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Sample records for 3-way crossover design

  1. Colloidal submicron-particle curcumin exhibits high absorption efficiency-a double-blind, 3-way crossover study.

    PubMed

    Sunagawa, Yoichi; Hirano, Sae; Katanasaka, Yasufumi; Miyazaki, Yusuke; Funamoto, Masafumi; Okamura, Nobuko; Hojo, Yuya; Suzuki, Hidetoshi; Doi, Osamu; Yokoji, Tsunehiro; Morimoto, Eriko; Takashi, Tsukasa; Ozawa, Hitomi; Imaizumi, Atsushi; Ueno, Morio; Kakeya, Hideaki; Shimatsu, Akira; Wada, Hiromichi; Hasegawa, Koji; Morimoto, Tatsuya

    2015-01-01

    Curcumin is a major constituent of the spice turmeric and has various biological activities, including anticancer, antioxidant, and anti-inflammatory properties, as well as alcohol detoxification. However, because of its poor absorption efficiency, it is difficult for orally administered curcumin to reach blood levels sufficient to exert its bioactivities. To overcome this problem, several curcumin preparations with a drug-delivery system (DDS) have been developed to increase the bioavailability of curcumin after oral administration, and tested as functional foods and potential medical agents in humans. We have also produced capsules containing Theracurmin, curcumin dispersed with colloidal submicron-particles. To evaluate the absorption efficiency of three types of DDS curcumin, we performed a double-blind, 3-way crossover study. We compared plasma curcumin levels after the administration of Theracurmin and 2 other capsule types of curcumin with DDS, BCM-95 (micronized curcumin with turmeric essential oils) and Meriva (curcumin-phospholipid). Nine healthy subjects (male/female=5/4, age: 24-32 y old) were administered these 3 preparations of DDS curcumin, at commonly used dosages. Six capsules of Theracurmin, 1 capsule of BCM-95, and 2 capsules of Meriva contain 182.4 ± 1.0, 279.3 ± 10.7, and 152.5 ± 20.3 mg of curcumin, respectively. The maximal plasma curcumin concentration (0-24 h) of Theracurmin was 10.7 to 5.6 times higher than those of BCM-95 and Meriva, respectively. Moreover, the area under the blood concentration-time curve at 0-24 h was found to be 11.0- and 4.6-fold higher with Theracurmin than BCM-95 and Meriva, respectively. These data indicate that Theracurmin exhibits a much higher absorption efficiency than other curcumin DDS preparations.

  2. The Design of Cluster Randomized Crossover Trials

    ERIC Educational Resources Information Center

    Rietbergen, Charlotte; Moerbeek, Mirjam

    2011-01-01

    The inefficiency induced by between-cluster variation in cluster randomized (CR) trials can be reduced by implementing a crossover (CO) design. In a simple CO trial, each subject receives each treatment in random order. A powerful characteristic of this design is that each subject serves as its own control. In a CR CO trial, clusters of subjects…

  3. A Single-Center, Open-Label, 3-Way Crossover Trial to Determine the Pharmacokinetic and Pharmacodynamic Interaction Between Nebivolol and Valsartan in Healthy Volunteers at Steady State

    PubMed Central

    Chen, Chun Lin; Desai-Krieger, Daksha; Ortiz, Stephan; Kerolous, Majid; Wright, Harold M.; Ghahramani, Parviz

    2015-01-01

    Combining different classes of antihypertensives is more effective for reducing blood pressure (BP) than increasing the dose of monotherapies. The aims of this phase I study were to investigate pharmacokinetic and pharmacodynamic interactions between nebivolol, a vasodilatory β1-selective blocker, and valsartan, an angiotensin II receptor blocker, and to assess safety and tolerability of the combination. This was a single-center, randomized, open-label, multiple-dose, 3-way crossover trial in 30 healthy adults aged 18–45 years. Participants were randomized into 1 of 6 treatment sequences (1:1:1:1:1:1) consisting of three 7-day treatment periods followed by a 7-day washout. Once-daily oral treatments comprised nebivolol (20 mg), valsartan (320 mg), and nebivolol–valsartan combination (20/320 mg). Outcomes included AUC0-τ,ss, Cmax,ss, Tmax,ss, changes in BP, pulse rate, plasma angiotensin II, plasma renin activity, 24-hour urinary aldosterone, and adverse events. Steady-state pharmacokinetic interactions were observed but deemed not clinically significant. Systolic and diastolic BP reduction was significantly greater with nebivolol–valsartan combination than with either monotherapy. The mean pulse rate associated with nebivolol and nebivolol–valsartan treatments was consistently lower than that associated with valsartan monotherapy. A sharp increase in mean day 7 plasma renin activity and plasma angiotensin II that occurred in valsartan-treated participants was significantly attenuated with concomitant nebivolol administration. Mean 24-hour urine aldosterone at day 7 was substantially decreased after combined treatment, as compared with either monotherapy. All treatments were safe and well tolerated. In conclusion, nebivolol and valsartan coadministration led to greater reductions in BP compared with either monotherapy; nebivolol and valsartan lower BP through complementary mechanisms. PMID:25853236

  4. Case-crossover design and its implementation in R

    PubMed Central

    2016-01-01

    Case-crossover design is a variation of case-control design that it employs persons’ history periods as controls. Case-crossover design can be viewed as the hybrid of case-control study and crossover design. Characteristic confounding that is constant within one person can be well controlled with this method. The relative risk and odds ratio, as well as their 95% confidence intervals (CIs), can be estimated using Cochran-Mantel-Haenszel method. R codes for the calculation are provided in the main text. Readers may adapt these codes to their own task. Conditional logistic regression model is another way to estimate odds ratio of the exposure. Furthermore, it allows for incorporation of other time-varying covariates that are not constant within subjects. The model fitting per se is not technically difficult because there is well developed statistical package. However, it is challenging to convert original dataset obtained from case report form to that suitable to be passed to clogit() function. R code for this task is provided and explained in the text. PMID:27761445

  5. Influence of an antivertiginous combination preparation of cinnarizine and dimenhydrinate on event-related potentials, reaction time and psychomotor performance--a randomized, double-blind, 3-way crossover study in healthy volunteers.

    PubMed

    Philipova, D; Tzenova, B; Iwanowitsch, A; Bognar-Steinberg, I

    2004-04-01

    In the present comparative, double-blind, 3-way crossover study, possible effects of an antivertiginous combination preparation on event-related potentials (ERPs) and performance were investigated. Twenty-one healthy volunteers received 4 doses (within 24 h) of a fixed combination of cinnarizine 20 mg and dimenhydrinate 40 mg (Arlevert, ARL), dimenhydrinate 50 mg, or a placebo, in randomized order at 1-week intervals. Auditory event-related potentials (ERPs), reaction time (RT) and psychometric tests were assessed before as well as 60 and 150 minutes after the intake of the 1st (Day 1) and the 4th (Day 2) dose of study medication. The evaluation was primarily based on the difference in the outcomes measured 150 min after the 4th dose (t5) and those before the start of medication intake (t0). None of the medications affected the latency and amplitude of the sensory ERP component N100, neither under passive listening nor under discrimination task conditions. The latency of P300 in response to the rare target tones (oddball paradigm and binary series), showed significant (p < 0.05) delays after 4 doses of dimenhydrinate (18-24 ms), and no significant differences between ARL (3-17 ms) and either dimenhydrinate or placebo (4-13 ms). Responses to nontarget tones remained almost unaffected after medication intake. The secondary analysis of the P300 amplitude showed the greatest decreases under DH in both active series, with no significant differences between ARL and either DH or placebo. The 3 medications did not significantly prolong RT nor did they impair the performance of psychometric tests, or cause significant shifts of current mood. The combination preparation ARL showed the lowest rate of adverse events (n = 1), followed by dimenhydrinate (n = 3) and placebo (n = 6). Two subjects withdrew because of adverse events, both after the intake of placebo. In conclusion, the results gave no evidence for an impairment of central information processing and psychomotor

  6. A single-dose, 3-way crossover pharmacokinetic comparison between immediate-release oxycodone hydrochloride with aversion technology (IRO-A, Oxecta), IRO-a with Niacin, and Oxycodone Hydrochloride (Roxicodone) in healthy adults under fasting conditions.

    PubMed

    Leibowitz, Mark T; Zamora, Cynthia A; Brzeczko, Albert W; Stark, Jeffrey G

    2014-01-01

    Snorting and intravenous use are common routes of administration for advanced opioid abusers. A tablet form of immediate-release oxycodone (IRO) developed using Aversion Technology combines immediate release (IR) oxycodone HCl with inactive functional excipients that are intended to discourage tampering associated with intranasal and intravenous abuse (IRO-A; Oxecta, Pfizer). The purpose of this single-dose, open-label, randomized, 3-period, 3-treatment crossover study was to evaluate the bioequivalence of IRO-A to the marketed immediate-release oxycodone HCl (IRO; Roxicodone, Xanodyne Pharmaceuticals Inc., Newport, KY). IRO-A was also compared with IRO-A with niacin, a product previously developed containing the same functional excipients plus niacin as an aversive agent to discourage oral overconsumption. Healthy adults (N = 40) aged 18-55 years received single 15-mg doses of IRO-A, IRO-A with niacin (60 mg), or IRO after fasting overnight. Naltrexone was administered to diminish opioid effects. Doses were separated by a ≥7-day washout. Plasma samples taken at designated time points were analyzed using liquid chromatography with tandem mass spectrometry. Geometric mean ratios for ln-transformed parameters for IRO-A and IRO were 92%, 104%, and 104% for Cmax, AUClast (AUC is area under the concentration-time curve), and AUCinf; 90% confidence intervals were within the accepted 80%-125% range. IRO-A was also bioequivalent to IRO-A with niacin. Adverse events were mild to moderate in intensity and typical of opioid therapy (nausea, headache, vomiting). Flushing only occurred when the subjects received the IRO-A with niacin treatment (9/37 subjects). The results demonstrated that IRO-A is bioequivalent to IRO and IRO-A with niacin. With features designed to discourage tampering associated with common forms of abuse, IRO-A may provide an alternative to conventional immediate-release oxycodone formulations.

  7. Design and numerical characterization of a crossover EBIS

    SciTech Connect

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

    2015-01-09

    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{sup −7} A/V{sup 3/2} for the realized gun system. In the interaction region the electron beam has a density of around 10 A/cm{sup 2} 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 1×10{sup 8} charges. Charge state breeding studies with CBSIM indicate for the noble gases as maximal achievable charge state Ar{sup 16+}, Kr{sup 30+} and Xe{sup 35+}. 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.

  8. 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. PMID:23539081

  9. Designer coordination polymers: dimensional crossover architectures and proton conduction.

    PubMed

    Yamada, Teppei; Otsubo, Kazuya; Makiura, Rie; Kitagawa, Hiroshi

    2013-08-21

    Coordination polymers (CPs) have large degrees of freedom in framework compositions and in the structures and environment of the inner pores. This review focuses on the recent significant progress achieved by controlling these degrees of freedom. Two breakthroughs are reviewed for constructing sophisticated structures of CP frameworks, especially in dimensional crossover regions. The first is the synthesis of quasi one-dimensional halogen-bridged coordinative tubes by applying state-of-the-art techniques of coordination chemistry. The electronic state of the coordinative tube was studied by structural, spectroscopic and theoretical methods and found to be distinct from conventional one-dimensional systems. The second breakthrough is the achievement of a quasi-two-dimensional architecture by combining Langmuir-Blodgett and layer-by-layer methods. Two-dimensional LB CP films were prepared on liquid; the films were stacked layer by layer, and a crystalline quasi-two-dimensional structure was constructed. This review also covers the design of the environment of the inner pore, where hydrogen bond networks with various acidic sites were modified. By appropriate design of the hydrogen bond network, proton-conductive CPs are invented, which are summarized in this review. Types of proton donor sites are discussed and classified, and superprotonic conductive CPs were achieved in these investigations. These results will provide new strategies for constructing functional materials for smart devices.

  10. Alternative Solutions for ANOVA Using 2-Way and 3-Way Completely Randomized Factorial Designs with Disproportional Cell Sizes.

    ERIC Educational Resources Information Center

    Pugh, Richard C.; And Others

    Three alternative solutions available for analysis of variance (ANOVA) using two-way and three-way completely randomized factorial designs with disproportional cell sizes across all two-way and three-way summary tables with no empty cells are discussed. These solutions are categorized as unique, sequential, and experimental. The procedures used,…

  11. A randomized, double-blind, positive-controlled, 3-way cross-over human experimental pain study of a TRPV1 antagonist (V116517) in healthy volunteers and comparison with preclinical profile.

    PubMed

    Arendt-Nielsen, Lars; Harris, Steve; Whiteside, Garth T; Hummel, Michele; Knappenberger, Terri; OʼKeefe, Sarah; Kapil, Ram; Kyle, Don

    2016-09-01

    This experimental, translational, experimental pain, single-center, randomized, double-blind, single-dose, 3-treatment, 3-period cross-over proof-of-concept volunteer trial studied the efficacy of a novel TRPV1 antagonist (V116517) on capsaicin- and UV-B-induced hyperalgesia. Heat and pressure pain thresholds, von Frey stimulus-response functions, and neurogenic inflammation were assessed together with safety. Each treatment period was 4 days. The 3 single oral treatments were 300 mg V116517, 400 mg celecoxib (a COX-2 inhibitor), and placebo. The heat pain detection and tolerance thresholds were increased significantly (P < 0.0001) by V116517. Heat pain detection and tolerance thresholds showed significantly less capsaicin hyperalgesia after V116517 (P = 0.004 and P < 0.0001, respectively). Celecoxib reduced UV-B-provoked pressure pain sensitization (P = 0.01). Laser Doppler flowmetry and erythema index after UV-B were significantly (P < 0.0001) reduced by celecoxib. Stimulus-response function in capsaicin-treated areas showed significant differences between both celecoxib and placebo and between V116517 and placebo. The body temperature showed no change, and no side effects were reported for any of the treatments. The TRPV1 antagonists and the COX-2 inhibitor showed different antihyperalgesic profiles indicating different clinical targets. In addition, the preclinical profile of V116517 in rat models of UV-B and capsaicin-induced hypersensitivity was compared with the human experimental data and overall demonstrated an alignment between 2 of the 3 end points tested. The TRPV1 antagonist showed a potent antihyperalgesic action without changing the body temperature but heat analgesia may be a potential safety issue. PMID:27168361

  12. Hypothesis testing and estimation in ordinal data under a simple crossover design.

    PubMed

    Lui, Kung-Jong; Chang, Kuang-Chao

    2012-01-01

    Since each patient serves as his/her own control, the crossover design can be of use to improve power as compared with the parallel-groups design in studying noncurative treatments to certain chronic diseases. Although the research studies on the crossover design have been quite intensive, the discussions on analyzing ordinal data under such a design are truly limited. We propose using the generalized odds ratio (GOR) for paired sample data to measure the relative effect on patient responses for both treatment and period in ordinal data under a simple crossover trial. Assuming the treatment and period effects are multiplicative, we note that one can easily derive the maximum likelihood estimator (LE) in closed forms for the GOR of treatment and period effects. We develop asymptotic and exact procedures for testing treatment and period effects. We further derive asymptotic and exact interval estimators for the GOR of treatment and period effects. We use the data taken from a crossover trial to assess the clarity of leaflet instructions between two devices among asthma patients to illustrate the use of these test procedures and estimators developed here. PMID:23075013

  13. Hypothesis testing and estimation in ordinal data under a simple crossover design.

    PubMed

    Lui, Kung-Jong; Chang, Kuang-Chao

    2012-01-01

    Since each patient serves as his/her own control, the crossover design can be of use to improve power as compared with the parallel-groups design in studying noncurative treatments to certain chronic diseases. Although the research studies on the crossover design have been quite intensive, the discussions on analyzing ordinal data under such a design are truly limited. We propose using the generalized odds ratio (GOR) for paired sample data to measure the relative effect on patient responses for both treatment and period in ordinal data under a simple crossover trial. Assuming the treatment and period effects are multiplicative, we note that one can easily derive the maximum likelihood estimator (LE) in closed forms for the GOR of treatment and period effects. We develop asymptotic and exact procedures for testing treatment and period effects. We further derive asymptotic and exact interval estimators for the GOR of treatment and period effects. We use the data taken from a crossover trial to assess the clarity of leaflet instructions between two devices among asthma patients to illustrate the use of these test procedures and estimators developed here.

  14. 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…

  15. The Use and Reporting of the Cross-Over Study Design in Clinical Trials and Systematic Reviews: A Systematic Assessment

    PubMed Central

    Hambleton, Ian; Dwan, Kerry

    2016-01-01

    Background Systematic reviews of treatment interventions in stable or chronic conditions often require the synthesis of clinical trials with a cross-over design. Previous work has indicated that methodology for analysing cross-over data is inadequate in trial reports and in systematic reviews assessing trials with this design. Objective We assessed systematic review methodology for synthesising cross-over trials among Cochrane Cystic Fibrosis and Genetic Disorders Group reviews published to July 2015, and assessed the quality of reporting among the cross-over trials included in these reviews. Methodology We performed data extraction of methodology and reporting in reviews, trials identified and trials included within reviews. Principal Findings We reviewed a total of 142 Cochrane systematic reviews including 53 reviews which synthesised evidence from 218 cross-over trials. Thirty-three (63%) Cochrane reviews described a clear and appropriate method for the inclusion of cross-over data, and of these 19 (56%) used the same method to analyse results. 145 cross-over trials were described narratively or treated as parallel trials in reviews but in 30 (21%) of these trials data existed in the trial reports to account for the cross-over design. At the trial level, the analysis and presentation of results were often inappropriate or unclear, with only 69 (32%) trials presenting results that could be included in meta-analysis. Conclusions Despite development of accessible, technical guidance and training for Cochrane systematic reviewers, statistical analysis and reporting of cross-over data is inadequate at both the systematic review and the trial level. Plain language and practical guidance for the inclusion of cross-over data in meta-analysis would benefit systematic reviewers, who come from a wide range of health specialties. Minimum reporting standards for cross-over trials are needed. PMID:27409076

  16. Assessing individual bioequivalence with high-order cross-over designs: a unified procedure.

    PubMed

    Hsuan, Francis C; Reeve, Russell

    2003-09-30

    The U.S. FDA's newly issued guidance on bioequivalence recommends the use of individual bioequivalence (IBE) for highly variable drugs and possibly for modified release dosage forms. The recommended approach to the analysis is to follow the methodology of Hyslop, Hsuan and Holder (HHH), based on a linear mixed model. A limitation of the HHH method is that it works only for uniform designs, such as RTRT/TRTR. In this paper, we present an alternative approach based on a multivariate model. The multivariate model is shown to be a strict superset of the linear mixed model and can successfully model data where the mixed model fails. Our multivariate approach coincides with the HHH method where the HHH method applies, but generalizes to any high-order cross-over design, such as the Balaam design, RTR/TRT, and TRSS/RSTT/STRR. We present numerical examples to demonstrate the proposed method, and examine its properties with a simulation study. PMID:12953284

  17. The MAP kinase pathway coordinates crossover designation with disassembly of synaptonemal complex proteins during meiosis.

    PubMed

    Nadarajan, Saravanapriah; Mohideen, Firaz; Tzur, Yonatan B; Ferrandiz, Nuria; Crawley, Oliver; Montoya, Alex; Faull, Peter; Snijders, Ambrosius P; Cutillas, Pedro R; Jambhekar, Ashwini; Blower, Michael D; Martinez-Perez, Enrique; Harper, J Wade; Colaiacovo, Monica P

    2016-02-27

    Asymmetric disassembly of the synaptonemal complex (SC) is crucial for proper meiotic chromosome segregation. However, the signaling mechanisms that directly regulate this process are poorly understood. Here we show that the mammalian Rho GEF homolog, ECT-2, functions through the conserved RAS/ERK MAP kinase signaling pathway in the C. elegans germline to regulate the disassembly of SC proteins. We find that SYP-2, a SC central region component, is a potential target for MPK-1-mediated phosphorylation and that constitutively phosphorylated SYP-2 impairs the disassembly of SC proteins from chromosomal domains referred to as the long arms of the bivalents. Inactivation of MAP kinase at late pachytene is critical for timely disassembly of the SC proteins from the long arms, and is dependent on the crossover (CO) promoting factors ZHP-3/RNF212/Zip3 and COSA-1/CNTD1. We propose that the conserved MAP kinase pathway coordinates CO designation with the disassembly of SC proteins to ensure accurate chromosome segregation.

  18. The MAP kinase pathway coordinates crossover designation with disassembly of synaptonemal complex proteins during meiosis

    PubMed Central

    Nadarajan, Saravanapriah; Mohideen, Firaz; Tzur, Yonatan B; Ferrandiz, Nuria; Crawley, Oliver; Montoya, Alex; Faull, Peter; Snijders, Ambrosius P; Cutillas, Pedro R; Jambhekar, Ashwini; Blower, Michael D; Martinez-Perez, Enrique; Harper, J Wade; Colaiacovo, Monica P

    2016-01-01

    Asymmetric disassembly of the synaptonemal complex (SC) is crucial for proper meiotic chromosome segregation. However, the signaling mechanisms that directly regulate this process are poorly understood. Here we show that the mammalian Rho GEF homolog, ECT-2, functions through the conserved RAS/ERK MAP kinase signaling pathway in the C. elegans germline to regulate the disassembly of SC proteins. We find that SYP-2, a SC central region component, is a potential target for MPK-1-mediated phosphorylation and that constitutively phosphorylated SYP-2 impairs the disassembly of SC proteins from chromosomal domains referred to as the long arms of the bivalents. Inactivation of MAP kinase at late pachytene is critical for timely disassembly of the SC proteins from the long arms, and is dependent on the crossover (CO) promoting factors ZHP-3/RNF212/Zip3 and COSA-1/CNTD1. We propose that the conserved MAP kinase pathway coordinates CO designation with the disassembly of SC proteins to ensure accurate chromosome segregation. DOI: http://dx.doi.org/10.7554/eLife.12039.001 PMID:26920220

  19. Indirect fuel cell based on a redox-flow battery with a new design to avoid crossover

    NASA Astrophysics Data System (ADS)

    Siroma, Zyun; Yamazaki, Shin-ichi; Fujiwara, Naoko; Asahi, Masafumi; Nagai, Tsukasa; Ioroi, Tsutomu

    2013-11-01

    A new design of a redox flow battery (RFB), which is composed of two subcells separated by a gas phase of hydrogen, is proposed to eliminate the crossover of ionic species between the anolyte and catholyte. This idea not only increases the possible combinations of the two electrolytes, but also opens up the prospect of a revival of the old idea of an indirect fuel cell, which is composed of an RFB and two chemical reactors to regenerate the electrolytes using a fuel and oxygen. This paper describes the operation of a subcell as a component of an indirect fuel cell system. In the cycling test, oxidation/reduction of the electroactive species in each electrolyte were repeated with a hydrogen electrode as the counter electrode. This result demonstrates the possibility of this newly proposed RFB without crossover. In the operation of the subcell with a chemical reactor, a molecular catalyst (a rhodium porphyrin) was dissolved in the anolyte, and then a fuel was bubbled in the anolyte reservoir. As the electroactive species was reduced by the fuel, a steady-state oxidation current was observed at the cell. This demonstrates the negative half of the newly proposed indirect fuel cell.

  20. Crossover studies with survival outcomes.

    PubMed

    Buyze, Jozefien; Goetghebeur, Els

    2013-12-01

    Crossover designs are well known to have major advantages when comparing the effect of two treatments which do not interact. With a right-censored survival endpoint, however, this design is quickly abandoned in favour of the more costly parallel design. Motivated by human immunodeficiency virus (HIV) prevention studies which lacked power, we evaluate what may be gained in this setting and compare parallel with crossover designs. In a heterogeneous population, we find and explain a substantial increase in power for the crossover study using a non-parametric logrank test. With frailties in a proportional hazards model, crossover designs equally lead to substantially smaller variance for the subject-specific hazard ratio (HR), while the population-averaged HR sees negligible gain. Its efficiency benefit is recovered when the population-averaged HR is reconstructed from estimated subject-specific hazard rates. We derive the time point for treatment crossover that optimizes efficiency and end with the analysis of two recent HIV prevention trials. We find that a Cellulose sulphate trial could have hardly gained efficiency from a crossover design, while a Nonoxynol-9 trial stood to gain substantial power. We conclude that there is a role for effective crossover designs in important classes of survival problems. PMID:21715438

  1. Calcium from salmon and cod bone is well absorbed in young healthy men: a double-blinded randomised crossover design

    PubMed Central

    2010-01-01

    Background Calcium (Ca) - fortified foods are likely to play an important role in helping the consumer achieve an adequate Ca intake, especially for persons with a low intake of dairy products. Fish bones have a high Ca content, and huge quantities of this raw material are available as a by-product from the fish industry. Previously, emphasis has been on producing high quality products from fish by-products by use of bacterial proteases. However, documentation of the nutritional value of the enzymatically rinsed Ca-rich bone fraction remains unexplored. The objective of the present study was to assess the bioavailability of calcium in bones of Atlantic salmon (oily fish) and Atlantic cod (lean fish) in a double-blinded randomised crossover design. Methods Ca absorption was measured in 10 healthy young men using 47Ca whole body counting after ingestion of a test meal extrinsically labelled with the 47Ca isotope. The three test meals contained 800 mg of Ca from three different calcium sources: cod bones, salmon bones and control (CaCO3). Results Mean Ca absorption (± SEE) from the three different Ca sources were 21.9 ± 1.7%, 22.5 ± 1.7% and 27.4 ± 1.8% for cod bones, salmon bones, and control (CaCO3), respectively. Conclusion We conclude that bones from Atlantic salmon and Atlantic cod are suitable as natural Ca sources in e.g. functional foods or as supplements. PMID:20646299

  2. 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. PMID:22874219

  3. Comparing the effects of infrastructure on bicycling injury at intersections and non-intersections using a case–crossover design

    PubMed Central

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

    2013-01-01

    Background This study examined the impact of transportation infrastructure at intersection and non-intersection locations on bicycling injury risk. Methods In Vancouver and Toronto, we studied adult cyclists who were injured and treated at a hospital emergency department. A case–crossover design compared the infrastructure of injury and control sites within each injured bicyclist's route. Intersection injury sites (N=210) were compared to randomly selected intersection control sites (N=272). Non-intersection injury sites (N=478) were compared to randomly selected non-intersection control sites (N=801). Results At intersections, the types of routes meeting and the intersection design influenced safety. Intersections of two local streets (no demarcated traffic lanes) had approximately one-fifth the risk (adjusted OR 0.19, 95% CI 0.05 to 0.66) of intersections of two major streets (more than two traffic lanes). Motor vehicle speeds less than 30 km/h also reduced risk (adjusted OR 0.52, 95% CI 0.29 to 0.92). Traffic circles (small roundabouts) on local streets increased the risk of these otherwise safe intersections (adjusted OR 7.98, 95% CI 1.79 to 35.6). At non-intersection locations, very low risks were found for cycle tracks (bike lanes physically separated from motor vehicle traffic; adjusted OR 0.05, 95% CI 0.01 to 0.59) and local streets with diverters that reduce motor vehicle traffic (adjusted OR 0.04, 95% CI 0.003 to 0.60). Downhill grades increased risks at both intersections and non-intersections. Conclusions These results provide guidance for transportation planners and engineers: at local street intersections, traditional stops are safer than traffic circles, and at non-intersections, cycle tracks alongside major streets and traffic diversion from local streets are safer than no bicycle infrastructure. PMID:23411678

  4. Variable-rung design for a mixed-valence two-legged ladder system situated in a dimensional crossover region.

    PubMed

    Otsubo, Kazuya; Kobayashi, Atsushi; Sugimoto, Kunihisa; Fujiwara, Akihiko; Kitagawa, Hiroshi

    2014-01-21

    Ladder systems situated in a crossover from one dimensionality to two dimensionalities have been an attractive research target, because the physical properties, which are associated with dimensionality, are strongly dependent on the number of constituent legs. However, control of the intraladder configuration and electronic properties based on the substitution of structural components remain challenging tasks in materials science. On the other hand, structural design using coordination chemistry offers crucial advantages for architectural and electronic variations through substitutions of metal-organic building blocks. Here, we show the rational design and electronic properties of novel metal complex-based two-legged ladder compounds with several organic rung units: 4,4'-bipyridine, trans-1,4-diaminocyclohexane, and 4,4'-azopyridine. Single-crystal X-ray studies show that these two-legged ladder compounds are composed of halogen-bridged mixed-valence one-dimensional chains (MX chains) as their constituent legs. Depending on the molecular shape of the organic rung units, unique configurations of two-legged ladder lattices with periodic distortion of the legs are achieved. In addition, the electronic absorption spectra show that intervalence charge-transfer (IVCT) band gap of the two-legged ladder system increases with increasing degree of distortion of the leg. We have demonstrated for the first time that a two-legged ladder system shows a unique relationship between IVCT energy and the distortion parameter of the leg, as distinct from a single MX chain system. These systematic investigations, not only of configurations based on the rung variation but also of electronic states in metal-organic ladder system, provide the possibility for wide and rational tunings of physical and electronic properties of metal complex-based functional materials. PMID:24392762

  5. 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

  6. Attitudes towards massage modify effects of manual therapy in breast cancer survivors: a randomised clinical trial with crossover design.

