are needed and there has been a reliance on retrospective accounts of experience. The purpose of the present study was to examine the effect of lunchtime walks on momentary work affect at the individual and group levels. Physically inactive employees (N = 56; M age = 47.68; 92.86% female) from a large university in the UK were randomized to immediate treatment or delayed treatment (DT). The DT participants completed both a control and intervention period. During the intervention period, participants partook in three weekly 30-min lunchtime group-led walks for 10 weeks. They completed twice daily affective reports at work (morning and afternoon) using mobile phones on two randomly chosen days per week. Multilevel modeling was used to analyze the data. Lunchtime walks improved enthusiasm, relaxation, and nervousness at work, although the pattern of results differed depending on whether between-group or within-person analyses were conducted. The intervention was effective in changing some affective states and may have broader implications for public health and workplace performance. PMID:25559067

  10. Randomized clinical trial of multimodal physiotherapy treatment compared to overnight lidocaine ointment in women with provoked vestibulodynia: Design and methods.

    PubMed

    Morin, Mélanie; Dumoulin, Chantale; Bergeron, Sophie; Mayrand, Marie-Hélène; Khalifé, Samir; Waddell, Guy; Dubois, Marie-France

    2016-01-01

    Provoked vestibulodynia (PVD) is a highly prevalent and debilitating condition yet its management relies mainly on non-empirically validated interventions. Among the many causes of PVD, there is growing evidence that pelvic floor muscle (PFM) dysfunctions play an important role in its pathophysiology. Multimodal physiotherapy, which addresses these dysfunctions, is judged by experts to be highly effective and is recommended as a first-line treatment. However, the effectiveness of this promising intervention has been evaluated through only two small uncontrolled trials. The proposed bi-center, single-blind, parallel group, randomized controlled trial (RCT) aims to evaluate the efficacy of multimodal physiotherapy and compare it to a frequently used first-line treatment, topical overnight application of lidocaine, in women with PVD. A total of 212 women diagnosed with PVD according to a standardized protocol were eligible for the study and were randomly assigned to either multimodal physiotherapy or lidocaine treatment for 10weeks. The primary outcome measure is pain during intercourse (assessed with a numerical rating scale). Secondary measures include sexual function, pain quality, psychological factors (including pain catastrophizing, anxiety, depression and fear of pain), PFM morphology and function, and patients' global impression of change. Assessments are made at baseline, post-treatment and at the 6-month follow-up. This manuscript presents and discusses the rationale, design and methodology of the first RCT investigating physiotherapy in comparison to a commonly prescribed first-line treatment, overnight topical lidocaine, for women with PVD. PMID:26600287

  11. The impact of performance incentives on child health outcomes: results from a cluster randomized controlled trial in the Philippines.

    PubMed

    Peabody, John W; Shimkhada, Riti; Quimbo, Stella; Solon, Orville; Javier, Xylee; McCulloch, Charles

    2014-08-01

    Improving clinical performance using measurement and payment incentives, including pay for performance (or P4P), has, so far, shown modest to no benefit on patient outcomes. Our objective was to assess the impact of a P4P programme on paediatric health outcomes in the Philippines. We used data from the Quality Improvement Demonstration Study. In this study, the P4P intervention, introduced in 2004, was randomly assigned to 10 community district hospitals, which were matched to 10 control sites. At all sites, physician quality was measured using Clinical Performance Vignettes (CPVs) among randomly selected physicians every 6 months over a 36-month period. In the hospitals randomized to the P4P intervention, physicians received bonus payments if they met qualifying scores on the CPV. We measured health outcomes 4-10 weeks after hospital discharge among children 5 years of age and under who had been hospitalized for diarrhoea and pneumonia (the two most common illnesses affecting this age cohort) and had been under the care of physicians participating in the study. Health outcomes data collection was done at baseline/pre-intervention and 2 years post-intervention on the following post-discharge outcomes: (1) age-adjusted wasting, (2) C-reactive protein in blood, (3) haemoglobin level and (4) parental assessment of child's health using general self-reported health (GSRH) measure. To evaluate changes in health outcomes in the control vs intervention sites over time (baseline vs post-intervention), we used a difference-in-difference logistic regression analysis, controlling for potential confounders. We found an improvement of 7 and 9 percentage points in GSRH and wasting over time (post-intervention vs baseline) in the intervention sites relative to the control sites (P ≤ 0.001). The results from this randomized social experiment indicate that the introduction of a performance-based incentive programme, which included measurement and feedback, led to improvements in

  12. Hypnosis as a treatment of chronic widespread pain in general practice: A randomized controlled pilot trial

    PubMed Central

    Grøndahl, Jan Robert; Rosvold, Elin Olaug

    2008-01-01

    Background Hypnosis treatment in general practice is a rather new concept. This pilot study was performed to evaluate the effect of a standardized hypnosis treatment used in general practice for patients with chronic widespread pain (CWP). Methods The study was designed as a randomized control group-controlled study. Sixteen patients were randomized into a treatment group or a control group, each constituting eight patients. Seven patients in the treatment group completed the schedule. After the control period, five of the patients in the control group also received treatment, making a total of 12 patients having completed the treatment sessions. The intervention group went through a standardized hypnosis treatment with ten consecutive therapeutic sessions once a week, each lasting for about 30 minutes, focusing on ego-strengthening, relaxation, releasing muscular tension and increasing self-efficacy. A questionnaire was developed in order to calibrate the symptoms before and after the 10 weeks period, and the results were interpolated into a scale from 0 to 100, increasing numbers representing increasing suffering. Data were analyzed by means of T-tests. Results The treatment group improved from their symptoms, (change from 62.5 to 55.4), while the control group deteriorated, (change from 37.2 to 45.1), (p = 0,045). The 12 patients who completed the treatment showed a mean improvement from 51.5 to 41.6. (p = 0,046). One year later the corresponding result was 41.3, indicating a persisting improvement. Conclusion The study indicates that hypnosis treatment may have a positive effect on pain and quality of life for patients with chronic muscular pain. Considering the limited number of patients, more studies should be conducted to confirm the results. Trial Registration The study was registered in ClinicalTrials.gov and released 27.08.07 Reg nr NCT00521807 Approval Number: 05032001. PMID:18801190

  13. Randomized Controlled Trial of Therapeutic Horseback Riding in Children and Adolescents With Autism Spectrum Disorder

    PubMed Central

    Gabriels, Robin L.; Pan, Zhaoxing; Dechant, Briar; Agnew, John A.; Brim, Natalie; Mesibov, Gary

    2015-01-01

    Objective This study expands previous equine-assisted intervention research by evaluating the effectiveness of therapeutic horseback riding (THR) on self-regulation, socialization, communication, adaptive, and motor behaviors in children with autism spectrum disorder (ASD). Method Participants with ASD (ages 6–16 years; N=127) were stratified by nonverbal IQ standard scores (≤ 85 or > 85) and randomized to one of two groups for 10 weeks: THR intervention or a barn activity (BA) control group without horses that employed similar methods. The fidelity of the THR intervention was monitored. Participants were evaluated within one month pre- and post-intervention by raters blind to intervention conditions and unblinded caregiver questionnaires. During the intervention, caregivers rated participants’ behaviors weekly. Results Intent-to-treat analysis conducted on the 116 participants who completed a baseline assessment (THR n = 58; BA control n = 58) revealed significant improvements in the THR group compared to the control on measures of irritability (primary outcome) (p=.002; effect size [ES]=.50) and hyperactivity (p=.001; ES=0.53), beginning by week five of the intervention. Significant improvements in the THR group were also observed on a measure of social cognition (p=.05, ES=.41) and social communication (p=.003; ES =.63), along with the total number of words (p=.01; ES=.54) and new words (p=.01; ES=.54) spoken during a standardized language sample. Sensitivity analyses adjusting for age, IQ, and per-protocol analyses produced consistent results. Conclusion This is the first large-scale randomized, controlled trial demonstrating efficacy of THR for the ASD population, and findings are consistent with previous equine-assisted intervention studies. Clinical trial registration information Trial of Therapeutic Horseback Riding in Children and Adolescents With Autism Spectrum Disorder; http://clinicaltrials.gov/; NCT02301195. PMID:26088658

  14. Smartphone Mobile Application Delivering Personalized, Real-Time Sun Protection Advice: A Randomized Clinical Trial

    PubMed Central

    Buller, David B.; Berwick, Marianne; Lantz, Kathy; Buller, Mary Klein; Shane, James; Kane, Ilima; Liu, Xia

