The effect of long working hours on cerebrovascular and cardiovascular disease; A case-crossover study.

PubMed

Shin, Kyong-Sok; Chung, Yun Kyung; Kwon, Young-Jun; Son, Jun-Seok; Lee, Se-Hoon

2017-09-01

This study investigated the relationship between weekly working hours and the occurrence of cerebro-cardiovascular diseases using a case-crossover study design. We investigated average working hours during the 7 days before the onset of illness (hazard period) and average weekly working hours between 8 days and 3 months before the onset of cerebro-cardiovascular diseases (control period) for 1,042 cases from the workers' compensation database for 2009. Among all subjects, the odds ratio by conditional logistic regression for the risk of cerebro-cardiovascular diseases with a 10 hr increase in average weekly working hours was 1.45 (95% confidence interval [CI]: 1.22-1.72), a significant association. An increase in average weekly working hours may trigger the onset of cerebro-cardiovascular disease. Am. J. Ind. Med. 60:753-761, 2017. © 2017. Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Association of Ambient Air Pollution with Respiratory Hospitalization in a Government-Designated “Area of Concern”: The Case of Windsor, Ontario

PubMed Central

Luginaah, Isaac N.; Fung, Karen Y.; Gorey, Kevin M.; Webster, Greg; Wills, Chris

2005-01-01

This study is part of a larger research program to examine the relationship between ambient air quality and health in Windsor, Ontario, Canada. We assessed the association between air pollution and daily respiratory hospitalization for different age and sex groups from 1995 to 2000. The pollutants included were nitrogen dioxide, sulfur dioxide, carbon monoxide, ozone, particulate matter ≤10 μm in diameter (PM10), coefficient of haze (COH), and total reduced sulfur (TRS). We calculated relative risk (RR) estimates using both time-series and case-crossover methods after controlling for appropriate confounders (temperature, humidity, and change in barometric pressure). The results of both analyses were consistent. We found associations between NO2, SO2, CO, COH, or PM10 and daily hospital admission of respiratory diseases especially among females. For females 0–14 years of age, there was 1-day delayed effect of NO2 (RR = 1.19, case-crossover method), a current-day SO2 (RR = 1.11, time series), and current-day and 1- and 2-day delayed effects for CO by case crossover (RR = 1.15, 1.19, 1.22, respectively). Time-series analysis showed that 1-day delayed effect of PM10 on respiratory admissions of adult males (15–64 years of age), with an RR of 1.18. COH had significant effects on female respiratory hospitalization, especially for 2-day delayed effects on adult females, with RRs of 1.15 and 1.29 using time-series and case-crossover analysis, respectively. There were no significant associations between O3 and TRS with respiratory admissions. These findings provide policy makers with current risks estimates of respiratory hospitalization as a result of poor ambient air quality in a government designated “area of concern.” PMID:15743717

Refined ambient PM2.5 exposure surrogates and the risk of myocardial infarction

EPA Science Inventory

Using a case-crossover study design and conditional logistic regression, we compared the relative odds of transmural (full-wall) myocardial infarction (MI) calculated using exposure surrogates that account for human activity patterns and the indoor transport of ambient PM_2....

Persistent threats to validity in single-group interrupted time series analysis with a cross over design.

PubMed

Linden, Ariel

2017-04-01

The basic single-group interrupted time series analysis (ITSA) design has been shown to be susceptible to the most common threat to validity-history-the possibility that some other event caused the observed effect in the time series. A single-group ITSA with a crossover design (in which the intervention is introduced and withdrawn 1 or more times) should be more robust. In this paper, we describe and empirically assess the susceptibility of this design to bias from history. Time series data from 2 natural experiments (the effect of multiple repeals and reinstatements of Louisiana's motorcycle helmet law on motorcycle fatalities and the association between the implementation and withdrawal of Gorbachev's antialcohol campaign with Russia's mortality crisis) are used to illustrate that history remains a threat to ITSA validity, even in a crossover design. Both empirical examples reveal that the single-group ITSA with a crossover design may be biased because of history. In the case of motorcycle fatalities, helmet laws appeared effective in reducing mortality (while repealing the law increased mortality), but when a control group was added, it was shown that this trend was similar in both groups. In the case of Gorbachev's antialcohol campaign, only when contrasting the results against those of a control group was the withdrawal of the campaign found to be the more likely culprit in explaining the Russian mortality crisis than the collapse of the Soviet Union. Even with a robust crossover design, single-group ITSA models remain susceptible to bias from history. Therefore, a comparable control group design should be included, whenever possible. © 2016 John Wiley & Sons, Ltd.

Travel abroad increases sexual health risk-taking among Swedish youth: a population-based study using a case-crossover strategy

PubMed Central

Sundbeck, Mats; Agardh, Anette; Östergren, Per-Olof

2017-01-01

ABSTRACT Background: The fact that youth take sexual risks when they are abroad have been shown in previous studies. However, it is not known if they increased their sexual risk-taking when travelling abroad, compared to the stay in their homeland. Objective: To assess whether Swedish youth increased their individual sexual risk behaviour, defined as having a casual sex partner, when travelling abroad and to examine possible factors that may be associated with increased risk-taking abroad. Design: In 2013, a population-based sample of 2189 Swedes, 18-29 years, was assessed by a questionnaire (45% response rate). Sexuality, duration of travel, parents’ country of origin, mental health, heavy episodic drinking (HED), use of illicit drugs, and socio-demographic background were assessed. Increased risk of casual sex in relation to time spent abroad vs. time spent in Sweden was analysed by a variant of case-crossover design. Factors that could be associated with increased risk of casual sex in Sweden and abroad, separately, were analysed by logistic regression. PMID:28598729

A short-term effect of low-dose aspirin on major hemorrhagic risks in primary prevention: a case-crossover design.

PubMed

Wu, I-Chen; Lin, Ming-Yen; Yu, Fang-Jung; Hsieh, Hui-Min; Chiu, Kuei-Fen; Wu, Ming-Tsang

2014-01-01

Very few studies have examined the risk of short-term adverse hemorrhage of low-dose aspirin use in primary prevention. This case-crossover study examined the transient effect of low-dose aspirin use on major hemorrhagic risks. A representative database of 1,000,000 patients randomly sampled from the Taiwan's National Health Insurance Research Database in 2000 was analyzed. The study cohort consisted of a total of 501,946 individuals, aged 30-95 years old, at risk of a major bleeding event in 2000. A case-crossover study was used to retrieve data on 10,905 incident patients with major hemorrhagic complications (3,781 cerebral and 7,124 gastrointestinal) and prescribed low-dose aspirin (≤300 mg/day) from 2000-2008. A 56-day time window (∼2 months) was used as the case period for which the odds ratio (OR) was estimated using the ratio of patients exposed during the 56-day case period only (1-56 days before the index date) compared to its corresponding 56-day control period only (57-112 days before the index date). Four hundred eighty-nine (4.5%) of the 10,905 hemorrhagic patients had used low-dose aspirin during the 56-day case only period; 294 (2.7%) of the same patients had used low-dose aspirin during control only period. Low-dose aspirin use increase the risk of developing a major hemorrhage 1.33-fold (95% CI = 1.13-1.55, P<0.0001). Significance was found prominent in 4,453 non-hypertensive and non-diabetic subjects (Adjusted odds ratio = 1.88, 95% CI = 1.21-2.91). Transient low-dose aspirin use increases risk for major hemorrhagic events in Han Chinese.

Risk of Liver Injury Associated with Chinese Herbal Products Containing Radix bupleuri in 639,779 Patients with Hepatitis B Virus Infection

PubMed Central

Lee, Chang-Hsing; Wang, Jung-Der; Chen, Pau-Chung

2011-01-01

Background Chinese herbal products (CHPs) containing Radix bupleuri are often prescribed for chronic hepatitis. There have been no epidemiological studies in populations with hepatitis B virus (HBV) infection. Our study was conducted to determine the association between the use of CHPs containing Radix bupleuri and the risk of hospitalisation related to liver injury among HBV-infected patients in Taiwan. Methods From a total of 639,779 patients with diagnoses related to HBV infection, we included hospitalised adult cases with a primary diagnosis of liver injury in the database of Taiwan's national health insurance during the period 1997–2004. Case-control and case-crossover designs were used to assess the risk of hospitalisation with conditional logistic regression models constructed and adjusted for 270 conventionally hepatotoxic drugs. Cumulative doses of these CHPs and Radix bupleuri were assessed for any dose-response relationship. Findings In total, we collected 1,080 cases fulfilled the inclusion criteria. In the case-control design, the adjusted odds ratio was 1.90 (95% confidence interval [CI]: 1.30 to 2.77). The risks from prescribing the CHPs Xiao-Chai-Hu-Tang and Long-Dan-Xie-Gan-Tang were significantly high, and dose-response relationships were found. The risk of adding each 19 gm dose of Radix bupleuri was 2.19 (95% CI: 1.66 to 2.89). The results using the case-crossover design remained similar. Conclusions Prescribing Xiao-Chai-Hu-Tang, Long-Dan-Xie-Gan-Tang, or CHPs containing more than 19 gram of Radix bupleuri in HBV-infected patients might increase their risks of liver injury. Further studies are indicated to corroborate the above findings. PMID:21264326

Design, Analysis, and Reporting of Crossover Trials for Inclusion in a Meta-Analysis.

PubMed

Li, Tianjing; Yu, Tsung; Hawkins, Barbara S; Dickersin, Kay

2015-01-01

To evaluate the characteristics of the design, analysis, and reporting of crossover trials for inclusion in a meta-analysis of treatment for primary open-angle glaucoma and to provide empirical evidence to inform the development of tools to assess the validity of the results from crossover trials and reporting guidelines. We searched MEDLINE, EMBASE, and Cochrane's CENTRAL register for randomized crossover trials for a systematic review and network meta-analysis we are conducting. Two individuals independently screened the search results for eligibility and abstracted data from each included report. We identified 83 crossover trials eligible for inclusion. Issues affecting the risk of bias in crossover trials, such as carryover, period effects and missing data, were often ignored. Some trials failed to accommodate the within-individual differences in the analysis. For a large proportion of the trials, the authors tabulated the results as if they arose from a parallel design. Precision estimates properly accounting for the paired nature of the design were often unavailable from the study reports; consequently, to include trial findings in a meta-analysis would require further manipulation and assumptions. The high proportion of poorly reported analyses and results has the potential to affect whether crossover data should or can be included in a meta-analysis. There is pressing need for reporting guidelines for crossover trials.

Case-crossover study of Burkholderia cepacia complex bloodstream infection associated with contaminated intravenous bromopride.

PubMed

Martins, Ianick Souto; Pellegrino, Flávia Lúcia Piffano Costa; Freitas, Andrea d'Avila; Santos, Marisa da Silva; Ferraiuoli, Giovanna Ianini d'Alemeida; Vasques, Márcia Regina Guimarães; Amorim, Efigenia Lourdes Teixeira; Oliveira, Sandra; Nouér, Simone Aranha; Cardoso, Fernando Luiz Lopes; Mascarenhas, Luiz Affonso; Magalhães, Ana Cristina Gouveia; Cleinman, Isabella Barbosa; Figueiredo, Agnes Marie Sá; Moreira, Beatriz Meurer

2010-05-01

To investigate an outbreak of healthcare-associated Burkholderia cepacia complex (BCC) primary bloodstream infections (BCC-BSI). Case-crossover study in a public hospital, a university hospital and a private hospital in Rio de Janeiro, Brazil, from March 2006 to May 2006. Twenty-five patients with BCC-BSI. After determining the date BCC-BSI symptoms started for each patient, 3 time intervals of data collection were defined, each one with a duration of 3 days: the case period, starting just before BCC-BSI symptoms onset; the control period, starting 6 days before BCC-BSI symptoms onset; and the washout period, comprising the 3 days between the case period and the control period. Exposures evaluated were intravascular solutions and invasive devices and procedures. Potential risk factors were identified by using the McNemar chi(2) adjusted test. Cultures of samples of potentially contaminated solutions were performed. BCC strain typing was performed by pulsed-field gel electrophoresis using SpeI. The statistical analysis revealed that the use of bromopride and dipyrone was associated with BCC-BSI. A total of 21 clinical isolates from 17 (68%) of the 25 patients and an isolate obtained from the bromopride vial were available for strain typing. Six pulsotypes were detected. A predominant pulsotype (A) accounted for 11 isolates obtained from 11 patients (65%) in the 3 study hospitals. Our investigation, using a case-crossover design, of an outbreak of BCC-BSI infections concluded it was polyclonal but likely caused by infusion of contaminated bromopride. The epidemiological finding was validated by microbiological analysis. After recall of contaminated bromopride vials by the manufacturer, the outbreak was controlled.

Use of Self-Matching to Control for Stable Patient Characteristics While Addressing Time-Varying Confounding on Treatment Effect: A Case Study of Older Intensive Care Patients.

PubMed

Han, Ling; Pisani, M A; Araujo, K L B; Allore, Heather G

Exposure-crossover design offers a non-experimental option to control for stable baseline confounding through self-matching while examining causal effect of an exposure on an acute outcome. This study extends this approach to longitudinal data with repeated measures of exposure and outcome using data from a cohort of 340 older medical patients in an intensive care unit (ICU). The analytic sample included 92 patients who received ≥1 dose of haloperidol, an antipsychotic medication often used for patients with delirium. Exposure-crossover design was implemented by sampling the 3-day time segments prior ( Induction) and posterior ( Subsequent) to each treatment episode of receiving haloperidol. In the full cohort, there was a trend of increasing delirium severity scores (Mean±SD: 4.4±1.7) over the course of the ICU stay. After exposure-crossover sampling, the delirium severity score decreased from the Induction (4.9) to the Subsequent (4.1) intervals, with the treatment episode falling in-between (4.5). Based on a GEE Poisson model accounting for self-matching and within-subject correlation, the unadjusted mean delirium severity scores was -0.55 (95% CI: -1.10, -0.01) points lower for the Subsequent than the Induction intervals. The association diminished by 32% (-0.38, 95%CI: -0.99, 0.24) after adjusting only for ICU confounding, while being slightly increased by 7% (-0.60, 95%CI: -1.15, -0.04) when adjusting only for baseline characteristics. These results suggest that longitudinal exposure-crossover design is feasible and capable of partially removing stable baseline confounding through self-matching. Loss of power due to eliminating treatment-irrelevant person-time and uncertainty around allocating person-time to comparison intervals remain methodological challenges.

A case-crossover study of transient risk factors influence on occupational injuries: a study protocol based on a review of previous studies.

PubMed

Oesterlund, Anna H; Lander, Flemming; Lauritsen, Jens

2016-10-01

The occupational injury incident rate remains relatively high in the European Union. The case-crossover study gives a unique opportunity to study transient risk factors that normally would be very difficult to approach. Studies like this have been carried out in both America and Asia, but so far no relevant research has been conducted in Europe. Case-crossover studies of occupational injuries were collected from PubMed and Embase and read through. Previous experiences concerning method, exposure and outcome, time-related measurements and construction of the questionnaire were taken into account in the preparation of a pilot study. Consequently, experiences from the pilot study were used to design the study protocol. Approximately 2000 patients with an occupational injury will be recruited from the emergency departments in Herning and Odense, Denmark. A standardised questionnaire will be used to collect basic demographic data and information on eight transient risk factors. Based on previous studies and knowledge on occupational injuries the transient risk factors we chose to examine were: time pressure, performing a task with a different method/using unaccustomed technique, change in working surroundings, using a phone, disagreement, feeling ill, being distracted and using malfunctioning machinery/tools or work material. Exposure time 'just before the injury' will be compared with two control periods, 'previous day at the same time of the injury' (pair match) and the previous work week (usual frequency). This study protocol describes a unique opportunity to calculate the effect of transient risk factors on occupational injuries in a European setting. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

PM₁₀ exposure and non-accidental mortality in Asian populations: a meta-analysis of time-series and case-crossover studies.

PubMed

Park, Hye Yin; Bae, Sanghyuk; Hong, Yun-Chul

2013-01-01

We investigated the association between particulate matter less than 10 µm in aerodynamic diameter (PM₁₀) exposure and non-accidental mortality in Asian populations by meta-analysis, using both time-series and case-crossover analysis. Among the 819 published studies searched from PubMed and EMBASE using key words related to PM₁₀ exposure and non-accidental mortality in Asian countries, 8 time-series and 4 case-crossover studies were selected for meta-analysis after exclusion by selection criteria. We obtained the relative risk (RR) and 95% confidence intervals (CI) of non-accidental mortality per 10 µg/m³ increase of daily PM₁₀ from each study. We used Q statistics to test the heterogeneity of the results among the different studies and evaluated for publication bias using Begg funnel plot and Egger test. Testing for heterogeneity showed significance (p<0.001); thus, we applied a random-effects model. RR (95% CI) per 10 µg/m³ increase of daily PM₁₀ for both the time-series and case-crossover studies combined, time-series studies relative risk only, and case-crossover studies only, were 1.0047 (1.0033 to 1.0062), 1.0057 (1.0029 to 1.0086), and 1.0027 (1.0010 to 1.0043), respectively. The non-significant Egger test suggested that this analysis was not likely to have a publication bias. We found a significant positive association between PM₁₀ exposure and non-accidental mortality among Asian populations. Continued investigations are encouraged to contribute to the health impact assessment and public health management of air pollution in Asian countries.

Travel abroad increases sexual health risk-taking among Swedish youth: a population-based study using a case-crossover strategy.

PubMed

Sundbeck, Mats; Agardh, Anette; Östergren, Per-Olof

2017-01-01

The fact that youth take sexual risks when they are abroad have been shown in previous studies. However, it is not known if they increased their sexual risk-taking when travelling abroad, compared to the stay in their homeland. To assess whether Swedish youth increased their individual sexual risk behaviour, defined as having a casual sex partner, when travelling abroad and to examine possible factors that may be associated with increased risk-taking abroad. In 2013, a population-based sample of 2189 Swedes, 18-29 years, was assessed by a questionnaire (45% response rate). Sexuality, duration of travel, parents' country of origin, mental health, heavy episodic drinking (HED), use of illicit drugs, and socio-demographic background were assessed. Increased risk of casual sex in relation to time spent abroad vs. time spent in Sweden was analysed by a variant of case-crossover design. Factors that could be associated with increased risk of casual sex in Sweden and abroad, separately, were analysed by logistic regression.

Dental procedures, antibiotic prophylaxis, and endocarditis among people with prosthetic heart valves: nationwide population based cohort and a case crossover study

PubMed Central

Blotière, Pierre-Olivier; Hoen, Bruno; Lesclous, Philippe; Millot, Sarah; Rudant, Jérémie; Weill, Alain; Coste, Joel; Alla, François; Duval, Xavier

2017-01-01

Objective To assess the relation between invasive dental procedures and infective endocarditis associated with oral streptococci among people with prosthetic heart valves. Design Nationwide population based cohort and a case crossover study. Setting French national health insurance administrative data linked with the national hospital discharge database. Participants All adults aged more than 18 years, living in France, with medical procedure codes for positioning or replacement of prosthetic heart valves between July 2008 and July 2014. Main outcome measures Oral streptococcal infective endocarditis was identified using primary discharge diagnosis codes. In the cohort study, Poisson regression models were performed to estimate the rate of oral streptococcal infective endocarditis during the three month period after invasive dental procedures compared with non-exposure periods. In the case crossover study, conditional logistic regression models calculated the odds ratio and 95% confidence intervals comparing exposure to invasive dental procedures during the three month period preceding oral streptococcal infective endocarditis (case period) with three earlier control periods. Results The cohort included 138 876 adults with prosthetic heart valves (285 034 person years); 69 303 (49.9%) underwent at least one dental procedure. Among the 396 615 dental procedures performed, 103 463 (26.0%) were invasive and therefore presented an indication for antibiotic prophylaxis, which was performed in 52 280 (50.1%). With a median follow-up of 1.7 years, 267 people developed infective endocarditis associated with oral streptococci (incidence rate 93.7 per 100 000 person years, 95% confidence interval 82.4 to 104.9). Compared with non-exposure periods, no statistically significant increased rate of oral streptococcal infective endocarditis was observed during the three months after an invasive dental procedure (relative rate 1.25, 95% confidence interval 0.82 to 1.82; P=0.26) and after an invasive dental procedure without antibiotic prophylaxis (1.57, 0.90 to 2.53; P=0.08). In the case crossover analysis, exposure to invasive dental procedures was more frequent during case periods than during matched control periods (5.1% v 3.2%; odds ratio 1.66, 95% confidence interval 1.05 to 2.63; P=0.03). Conclusion Invasive dental procedures may contribute to the development of infective endocarditis in adults with prosthetic heart valves. PMID:28882817

Platelet aggregation inhibitors, vitamin K antagonists and risk of subarachnoid hemorrhage.

PubMed

Risselada, R; Straatman, H; van Kooten, F; Dippel, D W J; van der Lugt, A; Niessen, W J; Firouzian, A; Herings, R M C; Sturkenboom, M C J M

2011-03-01

Use of platelet aggregation inhibitors and vitamin K antagonists has been associated with an increased risk of intracranial hemorrhage (ICH). Whether the use of these antithrombotic drugs is associated with an increased risk of subarachnoid hemorrhage (SAH) remains unclear, especially as confounding by indication might play a role. The aim of the present study was to investigate whether use of platelet aggregation inhibitors or vitamin K antagonists increase the risk of SAH. We applied population-based case-control, case-crossover and case-time-control designs to estimate the risk of SAH while addressing issues both of confounding by indication and time varying exposure within the PHARMO Record Linkage System database. This system includes drug dispensing records from community pharmacies and hospital discharge records of more than 3 million community-dwelling inhabitants in the Netherlands. Patients were considered a case if they were hospitalized for a first SAH (ICD-9-CM code 430) in the period between 1st January 1998 and 31st December 2006. Controls were selected from the source population, matched on age, gender and date of hospitalization. Conditional logistic regression was used to estimate multivariable adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for the risk of SAH during use of platelet aggregation inhibitors or vitamin K antagonists. In the case-crossover and case-time-control designs we selected 11 control periods preceding the index date in successive steps of 1 month in the past. In all, 1004 cases of SAH were identified. In the case-control analysis the adjusted OR for the risk of SAH in current use of platelet aggregation inhibitors was 1.32 (95% CI: 1.02-1.70) and in current use of vitamin K antagonists 1.29 (95% CI: 0.89-1.87) compared with no use. In the case-crossover analysis the ORs for the risk of SAH in current use of platelet aggregation inhibitors and vitamin K antagonists were 1.04 (95% CI: 0.56-1.94) and 2.46 (95% CI: 1.04-5.82), respectively. In the case-time-control analysis the OR for platelet aggregation inhibitors was 0.50 (95% CI: 0.26-0.98) and for vitamin K antagonists 1.98 (95% CI: 0.82-4.76). The use of platelet aggregation inhibitors was not associated with an increased SAH risk; the modest increase observed in the case-control analysis could be as a result of confounding. The use of vitamin K antagonists seemed to be associated with an increased risk of SAH. The increase was most pronounced in the case-crossover analysis and therefore cannot be explained by unmeasured confounding. © 2011 International Society on Thrombosis and Haemostasis.

Balloon-Assisted Tracking Use Reduces Radial Artery Access Failure in an Experienced Radial Center and is Feasible During Primary PCI for STEMI.

PubMed

Obaid, Daniel; Hailan, Ahmed; Chase, Alexander; Dorman, Stephen; Jenkins, Geraint; Raybould, Adrian; Ramsey, Mark; Thomas, Phillip; Smith, David; Ionescu, Adrian

2017-07-01

This prospective study assesses balloon-assisted tracking (BAT) in reducing radial access failure during percutaneous coronary intervention (PCI). Arterial spasm prevents PCI from the radial artery in a small percentage of cases. A total of 2223 consecutive patients undergoing PCI from the radial approach were analyzed. Radial access failure mode and requirement for crossover to femoral access during a 12-month run-in period were compared with the following 14-month period with routine BAT usage. During the 14-month study period, 1334 radial PCIs were attempted. Twenty-six patients switched to femoral at an early stage, while 76 encountered radial spasm and underwent successful BAT in 69 cases (91%), giving a total crossover rate to femoral of 33/1334 (2.5%). Utilizing BAT rather than a femoral puncture reduced our institution's radial-femoral crossover rate from 7.6% to 2.5% (P<.01), which is also significantly lower than the radial-femoral crossover rate in the 12 months before BAT implementation (6.1%; P<.01). Mean procedure times were similar for those requiring BAT compared with conventional radial access (51.3 ± 21.3 min vs 47.9 ± 23.7 min; P=.23), and those crossing straight to femoral (BAT not attempted) (60.7 ± 31.9 min; P=.10). Mean first device/balloon time for the BAT-assisted primary PCI cases (22.6 ± 9.4 min) was similar to cases that had radial difficulties and converted to femoral without attempting BAT (25.8 ± 13.4 min; P=.54). BAT allowed catheter passage despite radial spasm in 91% of cases, significantly reducing the institution's rate of femoral crossover. During radial spasm in primary PCI, using BAT did not delay reperfusion compared with femoral crossover.

Development and evaluation of a study design typology for human research.

PubMed

Carini, Simona; Pollock, Brad H; Lehmann, Harold P; Bakken, Suzanne; Barbour, Edward M; Gabriel, Davera; Hagler, Herbert K; Harper, Caryn R; Mollah, Shamim A; Nahm, Meredith; Nguyen, Hien H; Scheuermann, Richard H; Sim, Ida

2009-11-14

A systematic classification of study designs would be useful for researchers, systematic reviewers, readers, and research administrators, among others. As part of the Human Studies Database Project, we developed the Study Design Typology to standardize the classification of study designs in human research. We then performed a multiple observer masked evaluation of active research protocols in four institutions according to a standardized protocol. Thirty-five protocols were classified by three reviewers each into one of nine high-level study designs for interventional and observational research (e.g., N-of-1, Parallel Group, Case Crossover). Rater classification agreement was moderately high for the 35 protocols (Fleiss' kappa = 0.442) and higher still for the 23 quantitative studies (Fleiss' kappa = 0.463). We conclude that our typology shows initial promise for reliably distinguishing study design types for quantitative human research.

Capacity Building in Response to Pandemic Influenza Threats: Lao PDR Case Study

PubMed Central

Phommasack, Bounlay; Moen, Ann; Vongphrachanh, Phengta; Tsuyuoka, Reiko; Cox, Nancy; Khamphaphongphanh, Bouaphanh; Phonekeo, Darouny; Kasai, Takeshi; Ketmayoon, Pakapak; Lewis, Hannah; Kounnavong, Bounheuang; Khanthamaly, Viengphone; Corwin, Andrew

2012-01-01

The Lao People's Democratic Republic (PDR) committed to pandemic detection and response preparations when faced with the threat of avian influenza. Since 2006, the National Center for Laboratory and Epidemiology of Lao PDR has developed credible laboratory, surveillance, and epidemiological (human) capacity and as a result was designated a World Health Organization National Influenza Center in 2010. The Lao PDR experience in building influenza capacities provides a case study of the considerable crossover effect of such investments to augment the capacity to combat emerging and re-emerging diseases other than influenza. PMID:23222137

The exposure-crossover design is a new method for studying sustained changes in recurrent events.

PubMed

Redelmeier, Donald A

2013-09-01

To introduce a new design that explores how an acute exposure might lead to a sustained change in the risk of a recurrent outcome. The exposure-crossover design uses self-matching to control within-person confounding due to genetics, personality, and all other stable patient characteristics. The design is demonstrated using population-based individual-level health data from Ontario, Canada, for three separate medical conditions (n > 100,000 for each) related to the risk of a motor vehicle crash (total outcomes, >2,000 for each). The exposure-crossover design yields numerical risk estimates during the baseline interval before an intervention, the induction interval immediately ahead of the intervention, and the subsequent interval after the intervention. Accompanying graphs summarize results, provide an intuitive display to readers, and show risk comparisons (absolute and relative). Self-matching increases statistical efficiency, reduces selection bias, and yields quantitative analyses. The design has potential limitations related to confounding, artifacts, pragmatics, survivor bias, statistical models, potential misunderstandings, and serendipity. The exposure-crossover design may help in exploring selected questions in epidemiology science. Copyright © 2013 Elsevier Inc. All rights reserved.

Control of Meiotic Crossovers: From Double-Strand Break Formation to Designation

PubMed Central

Gray, Stephen

2017-01-01

Meiosis, the mechanism of creating haploid gametes, is a complex cellular process observed across sexually reproducing organisms. Fundamental to meiosis is the process of homologous recombination, whereby DNA double-strand breaks are introduced into the genome and are subsequently repaired to generate either noncrossovers or crossovers. Although homologous recombination is essential for chromosome pairing during prophase I, the resulting crossovers are critical for maintaining homolog interactions and enabling accurate segregation at the first meiotic division. Thus, the placement, timing, and frequency of crossover formation must be exquisitely controlled. In this review, we discuss the proteins involved in crossover formation, the process of their formation and designation, and the rules governing crossovers, all within the context of the important landmarks of prophase I. We draw together crossover designation data across organisms, analyze their evolutionary divergence, and propose a universal model for crossover regulation. PMID:27648641

A Randomized Crossover Study of Web-Based Media Literacy to Prevent Smoking

ERIC Educational Resources Information Center

Shensa, Ariel; Phelps-Tschang, Jane; Miller, Elizabeth; Primack, Brian A.

2016-01-01

Feasibly implemented Web-based smoking media literacy (SML) programs have been associated with improving SML skills among adolescents. However, prior evaluations have generally had weak experimental designs. We aimed to examine program efficacy using a more rigorous crossover design. Seventy-two ninth grade students completed a Web-based SML…

Testing equality and interval estimation of the generalized odds ratio in ordinal data under a three-period crossover design.

PubMed

Lui, Kung-Jong; Chang, Kuang-Chao; Lin, Chii-Dean

2017-06-01

The crossover design can be of use to save the number of patients or improve power of a parallel groups design in studying treatments to noncurable chronic diseases. We propose using the generalized odds ratio for paired sample data to measure the relative effects in ordinal data between treatments and between periods. We show that one can apply the commonly used asymptotic and exact test procedures for stratified analysis in epidemiology to test non-equality of treatments in ordinal data, as well as obtain asymptotic and exact interval estimators for the generalized odds ratio under a three-period crossover design. We further show that one can apply procedures for testing the homogeneity of the odds ratio under stratified sampling to examine whether there are treatment-by-period interactions. We use the data taken from a three-period crossover trial studying the effects of low and high doses of an analgesic versus a placebo for the relief of pain in primary dysmenorrhea to illustrate the use of these test procedures and estimators proposed here.

Risk of injury after alcohol consumption from case-crossover studies in five countries from the America’s

PubMed Central

Borges, Guilherme; Orozco, Ricardo; Monteiro, Maristela; Cherpitel, Cheryl; Then, Eddy Pérez; López, Víctor A.; Bassier-Paltoo, Marcia; Weil A., Donald; de Bradshaw, Aldacira M

2012-01-01

Aims This study aimed to: 1) provide relative risk (RR) estimates between acute alcohol use and injuries from emergency departments in the Dominican Republic, Guatemala, Guyana, Nicaragua and Panama, and 2) test whether the RR differs if two control periods for the estimates were used. Design Case-crossover methodology was used to obtain estimates of the RR of having an injury within six hours after drinking alcohol, using a pair-matching design with control periods of the same time of day the day prior to injury, and the same time of day and day of week the week prior to injury. Setting Emergency departments(EDs). Participants 2,503 injured patients from EDs were interviewed between 2010–2011, with a response rate of 92.6%. Measurements Number of drinks consumed within six hours prior to the injury and in the two control periods. Findings The RR of injury after drinking alcohol was 4.38 (95% confidence interval CI= 3.29–5.84) using as the control period the prior week, and 5.35 (CI=3.50–8.17) using as a control period the prior day. The RR was 5.08 (CI=4.15–6.23) in multiple matching. Those drinking 1–2 drinks had a RR of 4.85 (CI=3.12–7.54); those drinking 3–5 a RR of 5.00 (CI =3.47–7.18); those drinking 6–15 a RR of 4.54 (CI=3.36–6.14); and those drinking 16 or more a RR of 10.42 (CI=4.38–24.79). Conclusions As in other countries, alcohol drinking is a trigger for an injury in all five countries. The use of more than one control period give further strength to these findings from case-crossover analysis. PMID:22775508

Single-case experimental design yielded an effect estimate corresponding to a randomized controlled trial.

PubMed

Shadish, William R; Rindskopf, David M; Boyajian, Jonathan G

2016-08-01

We reanalyzed data from a previous randomized crossover design that administered high or low doses of intravenous immunoglobulin (IgG) to 12 patients with hypogammaglobulinaemia over 12 time points, with crossover after time 6. The objective was to see if results corresponded when analyzed as a set of single-case experimental designs vs. as a usual randomized controlled trial (RCT). Two blinded statisticians independently analyzed results. One analyzed the RCT comparing mean outcomes of group A (high dose IgG) to group B (low dose IgG) at the usual trial end point (time 6 in this case). The other analyzed all 12 time points for the group B patients as six single-case experimental designs analyzed together in a Bayesian nonlinear framework. In the randomized trial, group A [M = 794.93; standard deviation (SD) = 90.48] had significantly higher serum IgG levels at time six than group B (M = 283.89; SD = 71.10) (t = 10.88; df = 10; P < 0.001), yielding a mean difference of MD = 511.05 [standard error (SE) = 46.98]. For the single-case experimental designs, the effect from an intrinsically nonlinear regression was also significant and comparable in size with overlapping confidence intervals: MD = 495.00, SE = 54.41, and t = 495.00/54.41 = 9.10. Subsequent exploratory analyses indicated that how trend was modeled made a difference to these conclusions. The results of single-case experimental designs accurately approximated results from an RCT, although more work is needed to understand the conditions under which this holds. Copyright © 2016 Elsevier Inc. All rights reserved.

Short-term effects of particulate matter on total mortality during Saharan dust outbreaks: a case-crossover analysis in Madrid (Spain).

PubMed

Tobías, Aurelio; Pérez, Laura; Díaz, Julio; Linares, Cristina; Pey, Jorge; Alastruey, Andrés; Querol, Xavier

2011-12-15

The role of Saharan dust outbreaks on the relationship between particulate matter and daily mortality has recently been addressed in studies conducted in Southern Europe, although they have not given consistent results. We investigated the effects of coarse (PM(10-2.5)) and fine particulate matter (PM(2.5)) in Madrid on total mortality during Saharan dust and non-dust days using a case-crossover design. During Saharan dust days, an increase of 10mg/m(3) of PM(10-2.5) raised total mortality by 2.8% compared with 0.6% during non-dust days (P-value for interaction=0.0165). We found evidence of stronger adverse health effects of PM(10-2.5) during Saharan dust outbreaks effects for impacted European populations, but not for PM(2.5). Further research is needed to understand mechanisms by which Saharan dust increases risk of mortality. Copyright © 2011 Elsevier B.V. All rights reserved.

Evaluating patient-reported outcome measurement comparability between paper and alternate versions, using the lung function questionnaire as an example.

PubMed

Dalal, Anand A; Nelson, Lauren; Gilligan, Theresa; McLeod, Lori; Lewis, Sandy; DeMuro-Mercon, Carla

2011-01-01

The goal of this study was to provide recommended steps to assess measurement comparability using a crossover study design and to demonstrate these steps using a short patient-reported outcome (PRO) instrument as an example. The example PRO instrument was administered via paper, Web, interactive voice response system, and interview; a randomized crossover design was used to gather data across the multiple administration types. Participants completed the PRO instrument, demographic and health questions, and a short preference questionnaire. Evaluation included comparisons of the item-level responses and agreement, comparison of mean scale scores, score classifications, and questions designed to collect usability and administration preference. Here the authors provide a four-step evaluation guide to evaluate measurement comparability and illustrate these steps using a case-finding tool. In the example, item-level kappa statistics between the paper and the alternate versions ranged from good to excellent, intraclass correlation coefficient for mean scores were above 0.70, and the rate of disagreement ranged from 2% to 14%. In addition, although participants had an administration preference, they reported few difficulties with the versions they were assigned. The steps described in this article provide a guide for evaluating whether to combine scores across administration versions to simplify analyses and interpretation under a crossover design. The guide recommends the investigation of item-level responses, summary scores, and participant usability/preference when comparing versions, with each step providing unique information to support comprehensive evaluation and informed decisions regarding whether to combine data. Copyright © 2011 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.

Tuning porosity and radial mechanical properties of DNA origami nanotubes via crossover design

NASA Astrophysics Data System (ADS)

Ma, Zhipeng; Kawai, Kentaro; Hirai, Yoshikazu; Tsuchiya, Toshiyuki; Tabata, Osamu

2017-06-01

DNA origami nanotubes are utilized as structural platforms for the fabrication of various micro/nanosystems for drug delivery, optical or biological sensing, and even nanoscale robots. Their radial structural and mechanical properties, which play a crucial role in the effective use of micro/nanosystems, have not been fully studied. In particular, the effects of crossovers, which are basic structures for rationally assembling double-stranded DNA (dsDNA) helices into a nanotube configuration, have not yet been characterized experimentally. To investigate the effects of crossovers on the porosity and the radial mechanical properties of DNA origami nanotubes, we fabricated a DNA origami nanotube with varied crossover designs along the nanotube axis. The radial geometry of the DNA origami nanotube is experimentally characterized by both atomic force microscopy (AFM) and electron cryomicroscopy (cryo-EM). Moreover, the radial mechanical properties of the DNA origami nanotube including the radial modulus are directly measured by force-distance-based AFM. These measurements reveal that the porosity and the radial modulus of DNA origami nanotubes can be tuned by adjusting the crossover design, which enables the optimal design and construction of DNA origami nanostructures for various applications.

Random-effects linear modeling and sample size tables for two special crossover designs of average bioequivalence studies: the four-period, two-sequence, two-formulation and six-period, three-sequence, three-formulation designs.

PubMed

Diaz, Francisco J; Berg, Michel J; Krebill, Ron; Welty, Timothy; Gidal, Barry E; Alloway, Rita; Privitera, Michael

2013-12-01

Due to concern and debate in the epilepsy medical community and to the current interest of the US Food and Drug Administration (FDA) in revising approaches to the approval of generic drugs, the FDA is currently supporting ongoing bioequivalence studies of antiepileptic drugs, the EQUIGEN studies. During the design of these crossover studies, the researchers could not find commercial or non-commercial statistical software that quickly allowed computation of sample sizes for their designs, particularly software implementing the FDA requirement of using random-effects linear models for the analyses of bioequivalence studies. This article presents tables for sample-size evaluations of average bioequivalence studies based on the two crossover designs used in the EQUIGEN studies: the four-period, two-sequence, two-formulation design, and the six-period, three-sequence, three-formulation design. Sample-size computations assume that random-effects linear models are used in bioequivalence analyses with crossover designs. Random-effects linear models have been traditionally viewed by many pharmacologists and clinical researchers as just mathematical devices to analyze repeated-measures data. In contrast, a modern view of these models attributes an important mathematical role in theoretical formulations in personalized medicine to them, because these models not only have parameters that represent average patients, but also have parameters that represent individual patients. Moreover, the notation and language of random-effects linear models have evolved over the years. Thus, another goal of this article is to provide a presentation of the statistical modeling of data from bioequivalence studies that highlights the modern view of these models, with special emphasis on power analyses and sample-size computations.

Interim analyses in 2 x 2 crossover trials.

PubMed

Cook, R J

1995-09-01

A method is presented for performing interim analyses in long term 2 x 2 crossover trials with serial patient entry. The analyses are based on a linear statistic that combines data from individuals observed for one treatment period with data from individuals observed for both periods. The coefficients in this linear combination can be chosen quite arbitrarily, but we focus on variance-based weights to maximize power for tests regarding direct treatment effects. The type I error rate of this procedure is controlled by utilizing the joint distribution of the linear statistics over analysis stages. Methods for performing power and sample size calculations are indicated. A two-stage sequential design involving simultaneous patient entry and a single between-period interim analysis is considered in detail. The power and average number of measurements required for this design are compared to those of the usual crossover trial. The results indicate that, while there is minimal loss in power relative to the usual crossover design in the absence of differential carry-over effects, the proposed design can have substantially greater power when differential carry-over effects are present. The two-stage crossover design can also lead to more economical studies in terms of the expected number of measurements required, due to the potential for early stopping. Attention is directed toward normally distributed responses.

Genetic-evolution-based optimization methods for engineering design

NASA Technical Reports Server (NTRS)

Rao, S. S.; Pan, T. S.; Dhingra, A. K.; Venkayya, V. B.; Kumar, V.

1990-01-01

This paper presents the applicability of a biological model, based on genetic evolution, for engineering design optimization. Algorithms embodying the ideas of reproduction, crossover, and mutation are developed and applied to solve different types of structural optimization problems. Both continuous and discrete variable optimization problems are solved. A two-bay truss for maximum fundamental frequency is considered to demonstrate the continuous variable case. The selection of locations of actuators in an actively controlled structure, for minimum energy dissipation, is considered to illustrate the discrete variable case.

Associations between ambient air pollution and daily mortality in a cohort of congestive heart failure: Case-crossover and nested case-control analyses using a distributed lag nonlinear model.

PubMed

Buteau, Stephane; Goldberg, Mark S; Burnett, Richard T; Gasparrini, Antonio; Valois, Marie-France; Brophy, James M; Crouse, Dan L; Hatzopoulou, Marianne

2018-04-01

Persons with congestive heart failure may be at higher risk of the acute effects related to daily fluctuations in ambient air pollution. To meet some of the limitations of previous studies using grouped-analysis, we developed a cohort study of persons with congestive heart failure to estimate whether daily non-accidental mortality were associated with spatially-resolved, daily exposures to ambient nitrogen dioxide (NO 2 ) and ozone (O 3 ), and whether these associations were modified according to a series of indicators potentially reflecting complications or worsening of health. We constructed the cohort from the linkage of administrative health databases. Daily exposure was assigned from different methods we developed previously to predict spatially-resolved, time-dependent concentrations of ambient NO 2 (all year) and O 3 (warm season) at participants' residences. We performed two distinct types of analyses: a case-crossover that contrasts the same person at different times, and a nested case-control that contrasts different persons at similar times. We modelled the effects of air pollution and weather (case-crossover only) on mortality using distributed lag nonlinear models over lags 0 to 3 days. We developed from administrative health data a series of indicators that may reflect the underlying construct of "declining health", and used interactions between these indicators and the cross-basis function for air pollutant to assess potential effect modification. The magnitude of the cumulative as well as the lag-specific estimates of association differed in many instances according to the metric of exposure. Using the back-extrapolation method, which is our preferred exposure model, we found for the case-crossover design a cumulative mean percentage changes (MPC) in daily mortality per interquartile increment in NO 2 (8.8 ppb) of 3.0% (95% CI: -0.9, 6.9%) and for O 3 (16.5 ppb) 3.5% (95% CI: -4.5, 12.1). For O 3 there was strong confounding by weather (unadjusted MPC = 7.1%; 95% CI: 1.7, 12.7%). For the nested case-control approach the cumulative MPC for NO 2 in daily mortality was 2.9% (95% CI: -0.9, 6.9%) and for O 3 7.3% (95% CI: 3.0, 11.9%). We found evidence of effect modification between daily mortality and cumulative NO 2 and O 3 according to the prescribed dose of furosemide in the nested case-control analysis, but not in the case-crossover analysis. Mortality in congestive heart failure was associated with exposure to daily ambient NO 2 and O 3 predicted from a back-extrapolation method using a land use regression model from dense sampling surveys. The methods used to assess exposure can have considerable influence on the estimated acute health effects of the two air pollutants. Copyright © 2018 Elsevier Ltd. All rights reserved.

The assessment of health policy changes using the time-reversed crossover design.

PubMed Central

Sollecito, W A; Gillings, D B

1986-01-01

The time-reversed crossover design is a quasi-experimental design which can be applied to evaluate the impact of a change in health policy on a large population. This design makes use of separate sampling and analysis strategies to improve the validity of conclusions drawn from such an evaluation. The properties of the time-reversed crossover design are presented including the use of stratification on outcome in the sampling stage, which is intended to improve external validity. It is demonstrated that, although this feature of the design introduces internal validity threats due to regression toward the mean in extreme-outcome strata, these effects can be measured and eliminated from the test of significance of treatment effects. Methods for within- and across-stratum estimation and hypothesis-testing are presented which are similar to those which have been developed for the traditional two-period crossover design widely used in clinical trials. The procedures are illustrated using data derived from a study conducted by the United Mine Workers of America Health and Retirement Funds to measure the impact of cost-sharing on health care utilization among members of its health plan. PMID:3081465

Electromagnetic pump stator frame having power crossover struts

DOEpatents

Fanning, Alan W.; Olich, Eugene E.

1995-01-01

A stator frame for an electromagnetic pump includes a casing joined to a hub by a plurality of circumferentially spaced apart struts. At least one electrically insulated power crossover lead extends through the hub, through a crossover one of the struts, and through the casing for carrying electrical current therethrough.

A comparison of estimators from self-controlled case series, case-crossover design, and sequence symmetry analysis for pharmacoepidemiological studies.

PubMed

Takeuchi, Yoshinori; Shinozaki, Tomohiro; Matsuyama, Yutaka

2018-01-08

Despite the frequent use of self-controlled methods in pharmacoepidemiological studies, the factors that may bias the estimates from these methods have not been adequately compared in real-world settings. Here, we comparatively examined the impact of a time-varying confounder and its interactions with time-invariant confounders, time trends in exposures and events, restrictions, and misspecification of risk period durations on the estimators from three self-controlled methods. This study analyzed self-controlled case series (SCCS), case-crossover (CCO) design, and sequence symmetry analysis (SSA) using simulated and actual electronic medical records datasets. We evaluated the performance of the three self-controlled methods in simulated cohorts for the following scenarios: 1) time-invariant confounding with interactions between the confounders, 2) time-invariant and time-varying confounding without interactions, 3) time-invariant and time-varying confounding with interactions among the confounders, 4) time trends in exposures and events, 5) restricted follow-up time based on event occurrence, and 6) patient restriction based on event history. The sensitivity of the estimators to misspecified risk period durations was also evaluated. As a case study, we applied these methods to evaluate the risk of macrolides on liver injury using electronic medical records. In the simulation analysis, time-varying confounding produced bias in the SCCS and CCO design estimates, which aggravated in the presence of interactions between the time-invariant and time-varying confounders. The SCCS estimates were biased by time trends in both exposures and events. Erroneously short risk periods introduced bias to the CCO design estimate, whereas erroneously long risk periods introduced bias to the estimates of all three methods. Restricting the follow-up time led to severe bias in the SSA estimates. The SCCS estimates were sensitive to patient restriction. The case study showed that although macrolide use was significantly associated with increased liver injury occurrence in all methods, the value of the estimates varied. The estimations of the three self-controlled methods depended on various underlying assumptions, and the violation of these assumptions may cause non-negligible bias in the resulting estimates. Pharmacoepidemiologists should select the appropriate self-controlled method based on how well the relevant key assumptions are satisfied with respect to the available data.

Air pollution exposure--a trigger for myocardial infarction?

PubMed

Berglind, Niklas; Ljungman, Petter; Möller, Jette; Hallqvist, Johan; Nyberg, Fredrik; Rosenqvist, Mårten; Pershagen, Göran; Bellander, Tom

2010-04-01

The association between ambient air pollution exposure and hospitalization for cardiovascular events has been reported in several studies with conflicting results. A case-crossover design was used to investigate the effects of air pollution in 660 first-time myocardial infarction cases in Stockholm in 1993-1994, interviewed shortly after diagnosis using a standard protocol. Air pollution data came from central urban background monitors. No associations were observed between the risk for onset of myocardial infarction and two-hour or 24-hour air pollution exposure. No evidence of susceptible subgroups was found. This study provides no support that moderately elevated air pollution levels trigger first-time myocardial infarction.

Procedures for assessing psychological predictors of injuries in circus artists: a pilot prospective study.

PubMed

Shrier, Ian; Raglin, John S; Levitan, Emily B; Mittleman, Murray A; Steele, Russell J; Powell, Janette

2014-06-11

Research on psychological risk factors for injury has focused on stable traits. Our objective was to test the feasibility of a prospective longitudinal study designed to examine labile psychological states as risk factors of injury. We measured psychological traits at baseline (mood, ways of coping and anxiety), and psychological states every day (1-item questions on anxiety, sleep, fatigue, soreness, self-confidence) before performances in Cirque du Soleil artists of the show "O". Additional questions were added once per week to better assess anxiety (20-item) and mood. Questionnaires were provided in English, French, Russian and Japanese. Injury and exposure data were extracted from electronic records that are kept as part of routine business practices. The 43.9% (36/82) recruitment rate was more than expected. Most artists completed the baseline questionnaires in 15 min, a weekly questionnaire in <2 min and a daily questionnaire in <1 min. We improved the formatting of some questions during the study, and adapted the wording of other questions to improve clarity. There were no dropouts during the entire study, suggesting the questionnaires were appropriate in content and length. Results for sample size calculations depend on the number of artists followed and the minimal important difference in injury rates, but in general, preclude a purely prospective study with daily data collection because of the long follow-up required. However, a prospective nested case-crossover design with data collection bi-weekly and at the time of injury appears feasible. A prospective study collecting psychological state data from subjects who train and work regularly together is feasible, but sample size calculations suggest that the optimal study design would use prospective nested case-crossover methodology.

Procedures for assessing psychological predictors of injuries in circus artists: a pilot prospective study

PubMed Central

2014-01-01

Background Research on psychological risk factors for injury has focused on stable traits. Our objective was to test the feasibility of a prospective longitudinal study designed to examine labile psychological states as risk factors of injury. Methods We measured psychological traits at baseline (mood, ways of coping and anxiety), and psychological states every day (1-item questions on anxiety, sleep, fatigue, soreness, self-confidence) before performances in Cirque du Soleil artists of the show “O”. Additional questions were added once per week to better assess anxiety (20-item) and mood. Questionnaires were provided in English, French, Russian and Japanese. Injury and exposure data were extracted from electronic records that are kept as part of routine business practices. Results The 43.9% (36/82) recruitment rate was more than expected. Most artists completed the baseline questionnaires in 15 min, a weekly questionnaire in <2 min and a daily questionnaire in <1 min. We improved the formatting of some questions during the study, and adapted the wording of other questions to improve clarity. There were no dropouts during the entire study, suggesting the questionnaires were appropriate in content and length. Results for sample size calculations depend on the number of artists followed and the minimal important difference in injury rates, but in general, preclude a purely prospective study with daily data collection because of the long follow-up required. However, a prospective nested case-crossover design with data collection bi-weekly and at the time of injury appears feasible. Conclusion A prospective study collecting psychological state data from subjects who train and work regularly together is feasible, but sample size calculations suggest that the optimal study design would use prospective nested case-crossover methodology. PMID:24920527

Testing for carryover effects after cessation of treatments: a design approach.

PubMed

Sturdevant, S Gwynn; Lumley, Thomas

2016-08-02

Recently, trials addressing noisy measurements with diagnosis occurring by exceeding thresholds (such as diabetes and hypertension) have been published which attempt to measure carryover - the impact that treatment has on an outcome after cessation. The design of these trials has been criticised and simulations have been conducted which suggest that the parallel-designs used are not adequate to test this hypothesis; two solutions are that either a differing parallel-design or a cross-over design could allow for diagnosis of carryover. We undertook a systematic simulation study to determine the ability of a cross-over or a parallel-group trial design to detect carryover effects on incident hypertension in a population with prehypertension. We simulated blood pressure and focused on varying criteria to diagnose systolic hypertension. Using the difference in cumulative incidence hypertension to analyse parallel-group or cross-over trials resulted in none of the designs having acceptable Type I error rate. Under the null hypothesis of no carryover the difference is well above the nominal 5 % error rate. When a treatment is effective during the intervention period, reliable testing for a carryover effect is difficult. Neither parallel-group nor cross-over designs using the difference in cumulative incidence appear to be a feasible approach. Future trials should ensure their design and analysis is validated by simulation.

Methods to control for unmeasured confounding in pharmacoepidemiology: an overview.

PubMed

Uddin, Md Jamal; Groenwold, Rolf H H; Ali, Mohammed Sanni; de Boer, Anthonius; Roes, Kit C B; Chowdhury, Muhammad A B; Klungel, Olaf H

2016-06-01

Background Unmeasured confounding is one of the principal problems in pharmacoepidemiologic studies. Several methods have been proposed to detect or control for unmeasured confounding either at the study design phase or the data analysis phase. Aim of the Review To provide an overview of commonly used methods to detect or control for unmeasured confounding and to provide recommendations for proper application in pharmacoepidemiology. Methods/Results Methods to control for unmeasured confounding in the design phase of a study are case only designs (e.g., case-crossover, case-time control, self-controlled case series) and the prior event rate ratio adjustment method. Methods that can be applied in the data analysis phase include, negative control method, perturbation variable method, instrumental variable methods, sensitivity analysis, and ecological analysis. A separate group of methods are those in which additional information on confounders is collected from a substudy. The latter group includes external adjustment, propensity score calibration, two-stage sampling, and multiple imputation. Conclusion As the performance and application of the methods to handle unmeasured confounding may differ across studies and across databases, we stress the importance of using both statistical evidence and substantial clinical knowledge for interpretation of the study results.

Rhombic-Shaped Nanostructures and Mechanical Properties of 2D DNA Origami Constructed with Different Crossover/Nick Designs.

PubMed

Ma, Zhipeng; Huang, Yunfei; Park, Seongsu; Kawai, Kentaro; Kim, Do-Nyun; Hirai, Yoshikazu; Tsuchiya, Toshiyuki; Yamada, Hirofumi; Tabata, Osamu

2018-01-01

DNA origami methods enable the fabrication of various nanostructures and nanodevices, but their effective use depends on an understanding of their structural and mechanical properties and the effects of basic structural features. Frequency-modulation atomic force microscopy is introduced to directly characterize, in aqueous solution, the crossover regions of sets of 2D DNA origami based on different crossover/nick designs. Rhombic-shaped nanostructures formed under the influence of flexible crossovers placed between DNA helices are observed in DNA origami incorporating crossovers every 3, 4, or 6 DNA turns. The bending rigidity of crossovers is determined to be only one-third of that of the DNA helix, based on interhelical electrostatic forces reported elsewhere, and the measured pitches of the 3-turn crossover design rhombic-shaped nanostructures undergoing negligible bending. To evaluate the robustness of their structural integrity, they are intentionally and simultaneously stressed using force-controlled atomic force microscopy. DNA crossovers are verified to have a stabilizing effect on the structural robustness, while the nicks have an opposite effect. The structural and mechanical properties of DNA origami and the effects of crossovers and nicks revealed in this paper can provide information essential for the design of versatile DNA origami structures that exhibit specified and desirable properties. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Rushing, distraction, walking on contaminated floors and risk of slipping in limited-service restaurants: a case--crossover study.

PubMed

Verma, Santosh K; Lombardi, David A; Chang, Wen Ruey; Courtney, Theodore K; Huang, Yueng-Hsiang; Brennan, Melanye J; Mittleman, Murray A; Ware, James H; Perry, Melissa J

2011-08-01

This nested case-crossover study examined the association between rushing, distraction and walking on a contaminated floor and the rate of slipping, and whether the effects varied according to weekly hours worked, job tenure and use of slip-resistant shoes. At baseline, workers from 30 limited-service restaurants in the USA reported average work hours, average weekly duration of exposure to each transient risk factor and job tenure at the current location. Use of slip-resistant shoes was determined. During the following 12 weeks, participants reported weekly their slip experience and exposures to the three transient exposures at the time of slipping. The case-crossover design was used to estimate the rate ratios using the Mantel-Haenszel estimator for person-time data. Among 396 participants providing baseline information, 210 reported one or more slips with a total of 989 slips. Rate of slipping was 2.9 times higher when rushing as compared to working at a normal pace (95% CI 2.5 to 3.3). Rate of slipping was also significantly increased by distraction (rate ratio (RR) 1.7, 95% CI 1.5 to 2.0) and walking on a contaminated floor (RR 14.6, 95% CI 12.6 to 17.0). Use of slip-resistant shoes decreased the effects of rushing and walking on a contaminated floor. Rate ratios for all three transient factors decreased monotonically as job tenure increased. The results suggest the importance of these transient risk factors, particularly floor contamination, on rate of slipping in limited-service restaurant workers. Stable characteristics, such as slip-resistant shoes, reduced the effects of transient exposures.

Landing Mechanics During Side Hopping and Crossover Hopping Maneuvers in Noninjured Women and Women With Anterior Cruciate Ligament Reconstruction

PubMed Central

Ortiz, Alexis; Olson, Sharon; Trudelle-Jackson, Elaine; Rosario, Martin; Venegas, Heidi L.

2011-01-01

Objective To compare, landing mechanics and electromyographic activity of the lower extremities during side hopping and crossover hopping maneuvers, in noninjured women and women with anterior cruciate ligament (ACL) reconstruction. Design A case-control study. Setting A 3-dimensional motion analysis laboratory. Participants Twenty-eight young women (range, 21–35 years) (15 control subjects and 13 subjects with ACL reconstruction). Patients and Methods All participants performed a side-to-side hopping task that consisted of hopping single-legged 10 times consecutively from side to side across 2 lines marked 30 cm apart on 2 individual force plates. The task was designated as a side hopping when the hop was to the opposite side of the stance leg and as crossover hopping when the hop was toward the side of the stance leg. Main Outcome Measurements Peak hip-/knee-joint angles; peak knee extension/abduction joint moments; electromyographic studies of the gluteus maximus, gluteus medius, rectus femoris, and hamstring muscles; and quadriceps/hamstring co-contraction ratio were compared between the groups by means of 2 × 2 multivariate analysis of variance tests (group × maneuver). Results Noninjured women and women with ACL reconstruction exhibited similar hip-and knee-joint angles during both types of hopping. Hip-joint angles were greater during the crossover hopping in both groups, and knee-joint angles did not differ between the groups or hops. Knee-joint moments demonstrated a significant group × maneuver interaction. Greater knee extension and valgus moments were noted in the control group during crossover hopping, and greater knee abduction moments were noted in the ACL group during side hopping. Electromyographic data revealed no statistically significantly differences between the groups. Conclusions Women with ACL reconstruction exhibited the restoration of functional biomechanical movements such as hip-/knee-joint angles and lower extremity neuromuscular activation during side-to-side athletic tasks. However, not all biomechanical strategies are restored years after surgery, and women who have undergone a procedure such as ACL reconstruction may continue to exhibit knee-joint abduction moments that increase the risk of additional knee injury. PMID:21257128

Is perceived failure in school performance a trigger of physical injury? A case-crossover study of children in Stockholm County

PubMed Central

Laflamme, L; Engstrom, K; Moller, J; Hallqvist, J

2004-01-01

Objectives: To investigate whether perceived failure in school performance increases the potential for children to be physically injured. Subjects: Children aged 10–15 years residing in the Stockholm County and hospitalised or called back for a medical check up because of a physical injury during the school years 2000–2001 and 2001–2002 (n = 592). Methods: A case-crossover design was used and information on potential injury triggers was gathered by interview. Information about family socioeconomic circumstances was gathered by a questionnaire filled in by parents during the child interview (response rate 87%). Results: Perceived failure in school performance has the potential to trigger injury within up to 10 hours subsequent to exposure (relative risk = 2.70; 95% confidence intervals = 1.2 to 5.8). The risk is significantly higher among pre-adolescents and among children from families at a higher education level. Conclusions: Experiencing feelings of failure may affect children's physical safety, in particular among pre-adolescents. Possible mechanisms are perceptual deficits and response changes occasioned by the stress experienced after exposure. PMID:15082740

Exposure to air pollutants and mortality in hypertensive patients according to demography: a 10 year case-crossover study.

PubMed

Wong, Martin C S; Tam, Wilson W S; Wang, Harry H X; Lao, X Q; Zhang, Daisy Dexing; Chan, Sky W M; Kwan, Mandy W M; Fan, Carmen K M; Cheung, Clement S K; Tong, Ellen L H; Cheung, N T; Tse, L A; Yu, Ignatius T S

2014-09-01

This study evaluated whether short term exposures to NO2, O3, particulate matter <10 mm in diameter (PM10) were associated with higher risk of mortality. A total of 223,287 hypertensive patients attended public health-care services and newly prescribed at least 1 antihypertensive agent were followed-up for up to 5 years. A time-stratified, bi-directional case-crossover design was adopted. For all-cause mortality, significant positive associations were observed for NO2 and PM10 at lag 0-3 days per 10 μg/m(3) increase in concentration (excess risks 1.187%-2.501%). Significant positive associations were found for O3 at lag 1 and 2 days and the excess risks were 1.654% and 1.207%, respectively. We found similarly positive associations between these pollutants and respiratory disease mortality. These results were significant among those aged ≥65 years and in cold seasons only. Older hypertensive patients are susceptible to all-cause and respiratory disease-specific deaths from these air pollutants in cold weather. Copyright © 2014 Elsevier Ltd. All rights reserved.

Hypnosis and Local Anesthesia for Dental Pain Relief-Alternative or Adjunct Therapy?-A Randomized, Clinical-Experimental Crossover Study.

PubMed

Wolf, Thomas Gerhard; Wolf, Dominik; Callaway, Angelika; Below, Dagna; d'Hoedt, Bernd; Willershausen, Brita; Daubländer, Monika

2016-01-01

This prospective randomized clinical crossover trial was designed to compare hypnosis and local anesthesia for experimental dental pain relief. Pain thresholds of the dental pulp were determined. A targeted standardized pain stimulus was applied and rated on the Visual Analogue Scale (0-10). The pain threshold was lower under hypnosis (58.3 ± 17.3, p < .001), maximal (80.0) under local anesthesia. The pain stimulus was scored higher under hypnosis (3.9 ± 3.8) than with local anesthesia (0.0, p < .001). Local anesthesia was superior to hypnosis and is a safe and effective method for pain relief in dentistry. Hypnosis seems to produce similar effects observed under sedation. It can be used in addition to local anesthesia and in individual cases as an alternative for pain control in dentistry.

Gaseous Air Pollution and the Risk for Stroke Admissions: A Case-Crossover Study in Beijing, China.

PubMed

Huang, Fangfang; Luo, Yanxia; Tan, Peng; Xu, Qin; Tao, Lixin; Guo, Jin; Zhang, Feng; Xie, Xueqin; Guo, Xiuhua

2017-02-14

Background: Though increasing evidence supports association between gaseous air pollution and stroke, it remains unclear whether the effects differ in season, sex and age. The aim of this study was to examine the associations of gaseous air pollution with stroke admissions in Beijing, 2013-2014 in different subgroups. Methods: Case-crossover design and conditional logistic regression were used to perform the analyses. We examined the exposure-response relationship between air pollution and stroke. Stratified analyses were performed in different seasons, sex, and age groups. Results: There were 147,624 stroke admissions during the study period. In the whole study period, percent changes of stroke admissions were 0.82% (95% CI: 0.52% to 1.13%) and 0.73% (95% CI: 0.44% to 1.03%) per 10 μg/m³ increase in the same day conentration of nitrogen dioxide (NO₂) and sulfur dioxide (SO₂). The positive associations were higher in warm seasons and with patients >65 years ( p < 0.05). Contrary effects of carbon monoxide (CO) and ozone on stroke admissions were observed in different seasons. Conclusions: NO₂ and SO₂ were positively associated with stroke admissions, with stronger effects in warm seasons and with patients >65 years. The associations of CO and ozone with stroke admissions differed across seasons.

Transient effects of transfusion and feeding advances (volumetric and caloric) on necrotizing enterocolitis development: A case-crossover study.

PubMed

Le, Vi T; Klebanoff, Mark A; Talavera, Maria M; Slaughter, Jonathan L

2017-01-01

To evaluate the short-term effects of feed fortification, feed volume increase, and PRBC transfusion on the odds of developing NEC. Case-crossover study of neonatal intensive care infants born at ≤ 32 weeks' gestation who were admitted to 5 central Ohio intensive care units from January 2012-July 2016 and developed NEC Bell Stage ≥2. Each patient served as their own control, with exposure during the 48-hour period just prior to NEC onset (hazard period) being compared to a preceding 48-hour control period, thus eliminating confounding by patient factors fixed between both intervals. NEC onset was determined by chart review as the earliest occurrence of one of the following within 24 hours of confirmatory x-ray: (1) antibiotic initiation, (2) enteral feeding cessation, (3) physician first notified of abdominal concerns, or (4) abdominal x-ray ordered. Conditional logistic regression compared exposures to feed volume increase, fortification, and PRBC transfusion during the 48-hour period prior to NEC onset to those during a preceding 48-hour control period. Analyses were stratified by gestational age and anemia (defined: hemoglobin ≤ 9.3 g/dL within 7 days of NEC onset). We included 63 infants with confirmed NEC. Acute exposure to fortification (odds ratio [OR]: 1.67, 95% confidence interval [CI]: 0.61, 4.59), feed volume increase (OR: 0.63, 95% CI: 0.28, 1.38), and PRBC transfusion (OR: 1.80, 95% CI: 0.60, 5.37) was not associated with the onset of NEC. Gestational age and anemia did not significantly modify the associations. Sensitivity testing substituting 24- and 72-hour hazard and control periods produced similar results. Using a case-crossover design, we did not detect an association between NEC development and feed fortification, feed volume increase, or PRBC transfusion within 48-hours prior to NEC-onset. Replication in a larger set of cases is needed.

Short-term use of glucocorticoids and risk of peptic ulcer bleeding: a nationwide population-based case-crossover study.

PubMed

Tseng, C-L; Chen, Y-T; Huang, C-J; Luo, J-C; Peng, Y-L; Huang, D-F; Hou, M-C; Lin, H-C; Lee, F-Y

2015-09-01

Controversy exists regarding glucocorticoids therapy and the risk of peptic ulcer bleeding (PUB). The present study was undertaken to determine whether short-term use of glucocorticoids is associated with the occurrence of peptic ulcer bleeding. The records of adult patients hospitalised for newly diagnosed peptic ulcer bleeding from 2000 to 2012 were retrieved from the Taiwan National Health Insurance Research Database, a nationwide population-based registry system. The association between systemic glucocorticoids usage and peptic ulcer bleeding was determined with a conditional logistic regression model comparing cases and controls during time windows of 7, 14 and 28 days using a case-crossover design. Of the 8894 enrolled patients, the adjusted self-matched odds ratios for peptic ulcer bleeding after exposure to the glucocorticoids were 1.37 (95% CI: 1.12-1.68, P = 0.003) for the 7-day window, 1.66 (95% CI: 1.38-2.00, P < 0.001) for the 14-day window and 1.84 (95% CI: 1.57-2.16, P < 0.001) for the 28-day window. Moderate to high, but not low dose glucocorticoids (methylprednisolone <4 mg/day or its equivalence) were associated with an increased risk of peptic ulcer bleeding. Concomitant use of a nonselective nonsteroidal anti-inflammatory drug (NSAID) or aspirin further elevated the risk. However, it does not eliminate the effect of underlying diseases flare-up that may have placed the patients at risk for peptic ulcer bleeding in this kind of study design. Short-term (7-28 days) exposure to glucocorticoids is significantly associated with peptic ulcer bleeding; this risk seems dose-dependent and is higher when nonselective NSAIDs or aspirin are used concurrently. © 2015 John Wiley & Sons Ltd.

Emotional stress as a trigger of falls leading to hip or pelvic fracture. Results from the ToFa study - a case-crossover study among elderly people in Stockholm, Sweden.

PubMed

Möller, Jette; Hallqvist, Johan; Laflamme, Lucie; Mattsson, Fredrik; Ponzer, Sari; Sadigh, Siv; Engström, Karin

2009-02-09

Sudden emotions may interfere with mechanisms for keeping balance among the elderly. The aim of this study is to analyse if emotional stress and specifically feelings of anger, sadness, worries, anxiety or stress, can trigger falls leading to hip or pelvic fracture among autonomous older people. The study applied the case-crossover design and was based on data gathered by face to face interviews carried out in Stockholm between November 2004 and January 2006 at the emergency wards of two hospitals. Cases (n = 137) were defined as persons aged 65 and older admitted for at least one night due to a fall-related hip or pelvic fracture (ICD10: S72 or S32) and meeting a series of selection criteria. Results are presented as relative risks with 95% confidence intervals. There was an increased risk for fall and subsequent hip or pelvic fracture for up to one hour after emotional stress. For anger there was an increased relative risk of 12.2 (95% CI 2.7-54.7), for sadness of 5.7 (95% CI 1.1-28.7), and for stress 20.6 (95% CI 4.5-93.5) compared to periods with no such feelings. Emotional stress seems to have the potential to trigger falls and subsequent hip or pelvic fracture among autonomous older people. Further studies are needed to clarify how robust the findings are - as the number of exposed cases is small - and the mechanisms behind them - presumably balance and vision impairment in stress situation.

Air pollution and asthma attacks in children: A case-crossover analysis in the city of Chongqing, China.

PubMed

Ding, Ling; Zhu, Daojuan; Peng, Donghong; Zhao, Yao

2017-01-01

Data on particulate matter of diameter <2.5 μm (PM 2.5 ) in the city of Chongqing were first announced in 2013. We wished to assess the effects of pollutants on asthmatic children in Chongqing, China. Daily numbers of hospital visits because of asthma attacks in children aged 0-18 years in 2013 were collected from the Children's Hospital of Chongqing Medical University. Data on pollutants were accessed from the nine air quality-monitoring stations in Chongqing. A time-stratified case-crossover design was applied and conditional logistic regression was undertaken to analyze the data. We found that short-term exposure to PM 10 , PM 2.5 , sodium dioxide, nitrogen and carbon monoxide could trigger hospital visits for asthma in children. Nitrogen dioxide had an important role, whereas ozone had no effect. Copyright © 2016 Elsevier Ltd. All rights reserved.

Robustness of crossover trials against subject drop-out - Examples of perpetually connected designs.

PubMed

Godolphin, P J; Godolphin, E J

2017-01-01

When performing a repeated measures experiment, such as a clinical trial, there is a risk of subject drop-out during the experiment. If one or more subjects leave the study prematurely, a situation could arise where the eventual design is disconnected, implying that very few treatment contrasts for both direct effects and carryover effects are estimable. This paper aims to identify experimental conditions where this problem with the eventual design can be avoided. It is shown that in the class of uniformly balanced repeated measurement designs consisting of two or more Latin squares, there are planned designs with the following useful property. Provided that all subjects have completed the first two periods of study, such a design will not be replaced by a disconnected eventual design due to drop-out, irrespective of the type of drop-out behaviour that may occur. Designs with this property are referred to as perpetually connected. These experimental conditions are identified and examined in the paper and an example of at least one perpetually connected uniformly balanced repeated measurement design is given in each case. The results improve upon previous contributions in the literature that have been confined largely to cases in which drop-out occurs only in the final periods of study.

Is ambient air pollution associated with onset of sudden infant death syndrome: a case-crossover study in the UK

PubMed Central

Ayres, Jon G; Mohammed, Nuredin I

2018-01-01

Objectives Air pollution has been associated with increased mortality and morbidity in several studies with indications that its effect could be more severe in children. This study examined the relationship between short-term variations in criteria air pollutants and occurrence of sudden infant death syndrome (SIDS). Design We used a case-crossover study design which is widely applied in air pollution studies and particularly useful for estimating the risk of a rare acute outcome associated with short-term exposure. Setting The study used data from the West Midlands region in the UK. Participants We obtained daily time series data on SIDS mortality (ICD-9: 798.0 or ICD-10: R95) for the period 1996–2006 with a total of 211 SIDS events. Primary outcome measures Daily counts of SIDS events. Results For an IQR increase in previous day pollutant concentration, the percentage increases (95% CI) in SIDS were 16 (6 to 27) for PM10, 1 (−7 to 10) for SO2, 5 (−4 to 14) for CO, −17 (−27 to –6) for O3, 16 (2 to 31) for NO2 and 2 (−3 to 8) for NO after controlling for average temperature and national holidays. PM10 and NO2 showed relatively consistent association which persisted across different lag structures and after adjusting for copollutants. Conclusions The results indicated ambient air pollutants, particularly PM10 and NO2, may show an association with increased SIDS mortality. Thus, future studies are recommended to understand possible mechanistic explanations on the role of air pollution on SIDS incidence and the ways in which we might reduce pollution exposure among infants. PMID:29654005

Randomized crossover clinical trial of real and sham peripheral prism glasses for hemianopia.

PubMed

Bowers, Alex R; Keeney, Karen; Peli, Eli

2014-02-01

There is a major lack of randomized controlled clinical trials evaluating the efficacy of prismatic treatments for hemianopia. Evidence for their effectiveness is mostly based on anecdotal case reports and open-label evaluations without a control condition. To evaluate the efficacy of real relative to sham peripheral prism glasses for patients with complete homonymous hemianopia. Double-masked, randomized crossover trial at 13 study sites, including the Peli laboratory at Schepens Eye Research Institute, 11 vision rehabilitation clinics in the United States, and 1 in the United Kingdom. Patients were 18 years or older with complete homonymous hemianopia for at least 3 months and without visual neglect or significant cognitive decline. Patients were allocated by minimization into 2 groups. One group received real (57-prism diopter) oblique and sham (<5-prism diopter) horizontal prisms; the other received real horizontal and sham oblique, in counterbalanced order. Each crossover period was 4 weeks. The primary outcome was the overall difference, across the 2 periods of the crossover, between the proportion of participants who wanted to continue with (said yes to) real prisms and the proportion who said yes to sham prisms. The secondary outcome was the difference in perceived mobility improvement between real and sham prisms. Of 73 patients randomized, 61 completed the crossover. A significantly higher proportion said yes to real than sham prisms (64% vs 36%; odds ratio, 5.3; 95% CI, 1.8-21.0). Participants who continued wear after 6 months reported greater improvement in mobility with real than sham prisms at crossover end (P = .002); participants who discontinued wear reported no difference. Real peripheral prism glasses were more helpful for obstacle avoidance when walking than sham glasses, with no differences between the horizontal and oblique designs. Peripheral prism glasses provide a simple and inexpensive mobility rehabilitation intervention for hemianopia. clinicaltrials.gov Identifier: NCT00494676.

A Randomized, Double-Blind, Crossover Comparison of MK-0929 and Placebo in the Treatment of Adults with ADHD

ERIC Educational Resources Information Center

Rivkin, Anna; Alexander, Robert C.; Knighton, Jennifer; Hutson, Pete H.; Wang, Xiaojing J.; Snavely, Duane B.; Rosah, Thomas; Watt, Alan P.; Reimherr, Fred W.; Adler, Lenard A.

2012-01-01

Objective: Preclinical models, receptor localization, and genetic linkage data support the role of D4 receptors in the etiology of ADHD. This proof-of-concept study was designed to evaluate MK-0929, a selective D4 receptor antagonist as treatment for adult ADHD. Method: A randomized, double-blind, placebo-controlled, crossover study was conducted…

Challenging Fiction: Exploring Meaning-Making Processes in the Crossover between Social Media and Drama in Education

ERIC Educational Resources Information Center

Knudsen, Kristian Nødtvedt

2018-01-01

The aim of this study was to explore how meaning-making activity can be expressed and shaped in the crossover between drama in education and social media. This study concerns the use of empirical material from an educational drama project called #iLive, which was designed and implemented, on four different occasions with a total of 89 students…

Web-Based Study of Risk Factors for Pain Exacerbation in Osteoarthritis of the Knee (SPARK-Web): Design and Rationale

PubMed Central

Metcalf, Ben; Zhang, Yuqing; Bennell, Kim; March, Lyn; Hunter, David J

2015-01-01

Background Knee osteoarthritis (OA) is the most frequent cause of limited mobility and diminished quality of life. Pain is the main symptom that drives individuals with knee OA to seek medical care and a recognized antecedent to disability and eventually joint replacement. Many persons with symptomatic knee OA experience recurrent pain exacerbations. Knowledge and clarification of risk factors for pain exacerbation may allow those affected to minimize reoccurrence of these episodes. Objective The aim of this study is to use a Web-based case-crossover design to identify risk factors for knee pain exacerbations in persons with symptomatic knee OA. Methods Web-based case-crossover design is used to study persons with symptomatic knee OA. Participants with knee pain and radiographic knee OA will be recruited and followed for 90 days. Participants will complete an online questionnaire at the baseline and every 10 days thereafter (totaling up to 10 control-period questionnaires); participants will also be asked to report online when they experience an episode of increased knee pain. Pain exacerbation will be defined as an increase in knee pain severity of two points from baseline on a numeric rating scale (NRS 0-10). Physical activity, footwear, knee injury, medication use, climate, psychological factors, and their possible interactions will be assessed as potential triggers for pain exacerbation using conditional logistic regression models. Results This project has been funded by the National Health and Medical Research Council (NHMRC). The enrollment for the study has started. So far, 343 participants have been enrolled. The study is expected to be finished in October 2015. Conclusions This study will identify risk factors for pain exacerbations in knee OA. The identification and possible modification/elimination of such risk factors will help to prevent the reoccurrence of pain exacerbation episodes and therefore improve knee OA management. PMID:26156210

Distracted Driving and Risk of Crash or Near-crash Involvement among Older Drivers using Naturalistic Driving Data with a Case-crossover Study Design.

PubMed

Huisingh, Carrie; Owsley, Cynthia; Levitan, Emily B; Irvin, Marguerite R; MacLennan, Paul; McGwin, Gerald

2018-05-17

The purpose of this study was to examine the association between secondary task involvement and risk of crash and near-crash involvement among older drivers using naturalistic driving data. Data from drivers aged ≥70 years in the Strategic Highway Research Program (SHRP2) Naturalistic Driving Study database was utilized. The personal vehicle of study participants was equipped with four video cameras enabling recording of the driver and the road environment. Secondary task involvement during a crash or near-crash event was compared to periods of non-crash involvement in a case-crossover study design. Conditional logistic regression was used to generate odds ratios (OR) and 95% confidence intervals (CI). Overall, engaging in any secondary task was not associated with crash (OR=0.94, 95% CI 0.68-1.29) or near-crash (OR=1.08, 95% CI 0.79-1.50) risk. The risk of a major crash event with cell phone use was 3.79 times higher than the risk with no cell phone use (95% CI 1.00-14.37). Other glances into the interior of the vehicle were associated with an increased risk of near-crash involvement (OR=2.55, 95% CI 1.24-5.26). Other distractions external to the vehicle were associated with a decreased risk of crash involvement (OR=0.53, 95% CI 0.30-0.94). Interacting with a passenger and talking/singing were not associated with crash or near-crash risk. Older drivers should avoid any cell phone use and minimize non-driving related eye glances towards the interior of the vehicle while driving. Certain types of events external to the vehicle are associated with a reduced crash risk among older drivers.

Transient physical and psychosocial activities increase the risk of nonpersistent and persistent low back pain: a case-crossover study with 12 months follow-up.