    PubMed

    Fernández-Lao, C; Cantarero-Villanueva, I; Díaz-Rodríguez, L; Cuesta-Vargas, A I; Fernández-Delas-Peñas, C; Arroyo-Morales, M

    2012-03-01

    Our aims were to investigate the immediate effect of myofascial release on heart rate variability and mood state, and the influence of attitude towards massage in breast cancer survivors with cancer-related fatigue. Twenty breast cancer survivors reporting moderate to high cancer-related fatigue participated in this crossover study. All patients presented to the laboratory at the same time of the day on two occasions separated by a 2-week interval. At each session, they received either a massage intervention or control intervention. Holter electrocardiogram recordings and Profile of Mood States questionnaire (six domains: tension-anxiety, depression-dejection, anger-hostility, vigour, fatigue, confusion) were obtained before and immediately after each intervention. The attitude towards massage scale was collected before the first session in all breast cancer survivors. The results showed a significant session × time interaction for standard deviation of the normal-to-normal interval (SDNN) (F= 5.063, P= 0.039), square root of mean squared differences of successive normal-to-normal intervals (RMSSD) (F= 8.273, P= 0.010), high-frequency component (HF) (F= 7.571, P= 0.013), but not for index heart rate variability (F= 3.451, P= 0.080), low-frequency component (LF) (F= 0.014, P= 0.997) and ratio LF/HF (F= 3.680, P= 0.072): significant increases in SDNN, RMSSD and HF domain (P < 0.05) were observed after the manual therapy intervention, with no changes after placebo (P > 0.6). No influence of the attitude scale on heart rate variability results was found. A significant session × time interaction was also found for fatigue (F= 5.101, P= 0.036) and disturbance of mood (F= 6.690, P= 0.018) scales of the Profile of Mood States: patients showed a significant decrease in fatigue and disturbance of mood (P < 0.001) after manual therapy, with no changes after placebo (P > 0.50). A significant influence of the attitude scale was observed in tension-anxiety, depression

  7. Relevance of supramolecular interactions, texture and lattice occupancy in the designer iron(II) spin crossover complexes

    SciTech Connect

    Naik, Anil D.; Tinant, Bernard; Muffler, Kai; Wolny, Juliusz A.; Schuenemann, Volker; Garcia, Yann

    2009-06-15

    New Fe{sup II} complexes of formula [Fe(3-Br-phen){sub 2}(NCS){sub 2}].Solvent (Solvent=0.5 CH{sub 3}OH (1), 2 CH{sub 2}Cl{sub 2} (2), desolvation of 2 (3), 0.5 CH{sub 3}COCH{sub 3} (4) and 0 (5)) have been synthesized. {sup 57}Fe Moessbauer and magnetic investigation reveal unique features atypical of classic [Fe(phen){sub 2}(NCS){sub 2}] polymorphs. Complex 1, prepared by precipitation in MeOH, undergoes upon cooling below room temperature an incomplete and gradual thermally induced spin conversion, while 4 prepared by an extraction method remains mostly in the low-spin state. The non solvated compounds 3 and 5, display a more abrupt spin crossover on cooling around T{sub 1/2}=175 K and T{sub 1/2}=198 K, respectively. Defects/soft lattice inclusion due to different methods of material synthesis, extent of aging, reaction medium and associated solvent molecules have enormous influence on the particle size and magnetic properties of these complexes. Scanning electron micrographs helps to establish a logical relationship among methods employed for synthesis, texture of materials and their effect on magnetic properties. The crystal structure of 2 determined in the monoclinic space group P2/c (100 K) reveals a mononuclear complex consisting of a distorted FeN{sub 6} octahedron in the low-spin state, constructed from two 3-bromo-1, 10-phenanthroline and two isothiocyanato anions in cis position. Intermolecular interactions between mononuclear units of the S...Br, S...C(H) and pi-pi type afford a 2D supramolecular network. DFT calculations for the single molecule 2 reveals an energy difference between high-spin and low-spin isomers of 7 kJ/mol suggesting a slight destabilization of the low-spin state compared to [Fe(phen){sub 2}(NCS){sub 2}]. Normal co-ordinate analysis was also carried out for 3 and compared with experimental temperature dependent Raman spectra for 5. - Graphical abstract: New Fe{sup II} complexes of formula [Fe(3-Br-phen){sub 2}(NCS){sub 2}].Solvent

  8. Study design and methods for a randomized crossover trial substituting brown rice for white rice on diabetes risk factors in India.

    PubMed

    Wedick, Nicole M; Sudha, Vasudevan; Spiegelman, Donna; Bai, Mookambika Ramya; Malik, Vasanti S; Venkatachalam, Siva Sankari; Parthasarathy, Vijayalaksmi; Vaidya, Ruchi; Nagarajan, Lakshmipriya; Arumugam, Kokila; Jones, Clara; Campos, Hannia; Krishnaswamy, Kamala; Willett, Walter; Hu, Frank B; Anjana, Ranjit Mohan; Mohan, Viswanathan

    2015-01-01

    India has the second largest number of people with diabetes in the world following China. Evidence indicates that consumption of whole grains can reduce the risk of type 2 diabetes. This article describes the study design and methods of a trial in progress evaluating the effects of substituting whole grain brown rice for polished (refined) white rice on biomarkers of diabetes risk (glucose metabolism, dyslipidemia, inflammation). This is a randomized controlled clinical trial with a crossover design conducted in Chennai, India among overweight but otherwise healthy volunteers aged 25-65 y with a body mass index ≥23 kg/m(2) and habitual rice consumption ≥200 g/day. The feasibility and cultural appropriateness of this type of intervention in the local environment will also be examined. If the intervention is efficacious, the findings can be incorporated into national-level policies which could include the provision of brown rice as an option or replacement for white rice in government institutions and food programs. This relatively simple dietary intervention has the potential to substantially diminish the burden of diabetes in Asia and elsewhere.

  9. Study design and methods for a randomized crossover trial substituting brown rice for white rice on diabetes risk factors in India

    PubMed Central

    Wedick, Nicole M.; Vasudevan, Sudha; Spiegelman, Donna; Bai, Ramya; Malik, Vasanti; Venkatachalam, Siva Sankari; Parthasarathy, Vijayalaksmi; Vaidya, Ruchi; Nagarajan, Lakshmipriya; Arumugam, Kokila; Jones, Clara; Campos, Hannia; Krishnaswamy, Kamala; Willett, Walter; Hu, Frank B.; Mohan, Anjana Ranjit; Viswanathan, Mohan

    2016-01-01

    India has the second largest number of people with diabetes in the world following China. Evidence indicates that consumption of whole grains can reduce risk of type 2 diabetes. This manuscript describes the study design and methods of a trial in progress evaluating the effects of substituting whole grain brown rice for polished (refined) white rice on biomarkers of diabetes risk (glucose metabolism, dyslipidemia, inflammation). This is a randomized controlled clinical trial with a crossover design conducted in Chennai, India among overweight but otherwise healthy volunteers aged 25–65y with a body mass index ≥23kg/m2 and habitual rice consumption ≥200grams/day. The feasibility and cultural appropriateness of this type of intervention in the local environment will also be examined. If the intervention is efficacious, the findings can be incorporated into national-level policies which could include the provision of brown rice as an option or replacement for white rice in government institutions and food programs. This relatively simple dietary intervention has the potential to substantially diminish the burden of diabetes in Asia and elsewhere. PMID:26017321

  10. The effect of intranasal oxytocin versus placebo treatment on the autonomic responses to human sounds in autism: a single-blind, randomized, placebo-controlled, crossover design study

    PubMed Central

    2014-01-01

    Background Many individuals with autism spectrum disorders (ASD) have difficulty with verbal communication, which might be due to a lack of spontaneous orientation toward social auditory stimuli. Previous studies have shown that a single dose of oxytocin improves speech comprehension in autism. The primary aim of this study was to investigate whether the orientation behaviors toward human sounds are different for neurotypical (NT) adults and adults with ASD and whether oxytocin has an effect on their orientation behaviors toward human sounds. Methods This was a randomized, placebo-controlled, within-subject, crossover design study of intranasal oxytocin versus placebo in 13 NT adults and 16 adults with ASD. Subjects were randomized to 24 IU intranasal oxytocin or placebo on different days, and they were blind to the treatment. The participants then listened passively to human and non-human affective sounds while their skin conductance responses (SCRs) and the changes in peripheral blood vessel constriction were monitored as an indicator of spontaneous orientation. The monitored data were analyzed by a mixed-design ANOVA. Results Oxytocin enhanced the difference between the SCRs to human and non-human sounds in both the NT and ASD groups (F(1,56) = 6.046, p = 0.017). Further correlation coefficient analysis showed significant correlations between this SCR difference and the scores in the autism spectrum quotient ‘attention to detail’ and ‘social skill’ subscales and interpersonal reactivity index and social functioning scale in the ASD group. Oxytocin was well tolerated, and no serious adverse effects were reported. Conclusions The difference in SCRs implies that oxytocin nasal spray may enhance orientation behaviors toward human sounds in the presence of other environmental sounds in both ASD and NT adults. Trial registration UMIN-CTR Clinical Trial, Unique trial number: UMIN000005809 PMID:24576333

  11. Bioavailability and inter-conversion of sulforaphane and erucin in human subjects consuming broccoli sprouts or broccoli supplement in a cross-over study design

    PubMed Central

    Clarke, John D.; Hsu, Anna; Riedl, Ken; Bella, Deborah; Schwartz, Steven J.; Stevens, Jan F.; Ho, Emily

    2011-01-01

    Broccoli consumption may reduce the risk of various cancers and many broccoli supplements are now available. The bioavailability and excretion of the mercapturic acid pathway metabolites isothiocyanates after human consumption of broccoli supplements has not been tested. Two important isothiocyanates from broccoli are sulforaphane and erucin. We employed a cross-over study design in which 12 subjects consumed 40 grams of fresh broccoli sprouts followed by a 1 month washout period and then the same 12 subjects consumed 6 pills of a broccoli supplement. As negative controls for isothiocyanate consumption four additional subjects consumed alfalfa sprouts during the first phase and placebo pills during the second. Blood and urine samples were collected for 48 hours during each phase and analyzed for sulforaphane and erucin metabolites using LC-MS/MS. The bioavailability of sulforaphane and erucin is dramatically lower when subjects consume broccoli supplements compared to fresh broccoli sprouts. The peaks in plasma concentrations and urinary excretion were also delayed when subjects consumed the broccoli supplement. GSTP1 polymorphisms did not affect the metabolism or excretion of sulforaphane or erucin. Sulforaphane and erucin are able to interconvert in vivo and this interconversion is consistent within each subject but variable between subjects. This study confirms that consumption of broccoli supplements devoid of myrosinase activity does not produce equivalent plasma concentrations of the bioactive isothiocyanate metabolites compared to broccoli sprouts. This has implications for people who consume the recommended serving size (1 pill) of a broccoli supplement and believe they are getting equivalent doses of isothiocyanates. PMID:21816223

  12. Cardiovascular responses to the ingestion of sugary drinks using a randomised cross-over study design: Does glucose attenuate the blood pressure-elevating effect of fructose?

    PubMed

    Grasser, Erik K; Dulloo, Abdul; Montani, Jean-Pierre

    2014-07-28

    Overconsumption of sugar-sweetened beverages has been implicated in the pathogenesis of CVD. The objective of the present study was to elucidate acute haemodynamic and microcirculatory responses to the ingestion of sugary drinks made from sucrose, glucose or fructose at concentrations similar to those often found in commercial soft drinks. In a randomised cross-over study design, twelve young healthy human subjects (seven men) ingested 500 ml tap water in which was dissolved 60 g of either sucrose, glucose or fructose, or an amount of fructose equivalent to that present in sucrose (i.e. 30 g fructose). Continuous cardiovascular monitoring was performed for 30 min before and at 60 min after ingestion of sugary drinks, and measurements included beat-to-beat blood pressure (BP) and impedance cardiography. Additionally, microvascular endothelial function testing was performed after iontophoresis of acetylcholine and sodium nitroprusside using laser Doppler flowmetry. Ingestion of fructose (60 or 30 g) increased diastolic and mean BP to a greater extent than the ingestion of 60 g of either glucose or sucrose (P< 0.05). Ingestion of sucrose and glucose increased cardiac output (CO; P< 0.05), index of contractility (P< 0.05) and stroke volume (P< 0.05), but reduced total peripheral resistance (TPR; P< 0.05), which contrasts with the tendency of fructose (60 and 30 g) to increase resistance. Microvascular endothelial function did not differ in response to the ingestion of various sugary drinks. In conclusion, ingestion of fructose, but not sucrose, increases BP in healthy human subjects. Although sucrose comprises glucose and fructose, its changes in TPR and CO are more related to glucose than to fructose. PMID:24780643

  13. Cardiovascular responses to the ingestion of sugary drinks using a randomised cross-over study design: Does glucose attenuate the blood pressure-elevating effect of fructose?

    PubMed

    Grasser, Erik K; Dulloo, Abdul; Montani, Jean-Pierre

    2014-07-28

    Overconsumption of sugar-sweetened beverages has been implicated in the pathogenesis of CVD. The objective of the present study was to elucidate acute haemodynamic and microcirculatory responses to the ingestion of sugary drinks made from sucrose, glucose or fructose at concentrations similar to those often found in commercial soft drinks. In a randomised cross-over study design, twelve young healthy human subjects (seven men) ingested 500 ml tap water in which was dissolved 60 g of either sucrose, glucose or fructose, or an amount of fructose equivalent to that present in sucrose (i.e. 30 g fructose). Continuous cardiovascular monitoring was performed for 30 min before and at 60 min after ingestion of sugary drinks, and measurements included beat-to-beat blood pressure (BP) and impedance cardiography. Additionally, microvascular endothelial function testing was performed after iontophoresis of acetylcholine and sodium nitroprusside using laser Doppler flowmetry. Ingestion of fructose (60 or 30 g) increased diastolic and mean BP to a greater extent than the ingestion of 60 g of either glucose or sucrose (P< 0.05). Ingestion of sucrose and glucose increased cardiac output (CO; P< 0.05), index of contractility (P< 0.05) and stroke volume (P< 0.05), but reduced total peripheral resistance (TPR; P< 0.05), which contrasts with the tendency of fructose (60 and 30 g) to increase resistance. Microvascular endothelial function did not differ in response to the ingestion of various sugary drinks. In conclusion, ingestion of fructose, but not sucrose, increases BP in healthy human subjects. Although sucrose comprises glucose and fructose, its changes in TPR and CO are more related to glucose than to fructose.

  14. A conditional analysis for two-treatment multiple-period crossover designs with binomial or poisson outcomes and subjects who drop out.

    PubMed

    McKnight, B; Van den Eeden, S K

    1993-05-15

    We propose a conditional analysis for outcome data on numbers of recurrent symptoms arising in a two-treatment, multiple-period crossover trial. Conditioning on subject-specific totals removes any dependence on mean subject-specific symptom rates and permits the use of standard software to perform regression analysis to examine treatment, period, carryover and interaction effects. The addition of offsets to the regression equations allows the incorporation of data from subjects who do not complete all periods in the trial. We apply the proposed method to data from a crossover trial and discuss its advantages and disadvantages.

  15. Design of a randomized controlled double-blind crossover clinical trial to assess the effects of saliva substitutes on bovine enamel and dentin in situ

    PubMed Central

    2011-01-01

    Background Hyposalivation is caused by various syndromes, diabetes, drugs, inflammation, infection, or radiotherapy of the salivary glands. Patients with hyposalivation often show an increased caries incidence. Moreover, hyposalivation is frequently accompanied by oral discomfort and impaired oral functions, and saliva substitutes are widely used to alleviate oral symptoms. However, preference of saliva substitutes due to taste, handling, and relief of oral symptoms has been discussed controversially. Some of the marketed products have shown demineralizing effects on dental hard tissues in vitro. This demineralizing potential is attributed to the undersaturation with respect to calcium phosphates. Therefore, it is important to modify the mineralizing potential of saliva substitutes to prevent carious lesions. Thus, the aim of the present study was to evaluate the effects of a possible remineralizing saliva substitute (SN; modified Saliva natura) compared to a demineralizing one (G; Glandosane) on mineral parameters of sound bovine dentin and enamel as well as on artificially demineralized enamel specimens in situ. Moreover, oral well-being after use of each saliva substitute was recorded. Methods/Design Using a randomized, double-blind, crossover, phase II/III in situ trial, volunteers with hyposalivation utilize removable dentures containing bovine specimens during the experimental period. The volunteers are divided into two groups, and are required to apply both saliva substitutes for seven weeks each. After both test periods, differences in mineral loss and lesion depth between values before and after exposure are evaluated based on microradiographs. The oral well-being of the volunteers before and after therapy is determined using questionnaires. With respect to the microradiographic analysis, equal mineral losses and lesion depths of enamel and dentin specimens during treatment with SN and G, and no differences in patients' experienced oral comfort after SN

  16. Modelling of the PROTO-2 crossover network

    NASA Astrophysics Data System (ADS)

    Proulx, G. A.; Lackner, H.; Spence, P.; Wright, T. P.

    In order to drive a double ring, symmetrically fed bremsstrahlung diode, the PROTO II accelerator was redesigned. The radially converging triplate water line was reconfigured to drive radial converging triplate lines in parallel. The four output lines were connected to the two input lines via an electrically enclosed tubular crossover network. Low-voltage Time Domain Reflectrometry (TDR) experiments were conducted on a full scale water immersed model of one section of the crossover network as an aid in this design. A lumped element analysis of the power flow through the network was inadequate in explaining the observed wave transmission and reflection characteristics. A more detailed analysis was performed with a circuit code in which we considered both localized lump-element and transmission line features of the crossover network. Experimental results of the model tests are given and compared with the circuit simulations.

  17. A randomized crossover-design study to investigate the plaque removal efficacy of two power toothbrushes: Philips Sonicare Flexcare and Oral-B Triumph.

    PubMed

    Putt, Mark S; Milleman, Jeffery L; Jenkins, Wendy; Schmitt, Paul; Master, Aditi S; Strate, Joerg

    2008-01-01

    The Sonicare FlexCare and the Oral-B Triumph Professional Care 9000 power toothbrushes were compared in a single-use, examiner-masked, crossover clinical trial. Outcomes were evaluated using the Turesky Modified Quigley-Hein (TMQH) plaque index. Percent reduction in overall plaque score because of toothbrushing was the primary efficacy measure. Subjects were required to have a TMQH score > or = 1.8 at screening after refraining from oral hygiene for 24 hours. The study included three visits. At visit 1, subjects were randomized to one of two treatment sequences, given their first toothbrush and toothpaste, and instructed to use them twice daily for 2 minutes during a 1-week familiarization phase. Before visit 2, subjects again refrained from oral hygiene for 24 hours. At this visit, plaque scores were assessed before and after a 2-minute supervised brushing episode, then the second test product was issued. Familiarization, plaque accumulation, and clinical examinations were the same for both product use periods. Data were analyzed using a linear mixed effects model with subject as a grouping factor. Treatment effects were expressed as mean values and the appropriate 95% confidence intervals (CI). Ninety-six subjects were screened with 93 subjects completing the study. The sample's TMQH score at Visit 1 was 3.18 +/- 0.42 (mean +/- standard deviation [SD]). Full-mouth prebrushing plaque scores were 2.85 +/- 0.49 for FlexCare and 2.94 +/- 0.45 for Triumph. Respective full-mouth reductions in overall plaque score were 38.02% +/- 15.14% and 30.43% +/- 14.05%. The estimated treatment effect, expressed as difference between FlexCare and Triumph in percent plaque index reduction, was 7.59% with a 95% CI from 4.79% to 10.40%. Similar differences were observed for all subregions, including anterior, posterior, interproximal, and interproximal posterior sites. The same protocol design was used at an earlier study in another center. The combined overall treatment effect from

  18. A randomized crossover-design study to investigate the plaque removal efficacy of two power toothbrushes: Philips Sonicare Flexcare and Oral-B Triumph.

    PubMed

    Putt, Mark S; Milleman, Jeffery L; Jenkins, Wendy; Schmitt, Paul; Master, Aditi S; Strate, Joerg

    2008-01-01

    The Sonicare FlexCare and the Oral-B Triumph Professional Care 9000 power toothbrushes were compared in a single-use, examiner-masked, crossover clinical trial. Outcomes were evaluated using the Turesky Modified Quigley-Hein (TMQH) plaque index. Percent reduction in overall plaque score because of toothbrushing was the primary efficacy measure. Subjects were required to have a TMQH score > or = 1.8 at screening after refraining from oral hygiene for 24 hours. The study included three visits. At visit 1, subjects were randomized to one of two treatment sequences, given their first toothbrush and toothpaste, and instructed to use them twice daily for 2 minutes during a 1-week familiarization phase. Before visit 2, subjects again refrained from oral hygiene for 24 hours. At this visit, plaque scores were assessed before and after a 2-minute supervised brushing episode, then the second test product was issued. Familiarization, plaque accumulation, and clinical examinations were the same for both product use periods. Data were analyzed using a linear mixed effects model with subject as a grouping factor. Treatment effects were expressed as mean values and the appropriate 95% confidence intervals (CI). Ninety-six subjects were screened with 93 subjects completing the study. The sample's TMQH score at Visit 1 was 3.18 +/- 0.42 (mean +/- standard deviation [SD]). Full-mouth prebrushing plaque scores were 2.85 +/- 0.49 for FlexCare and 2.94 +/- 0.45 for Triumph. Respective full-mouth reductions in overall plaque score were 38.02% +/- 15.14% and 30.43% +/- 14.05%. The estimated treatment effect, expressed as difference between FlexCare and Triumph in percent plaque index reduction, was 7.59% with a 95% CI from 4.79% to 10.40%. Similar differences were observed for all subregions, including anterior, posterior, interproximal, and interproximal posterior sites. The same protocol design was used at an earlier study in another center. The combined overall treatment effect from

  19. A mobile application improves therapy-adherence rates in elderly patients undergoing rehabilitation: A crossover design study comparing documentation via iPad with paper-based control.

    PubMed

    Mertens, Alexander; Brandl, Christopher; Miron-Shatz, Talya; Schlick, Christopher; Neumann, Till; Kribben, Andreas; Meister, Sven; Diamantidis, Clarissa Jonas; Albrecht, Urs-Vito; Horn, Peter; Becker, Stefan

    2016-09-01

    Medication adherence is crucial for success in the management of patients with chronic conditions. This study analyzes whether a mobile application on a tablet aimed at supporting drug intake and vital sign parameter documentation affects adherence in elderly patients.Patients with coronary heart disease and no prior knowledge of tablet computers were recruited. They received a personal introduction to the mobile application Medication Plan, installed on an Apple iPad. The study was conducted using a crossover design with 3 sequences: initial phase, interventional phase (28 days of using the app system), and comparative phase (28 days of using a paper diary). Users experienced the interventional and comparative phases alternately.A total of 24 patients (12 males; mean age 73.8 years) were enrolled in the study. The mean for subjectively assessed adherence (A14-scale; 5-point Likert scale, from "never" to "very often" which results in a score from 0 to 56) before the study was 50.0 (SD = 3.44). After both interventions there was a significant increase, which was more pronounced after the interventional phase (54.0; SD = 2.01) than after the comparative phase (52.6; SD = 2.49) (for all pairs after both interventions, P <0.001). Neither medical conditions nor the number of drug intake (amount and frequency of drug taking) per day affected subjective adherence. Logging data showed a significantly stronger adherence for the medication app than the paper system for both blood pressure recordings (P <0.001) and medication intake (P = 0.033). The majority of participants (n = 22) stated that they would like to use the medication app in their daily lives and would not need further assistance with the app.A mobile app for medication adherence increased objectively and subjectively measured adherence in elderly users undergoing rehabilitation. The findings have promising clinical implications: digital tools can assist chronic disease patients achieve adherence to

  20. Crossover sexual offenses.

    PubMed

    Heil, Peggy; Ahlmeyer, Sean; Simons, Dominique

    2003-10-01

    Crossover sexual offenses are defined as those in which victims are from multiple age, gender, and relationship categories. This study investigates admissions of crossover sexual offending from sex offenders participating in treatment who received polygraph testing. For 223 incarcerated and 266 paroled sexual offenders, sexual offenses were recorded from criminal history records and admissions during treatment coupled with polygraph testing. The majority of incarcerated offenders admitted to sexually assaulting both children and adults from multiple relationship types. In addition, there was a substantial increase in offenders admitting to sexually assaulting victims from both genders. In a group of incarcerated offenders who sexually assaulted children, the majority of offenders admitted to sexually assaulting both relatives and nonrelatives, and there was a substantial increase in the offenders admitting to assaulting both male and female children. Although similar trends were observed for the sample of parolees, the rates were far less dramatic. Parolees appeared to have greater levels of denial, had participated in fewer treatment sessions, and perceived greater supervision restrictions as a result of admitting additional offenses. These findings support previous research indicating that many sexual offenders do not exclusively offend against a preferred victim type. PMID:14571530

  1. MS-Electronic Nose Performance Improvement Using GC Retention Times And 2-Way And 3-Way Data Processing Methods

    SciTech Connect

    Burian, Cosmin; Llobet, Eduard; Vilanova, Xavier; Canellas, Nicolau; Brezmes, Jesus; Vinaixa, Maria; Correig, Xavier

    2009-05-23

    We have designed a challenging experimental sample set in the form of 20 solutions with a high degree of similarity in order to study whether the addition of chromatographic separation information improves the performance of regular MS based electronic noses. In order to make an initial study of the approach, two different chromatographic methods were used. By processing the data of these experiments with 2 and 3-way algorithms, we have shown that the addition of chromatographic separation information improves the results compared to the 2-way analysis of mass spectra or total ion chromatogram treated separately. Our findings show that when the chromatographic peaks are resolved (longer measurement times), 2-way methods work better than 3-way methods, whereas in the case of a more challenging measurement (more coeluted chromatograms, much faster GC-MS measurements) 3-way methods work better.