    2014-01-01

    Importance Mobile smart phones are rapidly emerging as an effective means of communicating with many Americans. Using mobile applications, they can access remote databases, track time and location, and integrate user input to provide tailored health information. Objective A smart phone mobile application providing personalized, real-time sun protection advice was evaluated in a randomized trial. Design The trial was conducted in 2012 and had a randomized pretest-posttest controlled design with a 10-week follow-up. Setting Data was collected from a nationwide population-based survey panel. Participants The trial enrolled a sample of n=604 non-Hispanic and Hispanic adults from the Knowledge Panel® aged 18 or older who owned an Android smart phone. Intervention The mobile application provided advice on sun protection (i.e., protection practices and risk of sunburn) and alerts (to apply/reapply sunscreen and get out of the sun), hourly UV Index, and vitamin D production based on the forecast UV Index, phone's time and location, and user input. Main Outcomes and Measures Percent of days using sun protection and time spent outdoors (days and minutes) in the midday sun and number of sunburns in the past 3 months were collected. Results Individuals in the treatment group reported more shade use but less sunscreen use than controls. Those who used the mobile app reported spending less time in the sun and using all protection behaviors combined more. Conclusions and Relevance The mobile application improved some sun protection. Use of the mobile application was lower than expected but associated with increased sun protection. Providing personalized advice when and where people are in the sun may help reduce sun exposure. PMID:25629710

  15. Brief Cognitive-Behavioral and Relaxation Training Interventions for Breast Cancer: A Randomized Controlled Trial

    PubMed Central

    Gudenkauf, Lisa M.; Antoni, Michael H.; Stagl, Jamie M.; Lechner, Suzanne C.; Jutagir, Devika R.; Bouchard, Laura C.; Blomberg, Bonnie B.; Glück, Stefan; Derhagopian, Robert P.; Giron, Gladys L.; Avisar, Eli; Torres-Salichs, Manuel A.; Carver, Charles S.

    2015-01-01

    Objective Women with breast cancer (BCa) report elevated distress post-surgery. Group-based cognitive-behavioral stress management (CBSM) following surgery improves psychological adaptation, though its key mechanisms remain speculative. This randomized controlled dismantling trial compared two interventions featuring elements thought to drive CBSM effects: a 5-week Cognitive-Behavioral Training (CBT) and 5-week Relaxation Training (RT) vs. a 5-week Health Education (HE) control group. Method Women with stage 0-III BCa (N = 183) were randomized to CBT, RT, or HE condition 2–10 weeks post-surgery. Psychosocial measures were collected at baseline (T1) and post-intervention (T2). Repeated-measures ANOVAs tested whether CBT and RT treatments improved primary measures of psychological adaptation and secondary measures of stress management resource perceptions from pre- to post-intervention relative to HE. Results Both CBT and RT groups reported reduced depressive affect. The CBT group reported improved emotional well-being/quality of life and less cancer-specific thought intrusions. The RT group reported improvements on illness-related social disruption. Regarding stress management resources, the CBT group reported increased reliability of social support networks, while the RT group reported increased confidence in relaxation skills. Psychological adaptation and stress management resource constructs were unchanged in the HE control group. Conclusions Non-metastatic breast cancer patients participating in two forms of brief, 5-week group-based stress management intervention after surgery showed improvements in psychological adaptation and stress management resources compared to an attention-matched control group. Findings provide preliminary support suggesting that using brief group-based stress management interventions may promote adaptation among non-metastatic breast cancer patients. PMID:25939017

  16. Localization for random and quasiperiodic potentials

    NASA Astrophysics Data System (ADS)

    Spencer, Thomas

    1988-06-01

    A survey is made of some recent mathematical results and techniques for Schrödinger operators with random and quasiperiodic potentials. A new proof of localization for random potentials, established in collaboration with H. von Dreifus, is sketched.

  17. Self-correcting random number generator

    DOEpatents

    Humble, Travis S.; Pooser, Raphael C.

    2016-09-06

    A system and method for generating random numbers. The system may include a random number generator (RNG), such as a quantum random number generator (QRNG) configured to self-correct or adapt in order to substantially achieve randomness from the output of the RNG. By adapting, the RNG may generate a random number that may be considered random regardless of whether the random number itself is tested as such. As an example, the RNG may include components to monitor one or more characteristics of the RNG during operation, and may use the monitored characteristics as a basis for adapting, or self-correcting, to provide a random number according to one or more performance criteria.

  18. Generation of pseudo-random numbers

    NASA Technical Reports Server (NTRS)

    Howell, L. W.; Rheinfurth, M. H.

    1982-01-01

    Practical methods for generating acceptable random numbers from a variety of probability distributions which are frequently encountered in engineering applications are described. The speed, accuracy, and guarantee of statistical randomness of the various methods are discussed.

  19. High speed optical quantum random number generation.

    PubMed

    Fürst, Martin; Weier, Henning; Nauerth, Sebastian; Marangon, Davide G; Kurtsiefer, Christian; Weinfurter, Harald

    2010-06-01

    We present a fully integrated, ready-for-use quantum random number generator (QRNG) whose stochastic model is based on the randomness of detecting single photons in attenuated light. We show that often annoying deadtime effects associated with photomultiplier tubes (PMT) can be utilized to avoid postprocessing for bias or correlations. The random numbers directly delivered to a PC, generated at a rate of up to 50 Mbit/s, clearly pass all tests relevant for (physical) random number generators. PMID:20588431

  20. The HEART Pathway Randomized Trial

    PubMed Central

    Mahler, Simon A.; Riley, Robert F.; Hiestand, Brian C.; Russell, Gregory B.; Hoekstra, James W.; Lefebvre, Cedric W.; Nicks, Bret A.; Cline, David M.; Askew, Kim L.; Elliott, Stephanie B.; Herrington, David M.; Burke, Gregory L.; Miller, Chadwick D.

    2015-01-01

    Background The HEART Pathway is a decision aid designed to identify emergency department patients with acute chest pain for early discharge. No randomized trials have compared the HEART Pathway with usual care. Methods and Results Adult emergency department patients with symptoms related to acute coronary syndrome without ST-elevation on ECG (n=282) were randomized to the HEART Pathway or usual care. In the HEART Pathway arm, emergency department providers used the HEART score, a validated decision aid, and troponin measures at 0 and 3 hours to identify patients for early discharge. Usual care was based on American College of Cardiology/American Heart Association guidelines. The primary outcome, objective cardiac testing (stress testing or angiography), and secondary outcomes, index length of stay, early discharge, and major adverse cardiac events (death, myocardial infarction, or coronary revascularization), were assessed at 30 days by phone interview and record review. Participants had a mean age of 53 years, 16% had previous myocardial infarction, and 6% (95% confidence interval, 3.6%–9.5%) had major adverse cardiac events within 30 days of randomization. Compared with usual care, use of the HEART Pathway decreased objective cardiac testing at 30 days by 12.1% (68.8% versus 56.7%; P=0.048) and length of stay by 12 hours (9.9 versus 21.9 hours; P=0.013) and increased early discharges by 21.3% (39.7% versus 18.4%; P<0.001). No patients identified for early discharge had major adverse cardiac events within 30 days. Conclusions The HEART Pathway reduces objective cardiac testing during 30 days, shortens length of stay, and increases early discharges. These important efficiency gains occurred without any patients identified for early discharge suffering MACE at 30 days. PMID:25737484

  1. Random Matrix Theory and Econophysics

    NASA Astrophysics Data System (ADS)

    Rosenow, Bernd

    2000-03-01

    Random Matrix Theory (RMT) [1] is used in many branches of physics as a ``zero information hypothesis''. It describes generic behavior of different classes of systems, while deviations from its universal predictions allow to identify system specific properties. We use methods of RMT to analyze the cross-correlation matrix C of stock price changes [2] of the largest 1000 US companies. In addition to its scientific interest, the study of correlations between the returns of different stocks is also of practical relevance in quantifying the risk of a given stock portfolio. We find [3,4] that the statistics of most of the eigenvalues of the spectrum of C agree with the predictions of RMT, while there are deviations for some of the largest eigenvalues. We interpret these deviations as a system specific property, e.g. containing genuine information about correlations in the stock market. We demonstrate that C shares universal properties with the Gaussian orthogonal ensemble of random matrices. Furthermore, we analyze the eigenvectors of C through their inverse participation ratio and find eigenvectors with large ratios at both edges of the eigenvalue spectrum - a situation reminiscent of localization theory results. This work was done in collaboration with V. Plerou, P. Gopikrishnan, T. Guhr, L.A.N. Amaral, and H.E Stanley and is related to recent work of Laloux et al.. 1. T. Guhr, A. Müller Groeling, and H.A. Weidenmüller, ``Random Matrix Theories in Quantum Physics: Common Concepts'', Phys. Rep. 299, 190 (1998). 2. See, e.g. R.N. Mantegna and H.E. Stanley, Econophysics: Correlations and Complexity in Finance (Cambridge University Press, Cambridge, England, 1999). 3. V. Plerou, P. Gopikrishnan, B. Rosenow, L.A.N. Amaral, and H.E. Stanley, ``Universal and Nonuniversal Properties of Cross Correlations in Financial Time Series'', Phys. Rev. Lett. 83, 1471 (1999). 4. V. Plerou, P. Gopikrishnan, T. Guhr, B. Rosenow, L.A.N. Amaral, and H.E. Stanley, ``Random Matrix Theory

  2. Random bearings and their stability.

    PubMed

    Mahmoodi Baram, Reza; Herrmann, Hans J

    2005-11-25

    Self-similar space-filling bearings have been proposed some time ago as models for the motion of tectonic plates and appearance of seismic gaps. These models have two features which, however, seem unrealistic, namely, high symmetry in the arrangement of the particles, and lack of a lower cutoff in the size of the particles. In this work, an algorithm for generating random bearings in both two and three dimensions is presented. Introducing a lower cutoff for the sizes of the particles, the instabilities of the bearing under an external force such as gravity, are studied. PMID:16384225

  3. Quantum random walks without walking

    SciTech Connect

    Manouchehri, K.; Wang, J. B.