PubMed

Machado, Gustavo C; Ferreira, Paulo H; Maher, Chris G; Latimer, Jane; Steffens, Daniel; Koes, Bart W; Li, Qiang; Ferreira, Manuela L

2016-12-01

A previous study has shown that transient physical and psychosocial activities increased the risk of developing low back pain. However, the link between these factors in triggering nonpersistent or persistent episodes remains unclear. We aimed to investigate the association of transient exposures to physical and psychosocial activities with the development of nonpersistent or persistent low back pain. This was a case-crossover study with 12 months follow-up. We included 999 consecutive participants seeking care for a sudden onset of low back pain. Development of low back pain was the outcome measure. At baseline, participants reported transient exposures to 12 predefined activities over the 4 days preceding pain onset. After 12 months, participants were asked whether they had recovered and the date of recovery. Exposures in the 2-hour period preceding pain onset (case window) were compared with the 2-hour period, 24 hours before pain onset (control window) in a case-crossover design for all participants. Conditional logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CI), and interaction analyses were used to compare estimates of nonpersistent (i.e., <6 weeks duration) and persistent cases. This study received funding from Australia's National Health and Medical Research Council (APP1003608). There were 832 participants (83%) who completed the 12 months follow-up successfully. Of these, 430 participants had nonpersistent low back pain (<6 weeks duration), whereas 352 reported persistent symptoms (≥6 weeks duration). Exposure to several transient activities, such as manual tasks involving heavy loads, awkward postures, live people or animals, moderate or vigorous physical activity, and being fatigued or tired during a task or activity, significantly increased the risk of both nonpersistent and persistent low back pain, with ORs ranging from 2.9 to 11.7. Overall, the risk of developing a persistent or a nonpersistent episode of low back pain associated with the included physical factors did not differ significantly. Our results revealed that previously identified triggers contribute equally to the development of both nonpersistent and persistent low back pain. Future prevention strategies should focus on controlling exposure to these triggers as they have the potential to decrease the burden associated with both acute and chronic low back pain. Copyright © 2016 Elsevier Inc. All rights reserved.

Emotional stress as a trigger of falls leading to hip or pelvic fracture. Results from the ToFa study – a case-crossover study among elderly people in Stockholm, Sweden

PubMed Central

Möller, Jette; Hallqvist, Johan; Laflamme, Lucie; Mattsson, Fredrik; Ponzer, Sari; Sadigh, Siv; Engström, Karin

2009-01-01

Background Sudden emotions may interfere with mechanisms for keeping balance among the elderly. The aim of this study is to analyse if emotional stress and specifically feelings of anger, sadness, worries, anxiety or stress, can trigger falls leading to hip or pelvic fracture among autonomous older people. Methods The study applied the case-crossover design and was based on data gathered by face to face interviews carried out in Stockholm between November 2004 and January 2006 at the emergency wards of two hospitals. Cases (n = 137) were defined as persons aged 65 and older admitted for at least one night due to a fall-related hip or pelvic fracture (ICD10: S72 or S32) and meeting a series of selection criteria. Results are presented as relative risks with 95% confidence intervals. Results There was an increased risk for fall and subsequent hip or pelvic fracture for up to one hour after emotional stress. For anger there was an increased relative risk of 12.2 (95% CI 2.7–54.7), for sadness of 5.7 (95% CI 1.1–28.7), and for stress 20.6 (95% CI 4.5–93.5) compared to periods with no such feelings. Conclusion Emotional stress seems to have the potential to trigger falls and subsequent hip or pelvic fracture among autonomous older people. Further studies are needed to clarify how robust the findings are – as the number of exposed cases is small – and the mechanisms behind them – presumably balance and vision impairment in stress situation. PMID:19203356

Double-Blind, Placebo-Controlled, Crossover Study of the Efficacy and Safety of Lisdexamfetamine Dimesylate in College Students with ADHD

ERIC Educational Resources Information Center

DuPaul, George J.; Weyandt, Lisa L.; Rossi, Joseph S.; Vilardo, Brigid A.; O'Dell, Sean M.; Carson, Kristen M.; Verdi, Genevieve; Swentosky, Anthony

2012-01-01

Objective: To evaluate stimulant medication on symptoms and functioning for college students with ADHD using double-blind, placebo-controlled, crossover design. Method: Participants included 24 college students with ADHD and 26 college students without psychopathology. Lisdexamfetamine dimesylate (LDX) was examined for ADHD participants over five…

Application of a Time-Stratified Case-Crossover Design to Explore the Effects of Air Pollution and Season on Childhood Asthma Hospitalization in Cities of Differing Urban Patterns: Big Data Analytics of Government Open Data.

PubMed

Kuo, Ching-Yen; Pan, Ren-Hao; Chan, Chin-Kan; Wu, Chiung-Yi; Phan, Dinh-Van; Chan, Chien-Lung

2018-03-31

Few studies have assessed the lagged effects of levels of different urban city air pollutants and seasons on asthma hospitalization in children. This study used big data analysis to explore the effects of daily changes in air pollution and season on childhood asthma hospitalization from 2001 to 2010 in Taipei and Kaohsiung City, Taiwan. A time-stratified case-crossover study and conditional logistic regression analysis were employed to identify associations between the risk of hospitalization due to asthma in children and the levels of air pollutants (PM 2.5 , PM 10 , O₃, SO₂, and NO₂) in the days preceding hospitalization. During the study period, 2900 children in Taipei and 1337 in Kaohsiung aged ≤15 years were hospitalized due to asthma for the first time. The results indicated that the levels of air pollutants were significantly associated with the risk of asthma hospitalization in children, and seasonal effects were observed. High levels of air pollution in Kaohsiung had greater effects than in Taipei after adjusting for seasonal variation. The most important factor was O₃ in spring in Taipei. In children aged 0-6 years, asthma was associated with O₃ in Taipei and SO₂ in Kaohsiung, after controlling for the daily mean temperature and relative humidity.

Atmospheric Pressure and Abdominal Aortic Aneurysm Rupture: Results From a Time Series Analysis and Case-Crossover Study.

PubMed

Penning de Vries, Bas B L; Kolkert, Joé L P; Meerwaldt, Robbert; Groenwold, Rolf H H

2017-10-01

Associations between atmospheric pressure and abdominal aortic aneurysm (AAA) rupture risk have been reported, but empirical evidence is inconclusive and largely derived from studies that did not account for possible nonlinearity, seasonality, and confounding by temperature. Associations between atmospheric pressure and AAA rupture risk were investigated using local meteorological data and a case series of 358 patients admitted to hospital for ruptured AAA during the study period, January 2002 to December 2012. Two analyses were performed-a time series analysis and a case-crossover study. Results from the 2 analyses were similar; neither the time series analysis nor the case-crossover study showed a significant association between atmospheric pressure ( P = .627 and P = .625, respectively, for mean daily atmospheric pressure) or atmospheric pressure variation ( P = .464 and P = .816, respectively, for 24-hour change in mean daily atmospheric pressure) and AAA rupture risk. This study failed to support claims that atmospheric pressure causally affects AAA rupture risk. In interpreting our results, one should be aware that the range of atmospheric pressure observed in this study is not representative of the atmospheric pressure to which patients with AAA may be exposed, for example, during air travel or travel to high altitudes in the mountains. Making firm claims regarding these conditions in relation to AAA rupture risk is difficult at best. Furthermore, despite the fact that we used one of the largest case series to date to investigate the effect of atmospheric pressure on AAA rupture risk, it is possible that this study is simply too small to demonstrate a causal link.

Test equality in binary data for a 4 × 4 crossover trial under a Latin-square design.

PubMed

Lui, Kung-Jong; Chang, Kuang-Chao

2016-10-15

When there are four or more treatments under comparison, the use of a crossover design with a complete set of treatment-receipt sequences in binary data is of limited use because of too many treatment-receipt sequences. Thus, we may consider use of a 4 × 4 Latin square to reduce the number of treatment-receipt sequences when comparing three experimental treatments with a control treatment. Under a distribution-free random effects logistic regression model, we develop simple procedures for testing non-equality between any of the three experimental treatments and the control treatment in a crossover trial with dichotomous responses. We further derive interval estimators in closed forms for the relative effect between treatments. To evaluate the performance of these test procedures and interval estimators, we employ Monte Carlo simulation. We use the data taken from a crossover trial using a 4 × 4 Latin-square design for studying four-treatments to illustrate the use of test procedures and interval estimators developed here. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Sample size determination for equivalence assessment with multiple endpoints.

PubMed

Sun, Anna; Dong, Xiaoyu; Tsong, Yi

2014-01-01

Equivalence assessment between a reference and test treatment is often conducted by two one-sided tests (TOST). The corresponding power function and sample size determination can be derived from a joint distribution of the sample mean and sample variance. When an equivalence trial is designed with multiple endpoints, it often involves several sets of two one-sided tests. A naive approach for sample size determination in this case would select the largest sample size required for each endpoint. However, such a method ignores the correlation among endpoints. With the objective to reject all endpoints and when the endpoints are uncorrelated, the power function is the production of all power functions for individual endpoints. With correlated endpoints, the sample size and power should be adjusted for such a correlation. In this article, we propose the exact power function for the equivalence test with multiple endpoints adjusted for correlation under both crossover and parallel designs. We further discuss the differences in sample size for the naive method without and with correlation adjusted methods and illustrate with an in vivo bioequivalence crossover study with area under the curve (AUC) and maximum concentration (Cmax) as the two endpoints.

Study protocol and rationale for a randomized double-blinded crossover trial of phentermine-topiramate ER versus placebo to treat binge eating disorder and bulimia nervosa.

PubMed

Dalai, Shebani Sethi; Adler, Sarah; Najarian, Thomas; Safer, Debra Lynn

2018-01-01

Bulimia nervosa (BN) and binge eating disorder (BED) are associated with severe psychological and medical consequences. Current therapies are limited, leaving up to 50% of patients symptomatic despite treatment, underscoring the need for additional treatment options. Qsymia, an FDA-approved medication for obesity, combines phentermine and topiramate ER. Topiramate has demonstrated efficacy for both BED and BN, but limited tolerability. Phentermine is FDA-approved for weight loss. A rationale for combined phentermine/topiramate for BED and BN is improved tolerability and efficacy. While a prior case series exploring Qsymia for BED showed promise, randomized studies are needed to evaluate Qsymia's safety and efficacy when re-purposed in eating disorders. We present a study protocol for a Phase I/IIa single-center, prospective, double-blinded, randomized, crossover trial examining safety and preliminary efficacy of Qsymia for BED and BN. Adults with BED (n=15) or BN (n=15) are randomized 1:1 to receive 12weeks Qsymia (phentermine/topiramate ER, 3.75mg/23mg-15mg/92mg) or placebo, followed by 2-weeks washout and 12-weeks crossover, where those on Qsymia receive placebo and vice versa. Subsequently participants receive 8weeks follow-up off study medications. The primary outcome is the number of binge days/week measured by EDE. Secondary outcomes include average number of binge episodes, percentage abstinence from binge eating, and changes in weight/vitals, eating psychopathology, and mood. To our knowledge this is the first randomized, double-blind protocol investigating the safety and efficacy of phentermine/topiramate in BED and BN. We highlight the background and rationale for this study, including the advantages of a crossover design. Clinicaltrials.gov identifier NCT02553824 registered on 9/17/2015. https://clinicaltrials.gov/ct2/show/NCT02553824. Copyright © 2017 Elsevier Inc. All rights reserved.

Cross-over studies underestimate energy compensation: The example of sucrose-versus sucralose-containing drinks.

PubMed

Gadah, Nouf S; Brunstrom, Jeffrey M; Rogers, Peter J

2016-12-01

The vast majority of preload-test-meal studies that have investigated the effects on energy intake of disguised nutrient or other food/drink ingredient manipulations have used a cross-over design. We argue that this design may underestimate the effect of the manipulation due to carry-over effects. To test this we conducted comparable cross-over (n = 69) and parallel-groups (n = 48) studies testing the effects of sucrose versus low-calorie sweetener (sucralose) in a drink preload on test-meal energy intake. The parallel-groups study included a baseline day in which only the test meal was consumed. Energy intake in that meal was used to control for individual differences in energy intake in the analysis of the effects of sucrose versus sucralose on energy intake on the test day. Consistent with our prediction, the effect of consuming sucrose on subsequent energy intake was greater when measured in the parallel-groups study than in the cross-over study (respectively 64% versus 36% compensation for the 162 kcal difference in energy content of the sucrose and sucralose drinks). We also included a water comparison group in the parallel-groups study (n = 24) and found that test-meal energy intake did not differ significantly between the water and sucralose conditions. Together, these results confirm that consumption of sucrose in a drink reduces subsequent energy intake, but by less than the energy content of the drink, whilst drink sweetness does not increase food energy intake. Crucially, though, the studies demonstrate that study design affects estimated energy compensation. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Performance factors of mobile rich media job aids for community health workers

PubMed Central

Florez-Arango, Jose F; Dunn, Kim; Zhang, Jiajie

2011-01-01

Objective To study and analyze the possible benefits on performance of community health workers using point-of-care clinical guidelines implemented as interactive rich media job aids on small-format mobile platforms. Design A crossover study with one intervention (rich media job aids) and one control (traditional job aids), two periods, with 50 community health workers, each subject solving a total 15 standardized cases per period per period (30 cases in total per subject). Measurements Error rate per case and task, protocol compliance. Results A total of 1394 cases were evaluated. Intervention reduces errors by an average of 33.15% (p=0.001) and increases protocol compliance 30.18% (p<0.001). Limitations Medical cases were presented on human patient simulators in a laboratory setting, not on real patients. Conclusion These results indicate encouraging prospects for mHealth technologies in general, and the use of rich media clinical guidelines on cell phones in particular, for the improvement of community health worker performance in developing countries. PMID:21292702

Sanitary Sewer Overflows and Association with Gastrointestinal Illness: A case crossover analysis of Massachusetts Data, 2006-2007

EPA Science Inventory

Sanitary sewer overflows (SSOs) occur when untreated sewage is discharged into water sources potentially causing contamination. SSOs are primarily caused by heavy rainfall, which is expected to become heavier and more episodic due to climate change. We conducted a case-crossover ...

Route Infrastructure and the Risk of Injuries to Bicyclists: A Case-Crossover Study

PubMed Central

Harris, M. Anne; Reynolds, Conor C. O.; Winters, Meghan; Babul, Shelina; Chipman, Mary; Cusimano, Michael D.; Brubacher, Jeff R.; Hunte, Garth; Friedman, Steven M.; Monro, Melody; Shen, Hui; Vernich, Lee; Cripton, Peter A.

2012-01-01

Objectives. We compared cycling injury risks of 14 route types and other route infrastructure features. Methods. We recruited 690 city residents injured while cycling in Toronto or Vancouver, Canada. A case-crossover design compared route infrastructure at each injury site to that of a randomly selected control site from the same trip. Results. Of 14 route types, cycle tracks had the lowest risk (adjusted odds ratio [OR] = 0.11; 95% confidence interval [CI] = 0.02, 0.54), about one ninth the risk of the reference: major streets with parked cars and no bike infrastructure. Risks on major streets were lower without parked cars (adjusted OR = 0.63; 95% CI = 0.41, 0.96) and with bike lanes (adjusted OR = 0.54; 95% CI = 0.29, 1.01). Local streets also had lower risks (adjusted OR = 0.51; 95% CI = 0.31, 0.84). Other infrastructure characteristics were associated with increased risks: streetcar or train tracks (adjusted OR = 3.0; 95% CI = 1.8, 5.1), downhill grades (adjusted OR = 2.3; 95% CI = 1.7, 3.1), and construction (adjusted OR = 1.9; 95% CI = 1.3, 2.9). Conclusions. The lower risks on quiet streets and with bike-specific infrastructure along busy streets support the route-design approach used in many northern European countries. Transportation infrastructure with lower bicycling injury risks merits public health support to reduce injuries and promote cycling. PMID:23078480

Orbital Transfer Vehicle Engine Technology High Velocity Ratio Diffusing Crossover

NASA Technical Reports Server (NTRS)

Lariviere, Brian W.

1992-01-01

High speed, high efficiency head rise multistage pumps require continuous passage diffusing crossovers to effectively convey the pumped fluid from the exit of one impeller to the inlet of the next impeller. On Rocketdyne's Orbital Transfer Vehicle (OTV), the MK49-F, a three stage high pressure liquid hydrogen turbopump, utilizes a 6.23 velocity ratio diffusing crossover. This velocity ratio approaches the diffusion limits for stable and efficient flow over the operating conditions required by the OTV system. The design of the high velocity ratio diffusing crossover was based on advanced analytical techniques anchored by previous tests of stationary two-dimensional diffusers with steady flow. To secure the design and the analytical techniques, tests were required with the unsteady whirling characteristics produced by an impeller. A tester was designed and fabricated using a 2.85 times scale model of the MK49-F turbopumps first stage, including the inducer, impeller, and the diffusing crossover. Water and air tests were completed to evaluate the large scale turbulence, non-uniform velocity, and non-steady velocity on the pump and crossover head and efficiency. Suction performance tests from 80 percent to 124 percent of design flow were completed in water to assess these pump characteristics. Pump and diffuser performance from the water and air tests were compared with the actual MK49-F test data in liquid hydrogen.

Single Center Retrospective Analysis of Conventional and Radial TIG Catheters for Transradial Diagnostic Coronary Angiography.

PubMed

Vorpahl, Marc; Koehler, Till; Foerst, Jason; Panagiotopoulos, Spyridon; Schleiting, Heinrich; Koss, Klaus; Ziegler, Gunda; Brinkmann, Hilmar; Seyfarth, Melchior; Tiroch, Klaus

2015-01-01

Current guidelines favor the radial approach for coronary angiography. Therefore, specialty radial diagnostic catheters were designed to engage both coronary arteries with a single device. However, it is unclear if single catheters are superior to conventional catheters. A retrospective analysis was performed of consecutive right radial coronary angiographies to determine catheter use, fluoroscopy time, radiation dosage, and consumption of contrast. Procedures were performed with a single TIG catheter or conventional catheters (CONV). Procedures with coronary artery bypass grafts or ventricular angiographies were excluded. 273 transradial procedures were performed successfully. 95 procedures were performed with CONV and 178 procedures with a TIG. Crossover to additional catheters was higher in TIG (15.2%) compared to CONV (5.3%, p = 0.02). Fluoroscopy time was comparable between CONV and TIG, without crossover (2.2 ± 1.2 min versus 2.3 ± 1.2 min; n.s.), however, greater in the case of crossover for CONV (5.8 ± 0.7) and TIG (7.6 ± 3.0; p = 0.0001). Radiation dosage was similar in CONV and the TIG, without crossover (1419 ± 1075, cGy∗cm(2) versus 1690 ± 1138; n.s.), however, greater for CONV (2374 ± 620) and TIG (3733 ± 2281, p = 0.05) with crossover. Overall, the amount of contrast was greater in TIG (56 ± 13 mL) versus CONV (48 ± 3 mL; p = 0.0003). CONV femoral catheters may be the primary choice for radial approach.

Crossover ensembles of random matrices and skew-orthogonal polynomials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, Santosh, E-mail: skumar.physics@gmail.com; Pandey, Akhilesh, E-mail: ap0700@mail.jnu.ac.in

2011-08-15

Highlights: > We study crossover ensembles of Jacobi family of random matrices. > We consider correlations for orthogonal-unitary and symplectic-unitary crossovers. > We use the method of skew-orthogonal polynomials and quaternion determinants. > We prove universality of spectral correlations in crossover ensembles. > We discuss applications to quantum conductance and communication theory problems. - Abstract: In a recent paper (S. Kumar, A. Pandey, Phys. Rev. E, 79, 2009, p. 026211) we considered Jacobi family (including Laguerre and Gaussian cases) of random matrix ensembles and reported exact solutions of crossover problems involving time-reversal symmetry breaking. In the present paper we givemore » details of the work. We start with Dyson's Brownian motion description of random matrix ensembles and obtain universal hierarchic relations among the unfolded correlation functions. For arbitrary dimensions we derive the joint probability density (jpd) of eigenvalues for all transitions leading to unitary ensembles as equilibrium ensembles. We focus on the orthogonal-unitary and symplectic-unitary crossovers and give generic expressions for jpd of eigenvalues, two-point kernels and n-level correlation functions. This involves generalization of the theory of skew-orthogonal polynomials to crossover ensembles. We also consider crossovers in the circular ensembles to show the generality of our method. In the large dimensionality limit, correlations in spectra with arbitrary initial density are shown to be universal when expressed in terms of a rescaled symmetry breaking parameter. Applications of our crossover results to communication theory and quantum conductance problems are also briefly discussed.« less

The number of flares patients experience impacts on damage accrual in systemic lupus erythematosus: data from a multiethnic Latin American cohort.

PubMed

Ugarte-Gil, Manuel F; Acevedo-Vásquez, Eduardo; Alarcón, Graciela S; Pastor-Asurza, Cesar A; Alfaro-Lozano, José L; Cucho-Venegas, Jorge M; Segami, Maria I; Wojdyla, Daniel; Soriano, Enrique R; Drenkard, Cristina; Brenol, João Carlos; de Oliveira e Silva Montandon, Ana Carolina; Costallat, Lilian T Lavras; Massardo, Loreto; Molina-Restrepo, José F; Guibert-Toledano, Marlene; Silveira, Luis H; Amigo, Mary Carmen; Barile-Fabris, Leonor A; Chacón-Díaz, Rosa; Esteva-Spinetti, Maria H; Pons-Estel, Guillermo J; McGwin, Gerald; Pons-Estel, Bernardo A

2015-06-01

To determine the association between the number of flares systemic lupus erythematosus (SLE) patients experience and damage accrual, independently of other known risk factors. SLE patients (34 centres, nine Latin American countries) with a recent diagnosis (≤2 years) and ≥3 evaluations were studied. Disease activity was ascertained with the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) and damage with the SLICC/ACR Damage Index (SDI). Flare was defined as an increase ≥4 points in the SLEDAI between two study visits. An ambidirectional case- crossover design was used to determine the association between the number of flares and damage accrual. 901 patients were eligible for the study; 500 of them (55.5%) experienced at least one flare, being the mean number of flares 0.9 (SD: 1.0). 574 intervals from 251 patients were included in the case-crossover design since they have case and control intervals, whereas, the remaining patients did not. Their mean age at diagnosis was 27.9 years (SD: 11.1), 213 (84.9%) were women. The mean baseline SDI and SLEDAI were 1.3 (1.3) and 13.6 (8.1), respectively. Other features were comparable to those of the entire sample. After adjusting for possible confounding variables, the number of flares, regardless of their severity, was associated with damage accrual (SDI) OR 2.05, 95% CI 1.43 to 2.94, p<0.001 (OR 2.62, 95% CI 1.31 to 5.24, p=0.006 for severe and OR 1.91, 95% CI 1.28 to 2.83, p=0.001 for mild-moderate). The number of flares patients experience, regardless of their severity, increases the risk of damage accrual, independently of other known risk factors. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

24 CFR 3285.604 - Drainage system.

Code of Federal Regulations, 2010 CFR

2010-04-01

... require drainage system crossover connections to join all sections of the home. The crossover design... all sections of the home and designed to be located underneath the home, they must be installed and... DEVELOPMENT MODEL MANUFACTURED HOME INSTALLATION STANDARDS Ductwork and Plumbing and Fuel Supply Systems...

Prescription medicine use by pedestrians and the risk of injurious road traffic crashes: A case-crossover study.

PubMed

Née, Mélanie; Avalos, Marta; Luxcey, Audrey; Contrand, Benjamin; Salmi, Louis-Rachid; Fourrier-Réglat, Annie; Gadegbeku, Blandine; Lagarde, Emmanuel; Orriols, Ludivine

2017-07-01

While some medicinal drugs have been found to affect driving ability, no study has investigated whether a relationship exists between these medicines and crashes involving pedestrians. The aim of this study was to explore the association between the use of medicinal drugs and the risk of being involved in a road traffic crash as a pedestrian. Data from 3 French nationwide databases were matched. We used the case-crossover design to control for time-invariant factors by using each case as its own control. To perform multivariable analysis and limit false-positive results, we implemented a bootstrap version of Lasso. To avoid the effect of unmeasured time-varying factors, we varied the length of the washout period from 30 to 119 days before the crash. The matching procedure led to the inclusion of 16,458 pedestrians involved in an injurious road traffic crash from 1 July 2005 to 31 December 2011. We found 48 medicine classes with a positive association with the risk of crash, with median odds ratios ranging from 1.12 to 2.98. Among these, benzodiazepines and benzodiazepine-related drugs, antihistamines, and anti-inflammatory and antirheumatic drugs were among the 10 medicines most consumed by the 16,458 pedestrians. Study limitations included slight overrepresentation of pedestrians injured in more severe crashes, lack of information about self-medication and the use of over-the-counter drugs, and lack of data on amount of walking. Therapeutic classes already identified as impacting the ability to drive, such as benzodiazepines and antihistamines, are also associated with an increased risk of pedestrians being involved in a road traffic crash. This study on pedestrians highlights the necessity of improving awareness of the effect of these medicines on this category of road user.

Application of a Time-Stratified Case-Crossover Design to Explore the Effects of Air Pollution and Season on Childhood Asthma Hospitalization in Cities of Differing Urban Patterns: Big Data Analytics of Government Open Data

PubMed Central

Chan, Chin-Kan; Wu, Chiung-Yi

2018-01-01

Few studies have assessed the lagged effects of levels of different urban city air pollutants and seasons on asthma hospitalization in children. This study used big data analysis to explore the effects of daily changes in air pollution and season on childhood asthma hospitalization from 2001 to 2010 in Taipei and Kaohsiung City, Taiwan. A time-stratified case-crossover study and conditional logistic regression analysis were employed to identify associations between the risk of hospitalization due to asthma in children and the levels of air pollutants (PM2.5, PM10, O3, SO2, and NO2) in the days preceding hospitalization. During the study period, 2900 children in Taipei and 1337 in Kaohsiung aged ≤15 years were hospitalized due to asthma for the first time. The results indicated that the levels of air pollutants were significantly associated with the risk of asthma hospitalization in children, and seasonal effects were observed. High levels of air pollution in Kaohsiung had greater effects than in Taipei after adjusting for seasonal variation. The most important factor was O3 in spring in Taipei. In children aged 0–6 years, asthma was associated with O3 in Taipei and SO2 in Kaohsiung, after controlling for the daily mean temperature and relative humidity. PMID:29614737

Six different roles for crossover inhibition in the retina: correcting the nonlinearities of synaptic transmission.

PubMed

Werblin, Frank S

2010-03-01

Early retinal studies categorized ganglion cell behavior as either linear or nonlinear and rectifying as represented by the familiar X- and Y-type ganglion cells in cat. Nonlinear behavior is in large part a consequence of the rectifying nonlinearities inherent in synaptic transmission. These nonlinear signals underlie many special functions in retinal processing, including motion detection, motion in motion, and local edge detection. But linear behavior is also required for some visual processing tasks. For these tasks, the inherently nonlinear signals are "linearized" by "crossover inhibition." Linearization utilizes a circuitry whereby nonlinear ON inhibition adds with nonlinear OFF excitation or ON excitation adds with OFF inhibition to generate a more linear postsynaptic voltage response. Crossover inhibition has now been measured in most bipolar, amacrine, and ganglion cells. Functionally crossover inhibition enhances edge detection, allows ganglion cells to recognize luminance-neutral patterns with their receptive fields, permits ganglion cells to distinguish contrast from luminance, and maintains a more constant conductance during the light response. In some cases, crossover extends the operating range of cone-driven OFF ganglion cells into the scotopic levels. Crossover inhibition is also found in neurons of the lateral geniculate nucleus and V1.

Within-Subject Mediation Analysis in AB/BA Crossover Designs.

PubMed

Josephy, Haeike; Vansteelandt, Stijn; Vanderhasselt, Marie-Anne; Loeys, Tom

2015-05-01

Crossover trials are widely used to assess the effect of a reversible exposure on an outcome of interest. To gain further insight into the underlying mechanisms of this effect, researchers may be interested in exploring whether or not it runs through a specific intermediate variable: the mediator. Mediation analysis in crossover designs has received scant attention so far and is mostly confined to the traditional Baron and Kenny approach. We aim to tackle mediation analysis within the counterfactual framework and elucidate the assumptions under which the direct and indirect effects can be identified in AB/BA crossover studies. Notably, we show that both effects are identifiable in certain statistical models, even in the presence of unmeasured time-independent (or upper-level) confounding of the mediator-outcome relation. Employing the mediation formula, we derive expressions for the direct and indirect effects in within-subject designs for continuous outcomes that lend themselves to linear modelling, under a large variety of settings. We discuss an estimation approach based on regressing differences in outcomes on differences in mediators and show how to allow for period effects as well as different types of moderation. The performance of this approach is compared to other existing methods through simulations and is illustrated with data from a neurobehavioural study. Lastly, we demonstrate how a sensitivity analysis can be performed that is able to assess the robustness of both the direct and indirect effect against violation of the "no unmeasured lower-level mediator-outcome confounding" assumption.

Computer-Enriched Instruction (CEI) Is Better for Preview Material Instead of Review Material: An Example of a Biostatistics Chapter, the Central Limit Theorem

ERIC Educational Resources Information Center

See, Lai-Chu; Huang, Yu-Hsun; Chang, Yi-Hu; Chiu, Yeo-Ju; Chen, Yi-Fen; Napper, Vicki S.

2010-01-01

This study examines the timing using computer-enriched instruction (CEI), before or after a traditional lecture to determine cross-over effect, period effect, and learning effect arising from sequencing of instruction. A 2 x 2 cross-over design was used with CEI to teach central limit theorem (CLT). Two sequences of graduate students in nursing…

Interference-mediated synaptonemal complex formation with embedded crossover designation

PubMed Central

Zhang, Liangran; Espagne, Eric; de Muyt, Arnaud; Zickler, Denise; Kleckner, Nancy E.

2014-01-01

Biological systems exhibit complex patterns at length scales ranging from the molecular to the organismic. Along chromosomes, events often occur stochastically at different positions in different nuclei but nonetheless tend to be relatively evenly spaced. Examples include replication origin firings, formation of chromatin loops along chromosome axes and, during meiosis, localization of crossover recombination sites (“crossover interference”). We present evidence in the fungus Sordaria macrospora that crossover interference is part of a broader pattern that includes synaptonemal complex (SC) nucleation. This pattern comprises relatively evenly spaced SC nucleation sites, among which a subset are crossover sites that show a classical interference distribution. This pattern ensures that SC forms regularly along the entire length of the chromosome as required for the maintenance of homolog pairing while concomitantly having crossover interactions locally embedded within the SC structure as required for both DNA recombination and structural events of chiasma formation. This pattern can be explained by a threshold-based designation and spreading interference process. This model can be generalized to give diverse types of related and/or partially overlapping patterns, in two or more dimensions, for any type of object. PMID:25380597

Statistical power analysis of cardiovascular safety pharmacology studies in conscious rats.

PubMed

Bhatt, Siddhartha; Li, Dingzhou; Flynn, Declan; Wisialowski, Todd; Hemkens, Michelle; Steidl-Nichols, Jill

2016-01-01

Cardiovascular (CV) toxicity and related attrition are a major challenge for novel therapeutic entities and identifying CV liability early is critical for effective derisking. CV safety pharmacology studies in rats are a valuable tool for early investigation of CV risk. Thorough understanding of data analysis techniques and statistical power of these studies is currently lacking and is imperative for enabling sound decision-making. Data from 24 crossover and 12 parallel design CV telemetry rat studies were used for statistical power calculations. Average values of telemetry parameters (heart rate, blood pressure, body temperature, and activity) were logged every 60s (from 1h predose to 24h post-dose) and reduced to 15min mean values. These data were subsequently binned into super intervals for statistical analysis. A repeated measure analysis of variance was used for statistical analysis of crossover studies and a repeated measure analysis of covariance was used for parallel studies. Statistical power analysis was performed to generate power curves and establish relationships between detectable CV (blood pressure and heart rate) changes and statistical power. Additionally, data from a crossover CV study with phentolamine at 4, 20 and 100mg/kg are reported as a representative example of data analysis methods. Phentolamine produced a CV profile characteristic of alpha adrenergic receptor antagonism, evidenced by a dose-dependent decrease in blood pressure and reflex tachycardia. Detectable blood pressure changes at 80% statistical power for crossover studies (n=8) were 4-5mmHg. For parallel studies (n=8), detectable changes at 80% power were 6-7mmHg. Detectable heart rate changes for both study designs were 20-22bpm. Based on our results, the conscious rat CV model is a sensitive tool to detect and mitigate CV risk in early safety studies. Furthermore, these results will enable informed selection of appropriate models and study design for early stage CV studies. Copyright © 2016 Elsevier Inc. All rights reserved.

Influence diagnostics for count data under AB-BA crossover trials.

PubMed

Hao, Chengcheng; von Rosen, Dietrich; von Rosen, Tatjana

2017-12-01

This paper aims to develop diagnostic measures to assess the influence of data perturbations on estimates in AB-BA crossover studies with a Poisson distributed response. Generalised mixed linear models with normally distributed random effects are utilised. We show that in this special case, the model can be decomposed into two independent sub-models which allow to derive closed-form expressions to evaluate the changes in the maximum likelihood estimates under several perturbation schemes. The performance of the new influence measures is illustrated by simulation studies and the analysis of a real dataset.

Triggers for Preeclampsia Onset: a Case-Crossover Study.

PubMed

Ford, Jane B; Schemann, Kathrin; Patterson, Jillian A; Morris, Jonathan; Herbert, Robert D; Roberts, Christine L

2016-11-01

Risk factors for preeclampsia are well established, whereas, the triggers associated with timing of preeclampsia onset are not. The aim of this study was to establish whether recent infection or other triggers were associated with timing of preeclampsia onset. We used a case-crossover design with preeclampsia cases serving as their own controls. Women with singleton pregnancies of ≥20 weeks gestation presenting at three hospitals were eligible for inclusion. Exposures to potential triggers were identified via guided questionnaire. Infective episodes included symptoms lasting >24 h. Preeclampsia was defined as hypertension (BP ≥140 mmHg and/or ≥90 mmHg) and proteinuria (protein/creatinine ratio ≥30 mg/mmol). Conditional logistic regression was used to compare the odds of exposure to potential triggers in the case windows (1-7 days preceding diagnosis of preeclampsia) and control windows (8-14 days prior to diagnosis); unadjusted odds ratios (ORs) are reported. Among 286 recruited women, 25 (8.7%) reported a new infection in the 7 days prior to preeclampsia onset and 21 (7.3%) in the 8-14 days prior. There was no significant association between onset of infection in the 7 days prior and preeclampsia diagnosis (OR 1.24, 95% CI 0.65, 2.34). Consumption of caffeine (OR 0.51, 95% CI 0.33, 0.77), spicy food (OR 0.49, 95% CI 0.30, 0.81), and alcohol (OR 0.26, 95% CI 0.10, 0.71) were strongly inversely associated with preeclampsia onset. Recent infection does not appear to trigger preeclampsia. Decreased consumption of caffeine, spicy food, and alcohol may be prodromal markers. Such behaviours may be early markers of imminent preeclampsia. © 2016 John Wiley & Sons Ltd.

A Case Study of Controlling Crossover in a Selection Hyper-heuristic Framework Using the Multidimensional Knapsack Problem.

PubMed

Drake, John H; Özcan, Ender; Burke, Edmund K

2016-01-01

Hyper-heuristics are high-level methodologies for solving complex problems that operate on a search space of heuristics. In a selection hyper-heuristic framework, a heuristic is chosen from an existing set of low-level heuristics and applied to the current solution to produce a new solution at each point in the search. The use of crossover low-level heuristics is possible in an increasing number of general-purpose hyper-heuristic tools such as HyFlex and Hyperion. However, little work has been undertaken to assess how best to utilise it. Since a single-point search hyper-heuristic operates on a single candidate solution, and two candidate solutions are required for crossover, a mechanism is required to control the choice of the other solution. The frameworks we propose maintain a list of potential solutions for use in crossover. We investigate the use of such lists at two conceptual levels. First, crossover is controlled at the hyper-heuristic level where no problem-specific information is required. Second, it is controlled at the problem domain level where problem-specific information is used to produce good-quality solutions to use in crossover. A number of selection hyper-heuristics are compared using these frameworks over three benchmark libraries with varying properties for an NP-hard optimisation problem: the multidimensional 0-1 knapsack problem. It is shown that allowing crossover to be managed at the domain level outperforms managing crossover at the hyper-heuristic level in this problem domain.

Single Center Retrospective Analysis of Conventional and Radial TIG Catheters for Transradial Diagnostic Coronary Angiography

PubMed Central

Vorpahl, Marc; Koehler, Till; Foerst, Jason; Panagiotopoulos, Spyridon; Schleiting, Heinrich; Koss, Klaus; Ziegler, Gunda; Brinkmann, Hilmar; Seyfarth, Melchior; Tiroch, Klaus

2015-01-01

Current guidelines favor the radial approach for coronary angiography. Therefore, specialty radial diagnostic catheters were designed to engage both coronary arteries with a single device. However, it is unclear if single catheters are superior to conventional catheters. A retrospective analysis was performed of consecutive right radial coronary angiographies to determine catheter use, fluoroscopy time, radiation dosage, and consumption of contrast. Procedures were performed with a single TIG catheter or conventional catheters (CONV). Procedures with coronary artery bypass grafts or ventricular angiographies were excluded. 273 transradial procedures were performed successfully. 95 procedures were performed with CONV and 178 procedures with a TIG. Crossover to additional catheters was higher in TIG (15.2%) compared to CONV (5.3%, p = 0.02). Fluoroscopy time was comparable between CONV and TIG, without crossover (2.2 ± 1.2 min versus 2.3 ± 1.2 min; n.s.), however, greater in the case of crossover for CONV (5.8 ± 0.7) and TIG (7.6 ± 3.0; p = 0.0001). Radiation dosage was similar in CONV and the TIG, without crossover (1419 ± 1075, cGy∗cm2 versus 1690 ± 1138; n.s.), however, greater for CONV (2374 ± 620) and TIG (3733 ± 2281, p = 0.05) with crossover. Overall, the amount of contrast was greater in TIG (56 ± 13 mL) versus CONV (48 ± 3 mL; p = 0.0003). CONV femoral catheters may be the primary choice for radial approach. PMID:26435876

Air pollution is associated with primary health care visits for asthma in Sweden: A case-crossover design with a distributed lag non-linear model.

PubMed

Taj, Tahir; Jakobsson, Kristina; Stroh, Emilie; Oudin, Anna

2016-05-01

Air pollution can increase the symptoms of asthma and has an acute effect on the number of emergency room visits and hospital admissions because of asthma, but little is known about the effect of air pollution on the number of primary health care (PHC) visits for asthma. To investigate the association between air pollution and the number of PHC visits for asthma in Scania, southern Sweden. Data on daily PHC visits for asthma were obtained from a regional healthcare database in Scania, which covers approximately half a million people. Air pollution data from 2005 to 2010 were obtained from six urban background stations. We used a case-crossover study design and a distributed lag non-linear model in the analysis. The air pollution levels were generally within the EU air quality guidelines. The mean number of daily PHC visits for asthma was 34. The number of PHC visits increased by 5% (95% confidence interval (CI): 3.91-6.25%) with every 10µg m(-3) increase in daily mean NO2 lag (0-15), suggesting that daily air pollution levels are associated with PHC visits for asthma. Even though the air quality in Scania between 2005 and 2010 was within EU's guidelines, the number of PHC visits for asthma increased with increasing levels of air pollution. This suggests that as well as increasing hospital and emergency room visits, air pollution increases the burden on PHC due to milder symptoms of asthma. Copyright © 2016 Elsevier Ltd. All rights reserved.

Prescription of Zolpidem and the Risk of Fatal Motor Vehicle Collisions: A Population-Based, Case-Crossover Study from South Korea.

PubMed

Yang, Bo Ram; Kim, Ye-Jee; Kim, Mi-Sook; Jung, Sun-Young; Choi, Nam-Kyong; Hwang, Byungkwan; Park, Byung-Joo; Lee, Joongyub

2018-05-23

Zolpidem is one of the most frequently used hypnotics worldwide, but associations with serious adverse effects such as motor vehicle collisions have been reported. The objective of this study was to evaluate the association of fatal motor vehicle collisions with a prescription for zolpidem, considering the context of the motor vehicle collisions. We conducted a case-crossover study, where each case served as its own control, by linking data about fatal motor vehicle collisions from the Korean Road Traffic Authority between 2010 and 2014 with national health insurance data. The case period was defined as 1 day before the fatal motor vehicle collisions, and was matched to four control periods at 90-day intervals. Conditional logistic regression was performed to calculate the odds ratio for fatal motor vehicle collisions associated with zolpidem exposure, and odds ratios were adjusted for time-varying exposure to confounding medications. A stratified analysis was performed by age group (younger than 65 years or not), the Charlson Comorbidity Index, and whether patients were new zolpidem users. Among the 714 subjects, the adjusted odds ratio for a fatal motor vehicle collision associated with a prescription for zolpidem the previous day was 1.48 (95% confidence interval 1.06-2.07). After stratification, a significantly increased risk was observed in subjects with a high Charlson Comorbidity Index (odds ratio 1.81; 95% confidence interval 1.16-2.84), the younger age group (odds ratio: 1.62; 95% confidence interval 1.03-2.56), and new zolpidem users (odds ratio 2.37; 95% confidence interval 1.40-4.00). A prescription for zolpidem on the previous day was significantly related to an increased risk of fatal motor vehicle collisions in this population-based case-crossover study.

Semiparametric time varying coefficient model for matched case-crossover studies.

PubMed

Ortega-Villa, Ana Maria; Kim, Inyoung; Kim, H

2017-03-15

In matched case-crossover studies, it is generally accepted that the covariates on which a case and associated controls are matched cannot exert a confounding effect on independent predictors included in the conditional logistic regression model. This is because any stratum effect is removed by the conditioning on the fixed number of sets of the case and controls in the stratum. Hence, the conditional logistic regression model is not able to detect any effects associated with the matching covariates by stratum. However, some matching covariates such as time often play an important role as an effect modification leading to incorrect statistical estimation and prediction. Therefore, we propose three approaches to evaluate effect modification by time. The first is a parametric approach, the second is a semiparametric penalized approach, and the third is a semiparametric Bayesian approach. Our parametric approach is a two-stage method, which uses conditional logistic regression in the first stage and then estimates polynomial regression in the second stage. Our semiparametric penalized and Bayesian approaches are one-stage approaches developed by using regression splines. Our semiparametric one stage approach allows us to not only detect the parametric relationship between the predictor and binary outcomes, but also evaluate nonparametric relationships between the predictor and time. We demonstrate the advantage of our semiparametric one-stage approaches using both a simulation study and an epidemiological example of a 1-4 bi-directional case-crossover study of childhood aseptic meningitis with drinking water turbidity. We also provide statistical inference for the semiparametric Bayesian approach using Bayes Factors. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Short-term effects of floods on Japanese encephalitis in Nanchong, China, 2007-2012: A time-stratified case-crossover study.

PubMed

Zhang, Feifei; Liu, Zhidong; Zhang, Caixia; Jiang, Baofa

2016-09-01

This time-stratified case-crossover study aimed to quantify the impact of floods on daily Japanese encephalitis (JE) cases from 2007 to 2012 in Nanchong city of Sichuan Province, China. Using conditional logistic regression analysis, we calculated the odds ratios (ORs) and 95% confidence intervals (CIs) at different lagged days, adjusting for daily average temperature (AT) and daily average relative humidity (ARH). A total of 370 JE cases were notified during the study period, with the median patient age being 4.2years. The seasonal pattern of JE cases clustered in July and August during the study period. Floods were significantly associated with an increased number of JE cases from lag 23 to lag 24, with the strongest lag effect at lag 23 (OR=2.00, 95% CI: 1.14-3.52). Similarly, AT and ARH were positively associated with daily JE cases from lag 0 to lag 8 and from lag 0 to lag 9, respectively. Floods, with AT and ARH, can be used to forecast JE outbreaks in the study area. Based on the results of this study, recommendations include undertaking control measures before the number of cases increases, especially for regions with similar geographic, climatic, and socio-economic conditions as those in the study area. Copyright © 2016 Elsevier B.V. All rights reserved.

Sample size calculations for cluster randomised crossover trials in Australian and New Zealand intensive care research.

PubMed

Arnup, Sarah J; McKenzie, Joanne E; Pilcher, David; Bellomo, Rinaldo; Forbes, Andrew B

2018-06-01

The cluster randomised crossover (CRXO) design provides an opportunity to conduct randomised controlled trials to evaluate low risk interventions in the intensive care setting. Our aim is to provide a tutorial on how to perform a sample size calculation for a CRXO trial, focusing on the meaning of the elements required for the calculations, with application to intensive care trials. We use all-cause in-hospital mortality from the Australian and New Zealand Intensive Care Society Adult Patient Database clinical registry to illustrate the sample size calculations. We show sample size calculations for a two-intervention, two 12-month period, cross-sectional CRXO trial. We provide the formulae, and examples of their use, to determine the number of intensive care units required to detect a risk ratio (RR) with a designated level of power between two interventions for trials in which the elements required for sample size calculations remain constant across all ICUs (unstratified design); and in which there are distinct groups (strata) of ICUs that differ importantly in the elements required for sample size calculations (stratified design). The CRXO design markedly reduces the sample size requirement compared with the parallel-group, cluster randomised design for the example cases. The stratified design further reduces the sample size requirement compared with the unstratified design. The CRXO design enables the evaluation of routinely used interventions that can bring about small, but important, improvements in patient care in the intensive care setting.

Tranexamic acid therapy in ulcerative colitis

PubMed Central

Hollanders, D.; Thomson, Jean M.; Schofield, Phillip F.

1982-01-01

The antifibrinolytic drug tranexamic acid was assessed in controlling bleeding in 12 patients with left-sided proctocolitis. The study was designed as a double-blind cross-over trial employing a dose of 4·5 g of tranexamic acid/day together with identical placebo. A statistically significant reduction in rectal bleeding was achieved in 50% of cases with a minimum of side effects. Sigmoidoscopic grading of rectal mucosal appearances was improved. Frequency of diarrhoea and stool consistency were not altered. Tranexamic acid may have a part to play in the management of selected patients with ulcerative colitis in whom bleeding is difficult to control with orthodox treatment. PMID:6980404

Comparisons on Efficacy of Elcatonin and Limaprost Alfadex in Patients with Lumbar Spinal Stenosis and Concurrent Osteoporosis: A Preliminary Study Using a Crossover Design

PubMed Central

Imajo, Yasuaki; Suzuki, Hidenori; Yoshida, Yuichiro; Taguchi, Toshihiko; Tominaga, Toshikatsu; Toyoda, Koichiro

2014-01-01

Study Design Multicenter prospective study with a crossover design. Purpose The objective of this study is to compare the efficacy of limaprost alfadex (LP) and elcatonin (EL) for lumbar spinal stenosis (LSS) patients with concurrent osteoporosis. Overview of Literature It has been increasingly important to improve quality of life by establishing appropriate conservative treatments for LSS patients with concurrent osteoporosis who will presumably continue to increase due to the percentage of the aging elevations, however there is no prospective study. Methods A total of 19 patients with LSS and concurrent osteoporosis were enrolled in this study. The patients were divided into two groups and compared using a crossover design. The Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ) and short-form (SF)-8 health survey scale were used for clinical evaluations. Results There was a significant improvement of buttock-leg pain and numbness in the EL group. A significant improvement of impaired walking function was noted for the LP group according to the JOABPEQ while the rest of the items in the JOABPEQ showed no significant differences. The SF-8 health survey revealed that somatic pains and physical summary scores in the EL group and physical functioning and physical summary scores in the LP group tended to improve but not to any statistically significant extents. Conclusions Concomitant uses of EL may be useful in patients who do not respond satisfactorily to the treatments of LP for 6-8 weeks. PMID:25187864

Triggers for an episode of sudden onset low back pain: study protocol

PubMed Central

2012-01-01

Background Most research on risk factors for low back pain has focused on long term exposures rather than factors immediately preceding the onset of low back pain. The aim of this study is to quantify the transient increase in risk of a sudden episode of low back pain associated with acute exposure to a range of common physical and psychological factors. Methods/design This study uses a case-crossover design. One thousand adults with a sudden onset of low back pain presenting to primary care clinicians will be recruited. Basic demographic and clinical information including exposure to putative triggers will be collected using a questionnaire. These triggers include exposure to hazardous manual tasks, physical activity, a slip/trip or fall, consumption of alcohol, sexual activity, being distracted, and being fatigued or tired. Exposures in the case window (0-2 hours from the time when participants first notice their back pain) will be compared to exposures in two control time-windows (one 24-26 hours and another 48-50 hours before the case window). Discussion The completion of this study will provide the first-research based estimates of the increase in risk of a sudden episode of acute low back pain associated with transient exposure to a range of common factors thought to trigger low back pain. PMID:22273001

Acute effects of urban and industrial pollution in a government-designated "Environmental risk area": the case of Brindisi, Italy.

PubMed

Gianicolo, Emilio Antonio Luca; Bruni, Antonella; Mangia, Cristina; Cervino, Marco; Vigotti, Maria Angela

2013-01-01

Exposure to air pollutants has been associated with increased hospital admissions (HAs) for respiratory and cardiovascular diseases. This work describes a short-term epidemiological study in Brindisi, a highly industrialized town in Southern Italy. The effects of daily exposure to PM10 and NO2 on daily HAs for cardiac, respiratory, and cerebrovascular diseases were investigated by means of a case-crossover design in the period 2001-2007. Results showed positive associations between PM10 and HAs for cardiac and respiratory diseases and between NO2 and HAs for all the categories of diseases considered, particularly among females. Although not statistically significant, increased risk was observed for wind blowing from the port and the industrial area. Findings confirm the health risks associated with ambient air pollution exposure, even though NO2 and PM10 concentrations were below the legal limits. This may be due to the complex scenario of emissions in the area, which should be better investigated.

Energy expenditure in people with transtibial amputation walking with crossover and energy storing prosthetic feet: A randomized within-subject study.

PubMed

McDonald, Cody L; Kramer, Patricia A; Morgan, Sara J; Halsne, Elizabeth G; Cheever, Sarah M; Hafner, Brian J

2018-05-01

Energy storing feet are unable to reduce the energy required for normal locomotion among people with transtibial amputation. Crossover feet, which incorporate aspects of energy storing and running specific feet, are designed to maximize energy return while providing stability for everyday activities. Do crossover prosthetic feet reduce the energy expenditure of walking across a range of speeds, when compared with energy storing feet among people with transtibial amputation due to non-dysvascular causes? A randomized within-subject study was conducted with a volunteer sample of twenty-seven adults with unilateral transtibial amputation due to non-dysvascular causes. Participants were fit with two prostheses. One had an energy storing foot (Össur Variflex) and the other a crossover foot (Össur Cheetah Xplore). Other components, including sockets, suspension, and interface were standardized. Energy expenditure was measured with a portable respirometer (Cosmed K4b2) while participants walked on a treadmill at self-selected slow, comfortable, and fast speeds with each prosthesis. Gross oxygen consumption rates (VO 2  ml/min) were compared between foot conditions. Energy storing feet were used as the baseline condition because they are used by most people with a lower limb prosthesis. Analyses were performed to identify people who may benefit from transition to crossover feet. On average, participants had lower oxygen consumption in the crossover foot condition compared to the energy storing foot condition at each self-selected walking speed, but this difference was not statistically significant. Participants with farther six-minute walk test distances, higher daily step counts, and higher Medicare Functional Classification Levels at baseline were more likely to use less energy in the crossover foot. Crossover feet may be most beneficial for people with higher activity levels and physical fitness. Further research is needed to examine the effect of crossover feet on energy expenditure during high-level activities. Copyright © 2018 Elsevier B.V. All rights reserved.

Air pollution and outpatient visits for conjunctivitis: A case-crossover study in Hangzhou, China.

PubMed

Fu, Qiuli; Mo, Zhe; Lyu, Danni; Zhang, Lifang; Qin, Zhenwei; Tang, Qiaomei; Yin, Houfa; Xu, Peiwei; Wu, Lizhi; Lou, Xiaoming; Chen, Zhijian; Yao, Ke

2017-12-01

Conjunctivitis, one of the most common ocular surface diseases, can be caused by many factors. The objective of this study was to investigate the potential association between conjunctivitis and air pollutants. Data of 9737 outpatient visits for conjunctivitis from July 1, 2014 to June 30, 2016 were obtained from the Eye Center of the Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China. The data were linked to data on the concentrations of carbon monoxide (CO), nitrogen dioxide (NO 2 ), ozone (O 3 ), sulfur dioxide (SO 2 ), and fine particulate matter with a median aerometric diameter of less than 10 and 2.5 μm (PM 10 and PM 2.5 , respectively), which were obtained from the Environmental Protection Department of Zhejiang Province. A time-stratified case-crossover study design and conditional logistic regression were applied to analyze the association between air pollutants and outpatient visits for conjunctivitis. A 10 μg/m 3 increase in PM 10 , PM 2.5 , SO 2 , NO 2 , and CO concentrations on the same day as the hospital visit or on lag days before the hospital visit date was associated with outpatient visits for conjunctivitis. The strongest association was observed between SO 2 and conjunctivitis patients aged 2-5 years. Variation occurs between warm and cold seasons, between genders, and among different age groups. Our study provided evidence that outpatient visits for conjunctivitis were significantly associated with air pollution in Hangzhou, China. Copyright © 2017 Elsevier Ltd. All rights reserved.

Skating crossovers on a motorized flywheel: a preliminary experimental design to test effect on speed and on crossovers.

PubMed

Smith, Aynsley M; Krause, David A; Stuart, Michael J; Montelpare, William J; Sorenson, Matthew C; Link, Andrew A; Gaz, Daniel V; Twardowski, Casey P; Larson, Dirk R; Stuart, Michael B

2013-12-01

Ice hockey requires frequent skater crossovers to execute turns. Our investigation aimed to determine the effectiveness of training crossovers on a motorized, polyethylene high-resistance flywheel. We hypothesized that high school hockey players training on the flywheel would perform as well as their peers training on ice. Participants were 23 male high-school hockey players (age 15-19 years). The study used an experimental prospective design to compare players who trained for 9 sessions on the 22-foot flywheel with players who trained for 9 sessions on a similarly sized on-ice circle. Both groups were compared with control subjects who were randomly selected from the same participant pool as those training on ice. All players were tested before and after their 3-week training regimens, and control subjects were asked to not practice crossovers between testing. Group 1 trained in a hockey training facility housing the flywheel, and group 2 trained in the ice hockey arena where testing occurred. Primary outcome measures tested in both directions were: (a) speed (time in seconds) required to skate crossovers for 3 laps of a marked face-off circle, (b) cadence of skating crossovers on the similarly sized circles, and (c) a repeat interval speed test, which measures anaerobic power. No significant changes were found between groups in on-ice testing before and after training. Among the group 1 players, 7 of 8 believed they benefited from flywheel training. Group 2 players, who trained on ice, did not improve performance significantly over group 1 players. Despite the fact that no significant on-ice changes in performance were observed in objective measures, players who trained on the flywheel subjectively reported that the flywheel is an effective cost-effective alternative to training on ice. This is a relevant finding when placed in context with limited availability of on-ice training.

Traffic-law enforcement and risk of death from motor-vehicle crashes: case-crossover study.

PubMed

Redelmeier, Donald A; Tibshirani, Robert J; Evans, Leonard

2003-06-28

Driving offences and traffic deaths are common in countries with high rates of motor-vehicle use. We tested whether traffic convictions, because of their direct effect on the recipient, might be associated with a reduced risk of fatal motor-vehicle crashes. We identified licensed drivers in Ontario, Canada, who had been involved in fatal crashes in the past 11 years. We used the case-crossover design to analyse the protective effect of recent convictions on individual drivers. 8975 licensed drivers had fatal crashes during the study period. 21501 driving convictions were recorded for all drivers from the date of obtaining a full licence to the date of fatal crash, equivalent to about one conviction per driver every 5 years. The risk of a fatal crash in the month after a conviction was about 35% lower than in a comparable month with no conviction for the same driver (95% CI 20-45, p=0.0002). The benefit lessened substantially by 2 months and was not significant by 3-4 months. The benefit was not altered by age, previous convictions, and other personal characteristics; was greater for speeding violations with penalty points than speeding violations without points; was no different for crashes of differing severity; and was not seen in drivers whose licences were suspended. Traffic-law enforcement effectively reduces the frequency of fatal motor-vehicle crashes in countries with high rates of motor-vehicle use. Inconsistent enforcement, therefore, may contribute to thousands of deaths each year worldwide.

Work-family enrichment, work-family conflict, and marital satisfaction: a dyadic analysis.

PubMed

van Steenbergen, Elianne F; Kluwer, Esther S; Karney, Benjamin R

2014-04-01

This study was designed to examine whether spouses' work-to-family (WF) enrichment experiences account for their own and their partner's marital satisfaction, beyond the effects of WF conflict. Data were collected from both partners of 215 dual-earner couples with children. As hypothesized, structural equation modeling revealed that WF enrichment experiences accounted for variance in individuals' marital satisfaction, over and above WF conflict. In line with our predictions, this positive link between individuals' WF enrichment and their marital satisfaction was mediated by more positive marital behavior, and more positive perceptions of the partner's behavior. Furthermore, evidence for crossover was found. Husbands who experienced more WF enrichment were found to show more marital positivity (according to their wives), which related to increased marital satisfaction in their wives. No evidence of such a crossover effect from wives to husbands was found. The current findings not only highlight the added value of studying positive spillover and crossover effects of work into the marriage, but also suggest that positive spillover and crossover effects on marital satisfaction might be stronger than negative spillover and crossover are. These results imply that organizational initiatives of increasing job enrichment may make employees' marital life happier and can contribute to a happy, healthy, and high-performing workforce.

Is ambient air pollution associated with onset of sudden infant death syndrome: a case-crossover study in the UK.

PubMed

Litchfield, Ian J; Ayres, Jon G; Jaakkola, Jouni J K; Mohammed, Nuredin I

2018-04-12

Air pollution has been associated with increased mortality and morbidity in several studies with indications that its effect could be more severe in children. This study examined the relationship between short-term variations in criteria air pollutants and occurrence of sudden infant death syndrome (SIDS). We used a case-crossover study design which is widely applied in air pollution studies and particularly useful for estimating the risk of a rare acute outcome associated with short-term exposure. The study used data from the West Midlands region in the UK. We obtained daily time series data on SIDS mortality (ICD-9: 798.0 or ICD-10: R95) for the period 1996-2006 with a total of 211 SIDS events. Daily counts of SIDS events. For an IQR increase in previous day pollutant concentration, the percentage increases (95% CI) in SIDS were 16 (6 to 27) for PM 10 , 1 (-7 to 10) for SO 2 , 5 (-4 to 14) for CO, -17 (-27 to -6) for O 3 , 16 (2 to 31) for NO 2 and 2 (-3 to 8) for NO after controlling for average temperature and national holidays. PM 10 and NO 2 showed relatively consistent association which persisted across different lag structures and after adjusting for copollutants. The results indicated ambient air pollutants, particularly PM 10 and NO 2 , may show an association with increased SIDS mortality. Thus, future studies are recommended to understand possible mechanistic explanations on the role of air pollution on SIDS incidence and the ways in which we might reduce pollution exposure among infants. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Comparisons on efficacy of elcatonin and limaprost alfadex in patients with lumbar spinal stenosis and concurrent osteoporosis: a preliminary study using a crossover design.

PubMed

Kanchiku, Tsukasa; Imajo, Yasuaki; Suzuki, Hidenori; Yoshida, Yuichiro; Taguchi, Toshihiko; Tominaga, Toshikatsu; Toyoda, Koichiro

2014-08-01

Multicenter prospective study with a crossover design. The objective of this study is to compare the efficacy of limaprost alfadex (LP) and elcatonin (EL) for lumbar spinal stenosis (LSS) patients with concurrent osteoporosis. It has been increasingly important to improve quality of life by establishing appropriate conservative treatments for LSS patients with concurrent osteoporosis who will presumably continue to increase due to the percentage of the aging elevations, however there is no prospective study. A total of 19 patients with LSS and concurrent osteoporosis were enrolled in this study. The patients were divided into two groups and compared using a crossover design. The Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ) and short-form (SF)-8 health survey scale were used for clinical evaluations. There was a significant improvement of buttock-leg pain and numbness in the EL group. A significant improvement of impaired walking function was noted for the LP group according to the JOABPEQ while the rest of the items in the JOABPEQ showed no significant differences. The SF-8 health survey revealed that somatic pains and physical summary scores in the EL group and physical functioning and physical summary scores in the LP group tended to improve but not to any statistically significant extents. Concomitant uses of EL may be useful in patients who do not respond satisfactorily to the treatments of LP for 6-8 weeks.

A Crossover from High Stiffness to High Hardness: The Case of Osmium and Its Borides

NASA Astrophysics Data System (ADS)

Bian, Yongming; Liu, Xiaomei; Li, Anhu; Liang, Yongcheng

2016-09-01

Transition-metal light-element compounds are currently raising great expectations for hard and superhard materials. Using the widely attracting osmium (Os) and its borides (OsB, Os2B3 and OsB2) as prototypes, we demonstrate by first-principles calculations that heavy transition metals, which possess high stiffness but low hardness, can be converted into highly hard materials by incorporating of light elements to form compounds. Such a crossover is a manifestation that the underlying sources of high stiffness and high hardness are fundamentally different. The stiffness is related to elastic deformation that is closely associated with valence electron density, whereas the hardness depends strongly on plastic deformation that is determined by bonding nature. Therefore, the incorporation of light atoms into transition metal should be a valid pathway of designing hard and superhard materials. This strategy is in principle also applicable to other transition-metal borides, carbides, and nitrides.

Efficient assessment of efficacy in post-traumatic peripheral neuropathic pain patients: pregabalin in a randomized, placebo-controlled, crossover study

PubMed Central

Jenkins, Tim M; Smart, Trevor S; Hackman, Frances; Cooke, Carol; Tan, Keith KC

2012-01-01

Background: Detecting the efficacy of novel analgesic agents in neuropathic pain is challenging. There is a critical need for study designs with the desirable characteristics of assay sensitivity, low placebo response, reliable pain recordings, low cost, short duration of exposure to test drug and placebo, and relevant and recruitable population. Methods: We designed a proof-of-concept, double-blind, randomized, placebo-controlled, crossover study in patients with post-traumatic peripheral neuropathic pain (PTNP) to evaluate whether such a study design had the potential to detect efficacious agents. Pregabalin, known to be efficacious in neuropathic pain, was used as the active analgesic. We also assessed physical activity throughout the study. Results: Twenty-five adults (20–70 years of age) with PTNP for ≥3 months entered a screening week and were then randomized to one of the two following treatment sequences: (1) pregabalin followed by placebo or (2) placebo followed by pregabalin. These 2-week treatment periods were separated by a 2-week washout period. Patients on pregabalin treatment received escalating doses to a final dosage of 300 mg/day (days 5–15). In an attempt to minimize placebo response, patients received placebo treatment during the screening week and the 2-week washout period. Average daily pain scores (primary endpoint) were significantly reduced for pregabalin versus placebo, with a mean treatment difference of −0.81 (95% confidence interval: −1.45 to −0.17; P = 0.015). Conclusion: The efficacy of pregabalin was similar to that identified in a large, parallel group trial in PTNP. Therefore, this efficient crossover study design has potential utility for future proof-of-concept studies in neuropathic pain. PMID:22888270

Factors affecting in-hospital heat-related mortality: a multi-city case-crossover analysis.

PubMed

Stafoggia, M; Forastiere, F; Agostini, D; Caranci, N; de'Donato, F; Demaria, M; Michelozzi, P; Miglio, R; Rognoni, M; Russo, A; Perucci, C A

2008-03-01

Several studies have identified strong effects of high temperatures on mortality at population level; however, individual vulnerability factors associated with heat-related in-hospital mortality are largely unknown. The objective of the study was to evaluate heat-related in-hospital mortality using a multi-city case-crossover analysis. We studied residents of four Italian cities, aged 65+ years, who died during 1997-2004. For 94,944 individuals who died in hospital and were hospitalised two or more days before death, demographics, chronic conditions, primary diagnoses of last event and hospital wards were considered. A city-specific case-crossover analysis was performed to evaluate the association between apparent temperature and mortality. Pooled odds ratios (OR) of dying on a day with a temperature of 30 degrees C compared to a day with a temperature of 20 degrees C were estimated with a random-effects meta-analysis. We estimated an overall OR of 1.32 (95% confidence interval: 1.25, 1.39). Age, marital status and hospital ward were important risk indicators. Patients in general medicine were at higher risk than those in high and intensive care units. A history of psychiatric disorders and cerebrovascular diseases gave a higher vulnerability. Mortality was greater among patients hospitalised for heart failure, stroke and chronic pulmonary diseases. In-hospital mortality is strongly associated with high temperatures. A comfortable temperature in hospitals and increased attention to vulnerable patients during heatwaves, especially in general medicine, are necessary preventive measures.

Interaction between air pollution exposure and genes in relation to levels of inflammatory markers and risk of myocardial infarction

PubMed Central

Panasevich, Sviatlana; Leander, Karin; Ljungman, Petter; Bellander, Tom; de Faire, Ulf; Pershagen, Göran; Nyberg, Fredrik

2013-01-01

Objectives Air pollution exposure induces cardiovascular effects, possibly via systemic inflammation and coagulation misbalance. Genetic variation may determine individual susceptibility. Our aim was to investigate effect modification by inflammation (Interleukin6 (IL6), tumour necrosis factor-α (TNF-α)) and coagulation (fibrinogen Bβ, plasminogen activator inhibitor-1 (PAI-1)) gene variants on the effect of long-term or short-term air pollution exposure on both blood marker levels and non-fatal myocardial infarction (MI) risk. Design Population-based case–control study with a nested case-crossover study. Gene-environment interactions for short-term and long-term air pollution on blood marker levels were studied in population controls, for long-term exposure on MI risk using case–control design, and for short-term exposure on MI onset using case-crossover design. Setting The Stockholm Heart Epidemiology Programme (SHEEP) conducted in 1992–1994 in Stockholm, Sweden. Spatial modelling was used to assess long-term (up to 30 years retrospectively) air pollution exposure to traffic-NO2 and heating-SO2 emissions at home addresses. Urban background NO2, SO2, PM10 and O3 measurements were used to estimate short-term (up to 5 days) air pollution exposure. Participants 1192 MI cases and 1506 population controls aged 45–70 years. Outcomes The levels of blood markers of inflammation (IL-6, TNF-α) and coagulation (fibrinogen, PAI-1) and MI risk. Results We observed gene–environment interaction for several IL6 and TNF SNPs in relation to inflammation blood marker levels. One-year traffic-NO2 exposure was associated with higher IL-6 levels with each additional IL6-174C allele, and 1-year heating-SO2 exposure with higher levels of TNF-α in TNF-308AA homozygotes versus −308G carriers. Short-term air pollution exposure also interacted with IL6 and TNF in relation to marker levels. The risk of MI followed the effect on blood markers in each genotype group. Conclusions Genetic variants in IL6 and TNF may modify effects of long-term and short-term air pollution exposure on inflammatory marker levels and MI risk. PMID:24056475

A case-crossover study of alcohol consumption, meals and the risk of road traffic crashes

PubMed Central

Di Bartolomeo, Stefano; Valent, Francesca; Sbrojavacca, Rodolfo; Marchetti, Riccardo; Barbone, Fabio

2009-01-01

Background The case-crossover (CC) design has proved effective to investigate the association between alcohol use and injuries in general, but has never been applied to study alcohol use and road traffic crashes (RTCs) specifically. This study aims at investigating the association between alcohol and meal consumption and the risk of RTCs using intrapersonal comparisons of subjects while driving. Methods Drivers admitted to an Italian emergency room (ER) after RTCs in 2007 were interviewed about personal, vehicle, and crash characteristics as well as hourly patterns of driving, and alcohol and food intake in the 24 hours before the crash. The odds ratio (OR) of a RTC was estimated through a CC, matched pair interval approach. Alcohol and meal consumption 6 and 2 hours before the RTC (case exposure window) were compared with exposures in earlier control windows of analogous length. Results Of 574 patients enrolled, 326 (56.8%) reported previous driving from 6 to 18 hours before the RTC and were eligible for analysis. The ORs (mutually adjusted) were 2.25 (95%CI 1.11-4.57) for alcohol and 0.94 (0.47-1.88) for meals. OR for alcohol was already increased at low (1-2 units) doses - 2.17 (1.03-4.57) and the trend of increase for each unit was significant - 1.64 (95%CI 1.05-2.57). In drivers at fault the OR for alcohol was 21.22 (2.31-194.79). The OR estimate for meal consumption seemed to increase in case of previous sleep deprivation, 2.06 (0.25-17.00). Conclusion Each single unit of acute alcohol consumption increases the risk of RTCs, in contrast with the 'legal' threshold allowed in some countries. Meal consumption is not associated with RTCs, but its combined effects with sleepiness need further elucidation. PMID:19723319

Acute Respiratory Infection and Use of Nonsteroidal Anti-Inflammatory Drugs on Risk of Acute Myocardial Infarction: A Nationwide Case-Crossover Study.

PubMed

Wen, Yao-Chun; Hsiao, Fei-Yuan; Chan, K Arnold; Lin, Zhen-Fang; Shen, Li-Jiuan; Fang, Cheng-Chung

2017-02-15

Previous studies have suggested that acute respiratory infection (ARI) and nonsteroidal anti-inflammatory drugs (NSAIDs) use could trigger acute myocardial infarction (AMI). In some countries, physicians prescribe NSAIDs for patients with ARI for symptom relief. However, there is no research evaluating whether NSAIDs use during ARI episodes may increase the risk of AMI. We identified 9793 patients with an incident hospitalization of AMI (index date) between 2007 and 2011. Using case-crossover design, we compared the following exposure status between the case (1-7-day before index date) and matched control period (366-372-day before index date): NSAIDs use during ARI episodes, ARI episodes without NSAIDs use, NSAIDs use only, or no exposure. Multivariable conditional logistic regression models were used to estimate odds ratios adjusted for potential confounders. Nonsteroidal anti-inflammatory drugs use during ARI was associated with a 3.4-fold increased risk of AMI (adjusted odds ratio [aOR] = 3.41; 95% confidence interval [CI] = 2.80-4.16), ARI without NSAIDs use was associated with a 2.7-fold increased risk (aOR = 2.65; 95% CI = 2.29-3.06), and NSAIDs use only was associated with a 1.5-fold increased risk (aOR = 1.47; 95% CI = 1.33-1.62). Moreover, parenteral NSAIDs were associated with much higher risk in ARI patients (aOR = 7.22; 95% CI = 4.07-12.81). Nonsteroidal anti-inflammatory drugs use during ARI episodes, especially parenteral NSAIDs, was associated with a further increased risk of AMI. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail journals.permissions@oup.com.

Association of air pollution and use of glyceryl trinitrate against angina pectoris: a population-based case-crossover study

PubMed Central

2013-01-01

Background Ambient air pollution has been associated with increased cardiovascular morbidity and mortality. In Reykjavik, Iceland, air pollutant concentrations exceed official health limits several times every year. The aim was to study the association of concentrations of NO2, O3, PM10, and H2S in the Reykjavik capital area with the dispensing of anti-angina pectoris medication, glyceryl trinitrate to the inhabitants. Methods Data on daily dispensing of glyceryl trinitrate, were retrieved from the Icelandic Medicines Registry. Data on hourly concentrations of NO2, O3, PM10, and H2S were obtained from the Environment Agency of Iceland. A case-crossover design was used, based on the dispensing of glyceryl trinitrate to 5,246 individuals (≥18 years) between 2005 and 2009. Results For every 10 μg/m3 increase of NO2 and O3 3-day mean concentrations, the odds ratio (OR) for daily dispensing of glyceryl trinitrates was 1.136 (95% confidence intervals (CI) 1.069-1.207) and 1.094 (95% CI 1.029-1.163) at lag 0, and OR was 1.096 (95% CI 1.029-1.168) and 1.094 (95% CI 1.028-1.166) at lag 1, respectively. Conclusions These findings suggest that NO2 and O3 ambient air concentrations may adversely affect cardiovascular health, as measured by the dispensing of glyceryl trinitrates for angina pectoris. Further, the findings suggest that data on the dispensing of medication may be a valuable health indicator when studying the effect of air pollution on cardiovascular morbidity. PMID:23631813

Pressure and Temperature Sensors Using Two Spin Crossover Materials.

PubMed

Jureschi, Catalin-Maricel; Linares, Jorge; Boulmaali, Ayoub; Dahoo, Pierre Richard; Rotaru, Aurelian; Garcia, Yann

2016-02-02

The possibility of a new design concept for dual spin crossover based sensors for concomitant detection of both temperature and pressure is presented. It is conjectured from numerical results obtained by mean field approximation applied to a Ising-like model that using two different spin crossover compounds containing switching molecules with weak elastic interactions it is possible to simultaneously measure P and T. When the interaction parameters are optimized, the spin transition is gradual and for each spin crossover compounds, both temperature and pressure values being identified from their optical densities. This concept offers great perspectives for smart sensing devices.

Spin Crossover and the Magnetic P- T Phase Diagram of Hematite at High Hydrostatic Pressures and Cryogenic Temperatures

NASA Astrophysics Data System (ADS)

Gavriliuk, A. G.; Struzhkin, V. V.; Mironovich, A. A.; Lyubutin, I. S.; Troyan, I. A.; Chow, P.; Xiao, Y.

2018-02-01

The magnetic properties of the α-Fe2O3 hematite at a high hydrostatic pressure have been studied by synchrotron Mössbauer spectroscopy (nuclear forward scattering (NFS)) on iron nuclei. Time-domain NFS spectra of hematite have been measured in a diamond anvil cell in the pressure range of 0-72 GPa and the temperature range of 36-300 K in order to study the magnetic properties at a phase transition near a critical pressure of 50 GPa. In addition, Raman spectra at room temperature have been studied in the pressure range of 0-77 GPa. Neon has been used as a pressure-transmitting medium. The appearance of an intermediate electronic state has been revealed at a pressure of 48 GPa. This state is probably related to the spin crossover in Fe3+ ions at their transition from the high-spin state (HS, S = 5/2) to a low-spin one (LS, S = 1/2). It has been found that the transient pressure range of the HS-LS crossover is extended from 48 to 55 GPa and is almost independent of the temperature. This surprising result differs fundamentally from other cases of the spin crossover in Fe3+ ions observed in other crystals based on iron oxides. The transition region of spin crossover appears because of thermal fluctuations between HS and LS states in the critical pressure range and is significantly narrowed at cooling because of the suppression of thermal excitations. The magnetic P- T phase diagram of α-Fe2O3 at high pressures and low temperatures in the spin crossover region has been constructed according to the results of measurements.

The Association Between Urban Tree Cover and Gun Assault: A Case-Control and Case-Crossover Study.

PubMed

Kondo, Michelle C; South, Eugenia C; Branas, Charles C; Richmond, Therese S; Wiebe, Douglas J

2017-08-01

Green space and vegetation may play a protective role against urban violence. We investigated whether being near urban tree cover during outdoor activities was related to being assaulted with a gun. We conducted geographic information systems-assisted interviews with boys and men aged 10-24 years in Philadelphia, Pennsylvania, including 135 patients who had been shot with a firearm and 274 community controls, during 2008-2011. Each subject reported a step-by-step mapped account of where and with whom they traveled over a full day from waking until being assaulted or going to bed. Geocoded path points were overlaid on mapped layers representing tree locations and place-specific characteristics. Conditional logistic regressions were used to compare case subjects versus controls (case-control) and case subjects at the time of injury versus times earlier that day (case-crossover). When comparing cases at the time of assault to controls matched at the same time of day, being under tree cover was inversely associated with gunshot assault (odds ratio (OR) = 0.70, 95% confidence interval (CI): 0.55, 0.88), especially in low-income areas (OR = 0.69, 95% CI: 0.54, 0.87). Case-crossover models confirmed this inverse association overall (OR = 0.55, 95% CI: 0.34, 0.89) and in low-income areas (OR = 0.54, 95% CI: 0.33, 0.88). Urban greening and tree cover may hold promise as proactive strategies to decrease urban violence. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health 2017. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Sanitary Sewer Overflows and Emergency Room Visits for Gastrointestinal Illness: Analysis of Massachusetts Data, 2006–2007

PubMed Central

DeFlorio-Barker, Stephanie; Lin, Cynthia J.; Hilborn, Elizabeth D.; Wade, Timothy J.

2017-01-01

Background: Sanitary sewer overflows (SSOs) occur when untreated sewage is discharged into water sources before reaching the treatment facility, potentially contaminating the water source with gastrointestinal pathogens. Objectives: The objective of this paper is to assess associations between SSO events and rates of gastrointestinal (GI) illness in Massachusetts. Methods: A case-crossover study design was used to investigate association between SSO events and emergency room (ER) visits with a primary diagnosis of gastrointestinal (GI) illness in Massachusetts for 2006–2007. ER visits for GI were considered exposed if an SSO event occurred in the county of residence within three hazard periods, 0–4 d, 5–9 d, or 10–14 d, before the visit. A time-stratified bidirectional design was used to select control days for each ER visit on the same day of the week during the same month. Fixed effect logistic regression models were used to estimate the risk of ER visits following the SSO event. Results: During the study period, there were 270 SSO events for northeastern Massachusetts and 66,460 ER admissions with GI illness listed as the primary diagnostic code. The overall odds ratio (OR) for ER visits for GI illness was 1.09 [95% confidence interval (CI): 1.03, 1.16] in the 10–14 d period following an SSO event, with positive ORs for all age groups and for three of the four counties. The 0–4 d and 5–9 d periods following an SSO event were not associated with ER visits for GI illness overall, and associations by county or age were inconsistent. Conclusions: We demonstrated an association between SSO events and ER visits for GI illness using a case-crossover study design. In light of the aging water infrastructure in the United States and the expected increase in heavy rainfall events, our findings suggest a potential health impact associated with sewage overflows. https://doi.org/10.1289/EHP2048 PMID:29187322

Fragile to strong crossover and Widom line in supercooled water: A comparative study

NASA Astrophysics Data System (ADS)

De Marzio, Margherita; Camisasca, Gaia; Rovere, Mauro; Gallo, Paola

2018-02-01

The aim of this paper is to discuss the relationship between the dynamics and thermodynamics of water in the supercooled region. Reviewed case studies comprehend bulk water simulated with the SPC/E, TIP4P and TIP4P/2005 potentials, water at protein interfaces, and water in solution with electrolytes. Upon supercooling, the fragile to strong crossover in the α-relaxation of water is found to occur when the Widom line emanating from the liquid-liquid critical point is crossed. This appears to be a general characteristic of supercooled water, not depending on the applied interaction potential and/or different local environments.

Self-Assembling Molecular Logic Gates Based on DNA Crossover Tiles.

PubMed

Campbell, Eleanor A; Peterson, Evan; Kolpashchikov, Dmitry M

2017-07-05

DNA-based computational hardware has attracted ever-growing attention due to its potential to be useful in the analysis of complex mixtures of biological markers. Here we report the design of self-assembling logic gates that recognize DNA inputs and assemble into crossover tiles when the output signal is high; the crossover structures disassemble to form separate DNA stands when the output is low. The output signal can be conveniently detected by fluorescence using a molecular beacon probe as a reporter. AND, NOT, and OR logic gates were designed. We demonstrate that the gates can connect to each other to produce other logic functions. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Optimal design of work zone median crossovers.