  2. Pressure and Temperature Sensors Using Two Spin Crossover Materials

    PubMed Central

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

    2016-01-01

    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. PMID:26848663

  3. 3 Ways.

    ERIC Educational Resources Information Center

    Hale, Hanna S.; And Others

    1982-01-01

    Describes three art activities for the Christmas holidays. Upper-elementary art classes create a life-size Santa's workshop decorated with paper-mache gingerbread cookies. Kindergarten children draw the king and queen of Christmas. Elementary and secondary students decorate store windows for holidays and community celebrations. (AM)

  4. A new design of trial for hypnotics comparison: a double-blind cross-over trial with patient's preference assessment and continuation of the preferred treatment.

    PubMed

    Bourin, M; Malinge, M

    1996-04-01

    1. This study compared two hypnotics administrated at comparable therapeutic dosages: triazolam (0.25 mg) and loprazolam (1 mg), were administered using an original scheme (cross-over on the first 2 nights, and continuation of the preferred treatment or new randomization). 2. Sixty-seven outpatients complaining of common insomnia participated in this study conducted by general practitioners. 3. Both drugs provided improvement in sleep quality (decreased sleep latency, increased total duration of sleep, decreased number of night awakenings), and are equally well tolerated. 4. For the first 2 nights, triazolam was evaluated to be more efficient than loprazolam (p < 0.001), and patients felt more rested the following day (p < 0.01) with the former drug. Moreover, triazolam is more frequently preferred than loprazolam by 47.7% and 29.2%, respectively, (p = 0.09). 5. No interaction was found between treatment and order of administration or specific effects and order of administration.

  5. Meiotic recombination protein Rec12: functional conservation, crossover homeostasis and early crossover/non-crossover decision

    PubMed Central

    Kan, Fengling; Davidson, Mari K.; Wahls, Wayne P.

    2011-01-01

    In fission yeast and other eukaryotes, Rec12 (Spo11) is thought to catalyze the formation of dsDNA breaks (DSBs) that initiate homologous recombination in meiosis. Rec12 is orthologous to the catalytic subunit of topoisomerase VI (Top6A). Guided by the crystal structure of Top6A, we engineered the rec12 locus to encode Rec12 proteins each with a single amino acid substitution in a conserved residue. Of 21 substitutions, 10 significantly reduced or abolished meiotic DSBs, gene conversion, crossover recombination and the faithful segregation of chromosomes. Critical residues map within the metal ion-binding pocket toprim (E179A, D229A, D231A), catalytic region 5Y-CAP (R94A, D95A, Y98F) and the DNA-binding interface (K201A, G202E, R209A, K242A). A subset of substitutions reduced DSBs but maintained crossovers, demonstrating crossover homeostasis. Furthermore, a strong separation of function mutation (R304A) suggests that the crossover/non-crossover decision is established early by a protein–protein interaction surface of Rec12. Fission yeast has multiple crossovers per bivalent, and chromosome segregation was robust above a threshold of about one crossover per bivalent, below which non-disjunction occurred. These results support structural and functional conservation among Rec12/Spo11/Top6A family members for the catalysis of DSBs, and they reveal how Rec12 regulates other features of meiotic chromosome dynamics. PMID:21030440

  6. Meiotic recombination protein Rec12: functional conservation, crossover homeostasis and early crossover/non-crossover decision.

    PubMed

    Kan, Fengling; Davidson, Mari K; Wahls, Wayne P

    2011-03-01

    In fission yeast and other eukaryotes, Rec12 (Spo11) is thought to catalyze the formation of dsDNA breaks (DSBs) that initiate homologous recombination in meiosis. Rec12 is orthologous to the catalytic subunit of topoisomerase VI (Top6A). Guided by the crystal structure of Top6A, we engineered the rec12 locus to encode Rec12 proteins each with a single amino acid substitution in a conserved residue. Of 21 substitutions, 10 significantly reduced or abolished meiotic DSBs, gene conversion, crossover recombination and the faithful segregation of chromosomes. Critical residues map within the metal ion-binding pocket toprim (E179A, D229A, D231A), catalytic region 5Y-CAP (R94A, D95A, Y98F) and the DNA-binding interface (K201A, G202E, R209A, K242A). A subset of substitutions reduced DSBs but maintained crossovers, demonstrating crossover homeostasis. Furthermore, a strong separation of function mutation (R304A) suggests that the crossover/non-crossover decision is established early by a protein-protein interaction surface of Rec12. Fission yeast has multiple crossovers per bivalent, and chromosome segregation was robust above a threshold of about one crossover per bivalent, below which non-disjunction occurred. These results support structural and functional conservation among Rec12/Spo11/Top6A family members for the catalysis of DSBs, and they reveal how Rec12 regulates other features of meiotic chromosome dynamics. PMID:21030440

  7. Hybrid spin-crossover nanostructures

    PubMed Central

    Quintero, Carlos M; Félix, Gautier; Suleimanov, Iurii; Sánchez Costa, José; Molnár, Gábor; Salmon, Lionel; Nicolazzi, William

    2014-01-01

    Summary This review reports on the recent progress in the synthesis, modelling and application of hybrid spin-crossover materials, including core–shell nanoparticles and multilayer thin films or nanopatterns. These systems combine, often in synergy, different physical properties (optical, magnetic, mechanical and electrical) of their constituents with the switching properties of spin-crossover complexes, providing access to materials with unprecedented capabilities. PMID:25551051

  8. The Impact of Oxytocin on Food Intake and Emotion Recognition in Patients with Eating Disorders: A Double Blind Single Dose Within-Subject Cross-Over Design

    PubMed Central

    Kim, Youl-Ri; Eom, Jin-Sup; Yang, Jae-Won; Kang, Jiwon; Treasure, Janet

    2015-01-01

    Background and Aim Social difficulties and problems related to eating behaviour are common features of both anorexia nervosa (AN) and bulimia nervosa (BN). The aim of this study was to examine the impact of intranasal oxytocin on consummatory behaviour and emotional recognition in patients with AN and BN in comparison to healthy controls. Materials A total of 102 women, including 35 patients with anorexia nervosa (AN), 34 patients with bulimia nervosa (BN), and 33 healthy university students of comparable age and intelligence, participated in a double-blind, single dose placebo-controlled cross-over study. A single dose of intranasal administration of oxytocin (40 IU) (or a placebo) was followed by an emotional recognition task and an apple juice drink. Food intake was then recorded for 24 hours post-test. Results Oxytocin produced no significant change in appetite in the acute or 24 hours free living settings in healthy controls, whereas there was a decrease in calorie consumption over 24 hours in patients with BN. Oxytocin produced a small increase in emotion recognition sensitivity in healthy controls and in patients with BN, In patients with AN, oxytocin had no effect on emotion recognition sensitivity or on consummatory behaviour. Conclusions The impact of oxytocin on appetite and social cognition varied between people with AN and BN. A single dose of intranasal oxytocin decreased caloric intake over 24 hours in people with BN. People with BN showed enhanced emotional sensitivity under oxytocin condition similar to healthy controls. Those effects of oxytocin were not found in patients with AN. Trial Registration ClinicalTrials.gov KCT0000716 PMID:26402337

  9. 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.

  10. Aortic arch replacement with a beating heart: a simple method using continuous 3-way perfusion.

    PubMed

    Abu-Omar, Y; Ali, J M; Colah, S; Dunning, J J

    2014-01-01

    We describe a simplified 3-way perfusion strategy that could be used in complex aortic procedures, which ensures continuous end-organ perfusion and minimizes the potential risks of cardiac, cerebral and peripheral ischaemic complications.

  11. 3-way Networks: Application of Hypergraphs for Modelling Increased Complexity in Comparative Genomics

    DOE PAGES

    Weighill, Deborah A.; Jacobson, Daniel A.

    2015-03-27

    Herein we present and develop the theory of 3-way networks, a type of hypergraph in which each edge models relationships between triplets of objects as opposed to pairs of objects as done by standard network models. We explore approaches of how to prune these 3-way networks, illustrate their utility in comparative genomics and demonstrate how they find relationships which would be missed by standard 2-way network models using a phylogenomic dataset of 211 bacterial genomes.

  12. Microelectronic superconducting crossover and coil

    DOEpatents

    Wellstood, F.C.; Kingston, J.J.; Clarke, J.

    1994-03-01

    A microelectronic component comprising a crossover is provided comprising a substrate, a first high T[sub c] superconductor thin film, a second insulating thin film comprising SrTiO[sub 3]; and a third high T[sub c] superconducting film which has strips which crossover one or more areas of the first superconductor film. An in situ method for depositing all three films on a substrate is provided which does not require annealing steps and which can be opened to the atmosphere between depositions. 13 figures.

  13. The BCS-BEC Crossover

    NASA Astrophysics Data System (ADS)

    Parish, Meera M.

    2015-09-01

    This chapter presents the crossover from the Bardeen-Cooper-Schrieffer (BCS) state of weakly correlated pairs of fermions to the Bose-Einstein condensation (BEC) of diatomic molecules in the atomic Fermi gas. Our aim is to provide a pedagogical review of the BCS-BEC crossover, with an emphasis on the basic concepts, particularly those that are not generally known or are difficult to find in the literature. We shall not attempt to give an exhaustive survey of current research in the limited space here; where possible, we will direct the reader to more extensive reviews.

  14. Dimensional crossover in semiconductor nanostructures

    NASA Astrophysics Data System (ADS)

    McDonald, Matthew P.; Chatterjee, Rusha; Si, Jixin; Jankó, Boldizsár; Kuno, Masaru

    2016-08-01

    Recent advances in semiconductor nanostructure syntheses provide unprecedented control over electronic quantum confinement and have led to extensive investigations of their size- and shape-dependent optical/electrical properties. Notably, spectroscopic measurements show that optical bandgaps of one-dimensional CdSe nanowires are substantially (approximately 100 meV) lower than their zero-dimensional counterparts for equivalent diameters spanning 5-10 nm. But what, exactly, dictates the dimensional crossover of a semiconductor's electronic structure? Here we probe the one-dimensional to zero-dimensional transition of CdSe using single nanowire/nanorod absorption spectroscopy. We find that carrier electrostatic interactions play a fundamental role in establishing dimensional crossover. Moreover, the critical length at which this transition occurs is governed by the aspect ratio-dependent interplay between carrier confinement and dielectric contrast/confinement energies.

  15. Dimensional crossover in semiconductor nanostructures

    PubMed Central

    McDonald, Matthew P.; Chatterjee, Rusha; Si, Jixin; Jankó, Boldizsár; Kuno, Masaru

    2016-01-01

    Recent advances in semiconductor nanostructure syntheses provide unprecedented control over electronic quantum confinement and have led to extensive investigations of their size- and shape-dependent optical/electrical properties. Notably, spectroscopic measurements show that optical bandgaps of one-dimensional CdSe nanowires are substantially (approximately 100 meV) lower than their zero-dimensional counterparts for equivalent diameters spanning 5–10 nm. But what, exactly, dictates the dimensional crossover of a semiconductor's electronic structure? Here we probe the one-dimensional to zero-dimensional transition of CdSe using single nanowire/nanorod absorption spectroscopy. We find that carrier electrostatic interactions play a fundamental role in establishing dimensional crossover. Moreover, the critical length at which this transition occurs is governed by the aspect ratio-dependent interplay between carrier confinement and dielectric contrast/confinement energies. PMID:27577091

  16. Dimensional crossover in semiconductor nanostructures.

    PubMed

    McDonald, Matthew P; Chatterjee, Rusha; Si, Jixin; Jankó, Boldizsár; Kuno, Masaru

    2016-01-01

    Recent advances in semiconductor nanostructure syntheses provide unprecedented control over electronic quantum confinement and have led to extensive investigations of their size- and shape-dependent optical/electrical properties. Notably, spectroscopic measurements show that optical bandgaps of one-dimensional CdSe nanowires are substantially (approximately 100 meV) lower than their zero-dimensional counterparts for equivalent diameters spanning 5-10 nm. But what, exactly, dictates the dimensional crossover of a semiconductor's electronic structure? Here we probe the one-dimensional to zero-dimensional transition of CdSe using single nanowire/nanorod absorption spectroscopy. We find that carrier electrostatic interactions play a fundamental role in establishing dimensional crossover. Moreover, the critical length at which this transition occurs is governed by the aspect ratio-dependent interplay between carrier confinement and dielectric contrast/confinement energies. PMID:27577091

  17. Crossover behavior in a communication network.

    PubMed

    Singh, Brajendra K; Gupte, Neelima

    2003-12-01

    We address the problem of message transfer in a communication network. The network consists of nodes and links, with the nodes lying on a two-dimensional lattice. Each node has connections with its nearest neighbors, whereas some special nodes, which are designated as hubs, have connections to all the sites within a certain area of influence. The degree distribution for this network is bimodal in nature and has finite variance. The distribution of travel times between two sites situated at a fixed distance on this lattice shows fat-fractal behavior as a function of hub density. If extra assortative connections are now introduced between the hubs so that each hub is connected to two or three other hubs, the distribution crosses over to power-law behavior. Crossover behavior is also seen if end-to-end short cuts are introduced between hubs whose areas of influence overlap, but this is much milder in nature. In yet another information transmission process, namely, the spread of infection on the network with assortative connections, we again observed crossover behavior of another type, viz., from one power law to another for the threshold values of disease transmission probability. Our results are relevant for the understanding of the role of network topology in information spread processes.

  18. 3D Framework DNA Origami with Layered Crossovers.

    PubMed

    Hong, Fan; Jiang, Shuoxing; Wang, Tong; Liu, Yan; Yan, Hao

    2016-10-01

    Designer DNA architectures with nanoscale geometric controls provide a programmable molecular toolbox for engineering complex nanodevices. Scaffolded DNA origami has dramatically improved our ability to design and construct DNA nanostructures with finite size and spatial addressability. Here we report a novel design strategy to engineer multilayered wireframe DNA structures by introducing crossover pairs that connect neighboring layers of DNA double helices. These layered crossovers (LX) allow the scaffold or helper strands to travel through different layers and can control the relative orientation of DNA helices in neighboring layers. Using this design strategy, we successfully constructed four versions of two-layer parallelogram structures with well-defined interlayer angles, a three-layer structure with triangular cavities, and a 9- and 15-layer square lattices. This strategy provides a general route to engineer 3D framework DNA nanostructures with controlled cavities and opportunities to design host-guest networks analogs to those produced with metal organic frameworks.

  19. 3D Framework DNA Origami with Layered Crossovers.

    PubMed

    Hong, Fan; Jiang, Shuoxing; Wang, Tong; Liu, Yan; Yan, Hao

    2016-10-01

    Designer DNA architectures with nanoscale geometric controls provide a programmable molecular toolbox for engineering complex nanodevices. Scaffolded DNA origami has dramatically improved our ability to design and construct DNA nanostructures with finite size and spatial addressability. Here we report a novel design strategy to engineer multilayered wireframe DNA structures by introducing crossover pairs that connect neighboring layers of DNA double helices. These layered crossovers (LX) allow the scaffold or helper strands to travel through different layers and can control the relative orientation of DNA helices in neighboring layers. Using this design strategy, we successfully constructed four versions of two-layer parallelogram structures with well-defined interlayer angles, a three-layer structure with triangular cavities, and a 9- and 15-layer square lattices. This strategy provides a general route to engineer 3D framework DNA nanostructures with controlled cavities and opportunities to design host-guest networks analogs to those produced with metal organic frameworks. PMID:27628457

  20. An Analysis of Semantic Aware Crossover

    NASA Astrophysics Data System (ADS)

    Uy, Nguyen Quang; Hoai, Nguyen Xuan; O'Neill, Michael; McKay, Bob; Galván-López, Edgar

    It is well-known that the crossover operator plays an important role in Genetic Programming (GP). In Standard Crossover (SC), semantics are not used to guide the selection of the crossover points, which are generated randomly. This lack of semantic information is the main cause of destructive effects from SC (e.g., children having lower fitness than their parents). Recently, we proposed a new semantic based crossover known GP called Semantic Aware Crossover (SAC) [25]. We show that SAC outperforms SC in solving a class of real-value symbolic regression problems. We clarify the effect of SAC on GP search in increasing the semantic diversity of the population, thus helping to reduce the destructive effects of crossover in GP.

  1. Assessment of bitter taste of pharmaceuticals with multisensor system employing 3 way PLS regression.

    PubMed

    Rudnitskaya, Alisa; Kirsanov, Dmitry; Blinova, Yulia; Legin, Evgeny; Seleznev, Boris; Clapham, David; Ives, Robert S; Saunders, Kenneth A; Legin, Andrey

    2013-04-01

    The application of the potentiometric multisensor system (electronic tongue, ET) for quantification of the bitter taste of structurally diverse active pharmaceutical ingredients (API) is reported. The measurements were performed using a set of bitter substances that had been assessed by a professional human sensory panel and the in vivo rat brief access taste aversion (BATA) model to produce bitterness intensity scores for each substance at different concentrations. The set consisted of eight substances, both inorganic and organic - azelastine, caffeine, chlorhexidine, potassium nitrate, naratriptan, paracetamol, quinine, and sumatriptan. With the aim of enhancing the response of the sensors to the studied APIs, measurements were carried out at different pH levels ranging from 2 to 10, thus promoting ionization of the compounds. This experiment yielded a 3 way data array (samples×sensors×pH levels) from which 3wayPLS regression models were constructed with both human panel and rat model reference data. These models revealed that artificial assessment of bitter taste with ET in the chosen set of API's is possible with average relative errors of 16% in terms of human panel bitterness score and 25% in terms of inhibition values from in vivo rat model data. Furthermore, these 3wayPLS models were applied for prediction of the bitterness in blind test samples of a further set of API's. The results of the prediction were compared with the inhibition values obtained from the in vivo rat model. PMID:23498685

  2. Crossover in the Efimov spectrum

    SciTech Connect

    Pricoupenko, Ludovic

    2010-10-15

    A filtering method is introduced for solving the zero-range three-boson problem. This scheme permits solving the original Skorniakov Ter-Martirosian integral equation for an arbitrary large ultraviolet cutoff and avoiding the Thomas collapse of the three particles. The method is applied to a more general zero-range model including a finite-background two-body scattering length and the effective range. A crossover in the Efimov spectrum is found in such systems and a specific regime emerges where Efimov states are long-lived.

  3. 24 CFR 3285.701 - Electrical crossovers.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 24 Housing and Urban Development 5 2010-04-01 2010-04-01 false Electrical crossovers. 3285.701... URBAN DEVELOPMENT MODEL MANUFACTURED HOME INSTALLATION STANDARDS Electrical Systems and Equipment § 3285.701 Electrical crossovers. Multi-section homes with electrical wiring in more than one section...

  4. 24 CFR 3285.701 - Electrical crossovers.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 24 Housing and Urban Development 5 2011-04-01 2011-04-01 false Electrical crossovers. 3285.701... URBAN DEVELOPMENT MODEL MANUFACTURED HOME INSTALLATION STANDARDS Electrical Systems and Equipment § 3285.701 Electrical crossovers. Multi-section homes with electrical wiring in more than one section...

  5. 24 CFR 3285.701 - Electrical crossovers.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... URBAN DEVELOPMENT MODEL MANUFACTURED HOME INSTALLATION STANDARDS Electrical Systems and Equipment § 3285.701 Electrical crossovers. Multi-section homes with electrical wiring in more than one section require... 24 Housing and Urban Development 5 2013-04-01 2013-04-01 false Electrical crossovers....

  6. 24 CFR 3285.701 - Electrical crossovers.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... URBAN DEVELOPMENT MODEL MANUFACTURED HOME INSTALLATION STANDARDS Electrical Systems and Equipment § 3285.701 Electrical crossovers. Multi-section homes with electrical wiring in more than one section require... 24 Housing and Urban Development 5 2014-04-01 2014-04-01 false Electrical crossovers....

  7. 24 CFR 3285.701 - Electrical crossovers.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... URBAN DEVELOPMENT MODEL MANUFACTURED HOME INSTALLATION STANDARDS Electrical Systems and Equipment § 3285.701 Electrical crossovers. Multi-section homes with electrical wiring in more than one section require... 24 Housing and Urban Development 5 2012-04-01 2012-04-01 false Electrical crossovers....

  8. Zebrafish Caudal Fin Angiogenesis Assay—Advanced Quantitative Assessment Including 3-Way Correlative Microscopy

    PubMed Central

    Correa Shokiche, Carlos; Schaad, Laura; Triet, Ramona; Jazwinska, Anna; Tschanz, Stefan A.; Djonov, Valentin

    2016-01-01

    Background Researchers evaluating angiomodulating compounds as a part of scientific projects or pre-clinical studies are often confronted with limitations of applied animal models. The rough and insufficient early-stage compound assessment without reliable quantification of the vascular response counts, at least partially, to the low transition rate to clinics. Objective To establish an advanced, rapid and cost-effective angiogenesis assay for the precise and sensitive assessment of angiomodulating compounds using zebrafish caudal fin regeneration. It should provide information regarding the angiogenic mechanisms involved and should include qualitative and quantitative data of drug effects in a non-biased and time-efficient way. Approach & Results Basic vascular parameters (total regenerated area, vascular projection area, contour length, vessel area density) were extracted from in vivo fluorescence microscopy images using a stereological approach. Skeletonization of the vasculature by our custom-made software Skelios provided additional parameters including “graph energy” and “distance to farthest node”. The latter gave important insights into the complexity, connectivity and maturation status of the regenerating vascular network. The employment of a reference point (vascular parameters prior amputation) is unique for the model and crucial for a proper assessment. Additionally, the assay provides exceptional possibilities for correlative microscopy by combining in vivo-imaging and morphological investigation of the area of interest. The 3-way correlative microscopy links the dynamic changes in vivo with their structural substrate at the subcellular level. Conclusions The improved zebrafish fin regeneration model with advanced quantitative analysis and optional 3-way correlative morphology is a promising in vivo angiogenesis assay, well-suitable for basic research and preclinical investigations. PMID:26950851

  9. Topoisomerase II Mediates Meiotic Crossover Interference

    PubMed Central

    Zhang, Liangran; Wang, Shunxin; Yin, Shen; Hong, Soogil; Kim, Keun P.; Kleckner, Nancy

    2014-01-01

    Summary Spatial patterning is a ubiquitous feature of biological systems. Meiotic crossovers provide an interesting example, defined by the classical phenomenon of crossover interference. Here, analysis of crossover patterns in budding yeast identifies a molecular pathway for interference. Topoisomerase II (Topo II) plays a central role, thus identifying a new function for this critical molecule. SUMOylation [of TopoII and axis component Red1] and ubiquitin-mediated removal of SUMOylated proteins are also required. These and other findings support the hypothesis that crossover interference involves accumulation, relief and redistribution of mechanical stress along the protein/DNA meshwork of meiotic chromosome axes, with TopoII required to adjust spatial relationships among DNA segments. PMID:25043020

  10. Spin crossover properties of enantiomers, co-enantiomers, racemates, and co-racemates.

    PubMed

    Qin, Long-Fang; Pang, Chun-Yan; Han, Wang-Kang; Zhang, Feng-Li; Tian, Lei; Gu, Zhi-Guo; Ren, Xuehong; Li, Zaijun

    2016-04-25

    Through multi-component self-assembly of chiral phenylethylamine, 1-alkyl-2-imidazolecarboxaldehyde and iron(ii) ions, two couples of enantiomeric iron(ii) complexes , , and with the formula of fac-Λ or Δ-[Fe(L)3](2+)(L = R or S-1-phenyl-N-(1-alkyl-1H-imidazol-2-ylmethylene)ethanamine) have been designed and synthesized as building blocks. Further binary cocrystallization of the prefabricated enantiomers enabled us to construct spin crossover co-enantiomers and , racemates and , and co-racemate . Compared with in a high spin state and with spin crossover at 291 K, the co-enantiomers exhibited gradual spin crossover at a higher temperature of 301 K, and the racemic alloys showed hysteresis loops induced by desolvation above room temperature. It was demonstrated that molecular chirality could be used effectively for stereochemical engineering of spin crossover materials. In addition, crystal packing, intramolecular π-π stacking, intermolecular C-Hπ interactions and solvent effects were elucidated to be responsible for the distinct spin crossover properties. This collective structural and magnetic study not only enriched the spin crossover library, but also provided a full comparison of optically pure, homochiral, and racemic materials with similar molecular structures. PMID:27021212

  11. Spin-crossover molecule based thermoelectric junction

    SciTech Connect

    Ghosh, Dibyajyoti; Parida, Prakash; Pati, Swapan K.