    2009-12-15

    Quantum random walks have received much interest due to their nonintuitive dynamics, which may hold the key to a new generation of quantum algorithms. What remains a major challenge is a physical realization that is experimentally viable and not limited to special connectivity criteria. We present a scheme for walking on arbitrarily complex graphs, which can be realized using a variety of quantum systems such as a Bose-Einstein condensate trapped inside an optical lattice. This scheme is particularly elegant since the walker is not required to physically step between the nodes; only flipping coins is sufficient.

  4. Randomized selection on the GPU

    SciTech Connect

    Monroe, Laura Marie; Wendelberger, Joanne R; Michalak, Sarah E

    2011-01-13

    We implement here a fast and memory-sparing probabilistic top N selection algorithm on the GPU. To our knowledge, this is the first direct selection in the literature for the GPU. The algorithm proceeds via a probabilistic-guess-and-chcck process searching for the Nth element. It always gives a correct result and always terminates. The use of randomization reduces the amount of data that needs heavy processing, and so reduces the average time required for the algorithm. Probabilistic Las Vegas algorithms of this kind are a form of stochastic optimization and can be well suited to more general parallel processors with limited amounts of fast memory.

  5. RANDOM FORESTS FOR PHOTOMETRIC REDSHIFTS

    SciTech Connect

    Carliles, Samuel; Szalay, Alexander S.; Budavari, Tamas; Heinis, Sebastien; Priebe, Carey

    2010-03-20

    The main challenge today in photometric redshift estimation is not in the accuracy but in understanding the uncertainties. We introduce an empirical method based on Random Forests to address these issues. The training algorithm builds a set of optimal decision trees on subsets of the available spectroscopic sample, which provide independent constraints on the redshift of each galaxy. The combined forest estimates have intriguing statistical properties, notable among which are Gaussian errors. We demonstrate the power of our approach on multi-color measurements of the Sloan Digital Sky Survey.

  6. Quantum random flip-flop and its applications in random frequency synthesis and true random number generation.

    PubMed

    Stipčević, Mario

    2016-03-01

    In this work, a new type of elementary logic circuit, named random flip-flop (RFF), is proposed, experimentally realized, and studied. Unlike conventional Boolean logic circuits whose action is deterministic and highly reproducible, the action of a RFF is intentionally made maximally unpredictable and, in the proposed realization, derived from a fundamentally random process of emission and detection of light quanta. We demonstrate novel applications of RFF in randomness preserving frequency division, random frequency synthesis, and random number generation. Possible usages of these applications in the information and communication technology, cryptographic hardware, and testing equipment are discussed. PMID:27036825

  7. Quantum random flip-flop and its applications in random frequency synthesis and true random number generation

    NASA Astrophysics Data System (ADS)

    Stipčević, Mario

    2016-03-01

    In this work, a new type of elementary logic circuit, named random flip-flop (RFF), is proposed, experimentally realized, and studied. Unlike conventional Boolean logic circuits whose action is deterministic and highly reproducible, the action of a RFF is intentionally made maximally unpredictable and, in the proposed realization, derived from a fundamentally random process of emission and detection of light quanta. We demonstrate novel applications of RFF in randomness preserving frequency division, random frequency synthesis, and random number generation. Possible usages of these applications in the information and communication technology, cryptographic hardware, and testing equipment are discussed.

  8. Source-Independent Quantum Random Number Generation

    NASA Astrophysics Data System (ADS)

    Cao, Zhu; Zhou, Hongyi; Yuan, Xiao; Ma, Xiongfeng

    2016-01-01

    Quantum random number generators can provide genuine randomness by appealing to the fundamental principles of quantum mechanics. In general, a physical generator contains two parts—a randomness source and its readout. The source is essential to the quality of the resulting random numbers; hence, it needs to be carefully calibrated and modeled to achieve information-theoretical provable randomness. However, in practice, the source is a complicated physical system, such as a light source or an atomic ensemble, and any deviations in the real-life implementation from the theoretical model may affect the randomness of the output. To close this gap, we propose a source-independent scheme for quantum random number generation in which output randomness can be certified, even when the source is uncharacterized and untrusted. In our randomness analysis, we make no assumptions about the dimension of the source. For instance, multiphoton emissions are allowed in optical implementations. Our analysis takes into account the finite-key effect with the composable security definition. In the limit of large data size, the length of the input random seed is exponentially small compared to that of the output random bit. In addition, by modifying a quantum key distribution system, we experimentally demonstrate our scheme and achieve a randomness generation rate of over 5 ×103 bit /s .

  9. Randomness in Sequence Evolution Increases over Time.

    PubMed

    Wang, Guangyu; Sun, Shixiang; Zhang, Zhang

    2016-01-01

    The second law of thermodynamics states that entropy, as a measure of randomness in a system, increases over time. Although studies have investigated biological sequence randomness from different aspects, it remains unknown whether sequence randomness changes over time and whether this change consists with the second law of thermodynamics. To capture the dynamics of randomness in molecular sequence evolution, here we detect sequence randomness based on a collection of eight statistical random tests and investigate the randomness variation of coding sequences with an application to Escherichia coli. Given that core/essential genes are more ancient than specific/non-essential genes, our results clearly show that core/essential genes are more random than specific/non-essential genes and accordingly indicate that sequence randomness indeed increases over time, consistent well with the second law of thermodynamics. We further find that an increase in sequence randomness leads to increasing randomness of GC content and longer sequence length. Taken together, our study presents an important finding, for the first time, that sequence randomness increases over time, which may provide profound insights for unveiling the underlying mechanisms of molecular sequence evolution. PMID:27224236

  10. 49 CFR 655.45 - Random testing.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... is notified of selection for random drug or random alcohol testing proceed to the test site..., DEPARTMENT OF TRANSPORTATION PREVENTION OF ALCOHOL MISUSE AND PROHIBITED DRUG USE IN TRANSIT OPERATIONS Types... section, the minimum annual percentage rate for random drug testing shall be 50 percent of...

  11. Randomness in Sequence Evolution Increases over Time

    PubMed Central

    Wang, Guangyu; Sun, Shixiang; Zhang, Zhang

    2016-01-01

    The second law of thermodynamics states that entropy, as a measure of randomness in a system, increases over time. Although studies have investigated biological sequence randomness from different aspects, it remains unknown whether sequence randomness changes over time and whether this change consists with the second law of thermodynamics. To capture the dynamics of randomness in molecular sequence evolution, here we detect sequence randomness based on a collection of eight statistical random tests and investigate the randomness variation of coding sequences with an application to Escherichia coli. Given that core/essential genes are more ancient than specific/non-essential genes, our results clearly show that core/essential genes are more random than specific/non-essential genes and accordingly indicate that sequence randomness indeed increases over time, consistent well with the second law of thermodynamics. We further find that an increase in sequence randomness leads to increasing randomness of GC content and longer sequence length. Taken together, our study presents an important finding, for the first time, that sequence randomness increases over time, which may provide profound insights for unveiling the underlying mechanisms of molecular sequence evolution. PMID:27224236

  12. Cluster randomization: a trap for the unwary.

    PubMed Central

    Underwood, M; Barnett, A; Hajioff, S

    1998-01-01

    Controlled trials that randomize by practice can provide robust evidence to inform patient care. However, compared with randomizing by each individual patient, this approach may have substantial implications for sample size calculations and the interpretation of results. An increased awareness of these effects will improve the quality of research based on randomization by practice. PMID:9624757

  13. Random Tensors and Planted Cliques

    NASA Astrophysics Data System (ADS)

    Brubaker, S. Charles; Vempala, Santosh S.