DOT National Transportation Integrated Search

2010-09-01

The use of temporary median crossovers in work zones allows for the closure of one side of a multi-lane roadway while : maintaining two-way traffic on the opposite side. This process provides the ability for construction and maintenance crews : to co...

Alteration of fasting heat production during fescue toxicosis in Holstein steers

USDA-ARS?s Scientific Manuscript database

This study was designed to examine alteration of fasting heat production (FHP) during fescue toxicosis. Six ruminally cannulated Holstein steers (BW = 348±26kg) were weight matched into pairs and utilized in a two period crossover design experiment. Each period consisted of two segments, one each at...

Alteration of fasting heat production during fescue toxicosis in Holstein steers

USDA-ARS?s Scientific Manuscript database

This study was designed to examine alteration of fasting heat production (FHP) during fescue toxicosis. Six ruminally cannulated Holstein steers (BW=348 ±13 kg) were weight-matched into pairs and utilized in a two period crossover design experiment. Each period consisted of two temperature segments,...

A Multi-state Model for Designing Clinical Trials for Testing Overall Survival Allowing for Crossover after Progression

PubMed Central

Xia, Fang; George, Stephen L.; Wang, Xiaofei

2015-01-01

In designing a clinical trial for comparing two or more treatments with respect to overall survival (OS), a proportional hazards assumption is commonly made. However, in many cancer clinical trials, patients pass through various disease states prior to death and because of this may receive treatments other than originally assigned. For example, patients may crossover from the control treatment to the experimental treatment at progression. Even without crossover, the survival pattern after progression may be very different than the pattern prior to progression. The proportional hazards assumption will not hold in these situations and the design power calculated on this assumption will not be correct. In this paper we describe a simple and intuitive multi-state model allowing for progression, death before progression, post-progression survival and crossover after progression and apply this model to the design of clinical trials for comparing the OS of two treatments. For given values of the parameters of the multi-state model, we simulate the required number of deaths to achieve a specified power and the distribution of time required to achieve the requisite number of deaths. The results may be quite different from those derived using the usual PH assumption. PMID:27239255

What about the leader? Crossover of emotional exhaustion and work engagement from followers to leaders.

PubMed

Wirtz, Nina; Rigotti, Thomas; Otto, Kathleen; Loeb, Carina

2017-01-01

Although a growing body of research links leadership behavior to follower health, comparatively little is known about the health effects of being in the lead. This longitudinal study of 315 team members and 67 leaders examined the crossover of emotional exhaustion and work engagement from followers to leaders. Leader emotional self-efficacy was tested as a moderator in the crossover process. Multiple regression analyses revealed that followers' work engagement was positively related to leaders' work engagement eight months later, controlling for followers' tenure with the leader, leader gender, autonomy, workload, and work engagement at Time 1. Leaders' emotional self-efficacy did not moderate the crossover of work engagement. Followers' emotional exhaustion was not directly related to leaders' emotional exhaustion over time. We did find a significant interaction effect for follower emotional exhaustion and leader emotional self-efficacy. This study is the first to show that crossover of emotional exhaustion and work engagement can unfold over time from team members to leaders. Main theoretical implications lie in the finding that-in line with job demands-resources theory-followers' psychological states can pose a demand or resource for leaders, and influence their well-being. For practitioners, our results offer valuable insights regarding the design of organizational health interventions as well as leadership development measures. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Single-crossover recombination in discrete time.

PubMed

von Wangenheim, Ute; Baake, Ellen; Baake, Michael

2010-05-01

Modelling the process of recombination leads to a large coupled nonlinear dynamical system. Here, we consider a particular case of recombination in discrete time, allowing only for single crossovers. While the analogous dynamics in continuous time admits a closed solution (Baake and Baake in Can J Math 55:3-41, 2003), this no longer works for discrete time. A more general model (i.e. without the restriction to single crossovers) has been studied before (Bennett in Ann Hum Genet 18:311-317, 1954; Dawson in Theor Popul Biol 58:1-20, 2000; Linear Algebra Appl 348:115-137, 2002) and was solved algorithmically by means of Haldane linearisation. Using the special formalism introduced by Baake and Baake (Can J Math 55:3-41, 2003), we obtain further insight into the single-crossover dynamics and the particular difficulties that arise in discrete time. We then transform the equations to a solvable system in a two-step procedure: linearisation followed by diagonalisation. Still, the coefficients of the second step must be determined in a recursive manner, but once this is done for a given system, they allow for an explicit solution valid for all times.

A case-crossover analysis of forest fire haze events and mortality in Malaysia

NASA Astrophysics Data System (ADS)

Sahani, Mazrura; Zainon, Nurul Ashikin; Wan Mahiyuddin, Wan Rozita; Latif, Mohd Talib; Hod, Rozita; Khan, Md Firoz; Tahir, Norhayati Mohd; Chan, Chang-Chuan

2014-10-01

The Southeast Asian (SEA) haze events due to forest fires are recurrent and affect Malaysia, particularly the Klang Valley region. The aim of this study is to examine the risk of haze days due to biomass burning in Southeast Asia on daily mortality in the Klang Valley region between 2000 and 2007. We used a case-crossover study design to model the effect of haze based on PM10 concentration to the daily mortality. The time-stratified control sampling approach was used, adjusted for particulate matter (PM10) concentrations, time trends and meteorological influences. Based on time series analysis of PM10 and backward trajectory analysis, haze days were defined when daily PM10 concentration exceeded 100 μg/m3. The results showed a total of 88 haze days were identified in the Klang Valley region during the study period. A total of 126,822 cases of death were recorded for natural mortality where respiratory mortality represented 8.56% (N = 10,854). Haze events were found to be significantly associated with natural and respiratory mortality at various lags. For natural mortality, haze events at lagged 2 showed significant association with children less than 14 years old (Odd Ratio (OR) = 1.41; 95% Confidence Interval (CI) = 1.01-1.99). Respiratory mortality was significantly associated with haze events for all ages at lagged 0 (OR = 1.19; 95% CI = 1.02-1.40). Age-and-gender-specific analysis showed an incremental risk of respiratory mortality among all males and elderly males above 60 years old at lagged 0 (OR = 1.34; 95% CI = 1.09-1.64 and OR = 1.41; 95% CI = 1.09-1.84 respectively). Adult females aged 15-59 years old were found to be at highest risk of respiratory mortality at lagged 5 (OR = 1.66; 95% CI = 1.03-1.99). This study clearly indicates that exposure to haze events showed immediate and delayed effects on mortality.

Crossover between structured and well-mixed networks in an evolutionary prisoner's dilemma game

NASA Astrophysics Data System (ADS)

Dai, Qionglin; Cheng, Hongyan; Li, Haihong; Li, Yuting; Zhang, Mei; Yang, Junzhong

2011-07-01

In a spatial evolutionary prisoner’s dilemma game (PDG), individuals interact with their neighbors and update their strategies according to some rules. As is well known, cooperators are destined to become extinct in a well-mixed population, whereas they could emerge and be sustained on a structured network. In this work, we introduce a simple model to investigate the crossover between a structured network and a well-mixed one in an evolutionary PDG. In the model, each link j is designated a rewiring parameter τj, which defines the time interval between two successive rewiring events for link j. By adjusting the rewiring parameter τ (the mean time interval for any link in the network), we could change a structured network into a well-mixed one. For the link rewiring events, three situations are considered: one synchronous situation and two asynchronous situations. Simulation results show that there are three regimes of τ: large τ where the density of cooperators ρc rises to ρc,∞ (the value of ρc for the case without link rewiring), small τ where the mean-field description for a well-mixed network is applicable, and moderate τ where the crossover between a structured network and a well-mixed one happens.

A powerful test for Balaam's design.

PubMed

Mori, Joji; Kano, Yutaka

2015-01-01

The crossover trial design (AB/BA design) is often used to compare the effects of two treatments in medical science because it performs within-subject comparisons, which increase the precision of a treatment effect (i.e., a between-treatment difference). However, the AB/BA design cannot be applied in the presence of carryover effects and/or treatments-by-period interaction. In such cases, Balaam's design is a more suitable choice. Unlike the AB/BA design, Balaam's design inflates the variance of an estimate of the treatment effect, thereby reducing the statistical power of tests. This is a serious drawback of the design. Although the variance of parameter estimators in Balaam's design has been extensively studied, the estimators of the treatment effect to improve the inference have received little attention. If the estimate of the treatment effect is obtained by solving the mixed model equations, the AA and BB sequences are excluded from the estimation process. In this study, we develop a new estimator of the treatment effect and a new test statistic using the estimator. The aim is to improve the statistical inference in Balaam's design. Simulation studies indicate that the type I error of the proposed test is well controlled, and that the test is more powerful and has more suitable characteristics than other existing tests when interactions are substantial. The proposed test is also applied to analyze a real dataset. Copyright © 2015 John Wiley & Sons, Ltd.

The administration to Indonesians of monosodium L-glutamate in Indonesian foods: an assessment of adverse reactions in a randomized double-blind, crossover, placebo-controlled study.

PubMed

Prawirohardjono, W; Dwiprahasto, I; Astuti, I; Hadiwandowo, S; Kristin, E; Muhammad, M; Kelly, M F

2000-04-01

Monosodium L-glutamate (MSG) has been suggested to cause postprandial symptoms after the ingestion of Chinese or oriental meals. Therefore, we examined whether such symptoms could be elicited in Indonesians ingesting levels of MSG typically found in Indonesian cuisine. Healthy volunteers (n = 52) were treated with capsules of placebo or MSG (1.5 and 3.0 g/person) as part of a standardized Indonesian breakfast. The study used a rigorous, randomized, double-blind, crossover design. The occurrence of symptoms after MSG ingestion did not differ from that after consumption of the placebo.

Emergency room visits for acute gastrointestinal illness following flooding: A case-crossover study

EPA Science Inventory

Climate change may alter the frequency of precipitation and flooding which can increase fecal-oral transmission of acute gastrointestinal illness (AGI) through contact with contaminated items or water. Few studies have quantified the risk associated with flood events in the Unite...

Development of a fescue toxicosis model using a fescue seed extract

USDA-ARS?s Scientific Manuscript database

This study was designed to examine the efficacy of a fescue seed extract for inducing fescue toxicosis in cattle. Four growing Holstein steers (BW = 309±36kg) surgically fitted with ruminal cannulas were utilized in a four phase crossover design experiment. The basal diet consisted of endophyte fr...

Density and spin modes in imbalanced normal Fermi gases from collisionless to hydrodynamic regime

NASA Astrophysics Data System (ADS)

Narushima, Masato; Watabe, Shohei; Nikuni, Tetsuro

2018-03-01

We study the mass- and population-imbalance effect on density (in-phase) and spin (out-of-phase) collective modes in a two-component normal Fermi gas. By calculating the eigenmodes of the linearized Boltzmann equation as well as the density/spin dynamic structure factor, we show that mass- and population-imbalance effects offer a variety of collective mode crossover behaviors from collisionless to hydrodynamic regimes. The mass-imbalance effect shifts the crossover regime to the higher-temperature, and a significant peak of the spin dynamic structure factor emerges only in the collisionless regime. This is in contrast to the case of mass- and population-balanced normal Fermi gases, where the spin dynamic response is always absent. Although the population-imbalance effect does not shift the crossover regime, the spin dynamic structure factor survives both in the collisionless and hydrodynamic regimes.

Melting of Boltzmann particles in different 2D trapping potential

NASA Astrophysics Data System (ADS)

Bhattacharya, Dyuti; Filinov, Alexei; Ghosal, Amit; Bonitz, Michael

2015-03-01

We analyze the quantum melting of two dimensional Wigner solid in several confined geometries and compare them with corresponding thermal melting in a purely classical system. Our results show that the geometry play little role in deciding the crossover quantum parameter nX, as the effects from boundary is well screened by the quantum zero point motion. The unique phase diagram in the plane of thermal and quantum fluctuations determined from independent melting criteria separates out the Wigner molecule ``phase'' from the classical and quantum ``liquids''. An intriguing signature of weakening liquidity with increasing temperature T have been found in the extreme quantum regime (n). This crossover is associated with production of defects, just like in case of thermal melting, though the role of them in determining the mechanism of the crossover appears different. Our study will help comprehending melting in a variety of experimental realization of confined system - from quantum dots to complex plasma.

A case-crossover study on transient risk factors of work-related eye injuries.

PubMed

Chen, S-Y; Fong, P-C; Lin, S-F; Chang, C-H; Chan, C-C

2009-08-01

To investigate modifiable risk and preventive factors of work-related eye injuries. A case-crossover study conducted to explore the associations between transient risk factors and work-related eye injuries. Patients seen at seven medical centres in Taiwan with work-related eye injuries over a 4-year period were enrolled in the study. Clinical information was collected from medical charts and detailed information on exposure to eight potentially modifiable factors during the 60 minutes prior to the occurrence of each injury, as well as during the same time interval on the last work day prior to the injury, were obtained using questionnaire surveys. Matched-pair interval analysis was adopted to assess the odds ratios (ORs) for work-related eye injuries given exposure to the eight modifiable factors. A total of 283 subjects were interviewed. Most of these injured workers were young, male, and self-employed or small enterprise workers. The most common injury type was photokeratitis (33.2%), mainly caused by welding (30.4%). The OR for a work-related eye injury was increased with the performance of an unfamiliar task (57.0), operation of a faulty tool or piece of equipment (48.5), distractions (24.0), being rushed (13.0), or fatigued (10.0), and a poor work environment (4.3). Wearing eye protection devices was found to have a significant protective effect on workers who might otherwise have been exposed to eye injuries (OR = 0.4; 95% CI 0.2 to 0.7). Potential modifiable risk and preventive factors for work-related eye injuries were identified using a case-crossover study. This information should be helpful in the development of preventive strategies.

Socioenvironmental factors associated with heat and cold-related mortality in Vadu HDSS, western India: a population-based case-crossover study

NASA Astrophysics Data System (ADS)

Ingole, Vijendra; Kovats, Sari; Schumann, Barbara; Hajat, Shakoor; Rocklöv, Joacim; Juvekar, Sanjay; Armstrong, Ben

2017-10-01

Ambient temperatures (heat and cold) are associated with mortality, but limited research is available about groups most vulnerable to these effects in rural populations. We estimated the effects of heat and cold on daily mortality among different sociodemographic groups in the Vadu HDSS area, western India. We studied all deaths in the Vadu HDSS area during 2004-2013. A conditional logistic regression model in a case-crossover design was used. Separate analyses were carried out for summer and winter season. Odds ratios (OR) and 95% confidence intervals (CI) were estimated for total mortality and population subgroups. Temperature above a threshold of 31 °C was associated with total mortality (OR 1.48, CI = 1.05-2.09) per 1 °C increase in daily mean temperature. Odds ratios were higher among females (OR 1.93; CI = 1.07-3.47), those with low education (OR 1.65; CI = 1.00-2.75), those owing larger agricultural land (OR 2.18; CI = 0.99-4.79), and farmers (OR 1.70; CI = 1.02-2.81). In winter, per 1 °C decrease in mean temperature, OR for total mortality was 1.06 (CI = 1.00-1.12) in lag 0-13 days. High risk of cold-related mortality was observed among people occupied in housework (OR = 1.09; CI = 1.00-1.19). Our study suggests that both heat and cold have an impact on mortality particularly heat, but also, to a smaller degree, cold have an impact. The effects may differ partly by sex, education, and occupation. These findings might have important policy implications in preventing heat and cold effects on particularly vulnerable groups of the rural populations in low and middle-income countries with hot semi-arid climate.

Association between mobile phone traffic volume and road crash fatalities: A population-based case-crossover study.

PubMed

Gariazzo, Claudio; Stafoggia, Massimo; Bruzzone, Silvia; Pelliccioni, Armando; Forastiere, Francesco

2018-06-01

Use of mobile phones while driving is known to cause crashes with possible fatalities. Different habits of mobile phone use might be distracting forces and display differential impacts on accident risk; the assessment of the relative importance is relevant to implement prevention, mitigation, and control measures. This study aimed to assess the relationship between the use of mobile phones at population level and road crash fatalities in large urban areas. Data on road crashes with fatalities were collected from seven Italian metropolitan areas and matched in time and space with high resolution mobile phone traffic volume data about calls, texts, Internet connections and upload/download data. A case-crossover study design was applied to estimate the relative risks of road accident for increases in each type of mobile phone traffic volumes in underlying population present in the small areas where accidents occurred. Effect modification was evaluated by weekday/weekend, hour of the day, meteorological conditions, and street densities. Positive associations between road crashes rates and the number of calls, texts, and Internet connections were found, with incremental risks of 17.2% (95% Confidence Interval [CI] 7.7, 27.6), 8.4% (CI 0.7, 16.8), and 54.6% (CI 34.0, 78.5) per increases (at 15 min intervals) of 5 calls/100 people, 3 text/100 people, and 40 connections/100 people, respectively. Small differences across cities were detected. Working days, nighttime and morning hours were associated with greater phone use and more road accidents. The relationship between mobile phone use and road fatalities at population level is strong. Strict controls on cellular phone in the vehicle may results in a large health benefit. Copyright © 2018 Elsevier Ltd. All rights reserved.

Air pollution and emergency department visits for respiratory diseases: A multi-city case crossover study.

PubMed

Szyszkowicz, Mieczysław; Kousha, Termeh; Castner, Jessica; Dales, Robert

2018-05-01

Increasing evidence suggests that ambient air pollution is a major risk factor for both acute and chronic respiratory disease exacerbations and emergencies. The objective of this study was to determine the association between ambient air pollutants and emergency department (ED) visits for respiratory conditions in nine districts across the province of Ontario in Canada. Health, air pollutant (PM 2.5 , NO 2 , O 3 , and SO 2 ), and meteorological data were retrieved from April 2004 to December 2011. Respiratory diseases were categorized as: chronic obstructive pulmonary disease (COPD, including bronchiectasis) and acute upper respiratory diseases. A case-crossover design was used to test the associations between ED visits and ambient air pollutants, stratified by sex and season. For COPD among males, positive results were observed for NO 2 with lags of 3-6 days, for PM 2.5 with lags 1-8, and for SO 2 with lags of 4-8 days. For COPD among females, positive results were observed for O 3 with lags 2-4 days, and for SO 2 among lags of 3-6 days. For upper respiratory disease emergencies among males, positive results were observed for NO 2 (lags 5-8 days), for O 3 , (lags 0-6 days), PM 2.5 (all lags), and SO 2 (lag 8), and among females, positive results were observed for NO 2 for lag 8 days, for O 3 , PM 2.5 among all lags. Our study provides evidence of the associations between short-term exposure to air pollution and increased risk of ED visits for upper and lower respiratory diseases in an environment where air pollutant concentrations are relatively low. Crown Copyright © 2018. Published by Elsevier Inc. All rights reserved.

Investigation of Sustained Detonation Devices: the Pulse Detonation Engine-Crossover System and the Rotating Detonation Engine System

NASA Astrophysics Data System (ADS)

Driscoll, Robert B.

An experimental study is conducted on a Pulse Detonation Engine-Crossover System to investigate the feasibility of repeated, shock-initiated combustion and characterize the initiation performance. A PDE-crossover system can decrease deflagration-to-detonation transition length while employing a single spark source to initiate a multi-PDE system. Visualization of a transferred shock wave propagating through a clear channel reveals a complex shock train behind the leading shock. Shock wave Mach number and decay rate remains constant for varying crossover tube geometries and operational frequencies. A temperature gradient forms within the crossover tube due to forward flow of high temperature ionized gas into the crossover tube from the driver PDE and backward flow of ionized gas into the crossover tube from the driven PDE, which can cause intermittent auto-ignition of the driver PDE. Initiation performance in the driven PDE is strongly dependent on initial driven PDE skin temperature in the shock wave reflection region. An array of detonation tubes connected with crossover tubes is developed using optimized parameters and successful operation utilizing shock-initiated combustion through shock wave reflection is achieved and sustained. Finally, an air-breathing, PDE-Crossover System is developed to characterize the feasibility of shock-initiated combustion within an air-breathing pulse detonation engine. The initiation effectiveness of shock-initiated combustion is compared to spark discharge and detonation injection through a pre-detonator. In all cases, shock-initiated combustion produces improved initiation performance over spark discharge and comparable detonation transition run-up lengths relative to pre-detonator initiation. A computational study characterizes the mixing processes and injection flow field within a rotating detonation engine. Injection parameters including reactant flow rate, reactant injection area, placement of the fuel injection, and fuel injection distribution are varied to assess the impact on mixing. Decreasing reactant injection areas improves fuel penetration into the cross-flowing air stream, enhances turbulent diffusion of the fuel within the annulus, and increases local equivalence ratio and fluid mixedness. Staggering fuel injection holes produces a decrease in mixing when compared to collinear fuel injection. Finally, emulating nozzle integration by increasing annulus back-pressure increases local equivalence ratio in the injection region due to increased convection residence time.

Increased calcium absorption from synthetic stable amorphous calcium carbonate: Double-blind randomized crossover clinical trial in post-menopausal women

USDA-ARS?s Scientific Manuscript database

Calcium supplementation is a widely recognized strategy for achieving adequate calcium intake. We designed this blinded, randomized, crossover interventional trial to compare the bioavailability of a new stable synthetic amorphous calcium carbonate (ACC) with that of crystalline calcium carbonate (C...

The role of randomized cluster crossover trials for comparative effectiveness testing in anesthesia: design of the Benzodiazepine-Free Cardiac Anesthesia for Reduction in Postoperative Delirium (B-Free) trial.

PubMed

Spence, Jessica; Belley-Côté, Emilie; Lee, Shun Fu; Bangdiwala, Shrikant; Whitlock, Richard; LeManach, Yannick; Syed, Summer; Lamy, Andre; Jacobsohn, Eric; MacIsaac, Sarah; Devereaux, P J; Connolly, Stuart

2018-07-01

Increasingly, clinicians and researchers recognize that studies of interventions need to evaluate not only their therapeutic efficacy (i.e., the effect on an outcome in ideal, controlled settings) but also their real-world effectiveness in broad, unselected patient groups. Effectiveness trials inform clinical practice by comparing variations in therapeutic approaches that fall within the standard of care. In this article, we discuss the need for studies of comparative effectiveness in anesthesia and the limitations of individual patient randomized-controlled trials in determining comparative effectiveness. We introduce the concept of randomized cluster crossover trials as a means of answering questions of comparative effectiveness in anesthesia, using the design of the Benzodiazepine-Free Cardiac Anesthesia for Reduction in Postoperative Delirium (B-Free) trial (Clinicaltrials.gov identifier NCT03053869).

Broadband Via-Less Microwave Crossover Using Microstrip-CPW Transitions

NASA Technical Reports Server (NTRS)

Stevenson, Thomas; U-Yen, Kongpop; Wollack, Edward; Moseley, Samuel; Hsieh, Wen-Ting

2011-01-01

The front-to-back interface between microstrip and CPW (coplanar waveguide) typically requires complex fabrication or has high radiation loss. The microwave crossover typically requires a complex fabrication step. The prior art in microstrip-CPW transition requires a physical vias connection between the microstrip and CPW line on a separate layer. The via-less version of this transition was designed empirically and does not have a close form solution. The prior art of the micro wave crossover requires either additional substrate or wire bond as an air bridge to isolate two microwave lines at the crossing junction. The disadvantages are high radiation loss, no analytical solution to the problem, lengthy simulation time, and complex fabrication procedures to generate air bridges or via. The disadvantage of the prior crossover is a complex fabrication procedure, which also affects the device reliability and yield. This microstrip-CPW transition is visualized as two microstrip-slotline transitions combined in a way that the radiation from two slotlines cancels each other out. The invention is designed based on analytical methods; thus, it significantly reduces the development time. The crossover requires no extra layer to cross two microwave signals and has low radiation loss. The invention is simple to fabricate and design. It produces low radiation loss and can be designed with low insertion loss, with some tradeoff with signal isolation. The microstrip-CPW transition is used as an interface to connect between the device and the circuit outside the package. The via-less microwave crossover is used to allow two signals to cross without using an extra layer or fabrication processing step to enable this function. This design allows the solution to be determined entirely though analytical techniques. In addition, a planar via-less microwave crossover using this technique was proposed. The experimental results show that the proposed crossover at 5 GHz has a minimum isolation of 32 dB. It also has low in-band insertion loss and return loss of 1.2 dB and 18 dB, respectively, over more than 44 percent of bandwidth at room temperature. This microstrip-CPW transition requires the microstrip line to be split into two sections. Each section is connected to a microstrip quarter-wavelength openended stub. A slotline is also placed perpendicular to the microstrip section. The slot is connected to a grounded-end quarter-wavelength slotline and generates a microstrip-slotline transition. When two of these sections are placed in parallel and with the microstrip section combined at transition, a microstrip- CPW transition is formed. The slotline radiation is suppressed as two slots are excited with the electric field in an opposite direction, which cancels the radiation in far field. The invention on the crossover consists of the invented microstrip-CPW transitions combined back-to-back and a microstrip low-pass filter. One signal is crossed through to the microstrip layer, while the other signal is crossed through the CPW line located on the ground plane of the microstrip line. The microstrip low-pass filter produces a narrow line at the crossing point to enhance the system isolation. It also produces broadband response in the operating frequency band. The microstrip-CPW transition allows a microwave signal to travel from microstrip line to CPW line with low radiation loss. The crossover allows two microwave signals to cross with minimal parasitic coupling.

Brand name to generic substitution of antiepileptic drugs does not lead to seizure-related hospitalization: a population-based case-crossover study.

PubMed

Polard, Elisabeth; Nowak, Emmanuel; Happe, André; Biraben, Arnaud; Oger, Emmanuel

2015-11-01

There is still controversy on brand-to-generic (B-G) antiepileptic drugs (AEDs) substitution. To assess association between B-G AED substitution and seizure-related hospitalization, we designed a case crossover using the French National Health Insurance Database. We identified a cohort of adult patients who filled a prescription in 2009-2011 for AEDs with at least one brand name and one generic form. The outcome date was defined as the date of hospitalization, coded G40.x or G41.x, with a G40/G41 hospitalization-free period of at least 1 year. Patients with a medical history of cancer and women who gave birth in 2009-2011 were excluded. We required individuals to have regular dispensations of AEDs within the year preceding the outcome date. Free patients were defined as patients who had only brand name dispensations before the control period. Eight thousand three hundred seventy nine patients (mean age ± standard deviation, 52.7 ± 18.8 years; sex ratio male/female, 1.27) were analyzed. Discordant pairs were 491 with B-G substitution in the control period only and 478 with B-G substitution in the case period only; odds ratio (95% confidence interval) 0.97 (0.86-1.10). No statistically significant interaction was detected among the four prespecified subgroup analyses (gender, age strata, free or non-free, and strict AED monotherapy or not). Controlling for non-seizure-related hospitalizations made no material difference. Sensitivity analyses yielded similar results. Brand-to-generic AED substitution was not associated with an elevated risk of seizure-related hospitalization. Copyright © 2015 John Wiley & Sons, Ltd.

Work-related psychosocial events as triggers of sick leave--results from a Swedish case-crossover study.

PubMed

Hultin, Hanna; Hallqvist, Johan; Alexanderson, Kristina; Johansson, Gun; Lindholm, Christina; Lundberg, Ingvar; Möller, Jette

2011-03-23

Although illness is an important cause of sick leave, it has also been suggested that non-medical risk factors may influence this association. If such factors impact on the period of decision making, they should be considered as triggers. Yet, there is no empirical support available.The aim was to investigate whether recent exposure to work-related psychosocial events can trigger the decision to report sick when ill. A case-crossover design was applied to 546 sick-leave spells, extracted from a Swedish cohort of 1430 employees with a 3-12 month follow-up of new sick-leave spells. Exposure in a case period corresponding to an induction period of one or two days was compared with exposure during control periods sampled from workdays during a two-week period prior to sick leave for the same individual. This was done according to the matched-pair interval and the usual frequency approaches. Results are presented as odds ratios (OR) with 95% confidence intervals (CI). Most sick-leave spells happened in relation to acute, minor illnesses that substantially reduced work ability. The risk of taking sick leave was increased when individuals had recently been exposed to problems in their relationship with a superior (OR 3.63; CI 1.44-9.14) or colleagues (OR 4.68; CI 1.43-15.29). Individuals were also more inclined to report sick on days when they expected a very stressful work situation than on a day when they were not under such stress (OR 2.27; CI 1.40-3.70). Exposure to problems in workplace relationships or a stressful work situation seems to be able to trigger reporting sick. Psychosocial work-environmental factors appear to have a short-term effect on individuals when deciding to report sick.

Speed behaviour in work zone crossovers. A driving simulator study.

PubMed

Domenichini, Lorenzo; La Torre, Francesca; Branzi, Valentina; Nocentini, Alessandro

2017-01-01

Reductions in speed and, more critically, in speed variability between vehicles are considered an important factor to reduce crash risk in work zones. This study was designed to evaluate in a virtual environment the drivers' behaviour in response to nine different configurations of a motorway crossover work zone. Specifically, the speed behaviour through a typical crossover layout, designed in accordance with the Italian Ministerial Decree 10 July 2002, was compared with that of eight alternative configurations which differ in some characteristics such as the sequence of speed limits, the median opening width and the lane width. The influence of variable message signs, of channelizing devices and of perceptual treatments based on Human Factor principles were also tested. Forty-two participants drove in driving simulator scenarios while data on their speeds and decelerations were collected. The results indicated that drivers' speeds are always higher than the temporary posted speed limits for all configurations and that speeds decreases significantly only within the by-passes. However the implementation of higher speed limits, together with a wider median opening and taller channelization devices led to a greater homogeneity of the speeds adopted by the drivers. The presence of perceptual measures generally induced both the greatest homogenization of speeds and the largest reductions in mean speed values. Copyright © 2016 Elsevier Ltd. All rights reserved.

Pairwise Maximum Entropy Models for Studying Large Biological Systems: When They Can Work and When They Can't

PubMed Central

Roudi, Yasser; Nirenberg, Sheila; Latham, Peter E.

2009-01-01

One of the most critical problems we face in the study of biological systems is building accurate statistical descriptions of them. This problem has been particularly challenging because biological systems typically contain large numbers of interacting elements, which precludes the use of standard brute force approaches. Recently, though, several groups have reported that there may be an alternate strategy. The reports show that reliable statistical models can be built without knowledge of all the interactions in a system; instead, pairwise interactions can suffice. These findings, however, are based on the analysis of small subsystems. Here, we ask whether the observations will generalize to systems of realistic size, that is, whether pairwise models will provide reliable descriptions of true biological systems. Our results show that, in most cases, they will not. The reason is that there is a crossover in the predictive power of pairwise models: If the size of the subsystem is below the crossover point, then the results have no predictive power for large systems. If the size is above the crossover point, then the results may have predictive power. This work thus provides a general framework for determining the extent to which pairwise models can be used to predict the behavior of large biological systems. Applied to neural data, the size of most systems studied so far is below the crossover point. PMID:19424487

Differential Impact of Unguided versus Guided Use of a Multimedia Introduction to Equine Obstetrics in Veterinary Education

ERIC Educational Resources Information Center

Govaere Jan, L. J.; de Kruif, Aart; Valcke, Martin

2012-01-01

In view of supporting the study of the complex domain of equine obstetrics, a Foal"in"Mare multimedia package with 3D designs has been developed. The present study centers on questions as to the most optimal implementation of the multimedia package in veterinary education. In a pretest-posttest cross-over design, students were randomly assigned to…

Treadmill training with partial body weight support compared with conventional gait training for low-functioning children and adolescents with nonspastic cerebral palsy: a two-period crossover study.

PubMed

Su, Ivan Y W; Chung, Kenny K Y; Chow, Daniel H K

2013-12-01

Partial body weight-supported treadmill training has been shown to be effective in gait training for patients with neurological disorders such as spinal cord injuries and stroke. Recent applications on children with cerebral palsy were reported, mostly on spastic cerebral palsy with single subject design. There is lack of evidence on the effectiveness of such training for nonspastic cerebral palsy, particularly those who are low functioning with limited intellectual capacity. This study evaluated the effectiveness of partial body weight-supported treadmill training for improving gross motor skills among these clients. A two-period randomized crossover design with repeated measures. A crossover design following an A-B versus a B-A pattern was adopted. The two training periods consisted of 12-week partial body weight-supported treadmill training (Training A) and 12-week conventional gait training (Training B) with a 10-week washout in between. Ten school-age participants with nonspastic cerebral palsy and severe mental retardation were recruited. The Gross Motor Function Measure-66 was administered immediately before and after each training period. Significant improvements in dimensions D and E of the Gross Motor Function Measure-66 and the Gross Motor Ability Estimator were obtained. Our findings revealed that the partial body weight-supported treadmill training was effective in improving gross motor skills for low-functioning children and adolescents with nonspastic cerebral palsy. .

Effect of fescue toxicosis on ruminal kinetics, nitrogen and energy balance in Holstein steers

USDA-ARS?s Scientific Manuscript database

This study was designed to examine alteration of ruminal kinetics, as well as N and energy balance during fescue toxicosis. Six ruminally cannulated Holstein steers (BW=217 ±7 kg) were weight-matched into pairs and pair-fed throughout a cross-over design experiment with a 2x2 factorial treatment str...

Conditional Poisson models: a flexible alternative to conditional logistic case cross-over analysis.

PubMed

Armstrong, Ben G; Gasparrini, Antonio; Tobias, Aurelio

2014-11-24

The time stratified case cross-over approach is a popular alternative to conventional time series regression for analysing associations between time series of environmental exposures (air pollution, weather) and counts of health outcomes. These are almost always analyzed using conditional logistic regression on data expanded to case-control (case crossover) format, but this has some limitations. In particular adjusting for overdispersion and auto-correlation in the counts is not possible. It has been established that a Poisson model for counts with stratum indicators gives identical estimates to those from conditional logistic regression and does not have these limitations, but it is little used, probably because of the overheads in estimating many stratum parameters. The conditional Poisson model avoids estimating stratum parameters by conditioning on the total event count in each stratum, thus simplifying the computing and increasing the number of strata for which fitting is feasible compared with the standard unconditional Poisson model. Unlike the conditional logistic model, the conditional Poisson model does not require expanding the data, and can adjust for overdispersion and auto-correlation. It is available in Stata, R, and other packages. By applying to some real data and using simulations, we demonstrate that conditional Poisson models were simpler to code and shorter to run than are conditional logistic analyses and can be fitted to larger data sets than possible with standard Poisson models. Allowing for overdispersion or autocorrelation was possible with the conditional Poisson model but when not required this model gave identical estimates to those from conditional logistic regression. Conditional Poisson regression models provide an alternative to case crossover analysis of stratified time series data with some advantages. The conditional Poisson model can also be used in other contexts in which primary control for confounding is by fine stratification.

Linear combinations come alive in crossover designs.

PubMed

Shuster, Jonathan J

2017-10-30

Before learning anything about statistical inference in beginning service courses in biostatistics, students learn how to calculate the mean and variance of linear combinations of random variables. Practical precalculus examples of the importance of these exercises can be helpful for instructors, the target audience of this paper. We shall present applications to the "1-sample" and "2-sample" methods for randomized short-term 2-treatment crossover studies, where patients experience both treatments in random order with a "washout" between the active treatment periods. First, we show that the 2-sample method is preferred as it eliminates "conditional bias" when sample sizes by order differ and produces a smaller variance. We also demonstrate that it is usually advisable to use the differences in posttests (ignoring baseline and post washout values) rather than the differences between the changes in treatment from the start of the period to the end of the period ("delta of delta"). Although the intent is not to provide a definitive discussion of crossover designs, we provide a section and references to excellent alternative methods, where instructors can provide motivation to students to explore the topic in greater detail in future readings or courses. Copyright © 2017 John Wiley & Sons, Ltd.

Diagnostic Crossover in Anorexia Nervosa and Bulimia Nervosa: Implications for DSM-V

PubMed Central

Eddy, Kamryn T.; Dorer, David J.; Franko, Debra L.; Tahilani, Kavita; Thompson-Brenner, Heather; Herzog, David B.

2011-01-01

Objective The Diagnostic and Statistical Manual of Mental Disorders (DSM) is designed primarily as a clinical tool. Yet high rates of diagnostic “crossover” among the anorexia nervosa subtypes and bulimia nervosa may reflect problems with the validity of the current diagnostic schema, thereby limiting its clinical utility. This study was designed to examine diagnostic crossover longitudinally in anorexia nervosa and bulimia nervosa to inform the validity of the DSM-IV-TR eating disorders classification system. Method A total of 216 women with a diagnosis of anorexia nervosa or bulimia nervosa were followed for 7 years; weekly eating disorder symptom data collected using the Eating Disorder Longitudinal Interval Follow-Up Examination allowed for diagnoses to be made throughout the follow-up period. Results Over 7 years, the majority of women with anorexia nervosa experienced diagnostic crossover: more than half crossed between the restricting and binge eating/purging anorexia nervosa subtypes over time; one-third crossed over to bulimia nervosa but were likely to relapse into anorexia nervosa. Women with bulimia nervosa were unlikely to cross over to anorexia nervosa. Conclusions These findings support the longitudinal distinction of anorexia nervosa and bulimia nervosa but do not support the anorexia nervosa subtyping schema. PMID:18198267

Multidimensional equilibria and their stability in copolymer-solvent mixtures

NASA Astrophysics Data System (ADS)

Glasner, Karl; Orizaga, Saulo

2018-06-01

This paper discusses localized equilibria which arise in copolymer-solvent mixtures. A free boundary problem associated with the sharp-interface limit of a density functional model is used to identify both lamellar and concentric domain patterns composed of a finite number of layers. Stability of these morphologies is studied through explicit linearization of the free boundary evolution. For the multilayered lamellar configuration, transverse instability is observed for sufficiently small dimensionless interfacial energies. Additionally, a crossover between small and large wavelength instabilities is observed depending on whether solvent-polymer or monomer-monomer interfacial energy is dominant. Concentric domain patterns resembling multilayered micelles and vesicles exhibit bifurcations wherein they only exist for sufficiently small dimensionless interfacial energies. The bifurcation of large radii vesicle solutions is studied analytically, and a crossover from a supercritical case with only one solution branch to a subcritical case with two is observed. Linearized stability of these configurations shows that azimuthal perturbation may lead to instabilities as interfacial energy is decreased.

Case Studies of Effects of Artificial Food Colors on Hyperactivity.

ERIC Educational Resources Information Center

Spring, Carl; And Others

1981-01-01

A double blind, double crossover study with six hyperactive boys (8 to 13 years old) tested B. Feingold's hypothesis that synthetic food colors cause hyperactivity in some children. All Ss were on the Feingold diet, eliminating artificial colors and flavors. The authors conclude that evidence for Feingold's hypothesis is weak. (Author)

An objective Bayesian analysis of a crossover design via model selection and model averaging.

PubMed

Li, Dandan; Sivaganesan, Siva

2016-11-10

Inference about the treatment effect in a crossover design has received much attention over time owing to the uncertainty in the existence of the carryover effect and its impact on the estimation of the treatment effect. Adding to this uncertainty is that the existence of the carryover effect and its size may depend on the presence of the treatment effect and its size. We consider estimation and testing hypothesis about the treatment effect in a two-period crossover design, assuming normally distributed response variable, and use an objective Bayesian approach to test the hypothesis about the treatment effect and to estimate its size when it exists while accounting for the uncertainty about the presence of the carryover effect as well as the treatment and period effects. We evaluate and compare the performance of the proposed approach with a standard frequentist approach using simulated data, and real data. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Pediatric emergency department visits and ambient Air pollution in the U.S. State of Georgia: a case-crossover study.

PubMed

Xiao, Qingyang; Liu, Yang; Mulholland, James A; Russell, Armistead G; Darrow, Lyndsey A; Tolbert, Paige E; Strickland, Matthew J

2016-11-25

Estimating the health effects of ambient air pollutant mixtures is necessary to understand the risk of real-life air pollution exposures. Pediatric Emergency Department (ED) visit records for asthma or wheeze (n = 148,256), bronchitis (n = 84,597), pneumonia (n = 90,063), otitis media (n = 422,268) and upper respiratory tract infection (URI) (n = 744,942) were obtained from Georgia hospitals during 2002-2008. Spatially-contiguous daily concentrations of 11 ambient air pollutants were estimated from CMAQ model simulations that were fused with ground-based measurements. Using a case-crossover study design, odds ratios for 3-day moving average air pollutant concentrations were estimated using conditional logistic regression, matching on ZIP code, day-of-week, month, and year. In multipollutant models, the association of highest magnitude observed for the asthma/wheeze outcome was with "oxidant gases" (O 3 , NO 2 , and SO 2 ); the joint effect estimate for an IQR increase of this mixture was OR: 1.068 (95% CI: 1.040, 1.097). The group of "secondary pollutants" (O 3 and the PM 2.5 components SO 4 2- , NO 3- , and NH 4+ ) was strongly associated with bronchitis (OR: 1.090, 95% CI: 1.050, 1.132), pneumonia (OR: 1.085, 95% CI: 1.047, 1.125), and otitis media (OR: 1.059, 95% CI: 1.042, 1.077). ED visits for URI were strongly associated with "oxidant gases," "secondary pollutants," and the "criteria pollutants" (O 3 , NO 2 , CO, SO 2 , and PM 2.5 ). Short-term exposures to air pollution mixtures were associated with ED visits for several different pediatric respiratory diseases.

Unemployment and initiation of psychotropic medication: a case-crossover study of 2 348 552 Norwegian employees.

PubMed

Kaspersen, Silje L; Pape, Kristine; Ose, Solveig O; Gunnell, David; Bjørngaard, Johan Håkon

2016-11-01

The study investigated initiation of psychotropic medication in relation to unemployment in the months before, during and after job loss, to detect the period of greatest risk. The Norwegian working population in 2004 (N=2 348 552) was observed from 2005 to 2010 through administrative registries linked to the Norwegian Prescription Database. A case-crossover design was used to analyse within-person relative risk of incident purchases of prescribed psychotropic drugs in relation to timing of unemployment. Control periods were defined 12, 24 and 36 months before the drug purchase. Supplementary analyses were performed on medication for cardiovascular disease, diabetes, obesity, thyroid disorder, pain and musculoskeletal conditions. Purchases of all psychotropic drugs increased 1-3 months before job loss. Antidepressants had the highest estimate in the month before job loss (OR 2.68, 95% CIs 2.39 to 3.01), followed by hypnotics/sedatives (OR 2.21, 95% CI 1.97 to 2.48), anxiolytics (OR 2.18, 95% CI 1.91 to 2.48) and antipsychotics (OR 2.09, 95% CI 1.76 to 2.48). Rises were greatest in men. Risk of starting psychotropic medication remained raised during a spell of unemployment, but returned to close-to-baseline levels following re-employment. Drugs used to treat somatic and pain conditions showed similar trends but with weaker associations. Concerns about impending unemployment may influence mental health several months prior to job loss, especially around the time of notification. The clinical implications of this might be a strengthening of preventive health initiatives early in the unemployment process. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Short-term exposure to ambient ozone and stroke hospital admission: A case-crossover analysis.

PubMed

Montresor-López, Jessica A; Yanosky, Jeff D; Mittleman, Murray A; Sapkota, Amir; He, Xin; Hibbert, James D; Wirth, Michael D; Puett, Robin C

2016-01-01

We evaluated the association between short-term exposure to ambient ozone air pollution and stroke hospital admissions among adult residents of South Carolina (SC). Data on all incident stroke hospitalizations from 2002 to 2006 were obtained from the SC Office of Research and Statistics. Ozone exposure data were obtained from the US Environmental Protection Agency's Hierarchical Bayesian Model. A semi-symmetric bidirectional case-crossover design was used to examine the association between ozone exposure on lag days 0-2 (0 to 2 days before admission) and stroke hospitalization. Conditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). No significant associations were observed between short-term ozone exposure and hospitalization for all stroke (e.g., lag day 0: OR=0.98; 95% CI=0.96, 1.00) or ischemic stroke (lag day 0: OR=0.98; 95% CI=0.96, 1.01). Risk of hospitalization for hemorrhagic stroke appeared to be higher among African Americans than European Americans; however, the majority of these associations did not reach statistical significance. Among adults in SC from 2002 to 2006, there was no evidence of an association between ozone exposure and risk of hospitalization for all stroke or ischemic stroke; however, African Americans may have an increased risk of hemorrhagic stroke.

A Comparison of Structurally Connected and Multiple Spacecraft Interferometers

NASA Technical Reports Server (NTRS)

Surka, Derek M.; Crawley, Edward F.

1996-01-01

Structurally connected and multiple spacecraft interferometers are compared in an attempt to establish the maximum baseline (referred to as the "cross-over baseline") for which it is preferable to operate a single-structure interferometer in space rather than an interferometer composed of numerous, smaller spacecraft. This comparison is made using the total launched mass of each configuration as the comparison metric. A framework of study within which structurally connected and multiple spacecraft interferometers can be compared is presented in block diagram form. This methodology is then applied to twenty-two different combinations of trade space parameters to investigate the effects of different orbits, orientations, truss materials, propellants, attitude control actuators, onboard disturbance sources, and performance requirements on the cross-over baseline. Rotating interferometers and the potential advantages of adding active structural control to the connected truss of the structurally connected interferometer are also examined. The minimum mass design of the structurally connected interferometer that meets all performance-requirements and satisfies all imposed constraints is determined as a function of baseline. This minimum mass design is then compared to the design of the multiple spacecraft interferometer. It is discovered that the design of the minimum mass structurally connected interferometer that meets all performance requirements and constraints in solar orbit is limited by the minimum allowable aspect ratio, areal density, and gage of the struts. In the formulation of the problem used in this study, there is no advantage to adding active structural control to the truss for interferometers in solar orbit. The cross-over baseline for missions of practical duration (ranging from one week to thirty years) in solar orbit is approximately 400 m for non-rotating interferometers and 650 m for rotating interferometers.

Numerically exploring the 1D-2D dimensional crossover on spin dynamics in the doped Hubbard model

DOE PAGES

Kung, Y. F.; Bazin, C.; Wohlfeld, K.; ...

2017-11-02

Using determinant quantum Monte Carlo (DQMC) simulations, we systematically study the doping dependence of the crossover from one to two dimensions and its impact on the magnetic properties of the Hubbard model. A square lattice of chains is used, in which the dimensionality can be tuned by varying the interchain coupling t ⊥. The dynamical spin structure factor and static quantities, such as the static spin susceptibility and nearest-neighbor spin correlation function, are characterized in the one- and two-dimensional limits as a benchmark. When the dimensionality is tuned between these limits, the magnetic properties, while evolving smoothly from one tomore » two dimensions, drastically change regardless of the doping level. This suggests that the spin excitations in the two-dimensional Hubbard model, even in the heavily doped case, cannot be explained using the spinon picture known from one dimension. In conclusion, the DQMC calculations are complemented by cluster perturbation theory studies to form a more complete picture of how the crossover occurs as a function of doping and how doped holes impact magnetic order.« less

Understanding the cluster randomised crossover design: a graphical illustraton of the components of variation and a sample size tutorial.

PubMed

Arnup, Sarah J; McKenzie, Joanne E; Hemming, Karla; Pilcher, David; Forbes, Andrew B

2017-08-15

In a cluster randomised crossover (CRXO) design, a sequence of interventions is assigned to a group, or 'cluster' of individuals. Each cluster receives each intervention in a separate period of time, forming 'cluster-periods'. Sample size calculations for CRXO trials need to account for both the cluster randomisation and crossover aspects of the design. Formulae are available for the two-period, two-intervention, cross-sectional CRXO design, however implementation of these formulae is known to be suboptimal. The aims of this tutorial are to illustrate the intuition behind the design; and provide guidance on performing sample size calculations. Graphical illustrations are used to describe the effect of the cluster randomisation and crossover aspects of the design on the correlation between individual responses in a CRXO trial. Sample size calculations for binary and continuous outcomes are illustrated using parameters estimated from the Australia and New Zealand Intensive Care Society - Adult Patient Database (ANZICS-APD) for patient mortality and length(s) of stay (LOS). The similarity between individual responses in a CRXO trial can be understood in terms of three components of variation: variation in cluster mean response; variation in the cluster-period mean response; and variation between individual responses within a cluster-period; or equivalently in terms of the correlation between individual responses in the same cluster-period (within-cluster within-period correlation, WPC), and between individual responses in the same cluster, but in different periods (within-cluster between-period correlation, BPC). The BPC lies between zero and the WPC. When the WPC and BPC are equal the precision gained by crossover aspect of the CRXO design equals the precision lost by cluster randomisation. When the BPC is zero there is no advantage in a CRXO over a parallel-group cluster randomised trial. Sample size calculations illustrate that small changes in the specification of the WPC or BPC can increase the required number of clusters. By illustrating how the parameters required for sample size calculations arise from the CRXO design and by providing guidance on both how to choose values for the parameters and perform the sample size calculations, the implementation of the sample size formulae for CRXO trials may improve.

Universal entanglement crossover of coupled quantum wires

NASA Astrophysics Data System (ADS)

Vasseur, Romain; Jacobsen, Jesper; Saleur, Hubert

2014-03-01

We consider the entanglement between two one-dimensional quantum wires (Luttinger Liquids) coupled by tunneling through a quantum impurity. The physics of the system involves a crossover between weak and strong coupling regimes characterized by an energy scale TB, and methods of conformal field theory therefore cannot be applied. The evolution of the entanglement in this crossover has led to many numerical studies, but has remained little understood, analytically or even qualitatively. This is, in part, due to the fact that the entanglement in this case is non-perturbative in the tunneling amplitude. We argue that the correct universal scaling form of the entanglement entropy S (for an arbitrary interval containing the impurity) is ∂S / ∂lnL = f(LTB) . In the special case where the coupling to the impurity can be refermionized, we show how the universal function f(LTB) can be obtained analytically using recent results on form factors of twist fields and a defect massless-scattering formalism. Our results are carefully checked against numerical simulations. This work was supported by the the French ANR (ANR Projet 2010 Blanc SIMI 4 : DIME), the US DOE (grant number DE-FG03-01ER45908), the Quantum Materials program of LBNL (RV) and the Institut Universitaire de France (JLJ).

Flooding and emergency room visits for gastrointestinal illness in Massachusetts: A case-crossover study.

EPA Science Inventory

Introduction: Floods and other severe weather events are anticipated to increase as a result of global climate change. Floods can lead to outbreaks of gastroenteritis and other infectious diseases due to disruption of sewage and water infrastructure and impacts on san...

Sanitary Sewer Systems and Association with Gastrointestinal Illness: A case crossover analysis of Massachusetts Data, 2006-2008

EPA Science Inventory

Sanitary sewer overflows (SSOs) occur when untreated sewage is discharged into water sources before reaching the treatment facility potentially contaminating them with gastrointestinal pathogens. Causes of SSOs include heavy rainfall and rupture/blockage of sewer lines. Few studi...

Minimalist Approach to Complexity: Templating the Assembly of DNA Tile Structures with Sequentially Grown Input Strands.

PubMed

Lau, Kai Lin; Sleiman, Hanadi F

2016-07-26

Given its highly predictable self-assembly properties, DNA has proven to be an excellent template toward the design of functional materials. Prominent examples include the remarkable complexity provided by DNA origami and single-stranded tile (SST) assemblies, which require hundreds of unique component strands. However, in many cases, the majority of the DNA assembly is purely structural, and only a small "working area" needs to be aperiodic. On the other hand, extended lattices formed by DNA tile motifs require only a few strands; but they suffer from lack of size control and limited periodic patterning. To overcome these limitations, we adopt a templation strategy, where an input strand of DNA dictates the size and patterning of resultant DNA tile structures. To prepare these templating input strands, a sequential growth technique developed in our lab is used, whereby extended DNA strands of defined sequence and length may be generated simply by controlling their order of addition. With these, we demonstrate the periodic patterning of size-controlled double-crossover (DX) and triple-crossover (TX) tile structures, as well as intentionally designed aperiodicity of a DX tile structure. As such, we are able to prepare size-controlled DNA structures featuring aperiodicity only where necessary with exceptional economy and efficiency.

Lack of Interaction between Sensing-Intuitive Learning Styles and Problem-First versus Information-First Instruction: A Randomized Crossover Trial

ERIC Educational Resources Information Center

Cook, David A.; Thompson, Warren G.; Thomas, Kris G.; Thomas, Matthew R.

2009-01-01

Background: Adaptation to learning styles has been proposed to enhance learning. Objective: We hypothesized that learners with sensing learning style would perform better using a problem-first instructional method while intuitive learners would do better using an information-first method. Design: Randomized, controlled, crossover trial. Setting:…

Impaired alcohol metabolism after gastric bypass surgery: a case-crossover trial.

PubMed

Woodard, Gavitt A; Downey, John; Hernandez-Boussard, Tina; Morton, John M

2011-02-01

Severe obesity remains the leading public health crisis of the industrialized world, with bariatric surgery the only effective and enduring treatment. Poor psychological adjustment has been occasionally reported postoperatively. In addition, evidence suggests that patients can metabolize alcohol differently after gastric bypass. Preoperatively and at 3 and 6 months postoperatively, 19 Roux-en-Y gastric bypass (RYGB) patients' breath alcohol content (BAC) was measured every 5 minutes after drinking 5 oz red wine to determine peak BAC and time until sober in a case-crossover design preoperatively and at 6 months postoperatively. Patients reported symptoms experienced when intoxicated and answered a questionnaire of drinking habits. The peak BAC in patients after RYGB was considerably higher at 3 months (0.059%) and 6 months (0.088%) postoperatively than matched preoperative levels (0.024%). Patients also took considerably more time to return to sober at 3 months (61 minutes) and 6 months (88 minutes) than preoperatively (49 minutes). Postoperative intoxication was associated with lower levels of diaphoresis, flushing, and hyperactivity and higher levels of dizziness, warmth, and double vision. Postoperative patients reported drinking considerably less alcohol, fewer preferred beer, and more preferred wine than before surgery. This is the first study to match preoperative and postoperative alcohol metabolism in gastric bypass patients. Post-RYGB patients have much higher peak BAC after ingesting alcohol and require more time to become sober. Patients who drink alcohol after gastric bypass surgery should exercise caution. Copyright © 2011 American College of Surgeons. Published by Elsevier Inc. All rights reserved.

Homing by path integration when a locomotion trajectory crosses itself.

PubMed

Yamamoto, Naohide; Meléndez, Jayleen A; Menzies, Derek T

2014-01-01

Path integration is a process with which navigators derive their current position and orientation by integrating self-motion signals along a locomotion trajectory. It has been suggested that path integration becomes disproportionately erroneous when the trajectory crosses itself. However, there is a possibility that this previous finding was confounded by effects of the length of a traveled path and the amount of turns experienced along the path, two factors that are known to affect path integration performance. The present study was designed to investigate whether the crossover of a locomotion trajectory truly increases errors of path integration. In an experiment, blindfolded human navigators were guided along four paths that varied in their lengths and turns, and attempted to walk directly back to the beginning of the paths. Only one of the four paths contained a crossover. Results showed that errors yielded from the path containing the crossover were not always larger than those observed in other paths, and the errors were attributed solely to the effects of longer path lengths or greater degrees of turns. These results demonstrated that path crossover does not always cause significant disruption in path integration processes. Implications of the present findings for models of path integration are discussed.

The association between urban tree cover and gun assault: A case-control and case-crossover study

Treesearch

Michelle C. Kondo; Eugenia C. South; Charles C. Branas; Therese S. Richmond; Douglas J. Wiebe

2017-01-01

Green space and vegetation may play a protective role against urban violence. We investigated whether being near urban tree cover during outdoor activities was related to being assaulted with a gun. We conducted geographic information systems–assisted interviews with boys andmen aged 10–24 years in Philadelphia, Pennsylvania, including 135 patients who had been shot...

Acute Low Back Pain? Do Not Blame the Weather-A Case-Crossover Study.

PubMed

Beilken, Keira; Hancock, Mark J; Maher, Chris G; Li, Qiang; Steffens, Daniel

2017-06-01

To investigate the influence of various weather parameters on the risk of developing a low back pain (LBP) episode. Case-crossover study. Primary care clinics in Sydney, Australia. 981 participants with a new episode of acute LBP. Weather parameters were obtained from the Australian Bureau of Meteorology. Odds ratios (OR) and 95% confidence intervals (95% CI) were derived comparing two exposure variables in the case window-(1) the average of the weather variable for the day prior to pain onset and (2) the change in the weather variable from 2 days prior to 1 day prior to pain onset-with exposures in two control windows (1 week and 1 month before the case window). The weather parameters of precipitation, humidity, wind speed, wind gust, wind direction, and air pressure were not associated with the onset of acute LBP. For one of the four analyses, higher temperature slightly increased the odds of pain onset. Common weather parameters that had been previously linked to musculoskeletal pain, such as precipitation, humidity, wind speed, wind gust, wind direction, and air pressure, do not increase the risk of onset for LBP. © 2016 American Academy of Pain Medicine. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com

Association of cerebrovascular events with antidepressant use: a case-crossover study.

PubMed

Wu, Chi-Shin; Wang, Sheng-Chang; Cheng, Yu-Cheng; Gau, Susan Shur-Fen

2011-05-01

The authors sought to assess the risk of cerebrovascular events associated with use of antidepressant medications. The authors conducted a case-crossover study of 24,214 patients with stroke enrolled in the National Health Insurance Research Database in Taiwan from 1998 to 2007. The authors compared the rates of antidepressant use during case and control time windows of 7, 14, and 28 days. Adjustments were made for time-dependent variables, such as health system utilization and proposed confounding medications. Stratified analyses were performed for valuing the interaction between the stroke risk of antidepressant use and age, sex, presence of mood disorder, stroke type, severity of chronic illness, and duration of antidepressant treatment. A conditional logistic regression model was used to determine the odds of antidepressant use during case time windows. The adjusted odds ratio of stroke risk with antidepressant exposure was 1.48 (95% confidence interval=1.37-1.59) using 14-day time windows. Stroke risk was negatively associated with the number of antidepressant prescriptions reported. Use of antidepressants with high inhibition of the serotonin transporter was associated with a greater risk of stroke than use of other types of antidepressants. These findings suggest that antidepressant use may be associated with an increased risk of stroke. However, the underlying mechanisms remain unclear.

It is not all bad for the grey city - A crossover study on physiological and psychological restoration in a forest and an urban environment.

PubMed

Stigsdotter, Ulrika K; Corazon, Sus Sola; Sidenius, Ulrik; Kristiansen, Jesper; Grahn, Patrik

2017-07-01

Today, urbanization presents a challenge to urban planning with regard to creating healthy living environments. The aim of this research is to gain further knowledge of the restorativeness of a best case urban and natural environment: that is a historic down town urban environment and forest environment located in an arboretum. The study has a cross-over design where 51 (N) female university students are exposed to the two environments through both seated viewing and walking. A mixed method approach is used with both physiological measurements of blood pressure (BP) and heart rate variability (HRV) and psychological measurements of mood change and perceived restorativeness. The HRV results show no significant differences between the two environments, and both environments are found to be more physiologically restorative than being at the office or on the minibus. The results of the psychological measures indicate that the forest walk has a positive effect on mood, while the walk in the urban environment has no effect. The forest environment is also rated more highly with regard to perceived restorativeness than the urban environment. The results support the current research that shows natural environments as more restorative than urban environments. The study also adds to the ongoing debate on healthy urban planning by indicating that architectural and historical qualities may be associated with the physiological well-being of citizens. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Spacer type mediated tunable spin crossover (SCO) characteristics of pyrene decorated 2,6-bis(pyrazol-1-yl)pyridine (bpp) based Fe(ii) molecular spintronic modules.

PubMed

Kumar, Kuppusamy Senthil; Šalitroš, Ivan; Moreno-Pineda, Eufemio; Ruben, Mario

2017-08-14

A simple "isomer-like" variation of the spacer group in a set of Fe(ii) spin crossover (SCO) complexes designed to probe spin state dependence of electrical conductivity in graphene-based molecular spintronic junctions led to the observation of remarkable variations in the thermal- and light-induced magnetic characteristics, paving a simple route for the design of functional SCO complexes with different temperature switching regimes based on a 2,6-bis(pyrazol-1-yl)pyridine ligand skeleton.

Winter air pollution and infant bronchiolitis in Paris.

PubMed

Ségala, Claire; Poizeau, David; Mesbah, Mounir; Willems, Sylvie; Maidenberg, Manuel

2008-01-01

Respiratory syncytial virus (RSV) is one of the most common respiratory pathogens in infants and young children. It is not known why some previously healthy infants, when in contact with RSV, develop bronchiolitis whereas others have only mild symptoms. Our study aimed to evaluate the possible association between emergency hospital visits for bronchiolitis and air pollution in the Paris region during four winter seasons. We included children under the age of 3 years who attended emergency room services for bronchiolitis (following standardized definition) during the period 1997-2001. Two series of data from 34 hospitals, the daily number of emergency hospital consultations (n=50857) and the daily number of hospitalizations (n=16588) for bronchiolitis, were analyzed using alternative statistical methods; these were the generalized additive model (GAM) and case-crossover models. After adjustments for public holidays, holidays and meteorological variables the case-crossover model showed that PM10, BS, SO2 and NO2 were positively associated with both consultations and hospitalizations. GAM models, adjusting for long-term trend, seasonality, holiday, public holiday, weekday and meteorological variables, gave similar results for SO2 and PM10. This study shows that air pollution may act as a trigger for the occurrence of acute severe bronchiolitis cases.

Integrating GIS, cellular automata, and genetic algorithm in urban spatial optimization: a case study of Lanzhou

NASA Astrophysics Data System (ADS)

Xu, Xibao; Zhang, Jianming; Zhou, Xiaojian

2006-10-01

This paper presents a model integrating GIS, cellular automata (CA) and genetic algorithm (GA) in urban spatial optimization. The model involves three objectives of the maximization of land-use efficiency, the maximization of urban spatial harmony and appropriate proportion of each land-use type. CA submodel is designed with standard Moore neighbor and three transition rules to maximize the land-use efficiency and urban spatial harmony, according to the land-use suitability and spatial harmony index. GA submodel is designed with four constraints and seven steps for the maximization of urban spatial harmony and appropriate proportion of each land-use type, including encoding, initializing, calculating fitness, selection, crossover, mutation and elitism. GIS is used to prepare for the input data sets for the model and perform spatial analysis on the results, while CA and GA are integrated to optimize urban spatial structure, programmed with Matlab 7 and coupled with GIS loosely. Lanzhou, a typical valley-basin city with fast urban development, is chosen as the case study. At the end, a detail analysis and evaluation of the spatial optimization with the model are made, and it proves to be a powerful tool in optimizing urban spatial structure and make supplement for urban planning and policy-makers.

Associations between summertime ambient pollutants and respiratory morbidity in New York City: Comparison of results using ambient concentrations versus predicted exposures

EPA Science Inventory

Epidemiological analyses of air quality often estimate human exposure from ambient monitoring data, potentially leading to exposure misclassification and subsequent bias in estimated health risks. To investigate this, we conducted a case-crossover study of summertime ambient ozon...

Uncertain Associations of Major Bleeding and Concurrent Use of Antiplatelet Agents and Chinese Medications: A Nested Case-Crossover Study

PubMed Central

Yam, Felix K.

2017-01-01

Despite the evidence that some commonly used Chinese medications (CMs) have antiplatelet/anticoagulant effects, many patients still used antiplatelets combined with CMs. We conducted a nested case-crossover study to examine the associations between the concomitant use of antiplatelets and CMs and major bleeding using population-based health database in Taiwan. Among the cohort of 79,463 outpatients prescribed antiplatelets (e.g., aspirin and clopidogrel) continuously, 1,209 patients hospitalized with new occurring bleeding in 2012 and 2013 were included. Those recruited patients served as their own controls to compare different times of exposure to prespecified CMs (e.g., Asian ginseng and dong quai) and antiplatelet agents. The periods of case, control 1, and control 2 were defined as 1–4 weeks, 6–9 weeks, and 13–16 weeks before hospitalization, respectively. Conditional logistic regression analyses found that concurrent use of antiplatelet drugs with any of the prespecified CMs in the case period might not significantly increase the risks of bleeding over that in the control periods (OR = 1.00, 95% CI 0.51 to 1.95 and OR = 1.13, 95% CI 0.65 to 1.97). The study showed no strong relationships between hospitalization for major bleeding events and concurrent use of antiplatelet drugs with the prespecified CMs. PMID:28831288

The Inverse Optimal Control Problem for a Three-Loop Missile Autopilot

NASA Astrophysics Data System (ADS)

Hwang, Donghyeok; Tahk, Min-Jea

2018-04-01

The performance characteristics of the autopilot must have a fast response to intercept a maneuvering target and reasonable robustness for system stability under the effect of un-modeled dynamics and noise. By the conventional approach, the three-loop autopilot design is handled by time constant, damping factor and open-loop crossover frequency to achieve the desired performance requirements. Note that the general optimal theory can be also used to obtain the same gain as obtained from the conventional approach. The key idea of using optimal control technique for feedback gain design revolves around appropriate selection and interpretation of the performance index for which the control is optimal. This paper derives an explicit expression, which relates the weight parameters appearing in the quadratic performance index to the design parameters such as open-loop crossover frequency, phase margin, damping factor, or time constant, etc. Since all set of selection of design parameters do not guarantee existence of optimal control law, explicit inequalities, which are named the optimality criteria for the three-loop autopilot (OC3L), are derived to find out all set of design parameters for which the control law is optimal. Finally, based on OC3L, an efficient gain selection procedure is developed, where time constant is set to design objective and open-loop crossover frequency and phase margin as design constraints. The effectiveness of the proposed technique is illustrated through numerical simulations.

Can the Farnsworth D15 Color Vision Test Be Defeated through Practice?

PubMed

Ng, Jason S; Liem, Sophia C

2018-05-01

This study suggests that it is possible for some patients with severe red-green color vision deficiency to do perfectly on the Farnsworth D15 test after practicing it. The Farnsworth D15 is a commonly used test to qualify people for certain occupations. For patients with color vision deficiency, there may be high motivation to try to pass the test through practice to gain entry into a particular occupation. There is no evidence in the literature on whether it is possible for patients to learn to pass the D15 test through practice. Ten subjects with inherited red-green color vision deficiency and 15 color-normal subjects enrolled in the study. All subjects had anomaloscope testing, color vision book tests, and a Farnsworth D15 at an initial visit. For the D15, the number of major crossovers was determined for each subject. Failing the D15 was determined as greater than 1 major crossover. Subjects with color vision deficiency practiced the D15 as long as desired to achieve a perfect score and then returned for a second visit for D15 testing. A paired t test was used to analyze the number of major crossovers at visit 1 versus visit 2. Color-normal subjects did not have any major crossovers. Subjects with color vision deficiency had significantly (P < .001) fewer major crossovers on the D15 test at visit 2 (mean/SD = 2.5/3.0), including five subjects with dichromacy that achieved perfect D15 performance, compared to visit 1 (mean/SD = 8.7/1.3). Practice of the Farnsworth D15 test can lead to perfect performance for some patients with color vision deficiency, and this should be considered in certain cases where occupational entry is dependent on D15 testing.

Assessment of levothyroxine sodium bioavailability: recommendations for an improved methodology based on the pooled analysis of eight identically designed trials with 396 drug exposures.

PubMed

Walter-Sack, Ingeborg; Clanget, Christof; Ding, Reinhard; Goeggelmann, Christoph; Hinke, Vera; Lang, Matthias; Pfeilschifter, Johannes; Tayrouz, Yorki; Wegscheider, Karl

2004-01-01

Assessment of dosage form performance in delivering endogenous compounds, such as hormones, in vivo requires a specific approach. Assessment of relative bioavailability of levothyroxine sodium (L-T4) from eight solid preparations, compared with a liquid formulation, by using pharmacological doses, and critical evaluation of trial methodology based on the pooled analysis of individual data. Eight open-label, randomised, single-dose, crossover phase I studies using eight solid L-T4 dosage forms (25, 50, 75, 100, 125, 150, 175, 200 microg per tablet; administered total doses 600, 625 or 700 microg) and a liquid formulation; assessment of relative bioavailability by 90% confidence intervals for the relative area under the concentration-time curve (AUC) of total thyroxine (TT4), i.e. protein-bound plus free thyroxine, calculated by using the recommended log AUC four-way analysis of variance models for crossover designs. For the pooled analysis, general linear models were applied to assess the validity of model assumptions, to identify potential sources of effect modification, to discuss alternative modelling approaches with respect to endogenous hormone secretion and to give recommendations for future designs and sample sizes. One hundred and sixty-nine healthy males; 29 of these individuals participating in two studies. Single oral doses of L-T4 tablets and the liquid formulation administered after fasting, separated by at least 6 weeks; a total of 396 drug exposures. TT4 AUC from 0 to 48 hours and peak plasma concentration with and without baseline correction. Each study demonstrated equivalence of the tablets to the drinking solution, independent of the chosen analysis model. Sequence effects that could devalidate the chosen crossover approach were not found. Period effects with changing directions that could best be explained by seasonal variation were detected. While the pre-specified method of baseline correction of simply subtracting individual time-zero TT4 values was disadvantageous, the analysis of total AUC could be improved considerably by covariate adjustment for baseline TT4. With this approach, sample sizes could have been substantially reduced or, alternatively, the recommended equivalence ranges could be reduced to +/-6%. Using a single pharmacological dose of L-T4 in two-period crossover designs is a safe and reliable procedure to assess L-T4 dosage form performance. With an adequate statistical modelling approach, the design is efficient and allows general conclusions with moderate sample sizes.

Testing equality and interval estimation in binary responses when high dose cannot be used first under a three-period crossover design.

PubMed

Lui, Kung-Jong; Chang, Kuang-Chao

2015-01-01

When comparing two doses of a new drug with a placebo, we may consider using a crossover design subject to the condition that the high dose cannot be administered before the low dose. Under a random-effects logistic regression model, we focus our attention on dichotomous responses when the high dose cannot be used first under a three-period crossover trial. We derive asymptotic test procedures for testing equality between treatments. We further derive interval estimators to assess the magnitude of the relative treatment effects. We employ Monte Carlo simulation to evaluate the performance of these test procedures and interval estimators in a variety of situations. We use the data taken as a part of trial comparing two different doses of an analgesic with a placebo for the relief of primary dysmenorrhea to illustrate the use of the proposed test procedures and estimators.

The impact of a multidisciplinary self-care management program on quality of life, self-care, adherence to anti-hypertensive therapy, glycemic control, and renal function in diabetic kidney disease: A Cross-over Study Protocol.

PubMed

Helou, Nancy; Talhouedec, Dominique; Shaha, Maya; Zanchi, Anne

2016-07-19

Diabetic kidney disease, a global health issue, remains associated with high morbidity and mortality. Previous research has shown that multidisciplinary management of chronic disease can improve patient outcomes. The effect of multidisciplinary self-care management on quality of life and renal function of patients with diabetic kidney disease has not yet been well established. The aim of this study is to evaluate the impact of a multidisciplinary self-care management program on quality of life, self-care behavior, adherence to anti-hypertensive treatment, glycemic control, and renal function of adults with diabetic kidney disease. A uniform balanced cross-over design is used, with the objective to recruit 40 adult participants with diabetic kidney disease, from public and private out-patient settings in French speaking Switzerland. Participants are randomized in equal number into four study arms. Each participant receives usual care alternating with the multidisciplinary self- care management program. Each treatment period lasts three months and is repeated twice at different time intervals over 12 months depending on the cross-over arm. The multidisciplinary self-care management program is led by an advanced practice nurse and adds nursing and dietary consultations and follow-ups, to the habitual management provided by the general practitioner, the nephrologist and the diabetologist. Data is collected every three months for 12 months. Quality of life is measured using the Audit of Diabetes-Dependent Quality of Life scale, patient self-care behavior is assessed using the Revised Summary of Diabetes Self-Care Activities, and adherence to anti-hypertensive therapy is evaluated using the Medication Events Monitoring System. Blood glucose control is measured by the glycated hemoglobin levels and renal function by serum creatinine, estimated glomerular filtration rate and urinary albumin/creatinine ratio. Data will be analyzed using STATA version 14. The cross-over design will elucidate the responses of individual participant to each treatment, and will allow us to better evaluate the use of such a design in clinical settings and behavioral studies. This study also explores the impact of a theory-based nursing practice and its implementation into a multidisciplinary context. ClinicalTrials.gov identifier: NCT01967901 , registered on the 18th of October 2013.

Effects of a Worksite Weight-Control Programme in Obese Male Workers: A Randomized Controlled Crossover Trial

ERIC Educational Resources Information Center

Iriyama, Yae; Murayama, Nobuko

2014-01-01

Objective: We conducted a randomized controlled crossover trial to evaluate the effects of a new worksite weight-control programme designed for men with or at risk of obesity using a combination of nutrition education and nutrition environmental interventions. Subjects and methods: Male workers with or at risk of obesity were recruited for this…

Pilot Study: EatFit Impacts Sixth Graders' Academic Performance on Achievement of Mathematics and English Education Standards

ERIC Educational Resources Information Center

Shilts, Mical Kay; Lamp, Cathi; Horowitz, Marcel; Townsend, Marilyn S.

2009-01-01

Objective: Investigate the impact of a nutrition education program on student academic performance as measured by achievement of education standards. Design: Quasi-experimental crossover-controlled study. Setting: California Central Valley suburban elementary school (58% qualified for free or reduced-priced lunch). Participants: All sixth-grade…

A Two-Study Examination of Work-Family Conflict, Production Deviance and Gender

ERIC Educational Resources Information Center

Ferguson, Merideth; Carlson, Dawn; Hunter, Emily M.; Whitten, Dwayne

2012-01-01

Building on the spillover and crossover literatures of work-family conflict and the theoretical framework of Conservation of Resources Theory (Hobfoll, 1989) we examine the effects of conflict on production deviance. Using a two-study constructive replication and extension design, we examine how partner work-to-family conflict contributes to job…

Effect of fescue toxicosis on whole body energy and nitrogen balance, in situ degradation and ruminal passage rates in Holstein steers

USDA-ARS?s Scientific Manuscript database

This study was designed to examine alteration of ruminal kinetics, as well as N and energy balance during fescue toxicosis. Six ruminally cannulated Holstein steers (BW=217 ±7 kg) were weight-matched into pairs and pair-fed throughout a cross-over design experiment with a 2x2 factorial treatment str...

Supervised Home Training of Dialogue Skills in Chronic Aphasia: A Randomized Parallel Group Study

ERIC Educational Resources Information Center

Nobis-Bosch, Ruth; Springer, Luise; Radermacher, Irmgard; Huber, Walter

2011-01-01

Purpose: The aim of this study was to prove the efficacy of supervised self-training for individuals with aphasia. Linguistic and communicative performance in structured dialogues represented the main study parameters. Method: In a cross-over design for randomized matched pairs, 18 individuals with chronic aphasia were examined during 12 weeks of…

Prescription of antiepileptics and the risk of road traffic crash.

PubMed

Orriols, Ludivine; Foubert-Samier, Alexandra; Gadegbeku, Blandine; Delorme, Bernard; Tricotel, Aurore; Philip, Pierre; Moore, Nicholas; Lagarde, Emmanuel

2013-03-01

Studies assessing the impact of epilepsy and its medication on the risk of road traffic crashes have shown inconsistent results. The aim in this study was to assess this risk using French databases. Data from three French national databases were extracted and matched: the national health care insurance database, police reports, and the national police database of injurious crashes. Only antiepileptics prescribed predominantly in epilepsy were studied (phenobarbital, phenytoin, ethosuximide, valproic acid, vigabatrin, tiagabin, levitiracetam, zonisamide, and lacosamide). A case-control analysis comparing responsible and non-responsible drivers and a case-crossover analysis were performed. Drivers (72 685) involved in an injurious crash in France between July 2005 and May 2008, were included. Drivers exposed to prescribed antiepileptic medicines (n = 251) had an increased risk of being responsible for a crash (OR 1.74 [1.29-2.34]). The association was also significant for the most severe epileptic patients (n = 99; OR = 2.20 [1.31-3.69]). Case-crossover analysis found no association between crash risk and treatment prescription. Patients with prescription of antiepileptic drugs should be cautioned about their potential risk of road traffic crash. This risk is however more likely to be related to seizures than to the effect of antiepileptic medicines. © The Author(s) 2013.

A six-month crossover chemoprevention clinical trial of tea in smokers and non-smokers: methodological issues in a feasibility study

PubMed Central

2012-01-01

Background Chemoprevention crossover trials of tea can be more efficient than parallel designs but the attrition and compliance rates with such trials are unknown. Methods Attrition (dropouts) and compliance with treatment were assessed in a 25-week randomized, placebo controlled, crossover, feasibility clinical trial of four tea treatments to investigate the effect of tea on oral cancer biomarkers. Each treatment lasted 4 weeks with 2 weeks of washout in between. Participants were 32 smokers and 33 non-smokers without any evidence of premalignant oral lesions. The interventions consisted of packets of green tea, black tea, caffeinated water, or placebo. Participants were assigned to each treatment for four weeks, and were instructed to drink five packets per day while on the treatment. Dropout from the trial and compliance (consumption of ≥ 85% of the prescribed treatment packets) are the main outcome measures reported. Results There was a high rate of dropout (51%) from the study, and the rates were significantly higher among smokers (64%) than non-smokers (36%). Among participants who completed the study the rate of compliance was 72%. The highest rates of dropouts occurred between the first and second treatment visits in both smokers (38% dropout) and non-smokers (18% dropout). Throughout the study smokers were more likely to dropout than non-smokers. Black tea treatment was associated with the highest rates of dropout among smokers (37%), but was associated with the lowest rate of dropout among non-smokers (4%). Conclusions In a study conducted to test the feasibility of a four-treatment crossover tea trial, a high rate of dropout among smokers and non-smokers was observed. Multi-arm crossover tea trials might pose a higher burden on participants and research is needed to improve adherence and treatment compliance in such trials. Trial registration number ISRCTN70410203 PMID:22800470

Hourly differences in air pollution and risk of respiratory disease in the elderly: a time-stratified case-crossover study.

PubMed

Yorifuji, Takashi; Suzuki, Etsuji; Kashima, Saori

2014-08-13

Epidemiological studies have shown adverse effects of short-term exposure to air pollution on respiratory disease outcomes; however, few studies examined this association on an hourly time scale. We evaluated the associations between hourly changes in air pollution and the risk of respiratory disease in the elderly, using the time of the emergency call as the disease onset for each case. We used a time-stratified case-crossover design. Study participants were 6,925 residents of the city of Okayama, Japan, aged 65 or above who were taken to hospital emergency rooms between January 2006 and December 2010 for onset of respiratory disease. We calculated city-representative hourly average concentrations of air pollutants from several monitoring stations. By using conditional logistic regression models, we estimated odds ratios per interquartile-range increase in each pollutant by exposure period prior to emergency call, adjusting for hourly ambient temperature, hourly relative humidity, and weekly numbers of reported influenza cases aged ≥60. Suspended particulate matter (SPM) exposure 24 to <72 hours prior to the onset and ozone exposure 48 to <96 hours prior to the onset were associated with the increased risk of respiratory disease. For example, following one interquartile-range increase, odds ratios were 1.05 (95% confidence interval: 1.01, 1.09) for SPM exposure 24 to <48 hours prior to the onset and 1.13 (95% confidence interval: 1.04, 1.23) for ozone exposure 72 to <96 hours prior to the onset. Sulfur dioxide (SO2) exposure 0 to <24 hours prior to onset was associated with the increased risk of pneumonia and influenza: odds ratio was 1.07 per one interquartile-range increase (95% confidence interval: 1.00, 1.14). Elevated risk for pneumonia and influenza of SO2 was observed at shorter lags (i.e., 8-18 hours) than the elevated risks for respiratory disease of SPM or ozone. Overall, the effect estimates for chronic obstructive pulmonary disease and allied conditions were equivocal. This study provides further evidence that hourly changes in air pollution exposure increase the risks of respiratory disease, and that SO2 may be related with more immediate onset of the disease than other pollutants.