    2015-05-11

    Using ab-initio numerical methods, we explore the spin-dependent transport and thermoelectric properties of a spin-crossover molecule (i.e., iron complex of 2-(1H-pyrazol-1-yl)-6-(1H-tetrazole-5-yl)pyridine) based nano-junction. We demonstrate a large magnetoresistance, efficient conductance-switching, and spin-filter activity in this molecule-based two-terminal device. The spin-crossover process also modulates the thermoelectric entities. It can efficiently switch the magnitude as well as spin-polarization of the thermocurrent. We find that thermocurrent is changed by ∼4 orders of magnitude upon spin-crossover. Moreover, it also substantially affects the thermopower and consequently, the device shows extremely efficient spin-crossover magnetothermopower generation. Furthermore, by tuning the chemical potential of electrodes into a certain range, a pure spin-thermopower can be achieved for the high-spin state. Finally, the reasonably large values of figure-of-merit in the presence and absence of phonon demonstrate a large heat-to-voltage conversion efficiency of the device. We believe that our study will pave an alternative way of tuning the transport and thermoelectric properties through the spin-crossover process and can have potential applications in generation of spin-dependent current, information storage, and processing.

  12. Multiferroic crossover in perovskite oxides

    NASA Astrophysics Data System (ADS)

    Weston, L.; Cui, X. Y.; Ringer, S. P.; Stampfl, C.

    2016-04-01

    drives the ferroelectric state (Kv). The recovery of the lattice instability for high-spin d5-d7 and d8 cations is due to (i) a reduction in K0 due to a significant volume increase arising from population of the σ -bonded axial d eg orbitals, and (ii) an increase in the Kv contribution arising from increased p -d hybridization; our calculations suggest that the former mechanism is dominant. Surprisingly, we are able to show that, in some cases unpaired electron spins actually drive ferroelectricity, rather than inhibit it, which represents a shift in the understanding of how ferroelectricity and magnetism interact in perovskite oxides. It follows, that for the case of BiCoO3, the Co3 + ion plays a major role in the ferroelectric lattice instability. Importantly, the ferroelectric polarization is greatly enhanced when the Co3 + ion is in the high-spin state, when compared to the nonmagnetic, low-spin state, and a large coupling of the electric and magnetic polarization is present. Generally, for d5-d7 B cations in A B O3 perovskites, an inherent and remarkably strong magnetoelectric coupling exists via the multiferroic crossover effect, whereby switching the spin state strongly affects the ferroelectric polarization and, potentially, manipulation of the polarization with an externally applied electric field could induce a spin-state transition. This novel effect is demonstrated for BiCoO3, for which the ground spin state is switched by reducing the internal ferroelectric polarization. These results provide a deeper insight into perovskite ferroelectrics and multiferroics.

  13. 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…

  14. Cedarwood: cross-over pressure research

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A series of experiments were conducted to determine the cross-over pressure for cedarwood oil in carbon dioxide. A closed stirrer reactor with an in-line loop connected to the injector of a GC was used to measure the concentration of cedarwood oil in the carbon dioxide. Both neat cedarwood oil as ...

  15. Laughing Lessons: 149 2/3 Ways To Make Teaching and Learning Fun.

    ERIC Educational Resources Information Center

    Burgess, Ron

    This book presents classroom-tested ideas to help teachers make teaching and learning more enjoyable, noting that humor can be a positive force in teaching, learning, and health. The book is designed to: help teachers see the importance of a pleasant, good-humored environment; convince teachers that laughter can be an essential element in…

  16. Self-assembly of fully addressable DNA nanostructures from double crossover tiles.

    PubMed

    Wang, Wen; Lin, Tong; Zhang, Suoyu; Bai, Tanxi; Mi, Yongli; Wei, Bryan

    2016-09-19

    DNA origami and single-stranded tile (SST) are two proven approaches to self-assemble finite-size complex DNA nanostructures. The construction elements appeared in structures from these two methods can also be found in multi-stranded DNA tiles such as double crossover tiles. Here we report the design and observation of four types of finite-size lattices with four different double crossover tiles, respectively, which, we believe, in terms of both complexity and robustness, will be rival to DNA origami and SST structures.

  17. Self-assembly of fully addressable DNA nanostructures from double crossover tiles

    PubMed Central

    Wang, Wen; Lin, Tong; Zhang, Suoyu; Bai, Tanxi; Mi, Yongli; Wei, Bryan

    2016-01-01

    DNA origami and single-stranded tile (SST) are two proven approaches to self-assemble finite-size complex DNA nanostructures. The construction elements appeared in structures from these two methods can also be found in multi-stranded DNA tiles such as double crossover tiles. Here we report the design and observation of four types of finite-size lattices with four different double crossover tiles, respectively, which, we believe, in terms of both complexity and robustness, will be rival to DNA origami and SST structures. PMID:27484479

  18. Crossover from quantum to classical transport

    NASA Astrophysics Data System (ADS)

    Morr, Dirk K.

    2016-01-01

    Understanding the crossover from quantum to classical transport has become of fundamental importance not only for technological applications due to the creation of sub-10-nm transistors - an important building block of our modern life - but also for elucidating the role played by quantum mechanics in the evolutionary fitness of biological complexes. This article provides a basic introduction into the nature of charge and energy transport in the quantum and classical regimes. It discusses the characteristic transport properties in both limits and demonstrates how they can be connected through the loss of quantum mechanical coherence. The salient features of the crossover physics are identified, and their importance in opening new transport regimes and in understanding efficient and robust energy transport in biological complexes are demonstrated.

  19. Universal Entanglement Crossover of Coupled Quantum Wires

    NASA Astrophysics Data System (ADS)

    Vasseur, Romain; Jacobsen, Jesper Lykke; 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. We argue in this Letter that the correct universal scaling form of the entanglement entropy S (for an arbitrary interval of length L containing the impurity) is ∂S/∂ ln L=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.

  20. JavaGenes: Evolving Graphs with Crossover

    NASA Technical Reports Server (NTRS)

    Globus, Al; Atsatt, Sean; Lawton, John; Wipke, Todd

    2000-01-01

    Genetic algorithms usually use string or tree representations. We have developed a novel crossover operator for a directed and undirected graph representation, and used this operator to evolve molecules and circuits. Unlike strings or trees, a single point in the representation cannot divide every possible graph into two parts, because graphs may contain cycles. Thus, the crossover operator is non-trivial. A steady-state, tournament selection genetic algorithm code (JavaGenes) was written to implement and test the graph crossover operator. All runs were executed by cycle-scavagging on networked workstations using the Condor batch processing system. The JavaGenes code has evolved pharmaceutical drug molecules and simple digital circuits. Results to date suggest that JavaGenes can evolve moderate sized drug molecules and very small circuits in reasonable time. The algorithm has greater difficulty with somewhat larger circuits, suggesting that directed graphs (circuits) are more difficult to evolve than undirected graphs (molecules), although necessary differences in the crossover operator may also explain the results. In principle, JavaGenes should be able to evolve other graph-representable systems, such as transportation networks, metabolic pathways, and computer networks. However, large graphs evolve significantly slower than smaller graphs, presumably because the space-of-all-graphs explodes combinatorially with graph size. Since the representation strongly affects genetic algorithm performance, adding graphs to the evolutionary programmer's bag-of-tricks should be beneficial. Also, since graph evolution operates directly on the phenotype, the genotype-phenotype translation step, common in genetic algorithm work, is eliminated.

  1. Quantum-classical crossover in electrodynamics

    SciTech Connect

    Polonyi, Janos

    2006-09-15

    A classical field theory is proposed for the electric current and the electromagnetic field interpolating between microscopic and macroscopic domains. It represents a generalization of the density functional for the dynamics of the current and the electromagnetic field in the quantum side of the crossover and reproduces standard classical electrodynamics on the other side. The effective action derived in the closed time path formalism and the equations of motion follow from the variational principle. The polarization of the Dirac-sea can be taken into account in the quadratic approximation of the action by the introduction of the deplacement field strengths as in conventional classical electrodynamics. Decoherence appears naturally as a simple one-loop effect in this formalism. It is argued that the radiation time arrow is generated from the quantum boundary conditions in time by decoherence at the quantum-classical crossover and the Abraham-Lorentz force arises from the accelerating charge or from other charges in the macroscopic or the microscopic side, respectively. The functional form of the quantum renormalization group, the generalization of the renormalization group method for the density matrix, is proposed to follow the scale dependence through the quantum-classical crossover in a systematical manner.

  2. Dynamical Landau theory of the glass crossover

    NASA Astrophysics Data System (ADS)

    Rizzo, Tommaso

    2016-07-01

    I introduce a dynamical field theory to describe the glassy behavior in supercooled liquids. The mean-field approximation of the theory predicts a dynamical arrest transition, as in the ideal mode-coupling theory and mean-field discontinuous spin-glass models. Instead, beyond the mean-field approximation, the theory predicts that the transition is avoided and transformed into a crossover, as observed in experiments and simulations. To go beyond mean-field, a standard perturbative loop expansion is performed at first. Approaching the ideal critical point this expansion is divergent at all orders and I show that the leading divergent term at any given order is the same as a dynamical stochastic equation, called stochastic-beta relaxation (SBR) in Europhys. Lett. 106, 56003 (2014), 10.1209/0295-5075/106/56003. At variance with the original theory, SBR can be studied beyond mean-field directly, without the need to resort to a perturbative expansion. Thus it provides a qualitative and quantitative description of the dynamical crossover. For consistency reasons, it is important to establish the connection between the dynamical field theory and SBR beyond perturbation theory. This can be done with the help of a stronger result: the dynamical field theory is exactly equivalent to a theory with quenched disorder. Qualitatively, the nonperturbative mechanism leading to the crossover is therefore the same as the mechanism of SBR. Quantitatively, SBR is equivalent to making the mean-field approximation once the quenched disorder has been generated.

  3. 3-Way characterization of soils by Procrustes rotation, matrix-augmented principal components analysis and parallel factor analysis.

    PubMed

    Andrade, J M; Kubista, M; Carlosena, A; Prada, D

    2007-11-01

    Three different approaches for 3-way analyses, namely, Procrustes rotation, parallel factor analysis (PARAFAC) and matrix-augmented principal component analysis, have been compared considering a four-seasons study on soil pollution. Each sampling season comprised 92 roadsoil samples and 12 analytical variables (heavy metals, loss on ignition, pH and humidity). Results show that the three chemometric techniques lead to essentially the same conclusions. Hence, Procrustes rotation, a mathematical technique scarcely applied in analytical chemistry, revealed as a useful tool for 3-way data analysis with potential advantages, including its conceptual simplicity and straightforward interpretation of the results. A novel application of the consensus vectors allowed definition of "consensus scores" so that visualization of the samples and temporal patterns can be made. Results also suggested that the trilinearity assumption imbedded in PARAFAC is essentially fulfilled when studying the temporal evolution of an environmental system where no new pollution sources appear during the course of the study. PMID:17950053

  4. Geosat crossover analysis in the tropical Pacific. Part 1: Constrained sinusoidal crossover adjustment

    NASA Technical Reports Server (NTRS)

    Tai, Chang-Kou

    1988-01-01

    A new method (constrained sinusoidal crossover adjustment) for removing the orbit error in satellite altimetry is tested (using crossovers accumulated in the first 91 days of the Geosat non-repeat era in the tropical Pacific) and found to have excellent qualities. Two features distinguish the new method from the conventional bias-and-tilt crossover adjustment. First, a sine wave (with wavelength equaling the circumference of the Earth) is used to represent the orbit error for each satellite revolution, instead of the bias-and-tilt (and curvature, if necessary) approach for each segment of the satellite ground track. Secondly, the indeterminacy of the adjustment process is removed by a simple constraint minimizing the amplitudes of the sine waves, rather than by fixing selected tracks. Overall the new method is more accurate, more efficient, and much less cumbersome than the old. The idea of restricting the crossover adjustment to crossovers between tracks that are less than certain days apart in order to preserve the large-scale long-term oceanic variability is also tested with inconclusive results because the orbit error was unusually nonstationary in the initial 91 days of the GEOSAT mission.

  5. A new crossover operator in genetic programming for object classification.

    PubMed

    Zhang, Mengjie; Gao, Xiaoying; Lou, Weijun

    2007-10-01

    The crossover operator has been considered "the centre of the storm" in genetic programming (GP). However, many existing GP approaches to object recognition suggest that the standard GP crossover is not sufficiently powerful in producing good child programs due to the totally random choice of the crossover points. To deal with this problem, this paper introduces an approach with a new crossover operator in GP for object recognition, particularly object classification. In this approach, a local hill-climbing search is used in constructing good building blocks, a weight called looseness is introduced to identify the good building blocks in individual programs, and the looseness values are used as heuristics in choosing appropriate crossover points to preserve good building blocks. This approach is examined and compared with the standard crossover operator and the headless chicken crossover (HCC) method on a sequence of object classification problems. The results suggest that this approach outperforms the HCC, the standard crossover, and the standard crossover operator with hill climbing on all of these problems in terms of the classification accuracy. Although this approach spends a bit longer time than the standard crossover operator, it significantly improves the system efficiency over the HCC method. PMID:17926713

  6. Photoinduced antiferromagnetic to ferromagnetic crossover in organic systems.

    PubMed

    Shil, Suranjan; Misra, Anirban

    2010-02-01

    Magnetization reversal is important for different technological applications. Photoinduced magnetization reversal is easier to implement than conventional reversal methods. Here, we theoretically design and investigate the photomagnetic property of azobenzene based diradical systems, where trans isomers convert into corresponding cis forms upon irradiation with light of appropriate wavelength. The coupling constant values have been estimated using the broken symmetry approach in the density functional theory framework. In each case, the trans isomer is found to be antiferromagnetic, while the cis form is ferromagnetic in nature. Therefore, photoinduced magnetic crossover from antiferromagnetic to ferromagnetic regime would be observed. This is a new observation in case of the systems of organic origin. Importance of such systems for photomagnetic switches, sensors, high density data storage, spin valves, and semiconductor spintronic materials have also been discussed with support from density of state analysis, singly occupied molecular orbital-singly occupied molecular orbital energy gaps and spin density plots.

  7. Metal ion sensing solution containing double crossover DNA

    NASA Astrophysics Data System (ADS)

    Park, Byeongho; Dugasani, Sreekantha R.; Cho, Youngho; Oh, Juyeong; Kim, Chulki; Seo, Min Ah; Lee, Taikjin; Jhon, Young Miin; Woo, Deok Ha; Lee, Seok; Jun, Seong Chan; Park, Sung Ha; Kim, Jae Hun

    2015-07-01

    The current study describes metal ion sensing with double crossover DNAs (DX1 and DX2), artificially designed as a platform of doping. The sample for sensing is prepared by a facile annealing method to grow the DXs lattice on a silicon/silicon oxide. Adding and incubating metal ion solution with the sensor substrate into the micro-tube lead the optical property change. Photoluminescence (PL) is employed for detecting the concentration of metal ion in the specimen. We investigated PL emission for sensor application with the divalent copper. In the range from 400 to 650 nm, the PL features of samples provide significantly different peak positions with excitation and emission detection. Metal ions contribute to modify the optical characteristics of DX with structural and functional change, which results from the intercalation of them into hydrogen bonding positioned at the center of double helix. The PL intensity is decreased gradually after doping copper ion in the DX tile on the substrate.

  8. Topological crossovers near a quantum critical point

    NASA Astrophysics Data System (ADS)

    Khodel, V. A.; Clark, J. W.; Zverev, M. V.

    2011-09-01

    We study the temperature evolution of the single-particle spectrum ɛ-( p) and quasiparticle momentum distribution n( p) of homogeneous strongly correlated Fermi systems beyond a point where the necessary condition for stability of the Landau state is violated, and the Fermi surface becomes multi-connected by virtue of a topological crossover. Attention is focused on the different non-Fermi-liquid temperature regimes experienced by a phase exhibiting a single additional hole pocket compared with the conventional Landau state. A critical experiment is proposed to elucidate the origin of NFL behavior in dense films of liquid 3He.

  9. Shocks generate crossover behavior in lattice avalanches.

    PubMed

    Burridge, James

    2013-11-22

    A spatial avalanche model is introduced, in which avalanches increase stability in the regions where they occur. Instability is driven globally by a driving process that contains shocks. The system is typically subcritical, but the shocks occasionally lift it into a near- or supercritical state from which it rapidly retreats due to large avalanches. These shocks leave behind a signature-a distinct power-law crossover in the avalanche size distribution. The model is inspired by landslide field data, but the principles may be applied to any system that experiences stabilizing failures, possesses a critical point, and is subject to an ongoing process of destabilization that includes occasional dramatic destabilizing events.

  10. A quantum genetic algorithm with quantum crossover and mutation operations

    NASA Astrophysics Data System (ADS)

    SaiToh, Akira; Rahimi, Robabeh; Nakahara, Mikio

    2013-11-01

    In the context of evolutionary quantum computing in the literal meaning, a quantum crossover operation has not been introduced so far. Here, we introduce a novel quantum genetic algorithm that has a quantum crossover procedure performing crossovers among all chromosomes in parallel for each generation. A complexity analysis shows that a quadratic speedup is achieved over its classical counterpart in the dominant factor of the run time to handle each generation.

  11. Comparing the weathering patterns of six oils using 3-way generalized Procrustes rotation and matrix-augmentation principal components.

    PubMed

    Fernández-Varela, R; Andrade, J M; Muniategui, S; Prada, D

    2010-12-17

    A case study is presented in which advanced chemical fingerprinting and data interpretation techniques are used to characterize and compare the weathering processes of six oil spillages made under controlled conditions (including the heavy oil released after the Prestige tanker sunk off the Galician coast-NW Spain on 2002). A tiered analytical approach using gas chromatography-flame ionization detection (GC-FID) and gas chromatography-mass spectrometry (GC-MS) was applied along with two different approaches for 3-way analyses; namely, generalized Procrustes rotation, and matrix-augmented principal components analysis. Results showed that the two 3-way chemometric techniques leaded to essentially the same conclusions when analyzing three sets of compounds fingerprinting the spilled hydrocarbons (aliphatic hydrocarbons, polycyclic aromatic hydrocarbons (PAHs) and a set of diagnostic ratios). A steady evolution on the weathering of the oils was observed with both techniques, but for the diagnostic ratios. The variables involved on the weathering were the lightest aliphatic hydrocarbons and a general combination of the PAHs, which differentiated mostly among the light and the heavy products (fuel oils).

  12. 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).

  13. Arabidopsis meiotic crossover hotspots overlap with H2A.Z nucleosomes at gene promoters

    PubMed Central

    Choi, Kyuha; Zhao, Xiaohui; Kelly, Krystyna A.; Venn, Oliver; Higgins, James D.; Yelina, Nataliya E.; Hardcastle, Thomas J.; Ziolkowski, Piotr A.; Copenhaver, Gregory P.; Franklin, F. Chris H.; McVean, Gil; Henderson, Ian R.

    2013-01-01

    PRDM9 directs human meiotic crossover hotspots to intergenic sequence motifs, whereas budding yeast hotspots overlap low nucleosome density regions in gene promoters. To investigate hotspots in plants, which lack PRDM9, we used coalescent analysis of Arabidopsis genetic variation. Crossovers increase towards gene promoters and terminators, and hotspots are associated with active chromatin modifications, including H2A.Z, histone H3K4me3, low nucleosome density and low DNA methylation. Hotspot-enriched A-rich and CTT-repeat DNA motifs occur upstream and downstream of transcriptional start respectively. Crossovers are asymmetric around promoters and highest over CTT-motifs and H2A.Z-nucleosomes. Pollen-typing, segregation and cytogenetic analysis show decreased crossovers in the arp6 H2A.Z deposition mutant, at multiple scales. During meiosis H2A.Z and DMC1/RAD51 recombinases form overlapping chromosomal foci. As arp6 reduces DMC1/RAD51 foci, H2A.Z may promote formation or processing of meiotic DNA double-strand breaks. We propose that gene chromatin ancestrally designates hotspots within eukaryotes and PRDM9 is a derived state within vertebrates. PMID:24056716

  14. 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.

  15. Aspartame ingestion and headaches: a randomized crossover trial.

    PubMed

    Van den Eeden, S K; Koepsell, T D; Longstreth, W T; van Belle, G; Daling, J R; McKnight, B

    1994-10-01

    To examine whether ingestion of aspartame is associated with headaches, we conducted a double-blind crossover study using volunteers with self-identified headaches after using aspartame. Of the 32 subjects randomized to receive aspartame (approximately 30 mg/kg/d) and placebo in a two-treatment, four-period crossover design, 18 completed the full protocol, seven completed part of the protocol before withdrawing due to adverse effects, three withdrew for other reasons, two were lost to follow-up, one was withdrawn due to noncompliance, and one withdrew and gave no reason. Each experimental period was 7 days long. Subjects reported headaches on 33% of the days during aspartame treatment, compared with 24% on placebo treatment (p = 0.04). Subjects who were "very sure" prior to the study that aspartame triggered some of their headaches reported larger treatment differences (aspartame = 0.37 headache-days, placebo = 0.18 headache-days; p < 0.001) than subjects who were "somewhat sure" (aspartame = 0.29 headache-days, placebo = 0.22 headache-days; p = 0.51) or "not sure" (aspartame = 0.33 headache-days, placebo = 0.39 headache-days; p = 0.51). There was no significant treatment difference in the length or intensity of headaches or in the occurrence of side effects associated with the headaches. This experiment provides evidence that, among individuals with self-reported headaches after ingestion of aspartame, a subset of this group report more headaches when tested under controlled conditions. It appears that some people are particularly susceptible to headaches caused by aspartame and may want to limit their consumption.

  16. Crossover ensembles of random matrices and skew-orthogonal polynomials

    SciTech Connect

    Kumar, Santosh; Pandey, Akhilesh

    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 give 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.

  17. 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.

  18. Extended precedence preservative crossover for job shop scheduling problems

    NASA Astrophysics Data System (ADS)

    Ong, Chung Sin; Moin, Noor Hasnah; Omar, Mohd

    2013-04-01

    Job shop scheduling problems (JSSP) is one of difficult combinatorial scheduling problems. A wide range of genetic algorithms based on the two parents crossover have been applied to solve the problem but multi parents (more than two parents) crossover in solving the JSSP is still lacking. This paper proposes the extended precedence preservative crossover (EPPX) which uses multi parents for recombination in the genetic algorithms. EPPX is a variation of the precedence preservative crossover (PPX) which is one of the crossovers that perform well to find the solutions for the JSSP. EPPX is based on a vector to determine the gene selected in recombination for the next generation. Legalization of children (offspring) can be eliminated due to the JSSP representation encoded by using permutation with repetition that guarantees the feasibility of chromosomes. The simulations are performed on a set of benchmarks from the literatures and the results are compared to ensure the sustainability of multi parents recombination in solving the JSSP.

  19. A randomized crossover study of web-based media literacy to prevent smoking.

    PubMed

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

    2016-02-01

    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 program based on health behavior theory and implemented using a two-group two-period crossover design. Students were randomly assigned by classroom to receive media literacy or control interventions in different sequences. They were assessed three times, at baseline (T0), an initial follow-up after the first intervention (T1) and a second follow-up after the second intervention (T2). Crossover analysis using analysis of variance demonstrated significant intervention coefficients, indicating that the SML condition was superior to control for the primary outcome of total SML (F = 11.99; P < 0.001) and for seven of the nine individual SML items. Results were consistent in sensitivity analyses conducted using non-parametric methods. There were changes in some exploratory theory-based outcomes including attitudes and normative beliefs but not others. In conclusion, while strength of the design of this study supports and extends prior findings around effectiveness of SML programs, influences on theory-based mediators of smoking should be further explored. PMID:26675176

  20. A randomized crossover study of web-based media literacy to prevent smoking.

    PubMed

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

    2016-02-01

    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 program based on health behavior theory and implemented using a two-group two-period crossover design. Students were randomly assigned by classroom to receive media literacy or control interventions in different sequences. They were assessed three times, at baseline (T0), an initial follow-up after the first intervention (T1) and a second follow-up after the second intervention (T2). Crossover analysis using analysis of variance demonstrated significant intervention coefficients, indicating that the SML condition was superior to control for the primary outcome of total SML (F = 11.99; P < 0.001) and for seven of the nine individual SML items. Results were consistent in sensitivity analyses conducted using non-parametric methods. There were changes in some exploratory theory-based outcomes including attitudes and normative beliefs but not others. In conclusion, while strength of the design of this study supports and extends prior findings around effectiveness of SML programs, influences on theory-based mediators of smoking should be further explored.

  1. Lattice thermal conductivity crossovers in semiconductor nanowires.

    PubMed

    Mingo, N; Broido, D A

    2004-12-10

    For binary compound semiconductor nanowires, we find a striking relationship between the nanowire's thermal conductivity kappa(nwire), the bulk material's thermal conductivity kappa(bulk), and the mass ratio of the material's constituent atoms, r, as kappa(bulk)/kappa(nwire) (alpha) (1+1/r)(-3/2). A significant consequence is the presence of crossovers in which a material with higher bulk thermal conductivity than the rest is no longer the best nanowire thermal conductor. We show that this behavior stems from a change in the dominant phonon scattering mechanism with decreasing nanowire size. The results have important implications for nanoscale heat dissipation, thermoelectricity, and thermal conductivity of nanocomposites. PMID:15697834

  2. Fuel cell membranes and crossover prevention

    DOEpatents

    Masel, Richard I.; York, Cynthia A.; Waszczuk, Piotr; Wieckowski, Andrzej

    2009-08-04

    A membrane electrode assembly for use with a direct organic fuel cell containing a formic acid fuel includes a solid polymer electrolyte having first and second surfaces, an anode on the first surface and a cathode on the second surface and electrically linked to the anode. The solid polymer electrolyte has a thickness t:.gtoreq..times..times..times..times. ##EQU00001## where C.sub.f is the formic acid fuel concentration over the anode, D.sub.f is the effective diffusivity of the fuel in the solid polymer electrolyte, K.sub.f is the equilibrium constant for partition coefficient for the fuel into the solid polymer electrolyte membrane, I is Faraday's constant n.sub.f is the number of electrons released when 1 molecule of the fuel is oxidized, and j.sub.f.sup.c is an empirically determined crossover rate of fuel above which the fuel cell does not operate.

  3. Neutrino dynamics below the electroweak crossover

    NASA Astrophysics Data System (ADS)

    Ghiglieri, J.; Laine, M.

    2016-07-01

    We estimate the thermal masses and damping rates of active (m < eV) and sterile (M ~ GeV) neutrinos with thermal momenta k~ 3T at temperatures below the electroweak crossover (5 GeV < T < 160 GeV) . These quantities fix the equilibration or ``washout'' rates of Standard Model lepton number densities. Sterile neutrinos interact via direct scatterings mediated by Yukawa couplings, and via their overlap with active neutrinos. Including all leading-order reactions we find that the washout rate generally exceeds the Hubble rate for 5 GeV < T < 30 GeV . Therefore it is challenging to generate a large lepton asymmetry facilitating dark matter computations operating at T < 5 GeV, whereas the generation of a baryon asymmetry at T > 130 GeV remains an option. Our differential rates are tabulated in a form suitable for studies of specific scenarios with given neutrino Yukawa matrices.