    The r-parity tensor of a graph is a generalization of the adjacency matrix, where the tensor’s entries denote the parity of the number of edges in subgraphs induced by r distinct vertices. For r = 2, it is the adjacency matrix with 1’s for edges and - 1’s for nonedges. It is well-known that the 2-norm of the adjacency matrix of a random graph is O(sqrt{n}). Here we show that the 2-norm of the r-parity tensor is at most f(r)sqrt{n}log^{O(r)}n, answering a question of Frieze and Kannan [1] who proved this for r = 3. As a consequence, we get a tight connection between the planted clique problem and the problem of finding a vector that approximates the 2-norm of the r-parity tensor of a random graph. Our proof method is based on an inductive application of concentration of measure.

  14. Random sources for cusped beams.

    PubMed

    Li, Jia; Wang, Fei; Korotkova, Olga

    2016-08-01

    We introduce two novel classes of partially coherent sources whose degrees of coherence are described by the rectangular Lorentz-correlated Schell-model (LSM) and rectangular fractional multi-Gaussian-correlated Schell-model (FMGSM) functions. Based on the generalized Collins formula, analytical expressions are derived for the spectral density distributions of these beams propagating through a stigmatic ABCD optical system. It is shown that beams belonging to both classes form the spectral density apex that is much higher and sharper than that generated by the Gaussian Schell-model (GSM) beam with a comparable coherence state. We experimentally generate these beams by using a nematic, transmissive spatial light modulator (SLM) that serves as a random phase screen controlled by a computer. The experimental data is consistent with theoretical predictions. Moreover, it is illustrated that the FMGSM beam generated in our experiments has a better focusing capacity than the GSM beam with the same coherence state. The applications that can potentially benefit from the use of novel beams range from material surface processing, to communications and sensing through random media. PMID:27505746

  15. The wasteland of random supergravities

    NASA Astrophysics Data System (ADS)

    Marsh, David; McAllister, Liam; Wrase, Timm

    2012-03-01

    We show that in a general {N} = {1} supergravity with N ≫ 1 scalar fields, an exponentially small fraction of the de Sitter critical points are metastable vacua. Taking the superpotential and Kähler potential to be random functions, we construct a random matrix model for the Hessian matrix, which is well-approximated by the sum of a Wigner matrix and two Wishart matrices. We compute the eigenvalue spectrum analytically from the free convolution of the constituent spectra and find that in typical configurations, a significant fraction of the eigenvalues are negative. Building on the Tracy-Widom law governing fluctuations of extreme eigenvalues, we determine the probability P of a large fluctuation in which all the eigenvalues become positive. Strong eigenvalue repulsion makes this extremely unlikely: we find P ∝ exp(- c N p ), with c, p being constants. For generic critical points we find p ≈ 1 .5, while for approximately-supersymmetric critical points, p ≈ 1 .3. Our results have significant implications for the counting of de Sitter vacua in string theory, but the number of vacua remains vast.

  16. Parabolic Anderson Model in a Dynamic Random Environment: Random Conductances

    NASA Astrophysics Data System (ADS)

    Erhard, D.; den Hollander, F.; Maillard, G.

    2016-06-01

    The parabolic Anderson model is defined as the partial differential equation ∂ u( x, t)/ ∂ t = κ Δ u( x, t) + ξ( x, t) u( x, t), x ∈ ℤ d , t ≥ 0, where κ ∈ [0, ∞) is the diffusion constant, Δ is the discrete Laplacian, and ξ is a dynamic random environment that drives the equation. The initial condition u( x, 0) = u 0( x), x ∈ ℤ d , is typically taken to be non-negative and bounded. The solution of the parabolic Anderson equation describes the evolution of a field of particles performing independent simple random walks with binary branching: particles jump at rate 2 d κ, split into two at rate ξ ∨ 0, and die at rate (- ξ) ∨ 0. In earlier work we looked at the Lyapunov exponents λ p(κ ) = limlimits _{tto ∞} 1/t log {E} ([u(0,t)]p)^{1/p}, quad p in {N} , qquad λ 0(κ ) = limlimits _{tto ∞} 1/2 log u(0,t). For the former we derived quantitative results on the κ-dependence for four choices of ξ : space-time white noise, independent simple random walks, the exclusion process and the voter model. For the latter we obtained qualitative results under certain space-time mixing conditions on ξ. In the present paper we investigate what happens when κΔ is replaced by Δ𝓚, where 𝓚 = {𝓚( x, y) : x, y ∈ ℤ d , x ˜ y} is a collection of random conductances between neighbouring sites replacing the constant conductances κ in the homogeneous model. We show that the associated annealed Lyapunov exponents λ p (𝓚), p ∈ ℕ, are given by the formula λ p({K} ) = {sup} {λ p(κ ) : κ in {Supp} ({K} )}, where, for a fixed realisation of 𝓚, Supp(𝓚) is the set of values taken by the 𝓚-field. We also show that for the associated quenched Lyapunov exponent λ 0(𝓚) this formula only provides a lower bound, and we conjecture that an upper bound holds when Supp(𝓚) is replaced by its convex hull. Our proof is valid for three classes of reversible ξ, and for all 𝓚

  17. Truly random number generation: an example

    NASA Astrophysics Data System (ADS)

    Frauchiger, Daniela; Renner, Renato

    2013-10-01

    Randomness is crucial for a variety of applications, ranging from gambling to computer simulations, and from cryptography to statistics. However, many of the currently used methods for generating randomness do not meet the criteria that are necessary for these applications to work properly and safely. A common problem is that a sequence of numbers may look random but nevertheless not be truly random. In fact, the sequence may pass all standard statistical tests and yet be perfectly predictable. This renders it useless for many applications. For example, in cryptography, the predictability of a "andomly" chosen password is obviously undesirable. Here, we review a recently developed approach to generating true | and hence unpredictable | randomness.

  18. On fatigue crack growth under random loading

    NASA Astrophysics Data System (ADS)

    Zhu, W. Q.; Lin, Y. K.; Lei, Y.

    1992-09-01

    A probabilistic analysis of the fatigue crack growth, fatigue life and reliability of a structural or mechanical component is presented on the basis of fracture mechanics and theory of random processes. The material resistance to fatigue crack growth and the time-history of the stress are assumed to be random. Analytical expressions are obtained for the special case in which the random stress is a stationary narrow-band Gaussian random process, and a randomized Paris-Erdogan law is applicable. As an example, the analytical method is applied to a plate with a central crack, and the results are compared with those obtained from digital Monte Carlo simulations.

  19. Functional Magnetic Resonance Imaging Neurofeedback-guided Motor Imagery Training and Motor Training for Parkinson’s Disease: Randomized Trial

    PubMed Central

    Subramanian, Leena; Morris, Monica Busse; Brosnan, Meadhbh; Turner, Duncan L.; Morris, Huw R.; Linden, David E. J.

    2016-01-01

    Objective: Real-time functional magnetic resonance imaging (rt-fMRI) neurofeedback (NF) uses feedback of the patient’s own brain activity to self-regulate brain networks which in turn could lead to a change in behavior and clinical symptoms. The objective was to determine the effect of NF and motor training (MOT) alone on motor and non-motor functions in Parkinson’s Disease (PD) in a 10-week small Phase I randomized controlled trial. Methods: Thirty patients with Parkinson’s disease (PD; Hoehn and Yahr I-III) and no significant comorbidity took part in the trial with random allocation to two groups. Group 1 (NF: 15 patients) received rt-fMRI-NF with MOT. Group 2 (MOT: 15 patients) received MOT alone. The primary outcome measure was the Movement Disorder Society—Unified PD Rating Scale-Motor scale (MDS-UPDRS-MS), administered pre- and post-intervention “off-medication”. The secondary outcome measures were the “on-medication” MDS-UPDRS, the PD Questionnaire-39, and quantitative motor assessments after 4 and 10 weeks. Results: Patients in the NF group were able to upregulate activity in the supplementary motor area (SMA) by using motor imagery. They improved by an average of 4.5 points on the MDS-UPDRS-MS in the “off-medication” state (95% confidence interval: −2.5 to −6.6), whereas the MOT group improved only by 1.9 points (95% confidence interval +3.2 to −6.8). The improvement in the intervention group meets the minimal clinically important difference which is also on par with other non-invasive therapies such as repetitive Transcranial Magnetic Stimulation (rTMS). However, the improvement did not differ significantly between the groups. No adverse events were reported in either group. Interpretation: This Phase I study suggests that NF combined with MOT is safe and improves motor symptoms immediately after treatment, but larger trials are needed to explore its superiority over active control conditions. PMID:27375451