Combining epidemiology and biomechanics in sports injury prevention research: a new approach for selecting suitable controls.

PubMed

Finch, Caroline F; Ullah, Shahid; McIntosh, Andrew S

2011-01-01

Several important methodological issues need to be considered when designing sports injury case-control studies. Major design goals for case-control studies include the accounting for prior injury risk exposure, and optimal definitions of both cases and suitable controls are needed to ensure this. This article reviews methodological aspects of published sports injury case-control studies, particularly with regard to the selection of controls. It argues for a new approach towards selecting controls for case-control studies that draws on an interface between epidemiological and biomechanical concepts. A review was conducted to identify sport injury case-control studies published in the peer-review literature during 1985-2008. Overall, 32 articles were identified, of which the majority related to upper or lower extremity injuries. Matching considerations were used for control selection in 16 studies. Specific mention of application of biomechanical principles in the selection of appropriate controls was absent from all studies, including those purporting to evaluate the benefits of personal protective equipment to protect against impact injury. This is a problem because it could lead to biased conclusions, as cases and controls are not fully comparable in terms of similar biomechanical impact profiles relating to the injury incident, such as site of the impact on the body. The strength of the conclusions drawn from case-control studies, and the extent to which results can be generalized, is directly influenced by the definition and recruitment of cases and appropriate controls. Future studies should consider the interface between epidemiological and biomechanical concepts when choosing appropriate controls to ensure that proper adjustment of prior exposure to injury risk is made. To provide necessary guidance for the optimal selection of controls in case-control studies of interventions to prevent sports-related impact injury, this review outlines a new case-control selection strategy that reflects the importance of biomechanical considerations, which ensures that controls are selected based on the presence of the same global injury mechanism as the cases. To summarize, the general biomechanical principles that should apply to the selection of controls in future case-control studies are as follows: (i) each control must have been exposed to the same global injury mechanism as the case, (e.g. head impact, fall onto outstretched arm); and (ii) intrinsic (individual) factors (e.g. age, sex, skill level) that might modify the person's response to the relevant biomechanical loads are adjusted when either selecting the controls or are in the analysis phase. The same considerations for control selection apply to other study designs such as matched cohort studies or case-crossover studies.

Flooding and emergency room visits for gastrointestinal illness in Massachusetts: a case-crossover study.

PubMed

Wade, Timothy J; Lin, Cynthia J; Jagai, Jyotsna S; Hilborn, Elizabeth D

2014-01-01

Floods and other severe weather events are anticipated to increase as a result of global climate change. Floods can lead to outbreaks of gastroenteritis and other infectious diseases due to disruption of sewage and water infrastructure and impacts on sanitation and hygiene. Floods have also been indirectly associated with outbreaks through population displacement and crowding. We conducted a case-crossover study to investigate the association between flooding and emergency room visits for gastrointestinal illness (ER-GI) in Massachusetts for the years 2003 through 2007. We obtained ER-GI visits from the State of Massachusetts and records of floods from the National Oceanic and Atmospheric Association's Storm Events Database. ER-GI visits were considered exposed if a flood occurred in the town of residence within three hazard periods of the visit: 0-4 days; 5-9 days; and 10-14 days. A time-stratified bi-directional design was used for control selection, matching on day of the week with two weeks lead or lag time from the ER-GI visit. Fixed effect logistic regression models were used to estimate the risk of ER-GI visits following the flood. A total of 270,457 ER-GI visits and 129 floods occurred in Massachusetts over the study period. Across all counties, flooding was associated with an increased risk for ER-GI in the 0-4 day period after flooding (Odds Ratio: 1.08; 95% Confidence Interval: 1.03-1.12); but not the 5-9 days (Odds Ratio: 0.995; 95% Confidence Interval: 0.955-1.04) or the 10-14 days after (Odds Ratio: 0.966, 95% Confidence Interval: 0.927-1.01). Similar results were observed for different definitions of ER-GI. The effect differed across counties, suggesting local differences in the risk and impact of flooding. Statewide, across the study period, an estimated 7% of ER-GI visits in the 0-4 days after a flood event were attributable to flooding.

Deep brain stimulation for treatment-resistant major depressive disorder: a comparison of two targets and long-term follow-up

PubMed Central

Raymaekers, S; Luyten, L; Bervoets, C; Gabriëls, L; Nuttin, B

2017-01-01

We previously found that electrical stimulation in the anterior limb of the internal capsule/bed nucleus of the stria terminalis (IC/BST) alleviates depressive symptoms in severe treatment-resistant obsessive-compulsive disorder (OCD) patients. Here we tested the hypothesis that electrical stimulation in either IC/BST or in the inferior thalamic peduncle (ITP) effectively reduces depressive symptoms in treatment-resistant major depressive disorder (TRD). In a double-blind crossover design, the effects of electrical stimulation at both targets were compared in TRD patients. The 17-item Hamilton Depression Rating scale (HAM-D) was the primary outcome measure. During the first crossover, patients received IC/BST stimulation versus no stimulation in random order (2 × 1 weeks). During the second crossover (3 × 2 months), patients received IC/BST versus ITP versus no stimulation. Patients and evaluators were blinded for stimulation conditions. All patients (n=7) were followed up for at least 3 years (3–8 years) after implantation. Six patients completed the first crossover and five patients completed the second. During the first crossover, mean (s.d.) HAM-D scores were 21.5 (2.7) for no stimulation and 11.5 (8.8) for IC/BST stimulation. During the second crossover, HAM-D scores were 15.4 (7.5) for no stimulation, 7.6 (3.8) for IC/BST stimulation and 11.2 (7.5) for ITP stimulation. The final sample size was too small to statistically analyze this second crossover. At last follow-up, only one patient preferred ITP over IC/BST stimulation. Two patients, with a history of suicide attempts before implantation, committed suicide during the follow-up phases of this study. Our data indicate that, in the long term, both ITP and IC/BST stimulation may alleviate depressive symptoms in patients suffering from TRD. PMID:29087373

Deep brain stimulation for treatment-resistant major depressive disorder: a comparison of two targets and long-term follow-up.

PubMed

Raymaekers, S; Luyten, L; Bervoets, C; Gabriëls, L; Nuttin, B

2017-10-31

We previously found that electrical stimulation in the anterior limb of the internal capsule/bed nucleus of the stria terminalis (IC/BST) alleviates depressive symptoms in severe treatment-resistant obsessive-compulsive disorder (OCD) patients. Here we tested the hypothesis that electrical stimulation in either IC/BST or in the inferior thalamic peduncle (ITP) effectively reduces depressive symptoms in treatment-resistant major depressive disorder (TRD). In a double-blind crossover design, the effects of electrical stimulation at both targets were compared in TRD patients. The 17-item Hamilton Depression Rating scale (HAM-D) was the primary outcome measure. During the first crossover, patients received IC/BST stimulation versus no stimulation in random order (2 × 1 weeks). During the second crossover (3 × 2 months), patients received IC/BST versus ITP versus no stimulation. Patients and evaluators were blinded for stimulation conditions. All patients (n=7) were followed up for at least 3 years (3-8 years) after implantation. Six patients completed the first crossover and five patients completed the second. During the first crossover, mean (s.d.) HAM-D scores were 21.5 (2.7) for no stimulation and 11.5 (8.8) for IC/BST stimulation. During the second crossover, HAM-D scores were 15.4 (7.5) for no stimulation, 7.6 (3.8) for IC/BST stimulation and 11.2 (7.5) for ITP stimulation. The final sample size was too small to statistically analyze this second crossover. At last follow-up, only one patient preferred ITP over IC/BST stimulation. Two patients, with a history of suicide attempts before implantation, committed suicide during the follow-up phases of this study. Our data indicate that, in the long term, both ITP and IC/BST stimulation may alleviate depressive symptoms in patients suffering from TRD.

Antipsychotic Use and Risk of Hospitalization or Death Due to Pneumonia in Persons With and Those Without Alzheimer Disease.

PubMed

Tolppanen, Anna-Maija; Koponen, Marjaana; Tanskanen, Antti; Lavikainen, Piia; Sund, Reijo; Tiihonen, Jari; Hartikainen, Sirpa; Taipale, Heidi

2016-12-01

The use of antipsychotic agents has been associated with increased pneumonia risk, but although people with dementia are particularly susceptible to pneumonia, only one small study has assessed the risk of pneumonia in relation to the use of antipsychotic agents among people with Alzheimer disease (AD). We investigated whether the incident use of antipsychotic agents, or specific antipsychotic agents, are related to a higher risk of hospitalization or death due to pneumonia in the Medication and Alzheimer Disease (MEDALZ) cohort. The cohort includes all individuals with AD who received a clinically verified AD diagnosis in Finland in 2005 to 2011 (N = 60,584; incident pneumonia, n = 12,225). A matched comparison cohort without AD (N = 60,584; incident pneumonia, n = 6,195) was used to compare the magnitude of risk. Results were adjusted for a propensity score derived from comorbidities, concomitant medications, and sociodemographic characteristics. Sensitivity analyses with case-crossover design were conducted. The use of antipsychotic agents was associated with a higher risk of pneumonia (adjusted hazard ratio [HR], 2.01; 95% CI, 1.90-2.13) in the AD cohort and a somewhat higher risk in the non-AD cohort (adjusted HR, 3.43; 95% CI, 2.99-3.93). Similar results were observed with case-crossover analyses (OR, 2.02; 95% CI, 1.75-2.34 in the AD cohort and OR, 2.59; 95% CI, 1.77-3.79 in the non-AD cohort). The three most commonly used antipsychotic agents (quetiapine, risperidone, haloperidol) had similar associations with pneumonia risk. Regardless of applied study design, treatment duration, or the choice of drug, the use of antipsychotic agents was associated with a higher risk of pneumonia. With observational data, we cannot fully rule out a shared causality between pneumonia and the use of antipsychotic agents, but the risk to benefit balance should be considered when antipsychotic agents are prescribed. Copyright © 2016 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.

An Ad-Hoc Adaptive Pilot Model for Pitch Axis Gross Acquisition Tasks

NASA Technical Reports Server (NTRS)

Hanson, Curtis E.

2012-01-01

An ad-hoc algorithm is presented for real-time adaptation of the well-known crossover pilot model and applied to pitch axis gross acquisition tasks in a generic fighter aircraft. Off-line tuning of the crossover model to human pilot data gathered in a fixed-based high fidelity simulation is first accomplished for a series of changes in aircraft dynamics to provide expected values for model parameters. It is shown that in most cases, for this application, the traditional crossover model can be reduced to a gain and a time delay. The ad-hoc adaptive pilot gain algorithm is shown to have desirable convergence properties for most types of changes in aircraft dynamics.

Design and numerical characterization of a crossover EBIS

NASA Astrophysics Data System (ADS)

Geyer, Sabrina; Langbein, A.; Meusel, Oliver; Kester, Oliver

2015-01-01

For the investigation of highly charged ions, a crossover EBIS (XEBIS) was developed at the University of Frankfurt. In contrast to conventional EBIS/T devices the compression of the electron beam is achieved by electrostatic focusing to a crossover point in the interaction region. This concept allows a compact and simple design. Simulations performed with EGUN show a perveance of 2.1×10-7 A/V3/2 for the realized gun system. In the interaction region the electron beam has a density of around 10 A/cm2 and a minimum radius of 0.15 mm. The XEBIS has a total length of 112 mm with a trap length of 26 mm. It is designed for electron beam energies of up to 6 keV/q. The storage capacity of the trap region is in the order of 1×108 charges. Charge state breeding studies with CBSIM indicate for the noble gases as maximal achievable charge state Ar16+, Kr30+ and Xe35+. Thus ion beam currents of around 2.04 nA assuming 50 Hz repetition rate can be expected. The emittance of the extracted beam is approximated to 8 mm mrad. After completion of the construction phase, the XEBIS will be installed for first performance investigations at a dedicated test bench, equipped with a fast Faraday Cup (FC), a retarding field spectrometer, a luminescence screen and optical diagnostics. Subsequently the XEBIS will serve as source for highly charged ions at different experimental setups.

Cluster randomised crossover trials with binary data and unbalanced cluster sizes: application to studies of near-universal interventions in intensive care.

PubMed

Forbes, Andrew B; Akram, Muhammad; Pilcher, David; Cooper, Jamie; Bellomo, Rinaldo

2015-02-01

Cluster randomised crossover trials have been utilised in recent years in the health and social sciences. Methods for analysis have been proposed; however, for binary outcomes, these have received little assessment of their appropriateness. In addition, methods for determination of sample size are currently limited to balanced cluster sizes both between clusters and between periods within clusters. This article aims to extend this work to unbalanced situations and to evaluate the properties of a variety of methods for analysis of binary data, with a particular focus on the setting of potential trials of near-universal interventions in intensive care to reduce in-hospital mortality. We derive a formula for sample size estimation for unbalanced cluster sizes, and apply it to the intensive care setting to demonstrate the utility of the cluster crossover design. We conduct a numerical simulation of the design in the intensive care setting and for more general configurations, and we assess the performance of three cluster summary estimators and an individual-data estimator based on binomial-identity-link regression. For settings similar to the intensive care scenario involving large cluster sizes and small intra-cluster correlations, the sample size formulae developed and analysis methods investigated are found to be appropriate, with the unweighted cluster summary method performing well relative to the more optimal but more complex inverse-variance weighted method. More generally, we find that the unweighted and cluster-size-weighted summary methods perform well, with the relative efficiency of each largely determined systematically from the study design parameters. Performance of individual-data regression is adequate with small cluster sizes but becomes inefficient for large, unbalanced cluster sizes. When outcome prevalences are 6% or less and the within-cluster-within-period correlation is 0.05 or larger, all methods display sub-nominal confidence interval coverage, with the less prevalent the outcome the worse the coverage. As with all simulation studies, conclusions are limited to the configurations studied. We confined attention to detecting intervention effects on an absolute risk scale using marginal models and did not explore properties of binary random effects models. Cluster crossover designs with binary outcomes can be analysed using simple cluster summary methods, and sample size in unbalanced cluster size settings can be determined using relatively straightforward formulae. However, caution needs to be applied in situations with low prevalence outcomes and moderate to high intra-cluster correlations. © The Author(s) 2014.

Comparison of the inhibitory effects of cilostazol, acetylsalicylic acid and ticlopidine on platelet functions ex vivo. Randomized, double-blind cross-over study.

PubMed

Ikeda, Y; Kikuchi, M; Murakami, H; Satoh, K; Murata, M; Watanabe, K; Ando, Y

1987-05-01

A randomized double-blind cross-over study was conducted to determine the inhibitory effects of acetylsalicylic acid (ASA), ticlopidine (TP) and cilostazol (OPC-13013; in the following briefly called CS), a new antithrombotic agent on platelet functions ex vivo. Nine patients with cerebral thrombosis were enrolled in this study. Patients were given each of the three drugs for one week in a complete cross-over design according to a randomization schedule, followed by a wash-out period with a placebo for one week. It was found that CS and TP significantly inhibited platelet aggregation induced by ADP. Collagen- and arachidonic acid-induced platelet aggregation was all inhibited by CS, TP and ASA. Duncan's multiple range test to compare the anti-platelet effects of the three drugs revealed that: CS greater than ASA and TP greater than ASA in inhibiting ADP-induced platelet aggregation and CS greater than TP and ASA greater than TP in inhibiting arachidonic acid-induced platelet aggregation. These results may suggest that CS is superior to ASA and TP in inhibiting platelet aggregation ex vivo.

Situational and contextual factors that increase the risk of harm when students drink: case-control and case-crossover investigation.

PubMed

Connor, Jennie; Cousins, Kimberly; Samaranayaka, Ari; Kypri, Kypros

2014-07-01

Better understanding of the circumstances of alcohol-related adverse events experienced by university students could identify opportunities for prevention. We aimed to identify situational and contextual factors associated with unintentional injury, assault, unsafe sex, sexual assault and drink-driving/riding amongst university students. We conducted a Web-based survey of full-time students aged 17-25 years at five New Zealand universities (n = 2683) and carried out between- and within-subjects comparisons (case-control and case-crossover, respectively) of situational and contextual characteristics of events in the last seven days and control drinking occasions. The response fraction was 49%. For the seven days preceding the survey, 4.9% of women and 7.4% of men reported at least one of the defined events while they were drinking or soon after. The number of drinking locations and getting drunker than expected were strongly associated with risk of an event in both case-control and case-crossover models, independent of consumption. Total number of drinks, drinking later and into the morning, and drinking with close friends were also associated with increased risk in the case-control analysis. No gender difference was seen after controlling for drinking and contextual factors. Strategies to reduce the duration and volume of alcohol consumption, including earlier closing of licensed premises, should be considered as countermeasures for alcohol-related adverse events. The use of two different comparison groups for the circumstances of adverse events when drinking can strengthen inferences about the contribution of contextual factors. © 2014 Australasian Professional Society on Alcohol and other Drugs.

Treatment of cystic cavities in X-linked juvenile retinoschisis: The first sequential cross-over treatment regimen with dorzolamide.

PubMed

Coussa, Razek Georges; Kapusta, Michael Alton

2017-12-01

To report the first sequential cross-over treatment with the longest ophthalmic follow-up in a case of X-linked juvenile retinoschisis (XLRS) successfully treated with topical dorzolamide. A healthy 34 year-old man presented with one month history of decreased visual acuity in his left eye. Funduscopy was significant for a blunted and cystoid-like foveal reflex in both eyes. The macular OCT showed cystic foveal changes OU. The patient was diagnosed with XLRS and was observed. On two subsequent follow-ups, a significant decrease in the patient's visual acuity warranted the use of topical dorzolamide for treating the cystic foveal changes, which completely resolved two months post-treatment initiation. Previous reports showed the benefit of dorzolamide in treating foveal cystic cavities in XLRS. To our knowledge, this is the first case of XLRS demonstrating the benefits of topical dorzolamide based on a sequential cross-over treatment regimen. It may also represent a case with the longest ophthalmic follow-up providing, in consequence, long-term understanding of the natural history and complications of this rare disease After ruling out major causes of cystoid macular edema, XLRS patients presenting with worsening of their visual acuities due to larger cystic macular changes may benefit from an alternating ON/OFF regimen of topical dorzolamide, which offers a significant treatment advantage outweighing its well-known side effects. Our study consolidates the importance of "medication vacation" by showing its efficacy in providing anatomical and visual functional improvements in patients with chronic cystic macular changes.

CONTROL FOR SEASONAL VARIATION AND TIME TREND IN CASE-CROSSOVER STUDIES OF ACUTE EFFECTS OF ENVIRONMENTAL EXPOSURES. (R827353C004)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

The dynamic crossover in water does not require bulk water.

PubMed

Turton, David A; Corsaro, Carmelo; Martin, David F; Mallamace, Francesco; Wynne, Klaas

2012-06-14

Many of the anomalous properties of water may be explained by invoking a second critical point that terminates the coexistence line between the low- and high-density amorphous states in the liquid. Direct experimental evidence of this point, and the associated polyamorphic liquid-liquid transition, is elusive as it is necessary for liquid water to be cooled below its homogeneous-nucleation temperature. To avoid crystallization, water in the eutectic LiCl solution has been studied but then it is generally considered that "bulk" water cannot be present. However, recent computational and experimental studies observe cooperative hydration in which case it is possible that sufficient hydrogen-bonded water is present for the essential characteristics of water to be preserved. For femtosecond optical Kerr-effect and nuclear magnetic resonance measurements, we observe in each case a fractional Stokes-Einstein relation with evidence of the dynamic crossover appearing near 220 K and 250 K respectively. Spectra obtained in the glass state also confirm the complex nature of the hydrogen-bonding modes reported for neat room-temperature water and support predictions of anomalous diffusion due to "worm-hole" structure.

Crossover assessment of cardiolocomotor synchronization during running.

PubMed

Cerqueira, Lucenildo Silva; D'Affonsêca Netto, Aluizio; Mello, Roger Gomes Tavares; Nadal, Jurandir

2017-02-01

This study aimed at testing the hypothesis that positive cardiolocomotor coordination (CLC) measure occurs by chance during a running task where the heart rate (HR) is approximated to the step frequency (StepF). The electrocardiogram and electromyogram from the right gastrocnemius lateralis muscle were continuously recorded from ten healthy young men running at a paced rhythm of 152 step/min, to monitor HR and StepF. CLC was evaluated by phase synchrograms and the index of conditional probability (iCP). Results were validated with surrogate data and a crossover approach, where the HR of one subject was related to the StepF of another one, and comparisons were made combining subjects two by two. Six subjects showed synchrogram structures and high iCP values (≥0.8), suggesting the occurrence of physiological entrainment, when the HR reached the SF range. In crossover analysis, phase synchrograms and iCP presented similar behavior of original data when the HR from one subject was close enough to the SF from another one. Significant iCP values in 46 of 90 comparisons (51%) were observed, including all cases crossing signals among the six positive cases. Synchrogram and iCP tools currently employed for measuring CLC are not appropriate because they indicate the occurrence of this phenomenon even among subjects who ran on different days and times of each other.

Hysteretic Four-Step Spin Crossover within a Three-Dimensional Porous Hofmann-like Material

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clements, John E.; Price, Jason R.; Neville, Suzanne M.

Materials that display multiple stepped spin crossover (SCO) transitions with accompanying hysteresis present the opportunity for ternary, quaternary, and quinary electronic switching and data storage but are rare in existence. Herein, we present the first report of a four-step hysteretic SCO framework. Single-crystal structure analysis of a porous 3D Hofmann-like material showed long-range ordering of spin states: HS, HS 0.67LS 0.33, HS 0.5LS 0.5, HS 0.33LS 0.67, and LS. These detailed structural studies provide insight into how multistep SCO materials can be rationally designed through control of host–host and host–guest interactions.

How job and family demands impact change in perceived stress: A dyadic study.

PubMed

Smoktunowicz, Ewelina; Cieślak, Roman

2018-01-07

The aim of this two-wave study has been to test the spillover and crossover of job and family demands on changes in perceived stress at work and in the family. Specifically, we proposed that demands from one domain (work or family) spilled over to another domain through interrrole conflict (work-family/family-work conflict) and context-specific self-efficacy. Additionally, we hypothesized that changes in perceived stress were impacted not only by a person's own demands through interrole conflict but also by the demands of one's significant other, in the process of crossover. The study was of dyadic design and it was conducted online, among 130 heterosexual couples, at 2 time points separated by 3 months interval. Hypotheses were verified by means of the path analysis. No support was found for the spillover of job and family demands on changes in perceived stress through interrole conflict and self-efficacy, neither for women nor for men. With regard to the crossover, no support was found for the actor effects, i.e., a person's demands did not impact changes in one's own work- and family-related perceived stress but partial support was found for the partner effects, i.e., women's job demands were associated with men's changes in work and family-related stress through women's work-family conflict, and men's family demands were associated with women's change in family-related perceived stress through men's family-work conflict. The study is a longitudinal test of the Spillover-Crossover model and Work-Home Resources model demonstrating that job and family demands are transmitted across domains and across partners in the intimate relationships through the interrole conflict but the nature of this crossover is different for men and women. Int J Occup Med Environ Health 2018;31(2)199-215. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

A Bayesian approach to the statistical analysis of device preference studies.

PubMed

Fu, Haoda; Qu, Yongming; Zhu, Baojin; Huster, William

2012-01-01

Drug delivery devices are required to have excellent technical specifications to deliver drugs accurately, and in addition, the devices should provide a satisfactory experience to patients because this can have a direct effect on drug compliance. To compare patients' experience with two devices, cross-over studies with patient-reported outcomes (PRO) as response variables are often used. Because of the strength of cross-over designs, each subject can directly compare the two devices by using the PRO variables, and variables indicating preference (preferring A, preferring B, or no preference) can be easily derived. Traditionally, methods based on frequentist statistics can be used to analyze such preference data, but there are some limitations for the frequentist methods. Recently, Bayesian methods are considered an acceptable method by the US Food and Drug Administration to design and analyze device studies. In this paper, we propose a Bayesian statistical method to analyze the data from preference trials. We demonstrate that the new Bayesian estimator enjoys some optimal properties versus the frequentist estimator. Copyright © 2012 John Wiley & Sons, Ltd.

Antibiotic rotation strategies to reduce antimicrobial resistance in Gram-negative bacteria in European intensive care units: study protocol for a cluster-randomized crossover controlled trial.

PubMed

van Duijn, Pleun J; Bonten, Marc J M

2014-07-10

Intensive care units (ICU) are epicenters for the emergence of antibiotic-resistant Gram-negative bacteria (ARGNB) because of high rates of antibiotic usage, rapid patient turnover, immunological susceptibility of acutely ill patients, and frequent contact between healthcare workers and patients, facilitating cross-transmission.Antibiotic stewardship programs are considered important to reduce antibiotic resistance, but the effectiveness of strategies such as, for instance, antibiotic rotation, have not been determined rigorously. Interpretation of available studies on antibiotic rotation is hampered by heterogeneity in implemented strategies and suboptimal study designs. In this cluster-randomized, crossover trial the effects of two antibiotic rotation strategies, antibiotic mixing and cycling, on the prevalence of ARGNB in ICUs are determined. Antibiotic mixing aims to create maximum antibiotic heterogeneity, and cycling aims to create maximum antibiotic homogeneity during consecutive periods. This is an open cluster-randomized crossover study of mixing and cycling of antibiotics in eight ICUs in five European countries. During cycling (9 months) third- or fourth-generation cephalosporins, piperacillin-tazobactam and carbapenems will be rotated during consecutive 6-week periods as the primary empiric treatment in patients suspected of infection caused by Gram-negative bacteria. During mixing (9 months), the same antibiotics will be rotated for each consecutive antibiotic course. Both intervention periods will be preceded by a baseline period of 4 months. ICUs will be randomized to consecutively implement either the mixing and then cycling strategy, or vice versa. The primary outcome is the ICU prevalence of ARGNB, determined through monthly point-prevalence screening of oropharynx and perineum. Secondary outcomes are rates of acquisition of ARGNB, bacteremia and appropriateness of therapy, length of stay in the ICU and ICU mortality. Results will be adjusted for intracluster correlation, and patient- and ICU-level variables of case-mix and infection-prevention measures using advanced regression modeling. This trial will determine the effects of antibiotic mixing and cycling on the unit-wide prevalence of ARGNB in ICUs. ClinicalTrials.gov NCT01293071 December 2010.

Scaling Laws for Shapes of Food Fragments by Human Mastication

NASA Astrophysics Data System (ADS)

Kobayashi, Naoki; Kohyama, Kaoru; Sasaki, Yo; Matsushita, Mitsugu

2007-04-01

Scaling property of the shape of fragments which were produced by masticating raw carrots has been studied experimentally and theoretically. Mastication experiments showed that most fragments have more or less isotropic shapes which are independent of the number of chewing strokes, whereas larger fragments than a crossover size have complicated shapes. Since the crossover size had the structure which was dependent on the number of chewing strokes, we have tried to propose dynamic scaling hypothesis analogous to the case of growing self-affine interface. It was found that the dynamic scaling yields fairly accurate values of the scaling exponents. Our results will provide a new observation and insight of not only sequential fragmentation but also construction for physiological measurement.

Effects of Risperidone on Cognitive-Motor Performance and Motor Movements in Chronically Medicated Children

ERIC Educational Resources Information Center

Aman, Michael G.; Hollway, Jill A.; Leone, Sarah; Masty, Jessica; Lindsay, Ronald; Nash, Patricia; Arnold, L. Eugene

2009-01-01

This study was designed to explore the placebo-controlled effects of risperidone on cognitive-motor processes, dyskinetic movements, and behavior in children receiving maintenance risperidone therapy. Sixteen children aged 4-14 years with disruptive behavior were randomly assigned to drug order in a crossover study of risperidone and placebo for 2…

Acute Exercise and Academic Achievement in High School Youth

ERIC Educational Resources Information Center

Harveson, Andrew; Hannon, James; Brusseau, Timothy; Podlog, Les; Chase, Ben; Kang, Kyoung-doo

2018-01-01

The purpose of this study was to compare the acute effects of Aerobic Exercise (AE), Resistance Exercise (RE), and a nonexercise (NE) control on measures of academic achievement (AA) and cognition in 10th grade males and females. This study utilized a randomized crossover design. Tenth grade males and females performed three exercise trials (AE,…

Dietary Protein and Calcium Interact to Influence Calcium Retention: A Controlled Feeding Study

USDA-ARS?s Scientific Manuscript database

Objective: To test the effect of dietary protein on Ca (Ca) retention at low and high Ca intakes. Methods: In a randomized, controlled feeding study with a 2x2 factorial crossover design, healthy post-menopausal women (n=27), consumed either ~675 or ~1510 mg Ca/d, with both low and high protein (pro...

Superconducting Vacuum-Gap Crossovers for High Performance Microwave Applications

NASA Technical Reports Server (NTRS)

Denis, Kevin L.; Brown, Ari D.; Chang, Meng-Ping; Hu, Ron; U-Yen, Kongpop; Wollack, Edward J.

2016-01-01

The design and fabrication of low-loss wide-bandwidth superconducting vacuum-gap crossovers for high performance millimeter wave applications are described. In order to reduce ohmic and parasitic losses at millimeter wavelengths a vacuum gap is preferred relative to dielectric spacer. Here, vacuum-gap crossovers were realized by using a sacrificial polymer layer followed by niobium sputter deposition optimized for coating coverage over an underlying niobium signal layer. Both coplanar waveguide and microstrip crossover topologies have been explored in detail. The resulting fabrication process is compatible with a bulk micro-machining process for realizing waveguide coupled detectors, which includes sacrificial wax bonding, and wafer backside deep reactive ion etching for creation of leg isolated silicon membrane structures. Release of the vacuum gap structures along with the wax bonded wafer after DRIE is implemented in the same process step used to complete the detector fabrication. ?

Development, preliminary usability and accuracy testing of the EBMT 'eGVHD App' to support GvHD assessment according to NIH criteria-a proof of concept.

PubMed

Schoemans, H; Goris, K; Durm, R V; Vanhoof, J; Wolff, D; Greinix, H; Pavletic, S; Lee, S J; Maertens, J; Geest, S D; Dobbels, F; Duarte, R F

2016-08-01

The EBMT Complications and Quality of Life Working Party has developed a computer-based algorithm, the 'eGVHD App', using a user-centered design process. Accuracy was tested using a quasi-experimental crossover design with four expert-reviewed case vignettes in a convenience sample of 28 clinical professionals. Perceived usefulness was evaluated by the technology acceptance model (TAM) and User satisfaction by the Post-Study System Usability Questionnaire (PSSUQ). User experience was positive, with a median of 6 TAM points (interquartile range: 1) and beneficial median total, and subscale PSSUQ scores. The initial standard practice assessment of the vignettes yielded 65% correct results for diagnosis and 45% for scoring. The 'eGVHD App' significantly increased diagnostic and scoring accuracy to 93% (+28%) and 88% (+43%), respectively (both P<0.05). The same trend was observed in the repeated analysis of case 2: accuracy improved by using the App (+31% for diagnosis and +39% for scoring), whereas performance tended to decrease once the App was taken away. The 'eGVHD App' could dramatically improve the quality of care and research as it increased the performance of the whole user group by about 30% at the first assessment and showed a trend for improvement of individual performance on repeated case evaluation.

Occurrence and extent of bruising according to duration of administration of subcutaneous low-molecular-weight heparin: a quasi-experimental case-crossover study.

PubMed

Palese, Alvisa; Aidone, Elena; Dante, Angelo; Pea, Federico

2013-01-01

Several authors have documented the role of low-molecular-weight heparin injection techniques in bruising. However, few researchers have measured the influence of injection duration on the occurrence and extent of bruising. The aim of this study was to evaluate the influence of different durations of subcutaneous heparin injection on the occurrence and extent of bruising. A quasi-experimental case-crossover study design was adopted in 2010. A consecutive series of patients admitted to 2 orthopedic units in a large (600 beds) teaching hospital located in northern Italy were eligible for enrolment. Injections were administered following a standard procedure. The manipulated variable was the duration of the injection, 10 seconds (treatment A) and 30 seconds (treatment B). The evaluation of bruise occurrence and extension performed after 48 hours and data analysis were conducted in a blinded fashion. A total of 150 patients receiving their first and second subcutaneous heparin injections (300 injections) were enrolled. Eighty-seven bruises were observed out of 300 injections (29%): 57 of 150 (38%) after injections lasting 10 seconds and 30 of 150 (20%) after injections lasting 30 seconds (relative risk, 1.50; 95% confidence interval, 1.21-1.86; P = .00). Of the 87 bruises that occurred, 69 (79.3%) were small (2-5 mm) and 18 (20.6%) were large (>5 mm), with no difference in size between 10- and 30-second injections (relative risk, 0.91; 95% confidence interval, 0.39-2.12; P = .83). Low-molecular-weight heparin injection should be administered over 30 seconds to decrease bruising. There is a need to reflect on the feasibility of such a practice because injecting low-molecular-weight heparin at 30 seconds requires accuracy, a steady hand, the absence of tremor, a calm environment, and the ability to administer an infinitesimally small amount of liquid (eg, 0.4 mL) per second.

Methodological considerations, such as directed acyclic graphs, for studying "acute on chronic" disease epidemiology: chronic obstructive pulmonary disease example.

PubMed

Tsai, Chu-Lin; Camargo, Carlos A

2009-09-01

Acute exacerbations of chronic disease are ubiquitous in clinical medicine, and thus far, there has been a paucity of integrated methodological discussion on this phenomenon. We use acute exacerbations of chronic obstructive pulmonary disease as an example to emphasize key epidemiological and statistical issues for this understudied field in clinical epidemiology. Directed acyclic graphs are a useful epidemiological tool to explain the differential effects of risk factor on health outcomes in studies of acute and chronic phases of disease. To study the pathogenesis of acute exacerbations of chronic disease, case-crossover design and time-series analysis are well-suited study designs to differentiate acute and chronic effect. Modeling changes over time and setting appropriate thresholds are important steps to separate acute from chronic phases of disease in serial measurements. In statistical analysis, acute exacerbations are recurrent events, and some individuals are more prone to recurrences than others. Therefore, appropriate statistical modeling should take into account intraindividual dependence. Finally, we recommend the use of "event-based" number needed to treat (NNT) to prevent a single exacerbation instead of traditional patient-based NNT. Addressing these methodological challenges will advance research quality in acute on chronic disease epidemiology.

Effects of acoustic deterrents on foraging bats

USGS Publications Warehouse

Johnson, Joshua B.; Ford, W. Mark; Rodrigue, Jane L.; Edwards, John W.

2012-01-01

Significant bat mortality events associated with wind energy expansion, particularly in the Appalachians, have highlighted the need for development of possible mitigation practices to reduce or prevent strike mortality. Other than increasing turbine cut-in speed, acoustic deterrents probably hold the greatest promise for reducing bat mortality. However, acoustic deterrent effectiveness and practicality has not been experimentally examined and is limited to site-specific case studies. Accordingly, we used a crossover experimental design with prior control period to show that bat activity was reduced 17.1 percent by the deployment of ultrasonic deterrents placed around gauged watershed weir ponds on the Fernow Experimental Forest in West Virginia. We caution that while our results should not be extrapolated to the scope of a typical wind energy production facility, the results warrant further research on the use of acoustic deterrents to reduce bat fatalities.

Predictors of post-partum damage accrual in systemic lupus erythematosus: data from LUMINA, a multiethnic US cohort (XXXVIII).

PubMed

Andrade, R M; McGwin, G; Alarcón, G S; Sanchez, M L; Bertoli, A M; Fernández, M; Fessler, B J; Apte, M; Arango, A M; Bastian, H M; Vilá, L M; Reveille, J D

2006-11-01

To determine the impact of pregnancy on systemic lupus erythematosus (SLE) outcome. SLE patients, age >or=16 yrs, disease duration

Registry-linked electronic influenza vaccine provider reminders: a cluster-crossover trial.

PubMed

Stockwell, Melissa S; Catallozzi, Marina; Camargo, Stewin; Ramakrishnan, Rajasekhar; Holleran, Stephen; Findley, Sally E; Kukafka, Rita; Hofstetter, Annika M; Fernandez, Nadira; Vawdrey, David K

2015-01-01

To determine the impact of a vaccination reminder in an electronic health record supplemented with data from an immunization information system (IIS). A noninterruptive influenza vaccination reminder, based on a real-time query of hospital and city IIS, was used at 4 urban, academically affiliated clinics serving a low-income population. Using a randomized cluster-crossover design, each study site had "on" and "off" period during the fall and winter of 2011-2012. Influenza vaccination during a clinic visit was assessed for 6-month to 17-year-old patients. To assess sustainability, the reminder was active at all sites during the 2012-2013 season. In the 2011-2012 season, 8481 unique non-up-to-date children had visits. Slightly more non-up-to-date children seen when the reminder was 'on' were vaccinated than when 'off' (76.2% vs 73.8%; P = .027). Effects were seen in the winter (67.9% vs 62.2%; P = .005), not fall (76.8% vs 76.5%). The reminder also increased documentation of the reason for vaccine non-administration (68.1% vs 41.5%; P < .0001). During the 2011-2012 season, the reminder displayed for 8630 unique visits, and clinicians interacted with it in 83.1% of cases where patients required vaccination. During the 2012-2013 season, it displayed for 22 248 unique visits; clinicians interacted with it in 84.8% of cases. An IIS-linked influenza vaccination reminder increased vaccination later in the winter when fewer vaccine doses are usually given. Although the reminder did not require clinicians to interact with it, they frequently did; utilization did not wane over time. Copyright © 2015 by the American Academy of Pediatrics.

[Association between ambient temperature and hospital emergency room visits for cardiovascular diseases: a case-crossover study].

PubMed

Guo, Yu-Ming; Wang, Jia-Jia; Li, Guo-Xing; Zheng, Ya-An; He, Wichmann; Pan, Xiao-Chuan

2009-08-01

To explore the association between ambient average temperature and hospital emergency room visits for cardiovascular diseases (International Classification of Diseases, Tenth Vision ICD-10: I00 - I99) in Beijing, China. Data was collected on daily hospital emergency room visits for cardiovascular diseases from Peking University Third Hospital, including meteorological data (daily average temperature, relative humidity, wind speed, and atmospheric pressure) from the China Meteorological Data Sharing Service System, and on air pollution from the Beijing Municipal Environmental Monitoring Center. Time-stratified case-crossover design was used to analyze data on 4 seasons. After adjusting data on air pollution, 1 degree ( degrees C) increase of ambient average temperature would associate with the emergency room visits of odds ratio (ORs) as 1.282 (95%CI: 1.250 - 1.315), 1.027 (95%CI: 1.001 - 1.055), 0.661 (95%CI: 0.637 - 0.687), and 0.960 (95%CI: 0.937 - 0.984) in spring, summer, autumn, and winter respectively. After controlling the influence of relative humidity, wind speed, and atmospheric pressure, 1 degrees C increase in the ambient average temperature would be associated with the emergency room visits on ORs value as 1.423 (95%CI: 1.377 - 1.471), 1.082 (95%CI: 1.041 - 1.124), 0.633 (95%CI: 0.607 - 0.660) and 0.971 (95%CI: 0.944 - 1.000) in spring, summer, autumn, and winter respectively. These data on outcomes suggested that the elevated level of ambient temperature would increase the hospital emergency room visits for cardiovascular diseases in spring and summer while the elevated level of ambient temperature would decrease the hospital emergency room visits for the cardiovascular diseases in autumn and winter, suggesting that patients with cardiovascular diseases should pay attention to the climate change.

Heat and risk of myocardial infarction: hourly level case-crossover analysis of MINAP database

PubMed Central

Armstrong, Ben; Hajat, Shakoor; Haines, Andy; Wilkinson, Paul; Smeeth, Liam

2012-01-01

Objective To quantify the association between exposure to higher temperatures and the risk of myocardial infarction at an hourly temporal resolution. Design Case-crossover study. Setting England and Wales Myocardial Ischaemia National Audit Project (MINAP) database. Participants 24 861 hospital admissions for myocardial infarction occurring in 11 conurbations during the warmest months (June to August) of the years 2003-09. Main outcome measure Odds ratio of myocardial infarction for a 1°C increase in temperature. Results Strong evidence was found for an effect of heat acting 1-6 hours after exposure to temperatures above an estimated threshold of 20°C (95% confidence interval 16°C to 25°C). For each 1°C increase in temperature above this threshold, the risk of myocardial infarction increased by 1.9% (0.5% to 3.3%, P=0.009). Later reductions in risk seemed to offset early increases in risk: the cumulative effect of a 1°C rise in temperature above the threshold was 0.2% (−2.1% to 2.5%) by the end of the third day after exposure. Conclusions Higher ambient temperatures above a threshold of 20°C seem to be associated with a transiently increased risk of myocardial infarction 1-6 hours after exposure. Reductions in risk at longer lags are consistent with heat triggering myocardial infarctions early in highly vulnerable people who would otherwise have had a myocardial infarction some time later (“short term displacement”). Policies aimed at reducing the health effects of hot weather should include consideration of effects operating at sub-daily timescales. PMID:23243290

How air pollution influences clinical management of respiratory diseases. A case-crossover study in Milan.

PubMed

Santus, Pierachille; Russo, Antonio; Madonini, Enzo; Allegra, Luigi; Blasi, Francesco; Centanni, Stefano; Miadonna, Antonio; Schiraldi, Gianfranco; Amaducci, Sandro

2012-10-18

Environmental pollution is a known risk factor for multiple diseases and furthermore increases rate of hospitalisations. We investigated the correlation between emergency room admissions (ERAs) of the general population for respiratory diseases and the environmental pollutant levels in Milan, a metropolis in northern Italy. We collected data from 45770 ERAs for respiratory diseases. A time-stratified case-crossover design was used to investigate the association between air pollution levels and ERAs for acute respiratory conditions. The effects of air pollutants were investigated at lag 0 to lag 5, lag 0-2 and lag 3-5 in both single and multi-pollutant models, adjusted for daily weather variables. An increase in ozone (O(3)) levels at lag 3-5 was associated with a 78% increase in the number of ERAs for asthma, especially during the warm season. Exposure to carbon monoxide (CO) proved to be a risk factor for pneumonia at lag 0-2 and in the warm season increased the risk of ERA by 66%. A significant association was found between ERAs for COPD exacerbation and levels of sulphur dioxide (SO(2)), CO, nitrate dioxide (NO(2)), and particulate matter (PM(10) and PM(2.5)). The multipollutant model that includes all pollutants showed a significant association between CO (26%) and ERA for upper respiratory tract diseases at lag 0-2. For chronic obstructive pulmonary disease (COPD) exacerbations, only CO (OR 1.19) showed a significant association. Exposure to environmental pollution, even at typical low levels, can increase the risk of ERA for acute respiratory diseases and exacerbation of obstructive lung diseases in the general population.

High-Performance Oligomeric Catholytes for Effective Macromolecular Separation in Nonaqueous Redox Flow Batteries

PubMed Central

2018-01-01

Nonaqueous redox flow batteries (NRFBs) represent an attractive technology for energy storage from intermittent renewable sources. In these batteries, electrical energy is stored in and extracted from electrolyte solutions of redox-active molecules (termed catholytes and anolytes) that are passed through an electrochemical flow cell. To avoid battery self-discharge, the anolyte and catholyte solutions must be separated by a membrane in the flow cell. This membrane prevents crossover of the redox active molecules, while simultaneously allowing facile transport of charge-balancing ions. A key unmet challenge for the field is the design of redox-active molecule/membrane pairs that enable effective electrolyte separation while maintaining optimal battery properties. Herein, we demonstrate the development of oligomeric catholytes based on tris(dialkylamino)cyclopropenium (CP) salts that are specifically tailored for pairing with size-exclusion membranes composed of polymers of intrinsic microporosity (PIMs). Systematic studies were conducted to evaluate the impact of oligomer size/structure on properties that are crucial for flow battery performance, including cycling stability, charge capacity, solubility, electron transfer kinetics, and crossover rates. These studies have led to the identification of a CP-derived tetramer in which these properties are all comparable, or significantly improved, relative to the monomeric counterpart. Finally, a proof-of-concept flow battery is demonstrated by pairing this tetrameric catholyte with a PIM membrane. After 6 days of cycling, no crossover is detected, demonstrating the promise of this approach. These studies provide a template for the future design of other redox-active oligomers for this application. PMID:29532018

High-Performance Oligomeric Catholytes for Effective Macromolecular Separation in Nonaqueous Redox Flow Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hendriks, Koen H.; Robinson, Sophia G.; Braten, Miles N.

Nonaqueous redox flow batteries (NRFBs) represent an attractive technology for energy storage from intermittent renewable sources. In these batteries, electrical energy is stored in and extracted from electrolyte solutions of redox-active molecules (termed catholytes and anolytes) that are passed through an electrochemical flow cell. To avoid battery self-discharge, the anolyte and catholyte solutions must be separated by a membrane in the flow cell. This membrane prevents crossover of the redox active molecules, while simultaneously allowing facile transport of charge-balancing ions. A key unmet challenge for the field is the design of redox-active molecule/membrane pairs that enable effective electrolyte separation whilemore » maintaining optimal battery properties. Herein, we demonstrate the development of oligomeric catholytes based on tris(dialkylamino)cyclopropenium (CP) salts that are specifically tailored for pairing with size-exclusion membranes composed of polymers of intrinsic microporosity (PIMs). Systematic studies were conducted to evaluate the impact of oligomer size/structure on properties that are crucial for flow battery performance, including cycling stability, charge capacity, solubility, electron transfer kinetics, and crossover rates. These studies have led to the identification of a CP-derived tetramer in which these properties are all comparable, or significantly improved, relative to the monomeric counterpart. Finally, a proof-of-concept flow battery is demonstrated by pairing this tetrameric catholyte with a PIM membrane. After 6 days of cycling, no crossover is detected, demonstrating the promise of this approach. Finally, these studies provide a template for the future design of other redox-active oligomers for this application.« less

High-Performance Oligomeric Catholytes for Effective Macromolecular Separation in Nonaqueous Redox Flow Batteries.

PubMed

Hendriks, Koen H; Robinson, Sophia G; Braten, Miles N; Sevov, Christo S; Helms, Brett A; Sigman, Matthew S; Minteer, Shelley D; Sanford, Melanie S

2018-02-28

Nonaqueous redox flow batteries (NRFBs) represent an attractive technology for energy storage from intermittent renewable sources. In these batteries, electrical energy is stored in and extracted from electrolyte solutions of redox-active molecules (termed catholytes and anolytes) that are passed through an electrochemical flow cell. To avoid battery self-discharge, the anolyte and catholyte solutions must be separated by a membrane in the flow cell. This membrane prevents crossover of the redox active molecules, while simultaneously allowing facile transport of charge-balancing ions. A key unmet challenge for the field is the design of redox-active molecule/membrane pairs that enable effective electrolyte separation while maintaining optimal battery properties. Herein, we demonstrate the development of oligomeric catholytes based on tris(dialkylamino)cyclopropenium (CP) salts that are specifically tailored for pairing with size-exclusion membranes composed of polymers of intrinsic microporosity (PIMs). Systematic studies were conducted to evaluate the impact of oligomer size/structure on properties that are crucial for flow battery performance, including cycling stability, charge capacity, solubility, electron transfer kinetics, and crossover rates. These studies have led to the identification of a CP-derived tetramer in which these properties are all comparable, or significantly improved, relative to the monomeric counterpart. Finally, a proof-of-concept flow battery is demonstrated by pairing this tetrameric catholyte with a PIM membrane. After 6 days of cycling, no crossover is detected, demonstrating the promise of this approach. These studies provide a template for the future design of other redox-active oligomers for this application.

High-Performance Oligomeric Catholytes for Effective Macromolecular Separation in Nonaqueous Redox Flow Batteries

DOE PAGES

Hendriks, Koen H.; Robinson, Sophia G.; Braten, Miles N.; ...

2018-01-17

Nonaqueous redox flow batteries (NRFBs) represent an attractive technology for energy storage from intermittent renewable sources. In these batteries, electrical energy is stored in and extracted from electrolyte solutions of redox-active molecules (termed catholytes and anolytes) that are passed through an electrochemical flow cell. To avoid battery self-discharge, the anolyte and catholyte solutions must be separated by a membrane in the flow cell. This membrane prevents crossover of the redox active molecules, while simultaneously allowing facile transport of charge-balancing ions. A key unmet challenge for the field is the design of redox-active molecule/membrane pairs that enable effective electrolyte separation whilemore » maintaining optimal battery properties. Herein, we demonstrate the development of oligomeric catholytes based on tris(dialkylamino)cyclopropenium (CP) salts that are specifically tailored for pairing with size-exclusion membranes composed of polymers of intrinsic microporosity (PIMs). Systematic studies were conducted to evaluate the impact of oligomer size/structure on properties that are crucial for flow battery performance, including cycling stability, charge capacity, solubility, electron transfer kinetics, and crossover rates. These studies have led to the identification of a CP-derived tetramer in which these properties are all comparable, or significantly improved, relative to the monomeric counterpart. Finally, a proof-of-concept flow battery is demonstrated by pairing this tetrameric catholyte with a PIM membrane. After 6 days of cycling, no crossover is detected, demonstrating the promise of this approach. Finally, these studies provide a template for the future design of other redox-active oligomers for this application.« less

Exercise training, vascular function, and functional capacity in middle-aged subjects.

PubMed

Maiorana, A; O'Driscoll, G; Dembo, L; Goodman, C; Taylor, R; Green, D

2001-12-01

The aim of this study was to investigate the effect of 8 wk of exercise training on functional capacity, muscular strength, body composition, and vascular function in sedentary but healthy subjects by using a randomized, crossover protocol. After familiarization sessions, 19 subjects aged 47 +/- 2 yr (mean +/- SE) undertook a randomized, crossover design study of the effect of 8 wk of supervised circuit training consisting of combined aerobic and resistance exercise. Peak oxygen uptake (.VO(2peak)), sum of 7 maximal voluntary contractions and the sum of 8 skinfolds and 5 segment girths were determined at entry, crossover, and 16 wk. Endothelium-dependent and -independent vascular function were determined by forearm strain-gauge plethysmography and intrabrachial infusions of acetylcholine (ACh) and sodium nitroprusside (SNP) in 16 subjects. Training did not alter ACh or SNP responses. .VO(2peak), (28.6 +/- 1.1 to 32.6 +/- 1.3 mL.kg(-1).min(-1), P < 0.001), exercise test duration (17.4 +/- 1.1 to 22.1 +/- 1.2 min, P < 0.001), and muscular strength (465 +/- 27 to 535 +/- 27 kg, P < 0.001) significantly increased after the exercise program, whereas skinfolds decreased (144 +/- 10 vs 134 +/- 9 mm, P < 0.001). These results suggest that moderate intensity circuit training designed to minimize the involvement of the arms improves functional capacity, body composition, and strength in healthy, middle-aged subjects without significantly influencing upper limb vascular function. This finding contrasts with previous studies in subjects with type 2 diabetes and heart failure that employed an identical training program.

Macromolecular Design Strategies for Preventing Active-Material Crossover in Non-Aqueous All-Organic Redox-Flow Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Doris, Sean E.; Ward, Ashleigh L.; Baskin, Artem

Intermittent energy sources, including solar and wind, require scalable, low-cost, multi-hour energy storage solutions in order to be effectively incorporated into the grid. All-Organic non-aqueous redox-flow batteries offer a solution, but suffer from rapid capacity fade and low Coulombic efficiency due to the high permeability of redox-active species across the battery's membrane. In this paper, we show that active-species crossover is arrested by scaling the membrane's pore size to molecular dimensions and in turn increasing the size of the active material above the membrane's pore-size exclusion limit. When oligomeric redox-active organics (RAOs) were paired with microporous polymer membranes, the ratemore » of active-material crossover was reduced more than 9000-fold compared to traditional separators at minimal cost to ionic conductivity. This corresponds to an absolute rate of RAO crossover of less than 3 μmol cm -2 day -1 (for a 1.0 m concentration gradient), which exceeds performance targets recently set forth by the battery industry. Finally, this strategy was generalizable to both high and low-potential RAOs in a variety of non-aqueous electrolytes, highlighting the versatility of macromolecular design in implementing next-generation redox-flow batteries.« less

Macromolecular Design Strategies for Preventing Active-Material Crossover in Non-Aqueous All-Organic Redox-Flow Batteries.

PubMed

Doris, Sean E; Ward, Ashleigh L; Baskin, Artem; Frischmann, Peter D; Gavvalapalli, Nagarjuna; Chénard, Etienne; Sevov, Christo S; Prendergast, David; Moore, Jeffrey S; Helms, Brett A

2017-02-01

Intermittent energy sources, including solar and wind, require scalable, low-cost, multi-hour energy storage solutions in order to be effectively incorporated into the grid. All-Organic non-aqueous redox-flow batteries offer a solution, but suffer from rapid capacity fade and low Coulombic efficiency due to the high permeability of redox-active species across the battery's membrane. Here we show that active-species crossover is arrested by scaling the membrane's pore size to molecular dimensions and in turn increasing the size of the active material above the membrane's pore-size exclusion limit. When oligomeric redox-active organics (RAOs) were paired with microporous polymer membranes, the rate of active-material crossover was reduced more than 9000-fold compared to traditional separators at minimal cost to ionic conductivity. This corresponds to an absolute rate of RAO crossover of less than 3 μmol cm -2  day -1 (for a 1.0 m concentration gradient), which exceeds performance targets recently set forth by the battery industry. This strategy was generalizable to both high and low-potential RAOs in a variety of non-aqueous electrolytes, highlighting the versatility of macromolecular design in implementing next-generation redox-flow batteries. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Macromolecular Design Strategies for Preventing Active-Material Crossover in Non-Aqueous All-Organic Redox-Flow Batteries

DOE PAGES

Doris, Sean E.; Ward, Ashleigh L.; Baskin, Artem; ...

2017-01-10

Intermittent energy sources, including solar and wind, require scalable, low-cost, multi-hour energy storage solutions in order to be effectively incorporated into the grid. All-Organic non-aqueous redox-flow batteries offer a solution, but suffer from rapid capacity fade and low Coulombic efficiency due to the high permeability of redox-active species across the battery's membrane. In this paper, we show that active-species crossover is arrested by scaling the membrane's pore size to molecular dimensions and in turn increasing the size of the active material above the membrane's pore-size exclusion limit. When oligomeric redox-active organics (RAOs) were paired with microporous polymer membranes, the ratemore » of active-material crossover was reduced more than 9000-fold compared to traditional separators at minimal cost to ionic conductivity. This corresponds to an absolute rate of RAO crossover of less than 3 μmol cm -2 day -1 (for a 1.0 m concentration gradient), which exceeds performance targets recently set forth by the battery industry. Finally, this strategy was generalizable to both high and low-potential RAOs in a variety of non-aqueous electrolytes, highlighting the versatility of macromolecular design in implementing next-generation redox-flow batteries.« less

Unique Study Designs in Nephrology: N-of-1 Trials and Other Designs.

PubMed

Samuel, Joyce P; Bell, Cynthia S

2016-11-01

Alternatives to the traditional parallel-group trial design may be required to answer clinical questions in special populations, rare conditions, or with limited resources. N-of-1 trials are a unique trial design which can inform personalized evidence-based decisions for the patient when data from traditional clinical trials are lacking or not generalizable. A concise overview of factorial design, cluster randomization, adaptive designs, crossover studies, and n-of-1 trials will be provided along with pertinent examples in nephrology. The indication for analysis strategies such as equivalence and noninferiority trials will be discussed, as well as analytic pitfalls. Copyright © 2016 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

Crossover between the Gaussian orthogonal ensemble, the Gaussian unitary ensemble, and Poissonian statistics.

PubMed

Schweiner, Frank; Laturner, Jeanine; Main, Jörg; Wunner, Günter

2017-11-01

Until now only for specific crossovers between Poissonian statistics (P), the statistics of a Gaussian orthogonal ensemble (GOE), or the statistics of a Gaussian unitary ensemble (GUE) have analytical formulas for the level spacing distribution function been derived within random matrix theory. We investigate arbitrary crossovers in the triangle between all three statistics. To this aim we propose an according formula for the level spacing distribution function depending on two parameters. Comparing the behavior of our formula for the special cases of P→GUE, P→GOE, and GOE→GUE with the results from random matrix theory, we prove that these crossovers are described reasonably. Recent investigations by F. Schweiner et al. [Phys. Rev. E 95, 062205 (2017)2470-004510.1103/PhysRevE.95.062205] have shown that the Hamiltonian of magnetoexcitons in cubic semiconductors can exhibit all three statistics in dependence on the system parameters. Evaluating the numerical results for magnetoexcitons in dependence on the excitation energy and on a parameter connected with the cubic valence band structure and comparing the results with the formula proposed allows us to distinguish between regular and chaotic behavior as well as between existent or broken antiunitary symmetries. Increasing one of the two parameters, transitions between different crossovers, e.g., from the P→GOE to the P→GUE crossover, are observed and discussed.

Work-related psychosocial events as triggers of sick leave - results from a Swedish case-crossover study

PubMed Central

2011-01-01

Background Although illness is an important cause of sick leave, it has also been suggested that non-medical risk factors may influence this association. If such factors impact on the period of decision making, they should be considered as triggers. Yet, there is no empirical support available. The aim was to investigate whether recent exposure to work-related psychosocial events can trigger the decision to report sick when ill. Methods A case-crossover design was applied to 546 sick-leave spells, extracted from a Swedish cohort of 1 430 employees with a 3-12 month follow-up of new sick-leave spells. Exposure in a case period corresponding to an induction period of one or two days was compared with exposure during control periods sampled from workdays during a two-week period prior to sick leave for the same individual. This was done according to the matched-pair interval and the usual frequency approaches. Results are presented as odds ratios (OR) with 95% confidence intervals (CI). Results Most sick-leave spells happened in relation to acute, minor illnesses that substantially reduced work ability. The risk of taking sick leave was increased when individuals had recently been exposed to problems in their relationship with a superior (OR 3.63; CI 1.44-9.14) or colleagues (OR 4.68; CI 1.43-15.29). Individuals were also more inclined to report sick on days when they expected a very stressful work situation than on a day when they were not under such stress (OR 2.27; CI 1.40-3.70). Conclusions Exposure to problems in workplace relationships or a stressful work situation seems to be able to trigger reporting sick. Psychosocial work-environmental factors appear to have a short-term effect on individuals when deciding to report sick. PMID:21429193

Short-term nighttime wind turbine noise and cardiovascular events: A nationwide case-crossover study from Denmark.

PubMed

Poulsen, Aslak Harbo; Raaschou-Nielsen, Ole; Peña, Alfredo; Hahmann, Andrea N; Nordsborg, Rikke Baastrup; Ketzel, Matthias; Brandt, Jørgen; Sørensen, Mette

2018-05-01

The number of people exposed to wind turbine noise (WTN) is increasing. WTN is reported as more annoying than traffic noise at similar levels. Long-term exposure to traffic noise has consistently been associated with cardiovascular disease, whereas effects of short-term exposure are much less investigated due to little day-to-day variation of e.g. road traffic noise. WTN varies considerably due to changing weather conditions allowing investigation of short-term effects of WTN on cardiovascular events. We identified all hospitalisations and deaths from stroke (16,913 cases) and myocardial infarction (MI) (17,559 cases) among Danes exposed to WTN between 1982 and 2013. We applied a time-stratified, case-crossover design. Using detailed data on wind turbine type and hourly wind data at each wind turbine, we simulated mean nighttime outdoor (10-10,000 Hz) and nighttime low frequency (LF) indoor WTN (10-160 Hz) over the 4 days preceding diagnosis and reference days. For indoor LF WTN between 10 and 15 dB(A) and above 15 dB(A), odds ratios (ORs) for MI were 1.27 (95% confidence interval (CI): 0.97-1.67; cases = 198) and 1.62 (95% CI: 0.76-3.45; cases = 21), respectively, when compared to indoor LF WTN below 5 dB(A). For stroke, corresponding ORs were 1.17 (95% CI: 0.95-1.69; cases = 166) and 2.30 (95% CI: 0.96-5.50; cases = 15). The elevated ORs above 15 dB(A) persisted across sensitivity analyses. When looking at specific lag times, noise exposure one day before MI events and three days before stroke events were associated with the highest ORs. For outdoor WTN at night, we observed both increased and decreased risk estimates. This study did not provide conclusive evidence of an association between WTN and MI or stroke. It does however suggest that indoor LF WTN at night may trigger cardiovascular events, whereas these events seemed largely unaffected by nighttime outdoor WTN. These findings need reproduction, as they were based on few cases and may be due to chance. Copyright © 2018 Elsevier Ltd. All rights reserved.

A Crossover Design for Comparative Efficacy: A 36-Week Randomized Trial of Bevacizumab and Ranibizumab for Diabetic Macular Edema.

PubMed

Wiley, Henry E; Thompson, Darby J S; Bailey, Clare; Chew, Emily Y; Cukras, Catherine A; Jaffe, Glenn J; Lee, Richard W J; Loken, Erin K; Meyerle, Catherine B; Wong, Wai; Ferris, Frederick L

2016-04-01

To investigate the comparative efficacy of bevacizumab (Avastin) and ranibizumab (Lucentis; both Genentech, Inc, South San Francisco, CA) for diabetic macular edema (DME) using a crossover study design. Randomized, double-masked, 36-week, 3-period crossover clinical trial. Fifty-six subjects with DME involving the center of the macula in one or both eyes. Monthly intravitreous injections of bevacizumab (1.25 mg) or ranibizumab (0.3 mg). Comparison of mean changes in visual acuity and central retinal thickness, tested using a linear mixed-effects model. Based on the linear mixed-effects model, the 3-month estimated mean improvement in visual acuity was 5.3 letters for bevacizumab and 6.6 letters for ranibizumab (difference, 1.3 letters; P = 0.039). Estimated change in optical coherence tomography (OCT) central subfield mean thickness (CSMT) was -89 μm for bevacizumab and -137 μm for ranibizumab (difference, 48 μm; P < 0.001). Incorporating cumulative treatment benefit, the model yielded a predicted 36-week (9-month) average improvement in visual acuity of 7.1 letters (95% confidence interval [CI], 5.0-9.2) for bevacizumab and 8.4 letters (95% CI, 6.3-10.5) for ranibizumab, and a change in OCT CSMT of -128 μm (95% CI, -155 to -100) for bevacizumab and -176 μm (95% CI, -202 to -149) for ranibizumab. There was no significant treatment-by-period interaction (i.e., treatment difference was constant in all 3 periods), nor was there a significant differential carryover effect from one period to the next. This trial demonstrated a statistically significant but small relative clinical benefit of ranibizumab compared with bevacizumab for treatment of DME, using a markedly reduced sample size relative to a full comparative efficacy study. The effects on visual acuity and central retinal thickness for the 2 drugs are consistent with those reported at 1 year for the concurrent parallel-group trial by the Diabetic Retinopathy Clinical Research Network testing bevacizumab, ranibizumab, and aflibercept for DME. The 3-period crossover design allowed for meaningful and efficient comparison, suggesting that this approach may be useful for future comparative efficacy studies of anti-vascular endothelial growth factor drugs for DME. Published by Elsevier Inc.

Melatonin improves sleep in children with epilepsy: randomized, double-blind cross-over study

PubMed Central

Jain, Sejal V; Horn, Paul S; Simakajornboon, Narong; Beebe, Dean W; Holland, Katherine; Byars, Anna W; Glauser, Tracy A

2015-01-01

Objective Insomnia, especially maintenance insomnia is widely prevalent in epilepsy. Although melatonin is commonly used, limited data address its efficacy. We performed a randomized, double-blind, placebo-controlled, cross-over study to identify the effects of melatonin on sleep and seizure control in children with epilepsy. Methods Eleven pre-pubertal, developmentally normal children aged 6–11 years with epilepsy were randomized by software algorithm to receive placebo or 9 mg sustained release melatonin for 4 weeks, followed by a 1-week washout and 4-week crossover condition. The pharmacy performed blinding; patients, parents and study staff other than a statistician were blinded. Primary outcomes were sleep onset latency and wakefulness after sleep onset (WASO) measured on polysomnography. Secondary outcomes included seizure frequency, epileptiform spike density per hour of sleep on EEG and reaction time measures on psychomotor vigilance task. Statistical tests appropriate for cross-over designs were used for analysis. Results Data were analyzed from ten subjects who completed the study. Melatonin decreased sleep latency (Mean difference (MD): 11.4 min, p= 0.02) and WASO (MD 22 min, p=0.04) as compared to placebo. No worsening of spike density or seizure frequency was seen. Additionally, Slow-wave sleep duration and REM latency were increased with melatonin and REM sleep duration was decreased. These changes were statistically significant. Worsening of headache was noted in one subject with migraine on melatonin. Conclusion Sustained-release melatonin resulted in statistically significant decreases in sleep latency and WASO. No clear effects on seizures were observed but the study was too small to allow any conclusions to be drawn in this regard. PMID:25862116

Temperature crossover of decoherence rates in chaotic and regular bath dynamics.

PubMed

Sanz, A S; Elran, Y; Brumer, P

2012-03-01

The effect of chaotic bath dynamics on the decoherence of a quantum system is examined for the vibrational degrees of freedom of a diatomic molecule in a realistic, constant temperature collisional bath. As an example, the specific case of I(2) in liquid xenon is examined as a function of temperature, and the results compared with an integrable xenon bath. A crossover in behavior is found: The integrable bath induces more decoherence at low bath temperatures than does the chaotic bath, whereas the opposite is the case at the higher bath temperatures. These results, verifying a conjecture due to Wilkie, shed light on the differing views of the effect of chaotic dynamics on system decoherence.

Laboratory- and community-based health outcomes in people with transtibial amputation using crossover and energy-storing prosthetic feet: A randomized crossover trial

PubMed Central

Morgan, Sara J.; McDonald, Cody L.; Halsne, Elizabeth G.; Cheever, Sarah M.; Salem, Rana; Kramer, Patricia A.

2018-01-01

Contemporary prosthetic feet are generally optimized for either daily or high-level activities. Prosthesis users, therefore, often require multiple prostheses to participate in activities that span a range of mobility. Crossover feet (XF) are designed to increase the range of activities that can be performed with a single prosthesis. However, little evidence exists to guide clinical prescription of XF relative to traditional energy storing feet (ESF). The objective of this study was to assess the effects of XF and ESF on health outcomes in people with transtibial amputation. A randomized crossover study was conducted to assess changes in laboratory-based (endurance, perceived exertion, walking performance) and community-based (step activity and self-reported mobility, fatigue, balance confidence, activity restrictions, and satisfaction) outcomes. Twenty-seven participants were fit with XF and ESF prostheses with standardized sockets, interfaces, and suspensions. Participants were not blinded to the intervention, and wore each prosthesis for one month while their steps were counted with an activity monitor. After each accommodation period, participants returned for data collection. Endurance and perceived exertion were measured with the Six-Minute Walk Test and Borg-CR100, respectively. Walking performance was measured using an electronic walkway. Self-reported mobility, fatigue, balance confidence, activity restrictions, and satisfaction were measured with survey instruments. Participants also reported foot preferences upon conclusion of the study. Differences between feet were assessed with a crossover analysis. While using XF, users experienced improvements in most community-based outcomes, including mobility (p = .001), fatigue (p = .001), balance confidence (p = .005), activity restrictions (p = .002), and functional satisfaction (p < .001). Participants also exhibited longer sound side steps in XF compared to ESF (p < .001). Most participants (89%) reported an overall preference for XF; others (11%) reported no preference. Results indicate that XF may be a promising alternative to ESF for people with transtibial amputation who engage in a range of mobility activities. Trial registration: ClinicalTrials.gov NCT02440711 PMID:29414988

A CASE-CROSSOVER STUDY OF THE RELATIONSHIP OF FINE PM LEVELS TO SUDDEN CARDIAC ARREST IN INDIVIDUALS WITH AND WITHOUT CARDIAC DISEASE. (R827355C001)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

Thermal hysteresis kinetic effects of spin crossover nanoparticulated systems studied by FORC diagram method on an Ising-like model

NASA Astrophysics Data System (ADS)

Atitoaie, Alexandru; Stoleriu, Laurentiu; Tanasa, Radu; Stancu, Alexandru; Enachescu, Cristian

2016-04-01

The scientific community is manifesting a high research interest on spin crossover compounds and their recently synthesized nanoparticles, due to their various appealing properties, such as the bistability between a diamagnetic low spin state and a paramagnetic high spin state (HS), inter-switchable by temperature or pressure changes, light irradiation or magnetic field. The utility of these compounds showing hysteresis covers a broad area of applications, from the development of more efficient designs of temperature and pressure sensors to automotive and aeronautic industries and even a new type of molecular actuators. We are proposing in this work a study regarding the kinetic effects and the distribution of reversible and irreversible components on the thermal hysteresis of spin crossover nanoparticulated systems. We are considering here tridimensional systems with different sizes and also systems of nanoparticles with a Gaussian size distribution. The correlations between the kinetics of the thermal hysteresis, the distributions of sizes and intermolecular interactions and the transition temperature distributions were established by using the FORC (First Order Reversal Curves) method using a Monte Carlo technique within an Ising-like system.

Improved Cathode Structure for a Direct Methanol Fuel Cell

NASA Technical Reports Server (NTRS)

Valdez, Thomas; Narayanan, Sekharipuram

2005-01-01

An improved cathode structure on a membrane/electrode assembly has been developed for a direct methanol fuel cell, in a continuing effort to realize practical power systems containing such fuel cells. This cathode structure is intended particularly to afford better cell performance at a low airflow rate. A membrane/electrode assembly of the type for which the improved cathode structure was developed (see Figure 1) is fabricated in a process that includes brush painting and spray coating of catalyst layers onto a polymer-electrolyte membrane and onto gas-diffusion backings that also act as current collectors. The aforementioned layers are then dried and hot-pressed together. When completed, the membrane/electrode assembly contains (1) an anode containing a fine metal black of Pt/Ru alloy, (2) a membrane made of Nafion 117 or equivalent (a perfluorosulfonic acid-based hydrophilic, proton-conducting ion-exchange polymer), (3) a cathode structure (in the present case, the improved cathode structure described below), and (4) the electrically conductive gas-diffusion backing layers, which are made of Toray 060(TradeMark)(or equivalent) carbon paper containing between 5 and 6 weight percent of poly(tetrafluoroethylene). The need for an improved cathode structure arises for the following reasons: In the design and operation of a fuel-cell power system, the airflow rate is a critical parameter that determines the overall efficiency, cell voltage, and power density. It is desirable to operate at a low airflow rate in order to obtain thermal and water balance and to minimize the size and mass of the system. The performances of membrane/electrode assemblies of prior design are limited at low airflow rates. Methanol crossover increases the required airflow rate. Hence, one way to reduce the required airflow rate is to reduce the effect of methanol crossover. Improvement of the cathode structure - in particular, addition of hydrophobic particles to the cathode - has been demonstrated to mitigate the effects of crossover and decrease the airflow required.

Comparison of 2 resident learning tools-interactive screen-based simulated case scenarios versus problem-based learning discussions: a prospective quasi-crossover cohort study.

PubMed

Rajan, Shobana; Khanna, Ashish; Argalious, Maged; Kimatian, Stephen J; Mascha, Edward J; Makarova, Natalya; Nada, Eman M; Elsharkawy, Hesham; Firoozbakhsh, Farhad; Avitsian, Rafi

2016-02-01

Simulation-based learning is emerging as an alternative educational tool in this era of a relative shortfall of teaching anesthesiologists. The objective of the study is to assess whether screen-based (interactive computer simulated) case scenarios are more effective than problem-based learning discussions (PBLDs) in improving test scores 4 and 8 weeks after these interventions in anesthesia residents during their first neuroanesthesia rotation. Prospective, nonblinded quasi-crossover study. Cleveland Clinic. Anesthesiology residents. Two case scenarios were delivered from the Anesoft software as screen-based sessions, and parallel scripts were developed for 2 PBLDs. Each resident underwent both types of training sessions, starting with the PBLD session, and the 2 cases were alternated each month (ie, in 1 month, the screen-based intervention used case 1 and the PBLD used case 2, and vice versa for the next month). Test scores before the rotation (baseline), immediately after the rotation (4 weeks after the start of the rotation), and 8 weeks after the start of rotation were collected on each topic from each resident. The effect of training method on improvement in test scores was assessed using a linear mixed-effects model. Compared to the departmental standard of PBLD, the simulation method did not improve either the 4- or 8-week mean test scores (P = .41 and P = .40 for training method effect on 4- and 8-week scores, respectively). Resident satisfaction with the simulation module on a 5-point Likert scale showed subjective evidence of a positive impact on resident education. Screen-based simulators were not more effective than PBLD for education during the neuroanesthesia rotation in anesthesia residency. Copyright © 2016 Elsevier Inc. All rights reserved.

Self-Administered Computer Therapy for Apraxia of Speech: Two-Period Randomized Control Trial With Crossover.

PubMed

Varley, Rosemary; Cowell, Patricia E; Dyson, Lucy; Inglis, Lesley; Roper, Abigail; Whiteside, Sandra P

2016-03-01

There is currently little evidence on effective interventions for poststroke apraxia of speech. We report outcomes of a trial of self-administered computer therapy for apraxia of speech. Effects of speech intervention on naming and repetition of treated and untreated words were compared with those of a visuospatial sham program. The study used a parallel-group, 2-period, crossover design, with participants receiving 2 interventions. Fifty participants with chronic and stable apraxia of speech were randomly allocated to 1 of 2 order conditions: speech-first condition versus sham-first condition. Period 1 design was equivalent to a randomized controlled trial. We report results for this period and profile the effect of the period 2 crossover. Period 1 results revealed significant improvement in naming and repetition only in the speech-first group. The sham-first group displayed improvement in speech production after speech intervention in period 2. Significant improvement of treated words was found in both naming and repetition, with little generalization to structurally similar and dissimilar untreated words. Speech gains were largely maintained after withdrawal of intervention. There was a significant relationship between treatment dose and response. However, average self-administered dose was modest for both groups. Future software design would benefit from incorporation of social and gaming components to boost motivation. Single-word production can be improved in chronic apraxia of speech with behavioral intervention. Self-administered computerized therapy is a promising method for delivering high-intensity speech/language rehabilitation. URL: http://orcid.org/0000-0002-1278-0601. Unique identifier: ISRCTN88245643. © 2016 American Heart Association, Inc.

Development of an LYSO based gamma camera for positron and scinti-mammography

NASA Astrophysics Data System (ADS)

Liang, H.-C.; Jan, M.-L.; Lin, W.-C.; Yu, S.-F.; Su, J.-L.; Shen, L.-H.

2009-08-01

In this research, characteristics of combination of PSPMTs (position sensitive photo-multiplier tube) to form a larger detection area is studied. A home-made linear divider circuit was built for merging signals and readout. Borosilicate glasses were chosen for the scintillation light sharing in the crossover region. Deterioration effect caused by the light guide was understood. The influences of light guide and crossover region on the separable crystal size were evaluated. According to the test results, a gamma camera with a crystal block of 90 × 90 mm2 covered area, composed of 2 mm LYSO crystal pixels, was designed and fabricated. Measured performances showed that this camera worked fine in both 511 keV and lower energy gammas. The light loss behaviour within the crossover region was analyzed and realized. Through count rate measurements, the 176Lu nature background didn't show severe influence on the single photon imaging and exhibited an amount of less than 1/3 of all the events acquired. These results show that with using light sharing techniques, combination of multiple PSPMTs in both X and Y directions to build a large area imaging detector is capable to be achieved. Also this camera design is feasible to keep both the abilities for positron and single photon breast imaging applications. Separable crystal size is 2 mm with 2 mm thick glass applied for the light sharing in current status.

Association between wind speed and the occurrence of sickle cell acute painful episodes: results of a case-crossover study

PubMed Central

Nolan, Vikki G.; Zhang, Yuqing; Lash, Timothy; Sebastiani, Paola; Steinberg, Martin H.

2015-01-01

Summary The role of the weather as a trigger of sickle cell acute painful episodes has long been debated. To more accurately describe the role of the weather as a trigger of painful events, we conducted a case-crossover study of the association between local weather conditions and the occurrence of painful episodes. From the Cooperative Study of Sickle Cell Disease, we identified 813 patients with sickle cell anaemia who had 3570 acute painful episodes. We found an association between wind speed and the onset of pain, specifically wind speed during the 24-h period preceding the onset of pain. Analysing wind speed as a categorical trait, showed a 13% increase (95% confidence interval: 3%, 24%) in odds of pain, when comparing the high wind speed to lower wind speed (P = 0.007). In addition, the association between wind speed and painful episodes was found to be stronger among men, particularly those in the warmer climate regions of the United States. These results are in agreement with another study that found an association between wind speed and hospital visits for pain in the United Kingdom, and lends support to physiological and clinical studies that have suggested that skin cooling is associated with sickle vasoocclusion and perhaps pain. PMID:18729854

Association between wind speed and the occurrence of sickle cell acute painful episodes: results of a case-crossover study.

PubMed

Nolan, Vikki G; Zhang, Yuqing; Lash, Timothy; Sebastiani, Paola; Steinberg, Martin H

2008-11-01

The role of the weather as a trigger of sickle cell acute painful episodes has long been debated. To more accurately describe the role of the weather as a trigger of painful events, we conducted a case-crossover study of the association between local weather conditions and the occurrence of painful episodes. From the Cooperative Study of Sickle Cell Disease, we identified 813 patients with sickle cell anaemia who had 3570 acute painful episodes. We found an association between wind speed and the onset of pain, specifically wind speed during the 24-h period preceding the onset of pain. Analysing wind speed as a categorical trait, showed a 13% increase (95% confidence interval: 3%, 24%) in odds of pain, when comparing the high wind speed to lower wind speed (P = 0.007). In addition, the association between wind speed and painful episodes was found to be stronger among men, particularly those in the warmer climate regions of the United States. These results are in agreement with another study that found an association between wind speed and hospital visits for pain in the United Kingdom, and lends support to physiological and clinical studies that have suggested that skin cooling is associated with sickle vasoocclusion and perhaps pain.