  4. Nonequilibrium spin crossover in copper phthalocyanine

    NASA Astrophysics Data System (ADS)

    Siegert, Benjamin; Donarini, Andrea; Grifoni, Milena

    2016-03-01

    We demonstrate the nonequilibrium tip induced control of the spin state of copper phthalocyanine on an insulator coated substrate. We find that, under the condition of energetic proximity of many-body neutral excited states to the anionic ground state, the system can undergo a population inversion towards these excited states. The resulting state of the system is accompanied by a change in the total spin quantum number. Experimental signatures of the crossover are the appearance of additional nodal planes in the topographical scanning tunneling microscopy images as well as a strong suppression of the current near the center of the molecule. The robustness of the effect against moderate charge conserving relaxation processes has also been tested.

  5. Hydration-dependent dynamic crossover phenomenon in protein hydration water

    NASA Astrophysics Data System (ADS)

    Wang, Zhe; Fratini, Emiliano; Li, Mingda; Le, Peisi; Mamontov, Eugene; Baglioni, Piero; Chen, Sow-Hsin

    2014-10-01

    The characteristic relaxation time τ of protein hydration water exhibits a strong hydration level h dependence. The dynamic crossover is observed when h is higher than the monolayer hydration level hc=0.2-0.25 and becomes more visible as h increases. When h is lower than hc, τ only exhibits Arrhenius behavior in the measured temperature range. The activation energy of the Arrhenius behavior is insensitive to h, indicating a local-like motion. Moreover, the h dependence of the crossover temperature shows that the protein dynamic transition is not directly or solely induced by the dynamic crossover in the hydration water.

  6. 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…

  7. 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…

  8. A Randomized Crossover Comparison of Team-based Learning and Lecture Format on Learning Outcomes

    PubMed Central

    Remington, Tami L.; Wells, Trisha D.; Klein, Kristin C.; Guthrie, Sally K.; Tingen, Jeffrey M.; Marshall, Vincent D.; Dorsch, Michael P.

    2016-01-01

    Objective. To compare learning outcomes and student confidence between team-based learning (TBL) and lecture. Methods. A crossover study was conducted with 30 students divided into two sections. Each section was taught six therapeutic topics (three TBL and three lecture). There were two assessments of 24 questions each. A survey (Likert scale) assessing student confidence and attitudes was administered at the end. Results. A significantly higher overall examination score was observed for TBL as compared to lecture. Students were more confident in providing therapeutic recommendations following TBL. Higher survey scores favoring TBL were also seen related to critical-thinking skills and therapeutic knowledge. Conclusion. Learning outcomes and student confidence in performing higher-order tasks were significantly higher with TBL. The findings of this novel crossover type design showed that TBL is an effective pedagogy. PMID:27756928

  9. Stress as a Trigger for Relapses in IBD: A Case-Crossover Study

    PubMed Central

    Jaghult, Susanna; Saboonchi, Fredrik; Moller, Jette; Johansson, Unn-Britt; Wredling, Regina; Kapraali, Marjo

    2013-01-01

    Background It is important to identify factors that influence the risk of relapses in inflammatory bowel disease. Few studies have been conducted and with limited methodology. This prospective case-crossover study, aims to examine whether perceived stress has a short-term acute effect, namely whether it acts as a trigger, on the risk of relapse in inflammatory bowel disease. Methods Sixty patients with inflammatory bowel disease and in remission were included. The case-crossover design was employed, which is an epidemiological design developed to study triggers for acute events and diseases. To collect information regarding symptoms and potential trigger factors, such as perceived stress, a structured diary was constructed. The participants were instructed to fill in the diary daily during six months. Fifty patients completed the study. Results The analysis showed an effect for high level of perceived stress. Being exposed to “quite a lot” of stress, yield an increase in risk for relapse during the forthcoming day (OR = 4.8, 95% CI 1.09 - 21.10). No statistically increased risk for lower levels of perceived stress was found, although elevated effect estimates were found for “some” stress. Conclusion This study supports earlier findings regarding perceived stress as an important factor in triggering relapses in IBD. However, this is the first case-crossover study performed to explore the trigger risk of stress in this population. Further investigations with larger patient samples are needed to confirm the findings. PMID:27785220

  10. Microelectromechanical systems integrating molecular spin crossover actuators

    NASA Astrophysics Data System (ADS)

    Manrique-Juarez, Maria D.; Rat, Sylvain; Mathieu, Fabrice; Saya, Daisuke; Séguy, Isabelle; Leïchlé, Thierry; Nicu, Liviu; Salmon, Lionel; Molnár, Gábor; Bousseksou, Azzedine

    2016-08-01

    Silicon MEMS cantilevers coated with a 200 nm thin layer of the molecular spin crossover complex [Fe(H2B(pz)2)2(phen)] (H2B(pz)2 = dihydrobis(pyrazolyl)borate and phen = 1,10-phenantroline) were actuated using an external magnetic field and their resonance frequency was tracked by means of integrated piezoresistive detection. The light-induced spin-state switching of the molecules from the ground low spin to the metastable high spin state at 10 K led to a well-reproducible shift of the cantilever's resonance frequency (Δfr = -0.52 Hz). Control experiments at different temperatures using coated as well as uncoated devices along with simple calculations support the assignment of this effect to the spin transition. This latter translates into changes in mechanical behavior of the cantilever due to the strong spin-state/lattice coupling. A guideline for the optimization of device parameters is proposed so as to efficiently harness molecular scale movements for large-scale mechanical work, thus paving the road for nanoelectromechanical systems (NEMS) actuators based on molecular materials.

  11. Laser frequency stabilization using bichromatic crossover spectroscopy

    SciTech Connect

    Jeong, Taek; Seb Moon, Han

    2015-03-07

    We propose a Doppler-free spectroscopic method named bichromatic crossover spectroscopy (BCS), which we then use for the frequency stabilization of an off-resonant frequency that does not correspond to an atomic transition. The observed BCS in the 5S{sub 1/2} → 5P{sub 1/2} transition of {sup 87}Rb is related to the hyperfine structure of the conventional saturated absorption spectrum of this transition. Furthermore, the Doppler-free BCS is numerically calculated by considering all of the degenerate magnetic sublevels of the 5S{sub 1/2} → 5P{sub 1/2} transition in an atomic vapor cell, and is found to be in good agreement with the experimental results. Finally, we successfully achieve modulation-free off-resonant locking at the center frequency between the two 5S{sub 1/2}(F = 1 and 2) → 5P{sub 1/2}(F′ = 1) transitions using a polarization rotation of the BCS. The laser frequency stability was estimated to be the Allan variance of 2.1 × 10{sup −10} at 1 s.

  12. Standard Model thermodynamics across the electroweak crossover

    SciTech Connect

    Laine, M.; Meyer, M.

    2015-07-22

    Even though the Standard Model with a Higgs mass m{sub \\tiny H}=125 GeV possesses no bulk phase transition, its thermodynamics still experiences a “soft point” at temperatures around T=160 GeV, with a deviation from ideal gas thermodynamics. Such a deviation may have an effect on precision computations of weakly interacting dark matter relic abundances if their mass is in the few TeV range, or on leptogenesis scenarios operating in this temperature range. By making use of results from lattice simulations based on a dimensionally reduced effective field theory, we estimate the relevant thermodynamic functions across the crossover. The results are tabulated in a numerical form permitting for their insertion as a background equation of state into cosmological particle production/decoupling codes. We find that Higgs dynamics induces a non-trivial “structure” visible e.g. in the heat capacity, but that in general the largest radiative corrections originate from QCD effects, reducing the energy density by a couple of percent from the free value even at T>160 GeV.

  13. Standard Model thermodynamics across the electroweak crossover

    SciTech Connect

    Laine, M.; Meyer, M. E-mail: meyer@itp.unibe.ch

    2015-07-01

    Even though the Standard Model with a Higgs mass m{sub H} = 125GeV possesses no bulk phase transition, its thermodynamics still experiences a 'soft point' at temperatures around T = 160GeV, with a deviation from ideal gas thermodynamics. Such a deviation may have an effect on precision computations of weakly interacting dark matter relic abundances if their mass is in the few TeV range, or on leptogenesis scenarios operating in this temperature range. By making use of results from lattice simulations based on a dimensionally reduced effective field theory, we estimate the relevant thermodynamic functions across the crossover. The results are tabulated in a numerical form permitting for their insertion as a background equation of state into cosmological particle production/decoupling codes. We find that Higgs dynamics induces a non-trivial 'structure' visible e.g. in the heat capacity, but that in general the largest radiative corrections originate from QCD effects, reducing the energy density by a couple of percent from the free value even at T > 160GeV.

  14. High-order jamming crossovers and density anomalies.

    PubMed

    Pica Ciamarra, Massimo; Sollich, Peter

    2013-10-28

    We demonstrate that particles interacting via core-softened potentials exhibit a series of successive density anomalies upon isothermal compression, leading to oscillations in the diffusivity and thermal expansion coefficient, with the latter reaching negative values. These finite-temperature density anomalies are then shown to correspond to zero-temperature high-order jamming crossovers. These occur when particles are forced to come into contact with neighbours in successive coordination shells upon increasing the density. The crossovers induce anomalous behavior of the bulk modulus, which oscillates with density. We rationalize the dependence of these crossovers on the softness of the interaction potential, and relate the jamming crossovers and the anomalous diffusivity via the properties of the vibrational spectrum. PMID:26029762

  15. Electronic bidirectional valve circuit prevents crossover distortion and threshold effect

    NASA Technical Reports Server (NTRS)

    Kernick, A.

    1966-01-01

    Four-terminal network forms a bidirectional valve which will switch or alternate an ac signal without crossover distortion or threshold effect. In this network, an isolated control signal is sufficient for circuit turn-on.

  16. Species Transport Mechanisms Governing Crossover and Capacity Loss in Vanadium Redox Flow Batteries

    NASA Astrophysics Data System (ADS)

    Agar, Ertan

    Vanadium redox flow batteries (VRFBs) are an emerging energy storage technology that offers unique advantages for grid-scale energy storage due to their flexible design and decoupled power/energy feature. Despite their popularity, a series of technical challenges hinder their widespread implementation. Among these, capacity loss (i.e., loss of energy storage capability) due to the undesired species crossover across the membrane has been identified as the key issue limiting the longevity of these systems. This issue is primarily governed by the properties of the membrane and can be mitigated by using proper membrane architectures with desired features. Presently, identifying proper membrane architectures for VRFB systems is hampered by the lack of a fundamental understanding of the nature of species transport mechanisms and how they are related to the membrane properties and key operating conditions. This Ph.D. study seeks to address this critical challenge by exploring the fundamental mechanisms responsible for species transport within the membrane. The overall objective of this dissertation study is to establish a fundamental understanding of the multi-ionic transport in VRFB membranes by investigating the ionic transport mechanisms responsible for crossover, and utilize this understanding to reveal the role of membrane properties and operating conditions on the capacity loss. To achieve these goals, a combined experimental and computational study was designed. An experimentally validated, 2-D, transient VRFB model that can track the vanadium crossover and capture the related capacity loss was developed. In addition to the model, several electrochemical techniques were used to characterize different types of membrane and study the effects of various operating conditions on the species crossover. Using these computational and experimental tools, an in-depth understanding of the species transport mechanisms within the membrane and how they are related to membrane

  17. Spin-Crossover Molecular Solids Beyond Rigid Crystal Approximation

    NASA Astrophysics Data System (ADS)

    Gudyma, Iurii V.; Ivashko, Victor V.

    2016-04-01

    The qualitative analysis of the spin-crossover molecular solid with distortion effect is presented. A spin-crossover solid with effect of distortion is studied in the framework of the Ising-like model with two-order parameters under statistical approach, where the effect of elastic strain on inter-ion interaction is considered. These considerations lead to examination of the relation between the primary and secondary order parameters during temperature and pressure changes.

  18. Spin-Crossover Molecular Solids Beyond Rigid Crystal Approximation.

    PubMed

    Gudyma, Iurii V; Ivashko, Victor V

    2016-12-01

    The qualitative analysis of the spin-crossover molecular solid with distortion effect is presented. A spin-crossover solid with effect of distortion is studied in the framework of the Ising-like model with two-order parameters under statistical approach, where the effect of elastic strain on inter-ion interaction is considered. These considerations lead to examination of the relation between the primary and secondary order parameters during temperature and pressure changes. PMID:27075338

  19. SPECIFIC AND CROSS-OVER EFFECTS OF FOAM ROLLING ON ANKLE DORSIFLEXION RANGE OF MOTION

    PubMed Central

    Beardsley, Chris

    2016-01-01

    ABSTRACT Background Flexibility is an important physical quality. Self-myofascial release (SMFR) methods such as foam rolling (FR) increase flexibility acutely but how long such increases in range of motion (ROM) last is unclear. Static stretching (SS) also increases flexibility acutely and produces a cross-over effect to contralateral limbs. FR may also produce a cross-over effect to contralateral limbs but this has not yet been identified. Purpose To explore the potential cross-over effect of SMFR by investigating the effects of a FR treatment on the ipsilateral limb of 3 bouts of 30 seconds on changes in ipsilateral and contralateral ankle DF ROM and to assess the time-course of those effects up to 20 minutes post-treatment. Methods A within- and between-subject design was carried out in a convenience sample of 26 subjects, allocated into FR (n=13) and control (CON, n=13) groups. Ankle DF ROM was recorded at baseline with the in-line weight-bearing lunge test for both ipsilateral and contralateral legs and at 0, 5, 10, 15, 20 minutes following either a two-minute seated rest (CON) or 3 3 30 seconds of FR of the plantar flexors of the dominant leg (FR). Repeated measures ANOVA was used to examine differences in ankle DF ROM. Results No significant between-group effect was seen following the intervention. However, a significant within-group effect (p<0.05) in the FR group was seen between baseline and all post-treatment time-points (0, 5, 10, 15 and 20 minutes). Significant within-group effects (p<0.05) were also seen in the ipsilateral leg between baseline and at all post-treatment time-points, and in the contralateral leg up to 10 minutes post-treatment, indicating the presence of a cross-over effect. Conclusions FR improves ankle DF ROM for at least 20 minutes in the ipsilateral limb and up to 10 minutes in the contralateral limb, indicating that FR produces a cross-over effect into the contralateral limb. The mechanism producing these cross-over effects is

  20. The kinetochore prevents centromere-proximal crossover recombination during meiosis

    PubMed Central

    Vincenten, Nadine; Kuhl, Lisa-Marie; Lam, Isabel; Oke, Ashwini; Kerr, Alastair RW; Hochwagen, Andreas; Fung, Jennifer; Keeney, Scott; Vader, Gerben; Marston, Adèle L

    2015-01-01

    During meiosis, crossover recombination is essential to link homologous chromosomes and drive faithful chromosome segregation. Crossover recombination is non-random across the genome, and centromere-proximal crossovers are associated with an increased risk of aneuploidy, including Trisomy 21 in humans. Here, we identify the conserved Ctf19/CCAN kinetochore sub-complex as a major factor that minimizes potentially deleterious centromere-proximal crossovers in budding yeast. We uncover multi-layered suppression of pericentromeric recombination by the Ctf19 complex, operating across distinct chromosomal distances. The Ctf19 complex prevents meiotic DNA break formation, the initiating event of recombination, proximal to the centromere. The Ctf19 complex independently drives the enrichment of cohesin throughout the broader pericentromere to suppress crossovers, but not DNA breaks. This non-canonical role of the kinetochore in defining a chromosome domain that is refractory to crossovers adds a new layer of functionality by which the kinetochore prevents the incidence of chromosome segregation errors that generate aneuploid gametes. DOI: http://dx.doi.org/10.7554/eLife.10850.001 PMID:26653857

  1. The kinetochore prevents centromere-proximal crossover recombination during meiosis.

    PubMed

    Vincenten, Nadine; Kuhl, Lisa-Marie; Lam, Isabel; Oke, Ashwini; Kerr, Alastair Rw; Hochwagen, Andreas; Fung, Jennifer; Keeney, Scott; Vader, Gerben; Marston, Adèle L

    2015-12-14

    During meiosis, crossover recombination is essential to link homologous chromosomes and drive faithful chromosome segregation. Crossover recombination is non-random across the genome, and centromere-proximal crossovers are associated with an increased risk of aneuploidy, including Trisomy 21 in humans. Here, we identify the conserved Ctf19/CCAN kinetochore sub-complex as a major factor that minimizes potentially deleterious centromere-proximal crossovers in budding yeast. We uncover multi-layered suppression of pericentromeric recombination by the Ctf19 complex, operating across distinct chromosomal distances. The Ctf19 complex prevents meiotic DNA break formation, the initiating event of recombination, proximal to the centromere. The Ctf19 complex independently drives the enrichment of cohesin throughout the broader pericentromere to suppress crossovers, but not DNA breaks. This non-canonical role of the kinetochore in defining a chromosome domain that is refractory to crossovers adds a new layer of functionality by which the kinetochore prevents the incidence of chromosome segregation errors that generate aneuploid gametes.

  2. Separable Crossover-Promoting and Crossover-Constraining Aspects of Zip1 Activity during Budding Yeast Meiosis

    PubMed Central

    Voelkel-Meiman, Karen; Johnston, Cassandra; Thappeta, Yashna; Subramanian, Vijayalakshmi V.; Hochwagen, Andreas; MacQueen, Amy J.

    2015-01-01

    Accurate chromosome segregation during meiosis relies on the presence of crossover events distributed among all chromosomes. MutSγ and MutLγ homologs (Msh4/5 and Mlh1/3) facilitate the formation of a prominent group of meiotic crossovers that mature within the context of an elaborate chromosomal structure called the synaptonemal complex (SC). SC proteins are required for intermediate steps in the formation of MutSγ-MutLγ crossovers, but whether the assembled SC structure per se is required for MutSγ-MutLγ-dependent crossover recombination events is unknown. Here we describe an interspecies complementation experiment that reveals that the mature SC is dispensable for the formation of Mlh3-dependent crossovers in budding yeast. Zip1 forms a major structural component of the budding yeast SC, and is also required for MutSγ and MutLγ-dependent crossover formation. Kluyveromyces lactis ZIP1 expressed in place of Saccharomyces cerevisiae ZIP1 in S. cerevisiae cells fails to support SC assembly (synapsis) but promotes wild-type crossover levels in those nuclei that progress to form spores. While stable, full-length SC does not assemble in S. cerevisiae cells expressing K. lactis ZIP1, aggregates of K. lactis Zip1 displayed by S. cerevisiae meiotic nuclei are decorated with SC-associated proteins, and K. lactis Zip1 promotes the SUMOylation of the SC central element protein Ecm11, suggesting that K. lactis Zip1 functionally interfaces with components of the S. cerevisiae synapsis machinery. Moreover, K. lactis Zip1-mediated crossovers rely on S. cerevisiae synapsis initiation proteins Zip3, Zip4, Spo16, as well as the Mlh3 protein, as do the crossovers mediated by S. cerevisiae Zip1. Surprisingly, however, K. lactis Zip1-mediated crossovers are largely Msh4/Msh5 (MutSγ)-independent. This separation-of-function version of Zip1 thus reveals that neither assembled SC nor MutSγ is required for Mlh3-dependent crossover formation per se in budding yeast. Our data

  3. The dynamical crossover in attractive colloidal systems.

    PubMed

    Mallamace, Francesco; Corsaro, Carmelo; Stanley, H Eugene; Mallamace, Domenico; Chen, Sow-Hsin

    2013-12-01

    We study the dynamical arrest in an adhesive hard-sphere colloidal system. We examine a micellar suspension of the Pluronic-L64 surfactant in the temperature (T) and volume fraction (φ) phase diagram. According to mode-coupling theory (MCT), this system is characterized by a cusp-like singularity and two glassy phases: an attractive glass (AG) phase and a repulsive glass (RG) phase. The T - φ phase diagram of this system as confirmed by a previous series of scattering data also exhibits a Percolation Threshold (PT) line, a reentrant behavior (AG-liquid-RG), and a glass-to-glass transition. The AG phase can be generated out of the liquid phase by using T and φ as control parameters. We utilize viscosity and nuclear magnetic resonance (NMR) techniques. NMR data confirm all the characteristic properties of the colloidal system phase diagram and give evidence of the onset of a fractal-like percolating structure at a precise threshold. The MCT scaling laws used to study the shear viscosity as a function of φ and T show in both cases a fragile-to-strong liquid glass-forming dynamic crossover (FSC) located near the percolation threshold where the clustering process is fully developed. These results suggest a larger thermodynamic generality for this phenomenon, which is usually studied only as a function of the temperature. We also find that the critical values of the control parameters, coincident with the PT line, define the locus of the FSC. In the region between the FSC and the glass transition lines the system dynamics are dominated by clustering effects. We thus demonstrate that it is possible, using the conceptual framework provided by extended mode-coupling theory, to describe the way a system approaches dynamic arrest, taking into account both cage and hopping effects.

  4. The dynamical crossover in attractive colloidal systems

    SciTech Connect

    Mallamace, Francesco; Corsaro, Carmelo; Stanley, H. Eugene; Mallamace, Domenico; Chen, Sow-Hsin

    2013-12-07

    We study the dynamical arrest in an adhesive hard-sphere colloidal system. We examine a micellar suspension of the Pluronic-L64 surfactant in the temperature (T) and volume fraction (ϕ) phase diagram. According to mode-coupling theory (MCT), this system is characterized by a cusp-like singularity and two glassy phases: an attractive glass (AG) phase and a repulsive glass (RG) phase. The T − ϕ phase diagram of this system as confirmed by a previous series of scattering data also exhibits a Percolation Threshold (PT) line, a reentrant behavior (AG-liquid-RG), and a glass-to-glass transition. The AG phase can be generated out of the liquid phase by using T and ϕ as control parameters. We utilize viscosity and nuclear magnetic resonance (NMR) techniques. NMR data confirm all the characteristic properties of the colloidal system phase diagram and give evidence of the onset of a fractal-like percolating structure at a precise threshold. The MCT scaling laws used to study the shear viscosity as a function of ϕ and T show in both cases a fragile-to-strong liquid glass-forming dynamic crossover (FSC) located near the percolation threshold where the clustering process is fully developed. These results suggest a larger thermodynamic generality for this phenomenon, which is usually studied only as a function of the temperature. We also find that the critical values of the control parameters, coincident with the PT line, define the locus of the FSC. In the region between the FSC and the glass transition lines the system dynamics are dominated by clustering effects. We thus demonstrate that it is possible, using the conceptual framework provided by extended mode-coupling theory, to describe the way a system approaches dynamic arrest, taking into account both cage and hopping effects.

  5. Detection of crossover time scales in multifractal detrended fluctuation analysis

    NASA Astrophysics Data System (ADS)

    Ge, Erjia; Leung, Yee

    2013-04-01

    Fractal is employed in this paper as a scale-based method for the identification of the scaling behavior of time series. Many spatial and temporal processes exhibiting complex multi(mono)-scaling behaviors are fractals. One of the important concepts in fractals is crossover time scale(s) that separates distinct regimes having different fractal scaling behaviors. A common method is multifractal detrended fluctuation analysis (MF-DFA). The detection of crossover time scale(s) is, however, relatively subjective since it has been made without rigorous statistical procedures and has generally been determined by eye balling or subjective observation. Crossover time scales such determined may be spurious and problematic. It may not reflect the genuine underlying scaling behavior of a time series. The purpose of this paper is to propose a statistical procedure to model complex fractal scaling behaviors and reliably identify the crossover time scales under MF-DFA. The scaling-identification regression model, grounded on a solid statistical foundation, is first proposed to describe multi-scaling behaviors of fractals. Through the regression analysis and statistical inference, we can (1) identify the crossover time scales that cannot be detected by eye-balling observation, (2) determine the number and locations of the genuine crossover time scales, (3) give confidence intervals for the crossover time scales, and (4) establish the statistically significant regression model depicting the underlying scaling behavior of a time series. To substantive our argument, the regression model is applied to analyze the multi-scaling behaviors of avian-influenza outbreaks, water consumption, daily mean temperature, and rainfall of Hong Kong. Through the proposed model, we can have a deeper understanding of fractals in general and a statistical approach to identify multi-scaling behavior under MF-DFA in particular.

  6. A Link between Meiotic Prophase Progression and CrossoverControl

    SciTech Connect

    Carlton, Peter M.; Farruggio, Alfonso P.; Dernburg, Abby F.

    2005-07-06

    During meiosis, most organisms ensure that homologous chromosomes undergo at least one exchange of DNA, or crossover, to link chromosomes together and accomplish proper segregation. How each chromosome receives a minimum of one crossover is unknown. During early meiosis in Caenorhabditis elegans and many other species, chromosomes adopt a polarized organization within the nucleus, which normally disappears upon completion of homolog synapsis. Mutations that impair synapsis even between a single pair of chromosomes in C. elegans delay this nuclear reorganization. We quantified this delay by developing a classification scheme for discrete stages of meiosis. Immunofluorescence localization of RAD-51 protein revealed that delayed meiotic cells also contained persistent recombination intermediates. Through genetic analysis, we found that this cytological delay in meiotic progression requires double-strand breaks and the function of the crossover-promoting heteroduplex HIM-14 (Msh4) and MSH-5. Failure of X chromosome synapsis also resulted in impaired crossover control on autosomes, which may result from greater numbers and persistence of recombination intermediates in the delayed nuclei. We conclude that maturation of recombination events on chromosomes promotes meiotic progression, and is coupled to the regulation of crossover number and placement. Our results have broad implications for the interpretation of meiotic mutants, as we have shown that asynapsis of a single chromosome pair can exert global effects on meiotic progression and recombination frequency.

  7. Feshbach resonances and BCS-BEC crossover in optical lattices

    NASA Astrophysics Data System (ADS)

    Shen, Zhaochuan; Radzihovsky, Leo; Gurarie, Victor

    2012-02-01

    In this talk we study Feshbach resonances of fermionic atoms placed in a periodic potential. We investigate the criteria when such a system can be described by a Hubbard model with variable interaction strength in case of broad resonance, or by a tight binding model of atoms and molecules with can convert into each other on sites of the lattice in case of narrow resonances. Assuming the applicability of these models, we first study the BCS-BEC crossover for broad resonance. We find that while below half filling the system undergoes the conventional crossover from a BCS superconductor to a Bose condensate of molecules, above half filling the nature of the BEC phase changes to that of a condensate of molecules made of holes. Switching our attention to the case of narrow resonance, we find that the crossover takes the system from a BCS to hole-BEC regime, than back to BCS, and finally to a conventional BEC of atomic molecules. In the latter crossover, we find that the size of Cooper pairs/molecules changes non-monotonously, being larger in the BCS and smaller in the BEC regimes. Finally, at a unity filling we find a quantum phase transition from a band insulator to a BCS-BEC superfluid replacing the crossover.