  20. Specific strength training compared with interdisciplinary counseling for girls with tension-type headache: a randomized controlled trial

    PubMed Central

    Tornøe, Birte; Andersen, Lars L; Skotte, Jørgen H; Jensen, Rigmor; Jensen, Claus; Madsen, Bjarne K; Gard, Gunvor; Skov, Liselotte; Hallström, Inger

    2016-01-01

    Background Childhood tension-type headache (TTH) is a prevalent and debilitating condition for the child and family. Low-cost nonpharmacological treatments are usually the first choice of professionals and parents. This study examined the outcomes of specific strength training for girls with TTH. Methods Forty-nine girls aged 9–18 years with TTH were randomized to patient education programs with 10 weeks of strength training and compared with those who were counseled by a nurse and physical therapist. Primary outcomes were headache frequency, intensity, and duration; secondary outcomes were neck–shoulder muscle strength, aerobic power, and pericranial tenderness, measured at baseline, after 10 weeks intervention, and at 12 weeks follow-up. Health-related quality of life (HRQOL) questionnaires were assessed at baseline and after 24 months. Results For both groups, headache frequency decreased significantly, P=0.001, as did duration, P=0.022, with no significant between-group differences. The odds of having headache on a random day decreased over the 22 weeks by 0.65 (0.50–0.84) (odds ratio [95% confidence interval]). For both groups, neck extension strength decreased significantly with a decrease in cervicothoracic extension/flexion ratio to 1.7, indicating a positive change in muscle balance. In the training group, shoulder strength increased $10% in 5/20 girls and predicted VO2max increased $15% for 4/20 girls. In the training group, 50% of girls with a headache reduction of $30% had an increase in VO2max >5%. For the counseling group, this was the case for 29%. A 24-month follow-up on HRQOL for the pooled sample revealed statistically significant improvements. Fifty-five percent of the girls reported little to none disability. Conclusion The results indicate that both physical health and HRQOL can be influenced significantly by physical exercise and nurse counseling. More research is needed to examine the relationship between physical exercise, VO2max, and

  1. Modeling Randomness in Judging Rating Scales with a Random-Effects Rating Scale Model

    ERIC Educational Resources Information Center

    Wang, Wen-Chung; Wilson, Mark; Shih, Ching-Lin

    2006-01-01

    This study presents the random-effects rating scale model (RE-RSM) which takes into account randomness in the thresholds over persons by treating them as random-effects and adding a random variable for each threshold in the rating scale model (RSM) (Andrich, 1978). The RE-RSM turns out to be a special case of the multidimensional random…

  2. Causal Mediation Analyses for Randomized Trials.

    PubMed

    Lynch, Kevin G; Cary, Mark; Gallop, Robert; Ten Have, Thomas R

    2008-01-01

    In the context of randomized intervention trials, we describe causal methods for analyzing how post-randomization factors constitute the process through which randomized baseline interventions act on outcomes. Traditionally, such mediation analyses have been undertaken with great caution, because they assume that the mediating factor is also randomly assigned to individuals in addition to the randomized baseline intervention (i.e., sequential ignorability). Because the mediating factors are typically not randomized, such analyses are unprotected from unmeasured confounders that may lead to biased inference. We review several causal approaches that attempt to reduce such bias without assuming that the mediating factor is randomized. However, these causal approaches require certain interaction assumptions that may be assessed if there is enough treatment heterogeneity with respect to the mediator. We describe available estimation procedures in the context of several examples from the literature and provide resources for software code. PMID:19484136

  3. Certifying Unpredictable Randomness from Quantum Nonlocality

    NASA Astrophysics Data System (ADS)

    Bierhorst, Peter

    2015-03-01

    A device-independent quantum randomness protocol takes an initial random seed as input and then expands it in to a longer random string. It has been proven that if the initial random seed is trusted to be unpredictable, then the longer output string can also be certified to be unpredictable by an experimental violation of Bell's inequality. It has furthermore been argued that the initial random seed may not need to be truly unpredictable, but only uncorrelated to specific parts of the Bell experiment. In this work, we demonstrate rigorously that this is indeed true, under assumptions related to ``no superdeterminism/no conspiracy'' concepts along with the no-signaling assumption. So if we assume that superluminal signaling is impossible, then a loophole-free test of Bell's inequality would be able to generate provably unpredictable randomness from an input source of (potentially predictable) classical randomness.

  4. Security of practical private randomness generation

    NASA Astrophysics Data System (ADS)

    Pironio, Stefano; Massar, Serge

    2013-01-01

    Measurements on entangled quantum systems necessarily yield outcomes that are intrinsically unpredictable if they violate a Bell inequality. This property can be used to generate certified randomness in a device-independent way, i.e., without making detailed assumptions about the internal working of the quantum devices used to generate the random numbers. Furthermore these numbers are also private; i.e., they appear random not only to the user but also to any adversary that might possess a perfect description of the devices. Since this process requires a small initial random seed to sample the behavior of the quantum devices and to extract uniform randomness from the raw outputs of the devices, one usually speaks of device-independent randomness expansion. The purpose of this paper is twofold. First, we point out that in most real, practical situations, where the concept of device independence is used as a protection against unintentional flaws or failures of the quantum apparatuses, it is sufficient to show that the generated string is random with respect to an adversary that holds only classical side information; i.e., proving randomness against quantum side information is not necessary. Furthermore, the initial random seed does not need to be private with respect to the adversary, provided that it is generated in a way that is independent from the measured systems. The devices, however, will generate cryptographically secure randomness that cannot be predicted by the adversary, and thus one can, given access to free public randomness, talk about private randomness generation. The theoretical tools to quantify the generated randomness according to these criteria were already introduced in S. Pironio [Nature (London)NATUAS0028-083610.1038/nature09008 464, 1021 (2010)], but the final results were improperly formulated. The second aim of this paper is to correct this inaccurate formulation and therefore lay out a precise theoretical framework for practical device

  5. Postprocessing for quantum random-number generators: Entropy evaluation and randomness extraction

    NASA Astrophysics Data System (ADS)

    Ma, Xiongfeng; Xu, Feihu; Xu, He; Tan, Xiaoqing; Qi, Bing; Lo, Hoi-Kwong

    2013-06-01

    Quantum random-number generators (QRNGs) can offer a means to generate information-theoretically provable random numbers, in principle. In practice, unfortunately, the quantum randomness is inevitably mixed with classical randomness due to classical noises. To distill this quantum randomness, one needs to quantify the randomness of the source and apply a randomness extractor. Here, we propose a generic framework for evaluating quantum randomness of real-life QRNGs by min-entropy, and apply it to two different existing quantum random-number systems in the literature. Moreover, we provide a guideline of QRNG data postprocessing for which we implement two information-theoretically provable randomness extractors: Toeplitz-hashing extractor and Trevisan's extractor.

  6. Clique percolation in random networks.

    PubMed

    Derényi, Imre; Palla, Gergely; Vicsek, Tamás

    2005-04-29

    The notion of k-clique percolation in random graphs is introduced, where k is the size of the complete subgraphs whose large scale organizations are analytically and numerically investigated. For the Erdos-Rényi graph of N vertices we obtain that the percolation transition of k-cliques takes place when the probability of two vertices being connected by an edge reaches the threshold p(c) (k) = [(k - 1)N](-1/(k - 1)). At the transition point the scaling of the giant component with N is highly nontrivial and depends on k. We discuss why clique percolation is a novel and efficient approach to the identification of overlapping communities in large real networks. PMID:15904198

  7. Ergodic theory, randomness, and "chaos".

    PubMed

    Ornstein, D S

    1989-01-13

    Ergodic theory is the theory of the long-term statistical behavior of dynamical systems. The baker's transformation is an object of ergodic theory that provides a paradigm for the possibility of deterministic chaos. It can now be shown that this connection is more than an analogy and that at some level of abstraction a large number of systems governed by Newton's laws are the same as the baker's transformation. Going to this level of abstraction helps to organize the possible kinds of random behavior. The theory also gives new concrete results. For example, one can show that the same process could be produced by a mechanism governed by Newton's laws or by a mechanism governed by coin tossing. It also gives a statistical analog of structural stability. PMID:17747421

  8. Flow Through Randomly Curved Manifolds

    PubMed Central

    Mendoza, M.; Succi, S.; Herrmann, H. J.