Training Verbal and Nonverbal Communication Interview Skills to Adolescents

ERIC Educational Resources Information Center

Olszewski, Abbie; Panorska, Anna; Gillam, Sandra Laing

2017-01-01

Adolescents' verbal and nonverbal communication skills were compared before and after training in a workforce readiness training program, Language for Scholars (LFS), and a study skills program, Ideal Student Workshop (ISW). A cross-over design was used, ensuring that 44 adolescents received both programs and acted as their own control. The LFS…

Exploring Student Perceptions of Audiovisual Feedback via Screencasting in Online Courses

ERIC Educational Resources Information Center

Mathieson, Kathleen

2012-01-01

Using Moore's (1993) theory of transactional distance as a framework, this action research study explored students' perceptions of audiovisual feedback provided via screencasting as a supplement to text-only feedback. A crossover design was employed to ensure that all students experienced both text-only and text-plus-audiovisual feedback and to…

Encouraging Girls to Consider a Career in ICT: A Review of Strategies

ERIC Educational Resources Information Center

Miliszewska, Iwona; Moore, Aidan

2010-01-01

This article reviews strategies designed to improve female participation in ICT studies and careers. In reviewing a range of strategies from around the world, the article identifies the different actors engaging with the "problem" of girls and technology. It points to the many crossovers that occur as governments, higher education…

Application of Crossover Design for Conducting Rigorous Extension Evaluations

ERIC Educational Resources Information Center

Jayaratne, K. S. U.; Bird, Carolyn L.; McClelland, Jacquelyn W.

2013-01-01

With the increasing demand for accountability of Extension programming, Extension professionals need to apply rigorous evaluation designs. Randomized designs are useful to eliminate selection biases of program participants and to improve the accuracy of evaluation. However, randomized control designs are not practical to apply in Extension program…

Association between flood and the morbidity of bacillary dysentery in Zibo City, China: a symmetric bidirectional case-crossover study

NASA Astrophysics Data System (ADS)

Zhang, Feifei; Ding, Guoyong; Liu, Zhidong; Zhang, Caixia; Jiang, Baofa

2016-12-01

This study examined the relationship between daily morbidity of bacillary dysentery and flood in 2007 in Zibo City, China, using a symmetric bidirectional case-crossover study. Odds ratios (ORs) and 95 % confidence intervals (CIs) on the basis of multivariate model and stratified analysis at different lagged days were calculated to estimate the risk of flood on bacillary dysentery. A total of 902 notified bacillary dysentery cases were identified during the study period. The median of case distribution was 7-year-old and biased to children. Multivariable analysis showed that flood was associated with an increased risk of bacillary dysentery, with the largest OR of 1.849 (95 % CI 1.229-2.780) at 2-day lag. Gender-specific analysis showed that there was a significant association between flood and bacillary dysentery among males only (ORs >1 from lag 1 to lag 5), with the strongest lagged effect at 2-day lag (OR = 2.820, 95 % CI 1.629-4.881), and the result of age-specific indicated that youngsters had a slightly larger risk to develop flood-related bacillary dysentery than older people at one shorter lagged day (OR = 2.000, 95 % CI 1.128-3.546 in youngsters at lag 2; OR = 1.879, 95 % CI 1.069-3.305 in older people at lag 3). Our study has confirmed that there is a positive association between flood and the risk of bacillary dysentery in selected study area. Males and youngsters may be the vulnerable and high-risk populations to develop the flood-related bacillary dysentery. Results from this study will provide recommendations to make available strategies for government to deal with negative health outcomes due to floods.

Association between flood and the morbidity of bacillary dysentery in Zibo City, China: a symmetric bidirectional case-crossover study.

PubMed

Zhang, Feifei; Ding, Guoyong; Liu, Zhidong; Zhang, Caixia; Jiang, Baofa

2016-12-01

This study examined the relationship between daily morbidity of bacillary dysentery and flood in 2007 in Zibo City, China, using a symmetric bidirectional case-crossover study. Odds ratios (ORs) and 95 % confidence intervals (CIs) on the basis of multivariate model and stratified analysis at different lagged days were calculated to estimate the risk of flood on bacillary dysentery. A total of 902 notified bacillary dysentery cases were identified during the study period. The median of case distribution was 7-year-old and biased to children. Multivariable analysis showed that flood was associated with an increased risk of bacillary dysentery, with the largest OR of 1.849 (95 % CI 1.229-2.780) at 2-day lag. Gender-specific analysis showed that there was a significant association between flood and bacillary dysentery among males only (ORs >1 from lag 1 to lag 5), with the strongest lagged effect at 2-day lag (OR = 2.820, 95 % CI 1.629-4.881), and the result of age-specific indicated that youngsters had a slightly larger risk to develop flood-related bacillary dysentery than older people at one shorter lagged day (OR = 2.000, 95 % CI 1.128-3.546 in youngsters at lag 2; OR = 1.879, 95 % CI 1.069-3.305 in older people at lag 3). Our study has confirmed that there is a positive association between flood and the risk of bacillary dysentery in selected study area. Males and youngsters may be the vulnerable and high-risk populations to develop the flood-related bacillary dysentery. Results from this study will provide recommendations to make available strategies for government to deal with negative health outcomes due to floods.

Studies on Methanol Crossover in Liquid-Feed Direct Methanol Pem Fuel Cells

NASA Technical Reports Server (NTRS)

Narayanan, S. R.

1995-01-01

The performance of liquid feed direct methanol fuel cells using various types of Nafion membranes as the solid polymer electrolyte have been studied. The rate of fuel crossover and electrical performance has been measured for cells with Nafion membranes of various thicknesses and equivalent weights. The crossover rate is found to decrease with increasing thickness and applied current. The dependence of crossover rate on current density can be understood in terms of a simple linear diffusion model which suggests that the crossover rate can be influenced by the electrode structure in addition to the membrane. The studies suggest that Nafion EW 1500 is a very promising alternate to Nafion EW 1100 for direct methanol fuel cells.

Effect of sex, age and genetics on crossover interference in cattle

PubMed Central

Wang, Zhiying; Shen, Botong; Jiang, Jicai; Li, Jinquan; Ma, Li

2016-01-01

Crossovers generated by homologous recombination ensure proper chromosome segregation during meiosis. Crossover interference results in chiasmata being more evenly distributed along chromosomes, but the mechanism underlying crossover interference remains elusive. Based on large pedigrees of Holstein and Jersey cattle with genotype data, we extracted three-generation families, including 147,327 male and 71,687 female meioses in Holstein, and 108,163 male and 37,008 female meioses in Jersey, respectively. We identified crossovers in these meioses and fitted the Housworth-Stahl “interference-escape” model to study crossover interference patterns in the cattle genome. Our result reveals that the degree of crossover interference is stronger in females than in males. We found evidence for inter-chromosomal variation in the level of crossover interference, with smaller chromosomes exhibiting stronger interference. In addition, crossover interference levels decreased with maternal age. Finally, sex-specific GWAS analyses identified one locus near the NEK9 gene on chromosome 10 to have a significant effect on crossover interference levels. This locus has been previously associated with recombination rate in cattle. Collectively, this large-scale analysis provided a comprehensive description of crossover interference across chromosome, sex and age groups, identified associated candidate genes, and produced useful insights into the mechanism of crossover interference. PMID:27892966

What's Mine Is Yours: The Crossover of Day-Specific Self-Esteem

ERIC Educational Resources Information Center

Neff, Angela; Sonnentag, Sabine; Niessen, Cornelia; Unger, Dana

2012-01-01

This diary study examines the daily crossover of self-esteem within working couples. By integrating self-esteem research into the crossover framework, we hypothesized that the day-specific self-esteem experienced by one partner after work crosses over to the other partner. Furthermore, we proposed that this daily crossover process is moderated by…

Periodic density functional theory study of spin crossover in the cesium iron hexacyanochromate prussian blue analog

NASA Astrophysics Data System (ADS)

Wojdeł, Jacek C.; Moreira, Ibério de P. R.; Illas, Francesc

2009-01-01

This paper presents a detailed theoretical analysis of the electronic structure of the CsFe[Cr(CN)6] prussian blue analog with emphasis on the structural origin of the experimentally observed spin crossover transition in this material. Periodic density functional calculations using generalized gradient approximation (GGA)+U and nonlocal hybrid exchange-correlation potentials show that, for the experimental low temperature crystal structure, the t2g6eg0 low spin configuration of FeII is the most stable and CrIII (S =3/2, t2g3eg0) remains the same in all cases. This is also found to be the case for the low spin GGA+U fully relaxed structure with the optimized unit cell. A completely different situation emerges when calculations are carried out using the experimental high temperature structure. Here, GGA+U and hybrid density functional theory calculations consistently predict that the t2g4eg2 FeII high spin configuration is the ground state. However, the two spin configurations appear to be nearly degenerate when calculations are carried out for the geometries arising from a GGA+U full relaxation of the atomic structure carried out at experimental high temperature lattice constant. A detailed analysis of the energy difference between the two spin configurations as a function of the lattice constant strongly suggests that the observed spin crossover transition has a structural origin with non-negligible entropic contributions of the high spin state.

[Urban air pollution and children respiratory hospital admissions in Pisa (Italy): a time series and a case-crossover approach].

PubMed

Vigotti, Maria Angela; Serinelli, Maria; Marchini, Laura

2010-01-01

we evaluated the association of daily pollutants' concentrations with daily hospital admissions for respiratory causes in children residents in Pisa during 1998-2002. We compared the results obtained with two methods of statistical analyses. A total of 657 children under ten years and admitted to local hospitals for respiratory diseases (ICD 9: 460-469, 480- 519) were included in the study. both time-series and case-crossover analysis were applied, controlling for temperature, holidays, influenza epidemics,rain and relative humidity. Pollutants' effects are expressed as percentage increase (and 95% CI) of hospital admissions for an increase of 10 μg/m³ of pollutants (1 mg/m³ for CO). with both analyses, children's hospital admissions for respiratory conditions were significantly associated to increasing daily levels of PM10 and CO at different time lags, while no association was found for NO₂ and O₃. In the case-crossover analysis, for a daily increase of 10 μg/m³ in PM10, a significant increment of 8.5% (CI 95% 0.02; 17.6) in children respiratory admissions was observed at lag 0-3. Results were stronger for males and during the warm season. A 1 mg/m³ increment in daily CO levels was associated with an increase of respiratory admissions at lag 0 (20.2%, CI 95% 5.3; 37.2) and at all cumulative lags: the maximum value was observed at lag 0-3 (32.6%, CI 95%8.3; 62.2). Time series analyses provides similar results, although the estimates were lower than with the other method, in terms of percentage increment and length of confidence intervals. this study indicates adverse effects of air pollution on respiratory health of children living in urban environment. The results of both analyses were consistent.

Stress Crossover in Newlywed Marriage: A Longitudinal and Dyadic Perspective

ERIC Educational Resources Information Center

Neff, Lisa A.; Karney, Benjamin R.

2007-01-01

Studies of stress and marital quality often assess stress as an intrapersonal phenomenon, examining how spouses' stress may influence their own relationship well-being. Yet spouses' stress also may influence partners' relationship evaluations, a phenomenon referred to as stress crossover. This study examined stress crossover, and conditions that…

Design, analysis, and testing of high frequency passively damped struts

NASA Technical Reports Server (NTRS)

Yiu, Y. C.; Davis, L. Porter; Napolitano, Kevin; Ninneman, R. Rory

1993-01-01

Objectives of the research are: (1) to develop design requirements for damped struts to stabilize control system in the high frequency cross-over and spill-over range; (2) to design, fabricate and test viscously damped strut and viscoelastically damped strut; (3) to verify accuracy of design and analysis methodology of damped struts; and (4) to design and build test apparatus, and develop data reduction algorithm to measure strut complex stiffness. In order to meet the stringent performance requirements of the SPICE experiment, the active control system is used to suppress the dynamic responses of the low order structural modes. However, the control system also inadvertently drives some of the higher order modes unstable in the cross-over and spill-over frequency range. Passive damping is a reliable and effective way to provide damping to stabilize the control system. It also improves the robustness of the control system. Damping is designed into the SPICE testbed as an integral part of the control-structure technology.

In silico modelling of directed evolution: Implications for experimental design and stepwise evolution.

PubMed

Wedge, David C; Rowe, William; Kell, Douglas B; Knowles, Joshua

2009-03-07

We model the process of directed evolution (DE) in silico using genetic algorithms. Making use of the NK fitness landscape model, we analyse the effects of mutation rate, crossover and selection pressure on the performance of DE. A range of values of K, the epistatic interaction of the landscape, are considered, and high- and low-throughput modes of evolution are compared. Our findings suggest that for runs of or around ten generations' duration-as is typical in DE-there is little difference between the way in which DE needs to be configured in the high- and low-throughput regimes, nor across different degrees of landscape epistasis. In all cases, a high selection pressure (but not an extreme one) combined with a moderately high mutation rate works best, while crossover provides some benefit but only on the less rugged landscapes. These genetic algorithms were also compared with a "model-based approach" from the literature, which uses sequential fixing of the problem parameters based on fitting a linear model. Overall, we find that purely evolutionary techniques fare better than do model-based approaches across all but the smoothest landscapes.

Intravenous subhypnotic propofol in central pain: a double-blind, placebo-controlled, crossover study.

PubMed

Canavero, S; Bonicalzi, V

2004-01-01

To validate IV subhypnotic propofol, a gamma-aminobutyric acid A (GABA-A) agonist, as a diagnostic test for central pain. The efficacy of systemic propofol (0.2 mg/kg IV bolus) was evaluated in a double-blind, placebo-controlled and crossover fashion on both spontaneous ongoing pain and allodynia in 44 patients with chronic central pain of both brain and cord origin. Propofol was significantly superior to the placebo (Intralipid, Kabi Pharmacia) in reducing the intensity of spontaneous ongoing pain for up to 1 hour after the injection: 24 of 44 patients (55%) receiving propofol showed a significant reduction in spontaneous pain, whereas only 6 patients showed this after the placebo. Propofol also significantly reduced the intensity of both mechanical and cold allodynia. In a few cases, only the evoked components were abolished but not the spontaneous pain. In general, the side effects were minimal and consisted mainly of transitory burning upon injection of both propofol and placebo and slight lightheadedness in a few cases. Systemic propofol induces analgesic effects on all studied components of central pain and highlights the key role of GABA modulation in central pain.

Small cause - big effect: improvement in interface design results in improved data quality - a multicenter crossover study.

PubMed

Ahlbrandt, Janko; Henrich, Michael; Hartmann, Bernd A; Bundschuh, Bettina B; Schwarz, Julia; Klasen, Joachim; Röhrig, Rainer

2012-01-01

In Germany the core data set for anesthesia version 3.0 was recently introduced for external quality assurance, which includes five surgical tracer procedures. We found a low rate of correctly documented tracers when compared to procedure data (OPS-Codes) documented separately. Examination revealed that the graphical user interface (GUI) contravened the dialogue principles as defined in EN ISO 9241-110. We worked with the manufacturer to implement small improvements and roll out the software. A crossover study was conducted at a university hospital and a municipal hospital chain with five hospitals. All study sites and surgical tracer procedures combined, we found an improvement from 42% to 65% (p<0.001; N=34,610) correctly documented anesthesias. We also saw improvements for most of the observed surgical tracer procedures at all hospitals. Our results show the big effect small changes to the GUI can have on data quality. They also raise the question, if highly flexible and parameterized clinical documentation systems are suited to achieve high usability. Finding the right balance between GUIs designed by usability experts and the flexibility of parameterization by administrators will be a difficult task for the future and subject to further research.

Air pollution by particulate matter PM10 may trigger multiple sclerosis relapses.

PubMed

Roux, Jonathan; Bard, Denis; Le Pabic, Estelle; Segala, Claire; Reis, Jacques; Ongagna, Jean-Claude; de Sèze, Jérôme; Leray, Emmanuelle

2017-07-01

Seasonal variation of relapses in multiple sclerosis (MS) suggests that season-dependent factors, such as ambient air pollution, may trigger them. However, only few studies have considered possible role of air pollutants as relapse's risk factor. We investigated the effect of particulate matter of aerodynamic diameter smaller than 10µm (PM 10 ) on MS relapses. In total, 536 relapsing MS patients from Strasbourg city (France) were included, accounting for 2052 relapses over 2000-2009 period. A case-crossover design was used with cases defined as the days of relapse and controls being selected in the same patient at plus and minus 35 days. Different lags from 0 to 30 days were considered. Conditional logistic regressions, adjusted on meteorological parameters, school and public holidays, were used and exposure was considered first as a quantitative variable and second, as a binary variable. The natural logarithm of the average PM 10 concentration lagged from 1 to 3 days before relapse onset was significantly associated with relapse risk (OR =1.40 [95% confidence interval 1.08-1.81]) in cold season. Consistent results were observed when considering PM 10 as a binary variable, even if not significant. With an appropriate study design and robust ascertainment of neurological events and exposure, the present study highlights the effect of PM 10 on the risk of relapse in MS patients, probably through oxidative stress mechanisms. Copyright © 2017 Elsevier Inc. All rights reserved.

Auditory and Visual Attention Performance in Children With ADHD: The Attentional Deficiency of ADHD Is Modality Specific.

PubMed

Lin, Hung-Yu; Hsieh, Hsieh-Chun; Lee, Posen; Hong, Fu-Yuan; Chang, Wen-Dien; Liu, Kuo-Cheng

2017-08-01

This study explored auditory and visual attention in children with ADHD. In a randomized, two-period crossover design, 50 children with ADHD and 50 age- and sex-matched typically developing peers were measured with the Test of Various Attention (TOVA). The deficiency of visual attention is more serious than that of auditory attention in children with ADHD. On the auditory modality, only the deficit of attentional inconsistency is sufficient to explain most cases of ADHD; however, most of the children with ADHD suffered from deficits of sustained attention, response inhibition, and attentional inconsistency on the visual modality. Our results also showed that the deficit of attentional inconsistency is the most important indicator in diagnosing and intervening in ADHD when both auditory and visual modalities are considered. The findings provide strong evidence that the deficits of auditory attention are different from those of visual attention in children with ADHD.

The Effect of Music Therapy Services on Classroom Behaviours of Newly Arrived Refugee Students in Australia--A Pilot Study

ERIC Educational Resources Information Center

Baker, Felicity; Jones, Carolyn

2006-01-01

This pilot study examined the effects of a short-term music therapy program on the classroom behaviours of newly arrived refugee students who were attending an intensive "English as a Second Language" secondary school. A cross-over design with two five-week intervention periods was employed with group music therapy sessions conducted one…

The effectiveness of dopamine agonists for treatment of neuropsychiatric symptoms post brain injury and stroke.

PubMed

Sami, Musa Basseer; Faruqui, Rafey

2015-12-01

Traumatic brain injury and stroke are among the leading causes of neurological disability worldwide. Although dopaminergic agents have long been associated with improvement of neuropsychiatric outcomes, to date much of the evidence to date has been in case reports and case series or open label trials. We undertook a systematic review of double-blinded randomised controlled trials (RCT) to determine the effect of dopaminergic agents on pre-defined outcomes of (a) apathy; (b) psychomotor retardation; (c) behavioural management and (d) cognitive function. Databases searched were: Medline, EMBASE, and PsychInfo for human studies. The Cochrane Clinical Trials Database and the TRIP Medical database were also searched. All identified studies, were further hand-searched. We identified six studies providing data on 227 participants, 150 of whom received dopaminergic therapy. Trials were compromised by cross-over design, inadequate wash out period, small numbers and heterogeneous outcome measures. However one good quality RCT demonstrates the efficacy of amantadine in behavioural management. One further RCT shows methylphenidate-levodopa is efficacious for mood post-stroke. One study shows rotigotine to improve hemi-inattention caused by prefrontal damage. Our systematic review demonstrates an evolving evidence base to suggest some benefits in agitation and aggression, mood and attentional deficits. However, there are key limitations of the studies undertaken to date involving small numbers of participants, heterogeneous outcome measures, and variable study designs. There is a need for on-going large prospective double-blind RCTs in these medications using standardised criteria and outcomes to fully understand their effectiveness in this patient group.

The association between daily concentrations of air pollution and visits to a psychiatric emergency unit: a case-crossover study.

PubMed

Oudin, Anna; Åström, Daniel Oudin; Asplund, Peter; Steingrimsson, Steinn; Szabo, Zoltan; Carlsen, Hanne Krage

2018-01-10

Air pollution is one of the leading causes of mortality and morbidity worldwide. Experimental studies, and a few epidemiological studies, suggest that air pollution may cause acute exacerbation of psychiatric disorders, and even increase the rate of suicide attempts, but epidemiological studies on air pollution in association with psychiatric disorders are still few. Our aim was to investigate associations between daily fluctuations in air pollution concentrations and the daily number of visits to a psychiatric emergency unit. Data from Sahlgrenska University Hospital, Gothenburg, Sweden, on the daily number of visits to the Psychiatric emergency unit were combined with daily data on monitored concentrations of respirable particulate matter(PM 10 ), ozone(O 3 ), nitrogen dioxides(NO 2 ) and temperature between 1st July 2012 and 31st December 2016. We used a case-crossover design to analyze data with conditional Poisson regression models allowing for over-dispersion. We stratified data on season. Visits increased with increasing PM 10 levels during the warmer season (April to September) in both single-pollutant and two-pollutant models. For example, an increase of 3.6% (95% Confidence Interval, CI, 0.4-7.0%) was observed with a 10 μg/m3 increase in PM 10 adjusted for NO 2 . In the three-pollutant models (adjusting for NO 2 and O 3 simultaneously) the increase was 3.3% (95% CI, -0.2-6.9). There were no clear associations between the outcome and NO 2 , O 3 , or PM 10 during the colder season (October to March). Ambient air particle concentrations were associated with the number of visits to the Psychiatric emergency unit in the warm season. The results were only borderline statistically significant in the fully adjusted (three-pollutant) models in this small study. The observation could be interpreted as indicative of air pollution as either exacerbating an underlying psychiatric disorder, or increasing mental distress, even in areas with comparatively low levels of air pollution. In combination with the severe impact of psychiatric disorders and mental distress on society and individuals, our results are a strong warrant for future research in this area.

An exploratory pilot study to design and assess the credibility of a sham kinesiology treatment.

PubMed

Hall, Sue; Lewith, George; Brien, Sarah; Little, Paul

2008-12-01

Kinesiology is a complementary therapy assessing subtle change in manual muscle testing results to select individualised treatments. We report the exploratory 2-stage development and pilot of a sham kinesiology treatment for use in a clinical trial to evaluate the specific effects of this intervention. 1. To design, pilot and assess the credibility of a sham kinesiology treatment in a kinesiology-aware population. 2. To pilot the sham kinesiology in a cross-over study of sham versus real kinesiology, and to make an exploratory assessment of its credibility in a kinesiology-naïve population. 1. 10 kinesiology-aware volunteers received a specially designed sham treatment weekly for 5 weeks which was subject to a credibility assessment. 2. 10 kinesiology-naïve patients with low back pain were randomised to receive 4 real and 4 sham treatments in a cross-over design; the treatments were subject to a credibility assessment. 100% of participants found the sham protocol a credible treatment as measured by the credibility questionnaire. 100% of patients having real treatment first did not recognise that the second set of treatments were sham. Small numbers precluded the use of formal statistical tests. In this small sample it appeared feasible to deliver an apparently credible sham kinesiology treatment. This feasibility study has allowed us to develop a sham treatment for use in a larger prospective clinical trial of kinesiology in patients with low back pain. 2008 S. Karger AG, Basel.

Air Pollution and Subtypes, Severity and Vulnerability to Ischemic Stroke—A Population Based Case-Crossover Study

PubMed Central

Maheswaran, Ravi; Pearson, Tim; Beevers, Sean D.; Campbell, Michael J.; Wolfe, Charles D.

2016-01-01

Background and Purpose Few studies have examined the association between air pollutants and ischemic stroke subtypes. We examined acute effects of outdoor air pollutants (PM10, NO2, O3, CO, SO2) on subtypes and severity of incident ischemic stroke and investigated if pre-existing risk factors increased susceptibility. Methods We used a time stratified case-crossover study and stroke cases from the South London Stroke Register set up to capture all incident cases of first ever stroke occurring amongst residents in a geographically defined area. The Oxford clinical and TOAST etiological classifications were used to classify subtypes. A pragmatic clinical classification system was used to assess severity. Air pollution concentrations from the nearest background air pollution monitoring stations to patients’ residential postcode centroids were used. Lags from 0 to 6 days were investigated. Results There were 2590 incident cases of ischemic stroke (1995–2006). While there were associations at various lag times with several pollutants, overall, there was no consistent pattern between exposure and risk of ischemic stroke subtypes or severity. The possible exception was the association between NO2 exposure and small vessel disease stroke—adjusted odds ratio of 1.51 (1.12–2.02) associated with an inter-quartile range increase in the lag 0–6 day average for NO2. There were no clear associations in relation to pre-existing risk factors. Conclusions Overall, we found little consistent evidence of association between air pollutants and ischemic stroke subtypes and severity. There was however a suggestion that increasing NO2 exposure might be associated with higher risk of stroke caused by cerebrovascular small vessel disease. PMID:27362783

Online Instructional Videos as a Complimentary Method of Teaching Practical Rehabilitation Skills for Groups and Individuals

ERIC Educational Resources Information Center

Cooper, Darren; Higgins, Steve; Beckmann, Nadin

2017-01-01

Online instructional videos are becoming increasingly common within education. This study adopts a quasi-experimental 2 × 2 crossover design (control and experimental groups) to evaluate the efficacy of instructional videos to teach practical rehabilitation skills. The students performed practical sessions in class and were formatively assessed by…

Effects of MPH-OROS on the Organizational, Time Management, and Planning Behaviors of Children with ADHD

ERIC Educational Resources Information Center

Abikoff, Howard; Nissley-Tsiopinis, Jenelle; Gallagher, Richard; Zambenedetti, Maurizio; Seyffert, Michael; Boorady, Roy; McCarthy, John

2009-01-01

A double-blind, placebo-controlled, crossover design study was done to evaluate the effects of methylphenidate-osmotic-release oral systems (MPH-OROS) on the organization, time management, and planning (OTMP) of children with attention deficit hyperactivity disorder (ADHD). Results show significant improvements on the OTMP of children with ADHD in…

Association of Situational and Environmental Factors With Last Episode of Unprotected Anal Intercourse Among MSM in Hong Kong: A Case-Crossover Analysis.

PubMed

Lau, Joseph T F; Mo, Phoenix K H; Gu, Jing; Hao, Chun; Lai, CoCo H Y

2016-02-01

This study investigates event-specific factors that differentiate the last episodes of unprotected anal intercourse (UAI) from protected anal intercourse (PAI) with regular partner (RP) among 213 men who have sex with men (MSM) who did not use condoms consistently using case-crossover analysis. Factors positively associated with the last episode of UAI with RP included: two situational factors (i.e., participant's suggestion to have UAI, alcohol use) and three environmental/setting factors (i.e., sex took place overseas, during a weekday and not at home). Negative associations with an episode of UAI with RP included: five situational factors (i.e., discussion about condom use prior to sex, RP's suggestion to have PAI, participant's suggestion to have PAI, perception that RP would like to use a condom, participant's planning to use a condom) and two environmental/setting factors (i.e., condoms placed at the venue where sex took place, partner possessed a condom). Thus, these significant event-specific factors explained under which circumstances some MSM would use and would not use condoms during anal sex with RP.

Regulation of spatial selectivity by crossover inhibition.

PubMed

Cafaro, Jon; Rieke, Fred

2013-04-10

Signals throughout the nervous system diverge into parallel excitatory and inhibitory pathways that later converge on downstream neurons to control their spike output. Converging excitatory and inhibitory synaptic inputs can exhibit a variety of temporal relationships. A common motif is feedforward inhibition, in which an increase (decrease) in excitatory input precedes a corresponding increase (decrease) in inhibitory input. The delay of inhibitory input relative to excitatory input originates from an extra synapse in the circuit shaping inhibitory input. Another common motif is push-pull or "crossover" inhibition, in which increases (decreases) in excitatory input occur together with decreases (increases) in inhibitory input. Primate On midget ganglion cells receive primarily feedforward inhibition and On parasol cells receive primarily crossover inhibition; this difference provides an opportunity to study how each motif shapes the light responses of cell types that play a key role in visual perception. For full-field stimuli, feedforward inhibition abbreviated and attenuated responses of On midget cells, while crossover inhibition, though plentiful, had surprisingly little impact on the responses of On parasol cells. Spatially structured stimuli, however, could cause excitatory and inhibitory inputs to On parasol cells to increase together, adopting a temporal relation very much like that for feedforward inhibition. In this case, inhibitory inputs substantially abbreviated a cell's spike output. Thus inhibitory input shapes the temporal stimulus selectivity of both midget and parasol ganglion cells, but its impact on responses of parasol cells depends strongly on the spatial structure of the light inputs.

A Systematic Review of the Efficacy of Bioactive Compounds in Cardiovascular Disease: Phenolic Compounds

PubMed Central

Rangel-Huerta, Oscar D.; Pastor-Villaescusa, Belen; Aguilera, Concepcion M.; Gil, Angel

2015-01-01

The prevalence of cardiovascular diseases (CVD) is rising and is the prime cause of death in all developed countries. Bioactive compounds (BAC) can have a role in CVD prevention and treatment. The aim of this work was to examine the scientific evidence supporting phenolic BAC efficacy in CVD prevention and treatment by a systematic review. Databases utilized were Medline, LILACS and EMBASE, and all randomized controlled trials (RCTs) with prospective, parallel or crossover designs in humans in which the effects of BAC were compared with that of placebo/control were included. Vascular homeostasis, blood pressure, endothelial function, oxidative stress and inflammatory biomarkers were considered as primary outcomes. Cohort, ecological or case-control studies were not included. We selected 72 articles and verified their quality based on the Scottish Intercollegiate Guidelines Network, establishing diverse quality levels of scientific evidence according to two features: the design and bias risk of a study. Moreover, a grade of recommendation was included, depending on evidence strength of antecedents. Evidence shows that certain polyphenols, such as flavonols can be helpful in decreasing CVD risk factors. However, further rigorous evidence is necessary to support the BAC effect on CVD prevention and treatment. PMID:26132993

Halogenated Alkyltetrazoles for the Rational Design of FeII Spin-Crossover Materials: Fine-Tuning of the Ligand Size.

PubMed

Müller, Danny; Knoll, Christian; Seifried, Marco; Welch, Jan M; Giester, Gerald; Reissner, Michael; Weinberger, Peter

2018-04-06

1-(3-Halopropyl)-1H-tetrazoles and their corresponding Fe II spin-crossover complexes have been investigated in a combined experimental and theoretical study. Halogen substitution was found to positively influence the spin transition, shifting the transition temperature about 70 K towards room temperature. Halogens located at the ω position were found to be too far away from the coordinating tetrazole moiety to have an electronic impact on the spin transition. The subtle variation of the steric demand of the ligand in a highly comparable series was found to have a comparatively large impact on the spin-transition behavior, which highlights the sensitivity of the effect to subtle structural changes. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Impact of the Cognitive-Functional (Cog-Fun) Intervention on Executive Functions and Participation Among Children With Attention Deficit Hyperactivity Disorder: A Randomized Controlled Trial.

PubMed

Hahn-Markowitz, Jeri; Berger, Itai; Manor, Iris; Maeir, Adina

We examined the effect of the Cognitive-Functional (Cog-Fun) occupational therapy intervention on executive functions and participation among children with attention deficit hyperactivity disorder (ADHD). We used a randomized, controlled study with a crossover design. One hundred and seven children age 7-10 yr diagnosed with ADHD were allocated to treatment or wait-list control group. The control group received treatment after a 3-mo wait. Outcome measures included the Behavior Rating Inventory of Executive Function (BRIEF) and the Canadian Occupational Performance Measure (COPM). Significant improvements were found on both the BRIEF and COPM after intervention with large treatment effects. Before crossover, significant Time × Group interactions were found on the BRIEF. This study supports the effectiveness of the Cog-Fun intervention in improving executive functions and participation among children with ADHD. Copyright © 2017 by the American Occupational Therapy Association, Inc.

Dimensional crossover of the charge density wave transition in thin exfoliated VSe2

NASA Astrophysics Data System (ADS)

Pásztor, Árpád; Scarfato, Alessandro; Barreteau, Céline; Giannini, Enrico; Renner, Christoph

2017-12-01

Isolating single unit-cell thin layers from the bulk matrix of layered compounds offers tremendous opportunities to design novel functional electronic materials. However, a comprehensive thickness dependence study is paramount to harness the electronic properties of such atomic foils and their stacking into synthetic heterostructures. Here we show that a dimensional crossover and quantum confinement with reducing thickness result in a striking non-monotonic evolution of the charge density wave transition temperature in VSe2. Our conclusion is drawn from a direct derivation of the local order parameter and transition temperature from the real space charge modulation amplitude imaged by scanning tunnelling microscopy. This study lifts the disagreement of previous independent transport measurements. We find that thickness can be a non-trivial tuning parameter and demonstrate the importance of considering a finite thickness range to accurately characterize its influence.

Till receipts--a new approach for investigating outbreaks? Evaluation during a large Salmonella Enteritidis phage type 14b outbreak in a North West London takeaway restaurant, September 2009.

PubMed

Zenner, D; Zoellner, J; Charlett, A; Marmairis, W; Lane, C; Chow, J Y

2014-07-10

Selecting suitable controls for outbreak investigations is often difficult and if done inappropriately will lead to biased inferences. Till receipts and other sales records are frequently available on food premises, but their applicability has not been fully explored. Using data from an investigation into a Salmonella outbreak affecting 66 individuals exposed in a London takeaway restaurant, this study aimed to evaluate the use of till receipts to assess associations between sales and illness. Cases identified through local case-finding were subjected to a standardised exposure questionnaire. Till receipts over the time period when cases arose were analysed. Estimated food exposures from sales were compared to case reported exposures and till receipts analysis showed strong association between illness and consumption of rotisserie chicken (odds ratio (OR): 2.75; confidence interval (CI): 1.7-4.5). Chicken sales immediately prior to food consumption for cases were compared to two control periods in an ecological case-crossover design. On average there was an estimated increase of 3.7 (CI: 2.2-5.2) extra chickens sold in the hour immediately prior to the consumption in the cases (p<0.0001) and the risk of becoming ill at busy times increased by 5% with each additional chicken quarter sold per hour (OR: 1.05; CI: 1.03-1.08). Microbiological and environmental investigations revealed Salmonella Enteritidis phage type (PT)14b in all available cases' stool samples, two environmental samples and leftover chicken from the takeaway. The feasibility of this novel approach to obtain exposure information in the population at risk has been demonstrated, and its limitations are discussed. Further validation is required, comparing results with those in a concurrent classic case-control study.

Pulsed Dose Delivery of Oxygen in Mechanically Ventilated Pigs with Acute Lung Injury

DTIC Science & Technology

2013-03-01

collapse or arrhythmia were encountered after administration of oleic acid, chest compressions, electrical defibrillation , and epinephrine (0.1-1 mg/kg...endotracheal tube to continuously measure the oxygen content of the gas in the circuit. We designed the study as a crossover trial, so each animal served as... designed to prove that a pulsed dose delivery system would be a better method of oxygen delivery, it is interesting to note that pulsed dose delivery did

Placebo Response in Repetitive Transcranial Magnetic Stimulation Trials of Treatment of Auditory Hallucinations in Schizophrenia: A Meta-Analysis

PubMed Central

Dollfus, Sonia; Lecardeur, Laurent; Morello, Rémy; Etard, Olivier

2016-01-01

Several meta-analyses have assessed the response of patients with schizophrenia with auditory verbal hallucinations (AVH) to treatment with repetitive transcranial magnetic stimulation (rTMS); however, the placebo response has never been explored. Typically observed in a therapeutic trial, the placebo effect may have a major influence on the effectiveness of rTMS. The purpose of this meta-analysis is to evaluate the magnitude of the placebo effect observed in controlled studies of rTMS treatment of AVH, and to determine factors that can impact the magnitude of this placebo effect, such as study design considerations and the type of sham used. The study included twenty-one articles concerning 303 patients treated by sham rTMS. A meta-analytic method was applied to obtain a combined, weighted effect size, Hedges’s g. The mean weighted effect size of the placebo effect across these 21 studies was 0.29 (P < .001). Comparison of the parallel and crossover studies revealed distinct results for each study design; placebo has a significant effect size in the 13 parallel studies (g = 0.44, P < 10−4), but not in the 8 crossover studies (g = 0.06, P = .52). In meta-analysis of the 13 parallel studies, the 45° position coil showed the highest effect size. Our results demonstrate that placebo effect should be considered a major source of bias in the assessment of rTMS efficacy. These results fundamentally inform the design of further controlled studies, particularly with respect to studies of rTMS treatment in psychiatry. PMID:26089351

Randomized crossover clinical trial of real and sham peripheral prism glasses for hemianopia

PubMed Central

Bowers, Alex R.; Keeney, Karen; Peli, Eli

2013-01-01

Objective To evaluate the efficacy of real relative to sham peripheral prism glasses for patients with complete homonymous hemianopia and without visual neglect. Methods Patients recruited at 13 clinics were allocated by minimization into a double-masked, crossover trial with two groups. One group received real (57Δ) oblique and sham (≤ 5Δ) horizontal prisms; the other received real horizontal and sham oblique, in counterbalanced order. A masked data collector at each clinic administered questionnaires after each 4-week crossover period. Main outcome measure The primary outcome was the overall difference, across the two periods of the crossover, between the proportion of participants who wanted to continue with (said “yes” to) real prisms and the proportion who said yes to sham prisms. The secondary outcome was the difference in perceived mobility improvement between real and sham prisms. Results Of 73 patients randomized, 61 completed the crossover. A significantly higher proportion said yes to real than sham prisms (64% vs. 36%; odds ratio 5.3, 95% CI 1.8 to 21.0). Participants who continued wear after 6 months reported greater improvement in mobility with real than sham prisms at crossover end (p=0.002); participants who discontinued wear reported no difference. Conclusion Real peripheral prism glasses were more helpful for obstacle avoidance when walking than sham glasses, with no differences between the horizontal and oblique designs. Applications to clinical practice Peripheral prism glasses provide a simple and inexpensive mobility rehabilitation intervention for hemianopia. PMID:24201760

Tramadol use and the risk of hospitalization for hypoglycemia in patients with noncancer pain.

PubMed

Fournier, Jean-Pascal; Azoulay, Laurent; Yin, Hui; Montastruc, Jean-Louis; Suissa, Samy

2015-02-01

Tramadol is a weak opioid analgesic whose use has increased rapidly, and it has been associated with adverse events of hypoglycemia. To assess whether tramadol use, when compared with codeine use, is associated with an increased risk of hospitalization for hypoglycemia. A nested case-control analysis was conducted within the United Kingdom Clinical Practice Research Datalink linked to the Hospital Episodes Statistics database of all patients newly treated with tramadol or codeine for noncancer pain between 1998 and 2012. Cohort and case-crossover analyses were also conducted to assess consistency of the results. Cases of hospitalization for hypoglycemia were matched with up to 10 controls on age, sex, and duration of follow-up. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated comparing use of tramadol with codeine. A cohort analysis, with high-dimensional propensity score-adjusted hazard ratios (HRs) and 95% CIs, was performed comparing tramadol with codeine in the first 30 days after treatment initiation. Finally, a case-crossover analysis was also performed, in which exposure to tramadol in a 30-day risk period immediately before the hospitalization for hypoglycemia was compared with 11 consecutive 30-day control periods. Odds ratios and 95% CIs were estimated using conditional logistic regression analysis. The cohort included 334,034 patients, of whom 1105 were hospitalized for hypoglycemia during follow-up (incidence, 0.7 per 1000 per year) and matched to 11,019 controls. Compared with codeine, tramadol use was associated with an increased risk of hospitalization for hypoglycemia (OR, 1.52 [95% CI, 1.09-2.10]), particularly elevated in the first 30 days of use (OR, 2.61 [95% CI, 1.61-4.23]). This 30-day increased risk was confirmed in the cohort (HR, 3.60 [95% CI, 1.56-8.34]) and case-crossover analyses (OR, 3.80 [95% CI, 2.64-5.47]). The initiation of tramadol therapy is associated with an increased risk of hypoglycemia requiring hospitalization. Additional studies are needed to confirm this rare but potentially fatal adverse event.

Electrokinetic phenomena and dielectrophoresis in charged colloidal suspensions

NASA Astrophysics Data System (ADS)

Huang, J. P.; Karttunen, Mikko; Yu, K. W.; Dong, L.

2003-03-01

AC electrokinetic phenomena, i.e., electrorotation, dielectrophoresis and traveling wave dielectrophoresis, have gained an increasing amount of attention. This is due to their wide range of applications from cancer research to identifying and separating parasites, cell populations and viruses, and even to design of nanomotors. Despite the number of applications, there is need for a theory that treats the different aspects of electrokinetic phenomena on an equal footing starting from the general underlying physical principles. Here, we present a theoretical study of dielectrophoretic (DEP) crossover spectrum of two polarizable particles under the action of a nonuniform AC electric field. For two approaching particles, the mutual polarization interaction yields a change in their respective dipole moments, and hence, in the DEP crossover spectrum. We use the multiple image method to study the induced polarization effects and using spectral representation theory, an analytic expression for the DEP force is derived. Our results shows that the mutual polarization effects can change the crossover frequency at which the DEP force changes sign. The results are in agreement with recent experimental observations. Importantly, this approach goes beyond the standard theory and helps to clarify the important question of the underlying polarization mechanisms. The extension to dense systems and relation to electrorotation is discussed.

An approach for sample size determination of average bioequivalence based on interval estimation.

PubMed

Chiang, Chieh; Hsiao, Chin-Fu

2017-03-30

In 1992, the US Food and Drug Administration declared that two drugs demonstrate average bioequivalence (ABE) if the log-transformed mean difference of pharmacokinetic responses lies in (-0.223, 0.223). The most widely used approach for assessing ABE is the two one-sided tests procedure. More specifically, ABE is concluded when a 100(1 - 2α) % confidence interval for mean difference falls within (-0.223, 0.223). As known, bioequivalent studies are usually conducted by crossover design. However, in the case that the half-life of a drug is long, a parallel design for the bioequivalent study may be preferred. In this study, a two-sided interval estimation - such as Satterthwaite's, Cochran-Cox's, or Howe's approximations - is used for assessing parallel ABE. We show that the asymptotic joint distribution of the lower and upper confidence limits is bivariate normal, and thus the sample size can be calculated based on the asymptotic power so that the confidence interval falls within (-0.223, 0.223). Simulation studies also show that the proposed method achieves sufficient empirical power. A real example is provided to illustrate the proposed method. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

Effects on Occupants of Enhanced Particle Filtration in a non-problem office environment: A Double-Blind Crossover Intervention Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mendell, M.J.; Fisk, W.J.; Petersen, M.

1998-06-15

Workers in indoor environments often complain of symptoms, such as eye and nose irritation, headache, and fatigue, which improve away from work. Exposures causing such complaints, sometimes referred to as sick building syndrome, generally have not been identified. Evidence suggests these worker symptoms are related to chemical, microbiological, physical, and psychosocial exposures not well characterized by current methods. Most research in this area has involved cross-sectional studies, which are limited in their abilities to show causal connections. Experimental studies have also been conducted which, by changing one factor at a time to isolate its effects, can demonstrate benefits of anmore » environmental intervention even before exposures or mechanisms are understood. This study was prompted by evidence that particulate contaminants may be related to acute occupant symptoms and discomfort. The objective was to assess, with a double-blind, double crossover intervention design, whether improved removal of small airborne particles by enhanced central filtration would reduce symptoms and discomfort.« less

Flooding and Emergency Room Visits for Gastrointestinal Illness in Massachusetts: A Case-Crossover Study

PubMed Central

Wade, Timothy J.; Lin, Cynthia J.; Jagai, Jyotsna S.; Hilborn, Elizabeth D.

2014-01-01

Introduction Floods and other severe weather events are anticipated to increase as a result of global climate change. Floods can lead to outbreaks of gastroenteritis and other infectious diseases due to disruption of sewage and water infrastructure and impacts on sanitation and hygiene. Floods have also been indirectly associated with outbreaks through population displacement and crowding. Methods We conducted a case-crossover study to investigate the association between flooding and emergency room visits for gastrointestinal illness (ER-GI) in Massachusetts for the years 2003 through 2007. We obtained ER-GI visits from the State of Massachusetts and records of floods from the National Oceanic and Atmospheric Association’s Storm Events Database. ER-GI visits were considered exposed if a flood occurred in the town of residence within three hazard periods of the visit: 0–4 days; 5–9 days; and 10–14 days. A time-stratified bi-directional design was used for control selection, matching on day of the week with two weeks lead or lag time from the ER-GI visit. Fixed effect logistic regression models were used to estimate the risk of ER-GI visits following the flood. Results and Conclusions A total of 270,457 ER-GI visits and 129 floods occurred in Massachusetts over the study period. Across all counties, flooding was associated with an increased risk for ER-GI in the 0–4 day period after flooding (Odds Ratio: 1.08; 95% Confidence Interval: 1.03–1.12); but not the 5–9 days (Odds Ratio: 0.995; 95% Confidence Interval: 0.955–1.04) or the 10–14 days after (Odds Ratio: 0.966, 95% Confidence Interval: 0.927–1.01). Similar results were observed for different definitions of ER-GI. The effect differed across counties, suggesting local differences in the risk and impact of flooding. Statewide, across the study period, an estimated 7% of ER-GI visits in the 0–4 days after a flood event were attributable to flooding. PMID:25329916

Pharmacological treatments of cerebellar ataxia.

PubMed

Ogawa, Masafumi

2004-01-01

The confirmed pharmacological treatment of cerebellar ataxia is still lacking. In a recent preliminary trial, we showed that D-cycloserine, a partial NMDA allosteric agonist, may relieve the symptoms. In this paper, major clinical trials to relieve ataxic symptoms are reviewed. Previous studies showed some efficacy of physostigmine in ataxic patients. However, physostigmine did not improve the ataxia in a recent double-blind crossover study. The replacement therapy of the deficient cholinergic system with choline or choline derivatives was tried in patients with Friedreich's ataxia and other ataxic patients, but the result was not definitive. A levorotatory form of hydroxytryptophan (a serotonin precursor), a serotoninergic 5-HT1A agonist, a serotoninergic 5-HT3 antagonist, and a serotonin reuptake inhibitor were also used for the therapy for ataxia. In a double-blind randomized study, buspirone, a 5-HT1A agonist was active in cerebellar ataxia, but the effect is partial and not major. The effects of the studies with the other serotoninergic drugs were not consistent. The effect of sulfamethoxazole-trimethoprim therapy in spinocerebellar ataxia type3/Machado-Joseph disease (MJD) was reported, although the therapy improved spasticity or rigidity, rather than ataxia. In contrast to previous studies, sulfamethoxazole-trimethoprim therapy in MJD had no effect in a 2001 double-blind crossover study. The thyrotropin-releasing hormone, D-cycloserine, and acetazolamide for SCA6 may have some efficacy. However, a well-designed double-blind crossover trial is needed to confirm the effect.

Investigation of crossover processes in a unitized bidirectional vanadium/air redox flow battery

NASA Astrophysics Data System (ADS)

grosse Austing, Jan; Nunes Kirchner, Carolina; Komsiyska, Lidiya; Wittstock, Gunther

2016-02-01

In this paper the losses in coulombic efficiency are investigated for a vanadium/air redox flow battery (VARFB) comprising a two-layered positive electrode. Ultraviolet/visible (UV/Vis) spectroscopy is used to monitor the concentrations cV2+ and cV3+ during operation. The most likely cause for the largest part of the coulombic losses is the permeation of oxygen from the positive to the negative electrode followed by an oxidation of V2+ to V3+. The total vanadium crossover is followed by inductively coupled plasma mass spectroscopy (ICP-MS) analysis of the positive electrolyte after one VARFB cycle. During one cycle 6% of the vanadium species initially present in the negative electrolyte are transferred to the positive electrolyte, which can account at most for 20% of the coulombic losses. The diffusion coefficients of V2+ and V3+ through Nafion® 117 are determined as DV2+ ,N 117 = 9.05 ·10-6 cm2 min-1 and DV3+ ,N 117 = 4.35 ·10-6 cm2 min-1 and are used to calculate vanadium crossover due to diffusion which allows differentiation between vanadium crossover due to diffusion and migration/electroosmotic convection. In order to optimize coulombic efficiency of VARFB, membranes need to be designed with reduced oxygen permeation and vanadium crossover.

Confidence intervals for distinguishing ordinal and disordinal interactions in multiple regression.

PubMed

Lee, Sunbok; Lei, Man-Kit; Brody, Gene H

2015-06-01

Distinguishing between ordinal and disordinal interaction in multiple regression is useful in testing many interesting theoretical hypotheses. Because the distinction is made based on the location of a crossover point of 2 simple regression lines, confidence intervals of the crossover point can be used to distinguish ordinal and disordinal interactions. This study examined 2 factors that need to be considered in constructing confidence intervals of the crossover point: (a) the assumption about the sampling distribution of the crossover point, and (b) the possibility of abnormally wide confidence intervals for the crossover point. A Monte Carlo simulation study was conducted to compare 6 different methods for constructing confidence intervals of the crossover point in terms of the coverage rate, the proportion of true values that fall to the left or right of the confidence intervals, and the average width of the confidence intervals. The methods include the reparameterization, delta, Fieller, basic bootstrap, percentile bootstrap, and bias-corrected accelerated bootstrap methods. The results of our Monte Carlo simulation study suggest that statistical inference using confidence intervals to distinguish ordinal and disordinal interaction requires sample sizes more than 500 to be able to provide sufficiently narrow confidence intervals to identify the location of the crossover point. (c) 2015 APA, all rights reserved).

Sensory Adapted Dental Environments to Enhance Oral Care for Children with Autism Spectrum Disorders: A Randomized Controlled Pilot Study

ERIC Educational Resources Information Center

Cermak, Sharon A.; Stein Duker, Leah I.; Williams, Marian E.; Dawson, Michael E.; Lane, Christianne J.; Polido, José C.

2015-01-01

This pilot and feasibility study examined the impact of a sensory adapted dental environment (SADE) to reduce distress, sensory discomfort, and perception of pain during oral prophylaxis for children with autism spectrum disorder (ASD). Participants were 44 children ages 6-12 (n = 22 typical, n = 22 ASD). In an experimental crossover design, each…

The acute effect of pleasurable music on craving for alcohol: A pilot crossover study.

PubMed

Mathis, Walter S; Han, Xiaotong

2017-07-01

Chronic administration of drugs of abuse leads to a dopamine deficient state in the mesolimbic system, causing dysphoria in abstinence and contributing to craving and return to use. Recent functional imaging studies have shown that listening to personally pleasing music activates the mesolimbic reward system in a fashion similar to drugs of abuse. It has been proposed that such activation could ameliorate the dysphoria and craving of the hypodopaminergic state. The present study sought to evaluate the efficacy of listening to personally pleasing or moving music on reducing craving in abstinent alcoholics using a single-blind, within-subject randomized block design, with three randomly determined presentations of each condition. Twelve participants with Alcohol Use Disorder on a residential substance rehabilitation unit reported their level of craving with a Visual Analog Scale before and after listening to either the participant-selected song or white noise. Using a mixed model to analyze the crossover design, the music intervention was found to have a statistically significant advantage in craving reduction compared to the noise control. Our results indicate that personally pleasing music might have a role in augmenting substance use disorder treatment via craving reduction. Further study is warranted to elucidate factors which predict the most robust response from this intervention. Copyright © 2017 Elsevier Ltd. All rights reserved.

2-Methacryloyloxyethyl phosphorylcholine (MPC)-polymer suppresses an increase of oral bacteria: a single-blind, crossover clinical trial.

PubMed

Fujiwara, Natsumi; Yumoto, Hiromichi; Miyamoto, Koji; Hirota, Katsuhiko; Nakae, Hiromi; Tanaka, Saya; Murakami, Keiji; Kudo, Yasusei; Ozaki, Kazumi; Miyake, Yoichiro

2018-05-16

The biocompatible 2-methacryloyloxyethyl phosphorylcholine (MPC)-polymers, which mimic a biomembrane, reduce protein adsorption and bacterial adhesion and inhibit cell attachment. The aim of this study is to clarify whether MPC-polymer can suppress the bacterial adherence in oral cavity by a crossover design. We also investigated the number of Fusobacterium nucleatum, which is the key bacterium forming dental plaque, in clinical samples. This study was a randomized, placebo-controlled, single-blind, crossover study, with two treatment periods separated by a 2-week washout period. We conducted clinical trial with 20 healthy subjects to evaluate the effect of 5% MPC-polymer mouthwash after 5 h on oral microflora. PBS was used as a control. The bacterial number in the gargling sample before and after intervention was counted by an electronic bacterial counter and a culture method. DNA amounts of total bacteria and F. nucleatum were examined by q-PCR. The numbers of total bacteria and oral streptcocci after 5 h of 5% MPC-polymer treatment significantly decreased, compared to the control group. Moreover, the DNA amounts of total bacteria and F. nucleatum significantly decreased by 5% MPC-polymer mouthwash. We suggest that MPC-polymer coating in the oral cavity may suppress the oral bacterial adherence. MPC-polymer can be a potent compound for the control of oral microflora to prevent oral infection.

Benefits and challenges of using the cohort multiple randomised controlled trial design for testing an intervention for depression.

PubMed

Viksveen, Petter; Relton, Clare; Nicholl, Jon

2017-07-06

Trials which test the effectiveness of interventions compared with the status quo frequently encounter challenges. The cohort multiple randomised controlled trial (cmRCT) design is an innovative approach to the design and conduct of pragmatic trials which seeks to address some of these challenges. In this article, we report our experiences with the first completed randomised controlled trial (RCT) using the cmRCT design. This trial-the Depression in South Yorkshire (DEPSY) trial-involved comparison of treatment as usual (TAU) with TAU plus the offer of an intervention for people with self-reported long-term moderate to severe depression. In the trial, we used an existing large population-based cohort: the Yorkshire Health Study. We discuss our experiences with recruitment, attrition, crossover, data analysis, generalisability of results, and cost. The main challenges in using the cmRCT design were the high crossover to the control group and the lower questionnaire response rate among patients who refused the offer of treatment. However, the design did help facilitate efficient and complete recruitment of the trial population as well as analysable data that were generalisable to the population of interest. Attrition rates were also smaller than those reported in other depression trials. This first completed full trial using the cmRCT design testing an intervention for self-reported depression was associated with a number of important benefits. Further research is required to compare the acceptability and cost effectiveness of standard pragmatic RCT design with the cmRCT design. ISRCTN registry: ISRCTN02484593 . Registered on 7 Jan 2013.

RELIABILITY AND VALIDITY OF FUNCTIONAL PERFORMANCE TESTS IN DANCERS WITH HIP DYSFUNCTION

PubMed Central

Carcia, Christopher R.; Clemente, F. Richard; Phelps, Amy L.; Martin, RobRoy L.

2013-01-01

Study Design: Quasi-experimental, repeated measures. Purpose/Background: Functional performance tests that identify hip joint impairments and assess the effect of intervention have not been adequately described for dancers. The purpose of this study was to examine the reliability and validity of hop and balance tests among a group of dancers with musculoskeletal pain in the hip region. Methods: Nineteen female dancers (age: 18.90±1.11 years; height: 164.85±6.95 cm; weight: 60.37±8.29 kg) with unilateral hip pain were assessed utilizing the cross-over reach, medial triple hop, lateral triple hop, and cross-over hop tests on two occasions, 2 days apart. Test-retest reliability and comparisons between the involved and uninvolved side for each respective test were determined. Results: Intra-class correlation coefficients for the functional performance tests ranged from 0.89-0.96. The cross-over reach test had a SEM of 2.79 cm and a MDC of 7.73 cm. The medial and lateral triple hop tests had SEM values of 7.51 cm and 8.17 cm, and MDC values of 20.81 cm and 22.62 cm, respectively. The SEM was 0.15 seconds and the MDC was 0.42 seconds for the cross-over hop test. Performance on the medial triple hop test was significantly less on the involved side (370.21±38.26 cm) compared to the uninvolved side (388.05±41.49 cm); t(18) = −4.33, p<0.01. The side-to-side comparisons of the cross-over reach test (involved mean=61.68±10.9 cm; uninvolved mean=61.69±8.63 cm); t(18) = −0.004, p=0.99, lateral triple hop test (involved mean=306.92±35.79 cm; uninvolved mean=310.68±24.49 cm); t(18) = −0.55, p=0.59, and cross-over hop test (involved mean=2.49±0.34 seconds; uninvolved mean= 2.61±0.42 seconds; t(18) = −1.84, p=0.08) were not statistically different between sides. Conclusion: The functional performance tests used in this study can be reliably performed on dancers with unilateral hip pain. The medial triple hop test was the only functional performance test with evidence of validity in side-to-side comparisons. These results suggest that the medial triple hop test may be a reliable and valid functional performance test to assess impairments related to hip pain among dancers. Level of Evidence: 3b. Non-consecutive cohort study PMID:24175123

University Students' Attainment and Perceptions of Computer Delivered Assessment; A Comparison between Computer-Based and Traditional Tests in a "High-Stakes" Examination

ERIC Educational Resources Information Center

Escudier, M. P.; Newton, T. J.; Cox, M. J.; Reynolds, P. A.; Odell, E. W.

2011-01-01

This study compared higher education dental undergraduate student performance in online assessments with performance in traditional paper-based tests and investigated students' perceptions of the fairness and acceptability of online tests, and showed performance to be comparable. The project design involved two parallel cross-over trials, one in…

Threshold Levels of Infant and Under-Five Mortality for Crossover between Life Expectancies at Ages Zero, One and Five in India: A Decomposition Analysis.

PubMed

Dubey, Manisha; Ram, Usha; Ram, Faujdar

2015-01-01

Under the prevailing conditions of imbalanced life table and historic gender discrimination in India, our study examines crossover between life expectancies at ages zero, one and five years for India and quantifies the relative share of infant and under-five mortality towards this crossover. We estimate threshold levels of infant and under-five mortality required for crossover using age specific death rates during 1981-2009 for 16 Indian states by sex (comprising of India's 90% population in 2011). Kitagawa decomposition equations were used to analyse relative share of infant and under-five mortality towards crossover. India experienced crossover between life expectancies at ages zero and five in 2004 for menand in 2009 for women; eleven and nine Indian states have experienced this crossover for men and women, respectively. Men usually experienced crossover four years earlier than the women. Improvements in mortality below ages five have mostly contributed towards this crossover. Life expectancy at age one exceeds that at age zero for both men and women in India except for Kerala (the only state to experience this crossover in 2000 for men and 1999 for women). For India, using life expectancy at age zero and under-five mortality rate together may be more meaningful to measure overall health of its people until the crossover. Delayed crossover for women, despite higher life expectancy at birth than for men reiterates that Indian women are still disadvantaged and hence use of life expectancies at ages zero, one and five become important for India. Greater programmatic efforts to control leading causes of death during the first month and 1-59 months in high child mortality areas can help India to attain this crossover early.

Modeling of ion transport through a porous separator in vanadium redox flow batteries

NASA Astrophysics Data System (ADS)

Zhou, X. L.; Zhao, T. S.; An, L.; Zeng, Y. K.; Wei, L.

2016-09-01

In this work, we develop a two-dimensional, transient model to investigate the mechanisms of ion-transport through a porous separator in VRFBs and their effects on battery performance. Commercial-available separators with pore sizes of around 45 nm are particularly investigated and effects of key separator design parameters and operation modes are explored. We reveal that: i) the transport mechanism of vanadium-ion crossover through available separators is predominated by convection; ii) reducing the pore size below 15 nm effectively minimizes the convection-driven vanadium-ion crossover, while further reduction in migration- and diffusion-driven vanadium-ion crossover can be achieved only when the pore size is reduced to the level close to the sizes of vanadium ions; and iii) operation modes that can affect the pressure at the separator/electrode interface, such as the electrolyte flow rate, exert a significant influence on the vanadium-ion crossover rate through the available separators, indicating that it is critically important to equalize the pressure on each half-cell of a power pack in practical applications.

Structured Cable for High-Current Coils of Tokamaks

NASA Astrophysics Data System (ADS)

Benson, Christopher; McIntyre, Peter; Sattarov, Akhdiyor; Mann, Thomas

2011-10-01

The 45 kA superconducting cable for the ITER central solenoid coil has yielded questionable results in two recent tests. In both cases the cable Tc increased after cycling only a fraction of the design life, indicating degradation due to fatigue and fracture among the superconducting strands. The Accelerator Research Lab at Texas A&M University is developing a design for a Nb3Sn structured cable suitable for such tokamak coils. The superconductor is configured in 6 sub-cables, and each subcable is supported within a channel of a central support structure within a high-strength armor sheath. The structured cable addresses two issues that are thought to compromise opposition at high current. The strands are supported without cross-overs (which produce stress concentration); and armor sheath and core structure bypass stress through the coil and among subcables so that the stress within each subcable is only what is produced directly upon it. Details of the design and plans for development will be presented.

A randomized, single-blind cross-over design evaluating the effectiveness of an individually defined, targeted physical therapy approach in treatment of children with cerebral palsy.

PubMed

Franki, Inge; Van den Broeck, Christine; De Cat, Josse; Tijhuis, Wieke; Molenaers, Guy; Vanderstraeten, Guy; Desloovere, Kaat

2014-10-01

A pilot study to compare the effectiveness of an individual therapy program with the effects of a general physical therapy program. A randomized, single-blind cross-over design. Ten ambulant children with bilateral spastic cerebral palsy, age four to nine years. Participants were randomly assigned into a ten-week individually defined, targeted or a general program, followed by a cross-over. Evaluation was performed using the Gross Motor Function Measure-88 and three-dimensional gait analysis. General outcome parameters were Gross Motor Function Measure-88 scores, time and distance parameters, gait profile score and movement analysis profiles. Individual goal achievement was evaluated using z-scores for gait parameters and Goal Attainment Scale for gross motor function. No significant changes were observed regarding gross motor function. Only after individualized therapy, step- and stride-length increased significantly (p = 0.022; p = 0.017). Change in step-length was higher after the individualized program (p = 0.045). Within-group effects were found for the pelvis in transversal plane after the individualized program (p = 0.047) and in coronal plane after the general program (p = 0.047). Between-program differences were found for changes in the knee in sagittal plane, in the advantage of the individual program (p = 0.047). A median difference in z-score of 0.279 and 0.419 was measured after the general and individualized program, respectively. Functional goal attainment was higher after the individual therapy program compared with the general program (48 to 43.5). The results indicate slightly favorable effects towards the individualized program. To detect clinically significant changes, future studies require a minimal sample size of 72 to 90 participants. © The Author(s) 2014.

The effects of particulate matter sources on daily mortality: a case-crossover study of Barcelona, Spain.

PubMed

Ostro, Bart; Tobias, Aurelio; Querol, Xavier; Alastuey, Andrés; Amato, Fulvio; Pey, Jorge; Pérez, Noemí; Sunyer, Jordi

2011-12-01

Dozens of studies link acute exposure to particulate matter (PM) air pollution with premature mortality and morbidity, but questions remain about which species and sources in the vast PM mixture are responsible for the observed health effects. Although a few studies exist on the effects of species and sources in U.S. cities, European cities-which have a higher proportion of diesel engines and denser urban populations-have not been well characterized. Information on the effects of specific sources could aid in targeting pollution control and in articulating the biological mechanisms of PM. Our study examined the effects of various PM sources on daily mortality for 2003 through 2007 in Barcelona, a densely populated city in the northeast corner of Spain. Source apportionment for PM ≤ 2.5 μm and ≤ 10 µm in aerodynamic diameter (PM2.5 and PM10) using positive matrix factorization identified eight different factors. Case-crossover regression analysis was used to estimate the effects of each factor. Several sources of PM2.5, including vehicle exhaust, fuel oil combustion, secondary nitrate/organics, minerals, secondary sulfate/organics, and road dust, had statistically significant associations (p < 0.05) with all-cause and cardiovascular mortality. Also, in some cases relative risks for a respective interquartile range increase in concentration were higher for specific sources than for total PM2.5 mass. These results along with those from our multisource models suggest that traffic, sulfate from shipping and long-range transport, and construction dust are important contributors to the adverse health effects linked to PM.

The Effect of Reflective Activities on Reflective Thinking Ability in an Undergraduate Pharmacy Curriculum.

PubMed

Tsingos-Lucas, Cherie; Bosnic-Anticevich, Sinthia; Schneider, Carl R; Smith, Lorraine

2016-05-25

Objective. To determine the effectiveness of integrating reflective practice activities into a second-year undergraduate pharmacy curriculum and their impact on reflective thinking ability. Design. A cross-over design with repeated measures was employed. Newly developed reflective modules based on real hospital and community pharmacy cases were integrated into the second-year pharmacy practice curriculum. A novel strategy, the Reflective Ability Clinical Assessment (RACA), was introduced to enhance self- and peer reflection. Assessment. Student responses (n=214) to the adapted Kember et al(1) Reflective Thinking Questionnaire (RTQ) were compared before and after reflective activities were undertaken. Significant improvement in three indicators of reflective thinking was shown after students engaged in reflective activities. Conclusion. Integration of reflective activities into a pharmacy curriculum increased the reflective thinking capacity of students. Enhancing reflective thinking ability may help students make better informed decisions and clinical judgments, thus improving future practice.

The Effect of Reflective Activities on Reflective Thinking Ability in an Undergraduate Pharmacy Curriculum

PubMed Central

Bosnic-Anticevich, Sinthia; Schneider, Carl R.; Smith, Lorraine

2016-01-01

Objective. To determine the effectiveness of integrating reflective practice activities into a second-year undergraduate pharmacy curriculum and their impact on reflective thinking ability. Design. A cross-over design with repeated measures was employed. Newly developed reflective modules based on real hospital and community pharmacy cases were integrated into the second-year pharmacy practice curriculum. A novel strategy, the Reflective Ability Clinical Assessment (RACA), was introduced to enhance self- and peer reflection. Assessment. Student responses (n=214) to the adapted Kember et al1 Reflective Thinking Questionnaire (RTQ) were compared before and after reflective activities were undertaken. Significant improvement in three indicators of reflective thinking was shown after students engaged in reflective activities. Conclusion. Integration of reflective activities into a pharmacy curriculum increased the reflective thinking capacity of students. Enhancing reflective thinking ability may help students make better informed decisions and clinical judgments, thus improving future practice. PMID:27293232

Crossover Patterning by the Beam-Film Model: Analysis and Implications

PubMed Central

Zhang, Liangran; Liang, Zhangyi; Hutchinson, John; Kleckner, Nancy

2014-01-01

Crossing-over is a central feature of meiosis. Meiotic crossover (CO) sites are spatially patterned along chromosomes. CO-designation at one position disfavors subsequent CO-designation(s) nearby, as described by the classical phenomenon of CO interference. If multiple designations occur, COs tend to be evenly spaced. We have previously proposed a mechanical model by which CO patterning could occur. The central feature of a mechanical mechanism is that communication along the chromosomes, as required for CO interference, can occur by redistribution of mechanical stress. Here we further explore the nature of the beam-film model, its ability to quantitatively explain CO patterns in detail in several organisms, and its implications for three important patterning-related phenomena: CO homeostasis, the fact that the level of zero-CO bivalents can be low (the “obligatory CO”), and the occurrence of non-interfering COs. Relationships to other models are discussed. PMID:24497834

Methodological considerations in a pilot study on the effects of a berry enriched smoothie on children’s performance in school

PubMed Central

Rosander, Ulla; Rumpunen, Kimmo; Olsson, Viktoria; Åström, Mikael; Rosander, Pia; Wendin, Karin

2017-01-01

ABSTRACT Berries contain bioactive compounds that may affect children’s cognitive function positively, while hunger and thirst during lessons before lunch affect academic performance negatively. This pilot study addresses methodological challenges in studying if a berry smoothie, offered to schoolchildren as a mid-morning beverage, affects academic performance. The objective was to investigate if a cross-over design can be used to study these effects in a school setting. Therefore, in order to investigate assay sensitivity, 236 Swedish children aged 10–12 years were administered either a berry smoothie (active) or a fruit-based control beverage after their mid-morning break. Both beverages provided 5% of child daily energy intake. In total, 91% of participants completed the study. Academic performance was assessed using the d2 test of attention. Statistical analyses were performed using the Wilcoxon signed rank test in StatXact v 10.3. The results showed that the children consumed less of the active berry smoothie than the control (154 g vs. 246 g). Both beverages increased attention span and concentration significantly (p = 0.000). However, as there was no significant difference (p = 0.938) in the magnitude of this effect between the active and control beverages, the assay sensitivity of the study design was not proven. The effect of the beverages on academic performance was attributed the supplementation of water and energy. Despite careful design, the active smoothie was less accepted than the control. This could be explained by un-familiar sensory characteristics and peer influence, stressing the importance of sensory similarity and challenges to perform a study in school settings. The employed cross-over design did not reveal any effects of bioactive compound consumption on academic performance. In future studies, the experimental set up should be modified or replaced by e.g. the parallel study design, in order to provide conclusive results. PMID:29230155

Methodological considerations in a pilot study on the effects of a berry enriched smoothie on children's performance in school.

PubMed

Rosander, Ulla; Rumpunen, Kimmo; Olsson, Viktoria; Åström, Mikael; Rosander, Pia; Wendin, Karin

2017-01-01

Berries contain bioactive compounds that may affect children's cognitive function positively, while hunger and thirst during lessons before lunch affect academic performance negatively. This pilot study addresses methodological challenges in studying if a berry smoothie, offered to schoolchildren as a mid-morning beverage, affects academic performance. The objective was to investigate if a cross-over design can be used to study these effects in a school setting. Therefore, in order to investigate assay sensitivity, 236 Swedish children aged 10-12 years were administered either a berry smoothie (active) or a fruit-based control beverage after their mid-morning break. Both beverages provided 5% of child daily energy intake. In total, 91% of participants completed the study. Academic performance was assessed using the d2 test of attention. Statistical analyses were performed using the Wilcoxon signed rank test in StatXact v 10.3. The results showed that the children consumed less of the active berry smoothie than the control (154 g vs. 246 g). Both beverages increased attention span and concentration significantly (p = 0.000). However, as there was no significant difference (p = 0.938) in the magnitude of this effect between the active and control beverages, the assay sensitivity of the study design was not proven. The effect of the beverages on academic performance was attributed the supplementation of water and energy. Despite careful design, the active smoothie was less accepted than the control. This could be explained by un-familiar sensory characteristics and peer influence, stressing the importance of sensory similarity and challenges to perform a study in school settings. The employed cross-over design did not reveal any effects of bioactive compound consumption on academic performance. In future studies, the experimental set up should be modified or replaced by e.g. the parallel study design, in order to provide conclusive results.

Stepped wedge designs: insights from a design of experiments perspective.

PubMed

Matthews, J N S; Forbes, A B

2017-10-30

Stepped wedge designs (SWDs) have received considerable attention recently, as they are potentially a useful way to assess new treatments in areas such as health services implementation. Because allocation is usually by cluster, SWDs are often viewed as a form of cluster-randomized trial. However, since the treatment within a cluster changes during the course of the study, they can also be viewed as a form of crossover design. This article explores SWDs from the perspective of crossover trials and designed experiments more generally. We show that the treatment effect estimator in a linear mixed effects model can be decomposed into a weighted mean of the estimators obtained from (1) regarding an SWD as a conventional row-column design and (2) a so-called vertical analysis, which is a row-column design with row effects omitted. This provides a precise representation of "horizontal" and "vertical" comparisons, respectively, which to date have appeared without formal description in the literature. This decomposition displays a sometimes surprising way the analysis corrects for the partial confounding between time and treatment effects. The approach also permits the quantification of the loss of efficiency caused by mis-specifying the correlation parameter in the mixed-effects model. Optimal extensions of the vertical analysis are obtained, and these are shown to be highly inefficient for values of the within-cluster dependence that are likely to be encountered in practice. Some recently described extensions to the classic SWD incorporating multiple treatments are also compared using the experimental design framework. Copyright © 2017 John Wiley & Sons, Ltd.

Combinatorial optimization problem solution based on improved genetic algorithm

NASA Astrophysics Data System (ADS)

Zhang, Peng

2017-08-01

Traveling salesman problem (TSP) is a classic combinatorial optimization problem. It is a simplified form of many complex problems. In the process of study and research, it is understood that the parameters that affect the performance of genetic algorithm mainly include the quality of initial population, the population size, and crossover probability and mutation probability values. As a result, an improved genetic algorithm for solving TSP problems is put forward. The population is graded according to individual similarity, and different operations are performed to different levels of individuals. In addition, elitist retention strategy is adopted at each level, and the crossover operator and mutation operator are improved. Several experiments are designed to verify the feasibility of the algorithm. Through the experimental results analysis, it is proved that the improved algorithm can improve the accuracy and efficiency of the solution.

Computer-aided design of DNA origami structures.

PubMed

Selnihhin, Denis; Andersen, Ebbe Sloth

2015-01-01

The DNA origami method enables the creation of complex nanoscale objects that can be used to organize molecular components and to function as reconfigurable mechanical devices. Of relevance to synthetic biology, DNA origami structures can be delivered to cells where they can perform complicated sense-and-act tasks, and can be used as scaffolds to organize enzymes for enhanced synthesis. The design of DNA origami structures is a complicated matter and is most efficiently done using dedicated software packages. This chapter describes a procedure for designing DNA origami structures using a combination of state-of-the-art software tools. First, we introduce the basic method for calculating crossover positions between DNA helices and the standard crossover patterns for flat, square, and honeycomb DNA origami lattices. Second, we provide a step-by-step tutorial for the design of a simple DNA origami biosensor device, from schematic idea to blueprint creation and to 3D modeling and animation, and explain how careful modeling can facilitate later experimentation in the laboratory.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kung, Y. F.; Bazin, C.; Wohlfeld, K.

Using determinant quantum Monte Carlo (DQMC) simulations, we systematically study the doping dependence of the crossover from one to two dimensions and its impact on the magnetic properties of the Hubbard model. A square lattice of chains is used, in which the dimensionality can be tuned by varying the interchain coupling t ⊥. The dynamical spin structure factor and static quantities, such as the static spin susceptibility and nearest-neighbor spin correlation function, are characterized in the one- and two-dimensional limits as a benchmark. When the dimensionality is tuned between these limits, the magnetic properties, while evolving smoothly from one tomore » two dimensions, drastically change regardless of the doping level. This suggests that the spin excitations in the two-dimensional Hubbard model, even in the heavily doped case, cannot be explained using the spinon picture known from one dimension. In conclusion, the DQMC calculations are complemented by cluster perturbation theory studies to form a more complete picture of how the crossover occurs as a function of doping and how doped holes impact magnetic order.« less

Checking distributional assumptions for pharmacokinetic summary statistics based on simulations with compartmental models.

PubMed

Shen, Meiyu; Russek-Cohen, Estelle; Slud, Eric V

2016-08-12

Bioequivalence (BE) studies are an essential part of the evaluation of generic drugs. The most common in vivo BE study design is the two-period two-treatment crossover design. AUC (area under the concentration-time curve) and Cmax (maximum concentration) are obtained from the observed concentration-time profiles for each subject from each treatment under each sequence. In the BE evaluation of pharmacokinetic crossover studies, the normality of the univariate response variable, e.g. log(AUC) 1 or log(Cmax), is often assumed in the literature without much evidence. Therefore, we investigate the distributional assumption of the normality of response variables, log(AUC) and log(Cmax), by simulating concentration-time profiles from two-stage pharmacokinetic models (commonly used in pharmacokinetic research) for a wide range of pharmacokinetic parameters and measurement error structures. Our simulations show that, under reasonable distributional assumptions on the pharmacokinetic parameters, log(AUC) has heavy tails and log(Cmax) is skewed. Sensitivity analyses are conducted to investigate how the distribution of the standardized log(AUC) (or the standardized log(Cmax)) for a large number of simulated subjects deviates from normality if distributions of errors in the pharmacokinetic model for plasma concentrations deviate from normality and if the plasma concentration can be described by different compartmental models.

Clinical Trials

MedlinePlus

... pill that has no medicine in it. Most times participants do not know which they are receiving. Other clinical trials involve a crossover design, where participants are randomly assigned to take a ...

Scaling Exponents in Financial Markets

NASA Astrophysics Data System (ADS)

Kim, Kyungsik; Kim, Cheol-Hyun; Kim, Soo Yong

2007-03-01

We study the dynamical behavior of four exchange rates in foreign exchange markets. A detrended fluctuation analysis (DFA) is applied to detect the long-range correlation embedded in the non-stationary time series. It is for our case found that there exists a persistent long-range correlation in volatilities, which implies the deviation from the efficient market hypothesis. Particularly, the crossover is shown to exist in the scaling behaviors of the volatilities.

The relationship between changes in daily air pollution and hospitalizations in Perth, Australia 1992-1998: a case-crossover study.

PubMed

Hinwood, A L; De Klerk, N; Rodriguez, C; Jacoby, P; Runnion, T; Rye, P; Landau, L; Murray, F; Feldwick, M; Spickett, J

2006-02-01

A case-crossover study was undertaken to investigate the relationship between daily air pollutant concentrations and daily hospitalizations for selected disease categories in Perth, Western Australia. Daily measurements of particles (measured by nephelometry and PM2.5), photochemical oxidants (measured as ozone), nitrogen dioxide (NO2) and carbon monoxide (CO) concentrations were obtained from 1992 to 1998 via a metropolitan network of monitoring stations. Daily PM2.5 concentrations were estimated using monitored data, modelling and interpolation. Hospital morbidity data for respiratory, cardiovascular (CVD), gastrointestinal (GI) diseases, chronic obstructive pulmonary diseases (COPD) excluding asthma; pneumonia/influenza diseases; and asthma were obtained and categorized into all ages, less than 15 years and greater than 65 years. Gastrointestinal morbidity was used as a control disease. The data were analyzed using conditional logistic regression. The results showed a small number of significant associations for daily changes in particle concentrations, nitrogen dioxide and carbon monoxide for the respiratory diseases, CODP, pneumonia, asthma and CVD hospitalizations. Changes in ozone concentrations were not significantly associated with any disease outcomes. These data provide useful information on the potential health impacts of air pollution in an airshed with very low sulphur dioxide concentrations and lower nitrogen dioxide concentrations commonly found in many other cities.

Alcohol Abuse and Suicide Attempt in Iran: A Case-Crossover Study

PubMed Central

Ghanbari, Behrooz; Malakouti, Seyed Kazem; Nojomi, Marzieh; Leo, Diego De; Saeed, Khalid

2016-01-01

Alcohol use and its disorders are associated with increased risk of suicidal behaviors Research has shown that 6-8% of those who use alcohol have a history of suicide attempt. Given the prohibition of alcohol use legally, the increased alcohol consumption, and the lack of strong evidence in favor of its use associated with suicide in Iran, this study was conducted to determine the link between suicide attempt and alcohol abuse. The case-crossover method was used in this research. Out of 305 referrals to the emergency room due to a suicide attempt, 100 reported drinking alcohol up to six hours before their attempt. Paired Matching and Usual Frequency were employed to analyze the data with STATA 12.0. The probability of attempting suicide up to six hours after drinking alcohol appeared increased by 27 times (95% CI: 8.1-60.4). Separate analysis for each of these hours from the first to the sixth hour after alcohol use was also performed. Fifty percent of attempted suicides happened one hour after alcohol use. Relative risk for the first and second hour was 10% and 5% respectively. Alcohol use is a strong proximal risk factor for attempted suicide among Iranian subjects. Prevention of alcohol use should be considered in setting up of the national Suicide attempt prevention program. PMID:26925903

Synchronized shocks in an inhomogeneous exclusion process

NASA Astrophysics Data System (ADS)

Arita, Chikashi

2015-11-01

We study an exclusion process with 4 segments, which was recently introduced by T. Banerjee, N. Sarkar and A. Basu (J. Stat. Mech. (2015) P01024). The segments have hopping rates 1, r(<1) , 1 and r, respectively. In a certain parameter region, two shocks appear, which are not static but synchronized. We explore dynamical properties of each shock and correlation of shocks, by means of the so-called second-class particle. The mean-squared displacement of shocks has three diffusive regimes, and the asymptotic diffusion coefficient is different from the known formula. In some time interval, it also exhibits sub-diffusion, being proportional to t1/2 . Furthermore we introduce a correlation function and a crossover time, in order to quantitatively characterize the synchronization. We numerically estimate the dynamical exponent for the crossover time. We also revisit the 2-segment case and the open boundary condition for comparison.