  8. Juxtaposition of heterozygous and homozygous regions causes reciprocal crossover remodelling via interference during Arabidopsis meiosis.

    PubMed

    Ziolkowski, Piotr A; Berchowitz, Luke E; Lambing, Christophe; Yelina, Nataliya E; Zhao, Xiaohui; Kelly, Krystyna A; Choi, Kyuha; Ziolkowska, Liliana; June, Viviana; Sanchez-Moran, Eugenio; Franklin, Chris; Copenhaver, Gregory P; Henderson, Ian R

    2015-03-27

    During meiosis homologous chromosomes undergo crossover recombination. Sequence differences between homologs can locally inhibit crossovers. Despite this, nucleotide diversity and population-scaled recombination are positively correlated in eukaryote genomes. To investigate interactions between heterozygosity and recombination we crossed Arabidopsis lines carrying fluorescent crossover reporters to 32 diverse accessions and observed hybrids with significantly higher and lower crossovers than homozygotes. Using recombinant populations derived from these crosses we observed that heterozygous regions increase crossovers when juxtaposed with homozygous regions, which reciprocally decrease. Total crossovers measured by chiasmata were unchanged when heterozygosity was varied, consistent with homeostatic control. We tested the effects of heterozygosity in mutants where the balance of interfering and non-interfering crossover repair is altered. Crossover remodeling at homozygosity-heterozygosity junctions requires interference, and non-interfering repair is inefficient in heterozygous regions. As a consequence, heterozygous regions show stronger crossover interference. Our findings reveal how varying homolog polymorphism patterns can shape meiotic recombination.

  9. Licensing MLH1 sites for crossover during meiosis.

    PubMed

    Martín, Azahara C; Shaw, Peter; Phillips, Dylan; Reader, Steve; Moore, Graham

    2014-01-01

    During meiosis, homologous chromosomes synapse and recombine at sites marked by the binding of the mismatch repair protein MLH1. In hexaploid wheat, the Ph1 locus has a major effect on whether crossover occurs between homologues or between related homoeologues. Here we report that--in wheat-rye hybrids where homologues are absent--Ph1 affects neither the level of synapsis nor the number of MLH1. Thus in the case of wheat-wild relative hybrids, Ph1 must affect whether MLH1 sites are able to progress to crossover. The observed level of synapsis implies that Ph1 functions to promote homologue pairing rather than suppress homoeologue pairing in wheat. Therefore, Ph1 stabilises polyploidy in wheat by both promoting homologue pairing and preventing MLH1 sites from becoming crossovers on paired homoeologues during meiosis. PMID:25098240

  10. Licensing MLH1 sites for crossover during meiosis

    PubMed Central

    Martín, Azahara C.; Shaw, Peter; Phillips, Dylan; Reader, Steve; Moore, Graham

    2014-01-01

    During meiosis, homologous chromosomes synapse and recombine at sites marked by the binding of the mismatch repair protein MLH1. In hexaploid wheat, the Ph1 locus has a major effect on whether crossover occurs between homologues or between related homoeologues. Here we report that—in wheat–rye hybrids where homologues are absent—Ph1 affects neither the level of synapsis nor the number of MLH1. Thus in the case of wheat–wild relative hybrids, Ph1 must affect whether MLH1 sites are able to progress to crossover. The observed level of synapsis implies that Ph1 functions to promote homologue pairing rather than suppress homoeologue pairing in wheat. Therefore, Ph1 stabilises polyploidy in wheat by both promoting homologue pairing and preventing MLH1 sites from becoming crossovers on paired homoeologues during meiosis. PMID:25098240

  11. A new crossover sine model based on trigonometric model and its application to the crossover lattice equation of state

    NASA Astrophysics Data System (ADS)

    Lee, Yongjin; Shin, Moon Sam; Kim, Hwayong

    2008-12-01

    In this study, a new crossover sine model (CSM) n was developed from a trigonometric model [M. E. Fisher, S. Zinn, and P. J. Upton, Phys. Rev. B 59, 14533 (1999)]. The trigonometric model is a parametric formulation model that is used to represent the thermodynamic variables near a critical point. Although there are other crossover models based on this trigonometric model, such as the CSM and the analytical sine model, which is an analytic formulation of the CSM, the new sine model (NSM) employs a different approach from these two models in terms of the connections between the parametric variables of the trigonometric model and thermodynamic variables. In order to test the performance of the NSM, the crossover lattice equation of state [M. S. Shin, Y. Lee, and H. Kim, J. Chem. Thermodyn. 40, 174 (2008)] was applied using the NSM for correlations of various pure fluids and fluid mixtures. The results showed that over a wide range of states, the crossover lattice fluid (xLF)/NSM yields the saturated properties of pure fluids and the phase behavior of binary mixtures more accurately than the original lattice equation of state. Moreover, a comparison with the crossover lattice equation of state using the CSM (xLF/CSM) showed that the new model presents good correlation results that are comparable to the xLF/CSM.

  12. A new crossover sine model based on trigonometric model and its application to the crossover lattice equation of state.

    PubMed

    Lee, Yongjin; Shin, Moon Sam; Kim, Hwayong

    2008-12-21

    In this study, a new crossover sine model (CSM) n was developed from a trigonometric model [M. E. Fisher, S. Zinn, and P. J. Upton, Phys. Rev. B 59, 14533 (1999)]. The trigonometric model is a parametric formulation model that is used to represent the thermodynamic variables near a critical point. Although there are other crossover models based on this trigonometric model, such as the CSM and the analytical sine model, which is an analytic formulation of the CSM, the new sine model (NSM) employs a different approach from these two models in terms of the connections between the parametric variables of the trigonometric model and thermodynamic variables. In order to test the performance of the NSM, the crossover lattice equation of state [M. S. Shin, Y. Lee, and H. Kim, J. Chem. Thermodyn. 40, 174 (2008)] was applied using the NSM for correlations of various pure fluids and fluid mixtures. The results showed that over a wide range of states, the crossover lattice fluid (xLF)/NSM yields the saturated properties of pure fluids and the phase behavior of binary mixtures more accurately than the original lattice equation of state. Moreover, a comparison with the crossover lattice equation of state using the CSM (xLF/CSM) showed that the new model presents good correlation results that are comparable to the xLF/CSM.

  13. 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

  14. Sound modes at the BCS-BEC crossover

    SciTech Connect

    Heiselberg, H.

    2006-01-15

    First and second sound speeds are calculated for a uniform superfluid gas of Fermi atoms as a function of temperature, density, and interaction strength. The second sound speed is of particular interest as it is a clear signal of a superfluid component and it determines the critical temperature. The sound modes and their dependence on density, scattering length, and temperature are calculated in the BCS, molecular Bose-Einstein condensate (BEC), and unitarity limits and a smooth crossover is extrapolated. It is found that first and second sounds undergo avoided crossing on the BEC side due to mixing. Consequently, they are detectable at crossover both as density and thermal waves in traps.

  15. Synthesis and characterization of 1D iron(II) spin crossover coordination polymers with hysteresis.

    PubMed

    Bauer, Wolfgang; Lochenie, Charles; Weber, Birgit

    2014-02-01

    Purposeful ligand design was used for the synthesis of eight new 1D iron(II) spin crossover coordination polymers aiming for cooperative spin transitions with hysteresis. The results from magnetic measurements and X-ray structure analysis show that the combination of rigid linkers and a hydrogen bond network between the 1D chains is a promising tool to reach this goal. Five of the eight new samples show a cooperative spin transition with hysteresis with up to 43 K wide hysteresis loops.

  16. 49 CFR 236.203 - Hand operated crossover between main tracks; protection.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...) Electric locking of the switches of the crossover. Signals governing movements over either switch shall... crossover is occupied by a train, locomotive or car in such a manner as to foul the main track. It shall not... electric locking releases....

  17. 49 CFR 236.203 - Hand operated crossover between main tracks; protection.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...) Electric locking of the switches of the crossover. Signals governing movements over either switch shall... crossover is occupied by a train, locomotive or car in such a manner as to foul the main track. It shall not... electric locking releases....

  18. Estimating crossover frequencies and testing for numerical interference with highly polymorphic markers

    SciTech Connect

    Ott, J.

    1996-12-31

    Interference maybe viewed as having two aspects, numerical interference referring to the numbers of crossovers occurring, and positional interference referring to the positions of crossovers. Here, the focus is on numerical interference and on methods of testing for its presence. A dense map of highly polymorphic markers is assumed so that each crossover can be observed. General relationships are worked out between crossover distributions and underlying chiasma distributions. It is shown that crossover distributions may be invalid, and methods are developed to estimate valid crossover distributions from observed counts of crossovers. Based on valid estimates of crossover distributions, tests for interference and development of empirical map functions are outlined. The methods are applied to published data on human chromosomes 9 and 19. 16 refs., 1 fig., 3 tabs.

  19. Evidence for structural crossover in the supercritical state

    SciTech Connect

    Bolmatov, Dima E-mail: db663@cornell.edu; Brazhkin, V. V.; Ryzhov, V. N.; Fomin, Yu. D.; Trachenko, K.

    2013-12-21

    The state of matter above the critical point is terra incognita, and is loosely discussed as a physically homogeneous flowing state where no differences can be made between a liquid and a gas and where properties undergo no marked or distinct changes with pressure and temperature. In particular, the structure of supercritical state is currently viewed to be the same everywhere on the phase diagram, and to change only gradually and in a featureless way while moving along any temperature and pressure path above the critical point. Here, we demonstrate that this is not the case, but that there is a well-defined structural crossover instead. Evidenced by the qualitative changes of distribution functions of interatomic distances and angles, the crossover demarcates liquid-like and gas-like configurations and the presence of medium-range structural correlations. Importantly, the discovered structural crossover is closely related to both dynamic and thermodynamic crossovers operating in the supercritical state, providing new unexpected fundamental interlinks between the supercritical structure, dynamics, and thermodynamics.

  20. HADRON-QUARK CROSSOVER AND MASSIVE HYBRID STARS WITH STRANGENESS

    SciTech Connect

    Masuda, Kota; Hatsuda, Tetsuo; Takatsuka, Tatsuyuki

    2013-02-10

    Using the idea of smooth crossover from hadronic matter with hyperons to quark matter with strangeness, we show that the maximum mass (M {sub max}) of neutron stars with quark matter cores can be larger than those without quark matter cores. This is in contrast to the conventional softening of the equation of state due to exotic components at high density. The essential conditions for reaching our conclusion are that (1) the crossover takes place at relatively low densities, around three times the normal nuclear density and (2) the quark matter is strongly interacting in the crossover region. From these, the pressure of the system can be greater than that of purely hadronic matter at a given baryon density in the crossover density region and leads to M {sub max} greater than 2 solar mass. This conclusion is insensitive to the different choice of the hadronic equation of state with hyperons. We remark upon several implications of this result to the nuclear incompressibility, the hyperon mixing, and the neutrino cooling.

  1. 50 CFR 660.120 - Trawl fishery-crossover provisions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Trawl fishery-crossover provisions. 660.120 Section 660.120 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE (CONTINUED) FISHERIES OFF WEST COAST STATES West Coast Groundfish-Limited Entry Trawl Fisheries...

  2. 50 CFR 660.120 - Trawl fishery-crossover provisions.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Trawl fishery-crossover provisions. 660.120 Section 660.120 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE (CONTINUED) FISHERIES OFF WEST COAST STATES West Coast Groundfish-Limited Entry Trawl Fisheries...

  3. 50 CFR 660.120 - Trawl fishery-crossover provisions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Trawl fishery-crossover provisions. 660.120 Section 660.120 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE (CONTINUED) FISHERIES OFF WEST COAST STATES West Coast Groundfish-Limited Entry Trawl Fisheries...

  4. 50 CFR 660.120 - Trawl fishery-crossover provisions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Trawl fishery-crossover provisions. 660.120 Section 660.120 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE (CONTINUED) FISHERIES OFF WEST COAST STATES West Coast Groundfish-Limited Entry Trawl Fisheries...

  5. 50 CFR 660.120 - Trawl fishery-crossover provisions.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Trawl fishery-crossover provisions. 660.120 Section 660.120 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE (CONTINUED) FISHERIES OFF WEST COAST STATES West Coast Groundfish-Limited Entry Trawl Fisheries...

  6. Multifunctional materials exhibiting spin crossover and liquid-crystalline properties

    NASA Astrophysics Data System (ADS)

    Seredyuk, M.; Gaspar, Ana B.; Ksenofontov, V.; Reiman, S.; Galyametdinov, Y.; Haase, W.; Rentschler, E.; Gütlich, P.

    2005-11-01

    The physical characterization of a new class of Fe(II) multifunctional SCO materials exhibiting spin crossover and liquid crystalline properties in the room temperatures region is reported. Mössbauer spectroscopy, magnetic, differential scanning calorimetry (DSC), X-ray powder diffraction (XRD) and optical polarizing microscopy studies have been performed on such materials.

  7. Crossover Improvement for the Genetic Algorithm in Information Retrieval.

    ERIC Educational Resources Information Center

    Vrajitoru, Dana

    1998-01-01

    In information retrieval (IR), the aim of genetic algorithms (GA) is to help a system to find, in a huge documents collection, a good reply to a query expressed by the user. Analysis of phenomena seen during the implementation of a GA for IR has led to a new crossover operation, which is introduced and compared to other learning methods.…

  8. Ligand Induced Spin Crossover in Penta-Coordinated Ferric Dithiocarbamates

    NASA Astrophysics Data System (ADS)

    Ganguli, P.; Iyer, R. M.

    1981-09-01

    On addition of lewis bases to Fe(dtc)2X, ligand exchange takes place through a SN2 mechanism, with a parallel spin crossover in the ferric ion. The two species (S = 3/2 and S = 5/2) formed are in dynamic chemical equilibrium, and a slow decomposition is then initiated.

  9. Computational Fluid Dynamics Simulation of a Quadrupole Magnetic Sorter Flow Channel: Effect of Splitter Position on Nonspecific Crossover

    PubMed Central

    Sajja, V. S. K.; Kennedy, David J.; Todd, Paul W.; Hanley, Thomas R.

    2011-01-01

    In the Quadrupole Magnetic Sorter (QMS) magnetic particles enter a vertical flow annulus and are separated from non-magnetic particles by radial deflection into an outer annulus where the purified magnetic particles are collected via a flow splitter. The purity of magnetically isolated particles in QMS is affected by the migration of nonmagnetic particles across transport lamina in the annular flow channel. Computational Fluid Dynamics (CFD) simulations were used to predict the flow patterns, pressure drop and nonspecific crossover in QMS flow channel for the isolation of pancreatic islets of Langerhans. Simulation results were compared with the experimental results to validate the CFD model. Results of the simulations were used to show that one design gives up to 10% less nonspecific crossover than another and this model can be used to optimise the flow channel design to achieve maximum purity of magnetic particles. PMID:21984840

  10. NeuronCyto II: An automatic and quantitative solution for crossover neural cells in high throughput screening.

    PubMed

    Ong, Kok Haur; De, Jaydeep; Cheng, Li; Ahmed, Sohail; Yu, Weimiao

    2016-08-01

    Microscopy is a fundamental technology driving new biological discoveries. Today microscopy allows a large number of images to be acquired using, for example, High Throughput Screening (HTS) and 4D imaging. It is essential to be able to interrogate these images and extract quantitative information in an automated fashion. In the context of neurobiology, it is important to automatically quantify the morphology of neurons in terms of neurite number, length, branching and complexity, etc. One major issue in quantification of neuronal morphology is the "crossover" problem where neurites cross and it is difficult to assign which neurite belongs to which cell body. In the present study, we provide a solution to the "crossover" problem, the software package NeuronCyto II. NeuronCyto II is an interactive and user-friendly software package for automatic neurite quantification. It has a well-designed graphical user interface (GUI) with only a few free parameters allowing users to optimize the software by themselves and extract relevant quantitative information routinely. Users are able to interact with the images and the numerical features through the Result Inspector. The processing of neurites without crossover was presented in our previous work. Our solution for the "crossover" problem is developed based on our recently published work with directed graph theory. Both methods are implemented in NeuronCyto II. The results show that our solution is able to significantly improve the reliability and accuracy of the neurons displaying "crossover." NeuronCyto II is freely available at the website: https://sites.google.com/site/neuroncyto/, which includes user support and where software upgrades will also be placed in the future. © 2016 The Authors. Cytometry Part A Published by Wiley Periodicals, Inc. on behalf of ISAC. PMID:27233092

  11. Altered Crossover Distribution and Frequency in Spermatocytes of Infertile Men with Azoospermia.

    PubMed

    Ren, He; Ferguson, Kyle; Kirkpatrick, Gordon; Vinning, Tanya; Chow, Victor; Ma, Sai

    2016-01-01

    During meiosis, homologous chromosomes pair to facilitate the exchange of DNA at crossover sites along the chromosomes. The frequency and distribution of crossover formation are tightly regulated to ensure the proper progression of meiosis. Using immunofluorescence techniques, our group and others have studied the meiotic proteins in spermatocytes of infertile men, showing that this population displays a reduced frequency of crossovers compared to fertile men. An insufficient number of crossovers is thought to promote chromosome missegregation, in which case the faulty cell may face meiotic arrest or contribute to the production of aneuploid sperm. Increasing evidence in model organisms has suggested that the distribution of crossovers may also be important for proper chromosome segregation. In normal males, crossovers are shown to be rare near centromeres and telomeres, while frequent in subtelomeric regions. Our study aims to characterize the crossover distribution in infertile men with non-obstructive (NOA) and obstructive azoospermia (OA) along chromosomes 13, 18 and 21. Eight of the 16 NOA men and five of the 21 OA men in our study displayed reduced crossover frequency compared to control fertile men. Seven NOA men and nine OA men showed altered crossover distributions on at least one of the chromosome arms studied compared to controls. We found that although both NOA and OA men displayed altered crossover distributions, NOA men may be at a higher risk of suffering both altered crossover frequencies and distributions compared to OA men. Our data also suggests that infertile men display an increase in crossover formation in regions where they are normally inhibited, specifically near centromeres and telomeres. Finally, we demonstrated a decrease in crossovers near subtelomeres, as well as increased average crossover distance to telomeres in infertile men. As telomere-guided mechanisms are speculated to play a role in crossover formation in subtelomeres, future

  12. Altered Crossover Distribution and Frequency in Spermatocytes of Infertile Men with Azoospermia

    PubMed Central

    Ren, He; Ferguson, Kyle; Kirkpatrick, Gordon; Vinning, Tanya; Chow, Victor; Ma, Sai

    2016-01-01

    During meiosis, homologous chromosomes pair to facilitate the exchange of DNA at crossover sites along the chromosomes. The frequency and distribution of crossover formation are tightly regulated to ensure the proper progression of meiosis. Using immunofluorescence techniques, our group and others have studied the meiotic proteins in spermatocytes of infertile men, showing that this population displays a reduced frequency of crossovers compared to fertile men. An insufficient number of crossovers is thought to promote chromosome missegregation, in which case the faulty cell may face meiotic arrest or contribute to the production of aneuploid sperm. Increasing evidence in model organisms has suggested that the distribution of crossovers may also be important for proper chromosome segregation. In normal males, crossovers are shown to be rare near centromeres and telomeres, while frequent in subtelomeric regions. Our study aims to characterize the crossover distribution in infertile men with non-obstructive (NOA) and obstructive azoospermia (OA) along chromosomes 13, 18 and 21. Eight of the 16 NOA men and five of the 21 OA men in our study displayed reduced crossover frequency compared to control fertile men. Seven NOA men and nine OA men showed altered crossover distributions on at least one of the chromosome arms studied compared to controls. We found that although both NOA and OA men displayed altered crossover distributions, NOA men may be at a higher risk of suffering both altered crossover frequencies and distributions compared to OA men. Our data also suggests that infertile men display an increase in crossover formation in regions where they are normally inhibited, specifically near centromeres and telomeres. Finally, we demonstrated a decrease in crossovers near subtelomeres, as well as increased average crossover distance to telomeres in infertile men. As telomere-guided mechanisms are speculated to play a role in crossover formation in subtelomeres, future

  13. Case-Crossover Analysis of Air Pollution Health Effects: A Systematic Review of Methodology and Application

    PubMed Central

    Carracedo-Martínez, Eduardo; Taracido, Margarita; Tobias, Aurelio; Saez, Marc; Figueiras, Adolfo

    2010-01-01

    Background Case-crossover is one of the most used designs for analyzing the health-related effects of air pollution. Nevertheless, no one has reviewed its application and methodology in this context. Objective We conducted a systematic review of case-crossover (CCO) designs used to study the relationship between air pollution and morbidity and mortality, from the standpoint of methodology and application. Data sources and extraction A search was made of the MEDLINE and EMBASE databases. Reports were classified as methodologic or applied. From the latter, the following information was extracted: author, study location, year, type of population (general or patients), dependent variable(s), independent variable(s), type of CCO design, and whether effect modification was analyzed for variables at the individual level. Data synthesis The review covered 105 reports that fulfilled the inclusion criteria. Of these, 24 addressed methodological aspects, and the remainder involved the design’s application. In the methodological reports, the designs that yielded the best results in simulation were symmetric bidirectional CCO and time-stratified CCO. Furthermore, we observed an increase across time in the use of certain CCO designs, mainly symmetric bidirectional and time-stratified CCO. The dependent variables most frequently analyzed were those relating to hospital morbidity; the pollutants most often studied were those linked to particulate matter. Among the CCO-application reports, 13.6% studied effect modification for variables at the individual level. Conclusions The use of CCO designs has undergone considerable growth; the most widely used designs were those that yielded better results in simulation studies: symmetric bidirectional and time-stratified CCO. However, the advantages of CCO as a method of analysis of variables at the individual level are put to little use. PMID:20356818

  14. Sources and Structures of Mitotic Crossovers That Arise When BLM Helicase Is Absent in Drosophila

    PubMed Central

    LaFave, Matthew C.; Andersen, Sabrina L.; Stoffregen, Eric P.; Holsclaw, Julie K.; Kohl, Kathryn P.; Overton, Lewis J.; Sekelsky, Jeff

    2014-01-01

    The Bloom syndrome helicase, BLM, has numerous functions that prevent mitotic crossovers. We used unique features of Drosophila melanogaster to investigate origins and properties of mitotic crossovers that occur when BLM is absent. Induction of lesions that block replication forks increased crossover frequencies, consistent with functions for BLM in responding to fork blockage. In contrast, treatment with hydroxyurea, which stalls forks, did not elevate crossovers, even though mutants lacking BLM are sensitive to killing by this agent. To learn about sources of spontaneous recombination, we mapped mitotic crossovers in mutants lacking BLM. In the male germline, irradiation-induced crossovers were distributed randomly across the euchromatin, but spontaneous crossovers were nonrandom. We suggest that regions of the genome with a high frequency of mitotic crossovers may be analogous to common fragile sites in the human genome. Interestingly, in the male germline there is a paucity of crossovers in the interval that spans the pericentric heterochromatin, but in the female germline this interval is more prone to crossing over. Finally, our system allowed us to recover pairs of reciprocal crossover chromosomes. Sequencing of these revealed the existence of gene conversion tracts and did not provide any evidence for mutations associated with crossovers. These findings provide important new insights into sources and structures of mitotic crossovers and functions of BLM helicase. PMID:24172129

  15. 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…

  16. Crossover Cutting During Hamstring Fatigue Produces Transverse Plane Knee Control Deficits

    PubMed Central

    Nyland, John A.; Caborn, David N.M.; Shapiro, Robert; Johnson, Darren L.

    1999-01-01

    Objective: To assess the effects of eccentric work-induced hamstring fatigue on sagittal and transverse plane (axial) knee and ankle biodynamics and kinetics during a running crossover cut directional change (functional pivot shift). Design and Setting: A pretest-posttest, single-group intervention experimental design was employed. All data were collected in a biodynamics laboratory. Subjects: Twenty healthy athletic females were trained for 3 weeks in crossover cutting before testing. Measurements: Data were sampled during 3 unfatigued and 3 fatigued (20% eccentric isokinetic knee-flexor torque reduction) crossover cut trials. Three-dimensional kinematic and ground reaction-force data were sampled at 200 Hz and 1000 Hz, respectively, and joint moment estimates were calculated. Data were standardized to initial force-plate heelstrike for comparisons of mean differences between conditions using paired t tests with Bonferroni adjustments. Pearson product-moment correlations compared kinematic and eccentric hamstring-torque relationships. Results: During internal rotation phase 1, between heelstrike and impact absorption, mean internal rotation velocity increased by 21.2°/s ± 114°/s. During internal rotation phase II, mean peak transverse plane knee rotation during propulsion decreased by 3.1° ± 9°. During internal rotation phase II, mean peak ankle plantar flexor moment onsets occurred 12.7 ± 53 milliseconds earlier, and this activation demonstrated a moderately positive relationship with the onset of mean peak knee internal rotation during propulsion and a weak negative relationship with mean peak hamstring torque/lean body weight. Conclusions: The increased knee internal rotation velocity during phase I indicates transverse plane dynamic knee-control deficits during hamstring fatigue. Earlier peak ankle plantar-flexor moments and decreased internal rotation during phase II in the presence of hamstring fatigue may represent compensatory attempts at dynamic

  17. Critical Crossover Functions for Simple Fluids: Non-Analytical Scaling Determination of the Ising-Like Crossover Parameter

    NASA Astrophysics Data System (ADS)

    Garrabos, Yves; Lecoutre, Carole; Marre, Samuel; LeNeindre, Bernard

    2016-08-01

    A non-analytical scaling determination of the Ising-like crossover parameter is proposed considering the critical isochore of a simple fluid at finite distance from its critical temperature. The mean crossover functions, estimated from the bounded results of the massive renormalization scheme in field theory applied to the ( Φ 2) d2( n) model in three dimensions (d=3) and scalar order parameter (n=1), are used to formulate the corresponding scaling equations valid in two well-defined temperature ranges from the critical temperature. The validity range and the Ising-like nature of the corresponding crossover description are discussed in terms of a single Ising-like scale factor characterizing the critical isochore. The asymptotic value of this scale factor can be predicted within the Ising-like preasymptotic domain. Unfortunately, the absence of precise experimental data in such a close vicinity of the critical point leads the direct testing impossible. A contrario, from our scaling equations and the use of precise measurements performed at finite distance from the critical point, its local value can be estimated beyond the Ising-like preasymptotic domain. This non-analytical scaling determination only needs to make reference to the universal features estimated from the mean crossover functions and to introduce a single master dimensionless length common to all the simple fluids. This latter parameter guaranties the uniqueness of the physical length unit used for the theoretical crossover functions and the fluid singular properties when the generalized critical coordinates of the vapor-liquid critical point of each fluid are known. Xenon case along its critical isochore is considered as a typical example to demonstrate the singleness of the Ising-like crossover parameter. With the measurements at finite temperature range of the effective singular behaviors of the isothermal compressibility in the homogeneous domain, and the vapor-liquid coexisting densities in the

  18. The antiplaque efficacy of propolis-based herbal toothpaste: A crossover clinical study

    PubMed Central

    Bhat, Nagesh; Bapat, Salil; Asawa, Kailash; Tak, Mridula; Chaturvedi, Pulkit; Gupta, Vivek V.; George, Pradeep P.