    2013-01-01

    We present a computational study of the transport properties of campylotic (intrinsically curved) media. It is found that the relation between the flow through a campylotic media, consisting of randomly located curvature perturbations, and the average Ricci scalar of the system, exhibits two distinct functional expressions, depending on whether the typical spatial extent of the curvature perturbation lies above or below the critical value maximizing the overall scalar of curvature. Furthermore, the flow through such systems as a function of the number of curvature perturbations is found to present a sublinear behavior for large concentrations, due to the interference between curvature perturbations leading to an overall less curved space. We have also characterized the flux through such media as a function of the local Reynolds number and the scale of interaction between impurities. For the purpose of this study, we have also developed and validated a new lattice Boltzmann model. PMID:24173367

  9. Clique Percolation in Random Networks

    NASA Astrophysics Data System (ADS)

    Derényi, Imre; Palla, Gergely; Vicsek, Tamás

    2005-04-01

    The notion of k-clique percolation in random graphs is introduced, where k is the size of the complete subgraphs whose large scale organizations are analytically and numerically investigated. For the Erdős-Rényi graph of N vertices we obtain that the percolation transition of k-cliques takes place when the probability of two vertices being connected by an edge reaches the threshold pc(k)=[(k-1)N]-1/(k-1). At the transition point the scaling of the giant component with N is highly nontrivial and depends on k. We discuss why clique percolation is a novel and efficient approach to the identification of overlapping communities in large real networks.

  10. Structure of random bidisperse foam.

    SciTech Connect

    Reinelt, Douglas A.; van Swol, Frank B.; Kraynik, Andrew Michael

    2005-02-01

    The Surface Evolver was used to compute the equilibrium microstructure of random soap foams with bidisperse cell-size distributions and to evaluate topological and geometric properties of the foams and individual cells. The simulations agree with the experimental data of Matzke and Nestler for the probability {rho}(F) of finding cells with F faces and its dependence on the fraction of large cells. The simulations also agree with the theory for isotropic Plateau polyhedra (IPP), which describes the F-dependence of cell geometric properties, such as surface area, edge length, and mean curvature (diffusive growth rate); this is consistent with results for polydisperse foams. Cell surface areas are about 10% greater than spheres of equal volume, which leads to a simple but accurate relation for the surface free energy density of foams. The Aboav-Weaire law is not valid for bidisperse foams.

  11. Random vibration of compliant wall

    NASA Technical Reports Server (NTRS)

    Yang, J.-N.; Heller, R. A.

    1976-01-01

    The paper is concerned with the realistic case of two-dimensional random motion of a membrane with bending stiffness supported on a viscoelastic spring substrate and on an elastic base plate under both subsonic and supersonic boundary layer turbulence. The cross-power spectral density of surface displacements is solved in terms of design variables of the compliant wall - such as the dimensions and material properties of the membrane (Mylar), substrate (PVC foam), and panel (aluminum) - so that a sensitivity analysis can be made to examine the influence of each design variable on the surface response statistics. Three numerical examples typical of compliant wall design are worked out and their response statistics in relation to wave drag and roughness drag are assessed. The results can serve as a guideline for experimental investigation of the drag reduction concept through the use of a compliant wall.

  12. Extremal properties of random trees

    NASA Astrophysics Data System (ADS)

    Ben-Naim, E.; Krapivsky, P. L.; Majumdar, Satya N.

    2001-09-01

    We investigate extremal statistical properties such as the maximal and the minimal heights of randomly generated binary trees. By analyzing the master evolution equations we show that the cumulative distribution of extremal heights approaches a traveling wave form. The wave front in the minimal case is governed by the small-extremal-height tail of the distribution, and conversely, the front in the maximal case is governed by the large-extremal-height tail of the distribution. We determine several statistical characteristics of the extremal height distribution analytically. In particular, the expected minimal and maximal heights grow logarithmically with the tree size, N, hmin~vmin ln N, and hmax~vmax ln N, with vmin=0.373365... and vmax=4.31107..., respectively. Corrections to this asymptotic behavior are of order O(ln ln N).

  13. Effects of consuming fructose- or glucose-sweetened beverages for 10 weeks on lipids, insulin sensitivity and adiposity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Animal studies have documented that, compared with glucose, dietary fructose promotes dyslipidemia and insulin resistance. Experimental evidence that fructose consumption in humans promotes dyslipidemia and insulin resistance compared with glucose consumption has been equivocal. We tested the hypoth...

  14. Mechanical, hormonal, and hypertrophic adaptations to 10 weeks of eccentric and stretch-shortening cycle exercise training in old males.

    PubMed

    Váczi, Márk; Nagy, Szilvia A; Kőszegi, Tamás; Ambrus, Míra; Bogner, Péter; Perlaki, Gábor; Orsi, Gergely; Tóth, Katalin; Hortobágyi, Tibor

    2014-10-01

    The growth promoting effects of eccentric (ECC) contractions are well documented but it is unknown if the rate of stretch per se plays a role in such muscular responses in healthy aging human skeletal muscle. We tested the hypothesis that exercise training of the quadriceps muscle with low rate ECC and high rate ECC contractions in the form of stretch-shortening cycles (SSCs) but at equal total mechanical work would produce rate-specific adaptations in healthy old males age 60-70. Both training programs produced similar improvements in maximal voluntary isometric (6%) and ECC torque (23%) and stretch-shortening cycle function (reduced contraction duration [24%] and enhanced elastic energy storage [12%]) (p<0.05). The rate of torque development increased 30% only after SSC exercise (p<0.05). Resting testosterone and cortisol levels were unchanged but after each program the acute exercise-induced cortisol levels were 12-15% lower (p<0.05). Both programs increased quadriceps size 2.5% (p<0.05). It is concluded that both ECC and SSC exercise training produces favorable adaptations in healthy old males' quadriceps muscle. Although the rate of muscle tension during the SSC vs. ECC contractions was about 4-fold greater, the total mechanical work seems to regulate the hypetrophic, hormonal, and most of the mechanical adaptations. However, SSC exercise was uniquely effective in improving a key deficiency of aging muscle, i.e., its ability to produce force rapidly. PMID:25064038

  15. Lower bounds for randomized Exclusive Write PRAMs

    SciTech Connect

    MacKenzie, P.D.

    1995-05-02

    In this paper we study the question: How useful is randomization in speeding up Exclusive Write PRAM computations? Our results give further evidence that randomization is of limited use in these types of computations. First we examine a compaction problem on both the CREW and EREW PRAM models, and we present randomized lower bounds which match the best deterministic lower bounds known. (For the CREW PRAM model, the lower bound is asymptotically optimal.) These are the first non-trivial randomized lower bounds known for the compaction problem on these models. We show that our lower bounds also apply to the problem of approximate compaction. Next we examine the problem of computing boolean functions on the CREW PRAM model, and we present a randomized lower bound, which improves on the previous best randomized lower bound for many boolean functions, including the OR function. (The previous lower bounds for these functions were asymptotically optimal, but we improve the constant multiplicative factor.) We also give an alternate proof for the randomized lower bound on PARITY, which was already optimal to within a constant additive factor. Lastly, we give a randomized lower bound for integer merging on an EREW PRAM which matches the best deterministic lower bound known. In all our proofs, we use the Random Adversary method, which has previously only been used for proving lower bounds on models with Concurrent Write capabilities. Thus this paper also serves to illustrate the power and generality of this method for proving parallel randomized lower bounds.

  16. Error Threshold of Fully Random Eigen Model

    NASA Astrophysics Data System (ADS)

    Li, Duo-Fang; Cao, Tian-Guang; Geng, Jin-Peng; Qiao, Li-Hua; Gu, Jian-Zhong; Zhan, Yong

    2015-01-01

    Species evolution is essentially a random process of interaction between biological populations and their environments. As a result, some physical parameters in evolution models are subject to statistical fluctuations. In this work, two important parameters in the Eigen model, the fitness and mutation rate, are treated as Gaussian distributed random variables simultaneously to examine the property of the error threshold. Numerical simulation results show that the error threshold in the fully random model appears as a crossover region instead of a phase transition point, and as the fluctuation strength increases the crossover region becomes smoother and smoother. Furthermore, it is shown that the randomization of the mutation rate plays a dominant role in changing the error threshold in the fully random model, which is consistent with the existing experimental data. The implication of the threshold change due to the randomization for antiviral strategies is discussed.

  17. The MCNP5 Random number generator

    SciTech Connect

    Brown, F. B.; Nagaya, Y.

    2002-01-01

    MCNP and other Monte Carlo particle transport codes use random number generators to produce random variates from a uniform distribution on the interval. These random variates are then used in subsequent sampling from probability distributions to simulate the physical behavior of particles during the transport process. This paper describes the new random number generator developed for MCNP Version 5. The new generator will optionally preserve the exact random sequence of previous versions and is entirely conformant to the Fortran-90 standard, hence completely portable. In addition, skip-ahead algorithms have been implemented to efficiently initialize the generator for new histories, a capability that greatly simplifies parallel algorithms. Further, the precision of the generator has been increased, extending the period by a factor of 10{sup 5}. Finally, the new generator has been subjected to 3 different sets of rigorous and extensive statistical tests to verify that it produces a sufficiently random sequence.