Graded exposure in vivo in the treatment of pain-related fear: a replicated single-case experimental design in four patients with chronic low back pain.

PubMed

Vlaeyen, J W; de Jong, J; Geilen, M; Heuts, P H; van Breukelen, G

2001-02-01

The aim of this investigation was to examine the effectiveness of a graded exposure in vivo treatment with behavioural experiments as compared to usual graded activity in reducing pain-related fears, catastrophising and pain disability in chronic low back pain patients reporting substantial fear of movement/(re)injury. Included in the study were four consecutive CLBP patients who were referred for outpatient behavioural rehabilitation, and who reported substantial fear of movement/(re)injury (Tampa Scale for Kinesiophobia score>40). A replicated single-case cross-over design was used. After a no-treatment baseline measurement period, the patients were randomly assigned to one of two interventions. In intervention A, patients received the exposure first, followed by graded activity. In intervention B, the sequence of treatment modules was reversed. Sixty-three daily measures of pain-related cognitions and fears were recorded with visual analogue scales. Before and after the treatment, the following measures were taken: pain-related fear, pain catastrophising, pain control and pain disability. Using time series analysis on the daily measures of pain-related cognitions and fears, we found that improvements only occurred during the graded exposure in vivo, and not during the graded activity, irrespective of the treatment order. Analysis of the pre-post treatment differences also revealed that decreases in pain-related fear concurred with decreases in pain catastrophising and pain disability, and in half of the cases an increase in pain control. This study shows that the external validity of exposure in vivo also extends to the subgroup of chronic low back pain patients who report substantial fear of movement/(re)injury.

Transient risk factors for acute traumatic hand injuries: a case‐crossover study in Hong Kong

PubMed Central

Chow, C Y; Lee, H; Lau, J; Yu, I T S

2007-01-01

Objectives To identify the remediable transient risk factors of occupational hand injuries in Hong Kong in order to guide the development of prevention strategies. Methods The case‐crossover study design was adopted. Study subjects were workers with acute hand injuries presenting to the government Occupational Medicine Unit for compensation claims within 90 days from the date of injury. Detailed information on exposures to specific transient factors during the 60 minutes prior to the occurrence of the injury, during the same time interval on the day prior to the injury, as well as the usual exposure during the past work‐month was obtained through telephone interviews. Both matched‐pair interval approach and usual frequency approach were adopted to assess the associations between transient exposures in the workplace and the short‐term risk of sustaining a hand injury. Results A total of 196 injured workers were interviewed. The results of the matched‐pair interval analysis matched well with the results obtained using the usual frequency analysis. Seven significant transient risk factors were identified: using malfunctioning equipment/materials, using a different work method, performing an unusual work task, working overtime, feeling ill, being distracted and rushing, with odds ratios ranging from 10.5 to 26.0 in the matched‐pair interval analysis and relative risks ranging between 8.0 and 28.3 with the usual frequency analysis. Wearing gloves was found to have an insignificant protective effect on the occurrence of hand injury in both analyses. Conclusions Using the case‐crossover study design for acute occupational hand injuries, seven transient risk factors that were mostly modifiable were identified. It is suggested that workers and their employers should increase their awareness of these risk factors, and efforts should be made to avoid exposures to these factors by means of engineering and administrative controls supplemented by safety education and training. PMID:16973734

Audiovisual distraction for pain relief in paediatric inpatients: A crossover study.

PubMed

Oliveira, N C A C; Santos, J L F; Linhares, M B M

2017-01-01

Pain is a stressful experience that can have a negative impact on child development. The aim of this crossover study was to examine the efficacy of audiovisual distraction for acute pain relief in paediatric inpatients. The sample comprised 40 inpatients (6-11 years) who underwent painful puncture procedures. The participants were randomized into two groups, and all children received the intervention and served as their own controls. Stress and pain-catastrophizing assessments were initially performed using the Child Stress Scale and Pain Catastrophizing Scale for Children, with the aim of controlling these variables. The pain assessment was performed using a Visual Analog Scale and the Faces Pain Scale-Revised after the painful procedures. Group 1 received audiovisual distraction before and during the puncture procedure, which was performed again without intervention on another day. The procedure was reversed in Group 2. Audiovisual distraction used animated short films. A 2 × 2 × 2 analysis of variance for 2 × 2 crossover study was performed, with a 5% level of statistical significance. The two groups had similar baseline measures of stress and pain catastrophizing. A significant difference was found between periods with and without distraction in both groups, in which scores on both pain scales were lower during distraction compared with no intervention. The sequence of exposure to the distraction intervention in both groups and first versus second painful procedure during which the distraction was performed also significantly influenced the efficacy of the distraction intervention. Audiovisual distraction effectively reduced the intensity of pain perception in paediatric inpatients. The crossover study design provides a better understanding of the power effects of distraction for acute pain management. Audiovisual distraction was a powerful and effective non-pharmacological intervention for pain relief in paediatric inpatients. The effects were detected in subsequent acute painful procedures. © 2016 European Pain Federation - EFIC®.

Comparative Performance in Single-Port Versus Multiport Minimally Invasive Surgery, and Small Versus Large Operative Working Spaces: A Preclinical Randomized Crossover Trial.

PubMed

Marcus, Hani J; Seneci, Carlo A; Hughes-Hallett, Archie; Cundy, Thomas P; Nandi, Dipankar; Yang, Guang-Zhong; Darzi, Ara

2016-04-01

Surgical approaches such as transanal endoscopic microsurgery, which utilize small operative working spaces, and are necessarily single-port, are particularly demanding with standard instruments and have not been widely adopted. The aim of this study was to compare simultaneously surgical performance in single-port versus multiport approaches, and small versus large working spaces. Ten novice, 4 intermediate, and 1 expert surgeons were recruited from a university hospital. A preclinical randomized crossover study design was implemented, comparing performance under the following conditions: (1) multiport approach and large working space, (2) multiport approach and intermediate working space, (3) single-port approach and large working space, (4) single-port approach and intermediate working space, and (5) single-port approach and small working space. In each case, participants performed a peg transfer and pattern cutting tasks, and each task repetition was scored. Intermediate and expert surgeons performed significantly better than novices in all conditions (P < .05). Performance in single-port surgery was significantly worse than multiport surgery (P < .01). In multiport surgery, there was a nonsignificant trend toward worsened performance in the intermediate versus large working space. In single-port surgery, there was a converse trend; performances in the intermediate and small working spaces were significantly better than in the large working space. Single-port approaches were significantly more technically challenging than multiport approaches, possibly reflecting loss of instrument triangulation. Surprisingly, in single-port approaches, in which triangulation was no longer a factor, performance in large working spaces was worse than in intermediate and small working spaces. © The Author(s) 2015.

Air pollution and ED visits for asthma in Australian children: a case-crossover analysis.

PubMed

Jalaludin, Bin; Khalaj, Behnoosh; Sheppeard, Vicky; Morgan, Geoff

2008-08-01

We aimed to determine the effects of ambient air pollutants on emergency department (ED) visits for asthma in children. We obtained routinely collected ED visit data for asthma (ICD9 493) and air pollution (PM(10), PM(2.5), O(3), NO(2), CO and SO(2)) and meteorological data for metropolitan Sydney for 1997-2001. We used the time stratified case-crossover design and conditional logistic regression to model the association between air pollutants and ED visits for four age-groups (1-4, 5-9, 10-14 and 1-14 years). Estimated relative risks for asthma ED visits were calculated for an exposure corresponding to the inter-quartile range in pollutant level. We included same day average temperature, same day relative humidity, daily temperature range, school holidays and public holidays in all models. Associations between ambient air pollutants and ED visits for asthma in children were most consistent for all six air pollutants in the 1-4 years age-group, for particulates and CO in the 5-9 years age-group and for CO in the 10-14 years age-group. The greatest effects were most consistently observed for lag 0 and effects were greater in the warm months for particulates, O(3) and NO(2). In two pollutant models, effect sizes were generally smaller compared to those derived from single pollutant models. We observed the effects of ambient air pollutants on ED attendances for asthma in a city where the ambient concentrations of air pollutants are relatively low.

Between-Batch Pharmacokinetic Variability Inflates Type I Error Rate in Conventional Bioequivalence Trials: A Randomized Advair Diskus Clinical Trial.

PubMed

Burmeister Getz, E; Carroll, K J; Mielke, J; Benet, L Z; Jones, B

2017-03-01

We previously demonstrated pharmacokinetic differences among manufacturing batches of a US Food and Drug Administration (FDA)-approved dry powder inhalation product (Advair Diskus 100/50) large enough to establish between-batch bio-inequivalence. Here, we provide independent confirmation of pharmacokinetic bio-inequivalence among Advair Diskus 100/50 batches, and quantify residual and between-batch variance component magnitudes. These variance estimates are used to consider the type I error rate of the FDA's current two-way crossover design recommendation. When between-batch pharmacokinetic variability is substantial, the conventional two-way crossover design cannot accomplish the objectives of FDA's statistical bioequivalence test (i.e., cannot accurately estimate the test/reference ratio and associated confidence interval). The two-way crossover, which ignores between-batch pharmacokinetic variability, yields an artificially narrow confidence interval on the product comparison. The unavoidable consequence is type I error rate inflation, to ∼25%, when between-batch pharmacokinetic variability is nonzero. This risk of a false bioequivalence conclusion is substantially higher than asserted by regulators as acceptable consumer risk (5%). © 2016 The Authors Clinical Pharmacology & Therapeutics published by Wiley Periodicals, Inc. on behalf of The American Society for Clinical Pharmacology and Therapeutics.

Impact of urban atmospheric pollution on coronary disease.

PubMed

Maitre, Anne; Bonneterre, Vincent; Huillard, Laurent; Sabatier, Philippe; de Gaudemaris, Régis

2006-10-01

Recent epidemiological findings have suggested that urban atmospheric pollution may have adverse effects on the cardiovascular system as well as on the respiratory system. We carried out an exhaustive search of published studies investigating links between coronary heart disease and urban atmospheric pollution. The review was conducted on cited articles published between 1994 and 2005 and whose main objective was to measure the risk of ischaemic heart diseases related to urban pollution. Of the 236 references identified, 46 epidemiological studies were selected for analysis on the basis of pre-defined criteria. The studies were analysed according to short-term effects (time series and case-crossover designs) and long-term effects (case-control and cohort studies). A link between coronary heart disease and at least one of the pollutants studied (PM10, O3, NOx, CO, SO2) emerged in 40 publications. Particulate matter, nitrogen oxides, and carbon monoxide were the pollutants most often linked with coronary heart disease. The association was inconstant for O3. Although the mean mortality or morbidity risk related to urban atmospheric pollution is low compared with that associated with other better-known risk factors, its impact on health is nevertheless major because of the large number of people who are exposed. This exhaustive review supports the possibility that urban pollution is indeed an environmental cardiovascular risk factor and should be considered as such by the cardiologists.

Blood volume-monitored regulation of ultrafiltration in fluid-overloaded hemodialysis patients: study protocol for a randomized controlled trial

PubMed Central

2012-01-01

Background Data generated with the body composition monitor (BCM, Fresenius) show, based on bioimpedance technology, that chronic fluid overload in hemodialysis patients is associated with poor survival. However, removing excess fluid by lowering dry weight can be accompanied by intradialytic and postdialytic complications. Here, we aim at testing the hypothesis that, in comparison to conventional hemodialysis, blood volume-monitored regulation of ultrafiltration and dialysate conductivity (UCR) and/or regulation of ultrafiltration and temperature (UTR) will decrease complications when ultrafiltration volumes are systematically increased in fluid-overloaded hemodialysis patients. Methods/design BCM measurements yield results on fluid overload (in liters), relative to extracellular water (ECW). In this prospective, multicenter, triple-arm, parallel-group, crossover, randomized, controlled clinical trial, we use BCM measurements, routinely introduced in our three maintenance hemodialysis centers shortly prior to the start of the study, to recruit sixty hemodialysis patients with fluid overload (defined as ≥15% ECW). Patients are randomized 1:1:1 into UCR, UTR and conventional hemodialysis groups. BCM-determined, ‘final’ dry weight is set to normohydration weight −7% of ECW postdialysis, and reached by reducing the previous dry weight, in steps of 0.1 kg per 10 kg body weight, during 12 hemodialysis sessions (one study phase). In case of intradialytic complications, dry weight reduction is decreased, according to a prespecified algorithm. A comparison of intra- and post-dialytic complications among study groups constitutes the primary endpoint. In addition, we will assess relative weight reduction, changes in residual renal function, quality of life measures, and predialysis levels of various laboratory parameters including C-reactive protein, troponin T, and N-terminal pro-B-type natriuretic peptide, before and after the first study phase (secondary outcome parameters). Discussion Patients are not requested to revert to their initial degree of fluid overload after each study phase. Therefore, the crossover design of the present study merely serves the purpose of secondary endpoint evaluation, for example to determine patient choice of treatment modality. Previous studies on blood volume monitoring have yielded inconsistent results. Since we include only patients with BCM-determined fluid overload, we expect a benefit for all study participants, due to strict fluid management, which decreases the mortality risk of hemodialysis patients. Trial registration ClinicalTrials.gov, NCT01416753 PMID:22682149

Automated global structure extraction for effective local building block processing in XCS.

PubMed

Butz, Martin V; Pelikan, Martin; Llorà, Xavier; Goldberg, David E

2006-01-01

Learning Classifier Systems (LCSs), such as the accuracy-based XCS, evolve distributed problem solutions represented by a population of rules. During evolution, features are specialized, propagated, and recombined to provide increasingly accurate subsolutions. Recently, it was shown that, as in conventional genetic algorithms (GAs), some problems require efficient processing of subsets of features to find problem solutions efficiently. In such problems, standard variation operators of genetic and evolutionary algorithms used in LCSs suffer from potential disruption of groups of interacting features, resulting in poor performance. This paper introduces efficient crossover operators to XCS by incorporating techniques derived from competent GAs: the extended compact GA (ECGA) and the Bayesian optimization algorithm (BOA). Instead of simple crossover operators such as uniform crossover or one-point crossover, ECGA or BOA-derived mechanisms are used to build a probabilistic model of the global population and to generate offspring classifiers locally using the model. Several offspring generation variations are introduced and evaluated. The results show that it is possible to achieve performance similar to runs with an informed crossover operator that is specifically designed to yield ideal problem-dependent exploration, exploiting provided problem structure information. Thus, we create the first competent LCSs, XCS/ECGA and XCS/BOA, that detect dependency structures online and propagate corresponding lower-level dependency structures effectively without any information about these structures given in advance.

Potentially disruptive life events: what are the immediate impacts on chronic disease management? A case-crossover analysis.

PubMed

Lauffenburger, Julie C; Gagne, Joshua J; Song, Zirui; Brill, Gregory; Choudhry, Niteesh K

2016-08-04

To explore the association between unexpected potentially disruptive life events in a patient or family member that may challenge an individual's ability to take medications as prescribed and the discontinuation of evidence-based medications for common, chronic conditions. Understanding the relationship between medication adherence and life stressors, especially those that can be identified using administrative data, may help identify patients at risk of non-adherence. Observational self-controlled case-crossover design. Individuals in a nationally representative US commercial health insurance database. Adult individuals who initiated an oral hypoglycaemic, antihypertensive and/or statin and subsequently stopped the medication for ≥90 days. Potentially disruptive life events among patients and their family members measured in the 30 days just before the medication was discontinued ('hazard period') compared with the 30 days before this period ('control period'). These events included personal injury, hospitalisation, emergency room visits, changes in insurance coverage, acute stress or acute anxiety. Among the 326 519 patients meeting study criteria who discontinued their chronic disease medications, 88 896 (27.2%) experienced at least one potentially disruptive life event. Newly experiencing an injury (OR: 1.26, 95% CI 1.12 to 1.42), an emergency room visit (OR: 1.19, 95% CI 1.13 to 1.26) and acute stress (OR: 1.19, 95% CI 1.08 to 1.31) were associated with discontinuation. Life events among patients' family members did not appear to be associated with medication discontinuation or occurred less frequently just prior to discontinuation. Potentially disruptive life events among individuals identified using routinely collected claims data are associated with discontinuation of chronic disease medications. Awareness of these events may help providers or payers identify patients at risk of non-adherence to maximise patient outcomes. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Does air pollution trigger suicide? A case-crossover analysis of suicide deaths over the life span.

PubMed

Casas, Lidia; Cox, Bianca; Bauwelinck, Mariska; Nemery, Benoit; Deboosere, Patrick; Nawrot, Tim Steve

2017-11-01

In addition to underlying health disorders and socio-economic or community factors, air pollution may trigger suicide mortality. This study evaluates the association between short-term variation in air pollution and 10 years of suicide mortality in Belgium. In a bidirectional time-stratified case-crossover design, 20,533 suicide deaths registered between January 1st 2002 and December 31st 2011 were matched by temperature with control days from the same month and year. We used municipality-level air pollution [particulate matter (PM 10 ) and O 3 concentrations] data and meteorology data. We applied conditional logistic regression models adjusted for duration of sunshine and day of the week to obtain odds ratios (OR) and their 95% CI for an increase of 10 µg/m 3 in pollutant concentrations over different lag periods (lag 0, 0-1, 0-2, 0-3, 0-4, 0-5, and 0-6 days). Effect modification by season and age was investigated by including interaction terms. We observed significant associations of PM 10 and O 3 with suicide during summer (OR ranging from 1.02 to 1.07, p-values <0.05). For O 3 , significant associations were also observed during spring and autumn. Age significantly modified the associations with PM 10 , with statistically significant associations observed only among 5-14 year old children (lag 0-6: OR = 1.45; 95% CI: 1.03-2.04) and ≥85 years old (e.g. lag 0-4: OR = 1.17; 95% CI: 1.06-1.29). Recent increases in outdoor air pollutants such as PM 10 or O 3 can trigger suicide, particularly during warm periods, even at concentrations below the European thresholds. Furthermore, PM 10 may have strong trigger effects among children and elderly population.

The impact of ambient air pollution on suicide mortality: a case-crossover study in Guangzhou, China.

PubMed

Lin, Guo-Zhen; Li, Li; Song, Yun-Feng; Zhou, Ying-Xue; Shen, Shuang-Quan; Ou, Chun-Quan

2016-08-30

Preventing suicide is a global imperative. Although the effects of social and individual risk factors of suicide have been widely investigated, evidence of environmental effects of exposure to air pollution is scarce. We investigated the effects of ambient air pollution on suicide mortality in Guangzhou, China during 2003-2012. A conditional logistic regression analysis with a time-stratified case-crossover design was performed to assess the effects of daily exposure to three standard air pollutants, including particulate matter less than 10 μm in aerodynamic diameter (PM10), sulphur dioxide (SO2) and nitrogen dioxide (NO2), on suicide mortality, after adjusting for the confounding effects of daily mean temperature, relative humidity, atmospheric pressure and sunshine duration. Further analyses were stratified by season, gender, age group, educational attainment and suicide type. Between 2003 and 2012, there were a total of 1 550 registered suicide deaths in Guangzhou. A significant increase in suicide risk were associated with interquartile-range increases in the concentration of air pollutant, with an odds ratio of 1.13 (95 % confidence interval (CI): 1.01, 1.27) and 1.15 (95 % CI: 1.03, 1.28) for PM10 and NO2 at lag 02, and 1.12 (95 % CI: 1.02, 1.23) for SO2 at lag 01, respectively. The suicide risks related to air pollution for males and people with high education level were higher than for females and those with low education level, respectively. Significant air pollution effects were found on violent suicide mortality and in cool season but not on non-violent suicide mortality or in warm season. Suicide risk was positively associated with ambient air pollution levels. This finding would provide important information for the health impact assessment of air pollution and for the development of effective strategies and interventions for the prevention of suicide.

Short-term risk of hospitalization for asthma or bronchiolitis in children living near an aluminum smelter.

PubMed

Lewin, Antoine; Buteau, Stéphane; Brand, Allan; Kosatsky, Tom; Smargiassi, Audrey

2013-01-01

Few studies have measured the effect of short-term exposure to industrial emissions on the respiratory health of children. Here we estimate the risk of hospitalization for asthma and bronchiolitis in young children associated with their recent exposure to emissions from an aluminum smelter. We used a case-crossover design to assess the risk of hospitalization, February 1999-December 2008, in relation to short-term variation in levels of exposure among children 0-4 years old living less than 7.5 km from the smelter. The percentage of hours per day that the residence of a hospitalized child was in the shadow of winds crossing the smelter was used to estimate the effect of wind-borne emissions on case and crossover days. Community-wide pollutant exposure was estimated through daily mean and daily maximum SO2 and PM2.5 concentrations measured at a fixed monitoring site near the smelter. Odds ratios (OR) were estimated using conditional logistic regressions. The risk of same-day hospitalization for asthma or bronchiolitis increased with the percentage of hours in a day that a child's residence was downwind of the smelter. For children aged 2-4 years, the OR was 1.27 (95% CI=1.03-1.56; n=103 hospitalizations), for an interquartile range (IQR) of 21% of hours being downwind. In this age group, the OR with PM2.5 daily mean levels was slightly smaller than with the hours downwind (OR: 1.22 for an IQR of 15.7 μg/m(3), 95% CI=1.03-1.44; n=94 hospitalizations). Trends were observed between hospitalizations and levels of SO2 for children 2-4 years old. Increasing short-term exposure to emissions from a Quebec aluminum smelter was associated with an increased risk of hospitalization for asthma and bronchiolitis in young children who live nearby. Estimating exposure through records of wind direction allows for the integration of exposure to all pollutants carried from the smelter stack.

The Gluten-Free, Casein-Free Diet in Autism: Results of a Preliminary Double Blind Clinical Trial

ERIC Educational Resources Information Center

Elder, Jennifer Harrison; Shankar, Meena; Shuster, Jonathan; Theriaque, Douglas; Burns, Sylvia; Sherrill, Lindsay

2006-01-01

This study tested the efficacy of a gluten-free and casein-free (GFCF) diet in treating autism using a randomized, double blind repeated measures crossover design. The sample included 15 children aged 2-16 years with autism spectrum disorder. Data on autistic symptoms and urinary peptide levels were collected in the subjects' homes over the 12…

Pharmacokinetic comparison of a fixed-dose combination versus concomitant administration of fimasartan, amlodipine, and rosuvastatin using partial replicated design in healthy adult subjects.

PubMed

Oh, Minkyung; Ghim, Jong-Lyul; Park, Sung-Eun; Kim, Eun-Young; Shin, Jae-Gook

2018-01-01

The aim of this study was to compare the pharmacokinetics (PK) and safety profiles of a fixed-dose combination (FDC) formulation of fimasartan, amlodipine, and rosuvastatin with the co-administration of the two products by using a replicated crossover study design in healthy male subjects. This was an open-label, randomized, three-sequence, three-period replicated crossover study in healthy male subjects. The replicated crossover design was done because of high coefficient of variation of PK parameter for fimasartan, that is, >30%. With a 14 days washout period, an FDC tablet containing 60 mg fimasartan, 10 mg amlodipine, and 20 mg rosuvastatin was administered only once, and separate formulations of fimasartan/amlodipine 60 mg/10 mg FDC tablet and 20 mg rosuvastatin tablet administered twice. Blood samples were collected up to 72 hours following drug administration. The plasma concentrations of fimasartan, amlodipine, and rosuvastatin were measured by liquid chromatography tandem mass spectrometry. Safety was assessed by evaluating vital signs, clinical laboratory parameters, physical examinations, and medical interviews. The geometric mean ratios and 90% confidence intervals (CIs) for the maximum plasma concentration (C max ) and area under the curve from time zero to the last measurable sampling time (AUC t ) were 1.0776 (0.9201-1.2622) and 0.9978 (0.9538-1.0439) for fimasartan, 1.0038 (0.9782-1.0301) and 1.0055 (0.9828-1.0288) for amlodipine, and 1.0006 (0.9290-1.0776) and 0.9986 (0.9532-1.0461) for rosuvastatin, respectively. A total of 22 adverse events (AEs) were reported by 60 subjects; there were no significant differences in the incidence of AEs between the two groups. The 90% CI of the C max of fimasartan was within the widened acceptance limit, ln(0.6984)-ln(1.4319). The 90% CIs of the other PK parameters for drugs were between ln(0.8) and ln(1.25). These results suggest that the FDC formulation is pharmacokinetically bioequivalent and has a similar safety profile, to the co-administration of its three constituent drugs.

Effect of skipping breakfast on subsequent energy intake.

PubMed

Levitsky, David A; Pacanowski, Carly R

2013-07-02

The objective was to examine the effect of consuming breakfast on subsequent energy intake. Participants who habitually ate breakfast and those who skipped breakfast were recruited for two studies. Using a randomized crossover design, the first study examined the effect of having participants consume either (a) no breakfast, (b) a high carbohydrate breakfast (335 kcals), or (c) a high fiber breakfast (360 kcals) on three occasions and measured ad libitum intake at lunch. The second study again used a randomized crossover design but with a larger, normal carbohydrate breakfast consumed ad libtum. Intake averaged 624 kcals and subsequent food intake was measured throughout the day. Participants ate only foods served from the Cornell Human Metabolic Research Unit where all foods were weighed before and after consumption. In the first study, neither eating breakfast nor the kind of breakfast consumed had an effect on the amount consumed at lunch despite a reduction in hunger ratings. In the second study, intake at lunch as well as hunger ratings were significantly increased after skipping breakfast (by 144 kcal), leaving a net caloric deficit of 408 kcal by the end of the day. These data are consistent with published literature demonstrating that skipping a meal does not result in accurate energy compensation at subsequent meals and suggests that skipping breakfast may be an effective means to reduce daily energy intake in some adults. Copyright © 2013 Elsevier Inc. All rights reserved.

Effects of Subsensory Noise and Fatigue on Knee Landing and Cross-over Cutting Biomechanics in Male Athletes.

PubMed

Qu, Xingda; Jiang, Jianxin; Hu, Xinyao

2018-06-01

The objective of this study was to examine the effects of subsensory noise and fatigue on knee biomechanics during the athletic task of landing followed by cross-over cutting. A total of 32 healthy male athletes participated in the study. They were evenly divided into 2 groups: no fatigue group and fatigue group. Fatigue was induced to the lower extremity by a repetitive squatting exercise in the fatigue group. Subsensory noise was generated by linear miniature vibrators bilaterally placed around the knee joints. During data collection, the participants were instructed to perform landing followed by cross-over cutting in both the subsensory on and off conditions. Dependent variables were selected to assess knee biomechanics in the phases of landing and cross-over cutting, separately. Results showed that fatigue resulted in larger knee flexion during landing and larger knee internal rotation during cross-over cutting. Subsensory noise was found to reduce knee rotation impulse during cross-over cutting. These findings suggest that cross-over cutting is more dangerous than landing in the fatigue condition, and subsensory noise may lead to changes in knee biomechanics consistent with reduced risk of anterior cruciate ligament injuries, but the changes may be task-specific.

Impact of membrane characteristics on the performance and cycling of the Br₂–H₂ redox flow cell

DOE PAGES

Tucker, Michael C.; Cho, Kyu Taek; Spingler, Franz B.; ...

2015-03-04

The Br₂/H₂ redox flow cell shows promise as a high-power, low-cost energy storage device. In this paper, the effect of various aspects of material selection and processing of proton exchange membranes on the operation of the Br₂/H₂ redox flow cell is determined. Membrane properties have a significant impact on the performance and efficiency of the system. In particular, there is a tradeoff between conductivity and crossover, where conductivity limits system efficiency at high current density and crossover limits efficiency at low current density. The impact of thickness, pretreatment procedure, swelling state during cell assembly, equivalent weight, membrane reinforcement, and additionmore » of a microporous separator layer on this tradeoff is assessed. NR212 (50 μm) pretreated by soaking in 70 °C water is found to be optimal for the studied operating conditions. For this case, an energy efficiency of greater than 75% is achieved for current density up to 400 mA cm⁻², with a maximum obtainable energy efficiency of 88%. A cell with this membrane was cycled continuously for 3164 h. Membrane transport properties, including conductivity and bromine and water crossover, were found to decrease moderately upon cycling but remained higher than those for the as-received membrane.« less

Investigations of botanicals on food intake, satiety, weight loss and oxidative stress: study protocol of a double-blind, placebo-controlled, crossover study.

PubMed

Anton, Stephen D; Shuster, Jonathan; Leeuwenburgh, Christiaan

2011-11-01

Botanicals represent an important and underexplored source of potential new therapies that may facilitate caloric restriction and thereby may produce long-term weight loss. In particular, one promising botanical that may reduce food intake and body weight by affecting neuroendocrine pathways related to satiety is hydroxycitric acid (HCA) derived from Garcinia cambogia Desr. The objective of this article is to describe the protocol of a clinical trial designed to directly test the effects of Garcinia cambogia-derived HCA on food intake, satiety, weight loss and oxidative stress levels, and to serve as a model for similar trials. A total of 48 healthy, overweight or obese individuals (with a body mass index range of 25.0 to 39.9 kg/m(2)) between the ages of 50 to 70 will participate in this double-blind, placebo-controlled, crossover study designed to examine the effects of two doses of Garcinia cambogia-derived HCA on food intake, satiety, weight loss, and oxidative stress levels. Food intake represents the primary outcome measure and is calculated based on the total calories consumed at breakfast, lunch, and dinner meals during each test meal day. This study can be completed with far fewer subjects than a parallel design. Of the numerous botanical compounds, the compound Garcinia cambogia-derived HCA is selected for testing in the present study because of its potential to safely reduce food intake, body weight, and oxidative stress levels. We will review potential mechanisms of action and safety parameters throughout this clinical trial. ClinicalTrials.gov (Identifier: NCT01238887).

Threshold Levels of Infant and Under-Five Mortality for Crossover between Life Expectancies at Ages Zero, One and Five in India: A Decomposition Analysis

PubMed Central

Dubey, Manisha

2015-01-01

Objectives Under the prevailing conditions of imbalanced life table and historic gender discrimination in India, our study examines crossover between life expectancies at ages zero, one and five years for India and quantifies the relative share of infant and under-five mortality towards this crossover. Methods We estimate threshold levels of infant and under-five mortality required for crossover using age specific death rates during 1981–2009 for 16 Indian states by sex (comprising of India’s 90% population in 2011). Kitagawa decomposition equations were used to analyse relative share of infant and under-five mortality towards crossover. Findings India experienced crossover between life expectancies at ages zero and five in 2004 for menand in 2009 for women; eleven and nine Indian states have experienced this crossover for men and women, respectively. Men usually experienced crossover four years earlier than the women. Improvements in mortality below ages five have mostly contributed towards this crossover. Life expectancy at age one exceeds that at age zero for both men and women in India except for Kerala (the only state to experience this crossover in 2000 for men and 1999 for women). Conclusions For India, using life expectancy at age zero and under-five mortality rate together may be more meaningful to measure overall health of its people until the crossover. Delayed crossover for women, despite higher life expectancy at birth than for men reiterates that Indian women are still disadvantaged and hence use of life expectancies at ages zero, one and five become important for India. Greater programmatic efforts to control leading causes of death during the first month and 1–59 months in high child mortality areas can help India to attain this crossover early. PMID:26683617

Suicide and Ambient Temperature in East Asian Countries: A Time-Stratified Case-Crossover Analysis

PubMed Central

Kim, Yoonhee; Honda, Yasushi; Guo, Yue Leon; Chen, Bing-Yu; Woo, Jong-Min; Ebi, Kristie L.

2015-01-01

Background A limited number of studies suggest that ambient temperature contributes to suicide; these studies typically focus on a single nation and use temporally and spatially aggregated data. Objective We evaluated the association between ambient temperature and suicide in multiple cities in three East Asian countries. Methods A time-stratified case-crossover method was used to explore the relationship between temperature and suicide, adjusting for potential time-varying confounders and time-invariant individual characteristics. Sex- and age-specific associations of temperature with suicide were estimated, as were interactions between temperature and these variables. A random-effects meta-analysis was used to estimate country-specific pooled associations of temperature with suicide. Results An increase in temperature corresponding to half of the city-specific standard deviation was positively associated with suicide in most cities, although average suicide rates varied substantially. Pooled country-level effect estimates were 7.8% (95% CI: 5.0, 10.8%) for a 2.3°C increase in ambient temperature in Taiwan, 6.8% (95% CI: 5.4, 8.2%) for a 4.7°C increase in Korea, and 4.5% (95% CI: 3.3, 5.7%) for a 4.2°C increase in Japan. The association between temperature and suicide was significant even after adjusting for sunshine duration; the association between sunshine and suicide was not significant. The associations were greater among men than women in 12 of the 15 cities although not significantly so. There was little evidence of a consistent pattern of associations with age. In general, associations were strongest with temperature on the same day or the previous day, with little evidence of associations with temperature over longer lags (up to 5 days). Conclusions We estimated consistent positive associations between suicide and elevated ambient temperature in three East Asian countries, regardless of country, sex, and age. Citation Kim Y, Kim H, Honda Y, Guo YL, Chen BY, Woo JM, Ebi KL. 2016. Suicide and ambient temperature in East Asian countries: a time-stratified case-crossover analysis. Environ Health Perspect 124:75–80; http://dx.doi.org/10.1289/ehp.1409392 PMID:26069051

A case-crossover study of sleep, fatigue, and other transient exposures at workplace and the risk of non-fatal occupational injuries among the employees of an Italian academic hospital.

PubMed

Valent, Francesca; Mariuz, Marika; Liva, Giulia; Bellomo, Fabrizio; De Corti, Daniela; Degan, Stefania; Ferrazzano, Alberto; Brusaferro, Silvio

2016-11-18

Transient exposure with acute effect has been shown to affect the risk of occupational injuries in various industrial settings and at the healthcare workplace. The objective of this study has been to identify transient exposures related to occupational injury risk in an Italian teaching hospital. A case-crossover study was conducted among the employees of the University Hospital of Udine who reported an occupational injury, commuting accident, or incident involving biological risk in a 15-month period in the years 2013 and 2014. The matched-pair interval approach was used to assess the role of acute sleep deprivation whereas the usual frequency approach was used for other 13 transient exposures. Sleep hours were not associated with the risk of injuries whereas a significant risk increase was associated with fatigue, rush, distraction, emergency situations, teaching to or being taught by someone, non-compliant patients, bloody operative/work field, excess noise, complex procedures, and anger. We identified transient exposures that increased the risk of occupational injuries in an Italian teaching hospital, providing indications for interventions to increase workers' safety at the healthcare workplace. Int J Occup Med Environ Health 2016;29(6):1001-1009. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

Switching to a 10-day Mediterranean-style diet improves mood and cardiovascular function in a controlled crossover study.

PubMed

Lee, Jaime; Pase, Matthew; Pipingas, Andrew; Raubenheimer, Jessica; Thurgood, Madeline; Villalon, Lorena; Macpherson, Helen; Gibbs, Amy; Scholey, Andrew

2015-05-01

Even short-term adherence to a Mediterranean-style diet may benefit aspects of psychological functioning. The aim of the present study was to assess the effects of switching to a 10-d Mediterranean-style diet on mood, cognition, and cardiovascular measures. Using a crossover design, 24 women were randomly assigned to either the diet change (where they switched to a Mediterranean-style diet) or no diet change (normal diet) condition for 10 days before switching to the other condition for the same duration. Mood, cognition, and cardiovascular measures of blood pressure, blood flow velocity, and arterial stiffness were assessed at baseline and at the completion of the two diets (days 11 and 22). Independent of whether the Mediterranean-style diet was undertaken before or after the crossover, it was associated with significantly elevated contentment and alertness, and significantly reduced confusion. Additionally, aspects of cognition, such as memory recall, improved significantly as a result of switching to the Mediterranean-style diet. Regarding cardiovascular measures, there was a significant reduction in augmentation pressure associated with the Mediterranean-style diet intervention, but blood flow velocity through the common carotid artery did not change. This Mediterranean-style diet has the potential to enhance aspects of mood, cognition, and cardiovascular function in a young, healthy adult sample. Copyright © 2015 Elsevier Inc. All rights reserved.

A Time-Stratified Case-Crossover Study of Ambient Ozone Exposure and Emergency Department Visits for Specific Respiratory Diagnoses in California (2005–2008)

PubMed Central

Malig, Brian J.; Pearson, Dharshani L.; Chang, Yun Brenda; Broadwin, Rachel; Basu, Rupa; Green, Rochelle S.; Ostro, Bart

2015-01-01

Background: Studies have explored ozone’s connection to asthma and total respiratory emergency department visits (EDVs) but have neglected other specific respiratory diagnoses despite hypotheses relating ozone to respiratory infections and allergic responses. Objective: We examined relationships between ozone and EDVs for respiratory visits, including specifically acute respiratory infections (ARI), asthma, pneumonia, chronic obstructive pulmonary disease (COPD), and upper respiratory tract inflammation (URTI). Methods: We conducted a multi-site time-stratified case-crossover study of ozone exposures for approximately 3.7 million respiratory EDVs from 2005 through 2008 among California residents living within 20 km of an ozone monitor. Conditional logistic regression was used to estimate associations by climate zone. Random effects meta-analysis was then applied to estimate pooled excess risks (ER). Effect modification by season, distance from the monitor and individual demographic characteristics (i.e., age, race/ethnicity, sex, and payment method), and confounding by other gaseous air pollutants were also investigated. Meta-regression was utilized to explore how climate zone–level meteorological, demographic, and regional differences influenced estimates. Results: We observed ozone-associated increases in all respiratory, asthma, and ARI visits, which were slightly larger in the warm season [asthma ER per 10-ppb increase in mean of same and previous 3 days ozone exposure (lag03) = 2.7%, 95% CI: 1.5, 3.9; ARI ERlag03 = 1.4%, 95% CI: 0.8, 1.9]. EDVs for pneumonia, COPD, and URTI were also significantly associated with ozone exposure over the whole year, but typically more consistently so during the warm season. Conclusions: Short-term ozone exposures among California residents living near an ozone monitor were positively associated with EDVs for asthma, ARI, pneumonia, COPD, and URTI from 2005 through 2008. Those associations were typically larger and more consistent during the warm season. Our findings suggest that these outcomes should be considered when evaluating the potential health benefits of reducing ozone concentrations. Citation: Malig BJ, Pearson DL, Chang YB, Broadwin R, Basu R, Green RS, Ostro B. 2016. A time-stratified case-crossover study of ambient ozone exposure and emergency department visits for specific respiratory diagnoses in California (2005–2008). Environ Health Perspect 124:745–753; http://dx.doi.org/10.1289/ehp.1409495 PMID:26647366

The impact of induced positive mood on symptomatic behaviour in eating disorders. An experimental, AB/BA crossover design testing a multimodal presentation during a test-meal.

PubMed

Cardi, Valentina; Esposito, Mirko; Clarke, Ariana; Schifano, Sylvia; Treasure, Janet

2015-04-01

The aim of this study was to test the impact of a multimodal positive mood vodcast including pleasant images, background uplifting music and a script designed to elicit positive mood on eating disorders-related symptoms in participants suffering from an Eating Disorder (ED) and healthy controls (HCs). Forty-two women with an ED (Anorexia Nervosa [AN]: N = 19; Bulimia Nervosa [BN]: N = 23) and 36 HCs were included in an AB/BA cross-over design which compared the use of a positive mood induction procedure ("positive mood vodcast") with a control condition (i.e. blue static background, neutral music, and script describing objective facts) during a test-meal. Self-report measures and behavioural tasks were completed before and after the test-meal. The positive mood vodcast was associated with greater consumption of the test meal in the AN group; reduced vigilance to food stimuli and lower anxiety in the BN sample; and no significant changes in the HC group. The use of a positive mood vodcast was associated with some beneficial effects in the context of an experimental test-meal in participants with an ED. Copyright © 2014 Elsevier Ltd. All rights reserved.

Moringa Oleifera leaf extract increases plasma antioxidant status associated with reduced plasma malondialdehyde concentration without hypoglycemia in fasting healthy volunteers.

PubMed

Ngamukote, Sathaporn; Khannongpho, Teerawat; Siriwatanapaiboon, Marent; Sirikwanpong, Sukrit; Dahlan, Winai; Adisakwattana, Sirichai

2016-12-29

To investigate the effect of Moringa Oleifera leaf extract (MOLE) on plasma glucose concentration and antioxidant status in healthy volunteers. A randomized crossover design was used in this study. Healthy volunteers were randomly assigned to receive either 200 mL of warm water (10 cases) or 200 mL of MOLE (500 mg dried extract, 10 cases). Blood samples were drawn at 0, 30, 60, 90, and 120 min for measuring fasting plasma glucose (FPG), ferric reducing ability of plasma (FRAP), Trolox equivalent antioxidant capacity (TEAC) and malondialdehyde (MDA). FPG concentration was not signifificantly different between warm water and MOLE. The consumption of MOLE acutely improved both FRAP and TEAC, with increases after 30 min of 30 μmol/L FeSO 4 equivalents and 0.18 μmol/L Trolox equivalents, respectively. The change in MDA level from baseline was signifificantly lowered after the ingestion of MOLE at 30, 60, and 90 min. In addition, FRAP level was negatively correlated with plasma MDA level after an intake of MOLE. MOLE increased plasma antioxidant capacity without hypoglycemia in human. The consumption of MOLE may reduce the risk factors associated with chronic degenerative diseases.

Tweeting back: predicting new cases of back pain with mass social media data.

PubMed

Lee, Hopin; McAuley, James H; Hübscher, Markus; Allen, Heidi G; Kamper, Steven J; Moseley, G Lorimer

2016-05-01

Back pain is a global health problem. Recent research has shown that risk factors that are proximal to the onset of back pain might be important targets for preventive interventions. Rapid communication through social media might be useful for delivering timely interventions that target proximal risk factors. Identifying individuals who are likely to discuss back pain on Twitter could provide useful information to guide online interventions. We used a case-crossover study design for a sample of 742 028 tweets about back pain to quantify the risks associated with a new tweet about back pain. The odds of tweeting about back pain just after tweeting about selected physical, psychological, and general health factors were 1.83 (95% confidence interval [CI], 1.80-1.85), 1.85 (95% CI: 1.83-1.88), and 1.29 (95% CI, 1.27-1.30), respectively. These findings give directions for future research that could use social media for innovative public health interventions. © The Author 2015. Published by Oxford University Press on behalf of the American Medical Informatics Association. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Crossover from capillary fingering to viscous fingering in a rough fracture

NASA Astrophysics Data System (ADS)

Hu, R.; Chen, Y.; Wu, D. S.

2017-12-01

Controlled by the competition between capillary and viscous forces, the displacement patterns of one fluid displacing another more viscous one exhibit capillary fingering, viscous fingering, and the crossover between the two. Although extensive studies have investigated viscous and capillary fingerings in porous and fractured media, a few studies focused on the crossover in rough fractures, and how viscous and capillary forces affect the crossover remains unclear. Using a transparent fracture visualization system, we studied how the competition impacts the crossover in a horizontal rough fracture. Drainage experiments of water displacing oil were conducted at seven flow rates (capillary number log10Ca ranging from -7.07 to -3.07) and four viscosity ratios (M = 1/1000, 1/500, 1/100 and 1/50). We consistently observed lower invading fluid saturations in the crossover zone. In addition, we proposed a phase diagram for the displacement patterns in a rough fracture that is consistent with similar studies in porous media. Based on real-time imaging and statistical analysis of the invasion morphology, we showed that the competition between the capillary and viscous forces is responsible for the saturation reduction in the crossover zone. In this zone, finger propagation toward the outlet (characteristic of viscous fingering) as well as void-filling in the transverse and backward directions (characteristic of capillary fingering), are both suppressed. Therefore, the invading fluid tends to occupy larger apertures with higher characteristic front velocity, promoting void-filling toward the outlet with thinner finger growth and resulting in a larger volume of defending fluid left behind.

Local potential evolutions during proton exchange membrane fuel cell operation with dead-ended anode - Part I: Impact of water diffusion and nitrogen crossover

NASA Astrophysics Data System (ADS)

Abbou, S.; Dillet, J.; Maranzana, G.; Didierjean, S.; Lottin, O.

2017-02-01

Operating a PEMFC with a dead-ended anode may lead to local fuel-starvation because of water and possibly nitrogen accumulation in the anode compartment. In previous works, we used a segmented linear cell with reference electrodes to monitor simultaneously the local potentials and current densities during dead-ended anode operation. The results indicated that water transport as well as nitrogen crossover through the membrane were most probably the two key factors governing fuel starvation. In this first from a set of two papers, we evaluated with more details the contributions of nitrogen crossover and water transport to hydrogen starvation. To assess nitrogen contribution, the fuel cell cathode compartment was first supplied with pure oxygen instead of air. The results showed that in the absence of nitrogen (in the cathode side) the fuel starvation was much slower than with air, suggesting that nitrogen contribution cannot be neglected. On the other hand, the contribution of water flooding to hydrogen starvation was investigated by using different cooling temperature on the cathode and anode sides in order to drive water toward the colder plate. The results showed that with a colder anode side, fuel starvation was faster. In the opposite case of a hotter anode plate, water accumulation in the anode compartment was limited, nitrogen crossover through the membrane was the main reason for hydrogen starvation in this case. To fully assess the impact of the thermal configurations on membrane-electrode assembly (MEA) degradation, aging protocols with a dead-ended anode and a fixed closing time were also performed. The results showed that operation with a hotter anode could help to limit significantly cathode ElectroChemical Surface Area (ECSA) losses along the cell area and performance degradation induced by hydrogen starvation.

Tail-like regime and BCS-BEC crossover due to hybridization in a two-band superconductor.

PubMed

Reyes, D; Continentino, M A; Deus, F; Thomas, C

2018-05-02

Superconductivity in strongly correlated systems is a remarkable phenomenon that attracts huge interest. The study of this problem is relevant for materials such as the high T c oxides, pnictides and heavy fermions. These systems also have in common the existence of electrons of several orbitals that coexist at a common Fermi surface. In this paper we study the effect of pressure, chemical or applied on multi-band superconductivity. Pressure varies the atomic distances and consequently the overlap of the wave-functions in the crystal. This rearranges the electronic structure that we model including a pressure dependent hybridization between the bands. We consider the case of two-dimensional systems in a square lattice with inverted bands. We study the conditions for obtaining a pressure induced superconductor quantum critical point and show that hybridization, i.e. pressure can induce a Bardeen-Cooper-Schrieffer-Bose-Einstein condensation crossover in multi-band systems even for moderate interactions. We found a tail-like superconductor regime and briefly discuss the influence of the symmetry of the order parameter in the results.

Tail-like regime and BCS-BEC crossover due to hybridization in a two-band superconductor

NASA Astrophysics Data System (ADS)

Reyes, D.; Continentino, M. A.; Deus, F.; Thomas, C.

2018-05-01

Superconductivity in strongly correlated systems is a remarkable phenomenon that attracts huge interest. The study of this problem is relevant for materials such as the high T c oxides, pnictides and heavy fermions. These systems also have in common the existence of electrons of several orbitals that coexist at a common Fermi surface. In this paper we study the effect of pressure, chemical or applied on multi-band superconductivity. Pressure varies the atomic distances and consequently the overlap of the wave-functions in the crystal. This rearranges the electronic structure that we model including a pressure dependent hybridization between the bands. We consider the case of two-dimensional systems in a square lattice with inverted bands. We study the conditions for obtaining a pressure induced superconductor quantum critical point and show that hybridization, i.e. pressure can induce a Bardeen–Cooper–Schrieffer-Bose–Einstein condensation crossover in multi-band systems even for moderate interactions. We found a tail-like superconductor regime and briefly discuss the influence of the symmetry of the order parameter in the results.

Hyperbaric oxygen therapy can improve post concussion syndrome years after mild traumatic brain injury - randomized prospective trial.

PubMed

Boussi-Gross, Rahav; Golan, Haim; Fishlev, Gregori; Bechor, Yair; Volkov, Olga; Bergan, Jacob; Friedman, Mony; Hoofien, Dan; Shlamkovitch, Nathan; Ben-Jacob, Eshel; Efrati, Shai

2013-01-01

Traumatic brain injury (TBI) is the leading cause of death and disability in the US. Approximately 70-90% of the TBI cases are classified as mild, and up to 25% of them will not recover and suffer chronic neurocognitive impairments. The main pathology in these cases involves diffuse brain injuries, which are hard to detect by anatomical imaging yet noticeable in metabolic imaging. The current study tested the effectiveness of Hyperbaric Oxygen Therapy (HBOT) in improving brain function and quality of life in mTBI patients suffering chronic neurocognitive impairments. The trial population included 56 mTBI patients 1-5 years after injury with prolonged post-concussion syndrome (PCS). The HBOT effect was evaluated by means of prospective, randomized, crossover controlled trial: the patients were randomly assigned to treated or crossover groups. Patients in the treated group were evaluated at baseline and following 40 HBOT sessions; patients in the crossover group were evaluated three times: at baseline, following a 2-month control period of no treatment, and following subsequent 2-months of 40 HBOT sessions. The HBOT protocol included 40 treatment sessions (5 days/week), 60 minutes each, with 100% oxygen at 1.5 ATA. "Mindstreams" was used for cognitive evaluations, quality of life (QOL) was evaluated by the EQ-5D, and changes in brain activity were assessed by SPECT imaging. Significant improvements were demonstrated in cognitive function and QOL in both groups following HBOT but no significant improvement was observed following the control period. SPECT imaging revealed elevated brain activity in good agreement with the cognitive improvements. HBOT can induce neuroplasticity leading to repair of chronically impaired brain functions and improved quality of life in mTBI patients with prolonged PCS at late chronic stage. ClinicalTrials.gov NCT00715052.

Spillover and Crossover of Exhaustion and Life Satisfaction among Dual-Earner Parents

ERIC Educational Resources Information Center

Demerouti, Evangelia; Bakker, Arnold B.; Schaufeli, Wilmar B.

2005-01-01

This study integrates spillover research of stress transferring from work to home and crossover research of strains transferring from one spouse to another. A spillover and crossover model was tested among 191 (couples of) dual-earner parents. For both males and females, it was hypothesized that (self-reported and partners' rating of)…

Response-Order Effects in Survey Methods: A Randomized Controlled Crossover Study in the Context of Sport Injury Prevention.

PubMed

Chan, Derwin K; Ivarsson, Andreas; Stenling, Andreas; Yang, Sophie X; Chatzisarantis, Nikos L; Hagger, Martin S

2015-12-01

Consistency tendency is characterized by the propensity for participants responding to subsequent items in a survey consistent with their responses to previous items. This method effect might contaminate the results of sport psychology surveys using cross-sectional design. We present a randomized controlled crossover study examining the effect of consistency tendency on the motivational pathway (i.e., autonomy support → autonomous motivation → intention) of self-determination theory in the context of sport injury prevention. Athletes from Sweden (N = 341) responded to the survey printed in either low interitem distance (IID; consistency tendency likely) or high IID (consistency tendency suppressed) on two separate occasions, with a one-week interim period. Participants were randomly allocated into two groups, and they received the survey of different IID at each occasion. Bayesian structural equation modeling showed that low IID condition had stronger parameter estimates than high IID condition, but the differences were not statistically significant.

Flooding and Clostridium difficile Infection: A Case-Crossover Analysis

PubMed Central

Lin, Cynthia J.; Wade, Timothy J.; Hilborn, Elizabeth D.

2015-01-01

Clostridium difficile is a bacterium that can spread by water. It often causes acute gastrointestinal illness in older adults who are hospitalized and/or receiving antibiotics; however, community-associated infections affecting otherwise healthy individuals have become more commonly reported. A case-crossover study was used to assess emergency room (ER) and outpatient visits for C. difficile infection following flood events in Massachusetts from 2003 through 2007. Exposure status was based on whether or not a flood occurred prior to the case/control date during the following risk periods: 0–6 days, 7–13 days, 14–20 days, and 21–27 days. Fixed-effects logistic regression was used to estimate the risk of diagnosis with C. difficile infection following a flood. There were 129 flood events and 1575 diagnoses of C. difficile infection. Among working age adults (19–64 years), ER and outpatient visits for C. difficile infection were elevated during the 7–13 days following a flood (Odds Ratio, OR = 1.69; 95% Confidence Interval, CI: 0.84, 3.37). This association was more substantial among males (OR = 3.21; 95% CI: 1.01–10.19). Associations during other risk periods were not observed (p < 0.05). Although we were unable to differentiate community-associated versus nosocomial infections, a potential increase in C. difficile infections should be considered as more flooding is projected due to climate change. PMID:26090609

Flooding and Clostridium difficile Infection: A Case-Crossover Analysis.

PubMed

Lin, Cynthia J; Wade, Timothy J; Hilborn, Elizabeth D

2015-06-17

Clostridium difficile is a bacterium that can spread by water. It often causes acute gastrointestinal illness in older adults who are hospitalized and/or receiving antibiotics; however, community-associated infections affecting otherwise healthy individuals have become more commonly reported. A case-crossover study was used to assess emergency room (ER) and outpatient visits for C. difficile infection following flood events in Massachusetts from 2003 through 2007. Exposure status was based on whether or not a flood occurred prior to the case/control date during the following risk periods: 0-6 days, 7-13 days, 14-20 days, and 21-27 days. Fixed-effects logistic regression was used to estimate the risk of diagnosis with C. difficile infection following a flood. There were 129 flood events and 1575 diagnoses of C. difficile infection. Among working age adults (19-64 years), ER and outpatient visits for C. difficile infection were elevated during the 7-13 days following a flood (Odds Ratio, OR = 1.69; 95% Confidence Interval, CI: 0.84, 3.37). This association was more substantial among males (OR = 3.21; 95% CI: 1.01-10.19). Associations during other risk periods were not observed (p < 0.05). Although we were unable to differentiate community-associated versus nosocomial infections, a potential increase in C. difficile infections should be considered as more flooding is projected due to climate change.

Mobile Application vs Paper Pictorial Blood Assessment Chart to Track Menses in Young Women: A Randomized Cross-over Design.

PubMed

Jacobson, Amanda E; Vesely, Sara K; Haamid, Fareeda; Christian-Rancy, Myra; O'Brien, Sarah H

2018-04-01

Heavy menstrual bleeding is a common symptom reported by approximately 30% of women. The Pictorial Blood Assessment Chart (PBAC) score is often used to quantify severity of menstrual bleeding. However, the traditional PBAC paper diary might be subject to recall bias and compliance issues, especially in adolescents. We developed a mobile application (app) version of the PBAC score and evaluated patient satisfaction and compliance with app reporting vs paper reporting. DESIGN, SETTING, PARTICIPANTS, INTERVENTIONS, AND MAIN OUTCOME MEASURES: This study was a randomized cross-over study of 25 postmenarchal female adolescents and young women ages 13-21 years. Participants agreed to track bleeding in 2 consecutive menstrual cycles and were randomized to use the PBAC paper diary or mobile app format first. At the end of each cycle, a satisfaction survey and system usability scale (app only) was used to assess the acceptability of the format used. Twenty-five participants had a median age of 15 years. Cross-over analysis showed that satisfaction level was significantly higher for the app (P < .001). Twenty of 25 (80%) participants preferred the app over the paper diary. For the app, 20 of 25 participants (80%) had high compliance for reporting bleeding, with a mean of 2 app entries per day. Participants' PBAC scores did not vary significantly between the paper diary (median, 95) and mobile app (median, 114). All paper diaries met definition for high compliance. There was no significant period or carryover effect. This study showed that a PBAC app compared with the paper diary was the preferred method of recording menstrual bleeding in adolescents and showed feasibility as a research data collection tool. Copyright © 2017 North American Society for Pediatric and Adolescent Gynecology. Published by Elsevier Inc. All rights reserved.

Target Detection over the Diurnal Cycle Using a Multispectral Infrared Sensor.

PubMed

Zhao, Huijie; Ji, Zheng; Li, Na; Gu, Jianrong; Li, Yansong

2016-12-29

When detecting a target over the diurnal cycle, a conventional infrared thermal sensor might lose the target due to the thermal crossover, which could happen at any time throughout the day when the infrared image contrast between target and background in a scene is indistinguishable due to the temperature variation. In this paper, the benefits of using a multispectral-based infrared sensor over the diurnal cycle have been shown. Firstly, a brief theoretical analysis on how the thermal crossover influences a conventional thermal sensor, within the conditions where the thermal crossover would happen and why the mid-infrared (3~5 μm) multispectral technology is effective, is presented. Furthermore, the effectiveness of this technology is also described and we describe how the prototype design and multispectral technology is employed to help solve the thermal crossover detection problem. Thirdly, several targets are set up outside and imaged in the field experiment over a 24-h period. The experimental results show that the multispectral infrared imaging system can enhance the contrast of the detected images and effectively solve the failure of the conventional infrared sensor during the diurnal cycle, which is of great significance for infrared surveillance applications.

Target Detection over the Diurnal Cycle Using a Multispectral Infrared Sensor

PubMed Central

Zhao, Huijie; Ji, Zheng; Li, Na; Gu, Jianrong; Li, Yansong

2016-01-01

When detecting a target over the diurnal cycle, a conventional infrared thermal sensor might lose the target due to the thermal crossover, which could happen at any time throughout the day when the infrared image contrast between target and background in a scene is indistinguishable due to the temperature variation. In this paper, the benefits of using a multispectral-based infrared sensor over the diurnal cycle have been shown. Firstly, a brief theoretical analysis on how the thermal crossover influences a conventional thermal sensor, within the conditions where the thermal crossover would happen and why the mid-infrared (3~5 μm) multispectral technology is effective, is presented. Furthermore, the effectiveness of this technology is also described and we describe how the prototype design and multispectral technology is employed to help solve the thermal crossover detection problem. Thirdly, several targets are set up outside and imaged in the field experiment over a 24-h period. The experimental results show that the multispectral infrared imaging system can enhance the contrast of the detected images and effectively solve the failure of the conventional infrared sensor during the diurnal cycle, which is of great significance for infrared surveillance applications. PMID:28036073

Peer Assessment Enhances Student Learning: The Results of a Matched Randomized Crossover Experiment in a College Statistics Class.

PubMed

Sun, Dennis L; Harris, Naftali; Walther, Guenther; Baiocchi, Michael

2015-01-01

Feedback has a powerful influence on learning, but it is also expensive to provide. In large classes it may even be impossible for instructors to provide individualized feedback. Peer assessment is one way to provide personalized feedback that scales to large classes. Besides these obvious logistical benefits, it has been conjectured that students also learn from the practice of peer assessment. However, this has never been conclusively demonstrated. Using an online educational platform that we developed, we conducted an in-class matched-set, randomized crossover experiment with high power to detect small effects. We establish that peer assessment causes a small but significant gain in student achievement. Our study also demonstrates the potential of web-based platforms to facilitate the design of high-quality experiments to identify small effects that were previously not detectable.

Limb salvage following iatrogenic arterial injury: complications of cardiac support using intra-aortic balloon pumps.

PubMed

Hunt, Adam; Waldin, Owen; Slim, Hani; Brar, Ranjeet

2016-06-06

This is a unique case report describing complex limb salvage in a patient who experienced acute limb ischaemia due to a complication of intra-aortic balloon pump (IABP) counterpulsation. This case focuses on a patient who had an IABP counterpulsation device inserted following myocardial infarction, requiring urgent coronary artery bypass grafting for acute coronary syndrome. Postoperatively, the IABP could not be removed, with consequent iliac thrombosis and acute limb ischaemia. Emergency femoral-to-femoral crossover bypass was performed using a polytetrafluoroethylene graft. A portion of the IABP balloon tip was entrapped and retained, however, and became the focus of delayed septicaemia, resulting in graft infection and wound breakdown 6 weeks later. Explantation of the residual balloon tip, ligation of the right external iliac artery and redo femoral-femoral crossover using the great saphenous vein were successfully performed. 2016 BMJ Publishing Group Ltd.

Association between outdoor ozone and compensated acute respiratory diseases among workers in Quebec (Canada).

PubMed

Adam-Poupart, Ariane; Labrèche, France; Busque, Marc-Antoine; Brand, Allan; Duguay, Patrice; Fournier, Michel; Zayed, Joseph; Smargiassi, Audrey

2015-01-01

Respiratory effects of ozone in the workplace have not been extensively studied. Our aim was to explore the relationship between daily average ozone levels and compensated acute respiratory problems among workers in Quebec between 2003 and 2010 using a time-stratified case-crossover design. Health data came from the Workers' Compensation Board. Daily concentrations of ozone were estimated using a spatiotemporal model. Conditional logistic regressions, with and without adjustment for temperature, were used to estimate odds ratios (ORs, per 1 ppb increase of ozone), and lag effects were assessed. Relationships with respiratory compensations in all industrial sectors were essentially null. Positive non-statistically significant associations were observed for outdoor sectors, and decreased after controlling for temperature (ORs of 0.98; 1.01 and 1.05 at Lags 0, 1 and 2 respectively). Considering the predicted increase of air pollutant concentrations in the context of climate change, closer investigation should be carried out on outdoor workers.

The Effects of Particulate Matter Sources on Daily Mortality: A Case-Crossover Study of Barcelona, Spain

PubMed Central

Tobias, Aurelio; Querol, Xavier; Alastuey, Andrés; Amato, Fulvio; Pey, Jorge; Pérez, Noemí; Sunyer, Jordi

2011-01-01

Background: Dozens of studies link acute exposure to particulate matter (PM) air pollution with premature mortality and morbidity, but questions remain about which species and sources in the vast PM mixture are responsible for the observed health effects. Although a few studies exist on the effects of species and sources in U.S. cities, European cities—which have a higher proportion of diesel engines and denser urban populations—have not been well characterized. Information on the effects of specific sources could aid in targeting pollution control and in articulating the biological mechanisms of PM. Objectives: Our study examined the effects of various PM sources on daily mortality for 2003 through 2007 in Barcelona, a densely populated city in the northeast corner of Spain. Methods: Source apportionment for PM ≤ 2.5 μm and ≤ 10 µm in aerodynamic diameter (PM2.5 and PM10) using positive matrix factorization identified eight different factors. Case-crossover regression analysis was used to estimate the effects of each factor. Results: Several sources of PM2.5, including vehicle exhaust, fuel oil combustion, secondary nitrate/organics, minerals, secondary sulfate/organics, and road dust, had statistically significant associations (p < 0.05) with all-cause and cardiovascular mortality. Also, in some cases relative risks for a respective interquartile range increase in concentration were higher for specific sources than for total PM2.5 mass. Conclusions: These results along with those from our multisource models suggest that traffic, sulfate from shipping and long-range transport, and construction dust are important contributors to the adverse health effects linked to PM. PMID:21846610

Title: Studies on drug switchability showed heterogeneity in methodological approaches: a scoping review.

PubMed

Belleudi, Valeria; Trotta, Francesco; Vecchi, Simona; Amato, Laura; Addis, Antonio; Davoli, Marina

2018-05-16

Several drugs share the same therapeutic indication, including those undergoing patent expiration. Concerns on the interchangeability are frequent in clinical practice, challenging the evaluation of switchability through observational research. To conduct a scoping review of observational studies on drug switchability to identify methodological strategies adopted to deal with bias and confounding. We searched PubMed, EMBASE, and Web of Science (updated 1/31/2017) to identify studies evaluating switchability in terms of effectiveness/safety outcomes or compliance. Three reviewers independently screened studies extracting all characteristics. Strategies to address confounding, particularly, previous drug use and switching reasons were considered. All findings were summarized in descriptive analyses. Thirty-two studies, published in the last 10 years, met the inclusion criteria. Epilepsy, cardiovascular and rheumatology were the most frequently represented clinical areas. 75% of the studies reported data on effectiveness/safety outcomes. The most frequent study design was cohort (65.6%) followed by case-control (21.9%) and self-controlled (12.5%). Case-control and case-crossover studies showed homogeneous methodological strategies to deal with bias and confounding. Among cohort studies, the confounding associated with previous drug use was addressed introducing variables in multivariate model (47.3%) or selecting only adherent patients (14.3%). Around 30% of cohort studies did not report reasons for switching. In the remaining 70%, clinical parameters or previous occurrence of outcomes were measured to identify switching connected with lack of effectiveness or adverse events. This study represents a starting point for researchers and administrators who are approaching the investigation and assessment of issues related to interchangeability of drugs. Copyright © 2018. Published by Elsevier Inc.

Effect of intravenous or oral sodium chlorate administration on the fecal shedding of Escherichia coli in sheep

USDA-ARS?s Scientific Manuscript database

The effect of gavage or intravenous (i.v.) administration of sodium chlorate salts on the fecal shedding of generic Escherichia coli in wether lambs was studied. To this end, 9 lambs (27 +/- 2.5 kg) were administered 150 mg NaClO3 per kg BW by gavage or i.v. infusion in a cross-over design with sal...

The impact of heat on mortality and morbidity in the Greater Metropolitan Sydney Region: a case crossover analysis.

PubMed

Wilson, Leigh Ann; Morgan, Geoffrey Gerard; Hanigan, Ivan Charles; Johnston, Fay H; Abu-Rayya, Hisham; Broome, Richard; Gaskin, Clive; Jalaludin, Bin

2013-11-15

This study examined the association between unusually high temperature and daily mortality (1997-2007) and hospital admissions (1997-2010) in the Sydney Greater Metropolitan Region (GMR) to assist in the development of targeted health programs designed to minimise the public health impact of extreme heat. Sydney GMR was categorized into five climate zones. Heat-events were defined as severe or extreme. Using a time-stratified case-crossover design with a conditional logistic regression model we adjusted for influenza epidemics, public holidays, and climate zone. Odds ratios (OR) and 95% confidence intervals were estimated for associations between daily mortality and hospital admissions with heat-event days compared to non-heat event days for single and three day heat-events. All-cause mortality overall had similar magnitude associations with single day and three day extreme and severe events as did all cardiovascular mortality. Respiratory mortality was associated with single day and three day severe events (95th percentile, lag0: OR = 1.14; 95%CI: 1.04 to 1.24). Diabetes mortality had similar magnitude associations with single day and three day severe events (95th percentile, lag0: OR = 1.22; 95%CI: 1.03 to 1.46) but was not associated with extreme events. Hospital admissions for heat related injuries, dehydration, and other fluid disorders were associated with single day and three day extreme and severe events. Contrary to our findings for mortality, we found inconsistent and sometimes inverse associations for extreme and severe events with cardiovascular disease and respiratory disease hospital admissions. Controlling for air pollutants did not influence the mortality associations but reduced the magnitude of the associations with hospital admissions particularly for ozone and respiratory disease. Single and three day events of unusually high temperatures in Sydney are associated with similar magnitude increases in mortality and hospital admissions. The trend towards an inverse association between cardio-vascular admissions and heat-events and the strong positive association between cardio-vascular mortality and heat-events suggests these events may lead to a rapid deterioration in persons with existing cardio-vascular disease resulting in death. To reduce the adverse effects of high temperatures over multiple days, and less extreme but more frequent temperatures over single days, targeted public health messages are critical.

The impact of heat on mortality and morbidity in the Greater Metropolitan Sydney Region: a case crossover analysis

PubMed Central

2013-01-01

Background This study examined the association between unusually high temperature and daily mortality (1997–2007) and hospital admissions (1997–2010) in the Sydney Greater Metropolitan Region (GMR) to assist in the development of targeted health programs designed to minimise the public health impact of extreme heat. Methods Sydney GMR was categorized into five climate zones. Heat-events were defined as severe or extreme. Using a time-stratified case-crossover design with a conditional logistic regression model we adjusted for influenza epidemics, public holidays, and climate zone. Odds ratios (OR) and 95% confidence intervals were estimated for associations between daily mortality and hospital admissions with heat-event days compared to non-heat event days for single and three day heat-events. Results All-cause mortality overall had similar magnitude associations with single day and three day extreme and severe events as did all cardiovascular mortality. Respiratory mortality was associated with single day and three day severe events (95thpercentile, lag0: OR = 1.14; 95%CI: 1.04 to 1.24). Diabetes mortality had similar magnitude associations with single day and three day severe events (95thpercentile, lag0: OR = 1.22; 95%CI: 1.03 to 1.46) but was not associated with extreme events. Hospital admissions for heat related injuries, dehydration, and other fluid disorders were associated with single day and three day extreme and severe events. Contrary to our findings for mortality, we found inconsistent and sometimes inverse associations for extreme and severe events with cardiovascular disease and respiratory disease hospital admissions. Controlling for air pollutants did not influence the mortality associations but reduced the magnitude of the associations with hospital admissions particularly for ozone and respiratory disease. Conclusions Single and three day events of unusually high temperatures in Sydney are associated with similar magnitude increases in mortality and hospital admissions. The trend towards an inverse association between cardio-vascular admissions and heat-events and the strong positive association between cardio-vascular mortality and heat-events suggests these events may lead to a rapid deterioration in persons with existing cardio-vascular disease resulting in death. To reduce the adverse effects of high temperatures over multiple days, and less extreme but more frequent temperatures over single days, targeted public health messages are critical. PMID:24238064

The effects of the DDS-1 strain of lactobacillus on symptomatic relief for lactose intolerance - a randomized, double-blind, placebo-controlled, crossover clinical trial.

PubMed

Pakdaman, Michael N; Udani, Jay K; Molina, Jhanna Pamela; Shahani, Michael

2016-05-20

Lactose intolerance is a form of lactose maldigestion where individuals experience symptoms such as diarrhea, abdominal cramping, flatulence, vomiting and bowel sounds following lactose consumption. Lactobacillus acidophilus is a species of bacteria known for its sugar fermenting properties. Preclinical studies have found that Lactobacillus acidophilus supplementation may assist in breaking down lactose; however, no human clinical trials exist evaluating its efficacy in alleviating symptoms related to lactose intolerance. The aim of this randomized, double-blind, placebo-controlled, crossover study was to evaluate the effect of a proprietary strain of Lactobacillus acidophilus on relieving discomfort related to lactose intolerance. The study enrolled healthy volunteers between 18 and 75 years of age who complained of lactose intolerance. Screening visits included a lactose challenge visit to confirm eligibility based on a score of 10 or higher on subjective assessment of the following symptoms after lactose challenge: diarrhea, abdominal cramping, vomiting, audible bowel sounds, flatulence, and overall symptoms. Qualified subjects participated in a 2-arm crossover design, with each arm consisting of 4 weeks of intervention of either active or placebo product, with a 2-week washout period during crossover. The study product consisted of the DDS-1 strain of Lactobacillus acidophilus (Nebraska Cultures, Walnut Creek, California). The placebo was formulated from maltodextrin. Study participants were instructed to take the product once daily for 4 weeks. Data collected included subjective symptom scores related to lactose intolerance. Longitudinal comparison between the DDS-1 group and placebo group demonstrated statistically significant reductions in abdominal symptom scores during the 6-h Lactose Challenge at week 4 for diarrhea (p = 0.033), abdominal cramping (p = 0.012), vomiting (p = 0.0002), and overall symptom score (p = 0.037). No adverse events were reported. The present study has found that this unique DDS-1 strain of Lactobacillus acidophilus, manufactured by Nebraska Cultures, is safe to consume and improves abdominal symptom scores compared to placebo with respect to diarrhea, cramping, and vomiting during an acute lactose challenge.

Bisphosphonate therapy start may transiently increase the risk of tendon rupture in patients with glucocorticoid co-medication: a population-based observational study.

PubMed

Spoendlin, Julia; Meier, Christian; Jick, Susan S; Meier, Christoph R

2016-10-01

The effect of bisphosphonates on extra-osseous tissue is rarely investigated. We performed an exploratory analysis on the association of new bisphosphonate use and incident tendon rupture in patients with or without oral glucocorticoid co-medication. We conducted a matched case-control study using data from the UK-based Clinical Practice Research Datalink. Cases were patients aged 30-89 years with an incident diagnosis of Achilles or biceps tendon rupture between 1995 and 2013. We compared new oral bisphosphonate use between cases and controls with or without oral glucocorticoid co-medication, by timing (last prescription

Visualizing and quantifying the crossover from capillary fingering to viscous fingering in a rough fracture

NASA Astrophysics Data System (ADS)

Chen, Yi-Feng; Fang, Shu; Wu, Dong-Sheng; Hu, Ran

2017-09-01

Immiscible fluid-fluid displacement in permeable media is important in many subsurface processes, including enhanced oil recovery and geological CO2 sequestration. Controlled by capillary and viscous forces, displacement patterns of one fluid displacing another more viscous one exhibit capillary and viscous fingering, and crossover between the two. Although extensive studies investigated viscous and capillary fingering in porous media, a few studies focused on the crossover in rough fractures, and how viscous and capillary forces affect the crossover remains unclear. Using a transparent fracture-visualization system, we studied how the two forces impact the crossover in a horizontal rough fracture. Drainage experiments of water displacing oil were conducted at seven flow rates (capillary number log10Ca ranging from -7.07 to -3.07) and four viscosity ratios (M=1/1000,1/500,1/100 and 1/50). We consistently observed lower invading fluid saturations in the crossover zone. We also proposed a phase diagram for the displacement patterns in a rough fracture that is consistent with similar studies in porous media. Based on real-time imaging and statistical analysis of the invasion morphology, we showed that the competition between capillary and viscous forces is responsible for the saturation reduction in the crossover zone. In this zone, finger propagation toward the outlet (characteristic of viscous fingering) as well as void-filling in the transverse/backward directions (characteristic of capillary fingering), are both suppressed. Therefore, the invading fluid tends to occupy larger apertures with higher characteristic front velocity, promoting void-filling toward the outlet with thinner finger growth and resulting in a larger volume of defending fluid left behind.

Effect of Persian Medicine Remedy on Chemotherapy Induced Nausea and Vomiting in Breast Cancer: A Double Blind, Randomized, Crossover Clinical Trial

PubMed Central

Nazari, Mohammad; Taghizadeh, Ali; Bazzaz, Mojtaba Mousavi; Rakhshandeh, Hassan; Shokri, Sadegh

2017-01-01

Background Chemotherapy induced nausea and vomiting (CINV) is a side effect, and has negative effect on quality of life and continuation of chemotherapy. Despite new regimen and drugs, the problems still remain and standard guidelines, effective treatment and supportive care for refractory CINV are still not yet established. Persian medicine, the old Iranian medical school, offer Persumac (prepared from Rhus Coriaria and Bunium Persicum Boiss). Objective The specific objectives were to assess the effect of Persumac on the number and severity of nausea and vomiting in refractory CINV in acute and delayed phase. Methods This randomized, double blind, crossover clinical trial study was carried out on 93 patients with breast cancer and refractory CINV, who received outpatient high emetogenic chemotherapy in Imam Reza hospital, Mashhad, Iran from October 2015 to May 2016. The study has three stages: in stage I patients received a questionaire and completed it after chemotherapy. In stage II they were randomly divided into intervention group with Persumac and control group with placebo (lactose were used). In stage III, wash out and crossover was conducted. Both groups in all stages received standard antiemetic therapy for CINV. The following were set as the inclusion criteria of the study: female, Age ≥18 years, clinical diagnosis of breast cancer, history of refractory CINV, normal blood tests and at least three courses of chemotherapy remaining. Exclusion criteria of this study were: Total or upper abdominal radiation therapy along with chemotherapy, drugs/therapy for nausea and vomiting not prescribed in this study, hypersensitivity to Sumac or Bunium Persicum, use of sumac and Bunium Persicum in seven days prior to the intervention, clinical diagnosis of digestion disorders, non-chemotherapy induced nausea and vomiting, milk allergy, loss of two consecutive or three intermittent doses of Persumac or placebo. Outcomes were gathered by Persian questionnaire. Number and severity of nausea and vomiting was measured with a self-reporting tool; visual analog scale. Results Demographic data and other characters in both groups have no significant diffrence. Eighty of 93 eligible patients in stage I completed the study and in stage II, eleven declined participation for stage III (crossover). P value of carry over, period and treatment effects demonstrated that they had not affected the results before and after crossover. The mean severity of nausea in acute phase was in stage I: 4.83 ± 1.40, stage II: 4.54 ± 2.0 and stage III: 4.15 ± 0.92 in sequence AB (first Persumac and then placebo in crossover), and in sequence BA (first placebo and then Persumac in crossover) was respectively 4.83 ± 1.40, 4.54 ± 2.0, 4.15 ± 0.92 with p value of carry over effect: 0.03 and period effect: 0.22. Except for severity of nausea in acute phase, the mean number and severity of nausea and vomiting scores significantly decreased in acute and delayed phase of CINV. Conclusion Persumac may control the refractory CINV. The implicable and clinical importance of this research is that another option exists for refractory CINV. Higher doses, different cancers, patients with more various features, and more complete methodology and tools can provide appropriate designs for new research on this topic. Trial registration This trial was registered at the Clinical Trials.gov ID: NCT02787707. Funding This study is part of a Ph.D. thesis and under grant; No: 930735 of Research Chancellery of MUMS. PMID:28243404

Structural, thermal, and magnetic study of solvation processes in spin-crossover [Fe(bpp)(2)][Cr(L)(ox)(2)](2).nH(2)O complexes.

PubMed

Clemente-León, Miguel; Coronado, Eugenio; Giménez-López, M Carmen; Romero, Francisco M

2007-12-24

The influence of lattice water in the magnetic properties of spin-crossover [Fe(bpp)2]X2.nH2O salts [bpp = 2,6-bis(pyrazol-3-yl)pyridine] is well-documented. In most cases, it stabilizes the low-spin state compared to the anhydrous compound. In other cases, it is rather the contrary. Unraveling this mystery implies the study of the microscopic changes that accompany the loss of water. This might be difficult from an experimental point of view. Our strategy is to focus on some salts that undergo a nonreversible dehydration-hydration process without loss of crystallinity. By comparison of the structural and magnetic properties of original and rehydrated samples, several rules concerning the role of water at the microscopic level can be deduced. This paper reports on the crystal structure, thermal studies, and magnetic properties of [Fe(bpp)2][Cr(bpy)(ox)2]2.2H2O (1), [Fe(bpp)2][Cr(phen)(ox)2]2.0.5H2O.0.5MeOH (2), and [Fe(bpp)2][Cr(phen)(ox)2]2.5.5H2O.2.5MeOH (3). Salt 1 contains both high-spin (HS) and low-spin (LS) Fe2+ cations in a 1:1 ratio. Dehydration yields the anhydrous spin-crossover compound with T1/2 downward arrow = 353 K and T1/2 upward arrow = 369 K. Rehydration affords the dihydrate [Fe(bpp)2][Cr(bpy)(ox)2]2.2H2O (1r) with 100% HS Fe2+ sites. Salt 2 also contains both HS and LS Fe2+ cations in a 1:1 ratio. Dehydration yields the anhydrous spin-crossover compound with T1/2 downward arrow = 343 K and T1/2 upward arrow = 348 K. Rehydration affords [Fe(bpp)2][Cr(phen)(ox)2]2.0.5H2O (2r) with 72% Fe2+ sites in the LS configuration. The structural, magnetic, and thermal properties of these rehydrated compounds 1r and 2r are also discussed. Finally, 1 has been dehydrated and resolvated with MeOH to give [Fe(bpp)2][Cr(bpy)(ox)2]2.MeOH (1s) with 33% HS Fe2+ sites. The influence of the guest solvent in the Fe2+ spin state can anticipate the future applications of these compounds in solvent sensing.