    2015-01-01

    Background: In recent years, herbal products have been suggested as an economic, safe and probably effective alternative for prevention and control of various oral diseases. But still there are some products which need to be evaluated. Of lately, Propolis is one such product. To assess and compare the efficacy of herbal dentifrice containing Propolis with Miswak and Colgate total toothpastes in controlling plaque formation. Materials and Methods: A double blind, randomized, crossover study design was conducted among thirty healthy dental students. After oral prophylaxis all subjects were given a washout product for one week period. Subjects were then made to brush with (washout product) for 1 minute followed by 1 minute brushing with assigned test product. The baseline MGMPI plaque scores were recorded. Subjects were then refrained from oral hygiene for 24 hours, and were recalled to be re-disclosed and re-measured for plaque formation. This procedure was repeated according to crossover design after a washout period of (2 week). Statistical tests used were Krukalwallis and Wilcoxon sign rank test. Results: There was a significant difference in 24 hour score between the test products evaluated. When the change from baseline to 24 hours was analyzed, the test product Propolis resulted in a consistently and significantly (p < 0.05) lower MGMPI mean scores than the Colgate Total and Miswak toothpastes. Conclusion: Propolis was found to be safe and effective in reducing plaque accumulation when compared to Miswak and Colgate total toothpaste. PMID:26283831

  19. 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

  20. Theoretical Study of Spin Crossover in 30 Iron Complexes.

    PubMed

    Kepp, Kasper P

    2016-03-21

    Iron complexes are important spin crossover (SCO) systems with vital roles in oxidative metabolism and promising technological potential. The SCO tendency depends on the free energy balance of high- and low-spin states, which again depends on physical effects such as dispersion, relativistic effects, and vibrational entropy. This work studied 30 different iron SCO systems with experimentally known thermochemical data, using 12 different density functionals. Remarkably general entropy-enthalpy compensation across SCO systems was identified (R = 0.82, p = 0.002) that should be considered in rational SCO design. Iron(II) complexes displayed higher ΔH and ΔS values than iron(III) complexes and also less steep compensation effects. First-coordination sphere ΔS values computed from numerical frequencies reproduce most of the experimental entropy and should thus be included when modeling spin-state changes in inorganic chemistry (R = 0.52, p = 3.4 × 10(-3); standard error in TΔS ≈ 4.4 kJ/mol at 298 K vs 16 kJ/mol of total TΔS on average). Zero-point energies favored high-spin states by 9 kJ/mol on average. Interestingly, dispersion effects are surprisingly large for the SCO process (average: 9 kJ/mol, but up to 33 kJ/mol) and favor the more compact low-spin state. Relativistic effects favor low-spin by ∼9 kJ/mol on average, but up to 24 kJ/mol. B3LYP*, TPSSh, B2PLYP, and PW6B95 performed best for the typical calculation scheme that includes ZPE. However, if relativistic and dispersion effects are included, only B3LYP* remained accurate. On average, high-spin was favored by LYP by 11-15 kJ/mol relative to other correlation functionals, and by 4.2 kJ/mol per 1% HF exchange in hybrids. 13% HF exchange was optimal without dispersion, and 15% was optimal with all effects included for these systems. PMID:26913489

  1. Comparison of the Carbon System Parameters at the Global CO2 Survey Crossover Locations in the North and South Pacific Ocean, 1990-1996

    SciTech Connect

    Feely, Richard A; Lamb, Marilyn F.; Greeley, Dana J.; Wanninkhof, Rik

    1999-10-01

    As a collaborative program to measure global ocean carbon inventories and provide estimates of the anthropogenic carbon dioxide (C02) uptake by the oceans. the National Oceanic and Atmospheric Administration and the U.S. Department of Energy have sponsored the collection of ocean carbon measurements as part of the World Ocean Circulation Experiment and Ocean-Atmosphere Carbon Exchange Study cruises. The cruises discussed here occurred in the North and South Pacific from 1990 through 1996. The carbon parameters from these 30 crossover locations have been compared to ensure that a consistent global data set emerges from the survey cruises. !'he results indicate that for dissolved inorganic carbon. fugacity of C02• and pH. the a~:,rreements at most crossover locations are well within the design specifications for the global CO) survey: whereas. in the case of total alkaliniry. the agreement between crossover locations is not as close.

  2. 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…

  3. 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:…

  4. Effects of Risperidone on Aberrant Behavior of Persons with Developmental Disabilities: I. A Double-Blind Crossover Study Using Multiple Measures.

    ERIC Educational Resources Information Center

    Zarcone, Jennifer R.; Hellings, Jessica A.; Crandall, Kurt; Reese, R. Matthew; Marquis, Janet; Fleming, Kandace; Shores, Richard; Williams, Dean; Schroeder, Stephen R.

    2001-01-01

    The efficacy of the atypical antipsychotic risperidone was evaluated in the treatment of aberrant behavior (e.g., aggression, self-injury) in 20 individuals with developmental disabilities. The study, a double-blind crossover design, identified 50 percent of participants as responders. Naturalistic observations of five participants showed that…

  5. In-Country TEFL/Crossover Tropical Agricultural Training Manual. Trainee Edition. Training for Development. Peace Corps Information Collection & Exchange Training Manual No. T-37A.

    ERIC Educational Resources Information Center

    Franck, Carl R.; And Others

    Correlated to the trainer's manual for the same course, this trainee's manual has been designed for Peace Corps trainees coming to Thailand without stateside agricultural training. Although it was developed for the training of Test of English as a Foreign Language (TEFL)/Crossovers, the majority of sessions are appropriate for other Peace Corps…

  6. Development of anode zone using dual-anode system to reduce organic matter crossover in membraneless microbial fuel cells.

    PubMed

    Kim, Jisu; Kim, Bongkyu; An, Junyeong; Lee, Yoo Seok; Chang, In Seop

    2016-08-01

    To prevent the occurrence of the organic crossover in membraneless microbial fuel cells (ML-MFCs), dual-anode MFC (DA-MFC) was designed from multi-anode concept to ensure anode zone. The anode zone addressed increase the utilization of organic matter in ML-MFCs, as the result, the organic crossover was prevented and performance of MFCs were enhanced. The maximum power of the DA-MFC was 0.46mW, which is about 1.56 times higher than the ML-MFC (0.29mW). Furthermore, the DA-MFC had advantage in correlation of organic substance concentration and dissolved oxygen concentration, and even electric over-potential. In addition, in terms of cathode fouling, the DA-MFC showed clearer surface. Hence, the anode zone should be considered in the advanced ML-MFC for practically use in wastewater treatment process, and also for scale-up of MFCs.

  7. Isospin Dependent Pairing Interactions and BCS-BEC crossover

    SciTech Connect

    Sagawa, H.; Margueron, J.; Hagino, K.

    2008-11-11

    We propose new types of density dependent contact pairing interaction which reproduce the pairing gaps in symmetric and neutron matters obtained by a microscopic treatment based on the realistic nucleon-nucleon interaction. The BCS-BEC crossover of neutrons pairs in symmetric and asymmetric nuclear matters is studied by using these contact interactions. It is shown that the bare and screened pairing interactions lead to different features of the BCS-BEC crossover in symmetric nuclear matter. We perform Hartree-Fock-Bogoliubov (HFB) calculations for semi-magic Calcium, Nickel, Tin and Lead isotopes and N = 20, 28, 50 and 82 isotones using these density-dependent pairing interactions. Our calculations well account for the experimental data for the neutron number dependence of binding energy, two neutrons separation energy, and odd-even mass staggering of these isotopes. Especially the interaction IS+IV Bare without the medium polarization effect gives satisfactory results for all the isotopes.

  8. Net baryon fluctuations from a crossover equation of state

    NASA Astrophysics Data System (ADS)

    Kapusta, J.; Albright, M.; Young, C.

    2016-08-01

    We have constructed an equation of state which smoothly interpolates between an excluded-volume hadron resonance gas at low energy density to a plasma of quarks and gluons at high energy density. This crossover equation of state agrees very well with lattice calculations at both zero and nonzero baryon chemical potential. We use it to compute the variance, skewness, and kurtosis of fluctuations of baryon number, and compare to measurements of proton number fluctuations in central Au-Au collisions as measured by the STAR Collaboration in a beam energy scan at the Relativistic Heavy-Ion Collider. The crossover equation of state can reproduce the data if the fluctuations are frozen out at temperatures well below than the average chemical freeze-out.

  9. Spin crossover in ferropericlase and its influence on mantle velocities

    NASA Astrophysics Data System (ADS)

    Wentzcovitch, R. M.; Wu, Z.; Justo, J. F.; Hsu, H.; da Silva, C. R.; Wang, J.; Bass, J. D.

    2010-12-01

    The high to low spin crossover of iron in ferropericlase impacts on mantle properties and on how we simulate and interpret mantle observations. We have calculated by first principles and measured the elastic properties of ferropericlase with various compositions at high pressures and temperatures. We observe no anomalies in the shear properties. Here we investigate the effect of the spin crossover of ferropericlase on the elastic moduli of a uniform aggregate with pyrolite composition. We address one dimensional velocity profiles along a typical geotherm and lateral velocity anomalies caused by lateral temperature variations. This work was supported by NSF under ATM-0428774 (VLab) and EAR-1019853. The computations were performed at the Minnesota Supercomputing Institute (MSI).

  10. Excitonic correlation in the Mott crossover regime in Ge

    NASA Astrophysics Data System (ADS)

    Sekiguchi, Fumiya; Shimano, Ryo

    2015-04-01

    Exciton Mott transition (EMT) in Ge was investigated by using optical-pump and terahertz-probe spectroscopy. From the quantitative analysis of optical conductivity and dielectric function, we evaluated the densities of unbound electron-hole pairs and excitons after the photoexcitation, from which we determined the ionization ratio of excitons α. The Mott crossover density region in Ge was elucidated from the density dependence of α in the temperature range above the critical temperature of electron-hole droplets. The 1 s -2 p excitonic transition energy hardly shifted with increasing density toward the EMT. Combined with the similar results recently observed in bulk Si, we suggest that the robustness of excitonic correlation against the Coulomb screening is a universal feature in bulk semiconductors in the Mott crossover regime.

  11. Particle-hole fluctuations in BCS-BEC crossover

    SciTech Connect

    Floerchinger, S.; Scherer, M.; Wetterich, C.; Diehl, S.

    2008-11-01

    The effect of particle-hole fluctuations for the BCS-BEC crossover is investigated by use of functional renormalization. We compute the Gorkov effect and the critical temperature for the whole range in the scattering length a. On the BCS side for small negative a we recover the Gorkov approximation, while on the BEC side of small positive a the particle-hole fluctuations play no important role, and we find a system of interacting bosons. In the unitarity limit of infinite scattering length our quantitative estimate yields T{sub c}/T{sub F}=0.264. We also investigate the crossover from broad to narrow Feshbach resonances - for the latter we obtain T{sub c}/T{sub F}=0.204 for a{sup -1}=0. A key ingredient for our treatment is the computation of the momentum dependent four-fermion vertex and its bosonization in terms of an effective bound-state exchange.

  12. Crossover behavior in hydrogen sensing mechanism for palladium ultrathin films.

    SciTech Connect

    Darling, S. B.; Ramanathan, M.; Skudlarek, G.; Wang, H. H.; Illinois Math and Science Academy

    2010-01-01

    Palladium has been extensively studied as a material for hydrogen sensors because of the simplicity of its reversible resistance change when exposed to hydrogen gas. Various palladium films and nanostructures have been used, and different responses have been observed with these diverse morphologies. In some cases, such as with nanowires, the resistance will decrease, whereas in others, such as with thick films, the resistance will increase. Each of these mechanisms has been explored for several palladium structures, but the crossover between them has not been systematically investigated. Here we report on a study aimed at deciphering the nanostructure-property relationships of ultrathin palladium films used as hydrogen gas sensors. The crossover in these films is observed at a thickness of {approx} 5 nm. Ramifications for future sensor developments are discussed.

  13. Hyperon puzzle, hadron-quark crossover and massive neutron stars

    NASA Astrophysics Data System (ADS)

    Masuda, Kota; Hatsuda, Tetsuo; Takatsuka, Tatsuyuki

    2016-03-01

    Bulk properties of cold and hot neutron stars are studied on the basis of the hadron-quark crossover picture where a smooth transition from the hadronic phase to the quark phase takes place at finite baryon density. By using a phenomenological equation of state (EOS) "CRover", which interpolates the two phases at around 3 times the nuclear matter density (ρ0, it is found that the cold NSs with the gravitational mass larger than 2M_{odot} can be sustained. This is in sharp contrast to the case of the first-order hadron-quark transition. The radii of the cold NSs with the CRover EOS are in the narrow range (12.5 ± 0.5) km which is insensitive to the NS masses. Due to the stiffening of the EOS induced by the hadron-quark crossover, the central density of the NSs is at most 4 ρ0 and the hyperon-mixing barely occurs inside the NS core. This constitutes a solution of the long-standing hyperon puzzle. The effect of color superconductivity (CSC) on the NS structures is also examined with the hadron-quark crossover. For the typical strength of the diquark attraction, a slight softening of the EOS due to two-flavor CSC (2SC) takes place and the maximum mass is reduced by about 0.2M_{odot}. The CRover EOS is generalized to the supernova matter at finite temperature to describe the hot NSs at birth. The hadron-quark crossover is found to decrease the central temperature of the hot NSs under isentropic condition. The gravitational energy release and the spin-up rate during the contraction from the hot NS to the cold NS are also estimated.

  14. Intrinsic DNA curvature of double-crossover tiles

    NASA Astrophysics Data System (ADS)

    Kim, Seungjae; Kim, Junghoon; Qian, Pengfei; Shin, Jihoon; Amin, Rashid; Ahn, Sang Jung; LaBean, Thomas H.; Kim, Moon Ki; Park, Sung Ha

    2011-06-01

    A theoretical model which takes into account the structural distortion of double-crossover DNA tiles has been studied to investigate its effect on lattice formation sizes. It has been found that a single vector appropriately describes the curvature of the tiles, of which a higher magnitude hinders lattice growth. In conjunction with these calculations, normal mode analysis reveals that tiles with relative higher frequencies have an analogous effect. All the theoretical results are shown to be in good agreement with experimental data.

  15. Flow equations for the BCS-BEC crossover

    SciTech Connect

    Diehl, S.; Gies, H.; Pawlowski, J. M.; Wetterich, C.

    2007-08-15

    The functional renormalization group is used for the BCS-BEC crossover in gases of ultracold fermionic atoms. In a simple truncation, we see how universality and an effective theory with composite bosonic diatom states emerge. We obtain a unified picture of the whole phase diagram. The flow reflects different effective physics at different scales. In the BEC limit as well as near the critical temperature, it describes an interacting bosonic theory.

  16. Dynamical and orientational structural crossovers in low-temperature glycerol.

    PubMed

    Seyedi, Salman; Martin, Daniel R; Matyushov, Dmitry V

    2016-07-01

    Mean-square displacements of hydrogen atoms in glass-forming materials and proteins, as reported by incoherent elastic neutron scattering, show kinks in their temperature dependence. This crossover, known as the dynamical transition, connects two approximately linear regimes. It is often assigned to the dynamical freezing of subsets of molecular modes at the point of equality between their corresponding relaxation times and the instrumental observation window. The origin of the dynamical transition in glass-forming glycerol is studied here by extensive molecular dynamics simulations. We find the dynamical transition to occur for both the center-of-mass translations and the molecular rotations at the same temperature, insensitive to changes of the observation window. Both the translational and rotational dynamics of glycerol show a dynamic crossover from the structural to a secondary relaxation at the temperature of the dynamical transition. A significant and discontinuous increase in the orientational Kirkwood factor and in the dielectric constant is observed in the same range of temperatures. No indication is found of a true thermodynamic transition to an ordered low-temperature phase. We therefore suggest that all observed crossovers are dynamic in character. The increase in the dielectric constant is related to the dynamic freezing of dipolar domains on the time scale of simulations.

  17. Universal crossovers between entanglement entropy and thermal entropy

    NASA Astrophysics Data System (ADS)

    Swingle, Brian; Senthil, T.

    2013-01-01

    We postulate the existence of universal crossover functions connecting the universal parts of the entanglement entropy to the low-temperature thermal entropy in gapless quantum many-body systems. These scaling functions encode the intuition that the same low-energy degrees of freedom which control low-temperature thermal physics are also responsible for the long-range entanglement in the quantum ground state. We demonstrate the correctness of the proposed scaling form and determine the scaling function for certain classes of gapless systems whose low-energy physics is described by a conformal field theory. We also use our crossover formalism to argue that local systems which are “natural” can violate the boundary law at most logarithmically. In particular, we show that several non-Fermi-liquid phases of matter have entanglement entropy that is at most of order Ld-1log(L) for a region of linear size L thereby confirming various earlier suggestions in the literature. We also briefly apply our crossover formalism to the study of fluctuations in conserved quantities and discuss some subtleties that occur in systems that spontaneously break a continuous symmetry.

  18. Dynamical and orientational structural crossovers in low-temperature glycerol.

    PubMed

    Seyedi, Salman; Martin, Daniel R; Matyushov, Dmitry V

    2016-07-01

    Mean-square displacements of hydrogen atoms in glass-forming materials and proteins, as reported by incoherent elastic neutron scattering, show kinks in their temperature dependence. This crossover, known as the dynamical transition, connects two approximately linear regimes. It is often assigned to the dynamical freezing of subsets of molecular modes at the point of equality between their corresponding relaxation times and the instrumental observation window. The origin of the dynamical transition in glass-forming glycerol is studied here by extensive molecular dynamics simulations. We find the dynamical transition to occur for both the center-of-mass translations and the molecular rotations at the same temperature, insensitive to changes of the observation window. Both the translational and rotational dynamics of glycerol show a dynamic crossover from the structural to a secondary relaxation at the temperature of the dynamical transition. A significant and discontinuous increase in the orientational Kirkwood factor and in the dielectric constant is observed in the same range of temperatures. No indication is found of a true thermodynamic transition to an ordered low-temperature phase. We therefore suggest that all observed crossovers are dynamic in character. The increase in the dielectric constant is related to the dynamic freezing of dipolar domains on the time scale of simulations. PMID:27575188

  19. Automatic identification of vessel crossovers in retinal images

    NASA Astrophysics Data System (ADS)

    Sánchez, L.; Barreira, N.; Penedo, M. G.; Cancela, B.

    2015-02-01

    Crossovers and bifurcations are interest points of the retinal vascular tree useful to diagnose diseases. Specifically, detecting these interest points and identifying which of them are crossings will give us the opportunity to search for arteriovenous nicking, this is, an alteration of the vessel tree where an artery is crossed by a vein and the former compresses the later. These formations are a clear indicative of hypertension, among other medical problems. There are several studies that have attempted to define an accurate and reliable method to detect and classify these relevant points. In this article, we propose a new method to identify crossovers. Our approach is based on segmenting the vascular tree and analyzing the surrounding area of each interest point. The minimal path between vessel points in this area is computed in order to identify the connected vessel segments and, as a result, to distinguish between bifurcations and crossovers. Our method was tested using retinographies from public databases DRIVE and VICAVR, obtaining an accuracy of 90%.

  20. Dynamical and orientational structural crossovers in low-temperature glycerol

    NASA Astrophysics Data System (ADS)

    Seyedi, Salman; Martin, Daniel R.; Matyushov, Dmitry V.

    2016-07-01

    Mean-square displacements of hydrogen atoms in glass-forming materials and proteins, as reported by incoherent elastic neutron scattering, show kinks in their temperature dependence. This crossover, known as the dynamical transition, connects two approximately linear regimes. It is often assigned to the dynamical freezing of subsets of molecular modes at the point of equality between their corresponding relaxation times and the instrumental observation window. The origin of the dynamical transition in glass-forming glycerol is studied here by extensive molecular dynamics simulations. We find the dynamical transition to occur for both the center-of-mass translations and the molecular rotations at the same temperature, insensitive to changes of the observation window. Both the translational and rotational dynamics of glycerol show a dynamic crossover from the structural to a secondary relaxation at the temperature of the dynamical transition. A significant and discontinuous increase in the orientational Kirkwood factor and in the dielectric constant is observed in the same range of temperatures. No indication is found of a true thermodynamic transition to an ordered low-temperature phase. We therefore suggest that all observed crossovers are dynamic in character. The increase in the dielectric constant is related to the dynamic freezing of dipolar domains on the time scale of simulations.

  1. Unravelling the chemical design of spin-crossover nanoparticles based on iron(ii)–triazole coordination polymers: towards a control of the spin transition† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c5tc01093d Click here for additional data file.

    PubMed Central

    Giménez-Marqués, Mónica; García-Sanz de Larrea, M. Luisa

    2015-01-01

    A systematic study of the key synthetic parameters that control the growth of spin-crossover (SCO) nanoparticles (NPs) using the reverse micelle technique has been undertaken in the system [Fe(Htrz)2(trz)](BF4)·H2O, (Htrz = 1,2,4-triazole). This has permitted us to modulate the physical properties of the NPs in a controlled and reproducible manner. In particular, a control over the size of the NPs (in the range 4 to 16 nm) has been achieved by varying the water to surfactant molar ratio. The consequences of this size variation on the cooperativity of the spin transition are discussed. Finally, this approach has been extended to the chemical alloy [Fe(Htrz)2.95(NH2trz)0.05](ClO4)2 in order to prepare NPs exhibiting a cooperative and hysteretic spin transition centred closer to room temperature. PMID:27358736

  2. Fine-Scale Crossover Rate Variation on the Caenorhabditis elegans X Chromosome

    PubMed Central

    Bernstein, Max R.; Rockman, Matthew V.

    2016-01-01

    Meiotic recombination creates genotypic diversity within species. Recombination rates vary substantially across taxa, and the distribution of crossovers can differ significantly among populations and between sexes. Crossover locations within species have been found to vary by chromosome and by position within chromosomes, where most crossover events occur in small regions known as recombination hotspots. However, several species appear to lack hotspots despite significant crossover heterogeneity. The nematode Caenorhabditis elegans was previously found to have the least fine-scale variation in crossover distribution among organisms studied to date. It is unclear whether this pattern extends to the X chromosome given its unique compaction through the pachytene stage of meiotic prophase in hermaphrodites. We generated 798 recombinant nested near-isogenic lines (NILs) with crossovers in a 1.41 Mb region on the left arm of the X chromosome to determine if its recombination landscape is similar to that of the autosomes. We find that the fine-scale variation in crossover rate is lower than that of other model species, and is inconsistent with hotspots. The relationship of genomic features to crossover rate is dependent on scale, with GC content, histone modifications, and nucleosome occupancy being negatively associated with crossovers. We also find that the abundances of 4- to 6-bp DNA motifs significantly explain crossover density. These results are consistent with recombination occurring at unevenly distributed sites of open chromatin. PMID:27172189

  3. A simple, analytic model of polymer electrolyte membrane fuel cell anode recirculation at operating power including nitrogen crossover

    NASA Astrophysics Data System (ADS)

    Promislow, Keith; St-Pierre, Jean; Wetton, Brian

    A simple, analytic model is presented that describes the steady state profile of anode nitrogen concentration in a polymer electrolyte membrane fuel cell operated with anode recirculation. The model is appropriate for fuel cells with straight gas channels and includes the effect of nitrogen crossover from cathode to anode through the membrane. The key analytic simplification in the model is that this crossover rate, when scaled to the gas flows in the channels, is small. This is a good approximation when the device is used at operating power levels. The model shows that the characteristic times for the anode nitrogen profiles to reach steady state are of the order of minutes and that the dilution effect of anode nitrogen is severe for pure recirculation. The model shows additionally that a small anode outlet bleed can significantly reduce the nitrogen dilution effect. Within the framework of the model, the energy efficiency of pure recirculation can be compared to hydrogen venting or partial anode bleeding. An optimal bleed rate is identified. The model and optimization analysis can be adapted to other fuel cell designs and operating conditions. Along with operating conditions, only two key parameters are needed: a nitrogen crossover coefficient and the marginal efficiency loss to compressors for increased anode stoichiometric gas flow.

  4. Dimer Involvement and Origin of Crossover in Nickel-Catalyzed Aldehyde–Alkyne Reductive Couplings

    PubMed Central

    2015-01-01

    The mechanism of nickel(0)-catalyzed reductive coupling of aldehydes and alkynes has been studied. Extensive double-labeling crossover studies have been conducted. While previous studies illustrated that phosphine- and N-heterocyclic carbene-derived catalysts exhibited differing behavior, the origin of these effects has now been evaluated in detail. Many variables, including ligand class, sterics of the ligand and alkyne, temperature, and ring size being formed in intramolecular versions, all influence the extent of crossover observed. A computational evaluation of these effects suggests that dimerization of a key metallacyclic intermediate provides the origin of crossover. Protocols that proceed with crossover are typically less efficient than those without crossover given the thermodynamic stability and low reactivity of the dimeric metallacycles involved in crossover pathways. PMID:25401337

  5. Control of cross-over by single-strand DNA resection.

    PubMed

    Prado, Félix; Aguilera, Andrés

    2003-08-01

    Control of DNA cross-overs is necessary for meiotic recombination and genome integrity. The frequency of cross-overs is dependent on homology length and the conversion tract, but the mechanisms underlying the regulation of cross-overs remain unknown. We propose that 5'-end resection, a key intermediate in double-strand break repair, could determine the formation of cross-overs. Extensive DNA resection might favor gene conversion without cross-over by channeling recombination events through synthesis-dependent strand-annealing. In reactions with short regions of homology, resection beyond the homologous sequence would impede Holliday junction formation and, consequently, cross-over. Extensive DNA resection could be an effective mechanism to prevent reciprocal exchanges between dispersed DNA sequences, and thus contribute to the genome stability.