  18. Duration of luteal support (DOLS) with progesterone pessaries to improve the success rates in assisted conception: study protocol for a randomized controlled trial

    PubMed Central

    2012-01-01

    Background Luteal support with progesterone is necessary for successful implantation of the embryo following egg collection and embryo transfer in an in-vitro fertilization (IVF) cycle. Progesterone has been used for as little as 2 weeks and for as long as 12 weeks of gestation. The optimal length of treatment is unresolved at present and it remains unclear how long to treat women receiving luteal supplementation. Design The trial is a prospective, randomized, double-blind, placebo-controlled trial to investigate the effect of the duration of luteal support with progesterone in IVF cycles. Following 2 weeks standard treatment and a positive biochemical pregnancy test, this randomized control trial will allocate women to a supplementary 8 weeks treatment with vaginal progesterone or 8 weeks placebo. Further studies would be required to investigate whether additional supplementation with progesterone is beneficial in early pregnancy. Discussion Currently at the Hewitt Centre, approximately 32.5% of women have a positive biochemical pregnancy test 2 weeks after embryo transfer. It is this population that is eligible for trial entry and randomization. Once the patient has confirmed a positive urinary pregnancy test they will be invited to join the trial. Once the consent form has been completed by the patient a trial prescription sheet will be sent to pharmacy with a stated collection time. The patient can then be randomized and the drugs dispensed according to pharmacy protocol. A blood sample will then be drawn for measurement of baseline hormone levels (progesterone, estradiol, free beta-human chorionic gonadotrophin, pregnancy-associated plasma protein-A, Activin A, Inhibin A and Inhibin B). The primary outcome measure is the proportion of all randomized women that continue successfully to a viable pregnancy (at least one fetus with fetal heart rate >100 beats/minute) on transabdominal/transvaginal ultrasound at 10 weeks post embryo transfer/12 weeks gestation

  19. Some physical applications of random hierarchical matrices

    SciTech Connect

    Avetisov, V. A.; Bikulov, A. Kh.; Vasilyev, O. A.; Nechaev, S. K.; Chertovich, A. V.

    2009-09-15

    The investigation of spectral properties of random block-hierarchical matrices as applied to dynamic and structural characteristics of complex hierarchical systems with disorder is proposed for the first time. Peculiarities of dynamics on random ultrametric energy landscapes are discussed and the statistical properties of scale-free and polyscale (depending on the topological characteristics under investigation) random hierarchical networks (graphs) obtained by multiple mapping are considered.

  20. Private randomness expansion with untrusted devices

    NASA Astrophysics Data System (ADS)

    Colbeck, Roger; Kent, Adrian

    2011-03-01

    Randomness is an important resource for many applications, from gambling to secure communication. However, guaranteeing that the output from a candidate random source could not have been predicted by an outside party is a challenging task, and many supposedly random sources used today provide no such guarantee. Quantum solutions to this problem exist, for example a device which internally sends a photon through a beamsplitter and observes on which side it emerges, but, presently, such solutions require the user to trust the internal workings of the device. Here, we seek to go beyond this limitation by asking whether randomness can be generated using untrusted devices—even ones created by an adversarial agent—while providing a guarantee that no outside party (including the agent) can predict it. Since this is easily seen to be impossible unless the user has an initially private random string, the task we investigate here is private randomness expansion. We introduce a protocol for private randomness expansion with untrusted devices which is designed to take as input an initially private random string and produce as output a longer private random string. We point out that private randomness expansion protocols are generally vulnerable to attacks that can render the initial string partially insecure, even though that string is used only inside a secure laboratory; our protocol is designed to remove this previously unconsidered vulnerability by privacy amplification. We also discuss extensions of our protocol designed to generate an arbitrarily long random string from a finite initially private random string. The security of these protocols against the most general attacks is left as an open question.

  1. Disturbing the random-energy landscape

    NASA Astrophysics Data System (ADS)

    Halpin-Healy, Timothy; Herbert, Devorah

    1993-09-01

    We examine the effects of correlated perturbations upon globally optimal paths through a random-energy landscape. Motivated by Zhang's early numerical investigations [Phys. Rev. Lett. 59, 2125 (1987)] into ground-state instabilities of disordered systems, as well as the work of Shapir [Phys. Rev. Lett. 66, 1473 (1991)] on random perturbations of roughened manifolds, we have studied the specific case of random bond interfaces unsettled by small random fields, confirming recent predictions for the instability exponents. Implications for disordered magnets and growing surfaces are discussed.

  2. The Theory of Random Laser Systems

    SciTech Connect

    Xunya Jiang

    2002-06-27

    Studies of random laser systems are a new direction with promising potential applications and theoretical interest. The research is based on the theories of localization and laser physics. So far, the research shows that there are random lasing modes inside the systems which is quite different from the common laser systems. From the properties of the random lasing modes, they can understand the phenomena observed in the experiments, such as multi-peak and anisotropic spectrum, lasing mode number saturation, mode competition and dynamic processes, etc. To summarize, this dissertation has contributed the following in the study of random laser systems: (1) by comparing the Lamb theory with the Letokhov theory, the general formulas of the threshold length or gain of random laser systems were obtained; (2) they pointed out the vital weakness of previous time-independent methods in random laser research; (3) a new model which includes the FDTD method and the semi-classical laser theory. The solutions of this model provided an explanation of the experimental results of multi-peak and anisotropic emission spectra, predicted the saturation of lasing modes number and the length of localized lasing modes; (4) theoretical (Lamb theory) and numerical (FDTD and transfer-matrix calculation) studies of the origin of localized lasing modes in the random laser systems; and (5) proposal of using random lasing modes as a new path to study wave localization in random systems and prediction of the lasing threshold discontinuity at mobility edge.

  3. True random numbers from amplified quantum vacuum.

    PubMed

    Jofre, M; Curty, M; Steinlechner, F; Anzolin, G; Torres, J P; Mitchell, M W; Pruneri, V

    2011-10-10

    Random numbers are essential for applications ranging from secure communications to numerical simulation and quantitative finance. Algorithms can rapidly produce pseudo-random outcomes, series of numbers that mimic most properties of true random numbers while quantum random number generators (QRNGs) exploit intrinsic quantum randomness to produce true random numbers. Single-photon QRNGs are conceptually simple but produce few random bits per detection. In contrast, vacuum fluctuations are a vast resource for QRNGs: they are broad-band and thus can encode many random bits per second. Direct recording of vacuum fluctuations is possible, but requires shot-noise-limited detectors, at the cost of bandwidth. We demonstrate efficient conversion of vacuum fluctuations to true random bits using optical amplification of vacuum and interferometry. Using commercially-available optical components we demonstrate a QRNG at a bit rate of 1.11 Gbps. The proposed scheme has the potential to be extended to 10 Gbps and even up to 100 Gbps by taking advantage of high speed modulation sources and detectors for optical fiber telecommunication devices. PMID:21997077

  4. Random packing of spheres in Menger sponge

    NASA Astrophysics Data System (ADS)

    Cieśla, Michał; Barbasz, Jakub

    2013-06-01

    Random packing of spheres inside fractal collectors of dimension 2 < d < 3 is studied numerically using Random Sequential Adsorption (RSA) algorithm. The paper focuses mainly on the measurement of random packing saturation limit. Additionally, scaling properties of density autocorrelations in the obtained packing are analyzed. The RSA kinetics coefficients are also measured. Obtained results allow to test phenomenological relation between random packing saturation density and collector dimension. Additionally, performed simulations together with previously obtained results confirm that, in general, the known dimensional relations are obeyed by systems having non-integer dimension, at least for d < 3.