Dielectrophoretic spectroscopy using a microscopic electrode array

NASA Astrophysics Data System (ADS)

Kirmani, Syed Abdul Mannan; Gudagunti, Fleming Dackson; Velmanickam, Logeeshan; Nawarathna, Dharmakeerthi; Lima, Ivan T.

2017-02-01

Dielectrophoresis (DEP) is a commonly used technique in biomedical engineering to manipulate biomolecules. DEP is defined as the force acting on dielectric particles when they are exposed to non-uniform electric fields. DEP effect can be divided in three categories: positive (dielectric particles are attracted to the electrodes), negative, and zero force DEP. The cross-over frequency is the frequency in which the DEP force is equal to zero. The cross-over frequency depends on the conductivity and the permittivity of the particles and of the suspended medium. The DEP cross-over frequency has been utilized in detecting/quantifying biomolecules. A manual procedure is commonly used to estimate the cross-over frequency of biomolecules. Therefore, the accuracy of this detection method is significantly limited. To address this issue, we designed and tested an automated procedure to carry out DEP spectroscopy in dielectric particles dissolved in a biological buffer solution. Our method efficiently measures the effect of the DEP force through a live video feed from the microscope camera and performs real-time image processing. It records the change in the fluorescence emission as the system automatically scans the electric frequency of the function generator over a specified time interval. We demonstrated the effectiveness of the method by extracting the crossover frequencies and the DEP spectrum of polystyrene beads with blue color dye (1000 nm diameter) and green fluorescent polystyrene beads with 500 nm diameter using this procedure. This approach can lead to the development of a biosensor with significantly higher sensitivity than existing detection methods.

Does case misclassification threaten the validity of studies investigating the relationship between neck manipulation and vertebral artery dissection stroke? No.

PubMed

Murphy, Donald R; Schneider, Michael J; Perle, Stephen M; Bise, Christopher G; Timko, Michael; Haas, Mitchell

2016-01-01

The purported relationship between cervical manipulative therapy (CMT) and stroke related to vertebral artery dissection (VAD) has been debated for several decades. A large number of publications, from case reports to case-control studies, have investigated this relationship. A recent article suggested that case misclassification in the case-control studies on this topic resulted in biased odds ratios in those studies. Given its rarity, the best epidemiologic research design for investigating the relationship between CMT and VAD is the case-control study. The addition of a case-crossover aspect further strengthens the scientific rigor of such studies by reducing bias. The most recent studies investigating the relationship between CMT and VAD indicate that the relationship is not causal. In fact, a comparable relationship between vertebral artery-related stroke and visits to a primary care physician has been observed. The statistical association between visits to chiropractors and VAD can best be explained as resulting from a patient with early manifestation of VAD (neck pain with or without headache) seeking the services of a chiropractor for relief of this pain. Sometime after the visit the patient experiences VAD-related stroke that would have occurred regardless of the care received. This explanation has been challenged by a recent article putting forth the argument that case misclassification is likely to have biased the odds ratios of the case-control studies that have investigated the association between CMT and vertebral artery related stroke. The challenge particularly focused on one of the case-control studies, which had concluded that the association between CMT and vertebral artery related stroke was not causal. It was suggested by the authors of the recent article that misclassification led to an underestimation of risk. We argue that the information presented in that article does not support the authors' claim for a variety of reasons, including the fact that the assumptions upon which their analysis is based lack substantiation and the fact that any possible misclassification would not have changed the conclusion of the study in question. Current evidence does not support the notion that misclassification threatens the validity of recent case-control studies investigating the relationship between CMT and VAD. Hence, the recent re-analysis cannot refute the conclusion from previous studies that CMT is not a cause of VAD.

Using a Montessori method to increase eating ability for institutionalised residents with dementia: a crossover design.

PubMed

Lin, Li-Chan; Huang, Ya-Ju; Watson, Roger; Wu, Shiao-Chi; Lee, Yue-Chune

2011-11-01

To investigate the efficacy of applying a Montessori intervention to improve the eating ability and nutritional status of residents with dementia in long-term care facilities. An early intervention for eating difficulties in patients with dementia can give them a better chance of maintaining independence and reduce the risk of malnutrition. An experimental crossover design was employed. Twenty-nine residents were chosen from two dementia special care units in metropolitan Taipei. To avoid contamination between participants in units using both Montessori and control interventions, two dementia special care units were randomly assigned into Montessori intervention (I1) and routine activities (I2) sequence groups. A two-period crossover design was used, with 15 residents assigned to Montessori intervention sequence I (I1, I2) and 14 residents assigned to Montessori intervention sequence II (I2, I1). On each intervention day, residents were given their assigned intervention. Montessori intervention was provided in 30-min sessions once every day, three days per week, for eight weeks. There was a two-week washout period between each intervention. There was a significant reduction in the Edinburgh Feeding Evaluation in Dementia score for the Montessori intervention period but not for the routine activities period, while the mean differences for the Eating Behavior Scale score, self-feeding frequency and self-feeding time were significantly higher than those of the routine activities period. Except for the Mini-Nutritional Assessment score post-test being significantly less than the pre-test for the routine activities period, no significant differences for any other variables were found for the routine activities period. This study confirms the efficacy of a Montessori intervention protocol on eating ability of residents with dementia. Adopting Montessori intervention protocols to maintain residents' self-feeding ability in clinical practice is recommended. Montessori-based activities could provide caregivers with an evidence-based nursing strategy to deal with eating difficulties of people with dementia. © 2011 Blackwell Publishing Ltd.

Residual effects of middle-of-the-night administration of zaleplon and zolpidem on driving ability, memory functions, and psychomotor performance.

PubMed

Verster, Joris C; Volkerts, Edmund R; Schreuder, Antonia H C M L; Eijken, Erik J E; van Heuckelum, Janet H G; Veldhuijzen, Dieuwke S; Verbaten, Marinus N; Paty, Isabelle; Darwish, Mona; Danjou, Philippe; Patat, Alain

2002-12-01

Thirty healthy volunteers participated in this two-part study. Part 1 was a single-blind, two-period crossover design to determine the effects of a single dose of ethanol (0.03% < BAC < 0.05%) or ethanol-placebo on driving ability, memory, and psychomotor performance. Part 2 was a double-blind, five-period crossover design to measure the effects of a middle-of-the-night administration of zaleplon 10 or 20 mg, zolpidem 10 or 20 mg, or placebo on driving ability 4 hours after administration and memory and psychomotor performance 6 hours after administration. The on-the-road driving test consisted of operating an instrumented automobile over a 100-km highway circuit at a constant speed (95 km/h) while maintaining a steady lateral position between the right lane boundaries. The standard deviation of lateral position (SDLP) was the primary performance parameter of the driving test. The psychomotor and memory test battery consisted of the Word Learning Test, the Critical Tracking Test, the Divided Attention Test, and the Digit Symbol Substitution Test. Data for each part were analyzed separately using ANOVA for crossover designs. Zaleplon 10 and 20 mg did not significantly impair driving ability 4 hours after middle-of-the-night administration. Relative to placebo, after zolpidem 10 mg, SDLP was significantly elevated, but the magnitude of the difference was small and not likely to be of clinical importance. Memory and psychomotor test performance was unaffected after both doses of zaleplon and zolpidem 10 mg. In contrast, zolpidem 20 mg significantly increased SDLP and speed variability. Further, zolpidem 20 mg significantly impaired performance on all psychomotor and memory tests. Finally, driving performance, Digit Symbol Substitution Test, Divided Attention Test, and immediate and delayed free recall of the Word Learning Test were significantly impaired after ethanol. The results show that zaleplon (10 and 20 mg) is a safe hypnotic devoid of next-morning residual impairment when used in the middle of the night.

Genetic algorithm with maximum-minimum crossover (GA-MMC) applied in optimization of radiation pattern control of phased-array radars for rocket tracking systems.

PubMed

Silva, Leonardo W T; Barros, Vitor F; Silva, Sandro G

2014-08-18

In launching operations, Rocket Tracking Systems (RTS) process the trajectory data obtained by radar sensors. In order to improve functionality and maintenance, radars can be upgraded by replacing antennas with parabolic reflectors (PRs) with phased arrays (PAs). These arrays enable the electronic control of the radiation pattern by adjusting the signal supplied to each radiating element. However, in projects of phased array radars (PARs), the modeling of the problem is subject to various combinations of excitation signals producing a complex optimization problem. In this case, it is possible to calculate the problem solutions with optimization methods such as genetic algorithms (GAs). For this, the Genetic Algorithm with Maximum-Minimum Crossover (GA-MMC) method was developed to control the radiation pattern of PAs. The GA-MMC uses a reconfigurable algorithm with multiple objectives, differentiated coding and a new crossover genetic operator. This operator has a different approach from the conventional one, because it performs the crossover of the fittest individuals with the least fit individuals in order to enhance the genetic diversity. Thus, GA-MMC was successful in more than 90% of the tests for each application, increased the fitness of the final population by more than 20% and reduced the premature convergence.

Genetic Algorithm with Maximum-Minimum Crossover (GA-MMC) Applied in Optimization of Radiation Pattern Control of Phased-Array Radars for Rocket Tracking Systems

PubMed Central

Silva, Leonardo W. T.; Barros, Vitor F.; Silva, Sandro G.

2014-01-01

In launching operations, Rocket Tracking Systems (RTS) process the trajectory data obtained by radar sensors. In order to improve functionality and maintenance, radars can be upgraded by replacing antennas with parabolic reflectors (PRs) with phased arrays (PAs). These arrays enable the electronic control of the radiation pattern by adjusting the signal supplied to each radiating element. However, in projects of phased array radars (PARs), the modeling of the problem is subject to various combinations of excitation signals producing a complex optimization problem. In this case, it is possible to calculate the problem solutions with optimization methods such as genetic algorithms (GAs). For this, the Genetic Algorithm with Maximum-Minimum Crossover (GA-MMC) method was developed to control the radiation pattern of PAs. The GA-MMC uses a reconfigurable algorithm with multiple objectives, differentiated coding and a new crossover genetic operator. This operator has a different approach from the conventional one, because it performs the crossover of the fittest individuals with the least fit individuals in order to enhance the genetic diversity. Thus, GA-MMC was successful in more than 90% of the tests for each application, increased the fitness of the final population by more than 20% and reduced the premature convergence. PMID:25196013

Tuning the metal-insulator crossover and magnetism in SrRuO 3 by ionic gating

DOE PAGES

Yi, Hee Taek; Gao, Bin; Xie, Wei; ...

2014-10-13

Reversible control of charge transport and magnetic properties without degradation is a key for device applications of transition metal oxides. Chemical doping during the growth of transition metal oxides can result in large changes in physical properties, but in most of the cases irreversibility is an inevitable constraint. We report a reversible control of charge transport, metal-insulator crossover and magnetism in field-effect devices based on ionically gated archetypal oxide system - SrRuO 3. In these thin-film devices, the metal-insulator crossover temperature and the onset of magnetoresistance can be continuously and reversibly tuned in the range 90–250 K and 70–100 K,more » respectively, by application of a small gate voltage. We infer that a reversible diffusion of oxygen ions in the oxide lattice dominates the response of these materials to the gate electric field. These findings provide critical insights into both the understanding of ionically gated oxides and the development of novel applications.« less

Tuning the metal-insulator crossover and magnetism in SrRuO₃ by ionic gating.

PubMed

Yi, Hee Taek; Gao, Bin; Xie, Wei; Cheong, Sang-Wook; Podzorov, Vitaly

2014-10-13

Reversible control of charge transport and magnetic properties without degradation is a key for device applications of transition metal oxides. Chemical doping during the growth of transition metal oxides can result in large changes in physical properties, but in most of the cases irreversibility is an inevitable constraint. Here we report a reversible control of charge transport, metal-insulator crossover and magnetism in field-effect devices based on ionically gated archetypal oxide system - SrRuO₃. In these thin-film devices, the metal-insulator crossover temperature and the onset of magnetoresistance can be continuously and reversibly tuned in the range 90-250 K and 70-100 K, respectively, by application of a small gate voltage. We infer that a reversible diffusion of oxygen ions in the oxide lattice dominates the response of these materials to the gate electric field. These findings provide critical insights into both the understanding of ionically gated oxides and the development of novel applications.

NON-HOMOGENEOUS POISSON PROCESS MODEL FOR GENETIC CROSSOVER INTERFERENCE.

PubMed

Leu, Szu-Yun; Sen, Pranab K

2014-01-01

The genetic crossover interference is usually modeled with a stationary renewal process to construct the genetic map. We propose two non-homogeneous, also dependent, Poisson process models applied to the known physical map. The crossover process is assumed to start from an origin and to occur sequentially along the chromosome. The increment rate depends on the position of the markers and the number of crossover events occurring between the origin and the markers. We show how to obtain parameter estimates for the process and use simulation studies and real Drosophila data to examine the performance of the proposed models.

The Effect of School Uniform on Incidental Physical Activity among 10-Year-Old Children

ERIC Educational Resources Information Center

Norrish, Hannah; Farringdon, Fiona; Bulsara, Max; Hands, Beth

2012-01-01

The school setting provides a unique opportunity to promote physical activity in children by ensuring adequate time, appropriate facilities and education guidance is offered. However school uniform design could also limit physical activity. A repeated measures crossover design was used to compare school recess and lunchtime physical activity over…

Behavioral and cognitive effect of theophylline: a dose-response study.

PubMed

Stein, M A; Lerner, C A

1993-02-01

The behavioral and cognitive effects of theophylline were studied in 14 asymptomatic asthmatic children. A double-blind crossover design was used with two dosage levels. Conners parent ratings suggest behavioral improvement by the second week of treatment, regardless of dosage or order of administration. No effects were found on cognitive measures. We conclude that the majority of behavior problems associated with theophylline occur during the induction phase, and that for most children behavior and attention problems rapidly return to baseline or improve.

Efficacy and safety of creatine supplementation in juvenile dermatomyositis: A randomized, double-blind, placebo-controlled crossover trial.

PubMed

Solis, Marina Yazigi; Hayashi, Ana Paula; Artioli, Guilherme Giannini; Roschel, Hamilton; Sapienza, Marcelo Tatit; Otaduy, Maria Concepción; De Sã Pinto, Ana Lucia; Silva, Clovis Artur; Sallum, Adriana Maluf Elias; Pereira, Rosa Maria R; Gualano, Bruno

2016-01-01

It has been suggested that creatine supplementation is safe and effective for treating idiopathic inflammatory myopathies, but no pediatric study has been conducted to date. The objective of this study was to examine the efficacy and safety of creatine supplementation in juvenile dermatomyositis (JDM) patients. In this study, JDM patients received placebo or creatine supplementation (0.1 g/kg/day) in a randomized, crossover, double-blind design. Subjects were assessed at baseline and after 12 weeks. The primary outcome was muscle function. Secondary outcomes included body composition, aerobic conditioning, health-related quality of life, and muscle phosphocreatine (PCr) content. Safety was assessed by laboratory parameters and kidney function measurements. Creatine supplementation did not affect muscle function, intramuscular PCr content, or any other secondary outcome. Kidney function was not affected, and no side effects were reported. Twelve weeks of creatine supplementation in JDM patients were well-tolerated and free of adverse effects, but treatment did not affect muscle function, intramuscular PCr, or any other parameter. © 2015 Wiley Periodicals, Inc.

Medication use and the risk of motor vehicle collision in West Virginia drivers 65 years of age and older: a case-crossover study.

PubMed

Rudisill, Toni M; Zhu, Motao; Davidov, Danielle; Leann Long, D; Sambamoorthi, Usha; Abate, Marie; Delagarza, Vincent

2016-03-15

The current generation of older adults reports a higher lifetime prevalence of prescription, over-the-counter, and recreational drug use. The purpose of this analysis is to characterize the drug usage and determine the risk of motor vehicle collision associated with individual medications in a population of drivers ≥ 65 years. A case-crossover study was conducted at West Virginia University Healthcare's facilities using data obtained from the electronic health records (n = 611) of drivers ≥ 65 years admitted for medical treatment following a motor vehicle collision which occurred between Jan. 1, 2009 and June 30, 2014. Patients' medication usage 14 days before collision were matched and compared to their medication usage during four control periods prior to collision. Odds ratios were then calculated for the most prevalent individual medications and pharmaceutical sub-classes using conditional logistic regression. Analgesic, cardiovascular and gastrointestinal medicines were common. Few drivers tested positive for either licit or illicit drugs. Of those testing positive for drugs, benzodiazepines and opiates were prevalent. Drivers consuming Tramadol (adjusted OR 11.41; 95% CI 1.27, 102.15) were at a significantly increased risk of motor vehicle collision. Older adult drivers who have a prescription for this medication may need to be aware of the potential risk. Further research is necessary in a larger, more nationally representative population.

Controlling charge transport mechanisms in molecular junctions: Distilling thermally induced hopping from coherent-resonant conduction.

PubMed

Kim, Hyehwang; Segal, Dvira

2017-04-28

The electrical conductance of molecular junctions may depend strongly on the temperature and weakly on molecular length, under two distinct mechanisms: phase-coherent resonant conduction, with charges proceeding via delocalized molecular orbitals, and incoherent thermally assisted multi-step hopping. While in the case of coherent conduction, the temperature dependence arises from the broadening of the Fermi distribution in the metal electrodes, in the latter case it corresponds to electron-vibration interaction effects on the junction. With the objective to distill the thermally activated hopping component, thus exposing intrinsic electron-vibration interaction phenomena on the junction, we suggest the design of molecular junctions with "spacers," extended anchoring groups that act to filter out phase-coherent resonant electrons. Specifically, we study the electrical conductance of fixed-gap and variable-gap junctions that include a tunneling block, with spacers at the boundaries. Using numerical simulations and analytical considerations, we demonstrate that in our design, resonant conduction is suppressed. As a result, the electrical conductance is dominated by two (rather than three) mechanisms: superexchange (deep tunneling) and multi-step thermally induced hopping. We further exemplify our analysis on DNA junctions with an A:T block serving as a tunneling barrier. Here, we show that the electrical conductance is insensitive to the number of G:C base-pairs at the boundaries. This indicates that the tunneling-to-hopping crossover revealed in such sequences truly corresponds to the properties of the A:T barrier.

Ambient Ozone Concentrations and the Risk of Perforated and Nonperforated Appendicitis: A Multicity Case-Crossover Study

PubMed Central

Tanyingoh, Divine; Dixon, Elijah; Johnson, Markey; Wheeler, Amanda J.; Myers, Robert P.; Bertazzon, Stefania; Saini, Vineet; Madsen, Karen; Ghosh, Subrata; Villeneuve, Paul J.

2013-01-01

Background: Environmental determinants of appendicitis are poorly understood. Past work suggests that air pollution may increase the risk of appendicitis. Objectives: We investigated whether ambient ground-level ozone (O3) concentrations were associated with appendicitis and whether these associations varied between perforated and nonperforated appendicitis. Methods: We based this time-stratified case-crossover study on 35,811 patients hospitalized with appendicitis from 2004 to 2008 in 12 Canadian cities. Data from a national network of fixed-site monitors were used to calculate daily maximum O3 concentrations for each city. Conditional logistic regression was used to estimate city-specific odds ratios (ORs) relative to an interquartile range (IQR) increase in O3 adjusted for temperature and relative humidity. A random-effects meta-analysis was used to derive a pooled risk estimate. Stratified analyses were used to estimate associations separately for perforated and nonperforated appendicitis. Results: Overall, a 16-ppb increase in the 7-day cumulative average daily maximum O3 concentration was associated with all appendicitis cases across the 12 cities (pooled OR = 1.07; 95% CI: 1.02, 1.13). The association was stronger among patients presenting with perforated appendicitis for the 7-day average (pooled OR = 1.22; 95% CI: 1.09, 1.36) when compared with the corresponding estimate for nonperforated appendicitis [7-day average (pooled OR = 1.02, 95% CI: 0.95, 1.09)]. Heterogeneity was not statistically significant across cities for either perforated or nonperforated appendicitis (p > 0.20). Conclusions: Higher levels of ambient O3 exposure may increase the risk of perforated appendicitis. PMID:23842601

An in silico approach helped to identify the best experimental design, population, and outcome for future randomized clinical trials.

PubMed

Bajard, Agathe; Chabaud, Sylvie; Cornu, Catherine; Castellan, Anne-Charlotte; Malik, Salma; Kurbatova, Polina; Volpert, Vitaly; Eymard, Nathalie; Kassai, Behrouz; Nony, Patrice

2016-01-01

The main objective of our work was to compare different randomized clinical trial (RCT) experimental designs in terms of power, accuracy of the estimation of treatment effect, and number of patients receiving active treatment using in silico simulations. A virtual population of patients was simulated and randomized in potential clinical trials. Treatment effect was modeled using a dose-effect relation for quantitative or qualitative outcomes. Different experimental designs were considered, and performances between designs were compared. One thousand clinical trials were simulated for each design based on an example of modeled disease. According to simulation results, the number of patients needed to reach 80% power was 50 for crossover, 60 for parallel or randomized withdrawal, 65 for drop the loser (DL), and 70 for early escape or play the winner (PW). For a given sample size, each design had its own advantage: low duration (parallel, early escape), high statistical power and precision (crossover), and higher number of patients receiving the active treatment (PW and DL). Our approach can help to identify the best experimental design, population, and outcome for future RCTs. This may be particularly useful for drug development in rare diseases, theragnostic approaches, or personalized medicine. Copyright © 2016 Elsevier Inc. All rights reserved.

Prevention of EP Migratory Contamination in a Cluster Randomized Trial to Increase tPA Use in Stroke (The INSTINCT Trial)

PubMed Central

Weston, Victoria C.; Meurer, William J.; Frederiksen, Shirley M.; Fox, Allison K.; Scott, Phillip A.

2016-01-01

Objectives Cluster randomized trials (CRTs) are increasingly utilized to evaluate quality improvement interventions aimed at healthcare providers. In trials testing emergency department interventions, migration of emergency physicians (EPs) between hospitals is an important concern, as contamination may affect both internal and external validity. We hypothesized that geographically isolating emergency departments would prevent migratory contamination in a CRT designed to increase ED delivery of tPA in stroke (The INSTINCT Trial). Methods INSTINCT was a prospective, cluster randomized, controlled trial. 24 Michigan community hospitals were randomly selected in matched pairs for study. Contamination was defined at the cluster level, with substantial contamination defined a priori as >10% of EPs affected. Non-adherence, total crossover (contamination + non-adherence), migration distance and characteristics were determined. Results 307 emergency physicians were identified at all sites. Overall, 7 (2.3%) changed study sites. 1 moved between control sites, leaving 6 (2.0%) total crossovers. Of these, 2 (0.7%) moved from intervention to control (contamination) and 4 (1.3%) moved from control to intervention (non-adherence). Contamination was observed in 2 of 12 control sites, with 17% and 9% contamination of the total site EP workforce at follow-up, respectively. Average migration distance was 42 miles for all EPs moving in the study and 35 miles for EPs moving from intervention to control sites. Conclusion The mobile nature of emergency physicians should be considered in the design of quality improvement CRTs. Increased reporting of contamination in CRTs is encouraged to clarify thresholds and facilitate CRT design. PMID:25440230

Quantum synchronization of a driven self-sustained oscillator.

PubMed

Walter, Stefan; Nunnenkamp, Andreas; Bruder, Christoph

2014-03-07

Synchronization is a universal phenomenon that is important both in fundamental studies and in technical applications. Here we investigate synchronization in the simplest quantum-mechanical scenario possible, i.e., a quantum-mechanical self-sustained oscillator coupled to an external harmonic drive. Using the power spectrum we analyze synchronization in terms of frequency entrainment and frequency locking in close analogy to the classical case. We show that there is a steplike crossover to a synchronized state as a function of the driving strength. In contrast to the classical case, there is a finite threshold value in driving. Quantum noise reduces the synchronized region and leads to a deviation from strict frequency locking.

The effect of nabilone on neuropsychological functions related to driving ability: an extended case series.

PubMed

Kurzthaler, Ilsemarie; Bodner, Thomas; Kemmler, Georg; Entner, Tanja; Wissel, Joerg; Berger, Thomas; Fleischhacker, W Wolfgang

2005-06-01

The primary goal of this prospective extended case series was to obtain the first data about the potential influence of nabilone intake on driving ability related neuropsychological functions. Six patients were investigated within a placebo controlled, double-blind crossover study of this synthetic cannabinoid (2 mg/day) in patients with multiple sclerosis and spasticity associated pain. Five neuropsychological functions (reaction time, working memory, divided attention, psychomotor speed and mental flexibility) were assessed. No indication was found of a deterioration of any of the five investigated neuropsychological functions during the 4-week treatment period with nabilone. Copyright 2005 John Wiley & Sons, Ltd.

Comparative study of the oral absorption of microencapsulated ferric saccharate and ferrous sulfate in humans.

PubMed

Contreras, Carlos; Barnuevo, María Dolores; Guillén, Isabel; Luque, Antonio; Lázaro, Elisabet; Espadaler, Jordi; López-Román, Javier; Villegas, José A

2014-01-01

Our objective was to compare the absorption of microencapsulated ferric saccharate (MFS) and ferrous sulfate (FS) in a fortified milk product, using a crossover design. Seventeen non-iron-deficient healthy adults from both sexes participated in the study. On each intervention day (days 1 and 8), after an overnight fast, the volunteers consumed one type of product (test or control) and blood sampling was carried out at different times. The interventions days were separated by 7-day washout periods. This study was double blinded, crossover and randomized for nature of the test meals. The primary outcomes of the study were total serum iron and transferrin saturation. No significant differences could be observed in serum iron concentration during the 6-h postprandial study due to the type of milk product consumed, and there was neither an effect of time nor an interaction between the type of milk product and time. Transferrin saturation significantly increased after the intake of both products (P < 0.005), reaching a peak value between hours 2 and 4. No significant differences were detected between MFS and FS, indicating that iron absorption from MFS is equivalent to absorption from FS. MFS is a new ingredient that allows the fortification of a wide range of food products, including heat-processed and non-acidic products with similar absorption to FS, designed to produce neither organoleptic changes nor off-color development during storage of fortified food.

Screening approach for identifying candidate drugs and drug-drug interactions related to hip fracture risk in persons with Alzheimer disease.

PubMed

Tolppanen, Anna-Maija; Taipale, Heidi; Koponen, Marjaana; Tanskanen, Antti; Lavikainen, Piia; Paananen, Jussi; Tiihonen, Jari; Hartikainen, Sirpa

2017-08-01

To assess whether a "drugome-wide" screen with case-crossover design is a feasible approach for identifying candidate drugs and drug-drug interactions. All community-dwelling residents of Finland who received a clinically verified Alzheimer disease diagnosis in 2005 to 2011 and experienced incident hip fracture (HF) afterwards (N = 4851). Three scenarios were used to test the sensitivity of this approach (1) hazard period 0 to 30 and control period 31 to 61 days before HF, (2) hazard period 0 to 30 and control period 336 to 366 days before HF, and (3) hazard period 0 to 14 and control period 16 to 30 days before HF. Nine, 44, and 5 drugs were associated with increased HF risk and 8, 23, and 4 with decreased risk in scenarios 1, 2, and 3, respectively. Six drugs were identified with scenario 1 only and 54 and 1 with scenarios 2 and 3, respectively. Only six drugs (metoprolol, simvastatin, trimethoprim, codeine combinations, fentanyl, and paracetamol) were associated with HF in all scenarios, four with 1 and 2 (cefalexin, buprenorphine, olanzapine, and memantine), and one with 1 and 3 (enalapril) or 2 and 3 (ciprofloxacin). The direction of associations was the same in all/both scenarios. The interaction results were equally versatile, with hydroxocobalamin*oxazepam being the only interaction observed in all scenarios. Case-crossover analysis is a potential approach for identifying candidate drugs and drug-drug interactions associated with adverse events as it implicitly controls for fixed confounders. The results are highly dependent on applied hazard and control periods, but the choice of periods can help in targeting the analyses to different phases of drug use. Copyright © 2017 John Wiley & Sons, Ltd.

A Randomized, Placebo-Controlled, Crossover Trial of Cannabis Cigarettes in Neuropathic Pain

PubMed Central

Wilsey, Barth; Marcotte, Thomas; Tsodikov, Alexander; Millman, Jeanna; Bentley, Heather; Gouaux, Ben; Fishman, Scott

2016-01-01

The Food and Drug Administration (FDA), Substance Abuse and Mental Health Services Administration (SAMHSA), and the National Institute for Drug Abuse (NIDA) report that no sound scientific studies support the medicinal use of cannabis. Despite this lack of scientific validation, many patients routinely use “medical marijuana,” and in many cases this use is for pain related to nerve injury. We conducted a double-blinded, placebo-controlled, crossover study evaluating the analgesic efficacy of smoking cannabis for neuropathic pain. Thirty-eight patients with central and peripheral neuropathic pain underwent a standardized procedure for smoking either high-dose (7%), low-dose (3.5%), or placebo cannabis. In addition to the primary outcome of pain intensity, secondary outcome measures included evoked pain using heat-pain threshold, sensitivity to light touch, psychoactive side effects, and neuropsychological performance. A mixed linear model demonstrated an analgesic response to smoking cannabis. No effect on evoked pain was seen. Psychoactive effects were minimal and well-tolerated, with some acute cognitive effects, particularly with memory, at higher doses. PMID:18403272

Analysis of crossover between local and massive separation on airfoils

NASA Technical Reports Server (NTRS)

Barnett, Mark

1987-01-01

The occurrence of massive separation on airfoils operating at high Reynolds number poses an important problem to the aerodynamicist. In the present study, the phenomenon of crossover, induced by airfoil thickness, between local separation and massive separation is investigated for low speed (incompressible), symmetric flow past realistic airfoil geometries. This problem is studied both for the infinite Reynolds number asymptotic limit using triple-deck theory and for finite Reynolds number using interacting boundary-layer theory. Numerical results are presented which illustrate how the flow evolves from local to massive separation as the airfoil thickness is increased. The results of the triple-deck and the interacting boundary-layer analyses are found to be in qualitative agreement for the NACA four digit series and an uncambered supercritical airfoil. The effect of turbulence on the evolution of the flow is also considered. Solutions are presented for turbulent flows past a NACA 0014 airfoil and a circular cylinder. For the latter case, the calculated surface pressure distribution is found to agree well with experimental data if the proper eddy pressure level is specified.

Environmental triggers of COPD symptoms: a case cross-over study.

PubMed

Sama, Susan R; Kriebel, David; Gore, Rebecca J; DeVries, Rebecca; Rosiello, Richard

2017-01-01

This study investigated the hypothesis that common environmental chemical exposures with known irritant or sensitising properties trigger exacerbations for patients with chronic obstructive pulmonary disease (COPD). We conducted a case cross-over study in 168 patients with COPD who were members of a disease management group in central Massachusetts. Participants completed a baseline health survey and several short exposure surveys. Exposure surveys were administered by a nurse when a participant telephoned to report an exacerbation (case periods) and at a maximum of three randomly identified control periods when they were not experiencing an exacerbation. We compared exposures in the week preceding an exacerbation with exposures in normal (non-exacerbation) weeks. The questionnaire assessed short-term (1 week) home, community and workplace activities and exposures that may be associated with COPD exacerbation. Self-reported exercise was negatively associated with exacerbation (OR=0.59, 95% CI: 0.35 to 1.00). Among the environmental chemical exposures, car and truck exhaust (OR=4.36, 95% CI: 1.76 to 10.80) and use of scented laundry products (OR=2.69, 95% CI: 1.31 to 5.52) showed strong positive effects. Self-reported respiratory infections were strongly associated with exacerbation (OR=7.90, 95% CI 4.29 to 14.50). Variations in outdoor temperature were associated with COPD exacerbation risk (moderate versus cold temperature OR=1.95, 95% CI 1.09 to 3.49 and warm versus cold OR=0.43, 95% CI: 0.26 to 0.70). These results suggest that some environmental chemical exposures may play a role in triggering COPD exacerbations. If confirmed, they may provide useful guidance for patients with COPD to better manage their disease.

Environmental triggers of COPD symptoms: a case cross-over study

PubMed Central

Sama, Susan R; Kriebel, David; Gore, Rebecca J; DeVries, Rebecca; Rosiello, Richard

2017-01-01

Introduction This study investigated the hypothesis that common environmental chemical exposures with known irritant or sensitising properties trigger exacerbations for patients with chronic obstructive pulmonary disease (COPD). Methods We conducted a case cross-over study in 168 patients with COPD who were members of a disease management group in central Massachusetts. Participants completed a baseline health survey and several short exposure surveys. Exposure surveys were administered by a nurse when a participant telephoned to report an exacerbation (case periods) and at a maximum of three randomly identified control periods when they were not experiencing an exacerbation. We compared exposures in the week preceding an exacerbation with exposures in normal (non-exacerbation) weeks. The questionnaire assessed short-term (1 week) home, community and workplace activities and exposures that may be associated with COPD exacerbation. Results Self-reported exercise was negatively associated with exacerbation (OR=0.59, 95% CI: 0.35 to 1.00). Among the environmental chemical exposures, car and truck exhaust (OR=4.36, 95% CI: 1.76 to 10.80) and use of scented laundry products (OR=2.69, 95% CI: 1.31 to 5.52) showed strong positive effects. Self-reported respiratory infections were strongly associated with exacerbation (OR=7.90, 95% CI 4.29 to 14.50). Variations in outdoor temperature were associated with COPD exacerbation risk (moderate versus cold temperature OR=1.95, 95% CI 1.09 to 3.49 and warm versus cold OR=0.43, 95% CI: 0.26 to 0.70). Conclusions These results suggest that some environmental chemical exposures may play a role in triggering COPD exacerbations. If confirmed, they may provide useful guidance for patients with COPD to better manage their disease. PMID:29071071

Traffic-related air pollution and the onset of myocardial infarction: disclosing benzene as a trigger? A small-area case-crossover study.

PubMed

Bard, Denis; Kihal, Wahida; Schillinger, Charles; Fermanian, Christophe; Ségala, Claire; Glorion, Sophie; Arveiler, Dominique; Weber, Christiane

2014-01-01

Exposure to traffic is an established risk factor for the triggering of myocardial infarction (MI). Particulate matter, mainly emitted by diesel vehicles, appears to be the most important stressor. However, the possible influence of benzene from gasoline-fueled cars has not been explored so far. We conducted a case-crossover study from 2,134 MI cases recorded by the local Coronary Heart Disease Registry (2000-2007) in the Strasbourg Metropolitan Area (France). Available individual data were age, gender, previous history of ischemic heart disease and address of residence at the time of the event. Nitrogen dioxide, particles of median aerodynamic diameter <10 µm (PM10), ozone, carbon monoxide and benzene air concentrations were modeled on an hourly basis at the census block level over the study period using the deterministic ADMS-Urban air dispersion model. Model input data were emissions inventories, background pollution measurements, and meteorological data. We have found a positive, statistically significant association between concentrations of benzene and the onset of MI: per cent increase in risk for a 1 µg/m3 increase in benzene concentration in the previous 0, 0-1 and 1 day was 10.4 (95% confidence interval 3-18.2), 10.7 (2.7-19.2) and 7.2 (0.3-14.5), respectively. The associations between the other pollutants and outcome were much lower and in accordance with the literature. We have observed that benzene in ambient air is strongly associated with the triggering of MI. This novel finding needs confirmation. If so, this would mean that not only diesel vehicles, the main particulate matter emitters, but also gasoline-fueled cars--main benzene emitters-, should be taken into account for public health action.

Assessment of long-range correlation in animal behavior time series: The temporal pattern of locomotor activity of Japanese quail (Coturnix coturnix) and mosquito larva (Culex quinquefasciatus)

NASA Astrophysics Data System (ADS)

Kembro, Jackelyn M.; Flesia, Ana Georgina; Gleiser, Raquel M.; Perillo, María A.; Marin, Raul H.

2013-12-01

Detrended Fluctuation Analysis (DFA) is a method that has been frequently used to determine the presence of long-range correlations in human and animal behaviors. However, according to previous authors using statistical model systems, in order to correctly use DFA different aspects should be taken into account such as: (1) the establishment by hypothesis testing of the absence of short term correlation, (2) an accurate estimation of a straight line in the log-log plot of the fluctuation function, (3) the elimination of artificial crossovers in the fluctuation function, and (4) the length of the time series. Taking into consideration these factors, herein we evaluated the presence of long-range correlation in the temporal pattern of locomotor activity of Japanese quail (Coturnix coturnix) and mosquito larva (Culex quinquefasciatus). In our study, modeling the data with the general autoregressive integrated moving average (ARFIMA) model, we rejected the hypothesis of short-range correlations (d=0) in all cases. We also observed that DFA was able to distinguish between the artificial crossover observed in the temporal pattern of locomotion of Japanese quail and the crossovers in the correlation behavior observed in mosquito larvae locomotion. Although the test duration can slightly influence the parameter estimation, no qualitative differences were observed between different test durations.

Impact of membrane characteristics on the performance and cycling of the Br-2-H-2 redox flow cell

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tucker, MC; Cho, KT; Spingler, FB

2015-06-15

The Br-2/H-2 redox flow cell shows promise as a high-power, low-cost energy storage device. In this paper, the effect of various aspects of material selection and processing of proton exchange membranes on the operation of the Br-2/H-2 redox flow cell is determined. Membrane properties have a significant impact on the performance and efficiency of the system. In particular, there is a tradeoff between conductivity and crossover, where conductivity limits system efficiency at high current density and crossover limits efficiency at low current density. The impact of thickness, pretreatment procedure, swelling state during cell assembly, equivalent weight, membrane reinforcement, and additionmore » of a microporous separator layer on this tradeoff is assessed. NR212 (50 mu m) pretreated by soaking in 70 degrees C water is found to be optimal for the studied operating conditions. For this case, an energy efficiency of greater than 75% is achieved for current density up to 400 mA cm(-2), with a maximum obtainable energy efficiency of 88%. A cell with this membrane was cycled continuously for 3164 h. Membrane transport properties, including conductivity and bromine and water crossover, were found to decrease moderately upon cycling but remained higher than those for the as-received membrane. (C) 2015 Elsevier B.V. All rights reserved.« less

Herb-drug interaction: a case study of effect of ginger on the pharmacokinetic of metronidazole in rabbit.

PubMed

Okonta, J M; Uboh, M; Obonga, W O

2008-01-01

The effect of ginger on the pharmacokinectic of metronidazole was studied using rabbits in a crossover study method. The relevance of this study borders on the wide use of ginger for culinary and phytotherapeutic purposes, and metronidazole that is commonly used for every gastrointestinal complain in our communities without prescription. Ginger significantly increased the absorption and plasma half-life, and significantly decreased the elimination rate constant and clearance of metronidazole (P<0.05). Thus, in clinical practice, the patients should be advised on the serious implication of using both items together.

Pretraining and posttraining assessment of residents' performance in the fourth accreditation council for graduate medical education competency: patient communication skills.

PubMed

Chandawarkar, Rajiv Y; Ruscher, Kimberly A; Krajewski, Aleksandra; Garg, Manish; Pfeiffer, Carol; Singh, Rekha; Longo, Walter E; Kozol, Robert A; Lesnikoski, Beth; Nadkarni, Prakash

2011-08-01

Structured communication curricula will improve surgical residents' ability to communicate effectively with patients. A prospective study approved by the institutional review board involved 44 University of Connecticut general surgery residents. Residents initially completed a written baseline survey to assess general communication skills awareness. In step 1 of the study, residents were randomized to 1 of 2 simulations using standardized patient instructors to mimic patients receiving a diagnosis of either breast or rectal cancer. The standardized patient instructors scored residents' communication skills using a case-specific content checklist and Master Interview Rating Scale. In step 2 of the study, residents attended a 3-part interactive program that comprised (1) principles of patient communication; (2) experiences of a surgeon (role as physician, patient, and patient's spouse); and (3) role-playing (3-resident groups played patient, physician, and observer roles and rated their own performance). In step 3, residents were retested as in step 1, using a crossover case design. Scores were analyzed using Wilcoxon signed rank test with a Bonferroni correction. Case-specific performance improved significantly, from a pretest content checklist median score of 8.5 (65%) to a posttest median of 11.0 (84%) (P = .005 by Wilcoxon signed rank test for paired ordinal data)(n = 44). Median Master Interview Rating Scale scores changed from 58.0 before testing (P = .10) to 61.5 after testing (P = .94). Difference between overall rectal cancer scores and breast cancer scores also were not significant. Patient communication skills need to be taught as part of residency training. With limited training, case-specific skills (herein, involving patients with cancer) are likely to improve more than general communication skills.

Flooding and Clostridium difficile infection: a case-crossover analysis

EPA Science Inventory

Clostridium difficile is a bacterium that can spread by water. It often causes acute gastrointestinal illness in older adults who are hospttalized and/or receiving antibiotics; however, community­ associated infections affecting otherwise healthy individuals have become more comm...

Evaluation of multiple comparison correction procedures in drug assessment studies using LORETA maps.

PubMed

Alonso, Joan Francesc; Romero, Sergio; Mañanas, Miguel Ángel; Rojas, Mónica; Riba, Jordi; Barbanoj, Manel José

2015-10-01

The identification of the brain regions involved in the neuropharmacological action is a potential procedure for drug development. These regions are commonly determined by the voxels showing significant statistical differences after comparing placebo-induced effects with drug-elicited effects. LORETA is an electroencephalography (EEG) source imaging technique frequently used to identify brain structures affected by the drug. The aim of the present study was to evaluate different methods for the correction of multiple comparisons in the LORETA maps. These methods which have been commonly used in neuroimaging and also simulated studies have been applied on a real case of pharmaco-EEG study where the effects of increasing benzodiazepine doses on the central nervous system measured by LORETA were investigated. Data consisted of EEG recordings obtained from nine volunteers who received single oral doses of alprazolam 0.25, 0.5, and 1 mg, and placebo in a randomized crossover double-blind design. The identification of active regions was highly dependent on the selected multiple test correction procedure. The combined criteria approach known as cluster mass was useful to reveal that increasing drug doses led to higher intensity and spread of the pharmacologically induced changes in intracerebral current density.

Are Emotions Transmitted From Work to Family? A Crossover Model of Psychological Contract Breach.

PubMed

Liang, Huai-Liang

2018-01-01

Based on affective events theory and the crossover model, this study examines the effect of psychological contract breach on employee dysfunctional behavior and partner family undermining and explores the crossover effect of employee dysfunctional behavior on partner family undermining in work-family issues. This study collected 370 employee-partner dyads (277 male employees, 93 female employees, M age = 43.59 years) from a large manufacturing organization. The results of this study support the conception that employees' psychological contract breach results in frustration in the workplace. In addition, mediation analysis results reveal that psychological contract breach relates to employee dysfunctional behavior in the workplace. The findings show that partners' psychological strain mediates the relationship between employee dysfunctional behavior and partner family undermining. Furthermore, these findings provide investigations for the crossover model to display the value of psychological contract breach in family issues.

Short-term effects of ozone air pollution on hospital admissions for myocardial infarction: A time-stratified case-crossover study in Taipei.

PubMed

Chiu, Hui-Fen; Weng, Yi-Hao; Chiu, Ya-Wen; Yang, Chun-Yuh

2017-01-01

This study was undertaken to determine whether there was a correlation between ambient ozone (O 3 ) levels and number of hospital admissions for myocardial infarction (MI) in Taipei, Taiwan. Hospital admissions for MI and ambient air pollution data for Taipei were obtained for the period from 2006 to 2010. The relative risk (RR) of hospital admissions for MI was estimated using a time-stratified case-crossover approach, controlling for weather variables, day of the week, seasonality, and long-term time trends. For the single-pollutant model (without adjustment for other pollutants), increased RR for a number of MI admissions was significantly associated with higher O 3 levels both on warm days (>23°C) and on cool days (<23°C). This observation was accompanied by an interquartile range elevation correlated with a 7% (95% CI = 2%-12%) and 17% (95% CI = 11%-25%) rise in number of MI admissions, respectively. In the two-pollutant models, no significant associations between ambient O 3 concentrations and number of MI admissions were observed on warm days. However, on cool days, correlation between ambient O 3 after inclusion of each of the other five pollutants, particulate matter (PM 10 or PM 2.5 ), sulfur dioxide (SO 2 ), nitrogen dioxide (NO 2 ) or carbon monoxide (CO), and number of MI admissions remained significant. This study provides evidence that higher levels of ambient O 3 increase the RR of number of hospital admissions for MI.

Chest Compression With Personal Protective Equipment During Cardiopulmonary Resuscitation: A Randomized Crossover Simulation Study.

PubMed

Chen, Jie; Lu, Kai-Zhi; Yi, Bin; Chen, Yan

2016-04-01

Following a chemical, biological, radiation, and nuclear incident, prompt cardiopulmonary resuscitation (CPR) procedure is essential for patients who suffer cardiac arrest. But CPR when wearing personal protection equipment (PPE) before decontamination becomes a challenge for healthcare workers (HCW). Although previous studies have assessed the impact of PPE on airway management, there is little research available regarding the quality of chest compression (CC) when wearing PPE.A present randomized cross-over simulation study was designed to evaluate the effect of PPE on CC performance using mannequins.The study was set in one university medical center in the China.Forty anesthesia residents participated in this randomized cross-over study.Each participant performed 2 min of CC on a manikin with and without PPE, respectively. Participants were randomized into 2 groups that either performed CC with PPE first, followed by a trial without PPE after a 180-min rest, or vice versa.CPR recording technology was used to objectively quantify the quality of CC. Additionally, participants' physiological parameters and subjective fatigue score values were recorded.With the use of PPE, a significant decrease of the percentage of effective compressions (41.3 ± 17.1% with PPE vs 67.5 ± 15.6% without PPE, P < 0.001) and the percentage of adequate compressions (67.7 ± 18.9% with PPE vs 80.7 ± 15.5% without PPE, P < 0.001) were observed. Furthermore, the increases in heart rate, mean arterial pressure, and subjective fatigue score values were more obvious with the use of PPE (all P < 0.01).We found significant deterioration of CC performance in HCW with the use of a level-C PPE, which may be a disadvantage for enhancing survival of cardiac arrest.

Noise performance of frequency modulation Kelvin force microscopy

PubMed Central

Deresmes, Dominique; Mélin, Thierry

2014-01-01

Summary Noise performance of a phase-locked loop (PLL) based frequency modulation Kelvin force microscope (FM-KFM) is assessed. Noise propagation is modeled step by step throughout the setup using both exact closed loop noise gains and an approximation known as “noise gain” from operational amplifier (OpAmp) design that offers the advantage of decoupling the noise performance study from considerations of stability and ideal loop response. The bandwidth can be chosen depending on how much noise is acceptable and it is shown that stability is not an issue up to a limit that will be discussed. With thermal and detector noise as the only sources, both approaches yield PLL frequency noise expressions equal to the theoretical value for self-oscillating circuits and in agreement with measurement, demonstrating that the PLL components neither modify nor contribute noise. Kelvin output noise is then investigated by modeling the surrounding bias feedback loop. A design rule is proposed that allows choosing the AC modulation frequency for optimized sharing of the PLL bandwidth between Kelvin and topography loops. A crossover criterion determines as a function of bandwidth, temperature and probe parameters whether thermal or detector noise is the dominating noise source. Probe merit factors for both cases are then established, suggesting how to tackle noise performance by probe design. Typical merit factors of common probe types are compared. This comprehensive study is an encouraging step toward a more integral performance assessment and a remedy against focusing on single aspects and optimizing around randomly chosen key values. PMID:24455457

A three-dimensional non-isothermal model for a membraneless direct methanol redox fuel cell

NASA Astrophysics Data System (ADS)

Wei, Lin; Yuan, Xianxia; Jiang, Fangming

2018-05-01

In the membraneless direct methanol redox fuel cell (DMRFC), three-dimensional electrodes contribute to the reduction of methanol crossover and the open separator design lowers the system cost and extends its service life. In order to better understand the mechanisms of this configuration and further optimize its performance, the development of a three-dimensional numerical model is reported in this work. The governing equations of the multi-physics field are solved based on computational fluid dynamics methodology, and the influence of the CO2 gas is taken into consideration through the effective diffusivities. The numerical results are in good agreement with experimental data, and the deviation observed for cases of large current density may be related to the single-phase assumption made. The three-dimensional electrode is found to be effective in controlling methanol crossover in its multi-layer structure, while it also increases the flow resistance for the discharging products. It is found that the current density distribution is affected by both the electronic conductivity and the concentration of reactants, and the temperature rise can be primarily attributed to the current density distribution. The sensitivity and reliability of the model are analyzed through the investigation of the effects of cell parameters, including porosity values of gas diffusion layers and catalyst layers, methanol concentration and CO2 volume fraction, on the polarization characteristics.

Individual hemoglobin mass response to normobaric and hypobaric "live high-train low": A one-year crossover study.

PubMed

Hauser, Anna; Troesch, Severin; Saugy, Jonas J; Schmitt, Laurent; Cejuela-Anta, Roberto; Faiss, Raphael; Steiner, Thomas; Robinson, Neil; Millet, Grégoire P; Wehrlin, Jon P

2017-08-01

The purpose of this research was to compare individual hemoglobin mass (Hb mass ) changes following a live high-train low (LHTL) altitude training camp under either normobaric hypoxia (NH) or hypobaric hypoxia (HH) conditions in endurance athletes. In a crossover design with a one-year washout, 15 male triathletes randomly performed two 18-day LHTL training camps in either HH or NH. All athletes slept at 2,250 meters and trained at altitudes <1,200 meters. Hb mass was measured in duplicate with the optimized carbon monoxide rebreathing method before (pre) and immediately after (post) each 18-day training camp. Hb mass increased similarly in HH (916-957 g, 4.5 ± 2.2%, P < 0.001) and in NH (918-953 g, 3.8 ± 2.6%, P < 0.001). Hb mass changes did not differ between HH and NH ( P = 0.42). There was substantial interindividual variability among subjects to both interventions (i.e., individual responsiveness or the individual variation in the response to an intervention free of technical noise): 0.9% in HH and 1.7% in NH. However, a correlation between intraindividual ΔHb mass changes (%) in HH and in NH ( r = 0.52, P = 0.048) was observed. HH and NH evoked similar mean Hb mass increases following LHTL. Among the mean Hb mass changes, there was a notable variation in individual Hb mass response that tended to be reproducible. NEW & NOTEWORTHY This is the first study to compare individual hemoglobin mass (Hb mass ) response to normobaric and hypobaric live high-train low using a same-subject crossover design. The main findings indicate that hypobaric and normobaric hypoxia evoked a similar mean increase in Hb mass following 18 days of live high-train low. Notable variability and reproducibility in individual Hb mass responses between athletes was observed, indicating the importance of evaluating individual Hb mass response to altitude training. Copyright © 2017 the American Physiological Society.

The Effect of Three or Six Years of Denosumab Exposure in Women With Postmenopausal Osteoporosis: Results From the FREEDOM Extension

PubMed Central

Chapurlat, Roland; Brandi, Maria-Luisa; Brown, Jacques P.; Czerwiński, Edward; Krieg, Marc-Antoine; Mellström, Dan; Radominski, Sebastião C.; Reginster, Jean-Yves; Resch, Heinrich; Ivorra, Jose A. Román; Roux, Christian; Vittinghoff, Eric; Daizadeh, Nadia S.; Wang, Andrea; Bradley, Michelle N.; Franchimont, Nathalie; Geller, Michelle L.; Wagman, Rachel B.; Cummings, Steven R.; Papapoulos, Socrates

2013-01-01

Context: The Fracture Reduction Evaluation of Denosumab in Osteoporosis Every 6 Months (FREEDOM) extension is evaluating the long-term efficacy and safety of denosumab for up to 10 years. Objective: The objective of the study was to report results from the first 3 years of the extension, representing up to 6 years of denosumab exposure. Design, Setting, and Participants: This was a multicenter, international, open-label study of 4550 women. Intervention: Women from the FREEDOM denosumab group received 3 more years of denosumab for a total of 6 years (long-term) and women from the FREEDOM placebo group received 3 years of denosumab (crossover). Main Outcome Measures: Bone turnover markers (BTMs), bone mineral density (BMD), fracture, and safety data are reported. Results: Reductions in BTMs were maintained (long-term) or achieved rapidly (crossover) after denosumab administration. In the long-term group, BMD further increased for cumulative 6-year gains of 15.2% (lumbar spine) and 7.5% (total hip). During the first 3 years of denosumab treatment, the crossover group had significant gains in lumbar spine (9.4%) and total hip (4.8%) BMD, similar to the long-term group during the 3-year FREEDOM trial. In the long-term group, fracture incidences remained low and below the rates projected for a virtual placebo cohort. In the crossover group, 3-year incidences of new vertebral and nonvertebral fractures were similar to those of the FREEDOM denosumab group. Incidence rates of adverse events did not increase over time. Six participants had events of osteonecrosis of the jaw confirmed by adjudication. One participant had a fracture adjudicated as consistent with atypical femoral fracture. Conclusion: Denosumab treatment for 6 years remained well tolerated, maintained reduced bone turnover, and continued to increase BMD. Fracture incidence remained low. PMID:23979955

Diffusion in an expanding medium: Fokker-Planck equation, Green's function, and first-passage properties

NASA Astrophysics Data System (ADS)

Yuste, S. B.; Abad, E.; Escudero, C.

2016-09-01

We present a classical, mesoscopic derivation of the Fokker-Planck equation for diffusion in an expanding medium. To this end, we take a conveniently generalized Chapman-Kolmogorov equation as the starting point. We obtain an analytical expression for the Green's function (propagator) and investigate both analytically and numerically how this function and the associated moments behave. We also study first-passage properties in expanding hyperspherical geometries. We show that in all cases the behavior is determined to a great extent by the so-called Brownian conformal time τ (t ) , which we define via the relation τ ˙=1 /a2 , where a (t ) is the expansion scale factor. If the medium expansion is driven by a power law [a (t ) ∝tγ with γ >0 ] , then we find interesting crossover effects in the mixing effectiveness of the diffusion process when the characteristic exponent γ is varied. Crossover effects are also found at the level of the survival probability and of the moments of the first passage-time distribution with two different regimes separated by the critical value γ =1 /2 . The case of an exponential scale factor is analyzed separately both for expanding and contracting media. In the latter situation, a stationary probability distribution arises in the long-time limit.

Tolerance of beta blocked hypertensives during orthostatic and altitude stress.

DOT National Transportation Integrated Search

1992-04-01

To evaluate the effects of orthostatic, altitude, and pharmacologic stresses upon civil aviation-specific performance, a double-blind, randomized, crossover trial of atenolol, 100mg, was designed and executed. Hypertensive males are females qualifyin...

Logical NAND and NOR Operations Using Algorithmic Self-assembly of DNA Molecules

NASA Astrophysics Data System (ADS)

Wang, Yanfeng; Cui, Guangzhao; Zhang, Xuncai; Zheng, Yan

DNA self-assembly is the most advanced and versatile system that has been experimentally demonstrated for programmable construction of patterned systems on the molecular scale. It has been demonstrated that the simple binary arithmetic and logical operations can be computed by the process of self assembly of DNA tiles. Here we report a one-dimensional algorithmic self-assembly of DNA triple-crossover molecules that can be used to execute five steps of a logical NAND and NOR operations on a string of binary bits. To achieve this, abstract tiles were translated into DNA tiles based on triple-crossover motifs. Serving as input for the computation, long single stranded DNA molecules were used to nucleate growth of tiles into algorithmic crystals. Our method shows that engineered DNA self-assembly can be treated as a bottom-up design techniques, and can be capable of designing DNA computer organization and architecture.

Serendipity and strategy in rapid innovation.

PubMed

Fink, T M A; Reeves, M; Palma, R; Farr, R S

2017-12-08

Innovation is to organizations what evolution is to organisms: it is how organizations adapt to environmental change and improve. Yet despite advances in our understanding of evolution, what drives innovation remains elusive. On the one hand, organizations invest heavily in systematic strategies to accelerate innovation. On the other, historical analysis and individual experience suggest that serendipity plays a significant role. To unify these perspectives, we analysed the mathematics of innovation as a search for designs across a universe of component building blocks. We tested our insights using data from language, gastronomy and technology. By measuring the number of makeable designs as we acquire components, we observed that the relative usefulness of different components can cross over time. When these crossovers are unanticipated, they appear to be the result of serendipity. But when we can predict crossovers in advance, they offer opportunities to strategically increase the growth of the product space.

Separable Roles for a Caenorhabditis elegans RMI1 Homolog in Promoting and Antagonizing Meiotic Crossovers Ensure Faithful Chromosome Inheritance

PubMed Central

Jagut, Marlène; Hamminger, Patricia; Woglar, Alexander; Millonigg, Sophia; Paulin, Luis; Mikl, Martin; Dello Stritto, Maria Rosaria; Tang, Lois; Habacher, Cornelia; Tam, Angela; Gallach, Miguel; von Haeseler, Arndt; Villeneuve, Anne M.; Jantsch, Verena

2016-01-01

During the first meiotic division, crossovers (COs) between homologous chromosomes ensure their correct segregation. COs are produced by homologous recombination (HR)-mediated repair of programmed DNA double strand breaks (DSBs). As more DSBs are induced than COs, mechanisms are required to establish a regulated number of COs and to repair remaining intermediates as non-crossovers (NCOs). We show that the Caenorhabditis elegans RMI1 homolog-1 (RMH-1) functions during meiosis to promote both CO and NCO HR at appropriate chromosomal sites. RMH-1 accumulates at CO sites, dependent on known pro-CO factors, and acts to promote CO designation and enforce the CO outcome of HR-intermediate resolution. RMH-1 also localizes at NCO sites and functions in parallel with SMC-5 to antagonize excess HR-based connections between chromosomes. Moreover, RMH-1 also has a major role in channeling DSBs into an NCO HR outcome near the centers of chromosomes, thereby ensuring that COs form predominantly at off-center positions. PMID:27011106

Cross-over endovascular retrieval of a lost guide wire from the subclavian vein.

PubMed

Struck, M F; Kaden, I; Heiser, A; Steen, M

2008-01-01

The lost guidewire in central venous catheterization is a commonly described complication. The percutaneous endovascular retrieval method is safe and has a very low complication rate. Guidewires extending to the inferior cava vein are usually retrieved via the femoral vein. Under special circumstances, femoral venous access may be impossible and alternative vascular approaches are required. We report a case in which we used an alternative vascular approach, from the subclavian site contralateral to the insertion, in a patient with extensive inguinal burn injuries. Cross-over subclavian retrieval can be an alternative approach for retrieval of a lost guidewire, but it involves an increased risk of puncture-related complications such as pneumothorax.

Dynamical instability of a driven-dissipative electron-hole condensate in the BCS-BEC crossover region

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hanai, Ryo; Littlewood, Peter B.; Ohashi, Yoji

2017-09-01

We present a stability analysis on a driven-dissipative electron-hole condensate in the BCS (Bardeen-Cooper-Schrieffer)-BEC (Bose-Einstein-condensation)-crossover region. Extending the combined BCS-Leggett theory with the generalized random phase approximation (GRPA) to the non-equilibrium case by employing the Keldysh formalism, we show that the pumping-and-decay of carriers causes a depairing effect on excitons. This phenomenon gives rise to an attractive interaction between excitons in the BEC regime, as well as a supercurrent that anomalously flows anti-parallel to ∇θ(r) (where θ(r) is the phase of the condensate) in the BCS regime, both leading to dynamical instabilities of an exciton-BEC.

Performance factors of mobile rich media job aids for community health workers.

PubMed

Florez-Arango, Jose F; Iyengar, M Sriram; Dunn, Kim; Zhang, Jiajie

2011-01-01

To study and analyze the possible benefits on performance of community health workers using point-of-care clinical guidelines implemented as interactive rich media job aids on small-format mobile platforms. A crossover study with one intervention (rich media job aids) and one control (traditional job aids), two periods, with 50 community health workers, each subject solving a total 15 standardized cases per period per period (30 cases in total per subject). Error rate per case and task, protocol compliance. A total of 1394 cases were evaluated. Intervention reduces errors by an average of 33.15% (p = 0.001) and increases protocol compliance 30.18% (p < 0.001). Limitations Medical cases were presented on human patient simulators in a laboratory setting, not on real patients. These results indicate encouraging prospects for mHealth technologies in general, and the use of rich media clinical guidelines on cell phones in particular, for the improvement of community health worker performance in developing countries.

Bloodcurdling movies and measures of coagulation: Fear Factor crossover trial

PubMed Central

Nemeth, Banne; Scheres, Luuk J J; Lijfering, Willem M

2015-01-01

Objective To assess whether, as has been hypothesised since medieval times, acute fear can curdle blood. Design Crossover trial. Setting Main meeting room of Leiden University’s Department of Clinical Epidemiology, the Netherlands, converted to a makeshift cinema. Participants 24 healthy volunteers aged ≤30 years recruited among students, alumni, and employees of the Leiden University Medical Center: 14 were assigned to watch a frightening (horror) movie followed by a non-threatening (educational) movie and 10 to watch the movies in reverse order. The movies were viewed more than a week apart at the same time of day and both lasted approximately 90 minutes. Main outcome measures The primary outcome measures were markers, or “fear factors” of coagulation activity: blood coagulant factor VIII, D-dimer, thrombin-antithrombin complexes, and prothrombin fragments 1+2. The secondary outcome was participant reported fear experienced during each movie using a visual analogue fear scale. Results All participants completed the study. The horror movie was perceived to be more frightening than the educational movie on a visual analogue fear scale (mean difference 5.4, 95% confidence interval 4.7 to 6.1). The difference in factor VIII levels before and after watching the movies was higher for the horror movie than for the educational movie (mean difference of differences 11.1 IU/dL (111 IU/L), 95% confidence interval 1.2 to 21.0 IU/dL). The effect of either movie on levels of thrombin-antithrombin complexes, D-dimer, and prothrombin fragments 1+2 did not differ. Conclusion Frightening (in this case, horror) movies are associated with an increase of blood coagulant factor VIII without actual thrombin formation in young and healthy adults. Trial registration ClinicalTrials.gov NCT02601053. PMID:26673787

Investigations of botanicals on food intake, satiety, weight loss, and oxidative stress: a study protocol of a double-blind, placebo-controlled, crossover study

PubMed Central

Anton, Stephen D.; Shuster, Jonathan; Leeuwenburgh, Christiaan

2013-01-01

Background Botanicals represent an important and underexplored source of potential new therapies that may facilitate caloric restriction and thereby produce long-term weight loss. In particular, one promising botanical that may reduce food intake and body weight by affecting neuroendocrine pathways related to satiety is Garcinia cambogia (Garcinia cambogia Desr.)-derived (−)-hydroxycitric acid (HCA). Methods and Design The objective of this article is to describe the protocol of a clinical trial designed to directly test the effect that Garcinia cambogia-derived HCA has on food intake, satiety, weight loss, and oxidative stress levels, and to serve as a model for similar trials. A total of 48 healthy, overweight and obese individuals (body mass index; BMI range = 25.0 – 39.9) between the ages of 50 to 70 will participate in this double-blind, placebo-controlled, crossover study designed to examine the effects of two doses of Garcinia cambogia-derived HCA on food intake, satiety, weight loss, and oxidative stress levels. This trial will take place at the University of Florida (UF)’s Aging and Rehabilitation Research Center (ARRC) and UF Clinical Research Center (CRC). Food intake represents the primary outcome measure and is calculated based on the total calories consumed at breakfast, lunch, and dinner meals during each test meal day at the CRC. This study can be completed with far fewer subjects than a parallel design. Discussion Of the numerous botanical compounds, the compound Garcinia cambogia-derived HCA was selected for testing in the present study because of its potential to safely reduce food intake, body weight, and oxidative stress levels. We will review potential mechanisms of action and safety parameters throughout this clinical trial, which is registered at ClinicalTrials.gov under NCT01238887. Trial registration ClinicalTrials.gov (Identifier: NCT01238887). PMID:22088584

A prospective randomised cross-over study of the effect of insulin analogues and human insulin on the frequency of severe hypoglycaemia in patients with type 1 diabetes and recurrent hypoglycaemia (the HypoAna trial): study rationale and design

PubMed Central

2012-01-01

Background Severe hypoglycaemia still represents a significant problem in insulin-treated diabetes. Most patients do not experience severe hypoglycaemia often. However, 20% of patients with type 1 diabetes experience recurrent severe hypoglycaemia corresponding to at least two episodes per year. The effect of insulin analogues on glycaemic control has been documented in large trials, while their effect on the frequency of severe hypoglycaemia is less clear, especially in patients with recurrent severe hypoglycaemia. The HypoAna Trial is designed to investigate whether short-acting and long-acting insulin analogues in comparison with human insulin are superior in reducing the occurrence of severe hypoglycaemic episodes in patients with recurrent hypoglycaemia. This paper reports the study design of the HypoAna Trial. Methods/design The study is a Danish two-year investigator-initiated, prospective, randomised, open, blinded endpoint (PROBE), multicentre, cross-over trial investigating the effect of insulin analogues versus human insulin on the frequency of severe hypoglycaemia in subjects with type 1 diabetes. Patients are randomised to treatment with basal-bolus therapy with insulin detemir / insulin aspart or human NPH insulin / human regular insulin in random order. The major inclusion criterion is history of two or more episodes of severe hypoglycaemia in the preceding year. Discussion In contrast to almost all other studies in this field the HypoAna Trial includes only patients with major problems with hypoglycaemia. The HypoAna Trial will elucidate whether basal-bolus regimen with short-acting and long-acting insulin analogues in comparison with human insulin are superior in reducing occurrence of severe hypoglycaemic episodes in hypoglycaemia prone patients with type 1 diabetes. http://www.clinicaltrials.gov: NCT00346996. PMID:22727048

An overview of the impact of rare disease characteristics on research methodology.

PubMed

Whicher, Danielle; Philbin, Sarah; Aronson, Naomi

2018-01-19

About 30 million individuals in the United States are living with a rare disease, which by definition have a prevalence of 200,000 or fewer cases in the United States ([National Organization for Rare Disorders], [About NORD], [2016]). Disease heterogeneity and geographic dispersion add to the difficulty of completing robust studies in small populations. Improving the ability to conduct research on rare diseases would have a significant impact on population health. The purpose of this paper is to raise awareness of methodological approaches that can address the challenges to conducting robust research on rare diseases. We conducted a landscape review of available methodological and analytic approaches to address the challenges of rare disease research. Our objectives were to: 1. identify algorithms for matching study design to rare disease attributes and the methodological approaches applicable to these algorithms; 2. draw inferences on how research communities and infrastructure can contribute to the efficiency of research on rare diseases; and 3. to describe methodological approaches in the rare disease portfolio of the Patient-Centered Outcomes Research Institute (PCORI), a funder promoting both rare disease research and research infrastructure. We identified three algorithms for matching study design to rare disease or intervention characteristics (Gagne, et.al, BMJ 349:g6802, 2014); (Gupta, et.al, J Clin Epidemiol 64:1085-1094, 2011); (Cornu, et. al, Orphet J Rare Dis 8:48,2012) and summarized the applicable methodological and analytic approaches. From this literature we were also able to draw inferences on how an effective research infrastructure can set an agenda, prioritize studies, accelerate accrual, catalyze patient engagement and terminate poorly performing studies. Of the 24 rare disease projects in the PCORI portfolio, 11 are randomized controlled trials (RCTs) using standard designs. Thirteen are observational studies using case-control, prospective cohort, or natural history designs. PCORI has supported the development of 9 Patient-Powered Research Networks (PPRNs) focused on rare diseases. Matching research design to attributes of rare diseases and interventions can facilitate the completion of RCTs that are adequately powered. An effective research infrastructure can improve efficiency and avoid waste in rare disease research. Our review of the PCORI research portfolio demonstrates that it is feasible to conduct RCTs in rare disease. However, most of these studies are using standard RCT designs. This suggests that use of a broader array of methodological approaches to RCTs --such as adaptive trials, cross-over trials, and early escape designs can improve the productivity of robust research in rare diseases.

Synchronized navigation of current and prior studies using image registration improves radiologist's efficiency.

PubMed

Forsberg, Daniel; Gupta, Amit; Mills, Christopher; MacAdam, Brett; Rosipko, Beverly; Bangert, Barbara A; Coffey, Michael D; Kosmas, Christos; Sunshine, Jeffrey L

2017-03-01

The purpose of this study was to investigate how the use of multi-modal rigid image registration integrated within a standard picture archiving and communication system affects the efficiency of a radiologist while performing routine interpretations of cases including prior examinations. Six radiologists were recruited to read a set of cases (either 16 neuroradiology or 14 musculoskeletal cases) during two crossover reading sessions. Each radiologist read each case twice, one time with synchronized navigation, which enables spatial synchronization across examinations from different study dates, and one time without. Efficiency was evaluated based upon time to read a case and amount of scrolling while browsing a case using Wilcoxon signed rank test. Significant improvements in efficiency were found considering either all radiologists simultaneously, the two sections separately and the majority of individual radiologists for time to read and for amount of scrolling. The relative improvement for each individual radiologist ranged from 4 to 32% for time to read and from 14 to 38% for amount of scrolling. Image registration providing synchronized navigation across examinations from different study dates provides a tool that enables radiologists to work more efficiently while reading cases with one or more prior examinations.

Comparison of two kinds of interface, based on guided navigation or usability principles, for improving the adoption of computerized decision support systems: application to the prescription of antibiotics.

PubMed

Tsopra, Rosy; Jais, Jean-Philippe; Venot, Alain; Duclos, Catherine

2014-02-01

It is important to consider the way in which information is presented by the interfaces of clinical decision support systems, to favor the adoption of these systems by physicians. Interface design can focus on decision processes (guided navigation) or usability principles. The aim of this study was to compare these two approaches in terms of perceived usability, accuracy rate, and confidence in the system. We displayed clinical practice guidelines for antibiotic treatment via two types of interface, which we compared in a crossover design. General practitioners were asked to provide responses for 10 clinical cases and the System Usability Scale (SUS) for each interface. We assessed SUS scores, the number of correct responses, and the confidence level for each interface. SUS score and percentage confidence were significantly higher for the interface designed according to usability principles (81 vs 51, p=0.00004, and 88.8% vs 80.7%, p=0.004). The percentage of correct responses was similar for the two interfaces. The interface designed according to usability principles was perceived to be more usable and inspired greater confidence among physicians than the guided navigation interface. Consideration of usability principles in the construction of an interface--in particular 'effective information presentation', 'consistency', 'efficient interactions', 'effective use of language', and 'minimizing cognitive load'--seemed to improve perceived usability and confidence in the system.

Bioequivalence evaluation of two brands of amoxicillin/clavulanic acid 250/125 mg combination tablets in healthy human volunteers: use of replicate design approach.

PubMed

Idkaidek, Nasir M; Al-Ghazawi, Ahmad; Najib, Naji M

2004-12-01

The purpose of this study was to apply a replicate design approach to a bioequivalence study of amoxicillin/clavulanic acid combination following a 250/125 mg oral dose to 23 subjects, and to compare the analysis of individual bioequivalence with average bioequivalence. This was conducted as a 2-treatment 2-sequence 4-period crossover study. Average bioequivalence was shown, while the results from the individual bioequivalence approach had no success in showing bioequivalence. In conclusion, the individual bioequivalence approach is a strong statistical tool to test for intra-subject variances and also subject-by-formulation interaction variance compared with the average bioequivalence approach. copyright (c) 2004 John Wiley & Sons, Ltd.

Local and sex-specific biases in crossover vs. noncrossover outcomes at meiotic recombination hot spots in mice

PubMed Central

de Boer, Esther; Jasin, Maria; Keeney, Scott

2015-01-01

Meiotic recombination initiated by programmed double-strand breaks (DSBs) yields two types of interhomolog recombination products, crossovers and noncrossovers, but what determines whether a DSB will yield a crossover or noncrossover is not understood. In this study, we analyzed the influence of sex and chromosomal location on mammalian recombination outcomes by constructing fine-scale recombination maps in both males and females at two mouse hot spots located in different regions of the same chromosome. These include the most comprehensive maps of recombination hot spots in oocytes to date. One hot spot, located centrally on chromosome 1, behaved similarly in male and female meiosis: Crossovers and noncrossovers formed at comparable levels and ratios in both sexes. In contrast, at a distal hot spot, crossovers were recovered only in males even though noncrossovers were obtained at similar frequencies in both sexes. These findings reveal an example of extreme sex-specific bias in recombination outcome. We further found that estimates of relative DSB levels are surprisingly poor predictors of relative crossover frequencies between hot spots in males. Our results demonstrate that the outcome of mammalian meiotic recombination can be biased, that this bias can vary depending on location and cellular context, and that DSB frequency is not the only determinant of crossover frequency. PMID:26251527

Spectropolarimetry of magnetic stars. IV. The crossover effect.

NASA Astrophysics Data System (ADS)

Mathys, G.

1995-01-01

This paper is devoted to the study of the crossover effect in magnetic Ap stars. It is shown that this effect can be measured by the second order moment about their centre of the profiles of spectral lines recorded in the Stokes parameter V. The interpretation of these measurements in terms of magnetic field is developed. It is shown that one can derive from them a quantity called the mean asymmetry of the longitudinal magnetic field, which is the first moment of the component of the magnetic field along the line of sight, about the plane defined by the line of sight and the stellar rotation axis. The consistency of the determination of this quantity with that of the mean longitudinal magnetic field from measurements of wavelength shifts of lines between right and left circular polarization is demonstrated. This technique of analysis is applied to observations of a sample of 29 stars, among which 10 have a detectable crossover effect. For 8 of them, the available observational data allow the study of the variations of the asymmetry of the longitudinal field with rotation phase. In most cases, this variation is sinusoidal and essentially symmetric about 0, and it occurs in quadrature with the variation of the mean longitudinal field. A more complex behaviour is definitely observed in HD 147010 and HD 175362, where the variation of the asymmetry of the longitudinal field is better represented by the superposition of two sinusoids, one with the rotation frequency of the star, and the other with twice that frequency.

Short-term departures from an optimum ambient temperature are associated with increased risk of out-of-hospital cardiac arrest.

PubMed

Dahlquist, Marcus; Raza, Auriba; Bero-Bedada, Getahun; Hollenberg, Jacob; Lind, Tomas; Orsini, Nicola; Sjögren, Bengt; Svensson, Leif; Ljungman, Petter L

2016-07-01

Associations have been reported between daily ambient temperature and all-cause and cardiovascular mortality. However, the potential harmful effect of temperature on out-of-hospital cardiac arrest (OHCA) is insufficiently studied. The objective of this study was to investigate the short-term association between ambient temperature and the occurrence of OHCA. In 5961 cases of OHCAs treated by Emergency Medical Service occurring in Stockholm County we investigated the association between the preceding 24-h and 1h mean ambient temperature, obtained from a fixed monitoring station, and OHCA using a time-stratified case-crossover design. We observed a V-shaped relationship between preceding mean 24-h and 1-h ambient temperature and the occurrence of OHCAs. For mean 24-h temperature we observed an odds ratio (OR) of 1.05 (1.00-1.11) for each 5°C below the optimum temperature and 1.05 (0.96-1.18) for each 5°C above the optimum. We observed similar results for 1-h mean temperature exposure. Results for temperatures above the optimum temperature showed evidence of confounding by ozone. Ambient temperature below an optimum temperature was associated with increased risk of OHCA in Stockholm. Temperature above an optimum temperature was not significantly associated with OHCA. Copyright © 2016 Elsevier GmbH. All rights reserved.

Does hot weather affect work-related injury? A case-crossover study in Guangzhou, China.

PubMed

Sheng, Rongrong; Li, Changchang; Wang, Qiong; Yang, Lianping; Bao, Junzhe; Wang, Kaiwen; Ma, Rui; Gao, Chuansi; Lin, Shao; Zhang, Ying; Bi, Peng; Fu, Chuandong; Huang, Cunrui

2018-04-01

Despite increasing concerns about the health effects of climate change, the extent to which workers are affected by hot weather is not well documented. This study aims to investigate the association between high temperatures and work-related injuries using data from a large subtropical city in China. We used workers' compensation claims to identify work-related injuries in Guangzhou, China during 2011-2012. To feature the heat effect, the study period was restricted to the warm seasons in Guangzhou (1 May-31 October). We conducted a time-stratified case-crossover study to examine the association between ambient outdoor temperatures, including daily maximum and minimum temperatures, and cases of work-related injury. The relationships were assessed using conditional Poisson regression models. Overall, a total of 5418 workers' compensation claims were included over the study period. Both maximum and minimum temperatures were significantly associated with work-related injuries, but associations varied by subgroup. One °C increase in maximum temperature was associated with a 1.4% (RR = 1.014, 95%CIs 1.012-1.017) increase in daily injury claims. Significant associations were seen for male and middle-aged workers, workers in small and medium-sized enterprises, and those working in manufacturing sector. And 1 °C increase in minimum temperature was associated with 1.7% (RR = 1.017, 95%CIs 1.012-1.021) increase in daily injury claims. Significant associations were observed for female and middle-aged workers, workers in large-sized enterprises, and those working in transport and construction sectors. We found a higher risk of work-related injuries due to hot weather in Guangzhou, China. This study provides important epidemiological evidence for policy-makers and industry that may assist in the formulation of occupational safety and climate adaptation strategies. Copyright © 2018 Elsevier GmbH. All rights reserved.

A Crossover Study of Risperidone in Children, Adolescents and Adults with Mental Retardation

ERIC Educational Resources Information Center

Hellings, Jessica A.; Zarcone, Jennifer R.; Reese, R. Matthew; Valdovinos, Maria G.; Marquis, Janet G.; Fleming, Kandace K.; Schroeder, Stephen R.

2006-01-01

Risperidone has shown safety and efficacy for aggressive and destructive behaviors in short-term studies. This longer-duration study includes a broad sample. Forty subjects, aged 8-56 years (mean=22), all with mental retardation and 36 with autism spectrum disorders participated in this 22-week crossover study, with 24 weeks of open maintenance…

Spinal Muscular Atrophy Biomarker Measurements from Blood Samples in a Clinical Trial of Valproic Acid in Ambulatory Adults

PubMed Central

Renusch, Samantha R.; Harshman, Sean; Pi, Hongyang; Workman, Eileen; Wehr, Allison; Li, Xiaobai; Prior, Thomas W.; Elsheikh, Bakri H.; Swoboda, Kathryn J.; Simard, Louise R.; Kissel, John T.; Battle, Daniel; Parthun, Mark R.; Freitas, Michael A.; Kolb, Stephen J.