  5. Random packing of spheres in Menger sponge.

    PubMed

    Cieśla, Michał; Barbasz, Jakub

    2013-06-01

    Random packing of spheres inside fractal collectors of dimension 2 < d < 3 is studied numerically using Random Sequential Adsorption (RSA) algorithm. The paper focuses mainly on the measurement of random packing saturation limit. Additionally, scaling properties of density autocorrelations in the obtained packing are analyzed. The RSA kinetics coefficients are also measured. Obtained results allow to test phenomenological relation between random packing saturation density and collector dimension. Additionally, performed simulations together with previously obtained results confirm that, in general, the known dimensional relations are obeyed by systems having non-integer dimension, at least for d < 3. PMID:23758392

  6. A Mixed Flavonoid-Fish Oil Supplement Induces Immune-Enhancing and Anti-Inflammatory Transcriptomic Changes in Adult Obese and Overweight Women—A Randomized Controlled Trial

    PubMed Central

    Cialdella-Kam, Lynn; Nieman, David C.; Knab, Amy M.; Shanely, R. Andrew; Meaney, Mary Pat; Jin, Fuxia; Sha, Wei; Ghosh, Sujoy

    2016-01-01

    Flavonoids and fish oils have anti-inflammatory and immune-modulating influences. The purpose of this study was to determine if a mixed flavonoid-fish oil supplement (Q-Mix; 1000 mg quercetin, 400 mg isoquercetin, 120 mg epigallocatechin (EGCG) from green tea extract, 400 mg n3-PUFAs (omega-3 polyunsaturated fatty acid) (220 mg eicosapentaenoic acid (EPA) and 180 mg docosahexaenoic acid (DHA)) from fish oil, 1000 mg vitamin C, 40 mg niacinamide, and 800 µg folic acid) would reduce complications associated with obesity; that is, reduce inflammatory and oxidative stress markers and alter genomic profiles in overweight women. Overweight and obese women (n = 48; age = 40–70 years) were assigned to Q-Mix or placebo groups using randomized double-blinded placebo-controlled procedures. Overnight fasted blood samples were collected at 0 and 10 weeks and analyzed for cytokines, C-reactive protein (CRP), F2-isoprostanes, and whole-blood-derived mRNA, which was assessed using Affymetrix HuGene-1_1 ST arrays. Statistical analysis included two-way ANOVA models for blood analytes and gene expression and pathway and network enrichment methods for gene expression. Plasma levels increased with Q-Mix supplementation by 388% for quercetin, 95% for EPA, 18% for DHA, and 20% for docosapentaenoic acid (DPA). Q-Mix did not alter plasma levels for CRP (p = 0.268), F2-isoprostanes (p = 0.273), and cytokines (p > 0.05). Gene set enrichment analysis revealed upregulation of pathways in Q-Mix vs. placebo related to interferon-induced antiviral mechanism (false discovery rate, FDR < 0.001). Overrepresentation analysis further disclosed an inhibition of phagocytosis-related inflammatory pathways in Q-Mix vs. placebo. Thus, a 10-week Q-Mix supplementation elicited a significant rise in plasma quercetin, EPA, DHA, and DPA, as well as stimulated an antiviral and inflammation whole-blood transcriptomic response in overweight women. PMID:27187447

  7. The Impact of a Low Glycemic Index Diet on Inflammatory Markers and Serum Adiponectin Concentration in Adolescent Overweight and Obese Girls: A Randomized Clinical Trial.

    PubMed

    Rouhani, M H; Kelishadi, R; Hashemipour, M; Esmaillzadeh, A; Surkan, P J; Keshavarz, A; Azadbakht, L

    2016-04-01

    Although the effects of dietary glycemic index (GI) on insulin resistance are well documented in adults, the complex interaction among glucose intolerance, inflammatory markers, and adipokine concentration has not been well studied, especially among adolescents. We investigated the effect of a low glycemic index (LGI) diet on insulin concentration, fasting blood sugar (FBS), inflammatory markers, and serum adiponectin concentration among healthy obese/overweight adolescent females. In this parallel randomized clinical trial, 2 different diets, an LGI diet and a healthy nutritional recommendation diet (HNRD) with similar macronutrient composition were prescribed to 50 obese and overweight adolescent girls with the same pubertal status. Biochemical markers FBS, serum insulin concentration, high sensitivity C-reactive protein (hs-CRP), interleukin 6 (IL-6), and adiponectin were measured before and after a 10 week intervention. Using an intention-to-treat analysis, data from 50 subjects were analyzed. According to a dietary assessment, GI in the LGI group was 43.22±0.54. While the mean for FBS, serum insulin concentration, the homeostasis model assessment (HOMA), the quantitative insulin sensitivity check index (QUICKI), and adiponectin concentration did not differ significantly within each group, the average hs-CRP and IL-6 decreased significantly in the LGI diet group after the 10 week intervention (p=0.009 and p=0.001; respectively). Comparing percent changes, we found a marginally significant decrease in hs-CRP in the LGI group compared with the HNRD group after adjusting for confounders. Compliance with an LGI diet may have favorable effect on inflammation among overweight and obese adolescent girls. PMID:27065462

  8. A Mixed Flavonoid-Fish Oil Supplement Induces Immune-Enhancing and Anti-Inflammatory Transcriptomic Changes in Adult Obese and Overweight Women-A Randomized Controlled Trial.

    PubMed

    Cialdella-Kam, Lynn; Nieman, David C; Knab, Amy M; Shanely, R Andrew; Meaney, Mary Pat; Jin, Fuxia; Sha, Wei; Ghosh, Sujoy

    2016-01-01

    Flavonoids and fish oils have anti-inflammatory and immune-modulating influences. The purpose of this study was to determine if a mixed flavonoid-fish oil supplement (Q-Mix; 1000 mg quercetin, 400 mg isoquercetin, 120 mg epigallocatechin (EGCG) from green tea extract, 400 mg n3-PUFAs (omega-3 polyunsaturated fatty acid) (220 mg eicosapentaenoic acid (EPA) and 180 mg docosahexaenoic acid (DHA)) from fish oil, 1000 mg vitamin C, 40 mg niacinamide, and 800 µg folic acid) would reduce complications associated with obesity; that is, reduce inflammatory and oxidative stress markers and alter genomic profiles in overweight women. Overweight and obese women (n = 48; age = 40-70 years) were assigned to Q-Mix or placebo groups using randomized double-blinded placebo-controlled procedures. Overnight fasted blood samples were collected at 0 and 10 weeks and analyzed for cytokines, C-reactive protein (CRP), F₂-isoprostanes, and whole-blood-derived mRNA, which was assessed using Affymetrix HuGene-1_1 ST arrays. Statistical analysis included two-way ANOVA models for blood analytes and gene expression and pathway and network enrichment methods for gene expression. Plasma levels increased with Q-Mix supplementation by 388% for quercetin, 95% for EPA, 18% for DHA, and 20% for docosapentaenoic acid (DPA). Q-Mix did not alter plasma levels for CRP (p = 0.268), F2-isoprostanes (p = 0.273), and cytokines (p > 0.05). Gene set enrichment analysis revealed upregulation of pathways in Q-Mix vs. placebo related to interferon-induced antiviral mechanism (false discovery rate, FDR < 0.001). Overrepresentation analysis further disclosed an inhibition of phagocytosis-related inflammatory pathways in Q-Mix vs. placebo. Thus, a 10-week Q-Mix supplementation elicited a significant rise in plasma quercetin, EPA, DHA, and DPA, as well as stimulated an antiviral and inflammation whole-blood transcriptomic response in overweight women. PMID:27187447

  9. Migration in asymmetric, random environments

    NASA Astrophysics Data System (ADS)

    Deem, Michael; Wang, Dong

    Migration is a key mechanism for expansion of communities. As a population migrates, it experiences a changing environment. In heterogeneous environments, rapid adaption is key to the evolutionary success of the population. In the case of human migration, environmental heterogeneity is naturally asymmetric in the North-South and East-West directions. We here consider migration in random, asymmetric, modularly correlated environments. Knowledge about the environment determines the fitness of each individual. We find that the speed of migration is proportional to the inverse of environmental change, and in particular we find that North-South migration rates are lower than East-West migration rates. Fast communication within the population of pieces of knowledge between individuals, similar to horizontal gene transfer in genetic systems, can help to spread beneficial knowledge among individuals. We show that increased modularity of the relation between knowledge and fitness enhances the rate of evolution. We investigate the relation between optimal information exchange rate and modularity of the dependence of fitness on knowledge. These results for the dependence of migration rate on heterogeneity, asymmetry, and modularity are consistent with existing archaeological facts.

  10. Hierarchy in directed random networks

    NASA Astrophysics Data System (ADS)

    Mones, Enys

    2013-02-01

    In recent years, the theory and application of complex networks have been quickly developing in a markable way due to the increasing amount of data from real systems and the fruitful application of powerful methods used in statistical physics. Many important characteristics of social or biological systems can be described by the study of their underlying structure of interactions. Hierarchy is one of these features that can be formulated in the language of networks. In this paper we present some (qualitative) analytic results on the hierarchical properties of random network models with zero correlations and also investigate, mainly numerically, the effects of different types of correlations. The behavior of the hierarchy is different in the absence and the presence of giant components. We show that the hierarchical structure can be drastically different if there are one-point correlations in the network. We also show numerical results suggesting that the hierarchy does not change monotonically with the correlations and there is an optimal level of nonzero correlations maximizing the level of hierarchy.