2015-01-01

Abstract Background: Clinical trials of therapies for spinal muscular atrophy (SMA) that are designed to increase the expression the SMN protein ideally include careful assessment of relevant SMN biomarkers. Objective: In the SMA VALIANT trial, a recent double-blind placebo-controlled crossover study of valproic acid (VPA) in ambulatory adult subjects with SMA, we investigated relevant pharmacodynamic biomarkers in blood samples from SMA subjects by direct longitudinal measurement of histone acetylation and SMN mRNA and protein levels in the presence and absence of VPA treatment. Methods: Thirty-three subjects were randomized to either VPA or placebo for the first 6 months followed by crossover to the opposite arm for an additional 6 months. Outcome measures were compared between the two treatments (VPA and placebo) using a standard crossover analysis. Results: A significant increase in histone H4 acetylation was observed with VPA treatment (p = 0.005). There was insufficient evidence to suggest a treatment effect with either full length or truncated SMN mRNA transcript levels or SMN protein levels. Conclusions: These measures were consistent with the observed lack of change in the primary clinical outcome measure in the VALIANT trial. These results also highlight the added benefit of molecular and pharmacodynamic biomarker measurements in the interpretation of clinical trial outcomes. PMID:27858735

Predictive Factors for Patients Undergoing ASD Device Occlusion Who "Crossover" to Surgery.

PubMed

Mulukutla, Venkatachalam; Qureshi, Athar M; Pignatelli, Ricardo; Ing, Frank F

2018-03-01

The aim of this study was to define characteristics of those patients who are referred for device closure of an Atrial septal defect (ASD), but identified to "crossover" surgery. All patients who underwent surgical and device (Amplatzer or Helex occluder) closures of secundum ASDs from 2001 to 2010 were reviewed and organized into three groups: surgical closure, device closure, and "crossover" group. 369 patients underwent ASD closure (265 device, 104 surgical). 42 of the 265 patients referred for device closure "crossed over" to the surgical group at various stages of the catheterization procedure. The device group had defect size measuring 14.2 mm (mean) and an ASD index (Defect Size (mm)/BSA) of 14.0 compared to the corresponding values in the surgical group (20.1 mm, ASD index 25.9) (P < 0.001) and in the "crossover" group (20.7 mm, 22.6 ASD index) (P < 0.001). 79 patients in the device group had a deficient rim, and 86% were located in the retroaortic region. 33 patients in the "crossover" group had deficient rims with 70% deficiency in the posterior/inferior rim. The device group with deficient rims had an ASD index of 14.7 compared with the crossover group ASD index of 23.8 (P < 0.001). Comparing the device and "crossover" groups, an ASD index greater than 23.7 had a 90% specificity in "crossing over" to surgery. The crossover and surgical groups had statistically larger ASD defect size indexes compared with the device group. Deficient rim in the posterior/inferior rim is associated with a large ASD size index which is a predictive factor for crossing over to surgery. Catheterization did not negatively impact surgical results in the "crossover" group.

Aged Garlic Extract Improves Adiponectin Levels in Subjects with Metabolic Syndrome: A Double-Blind, Placebo-Controlled, Randomized, Crossover Study

PubMed Central

Gómez-Arbeláez, Diego; Lahera, Vicente; Oubiña, Pilar; Valero-Muñoz, Maria; de las Heras, Natalia; Rodríguez, Yudy; García, Ronald Gerardo; Camacho, Paul Anthony; López-Jaramillo, Patricio

2013-01-01

Background. Garlic (Allium sativum) has been shown to have important benefits in individuals at high cardiovascular risk. The aim of the present study was to evaluate the effects of the administration of aged garlic extract (AGE) on the risk factors that constitute the cluster of metabolic syndrome (MS). Methods and Design. Double-blind, crossover, randomized, placebo-controlled clinical trial to assess the effect of 1.2 g/day of AGE (Kyolic), for 24 weeks of treatment (12 weeks of AGE and 12 weeks of placebo), on subjects with MS. Results. The administration of AGE increased the plasma levels of adiponectin (P = 0.027). No serious side effects associated with the intervention were reported. Conclusion. The present results have shown for the first time that the administration of AGE for 12 weeks increased plasma adiponectin levels in patients with MS. This suggests that AGE might be a useful, novel, nonpharmacological therapeutic intervention to increase adiponectin and to prevent cardiovascular (CV) complications in individuals with MS. PMID:23533302

Polydextrose: its impact on short-term food intake and subjective feelings of satiety in males-a randomized controlled cross-over study.

PubMed

Ranawana, Viren; Muller, Adelaide; Henry, C Jeya K

2013-04-01

Polydextrose is a low-calorie highly branched-chain glucose polymer that is poorly digested in the upper gastrointestinal tract and therefore demonstrates fibre-like properties. Fibre has been shown to increase satiety and possibly reduce food intake. Therefore, the objective of the current study was to examine the effects of polydextrose on short-term satiety and energy intake. In a repeated-measures randomized blind cross-over design, 26 healthy males consumed a 400-g fruit smoothie containing 12 g (3 %) of polydextrose, and a buffet lunch 60 min after the smoothie. Motivational ratings for satiety and palatability and lunch energy intake were measured. The effects of the polydextrose-containing smoothie were compared against a polydextrose-free control smoothie. Polydextrose did not significantly alter the taste and palatability of the fruit smoothie. Consuming the polydextrose-containing smoothie resulted in a significantly lower energy intake at lunch (102 kcal less) compared to the control. Polydextrose may be a good fortificant for reducing short-term food intake.

Short-term effect of fine particulate air pollution on daily mortality: a case-crossover study in a tropical city, Kaohsiung, Taiwan.

PubMed

Tsai, Shang-Shyue; Chen, Chih-Cheng; Yang, Chun-Yuh

2014-01-01

Many studies have examined the short-term effects of air pollution on frequency of daily mortality over the past two decades. However, information on the relationship between levels of fine particles (PM(2.5)) and daily mortality is relatively sparse due to limited availability of monitoring data. Further the results are inconsistent. This study was undertaken to determine whether there was an association between PM(2.5) levels and daily mortality rate in Kaohsiung, Taiwan, a large industrial city with a tropical climate. Daily mortality rate, air pollution parameters, and weather data for Kaohsiung were obtained for the period from 2006 through 2008. The relative risk of daily mortality occurrence was estimated using a time-stratified case-crossover approach, controlling for (1) weather variables, (2) day of the week, (3) seasonality, and (4) long-term time trends. For the single-pollutant model (without adjustment for other pollutants), no significant effects were found between PM(2.5) and frequency of daily mortality on warm days (≥25°C). On cool days, PM(2.5) showed significant correlation with increased risk of mortality rate for all causes and circulatory diseases in single-pollutant model. There was no indication of an association between PM(2.5) and deaths due to respiratory diseases. The relationship appeared to be stronger on cool days. This study provided evidence of associations between short-term exposure to PM(2.5) and elevated risk of death for all cause and circulatory diseases.

Experience and challenges presented by a multicenter crossover study of combination analgesic therapy for the treatment of painful HIV-associated polyneuropathies

PubMed Central

Harrison, Taylor; Miyahara, Sachiko; Lee, Anthony; Evans, Scott; Bastow, Barbara; Simpson, David; Gilron, Ian; Dworkin, Robert; Daar, Eric S.; Wieclaw, Linda; Clifford, David B.

2014-01-01

Objective There is limited evidence for efficacy of analgesics as monotherapy for neuropathic pain associated with HIV-associated polyneuropathies, in spite of demonstrated efficacy in other neuropathic pain conditions. We evaluated the tolerability and analgesic efficacy of duloxetine, methadone, and the combination of duloxetine-methadone compared to placebo. Design This study was a phase II, randomized, double blind, placebo-controlled, four-period crossover multi-center study of analgesic therapy for patients with at least moderate neuropathic pain due to HIV-associated polyneuropathy. Duloxetine, methadone, combination duloxetine-methadone, and placebo were administered in four different possible sequences. The primary outcome measure was mean pain intensity (MPI) measured daily in a study-supplied pain diary. Results A total of 15 patients were enrolled from 8 study sites and 8 patients completed the entire trial. Study treatments failed to show statistically significant change in MPI compared to placebo. Adverse events were frequent and associated with high rates of drug discontinuation and study drop-out. Conclusions Challenges with participant recruitment and poor retention precluded trial completion to its planned targets, limiting our evaluation of the analgesic efficacy of the study treatments. Challenges to successful completion of this study and lessons learned are discussed. PMID:23565581

REFERENT SELECTION IN CASE-CROSSOVER ANALYSES OF HEALTH EFFECTS OF AIR POLLUTION. (R825173)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

Effect of Crossover in Oncology Clinical Trials on Evidence Levels in Early Benefit Assessment in Germany.

PubMed

Isbary, Georg; Staab, Thomas R; Amelung, Volker E; Dintsios, Charalabos-Markos; Iking-Konert, Christof; Nesurini, Sonja Mariotti; Walter, Miriam; Ruof, Jörg

2018-06-01

In oncology clinical trials, crossover is used frequently but may lead to uncertainties regarding treatment effects. To investigate the handling of evidence from crossover trials by the European Medicines Agency (EMA) and the German Federal Joint Committee (G-BA). For oncology medicines with early benefit assessments before January 2015, presence of crossover, clinical data, EMA requests for additional data, and G-BA benefit ratings/evidence levels were analyzed from manufacturers' dossiers, G-BA appraisals, European Public Assessment Reports, and original publications. Eleven of 21 benefit assessments included crossover trials. Significant intergroup differences (P < 0.05) in overall survival (OS) were noted in 7 of 11 trials with and 7 of 10 without crossover. For 6 of 11 medicines with crossover, these were demonstrated before crossover. Treatment effects generally worsened with increasing proportions of crossover. The EMA requested additional data more frequently if crossover was performed, particularly if no OS data were available before crossover. The G-BA granted a considerable benefit to 73% of medicines with crossover and 40% of those without. Evidence levels were intermediate for 50% and 75%, respectively. None of the medicines received the highest evidence level. In G-BA appraisals, oncology medicines with crossover received better additional benefit ratings, but were assigned lower evidence levels, than those without. The five medicines with crossover after progression were assigned lower evidence levels than the six medicines with crossover after demonstration of superior OS, indicating that the way in which crossover is implemented may be one factor influencing the assignment of evidence levels by the G-BA. Copyright © 2018 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.

Using environmental engineering to increase hand hygiene compliance: a cross-over study protocol

PubMed Central

Schmidtke, Kelly Ann; Aujla, Navneet; Marshall, Tom; Hussain, Abid; Hodgkinson, Gerard P; Arheart, Kristopher; Marti, Joachim; Birnbach, David J; Vlaev, Ivo

2017-01-01

Introduction Compliance with hand hygiene recommendations in hospital is typically less than 50%. Such low compliance inevitably contributes to hospital-acquired infections that negatively affect patients’ well-being and hospitals’ finances. The design of the present study is predicated on the assumption that most people who fail to clean their hands are not doing so intentionally, they just forget. The present study will test whether psychological priming can be used to increase the number of people who clean their hands on entering a ward. Here, we present the protocol for this study. Methods and analysis The study will use a randomised cross-over design. During the study, each of four wards will be observed during four conditions: olfactory prime, visual prime, both primes and neither prime. Each condition will be experienced for 42 days followed by a 7-day washout period (total duration of trial=189 days). We will record the number of people who enter each ward and whether they clean their hands during observation sessions, the amount of cleaning material used from the dispensers each week and the number of hospital-acquired infections that occur in each period. The outcomes will be compared using a regression analysis. Following the initial trail, the most effective priming condition will be rolled out for 3 months in all the wards. Ethics and dissemination Research ethics approval was obtained from the South Central—Oxford C Research Ethics Committee (16/SC/0554), the Health Regulatory Authority and the sponsor. Trial registration number ISRCTN (15397624); Edge ID 86357. PMID:28893752

A mission-oriented orbit design method of remote sensing satellite for region monitoring mission based on evolutionary algorithm

NASA Astrophysics Data System (ADS)

Shen, Xin; Zhang, Jing; Yao, Huang

2015-12-01

Remote sensing satellites play an increasingly prominent role in environmental monitoring and disaster rescue. Taking advantage of almost the same sunshine condition to same place and global coverage, most of these satellites are operated on the sun-synchronous orbit. However, it brings some problems inevitably, the most significant one is that the temporal resolution of sun-synchronous orbit satellite can't satisfy the demand of specific region monitoring mission. To overcome the disadvantages, two methods are exploited: the first one is to build satellite constellation which contains multiple sunsynchronous satellites, just like the CHARTER mechanism has done; the second is to design non-predetermined orbit based on the concrete mission demand. An effective method for remote sensing satellite orbit design based on multiobjective evolution algorithm is presented in this paper. Orbit design problem is converted into a multi-objective optimization problem, and a fast and elitist multi-objective genetic algorithm is utilized to solve this problem. Firstly, the demand of the mission is transformed into multiple objective functions, and the six orbit elements of the satellite are taken as genes in design space, then a simulate evolution process is performed. An optimal resolution can be obtained after specified generation via evolution operation (selection, crossover, and mutation). To examine validity of the proposed method, a case study is introduced: Orbit design of an optical satellite for regional disaster monitoring, the mission demand include both minimizing the average revisit time internal of two objectives. The simulation result shows that the solution for this mission obtained by our method meet the demand the users' demand. We can draw a conclusion that the method presented in this paper is efficient for remote sensing orbit design.

Interaction Effects of Temperature and Ozone on Lung Function and Markers of Systemic Inflammation, Coagulation, and Fibrinolysis: A Crossover Study of Healthy Young Volunteers

PubMed Central

Kahle, Juliette J.; Neas, Lucas M.; Devlin, Robert B.; Case, Martin W.; Schmitt, Michael T.; Madden, Michael C.

2014-01-01

Background: Trends in climate suggest that extreme weather events such as heat waves will become more common. High levels of the gaseous pollutant ozone are associated with elevated temperatures. Ozone has been associated with respiratory diseases as well as cardiovascular morbidity and mortality and can reduce lung function and alter systemic markers of fibrinolysis. The interaction between ozone and temperature is unclear. Methods: Sixteen healthy volunteers were exposed in a randomized crossover study to 0.3 ppm ozone and clean air for 2 hr at moderate (22°C) temperature and again at an elevated temperature (32.5°C). In each case lung function was performed and blood taken before and immediately after exposure and the next morning. Results: Ozone exposure at 22°C resulted in a decrease in markers of fibrinolysis the next day. There was a 51.8% net decrease in PAI-1 (plasminogen activator inhibitor-1), a 12.1% net decrease in plasminogen, and a 17.8% net increase in D-dimer. These significantly differed from the response at 32.5°C, where there was a 44.9% (p = 0.002) and a 27.9% (p = 0.001) increase in PAI-1 and plasminogen, respectively, and a 12.5% (p = 0.042) decrease in D-dimer. In contrast, decrements in lung function following ozone exposure were comparable at both moderate and elevated temperatures (forced expiratory volume in 1 sec, –12.4% vs. –7.5%, p > 0.05). No changes in systemic markers of inflammation were observed for either temperature. Conclusion: Ozone-induced systemic but not respiratory effects varied according to temperature. Our study suggests that at moderate temperature ozone may activate the fibrinolytic pathway, while at elevated temperature ozone may impair it. These findings provide a biological basis for the interaction between temperature and ozone on mortality observed in some epidemiologic studies. Citation: Kahle JJ, Neas LM, Devlin RB, Case MW, Schmitt MT, Madden MC, Diaz-Sanchez D. 2015. Interaction effects of temperature and ozone on lung function and markers of systemic inflammation, coagulation, and fibrinolysis: a crossover study of healthy young volunteers. Environ Health Perspect 123:310–316; http://dx.doi.org/10.1289/ehp.1307986 PMID:25514459

Prevention of emergency physician migratory contamination in a cluster randomized trial to increase tissue plasminogen activator use in stroke (the INSTINCT trial).

PubMed

Weston, Victoria C; Meurer, William J; Frederiksen, Shirley M; Fox, Allison K; Scott, Phillip A

2014-12-01

Cluster randomized trials (CRTs) are increasingly used to evaluate quality improvement interventions aimed at health care providers. In trials testing emergency department (ED) interventions, migration of emergency physicians (EPs) between hospitals is an important concern, as contamination may affect both internal and external validity. We hypothesized that geographically isolating EDs would prevent migratory contamination in a CRT designed to increase ED delivery of tissue plasminogen activator (tPA) in stroke (the INSTINCT trial). INSTINCT was a prospective, cluster randomized, controlled trial. Twenty-four Michigan community hospitals were randomly selected in matched pairs for study. Contamination was defined at the cluster level, with substantial contamination defined a priori as greater than 10% of EPs affected. Nonadherence, total crossover (contamination+nonadherence), migration distance, and characteristics were determined. Three hundred seven EPs were identified at all sites. Overall, 7 (2.3%) changed study sites. One moved between control sites, leaving 6 (2.0%) total crossovers. Of these, 2 (0.7%) moved from intervention to control (contamination); and 4 (1.3%) moved from control to intervention (nonadherence). Contamination was observed in 2 of 12 control sites, with 17% and 9% contamination of the total site EP workforce at follow-up, respectively. Average migration distance was 42 miles for all EPs moving in the study and 35 miles for EPs moving from intervention to control sites. The mobile nature of EPs should be considered in the design of quality improvement CRTs. Increased reporting of contamination in CRTs is encouraged to clarify thresholds and facilitate CRT design. Copyright © 2014 Elsevier Inc. All rights reserved.

Axillary reverse mapping with indocyanine green or isosulfan blue demonstrate similar crossover rates to radiotracer identified sentinel nodes.

PubMed

Foster, Deshka; Choy, Nicole; Porter, Catherine; Ahmed, Shushmita; Wapnir, Irene

2018-03-01

Sentinel lymph node (SLN) resection is imperative for breast cancer staging. Axillary reverse mapping (ARM) can preserve arm draining nodes and lymphatics during surgery. ARM is generally performed with isosulfan blue (ISB), restricting its use for concurrent SLN biopsy. Indocyanine green (ICG) could serve as an alternative to ISB for ARM procedures. SLN mapping and biopsy was performed via periareolar injection of 99 technetium-sulfur colloid ( 99m TcSc, TSC). ISB and ICG were injected in the upper arm. Blue-stained lymphatics or nodes were visualized in the axilla; ICG was identified using the SPY Elite® system. Twenty-three patients underwent SLN biopsy with or without axillary node dissection and ARM procedures. Twenty of these patients had at least one hot node; 12 patients had SLNs that were only hot, 6 hot/blue/fluorescent, and 2 hot/fluorescent. Overall, crossover of ARM agents with SLNs occurred in 8 cases. Inspection of the axillary cavity after SLN biopsy revealed fluorescent lymphatics and nodes remaining in 14 and 7 patients, respectively. Blue lymphatics and blue nodes were detected in fewer cases. Nearly one-third of patients showed crossover between breast and arm draining nodes, which provides insight as to why some patients develop lymphedema symptoms after SLN biopsy. ICG and ISB identify similar numbers of SLNs. As such ICG could substitute for ISB in ARM procedures. © 2017 Wiley Periodicals, Inc.

Unravelling the spin-state of solvated [Fe(bpp)2]2+ spin-crossover complexes: structure-function relationship.

PubMed

Giménez-López, Maria Del Carmen; Clemente-León, Miguel; Giménez-Saiz, Carlos

2018-05-23

This paper reports firstly the syntheses, crystal structures, and thermal and magnetic properties of spin crossover salts of formulae [Fe(bpp)2]3[Cr(CN)6]2·13H2O (1) and [Fe(bpp)2][N(CN)2]2·H2O (2) (bpp = 2,6-bis(pyrazol-3-yl)pyridine) exhibiting hydrogen-bonded networks of low-spin [Fe(bpp)2]2+ complexes and [Cr(CN)6]3- or [N(CN)2]- anions, with solvent molecules located in the voids. Desolvation of 1 is accompanied by a complete low-spin (LS) to a high-spin (HS) transformation that becomes reversible after rehydration by exposing the sample to the humidity of air. The influence of the lattice water on the magnetic properties of spin-crossover [Fe(bpp)2]X2 complex salts has been documented. In most cases, it stabilises the LS state over the HS one. In other cases, it is rather the contrary. The second part of this paper is devoted to unravelling the reasons why the lattice solvent stabilises one form over the other through magneto-structural correlations of [Fe(bpp)2]2+ salts bearing anions with different charge/size ratios (Xn-). The [Fe(bpp)2]2+ stacking explaining these two different behaviours is correlated here with the composition of the second coordination sphere of the Fe centers and the ability of these anions to form hydrogen bonds and/or π-π stacking interactions between them or the bpp ligand.

OML: optical maskless lithography for economic design prototyping and small-volume production

NASA Astrophysics Data System (ADS)

Sandstrom, Tor; Bleeker, Arno; Hintersteiner, Jason; Troost, Kars; Freyer, Jorge; van der Mast, Karel

2004-05-01

The business case for Maskless Lithography is more compelling than ever before, due to more critical processes, rising mask costs and shorter product cycles. The economics of Maskless Lithography gives a crossover volume from Maskless to mask-based lithography at surprisingly many wafers per mask for surprisingly few wafers per hour throughput. Also, small-volume production will in many cases be more economical with Maskless Lithography, even when compared to "shuttle" schemes, reticles with multiple layers, etc. The full benefit of Maskless Lithography is only achievable by duplicating processes that are compatible with volume production processes on conventional scanners. This can be accomplished by the integration of pattern generators based on spatial light modulator technology with state-of-the-art optical scanner systems. This paper reports on the system design of an Optical Maskless Scanner in development by ASML and Micronic: small-field optics with high demagnification, variable NA and illumination schemes, spatial light modulators with millions of MEMS mirrors on CMOS drivers, a data path with a sustained data flow of more than 250 GPixels per second, stitching of sub-fields to scanner fields, and rasterization and writing strategies for throughput and good image fidelity. Predicted lithographic performance based on image simulations is also shown.

Cooperative optimization of reconfigurable machine tool configurations and production process plan

NASA Astrophysics Data System (ADS)

Xie, Nan; Li, Aiping; Xue, Wei

2012-09-01

The production process plan design and configurations of reconfigurable machine tool (RMT) interact with each other. Reasonable process plans with suitable configurations of RMT help to improve product quality and reduce production cost. Therefore, a cooperative strategy is needed to concurrently solve the above issue. In this paper, the cooperative optimization model for RMT configurations and production process plan is presented. Its objectives take into account both impacts of process and configuration. Moreover, a novel genetic algorithm is also developed to provide optimal or near-optimal solutions: firstly, its chromosome is redesigned which is composed of three parts, operations, process plan and configurations of RMTs, respectively; secondly, its new selection, crossover and mutation operators are also developed to deal with the process constraints from operation processes (OP) graph, otherwise these operators could generate illegal solutions violating the limits; eventually the optimal configurations for RMT under optimal process plan design can be obtained. At last, a manufacturing line case is applied which is composed of three RMTs. It is shown from the case that the optimal process plan and configurations of RMT are concurrently obtained, and the production cost decreases 6.28% and nonmonetary performance increases 22%. The proposed method can figure out both RMT configurations and production process, improve production capacity, functions and equipment utilization for RMT.

Association of Ambient Fine Particles With Out-of-Hospital Cardiac Arrests in New York City

PubMed Central

Silverman, Robert A.; Ito, Kazuhiko; Freese, John; Kaufman, Brad J.; De Claro, Danilynn; Braun, James; Prezant, David J.

2010-01-01

Cardiovascular morbidity has been associated with particulate matter (PM) air pollution, although the relation between pollutants and sudden death from cardiac arrest has not been established. This study examined associations between out-of-hospital cardiac arrests and fine PM (of aerodynamic diameter ≤2.5 μm, or PM2.5), ozone, nitrogen dioxide, sulfur dioxide, and carbon monoxide in New York City. The authors analyzed 8,216 out-of-hospital cardiac arrests of primary cardiac etiology during the years 2002–2006. Time-series and case-crossover analyses were conducted, controlling for season, day-of-week, same-day, and delayed/apparent temperature. An increased risk of cardiac arrest in time-series (relative risk (RR) = 1.06, 95% confidence interval (CI): 1.02, 1.10) and case-crossover (RR = 1.04, 95% CI: 0.99, 1.08) analysis for a PM2.5 increase of 10 μg/m3 in the average of 0- and 1-day lags was found. The association was significant in the warm season (RR = 1.09, 95% CI: 1.03, 1.15) but not the cold season (RR = 1.01, 95% CI: 0.95, 1.07). Associations of cardiac arrest with other pollutants were weaker. These findings, consistent with studies implicating acute cardiovascular effects of PM, support a link between PM2.5 and out-of-hospital cardiac arrests. Since few individuals survive an arrest, air pollution control may help prevent future cardiovascular mortality. PMID:20729350

Extreme Precipitation and Emergency Room Visits for Influenza in Massachusetts: A Case-Crossover Analysis

EPA Science Inventory

BACKGROUND: Influenza peaks during the wintertime in temperate regions and during the annual rainy season in tropical regions – however reasons for the observed differences in disease ecology are poorly understood. We hypothesize that episodes of extreme precipitation also result...

Flooding and Health Care Visits for Clostridium Difficile Infection: A Case-Crossover Analysis

EPA Science Inventory

Floods can contaminate potable water and other resources, thus increasing the potential for fecal-oral transmission of pathogens. Clostridium difficile is a bacterium that can spread by water and cause acute gastrointestinal illness. It often affects older adults who are hospital...

A systematic review identifies shortcomings in the reporting of crossover trials in chronic painful conditions.

PubMed

Straube, Sebastian; Werny, Benedikt; Friede, Tim

2015-12-01

To investigate the reporting of study features of interest in abstracts and full texts of journal publications of crossover trials in chronic painful conditions. Systematic review based on a MEDLINE (PubMed) search (January 1990-August 2014). Ninety-eight publications on crossover studies with 3,513 study participants were eligible for inclusion. Double-blind status and randomized allocation to treatment groups are commonly reported in both abstracts and full texts (90 of 98 publications and 82 of 98 publications, respectively). Adverse events are reported in both abstract and full text in 49 of 98 publications and in the full text only in 44 of 98. A breakdown of results by treatment period is provided only in 23 of 98 publications, and if so, is reported only in the full text, never in the abstract. There is a time trend for the reporting of randomization in abstracts; it is more likely to be reported in recent studies (P = 0.0094). No time trends are detected in the reporting of double-blind status (P = 0.1087) and adverse events (P = 0.6084). The reporting of adverse events in the abstract and the reporting of results specified by crossover period in the full texts of journal publications on crossover pain trials should be improved. Copyright © 2015 Elsevier Inc. All rights reserved.

Computational Ion Optics Design Evaluations

NASA Technical Reports Server (NTRS)

Malone, Shane P.; Soulas, George C.

2004-01-01

Ion optics computational models are invaluable tools in the design of ion optics systems. In this study a new computational model developed by an outside vendor for use at the NASA Glenn Research Center (GRC) is presented. This computational model is a gun code that has been modified to model the plasma sheaths both upstream and downstream of the ion optics. The model handles multiple species (e.g. singly and doubly-charged ions) and includes a charge-exchange model to support erosion estimations. The model uses commercially developed solid design and meshing software to allow high flexibility in ion optics geometric configurations. The results from this computational model are applied to the NEXT project to investigate the effects of crossover impingement erosion seen during the 2000-hour wear test.

A note on sample size calculation for mean comparisons based on noncentral t-statistics.

PubMed

Chow, Shein-Chung; Shao, Jun; Wang, Hansheng

2002-11-01

One-sample and two-sample t-tests are commonly used in analyzing data from clinical trials in comparing mean responses from two drug products. During the planning stage of a clinical study, a crucial step is the sample size calculation, i.e., the determination of the number of subjects (patients) needed to achieve a desired power (e.g., 80%) for detecting a clinically meaningful difference in the mean drug responses. Based on noncentral t-distributions, we derive some sample size calculation formulas for testing equality, testing therapeutic noninferiority/superiority, and testing therapeutic equivalence, under the popular one-sample design, two-sample parallel design, and two-sample crossover design. Useful tables are constructed and some examples are given for illustration.

Spin state switching in iron coordination compounds

PubMed Central

Gaspar, Ana B; Garcia, Yann

2013-01-01

Summary The article deals with coordination compounds of iron(II) that may exhibit thermally induced spin transition, known as spin crossover, depending on the nature of the coordinating ligand sphere. Spin transition in such compounds also occurs under pressure and irradiation with light. The spin states involved have different magnetic and optical properties suitable for their detection and characterization. Spin crossover compounds, though known for more than eight decades, have become most attractive in recent years and are extensively studied by chemists and physicists. The switching properties make such materials potential candidates for practical applications in thermal and pressure sensors as well as optical devices. The article begins with a brief description of the principle of molecular spin state switching using simple concepts of ligand field theory. Conditions to be fulfilled in order to observe spin crossover will be explained and general remarks regarding the chemical nature that is important for the occurrence of spin crossover will be made. A subsequent section describes the molecular consequences of spin crossover and the variety of physical techniques usually applied for their characterization. The effects of light irradiation (LIESST) and application of pressure are subjects of two separate sections. The major part of this account concentrates on selected spin crossover compounds of iron(II), with particular emphasis on the chemical and physical influences on the spin crossover behavior. The vast variety of compounds exhibiting this fascinating switching phenomenon encompasses mono-, oligo- and polynuclear iron(II) complexes and cages, polymeric 1D, 2D and 3D systems, nanomaterials, and polyfunctional materials that combine spin crossover with another physical or chemical property. PMID:23504535

Comparison between self-formulation and compounded-formulation dexamethasone mouth rinse for oral lichen planus: a pilot, randomized, cross-over trial.

PubMed

Hambly, Jessica L; Haywood, Alison; Hattingh, Laetitia; Nair, Raj G

2017-08-01

There is a lack of appropriate, commercially-available topical corticosteroid formulations for use in oral lichen planus (OLP) and oral lichenoid reaction. Current therapy includes crushing a dexamethasone tablet and mixing it with water for use as a mouth rinse. This formulation is unpleasant esthetically and to use in the mouth, as it is a bitter and gritty suspension, resulting in poor compliance. Thus, the present study was designed to formulate and pilot an effective, esthetically-pleasing formulation. A single-blinded, cross-over trial was designed with two treatment arms. Patients were monitored for 7 weeks. Quantitative and qualitative data was assessed using VAS, numeric pain scales, the Treatment Satisfaction Questionnaire for Medication-9, and thematic analysis to determine primary patient-reported outcomes, including satisfaction, compliance, quality of life, and symptom relief. Nine patients completed the pilot trial. Data analysis revealed the new compounded formulation to be superior to existing therapy due to its convenience, positive contribution to compliance, patient-perceived faster onset of action, and improved symptom relief. Topical dexamethasone is useful in the treatment of OLP. When carefully formulated into a compounded mouth rinse, it improves patient outcomes. © 2016 John Wiley & Sons Australia, Ltd.

Local and sex-specific biases in crossover vs. noncrossover outcomes at meiotic recombination hot spots in mice.

PubMed

de Boer, Esther; Jasin, Maria; Keeney, Scott

2015-08-15

Meiotic recombination initiated by programmed double-strand breaks (DSBs) yields two types of interhomolog recombination products, crossovers and noncrossovers, but what determines whether a DSB will yield a crossover or noncrossover is not understood. In this study, we analyzed the influence of sex and chromosomal location on mammalian recombination outcomes by constructing fine-scale recombination maps in both males and females at two mouse hot spots located in different regions of the same chromosome. These include the most comprehensive maps of recombination hot spots in oocytes to date. One hot spot, located centrally on chromosome 1, behaved similarly in male and female meiosis: Crossovers and noncrossovers formed at comparable levels and ratios in both sexes. In contrast, at a distal hot spot, crossovers were recovered only in males even though noncrossovers were obtained at similar frequencies in both sexes. These findings reveal an example of extreme sex-specific bias in recombination outcome. We further found that estimates of relative DSB levels are surprisingly poor predictors of relative crossover frequencies between hot spots in males. Our results demonstrate that the outcome of mammalian meiotic recombination can be biased, that this bias can vary depending on location and cellular context, and that DSB frequency is not the only determinant of crossover frequency. © 2015 de Boer et al.; Published by Cold Spring Harbor Laboratory Press.

The effect of secondary inorganic aerosols, soot and the geographical origin of air mass on acute myocardial infarction hospitalisations in Gothenburg, Sweden during 1985–2010: a case-crossover study

PubMed Central

2014-01-01

Background The relative importance of different sources of air pollution for cardiovascular disease is unclear. The aims were to compare the associations between acute myocardial infarction (AMI) hospitalisations in Gothenburg, Sweden and 1) the long-range transported (LRT) particle fraction, 2) the remaining particle fraction, 3) geographical air mass origin, and 4) influence of local dispersion during 1985–2010. Methods A case-crossover design was applied using lag0 (the exposure the same day as hospitalisation), lag1 (exposure one day prior hospitalisation) and 2-day cumulative average exposure (CA2) (mean of lag0 and lag1). The LRT fractions included PMion (sum of sulphate, nitrate and ammonium) and soot measured at a rural site. The difference between urban PM10 (particulate matter with an aerodynamic diameter smaller than 10 μm) and rural PMion was a proxy for locally generated PM10 (PMrest). The daily geographical origin of air mass was estimated as well as days with limited or effective local dispersion. The entire year was considered, as well as warm and cold periods, and different time periods. Results In total 28 215 AMI hospitalisations occurred during 26 years. PM10, PMion, PMrest and soot did not influence AMI for the entire year. In the cold period, the association was somewhat stronger for PMrest than for urban PM10; the strongest associations were observed during 1990–2000 between AMI and CA2 of PMrest (6.6% per inter-quartile range (IQR), 95% confidence interval 2.1 to 11.4%) and PM10 (4.1%, 95% CI 0.2% − 8.2%). Regarding the geographical air mass origins there were few associations. Days with limited local dispersion showed an association with AMI in the cold period of 2001–2010 (6.7%, 95% CI 0.0% − 13.0%). Conclusions In the cold period, locally generated PM and days with limited local dispersion affected AMI hospitalisations, indicating importance of local emissions from e.g. traffic. PMID:25069830

Hyperbaric Oxygen Therapy Can Improve Post Concussion Syndrome Years after Mild Traumatic Brain Injury - Randomized Prospective Trial

PubMed Central

Fishlev, Gregori; Bechor, Yair; Volkov, Olga; Bergan, Jacob; Friedman, Mony; Hoofien, Dan; Shlamkovitch, Nathan; Ben-Jacob, Eshel; Efrati, Shai

2013-01-01

Background Traumatic brain injury (TBI) is the leading cause of death and disability in the US. Approximately 70-90% of the TBI cases are classified as mild, and up to 25% of them will not recover and suffer chronic neurocognitive impairments. The main pathology in these cases involves diffuse brain injuries, which are hard to detect by anatomical imaging yet noticeable in metabolic imaging. The current study tested the effectiveness of Hyperbaric Oxygen Therapy (HBOT) in improving brain function and quality of life in mTBI patients suffering chronic neurocognitive impairments. Methods and Findings The trial population included 56 mTBI patients 1–5 years after injury with prolonged post-concussion syndrome (PCS). The HBOT effect was evaluated by means of prospective, randomized, crossover controlled trial: the patients were randomly assigned to treated or crossover groups. Patients in the treated group were evaluated at baseline and following 40 HBOT sessions; patients in the crossover group were evaluated three times: at baseline, following a 2-month control period of no treatment, and following subsequent 2-months of 40 HBOT sessions. The HBOT protocol included 40 treatment sessions (5 days/week), 60 minutes each, with 100% oxygen at 1.5 ATA. “Mindstreams” was used for cognitive evaluations, quality of life (QOL) was evaluated by the EQ-5D, and changes in brain activity were assessed by SPECT imaging. Significant improvements were demonstrated in cognitive function and QOL in both groups following HBOT but no significant improvement was observed following the control period. SPECT imaging revealed elevated brain activity in good agreement with the cognitive improvements. Conclusions HBOT can induce neuroplasticity leading to repair of chronically impaired brain functions and improved quality of life in mTBI patients with prolonged PCS at late chronic stage. Trial Registration ClinicalTrials.gov NCT00715052 PMID:24260334

Crossover physics in the nonequilibrium dynamics of quenched quantum impurity systems.

PubMed

Vasseur, Romain; Trinh, Kien; Haas, Stephan; Saleur, Hubert

2013-06-14

A general framework is proposed to tackle analytically local quantum quenches in integrable impurity systems, combining a mapping onto a boundary problem with the form factor approach to boundary-condition-changing operators introduced by Lesage and Saleur [Phys. Rev. Lett. 80, 4370 (1998)]. We discuss how to compute exactly the following two central quantities of interest: the Loschmidt echo and the distribution of the work done during the quantum quench. Our results display an interesting crossover physics characterized by the energy scale T(b) of the impurity corresponding to the Kondo temperature. We discuss in detail the noninteracting case as a paradigm and benchmark for more complicated integrable impurity models and check our results using numerical methods.

Variation and Evolution of the Meiotic Requirement for Crossing Over in Mammals.

PubMed

Dumont, Beth L

2017-01-01

The segregation of homologous chromosomes at the first meiotic division is dependent on the presence of at least one well-positioned crossover per chromosome. In some mammalian species, however, the genomic distribution of crossovers is consistent with a more stringent baseline requirement of one crossover per chromosome arm. Given that the meiotic requirement for crossing over defines the minimum frequency of recombination necessary for the production of viable gametes, determining the chromosomal scale of this constraint is essential for defining crossover profiles predisposed to aneuploidy and understanding the parameters that shape patterns of recombination rate evolution across species. Here, I use cytogenetic methods for in situ imaging of crossovers in karyotypically diverse house mice (Mus musculus domesticus) and voles (genus Microtus) to test how chromosome number and configuration constrain the distribution of crossovers in a genome. I show that the global distribution of crossovers in house mice is thresholded by a minimum of one crossover per chromosome arm, whereas the crossover landscape in voles is defined by a more relaxed requirement of one crossover per chromosome. I extend these findings in an evolutionary metaanalysis of published recombination and karyotype data for 112 mammalian species and demonstrate that the physical scale of the genomic crossover distribution has undergone multiple independent shifts from one crossover per chromosome arm to one per chromosome during mammalian evolution. Together, these results indicate that the chromosomal scale constraint on crossover rates is itself a trait that evolves among species, a finding that casts light on an important source of crossover rate variation in mammals. Copyright © 2017 by the Genetics Society of America.

Associations between ozone, PM2.5, and four pollen types on emergency department pediatric asthma events during the warm season in New Jersey: a case-crossover study.

PubMed

Gleason, Jessie A; Bielory, Leonard; Fagliano, Jerald A

2014-07-01

Asthma is one of the most common chronic diseases among school-aged children in the United States. Environmental respiratory irritants exacerbate asthma among children. Understanding the impact of a variety of known and biologically plausible environmental irritants and triggers among children in New Jersey - ozone, fine particulate matter (PM2.5), tree pollen, weed pollen, grass pollen and ragweed - would allow for informed public health interventions. Time-stratified case-crossover design was used to study the transient impact of ozone, PM2.5 and pollen on the acute onset of pediatric asthma. Daily emergency department visits were obtained for children aged 3-17 years with a primary diagnosis of asthma during the warm season (April through September), 2004-2007 (inclusive). Bi-directional control sampling was used to select two control periods for each case for a total of 65,562 inclusion days. Since the period of exposure prior to emergency department visit may be the most clinically relevant, lag exposures were investigated (same day (lag0), 1, 2, 3, 4, and 5 as well as 3-day and 5-day moving averages). Multivariable conditional logistic regression controlling for holiday, school-in-session indicator, and 3-day moving average for temperature and relative humidity was used to examine the associations. Odds ratios are based on interquartile range (IQR) increases or 10 unit increases when IQR ranges were narrow. Single-pollutant models as well as multipollutant models were examined. Stratification on gender, race, ethnicity and socioeconomic status was explored. The associations with ozone and PM2.5 were strongest on the same day (lag0) of the emergency department visit (RR IQR=1.05, 95% CI 1.04-1.06) and (RR IQR=1.03, 95% CI 1.02-1.04), respectively, with a decreasing lag effect. Tree and weed pollen were associated with pediatric ED visits; the largest magnitudes of association was with the 5-day average (RR IQR=1.23, 95% CI 1.21-1.25) and (RR 10=1.13, 95% CI 1.12-1.14), respectively. Grass pollen was only minimally associated with the outcome while ragweed had a negative association. The ambient air pollutant ozone is associated with increases in pediatric emergency department asthma visits during the warm weather season. The different pollen types showed different associations with the outcome. High levels of tree pollen appear to be an important risk factor in asthma exacerbations. Copyright © 2014 Elsevier Inc. All rights reserved.

No evidence for differential dose effects of hydrocortisone on intrusive memories in female patients with complex post-traumatic stress disorder--a randomized, double-blind, placebo-controlled, crossover study.

PubMed

Ludäscher, Petra; Schmahl, Christian; Feldmann, Robert E; Kleindienst, Nikolaus; Schneider, Miriam; Bohus, Martin

2015-10-01

Post-traumatic stress disorder is characterized by intrusive traumatic memories. Presently, a controversial debate is ongoing regarding whether reduced cortisol secretion in post-traumatic stress disorder promotes an automatic retrieval of trauma-associated memories. Hence, a pharmacological elevation of cortisol was proposed to decrease post-traumatic stress disorder symptoms, particularly intrusions. The present study investigated the impact of two different doses of hydrocortisone on automatic memory retrieval using a randomized, double-blind, placebo-controlled, crossover study in 30 inpatients with post-traumatic stress disorder. All participants were female and received various psychotropic medications. They were randomly assigned to one of two groups within a crossover design: they received either 1 week placebo followed by 1 week hydrocortisone 10/d, followed by 1 week placebo, followed by hydrocortisone 30 mg/d (15 participants) or 1 week hydrocortisone 30 mg/d, followed by 1 week placebo, followed by 1 week hydrocortisone 10 mg/d, followed by 1 week placebo (15 participants). The outcome measures were the frequency and the intensity of intrusions, the overall symptomatology of post-traumatic stress disorder and the general psychopathology. We did not find any differences in the frequency and the intensity of post-traumatic stress disorder-related intrusions between the 10 mg hydrocortisone, the 30 mg hydrocortisone and the placebo condition. All effect sizes for the hydrocortisone condition vs. placebo were very small. Additionally, the overall symptomatology of post-traumatic stress disorder and the general psychopathology did not differ between the hydrocortisone therapies and placebo. Our results do not show any effect of the hydrocortisone administration on intrusions in complex post-traumatic stress disorder. © The Author(s) 2015.

A randomized, double-blind, crossover, placebo-controlled comparative clinical trial of arginine aspartate plus adenosine monophosphate for the intermittent treatment of male erectile dysfunction.

PubMed

Neuzillet, Y; Hupertan, V; Cour, F; Botto, H; Lebret, T

2013-03-01

Efficacy and safety of l-arginine aspartate 8 g combined with 200 mg of adenosine monophosphate (AA) with placebo (PL) alone for intermittent treatment of mild-to-moderate erectile dysfunction (ED) were compared. The study design was a double-blind, PL-controlled, two-way crossover randomized clinical trial with 26 patients. Efficacy was assessed by International Index of Erectile Function (IIEF) and two additional validated questionnaires [the Erection Hardness Score (EHS) and the Erectile Dysfunction Inventory of Treatment Satisfaction (EDITS). During each crossover period, separated by a 2-week wash-out period, drugs were administered orally, 1-2 h before sexual intercourse. Primary endpoint was a change in the IIEF. Secondary endpoints were patient and investigator assessments of treatment success. Investigators' and patients' assessment of efficacy was significantly improved by the combination vs. PL (p = 0.01 and p = 0.04 respectively]. EHS and EDITS questionnaires were both improved by the combination (p = 0.015 and p = 0.017 respectively). There was no significant difference in terms of tolerance between AA and PL or severe adverse events. ED patients demonstrated significant improvements in all IIEF domains with the exception of the Sexual Desire and Orgasmic Domains when treated with AA compared with PL. This pilot phase II study showed that the on-demand oral administration at a high dosage of l-arginine aspartate-adenosine monophosphate combination may be effective in patients with mild-to-moderate ED, is very well tolerated and could be tested as a safe first-line therapy in a larger size phase III study. © 2012 American Society of Andrology and European Academy of Andrology.

Weather conditions may worsen symptoms in rheumatoid arthritis patients: the possible effect of temperature.

PubMed

Abasolo, Lydia; Tobías, Aurelio; Leon, Leticia; Carmona, Loreto; Fernandez-Rueda, Jose Luis; Rodriguez, Ana Belen; Fernandez-Gutierrez, Benjamin; Jover, Juan Angel

2013-01-01

Patients with rheumatoid arthritis (RA) complain that weather conditions aggravate their symptoms. We investigated the short-term effects of weather conditions on worsening of RA and determined possible seasonal fluctuations. We conducted a case-crossover study in Madrid, Spain. Daily cases of RA flares were collected from the emergency room of a tertiary level hospital between 2004 and 2007. 245 RA patients who visited the emergency room 306 times due to RA related complaints as the main diagnostic reason were included in the study. Patients from 50 to 65 years old were 16% more likely to present a flare with lower mean temperatures. Our results support the belief that weather influences rheumatic pain in middle aged patients. Copyright © 2012 Elsevier España, S.L. All rights reserved.

Paresthesia-Free High-Density Spinal Cord Stimulation for Postlaminectomy Syndrome in a Prescreened Population: A Prospective Case Series.

PubMed

Sweet, Jennifer; Badjatiya, Anish; Tan, Daniel; Miller, Jonathan

2016-04-01

Spinal cord stimulation (SCS) traditionally is thought to require paresthesia, but there is evidence that paresthesia-free stimulation using high-density (HD) parameters might also be effective. The purpose of this study is to evaluate relative effectiveness of conventional, subthreshold HD, and sham stimulation on pain intensity and quality of life. Fifteen patients with response to conventional stimulation (60 Hz/350 μsec) were screened with a one-week trial of subthreshold HD (1200 Hz/200 μsec/amplitude 90% paresthesia threshold) and enrolled if there was at least 50% reduction on visual analog scale (VAS) for pain. Subjects were randomized into two groups and treated with four two-week periods of conventional, subthreshold HD, and sham stimulation in a randomized crossover design. Four of 15 patients responded to subthreshold HD stimulation. Mean VAS during conventional, subthreshold HD, and sham stimulation was 5.32 ± 0.63, 2.29 ± 0.41, and 6.31 ± 1.22, respectively. There was a significant difference in pain scores during the blinded crossover study of subthreshold HD vs. sham stimulation (p < 0.05, Student's t-test). Post hoc analysis revealed that subjects reported significantly greater attention to pain during conventional stimulation compared with subthreshold HD stimulation (p < 0.05, Student's t-test). All subjects reported a positive impression of change for subthreshold HD stimulation compared with conventional stimulation, and there was a trend toward greater likelihood for response to subthreshold HD stimulation in comparison with sham stimulation (p = 0.07, Fisher's exact test). At the end of the trial, all subjects elected to continue to receive subthreshold HD stimulation rather than conventional stimulation. Paresthesia are not necessary for pain relief using commercially available SCS devices, and may actually increase attention to pain. Subthreshold HD SCS represents a viable alternative to conventional stimulation among patients who are confirmed to have a clinical response to it. © 2015 International Neuromodulation Society.

Association between ambient air pollution and hospitalization for ischemic and hemorrhagic stroke in China: A multicity case-crossover study.

PubMed

Liu, Hui; Tian, Yaohua; Xu, Yan; Huang, Zhe; Huang, Chao; Hu, Yonghua; Zhang, Jun

2017-11-01

There is growing interest in the association between ambient air pollution and stroke, but few studies have investigated the association in developing countries. The primary objective of this study was to examine the association between levels of ambient air pollutants and hospital admission for stroke in China. A time-stratified case-crossover analysis was conducted between 2014 and 2015 in 14 large Chinese cities among 200,958 ischemic stroke and 41,746 hemorrhagic stroke hospitalizations. We used conditional logistic regression to estimate the percentage changes in stroke admissions in relation to interquartile range increases in air pollutants. Air pollution was positively associated with ischemic stroke. A difference of an interquartile range of the 6-day average for particulate matter less than 10 μm in aerodynamic diameter, sulfur dioxide, nitrogen dioxide, carbon monoxide, and ozone corresponded to 0.7% (95% CI: 0%, 1.4%), 1.6% (95% CI: 1.0%, 2.3%), 2.6% (95% CI: 1.8%, 3.5%), 0.5% (95% CI: -0.2%, 1.1%), and 1.3% (95% CI: 0.3%, 2.3%) increases in ischemic stroke admissions, respectively. For hemorrhagic stroke, we observed the only significant association in relation to nitrogen dioxide on the current day (percentage change: 1.6%; 95% CI: 0.3%, 2.9%). Our findings contribute to the limited scientific literature concerning the effect of ambient air pollution on stroke in developing countries. Our findings may have significant public health implications for primary prevention of stroke in China. Copyright © 2017 Elsevier Ltd. All rights reserved.

Relative bioavailability of methadone hydrochloride administered in chewing gum and tablets.

PubMed

Christrup, L L; Angelo, H R; Bonde, J; Kristensen, F; Rasmussen, S N

1990-01-01

Methadone administered in chewing gum in doses of 16.7-22.6 mg to seven patients in a study using an open balanced cross-over design, was compared with 20 mg of methadone given perorally as tablets. There was no significant difference in the AUC/D obtained after administration of chewing gum and tablets (p greater than 0.05). It is concluded that the chewing gum formulation should be considered for further testing with respect to suppression of abstinence syndrome in narcotic addicts.

Acute triggers of myocardial infarction: A case-crossover study.

PubMed

Ghiasmand, Maryam; Moghadamnia, Mohammad Taghi; Pourshaikhian, Majid; Kazemnejad Lili, Ehsan

2017-12-01

Acute myocardial infarction (AMI) is one of the most preventable non-communicable diseases in human. Identifying triggers of myocardial infarction (MI) and prevention ways of exposure-induced complications can reduce morbidity and mortality in people at risk. The aim of this study was to identify the emotional, environmental, physical and chemical dimensions of acute triggers in patients with AMI. This case-crossover study was conducted on 269 patients with AMI, hospitalized at two remedial centers in Rasht in 2015. The study samples were selected by convenient sampling method. Data were collected using researcher-made questionnaire through interviews. Hazard and control periods for each trigger and its effects on the development of MI were studied. The collected data were analyzed using descriptive and analytical statistical methods, Cochran test, and generalized estimating equation (GEE) model with logistics function default in SPSS version 21, and p  < 0.05 was considered statistically significant. The results showed that quarrel ( P  = 0.008, OR = 2.01) and hearing the sudden news ( P  = 0.001, OR = 2.19) were the most common emotional triggers. Respiratory infections ( P  = 0.0001, OR = 6.78) and exposure to hot or cold weather ( P  = 0.005, OR = 2.19) were the most frequent environmental triggers. Doing heavy activities ( P  = 0.005, OR = 1.66) and sexual activities ( P  = 0.003, OR = 2.36) were among the most common physical triggers. High-fat foods consumption and overeating ( P  = 0.0001, OR = 3.79) were the most frequent chemical triggers of AMI. It seems that given the importance of the triggers in the incidence of AMI, planning is necessary to train vulnerable individuals to reduce exposure to triggers.

The association between air pollution and mortality in Thailand

PubMed Central

Guo, Yuming; Li, Shanshan; Tawatsupa, Benjawan; Punnasiri, Kornwipa; Jaakkola, Jouni J. K.; Williams, Gail

2014-01-01

Bayesian statistical inference with a case-crossover design was used to examine the effects of air pollutants {Particulate matter <10 μm in aerodynamic diameter (PM10), sulphur dioxide (SO2), and ozone (O3)} on mortality. We found that all air pollutants had significant short-term impacts on non-accidental mortality. An increase of 10 μg/m3 in PM10, 10 ppb in O3, 1 ppb in SO2 were associated with a 0.40% (95% posterior interval (PI): 0.22, 0.59%), 0.78% (95% PI: 0.20, 1.35%) and 0.34% (95% PI: 0.17, 0.50%) increase of non-accidental mortality, respectively. O3 air pollution is significantly associated with cardiovascular mortality, while PM10 is significantly related to respiratory mortality. In general, the effects of all pollutants on all mortality types were higher in summer and winter than those in the rainy season. This study highlights the effects of exposure to air pollution on mortality risks in Thailand. Our findings support the Thailand government in aiming to reduce high levels of air pollution. PMID:24981315

The association between air pollution and mortality in Thailand.

PubMed

Guo, Yuming; Li, Shanshan; Tawatsupa, Benjawan; Punnasiri, Kornwipa; Jaakkola, Jouni J K; Williams, Gail

2014-07-01

Bayesian statistical inference with a case-crossover design was used to examine the effects of air pollutants {Particulate matter <10 μm in aerodynamic diameter (PM10), sulphur dioxide (SO₂), and ozone (O₃)} on mortality. We found that all air pollutants had significant short-term impacts on non-accidental mortality. An increase of 10 μg/m(3) in PM10, 10 ppb in O₃, 1 ppb in SO₂ were associated with a 0.40% (95% posterior interval (PI): 0.22, 0.59%), 0.78% (95% PI: 0.20, 1.35%) and 0.34% (95% PI: 0.17, 0.50%) increase of non-accidental mortality, respectively. O₃ air pollution is significantly associated with cardiovascular mortality, while PM10 is significantly related to respiratory mortality. In general, the effects of all pollutants on all mortality types were higher in summer and winter than those in the rainy season. This study highlights the effects of exposure to air pollution on mortality risks in Thailand. Our findings support the Thailand government in aiming to reduce high levels of air pollution.

Design and optimization of a single stage centrifugal compressor for a solar dish-Brayton system

NASA Astrophysics Data System (ADS)

Wang, Yongsheng; Wang, Kai; Tong, Zhiting; Lin, Feng; Nie, Chaoqun; Engeda, Abraham

2013-10-01

According to the requirements of a solar dish-Brayton system, a centrifugal compressor stage with a minimum total pressure ratio of 5, an adiabatic efficiency above 75% and a surge margin more than 12% needs to be designed. A single stage, which consists of impeller, radial vaned diffuser, 90° crossover and two rows of axial stators, was chosen to satisfy this system. To achieve the stage performance, an impeller with a 6:1 total pressure ratio and an adiabatic efficiency of 90% was designed and its preliminary geometry came from an in-house one-dimensional program. Radial vaned diffuser was applied downstream of the impeller. Two rows of axial stators after 90° crossover were added to guide the flow into axial direction. Since jet-wake flow, shockwave and boundary layer separation coexisted in the impeller-diffuser region, optimization on the radius ratio of radial diffuser vane inlet to impeller exit, diffuser vane inlet blade angle and number of diffuser vanes was carried out at design point. Finally, an optimized centrifugal compressor stage fulfilled the high expectations and presented proper performance. Numerical simulation showed that at design point the stage adiabatic efficiency was 79.93% and the total pressure ratio was 5.6. The surge margin was 15%. The performance map including 80%, 90% and 100% design speed was also presented.

Supplementation with beta-hydroxy-beta-methylbutyrate (HMB) and alpha-ketoisocaproic acid (KIC) reduces signs and symptoms of exercise-induced muscle damage in man.

PubMed

van Someren, Ken A; Edwards, Adam J; Howatson, Glyn

2005-08-01

This study examined the effects of beta-hydroxyl-beta-methylbutyrate (HMB) and alpha-ketoisocaproic acid (KIC) supplementation on signs and symptoms of exercise-induced muscle damage following a single bout of eccentrically biased resistance exercise. Six non-resistance trained male subjects performed an exercise protocol designed to induce muscle damage on two separate occasions, performed on the dominant or non-dominant arm in a counter-balanced crossover design. Subjects were assigned to an HMB/KIC (3 g HMB and 0.3 g alpha-ketoisocaproic acid, daily) or placebo treatment for 14 d prior to exercise in the counter-balanced crossover design. One repetition maximum (1RM), plasma creatine kinase activity (CK), delayed onset muscle soreness (DOMS), limb girth, and range of motion (ROM) were determined pre-exercise, at 1h, 24 h, 48 h, and 72 h post-exercise. DOMS and the percentage changes in 1RM, limb girth, and ROM all changed over the 72 h period (P < 0.05). HMB//IC supplementation attenuated the CK response, the percentage decrement in 1RM, and the percentage increase in limb girth (P < 0.05). In addition, DOMS was reduced at 24 h post-exercise (P < 0.05) in the HMB/KIC treatment. In conclusion, 14 d of HMB and KIC supplementation reduced signs and symptoms of exercise-induced muscle damage in non-resistance trained males following a single bout of eccentrically biased resistance exercise.

A case-crossover analyses of fine particulate matter and out-of-hospital sudden unexpected death

EPA Science Inventory

Out-of-hospital sudden unexpected deaths (OHSUD) are natural deaths that occur without obvious underlying causes and account for nearly 1 in 6 deaths in the United States. Ambient air pollution is known to be causally related to overall mortality, therefore, we hypothesized that ...

Flooding and intestinal illness due to Clostridium difficile infection: a case-crossover analysis of Massachusetts data, 2003-2007

EPA Science Inventory

Background. Climate change has contributed to a rise in extreme weather events, including heavier rainfalls. Floods can cause water bodies to overflow, damage water treatment and drinking water infrastructure, overwhelm sewage treatment facilities, and result in discharges of un...

A CASE-CROSSOVER ANALYSIS OF PARTICULATE MATTER AIR POLLUTION AND OUT-OF-HOSPITAL PRIMARY CARDIAC ARREST. (R827355C001)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

REFERENT SELECTION IN CASE-CROSSOVER ANALYSES OF ACUTE HEALTH EFFECTS OF AIR POLLUTION. (R827355C001)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

Virtual walks in spin space: A study in a family of two-parameter models

NASA Astrophysics Data System (ADS)

Mullick, Pratik; Sen, Parongama

2018-05-01

We investigate the dynamics of classical spins mapped as walkers in a virtual "spin" space using a generalized two-parameter family of spin models characterized by parameters y and z [de Oliveira et al., J. Phys. A 26, 2317 (1993), 10.1088/0305-4470/26/10/006]. The behavior of S (x ,t ) , the probability that the walker is at position x at time t , is studied in detail. In general S (x ,t ) ˜t-αf (x /tα) with α ≃1 or 0.5 at large times depending on the parameters. In particular, S (x ,t ) for the point y =1 ,z =0.5 corresponding to the Voter model shows a crossover in time; associated with this crossover, two timescales can be defined which vary with the system size L as L2logL . We also show that as the Voter model point is approached from the disordered regions along different directions, the width of the Gaussian distribution S (x ,t ) diverges in a power law manner with different exponents. For the majority Voter case, the results indicate that the the virtual walk can detect the phase transition perhaps more efficiently compared to other nonequilibrium methods.

Comparative evaluation of stress levels before, during, and after periodontal surgical procedures with and without nitrous oxide-oxygen inhalation sedation

PubMed Central

Sandhu, Gurkirat; Khinda, Paramjit Kaur; Gill, Amarjit Singh; Singh Khinda, Vineet Inder; Baghi, Kamal; Chahal, Gurparkash Singh

2017-01-01

Context: Periodontal surgical procedures produce varying degree of stress in all patients. Nitrous oxide-oxygen inhalation sedation is very effective for adult patients with mild-to-moderate anxiety due to dental procedures and needle phobia. Aim: The present study was designed to perform periodontal surgical procedures under nitrous oxide-oxygen inhalation sedation and assess whether this technique actually reduces stress physiologically, in comparison to local anesthesia alone (LA) during lengthy periodontal surgical procedures. Settings and Design: This was a randomized, split-mouth, cross-over study. Materials and Methods: A total of 16 patients were selected for this randomized, split-mouth, cross-over study. One surgical session (SS) was performed under local anesthesia aided by nitrous oxide-oxygen inhalation sedation, and the other SS was performed on the contralateral quadrant under LA. For each session, blood samples to measure and evaluate serum cortisol levels were obtained, and vital parameters including blood pressure, heart rate, respiratory rate, and arterial blood oxygen saturation were monitored before, during, and after periodontal surgical procedures. Statistical Analysis Used: Paired t-test and repeated measure ANOVA. Results: The findings of the present study revealed a statistically significant decrease in serum cortisol levels, blood pressure and pulse rate and a statistically significant increase in respiratory rate and arterial blood oxygen saturation during periodontal surgical procedures under nitrous oxide inhalation sedation. Conclusion: Nitrous oxide-oxygen inhalation sedation for periodontal surgical procedures is capable of reducing stress physiologically, in comparison to LA during lengthy periodontal surgical procedures. PMID:29386796

Cardio-autonomic control and wellbeing due to oscillating color light exposure.

PubMed

Grote, Vincent; Kelz, Christina; Goswami, Nandu; Stossier, Harald; Tafeit, Erwin; Moser, Maximilian

2013-04-10

We investigated the cardio-autonomic and psychological effects of colored light cycling with the wavelength of ultradian rhythms. In two consecutive experiments, an explorative, longitudinal test followed by a randomized crossover design, 20 healthy subjects each were exposed to oscillating red, green and blue light. Heart rate, heart rate variability (HRV) and subjective wellbeing were measured. Significant effects of the oscillating color light exposure were observed for heart rate and cardio-autonomic control rhythms, derived from HRV (p≤.001). These effects on HRV were replicated in the second experiment in comparison to a similar white light exposure protocol (p≤.05). Vigilance showed improvement over the two weeks (p≤.001) in the longitudinal study. External color light cycling at the wavelength of blood pressure oscillations appears to amplify the endogenous autonomic oscillations. This leads to an optimization of cardio-autonomic control; an effect that was reflected shortly after the onset of the light exposure sessions by the increase of heart rate variability. From the results, we conclude that it takes repeated light exposure session to foster the positive effects on the psychological aspects, as we observed an increase of subjectively perceived mood only in the longitudinal study, not for the crossover design study. The results of our study imply some possible health effects of a color light exposure that is adjusted to 10 s and 1 min oscillations of humans' ultradian rhythms. These novel results show possible applications of oscillating visual inputs to the activation of processes connected to physiological regulation. Copyright © 2013 Elsevier Inc. All rights reserved.

The effects of physical therapy with neuromuscular electrical stimulation in patients with septic shock: Study protocol for a randomized cross-over design.

PubMed

Lago, Alessandra Fabiane; de Oliveira, Anamaria Siriani; de Souza, Hugo Celso Dutra; da Silva, João Santana; Basile-Filho, Anibal; Gastaldi, Ada Clarice

2018-02-01

Septic shock is a potentially fatal organ dysfunction caused by an imbalance of the host response to infection. The changes in microcirculation during sepsis can be explained by the alterations in the endothelial barrier function. Endothelial progenitor cells (EPCs) are a potential recovery index of endothelial function and it an increase in response to neuromuscular electrical stimulation (NMES) was demonstrated. Therefore, the objective of this study is to investigate the effects of NMES in patients with septic shock. It is a study protocol for a randomized cross-over design in an intensive care unit of a tertiary University hospital. Thirty-one patients aged 18 to 65 years. The study will be divided in 2 phases: the phase one will be held in the first 72 hours of septic shock and the phase two after 3 days of first assessment. Patients will be randomly selected to the intervention protocol (decubitus position with the limbs raised and NMES) and control protocol (decubitus position with the limbs raised without NMES). After this procedure, the patients will be allocated in group 1 (intervention and control protocol) or group 2 (control and intervention protocol) with a wash-out period of 4 to 6 hours between them. The main outcome is mobilization of EPCs. The secondary outcome is metabolic and hemodynamic data. A linear mixed model will be used for analysis of dependent variables and estimated values of the mean of the differences of each effect.

Atenolol versus pindolol: side-effects in hypertension.

PubMed

Foerster, E C; Greminger, P; Siegenthaler, W; Vetter, H; Vetter, W

1985-01-01

This randomized crossover out-patient study was designed to compare the antihypertensive effects of atenolol and pindolol. After a wash-out period of two weeks in pretreated cases, 107 patients with essential hypertension were given either atenolol 100 mg once-daily or pindolol 20 mg slow release (SR) once-daily. Both atenolol and pindolol lowered blood pressure over the 24 week period. The diastolic blood pressure reduction was significantly greater (p less than 0.01) with atenolol than with pindolol. Before beta-blocker therapy, many patients had already experienced side-effects such as fatigue, sleep disturbances and dreams. This probably relates to the high sensitivity of the analogue scale used to assess side-effects, and to the high incidence of such symptoms in untreated patients. As the study progressed there was a reduction in the frequency of fatigue (p less than 0.03) and dreams (p less than 0.05) in both groups, whereas sleep disturbances significantly increased under pindolol (p less than 0.05) but decreased under atenolol (p less than 0.05). The only important side-effect difference between the two beta-blockers was the higher incidence of sleep disturbances with pindolol which may be due to the higher lipophilicity of this beta-blocker.

A simple, fast and accurate in-situ method to measure the rate of transport of redox species through membranes for lithium batteries

NASA Astrophysics Data System (ADS)

Meddings, Nina; Owen, John R.; Garcia-Araez, Nuria

2017-10-01

Lithium ion conducting membranes are important to protect the lithium metal electrode and act as a barrier to crossover species such as polysulphides in Li-S systems, redox mediators in Li-O2 cells or dissolved cathode species or electrolyte oxidation products in high voltage Li-ion batteries. We present an in-situ method for measuring permeability of membranes to crossover redox species. The method employs a 'Swagelok' cell design equipped with a glassy carbon working electrode, in which redox species are placed initially in the counter electrode compartment only. Permeability through the membrane, which separates working and counter electrodes, is determined using a square wave voltammetry technique that allows the concentration of crossover redox species to be evaluated over time with very high precision. We test the method using a model and well-behaved electrochemical system to demonstrate its sensitivity, reproducibility and reliability relative to alternative approaches. This new method offers advantages in terms of small electrolyte volume, and simple, fast, quantitative and in-situ measurement.

Advantages of using voiced questionnaire and image capture application for data collection from a minority group in rural areas along the Thailand-Myanmar border.

PubMed

Monyarit, Siriporn; Pan-ngum, Wirichada; Lawpoolsri, Saranath; Yimsamran, Surapon; Pongnumkul, Suporn; Kaewkungwal, Jaranit; Singhasivanon, Pratap

2014-01-01

To compare the quality of data collection via electronic data capture (EDC) with voiced questionnaire (QNN) and data image capture features using a tablet versus standard paper-based QNN, to assess the user's perception of using the EDC tool, and to compare user satisfaction with the two methods. Randomised cross-over study. Study sites: This study was conducted in two villages along the Thailand-Myanmar border. This study included 30 community health volunteers (CHVs) and 120 Karen hill tribe villagers. Employing a cross-over study design, the CHVs were allocated randomly to two groups, in which they performed interviews in different sequences using EDC and QNN. Data discrepancies were found between the two data-collection methods, when data from the paper-based and image-capture methods were compared, and when conducting skip pattern questions. More than 90% of the CHVs perceived the EDC to be useful and easy to use. Both interviewers and interviewees were more satisfied with the EDC compared with QNN in terms of format, ease of use, and system speed. The EDC can effectively be used as an alternative method to paper-based QNNs for data collection. It produces more accurate data that can be considered evidence-based.

Elimination of active species crossover in a room temperature, neutral pH, aqueous flow battery using a ceramic NaSICON membrane

NASA Astrophysics Data System (ADS)

Allcorn, Eric; Nagasubramanian, Ganesan; Pratt, Harry D.; Spoerke, Erik; Ingersoll, David

2018-02-01

Flow batteries are an attractive technology for energy storage of grid-scale renewables. However, performance issues related to ion-exchange membrane (IEM) fouling and crossover of species have limited the success of flow batteries. In this work we propose the use of the solid-state sodium-ion conductor NaSICON as an IEM to fully eliminate active species crossover in room temperature, aqueous, neutral pH flow batteries. We measure the room temperature conductivity of NaSICON at 2.83-4.67 mS cm-1 and demonstrate stability of NaSICON in an aqueous electrolyte with conductivity values remaining near 2.5 mS cm-1 after 66 days of exposure. Charge and discharge of a full H-cell battery as well as symmetric cycling in a flow battery configuration using NaSICON as an IEM in both cases demonstrates the capability of the solid-state IEM. Extensive analysis of aged cells through electrochemical impedance spectroscopy (EIS) and UV-vis spectroscopy show no contaminant species having crossed over the NaSICON membrane after 83 days of exposure, yielding an upper limit to the permeability of NaSICON of 4 × 10-10 cm2 min-1. The demonstration of NaSICON as an IEM enables a wide new range of chemistries for application to flow batteries that would previously be impeded by species crossover and associated degradation.

Elimination of active species crossover in a room temperature, neutral pH, aqueous flow battery using a ceramic NaSICON membrane

DOE Office of Scientific and Technical Information (OSTI.GOV)

Allcorn, Eric; Nagasubramanian, Ganesan; Pratt, III, Harry D.

Flow batteries are an attractive technology for energy storage of grid-scale renewables. However, performance issues related to ion-exchange membrane (IEM) fouling and crossover of species have limited the success of flow batteries. In this work we propose the use of the solid-state sodium-ion conductor NaSICON as an IEM to fully eliminate active species crossover in room temperature, aqueous, neutral pH flow batteries. We measure the room temperature conductivity of NaSICON at 2.83–4.67 mS cm –1 and demonstrate stability of NaSICON in an aqueous electrolyte with conductivity values remaining near 2.5 mS cm –1 after 66 days of exposure. Charge andmore » discharge of a full H-cell battery as well as symmetric cycling in a flow battery configuration using NaSICON as an IEM in both cases demonstrates the capability of the solid-state IEM. Extensive analysis of aged cells through electrochemical impedance spectroscopy (EIS) and UV–vis spectroscopy show no contaminant species having crossed over the NaSICON membrane after 83 days of exposure, yielding an upper limit to the permeability of NaSICON of 4 × 10 –10 cm 2 min –1. As a result, the demonstration of NaSICON as an IEM enables a wide new range of chemistries for application to flow batteries that would previously be impeded by species crossover and associated degradation.« less

Elimination of active species crossover in a room temperature, neutral pH, aqueous flow battery using a ceramic NaSICON membrane

DOE PAGES

Allcorn, Eric; Nagasubramanian, Ganesan; Pratt, III, Harry D.; ...

2018-01-04

Flow batteries are an attractive technology for energy storage of grid-scale renewables. However, performance issues related to ion-exchange membrane (IEM) fouling and crossover of species have limited the success of flow batteries. In this work we propose the use of the solid-state sodium-ion conductor NaSICON as an IEM to fully eliminate active species crossover in room temperature, aqueous, neutral pH flow batteries. We measure the room temperature conductivity of NaSICON at 2.83–4.67 mS cm –1 and demonstrate stability of NaSICON in an aqueous electrolyte with conductivity values remaining near 2.5 mS cm –1 after 66 days of exposure. Charge andmore » discharge of a full H-cell battery as well as symmetric cycling in a flow battery configuration using NaSICON as an IEM in both cases demonstrates the capability of the solid-state IEM. Extensive analysis of aged cells through electrochemical impedance spectroscopy (EIS) and UV–vis spectroscopy show no contaminant species having crossed over the NaSICON membrane after 83 days of exposure, yielding an upper limit to the permeability of NaSICON of 4 × 10 –10 cm 2 min –1. As a result, the demonstration of NaSICON as an IEM enables a wide new range of chemistries for application to flow batteries that would previously be impeded by species crossover and associated degradation.« less

Acetic acid-guided biopsies in Barrett’s surveillance for neoplasia detection versus non-targeted biopsies (Seattle protocol): A feasibility study for a randomized tandem endoscopy trial. The ABBA study

PubMed Central

Chedgy, Fergus; Fogg, Carole; Kandiah, Kesavan; Barr, Hugh; Higgins, Bernard; McCord, Mimi; Dewey, Ann; De Caestecker, John; Gadeke, Lisa; Stokes, Clive; Poller, David; Longcroft-Wheaton, Gaius; Bhandari, Pradeep

2018-01-01

Background and study aims  Barrett’s esophagus is a potentially pre-cancerous condition, affecting 375,000 people in the UK. Patients receive a 2-yearly endoscopy to detect cancerous changes, as early detection and treatment results in better outcomes. Current treatment requires random mapping biopsies along the length of Barrett’s, in addition to biopsy of visible abnormalities. As only 13 % of pre-cancerous changes appear as visible nodules or abnormalities, areas of dysplasia are often missed. Acetic acid chromoendoscopy (AAC) has been shown to improve detection of pre-cancerous and cancerous tissue in observational studies, but no randomized controlled trials (RCTs) have been performed to date. Patients and methods  A “tandem” endoscopy cross-over design. Participants will be randomized to endoscopy using mapping biopsies or AAC, in which dilute acetic acid is sprayed onto the surface of the esophagus, highlighting tissue through an whitening reaction and enhancing visibility of areas with cellular changes for biopsy. After 4 to 10 weeks, participants will undergo a repeat endoscopy, using the second method. Rates of recruitment and retention will be assessed, in addition to the estimated dysplasia detection rate, effectiveness of the endoscopist training program, and rates of adverse events (AEs). Qualitative interviews will explore participant and endoscopist acceptability of study design and delivery, and the acceptability of switching endoscopic techniques for Barrett's surveillance. Results  Endoscopists’ ability to diagnose dysplasia in Barrett’s esophagus can be improved. AAC may offer a simple, universally applicable, easily-acquired technique to improve detection, affording patients earlier diagnosis and treatment, reducing endoscopy time and pathology costs. The ABBA study will determine whether a crossover “tandem” endoscopy design is feasible and acceptable to patients and clinicians and gather outcome data to power a definitive trial. PMID:29340297

Treatment of fatigue with methylphenidate, modafinil and amantadine in multiple sclerosis (TRIUMPHANT-MS): Study design for a pragmatic, randomized, double-blind, crossover clinical trial.

PubMed

Nourbakhsh, Bardia; Revirajan, Nisha; Waubant, Emmanuelle

2018-01-01

Fatigue is the most common symptom of multiple sclerosis (MS). Amantadine, modafinil and amphetamine-like stimulants are commonly used in clinical practice for treatment of fatigue; however, the evidence supporting their effectiveness is sparse and conflicting. To describe the design of a trial study funded by Patient-Centered Outcome Research Institute (PCORI) that will compare the efficacy of commonly used fatigue medications in patients with MS. The study is a randomized, placebo-controlled, crossover, four-sequence, four-period, double-blind, multicenter trial of three commonly used medications for the treatment of MS-related fatigue (amantadine, modafinil, methylphenidate) versus placebo in fatigued subjects with MS. Adult patients with MS, with an Expanded Disability Status Scale of <7.0 are eligible to participate. Participants will be randomized to one of four predefined sequences of medication administration. Each sequence comprises four 6-week periods of treatment with one of the 3 study drugs or placebo, and three 2-week washout periods between medication periods. 136 participants will be randomized over two years in two academic centers in the United States starting in the Summer 2017. Complete enrollment is expected by early 2019. The primary outcome of the study is the modified fatigue impact scale (MFIS) score while participants receive the maximally tolerated dose of each study medication (or placebo). Safety and tolerability of the medications and heterogeneity of treatment effect will also be assessed. Results of the proposed study will provide evidence-based and personalized treatment options for patients affected by MS-related fatigue. Clinicaltrials.gov registration number: NCT03185065. Copyright © 2017 Elsevier Inc. All rights reserved.

Risk of new acute myocardial infarction hospitalization associated with use of oral and parenteral non-steroidal anti-inflammation drugs (NSAIDs): a case-crossover study of Taiwan's National Health Insurance claims database and review of current evidence.

PubMed

Shau, Wen-Yi; Chen, Hsi-Chieh; Chen, Shu-Ting; Chou, Hsu-Wen; Chang, Chia-Hsuin; Kuo, Chuei-Wen; Lai, Mei-Shu

2012-02-02

Previous studies have documented the increased cardiovascular risk associated with the use of some nonsteroidal anti-inflammatory drugs (NSAIDs). Despite this, many old NSAIDs are still prescribed worldwide. Most of the studies to date have been focused on specific oral drugs or limited by the number of cases examined. We studied the risk of new acute myocardial infarction (AMI) hospitalization with current use of a variety of oral and parenteral NSAIDs in a nationwide population, and compared our results with existing evidence. We conducted a case-crossover study using the Taiwan's National Health Insurance claim database, identifying patients with new AMI hospitalized in 2006. The 1-30 days and 91-120 days prior to the admission were defined as case and matched control period for each patient, respectively. Uses of NSAIDs during the respective periods were compared using conditional logistic regression and adjusted for use of co-medications. 8354 new AMI hospitalization patients fulfilled the study criteria. 14 oral and 3 parenteral NSAIDs were selected based on drug utilization profile among 13.7 million NSAID users. The adjusted odds ratio, aOR (95% confidence interval), for risk of AMI and use of oral and parenteral non-selective NSAIDs were 1.42 (1.29, 1.56) and 3.35 (2.50, 4.47), respectively, and significantly greater for parenteral than oral drugs (p for interaction<0.01). Ketorolac was associated with the highest AMI risk among both of oral and parenteral NSAIDs studied, the aORs were 2.02 (1.00, 4.09) and 4.27 (2.90, 6.29) respectively. Use of oral flurbiprofen, ibuprofen, sulindac, diclofenac, and parenteral ketoprofen were also significantly associated with increased AMI risk. The results of the present study were consistent with the majority of evidence from previous studies. The collective evidence revealed the tendency of increased AMI risk with current use of some NSAIDs. A higher AMI risk associated with use of parenteral NSAIDs was observed in the present study. Ketorolac had the highest associated risk in both oral and parenteral NSAIDs studied. Though further investigation to confirm the association is warranted, prescribing physicians and the general public should be cautious about the potential risk of AMI when using NSAIDs.

Multiscale multifractal detrended-fluctuation analysis of two-dimensional surfaces

NASA Astrophysics Data System (ADS)

Wang, Fang; Fan, Qingju; Stanley, H. Eugene

2016-04-01

Two-dimensional (2D) multifractal detrended fluctuation analysis (MF-DFA) has been used to study monofractality and multifractality on 2D surfaces, but when it is used to calculate the generalized Hurst exponent in a fixed time scale, the presence of crossovers can bias the outcome. To solve this problem, multiscale multifractal analysis (MMA) was recent employed in a one-dimensional case. MMA produces a Hurst surface h (q ,s ) that provides a spectrum of local scaling exponents at different scale ranges such that the positions of the crossovers can be located. We apply this MMA method to a 2D surface and identify factors that influence the results. We generate several synthesized surfaces and find that crossovers are consistently present, which means that their fractal properties differ at different scales. We apply MMA to the surfaces, and the results allow us to observe these differences and accurately estimate the generalized Hurst exponents. We then study eight natural texture images and two real-world images and find (i) that the moving window length (WL) and the slide length (SL) are the key parameters in the MMA method, that the WL more strongly influences the Hurst surface than the SL, and that the combination of WL =4 and SL =4 is optimal for a 2D image; (ii) that the robustness of h (2 ,s ) to four common noises is high at large scales but variable at small scales; and (iii) that the long-term correlations in the images weaken as the intensity of Gaussian noise and salt and pepper noise is increased. Our findings greatly improve the performance of the MMA method on 2D surfaces.

Design and evaluation of modified centerline rumble strips : final report.

DOT National Transportation Integrated Search

2017-03-08

A centerline rumble strip (CLRS) is primarily installed on the centerline of undivided two-lane and two-way roadways : to alert drivers that they are moving out of their intended travel lane. The main purpose of CLRSs is to reduce crossover : collisi...