  6. REC, Drosophila MCM8, drives formation of meiotic crossovers.

    PubMed

    Blanton, Hunter L; Radford, Sarah J; McMahan, Susan; Kearney, Hutton M; Ibrahim, Joseph G; Sekelsky, Jeff

    2005-09-01

    Crossovers ensure the accurate segregation of homologous chromosomes from one another during meiosis. Here, we describe the identity and function of the Drosophila melanogaster gene recombination defective (rec), which is required for most meiotic crossing over. We show that rec encodes a member of the mini-chromosome maintenance (MCM) protein family. Six MCM proteins (MCM2-7) are essential for DNA replication and are found in all eukaryotes. REC is the Drosophila ortholog of the recently identified seventh member of this family, MCM8. Our phylogenetic analysis reveals the existence of yet another family member, MCM9, and shows that MCM8 and MCM9 arose early in eukaryotic evolution, though one or both have been lost in multiple eukaryotic lineages. Drosophila has lost MCM9 but retained MCM8, represented by REC. We used genetic and molecular methods to study the function of REC in meiotic recombination. Epistasis experiments suggest that REC acts after the Rad51 ortholog SPN-A but before the endonuclease MEI-9. Although crossovers are reduced by 95% in rec mutants, the frequency of noncrossover gene conversion is significantly increased. Interestingly, gene conversion tracts in rec mutants are about half the length of tracts in wild-type flies. To account for these phenotypes, we propose that REC facilitates repair synthesis during meiotic recombination. In the absence of REC, synthesis does not proceed far enough to allow formation of an intermediate that can give rise to crossovers, and recombination proceeds via synthesis-dependent strand annealing to generate only noncrossover products.

  7. Single water entropy: hydrophobic crossover and application to drug binding.

    PubMed

    Sasikala, Wilbee D; Mukherjee, Arnab

    2014-09-11

    Entropy of water plays an important role in both chemical and biological processes e.g. hydrophobic effect, molecular recognition etc. Here we use a new approach to calculate translational and rotational entropy of the individual water molecules around different hydrophobic and charged solutes. We show that for small hydrophobic solutes, the translational and rotational entropies of each water molecule increase as a function of its distance from the solute reaching finally to a constant bulk value. As the size of the solute increases (0.746 nm), the behavior of the translational entropy is opposite; water molecules closest to the solute have higher entropy that reduces with distance from the solute. This indicates that there is a crossover in translational entropy of water molecules around hydrophobic solutes from negative to positive values as the size of the solute is increased. Rotational entropy of water molecules around hydrophobic solutes for all sizes increases with distance from the solute, indicating the absence of crossover in rotational entropy. This makes the crossover in total entropy (translation + rotation) of water molecule happen at much larger size (>1.5 nm) for hydrophobic solutes. Translational entropy of single water molecule scales logarithmically (Str(QH) = C + kB ln V), with the volume V obtained from the ellipsoid of inertia. We further discuss the origin of higher entropy of water around water and show the possibility of recovering the entropy loss of some hypothetical solutes. The results obtained are helpful to understand water entropy behavior around various hydrophobic and charged environments within biomolecules. Finally, we show how our approach can be used to calculate the entropy of the individual water molecules in a protein cavity that may be replaced during ligand binding.

  8. Classical to Quantum Crossover in Driven Josephson Junctions

    NASA Astrophysics Data System (ADS)

    Tian, C. S.; Kamenev, A.; Larkin, A. I.

    2004-03-01

    We consider the classical-quantum behavior crossover in a small, externally driven Josephson junction. Charge of a small superconducting grain fluctuates strongly if its critical current J_c(t) is modulated (kicked) by short periodic pulses (e.g. by changing the tunneling strength). The system may be mapped onto the model of quantum kicked rotator [1]. For large amplitudes of J_c(t) and short enough times, the grain charge, Q(t), diffuses in time. That is, the charge correlation function K(t) = <(Q(t)-Q(0))^2> = 2Dt, where the classical diffusion coefficient, D, may be expressed through the microscopical parameters of the model. Quantum corrections develop at times longer than the Ehrenfest time of the corresponding dynamical system, t_E ˜ ln D/(2e)^2. We have calculated weak-localization one-loop renormalization of the diffusion coefficient, δ D(ω), and found δ K(t)= -4/3√ π 2e√ D (t-2t_E)^3/2 for 2tE ˜ t≪ t_L, where t_L ˜ D/(2e)^2 is the time to develop the strong localization [1,2]. The predicted classical-quantum crossover may be observed by performing time-resolved potentiometry on the kicked Josephson grain. Alternatively, the effect may be detected by driving a periodic current of a large amplitude, J≫ J_c, across the grain and monitoring fluctuations of voltage. We believe that such a crossover applies to other periodic driven systems. [1] G. Casati et. al., Lect. Notes Phys.93, 334 (1979). [2] S.Fishman et. al. Phys. Rev. Lett. 49, 509 (1982); A.Altland, ibid. 71, 69 (1993).

  9. Crossover from anomalous to normal diffusion in porous media

    NASA Astrophysics Data System (ADS)

    Aarão Reis, F. D. A.; di Caprio, Dung

    2014-06-01

    Random walks (RW) of particles adsorbed in the internal walls of porous deposits produced by ballistic-type growth models are studied. The particles start at the external surface of the deposits and enter their pores in order to simulate an external flux of a species towards a porous solid. For short times, the walker concentration decays as a stretched exponential of the depth z, but a crossover to long-time normal diffusion is observed in most samples. The anomalous concentration profile remains at long times in very porous solids if the walker steps are restricted to nearest neighbors and is accompanied with subdiffusion features. These findings are correlated with a decay of the explored area with z. The study of RW of tracer particles left at the internal part of the solid rules out an interpretation by diffusion equations with position-dependent coefficients. A model of RW in a tube of decreasing cross section explains those results by showing long crossovers from an effective subdiffusion regime to an asymptotic normal diffusion. The crossover position and density are analytically calculated for a tube with area decreasing exponentially with z and show good agreement with numerical data. The anomalous decay of the concentration profile is interpreted as a templating effect of the tube shape on the total number of diffusing particles at each depth, while the volumetric concentration in the actually explored porous region may not have significant decay. These results may explain the anomalous diffusion of metal atoms in porous deposits observed in recent works. They also confirm the difficulty in interpreting experimental or computational data on anomalous transport reported in recent works, particularly if only the concentration profiles are measured.

  10. Apparent Temperature and Cause-Specific Mortality in Copenhagen, Denmark: A Case-Crossover Analysis

    PubMed Central

    Wichmann, Janine; Andersen, Zorana Jovanovic; Ketzel, Matthias; Ellermann, Thomas; Loft, Steffen

    2011-01-01

    Temperature, a key climate change indicator, is expected to increase substantially in the Northern Hemisphere, with potentially grave implications for human health. This study is the first to investigate the association between the daily 3-hour maximum apparent temperature (Tappmax), and respiratory, cardiovascular and cerebrovascular mortality in Copenhagen (1999–2006) using a case-crossover design. Susceptibility was investigated for age, sex, socio-economic status and place of death. For an inter-quartile range (7 °C) increase in Tappmax, an inverse association was found with cardiovascular mortality (−7% 95% CI −13%; −1%) and none with respiratory and cerebrovascular mortality. In the cold period all associations were inverse, although insignificant. PMID:22016711

  11. Air Pollution and Emergency Department Visits for Depression: A Multicity Case-Crossover Study

    PubMed Central

    Szyszkowicz, Mieczysław; Kousha, Termeh; Kingsbury, Mila; Colman, Ian

    2016-01-01

    BACKGROUND The aim of this study was to investigate the associations between ambient air pollution and emergency department (ED) visits for depression. METHODS Health data were retrieved from the National Ambulatory Care Reporting System. ED visits for depression were retrieved from the National Ambulatory Care Reporting System using the International Classification of Diseases (ICD-10), Tenth revision codes; ICD-10: F32 (mild depressive episode) and ICD-10: F33 (recurrent depressive disorder). A case-crossover design was employed for this study. Conditional logistic regression models were used to estimate odds ratios. RESULTS For females, exposure to ozone was associated with increased risk of an ED visit for depression between 1 and 7 days after exposure, for males, between 1 and 5, and 8 days after exposure, with odds ratios ranging between 1.02 and 1.03. CONCLUSIONS These findings suggest that, as hypothesized, there is a positive association between exposure to air pollution and ED visits for depression.

  12. 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.

  13. Randomised, double blind, crossover challenge study of allergenicity of peanut oils in subjects allergic to peanuts.

    PubMed Central

    Hourihane, J. O.; Bedwani, S. J.; Dean, T. P.; Warner, J. O.

    1997-01-01

    OBJECTIVE: To determine the in vivo allergenicity of two grades of peanut oil for a large group of subjects with proved allergy to peanuts. DESIGN: Double blind, crossover food challenge with crude peanut oil and refined peanut oil. SETTING: Dedicated clinical investigation unit in a university hospital. SUBJECTS: 60 subjects allergic to peanuts; allergy was confirmed by challenge tests. OUTCOME MEASURES: Allergic reaction to the tested peanut oils. RESULTS: None of the 60 subjects reacted to the refined oil; six (10%) reacted to the crude oil. Supervised peanut challenge caused considerably less severe reactions than subjects had reported previously. CONCLUSIONS: Crude peanut oil caused allergic reactions in 10% of allergic subjects studied and should continue to be avoided. Refined peanut oil did not pose a risk to any of the subjects. It would be reasonable to recommend a change in labelling to distinguish refined from crude peanut oil. PMID:9133891

  14. Meige syndrome: double-blind crossover study of sodium valproate.

    PubMed Central

    Snoek, J W; van Weerden, T W; Teelken, A W; van den Burg, W; Lakke, J P

    1987-01-01

    A double-blind crossover study of sodium valproate and placebo was conducted in five patients with Meige syndrome. CSF neurotransmitter studies were performed at the end of each treatment period. GABA levels were not influenced by the administration of sodium valproate. An increase in HVA levels was observed in every patient, which may reflect an increase in central dopaminergic activity. This finding may explain the trend towards clinical deterioration which was observed during treatment with sodium valproate. Sodium valproate appears to be ineffective in Meige syndrome. PMID:3121795

  15. Computational approach to the study of thermal spin crossover phenomena

    SciTech Connect

    Rudavskyi, Andrii; Broer, Ria; Sousa, Carmen

    2014-05-14

    The key parameters associated to the thermally induced spin crossover process have been calculated for a series of Fe(II) complexes with mono-, bi-, and tridentate ligands. Combination of density functional theory calculations for the geometries and for normal vibrational modes, and highly correlated wave function methods for the energies, allows us to accurately compute the entropy variation associated to the spin transition and the zero-point corrected energy difference between the low- and high-spin states. From these values, the transition temperature, T{sub 1/2}, is estimated for different compounds.

  16. Intrinsic DNA curvature of double-crossover tiles.

    PubMed

    Kim, Seungjae; Kim, Junghoon; Qian, Pengfei; Shin, Jihoon; Amin, Rashid; Ahn, Sang Jung; LaBean, Thomas H; Kim, Moon Ki; Park, Sung Ha

    2011-06-17

    A theoretical model which takes into account the structural distortion of double-crossover DNA tiles has been studied to investigate its effect on lattice formation sizes. It has been found that a single vector appropriately describes the curvature of the tiles, of which a higher magnitude hinders lattice growth. In conjunction with these calculations, normal mode analysis reveals that tiles with relative higher frequencies have an analogous effect. All the theoretical results are shown to be in good agreement with experimental data. PMID:21543827

  17. Spin Crossover in Ferropericlase from First-Principles Molecular Dynamics

    NASA Astrophysics Data System (ADS)

    Holmström, E.; Stixrude, L.

    2015-03-01

    Ferropericlase, (Mg,Fe)O, is the second-most abundant mineral of Earth's lower mantle. With increasing pressure, the Fe ions in the material begin to collapse from a magnetic to nonmagnetic spin state. We present a finite-temperature first-principles phase diagram of this spin crossover, finding a broad pressure range with coexisting magnetic and nonmagnetic ions due to favorable enthalpy of mixing of the two. Furthermore, we find the electrical conductivity of the mineral to reach semimetallic values inside Earth.

  18. Spin crossover in ferropericlase from first-principles molecular dynamics.

    PubMed

    Holmström, E; Stixrude, L

    2015-03-20

    Ferropericlase, (Mg,Fe)O, is the second-most abundant mineral of Earth's lower mantle. With increasing pressure, the Fe ions in the material begin to collapse from a magnetic to nonmagnetic spin state. We present a finite-temperature first-principles phase diagram of this spin crossover, finding a broad pressure range with coexisting magnetic and nonmagnetic ions due to favorable enthalpy of mixing of the two. Furthermore, we find the electrical conductivity of the mineral to reach semimetallic values inside Earth. PMID:25839305

  19. General schema theory for genetic programming with subtree-swapping crossover: Part II.

    PubMed

    Poli, Riccardo; McPhee, Nicholas Freitag

    2003-01-01

    This paper is the second part of a two-part paper which introduces a general schema theory for genetic programming (GP) with subtree-swapping crossover (Part I (Poli and McPhee, 2003)). Like other recent GP schema theory results, the theory gives an exact formulation (rather than a lower bound) for the expected number of instances of a schema at the next generation. The theory is based on a Cartesian node reference system, introduced in Part I, and on the notion of a variable-arity hyperschema, introduced here, which generalises previous definitions of a schema. The theory includes two main theorems describing the propagation of GP schemata: a microscopic and a macroscopic schema theorem. The microscopic version is applicable to crossover operators which replace a subtree in one parent with a subtree from the other parent to produce the offspring. Therefore, this theorem is applicable to Koza's GP crossover with and without uniform selection of the crossover points, as well as one-point crossover, size-fair crossover, strongly-typed GP crossover, context-preserving crossover and many others. The macroscopic version is applicable to crossover operators in which the probability of selecting any two crossover points in the parents depends only on the parents' size and shape. In the paper we provide examples, we show how the theory can be specialised to specific crossover operators and we illustrate how it can be used to derive other general results. These include an exact definition of effective fitness and a size-evolution equation for GP with subtree-swapping crossover.

  20. Juxtaposition of heterozygous and homozygous regions causes reciprocal crossover remodelling via interference during Arabidopsis meiosis

    PubMed Central

    Ziolkowski, Piotr A; Berchowitz, Luke E; Lambing, Christophe; Yelina, Nataliya E; Zhao, Xiaohui; Kelly, Krystyna A; Choi, Kyuha; Ziolkowska, Liliana; June, Viviana; Sanchez-Moran, Eugenio; Franklin, Chris; Copenhaver, Gregory P; Henderson, Ian R

    2015-01-01

    During meiosis homologous chromosomes undergo crossover recombination. Sequence differences between homologs can locally inhibit crossovers. Despite this, nucleotide diversity and population-scaled recombination are positively correlated in eukaryote genomes. To investigate interactions between heterozygosity and recombination we crossed Arabidopsis lines carrying fluorescent crossover reporters to 32 diverse accessions and observed hybrids with significantly higher and lower crossovers than homozygotes. Using recombinant populations derived from these crosses we observed that heterozygous regions increase crossovers when juxtaposed with homozygous regions, which reciprocally decrease. Total crossovers measured by chiasmata were unchanged when heterozygosity was varied, consistent with homeostatic control. We tested the effects of heterozygosity in mutants where the balance of interfering and non-interfering crossover repair is altered. Crossover remodeling at homozygosity-heterozygosity junctions requires interference, and non-interfering repair is inefficient in heterozygous regions. As a consequence, heterozygous regions show stronger crossover interference. Our findings reveal how varying homolog polymorphism patterns can shape meiotic recombination. DOI: http://dx.doi.org/10.7554/eLife.03708.001 PMID:25815584

  1. DNA methylation epigenetically silences crossover hot spots and controls chromosomal domains of meiotic recombination in Arabidopsis

    PubMed Central

    Yelina, Nataliya E.; Lambing, Christophe; Hardcastle, Thomas J.; Zhao, Xiaohui; Santos, Bruno; Henderson, Ian R.

    2015-01-01

    During meiosis, homologous chromosomes undergo crossover recombination, which is typically concentrated in narrow hot spots that are controlled by genetic and epigenetic information. Arabidopsis chromosomes are highly DNA methylated in the repetitive centromeres, which are also crossover-suppressed. Here we demonstrate that RNA-directed DNA methylation is sufficient to locally silence Arabidopsis euchromatic crossover hot spots and is associated with increased nucleosome density and H3K9me2. However, loss of CG DNA methylation maintenance in met1 triggers epigenetic crossover remodeling at the chromosome scale, with pericentromeric decreases and euchromatic increases in recombination. We used recombination mutants that alter interfering and noninterfering crossover repair pathways (fancm and zip4) to demonstrate that remodeling primarily involves redistribution of interfering crossovers. Using whole-genome bisulfite sequencing, we show that crossover remodeling is driven by loss of CG methylation within the centromeric regions. Using cytogenetics, we profiled meiotic DNA double-strand break (DSB) foci in met1 and found them unchanged relative to wild type. We propose that met1 chromosome structure is altered, causing centromere-proximal DSBs to be inhibited from maturation into interfering crossovers. These data demonstrate that DNA methylation is sufficient to silence crossover hot spots and plays a key role in establishing domains of meiotic recombination along chromosomes. PMID:26494791

  2. Crossover Interference on Nucleolus Organizing Region-Bearing Chromosomes in Arabidopsis

    PubMed Central

    Lam, Sandy Y.; Horn, Sarah R.; Radford, Sarah J.; Housworth, Elizabeth A.; Stahl, Franklin W.; Copenhaver, Gregory P.

    2005-01-01

    In most eukaryotes, crossovers are not independently distributed along the length of a chromosome. Instead, they appear to avoid close proximity to one another—a phenomenon known as crossover interference. Previously, for three of the five Arabidopsis chromosomes, we measured the strength of interference and suggested a model wherein some crossovers experience interference while others do not. Here we show, using the same model, that the fraction of interference-insensitive crossovers is significantly smaller on the remaining two chromosomes. Since these two chromosomes bear the Arabidopsis NOR domains, the possibility that these chromosomal regions influence interference is discussed. PMID:15802520

  3. Altimeter crossover methods for precision orbit determination and the mapping of geophysical parameters

    NASA Technical Reports Server (NTRS)

    Shum, C. K.; Schutz, B. E.; Tapley, B. D.; Zhang, B. H.

    1990-01-01

    Accurate orbit determination and the recovery of geophysical parameters are presently attempted via methodologies which use differenced height measurements at the points where the ground tracks of the altimetric satellite orbits intersect. Such 'crossover measurements' could significantly improve the earth's gravity field model. Attention is given to a novel technique employing crossover measurements from two satellites carrying altimeter instruments; this method can observe zonal harmonics of the earth's geopotential which are weakly observed through single-satellite crossovers. This dual-satellite crossover technique will be applicable to data from such future oceanographic satellites as ERS-1.

  4. High-Resolution Mapping of Crossover and Non-crossover Recombination Events by Whole-Genome Re-sequencing of an Avian Pedigree

    PubMed Central

    Qvarnström, Anna; Ellegren, Hans

    2016-01-01

    Recombination is an engine of genetic diversity and therefore constitutes a key process in evolutionary biology and genetics. While the outcome of crossover recombination can readily be detected as shuffled alleles by following the inheritance of markers in pedigreed families, the more precise location of both crossover and non-crossover recombination events has been difficult to pinpoint. As a consequence, we lack a detailed portrait of the recombination landscape for most organisms and knowledge on how this landscape impacts on sequence evolution at a local scale. To localize recombination events with high resolution in an avian system, we performed whole-genome re-sequencing at high coverage of a complete three-generation collared flycatcher pedigree. We identified 325 crossovers at a median resolution of 1.4 kb, with 86% of the events localized to <10 kb intervals. Observed crossover rates were in excellent agreement with data from linkage mapping, were 52% higher in male (3.56 cM/Mb) than in female meiosis (2.28 cM/Mb), and increased towards chromosome ends in male but not female meiosis. Crossover events were non-randomly distributed in the genome with several distinct hot-spots and a concentration to genic regions, with the highest density in promoters and CpG islands. We further identified 267 non-crossovers, whose location was significantly associated with crossover locations. We detected a significant transmission bias (0.18) in favour of ‘strong’ (G, C) over ‘weak’ (A, T) alleles at non-crossover events, providing direct evidence for the process of GC-biased gene conversion in an avian system. The approach taken in this study should be applicable to any species and would thereby help to provide a more comprehensive portray of the recombination landscape across organism groups. PMID:27219623

  5. Recombination patterns in maize reveal limits to crossover homeostasis.

    PubMed

    Sidhu, Gaganpreet K; Fang, Celestia; Olson, Mischa A; Falque, Matthieu; Martin, Olivier C; Pawlowski, Wojciech P

    2015-12-29

    During meiotic recombination, double-strand breaks (DSBs) are formed in chromosomal DNA and then repaired as either crossovers (COs) or non-crossovers (NCOs). In most taxa, the number of DSBs vastly exceeds the number of COs. COs are required for generating genetic diversity in the progeny, as well as proper chromosome segregation. Their formation is tightly controlled so that there is at least one CO per pair of homologous chromosomes whereas the maximum number of COs per chromosome pair is fairly limited. One of the main mechanisms controlling the number of recombination events per meiosis is CO homeostasis, which maintains a stable CO number even when the DSB number is dramatically altered. The existence of CO homeostasis has been reported in several species, including mouse, yeast, and Caenorhabditis elegans. However, it is not known whether homeostasis exists in the same form in all species. In addition, the studies of homeostasis have been conducted using mutants and/or transgenic lines exhibiting fairly severe meiotic phenotypes, and it is unclear how important homeostasis is under normal physiological conditions. We found that, in maize, CO control is robust only to ensure one CO per chromosome pair. However, once this limit is reached, the CO number is linearly related to the DSB number. We propose that CO control is a multifaceted process whose different aspects have a varying degree of importance in different species.

  6. Metal-to-insulator crossover in alkali doped zeolite.

    PubMed

    Igarashi, Mutsuo; Jeglič, Peter; Krajnc, Andraž; Žitko, Rok; Nakano, Takehito; Nozue, Yasuo; Arčon, Denis

    2016-01-01

    We report a systematic nuclear magnetic resonance investigation of the (23)Na spin-lattice relaxation rate, 1/T1, in sodium loaded low-silica X (LSX) zeolite, Nan/Na12-LSX, for various loading levels of sodium atoms n across the metal-to-insulator crossover. For high loading levels of n ≥ 14.2, 1/T1T shows nearly temperature-independent behaviour between 10 K and 25 K consistent with the Korringa relaxation mechanism and the metallic ground state. As the loading levels decrease below n ≤ 11.6, the extracted density of states (DOS) at the Fermi level sharply decreases, although a residual DOS at Fermi level is still observed even in the samples that lack the metallic Drude-peak in the optical reflectance. The observed crossover is a result of a complex loading-level dependence of electric potential felt by the electrons confined to zeolite cages, where the electronic correlations and disorder both play an important role.

  7. Observation of a crossover in kinetic aggregation of Palladium colloids

    NASA Astrophysics Data System (ADS)

    Ghafari, M.; Ranjbar, M.; Rouhani, S.

    2015-10-01

    We use field emission scanning electron microscope (FE-SEM) to investigate the growth of palladium colloids over the surface of thin films of WO3/glass. The film is prepared by Pulsed Laser Deposition (PLD) at different temperatures. A PdCl2 (aq) droplet is injected on the surface and in the presence of steam hydrogen the droplet is dried through a reduction reaction process. Two distinct aggregation regimes of palladium colloids are observed over the substrates. We argue that the change in aggregation dynamics emerges when the measured water drop Contact Angel (CA) for the WO3/glass thin films passes a certain threshold value, namely CA ≈ 46°, where a crossover in kinetic aggregation of palladium colloids occurs. Our results suggest that the mass fractal dimension of palladium aggregates follows a power-law behavior. The fractal dimension (Df) in the fast aggregation regime, where the measured CA values vary from 27° up to 46° according to different substrate deposition temperatures, is Df = 1.75(± 0.02) - the value of Df is in excellent agreement with kinetic aggregation of other colloidal systems in fast aggregation regime. Whereas for the slow aggregation regime, with CA = 58°, the fractal dimension changes abruptly to Df = 1.92(± 0.03). We have also used a modified Box-Counting method to calculate fractal dimension of gray-level images and observe that the crossover at around CA ≈ 46° remains unchanged.

  8. Recombination patterns in maize reveal limits to crossover homeostasis

    PubMed Central

    Sidhu, Gaganpreet K.; Fang, Celestia; Olson, Mischa A.; Falque, Matthieu; Martin, Olivier C.; Pawlowski, Wojciech P.

    2015-01-01

    During meiotic recombination, double-strand breaks (DSBs) are formed in chromosomal DNA and then repaired as either crossovers (COs) or non–crossovers (NCOs). In most taxa, the number of DSBs vastly exceeds the number of COs. COs are required for generating genetic diversity in the progeny, as well as proper chromosome segregation. Their formation is tightly controlled so that there is at least one CO per pair of homologous chromosomes whereas the maximum number of COs per chromosome pair is fairly limited. One of the main mechanisms controlling the number of recombination events per meiosis is CO homeostasis, which maintains a stable CO number even when the DSB number is dramatically altered. The existence of CO homeostasis has been reported in several species, including mouse, yeast, and Caenorhabditis elegans. However, it is not known whether homeostasis exists in the same form in all species. In addition, the studies of homeostasis have been conducted using mutants and/or transgenic lines exhibiting fairly severe meiotic phenotypes, and it is unclear how important homeostasis is under normal physiological conditions. We found that, in maize, CO control is robust only to ensure one CO per chromosome pair. However, once this limit is reached, the CO number is linearly related to the DSB number. We propose that CO control is a multifaceted process whose different aspects have a varying degree of importance in different species. PMID:26668366

  9. Dimensional crossover of a boson gas in multilayers

    SciTech Connect

    Salas, P.; Sevilla, F. J.; Fortes, M.; Solis, M. A.; Llano, M. de; Camacho, A.

    2010-09-15

    We obtain the thermodynamic properties for a noninteracting Bose gas constrained on multilayers modeled by a periodic Kronig-Penney delta potential in one direction and allowed to be free in the other two directions. We report Bose-Einstein condensation (BEC) critical temperatures, chemical potential, internal energy, specific heat, and entropy for different values of a dimensionless impenetrability P{>=}0 between layers. The BEC critical temperature T{sub c} coincides with the ideal gas BEC critical temperature T{sub 0} when P=0 and rapidly goes to zero as P increases to infinity for any finite interlayer separation. The specific heat C{sub V} as a function of absolute temperature T for finite P and plane separation a exhibits one minimum and one or two maxima in addition to the BEC, for temperatures larger than that of BEC T{sub c}. This highlights the effects due to particle confinement. We then discuss a distinctive dimensional crossover of the system through the specific heat behavior driven by the magnitude of P. For Tcrossover is revealed by a change in slope of logC{sub V}(T) and when T>T{sub c}, it is exhibited by a broad minimum in C{sub V}(T).

  10. Crossover Inhibition Generates Sustained Visual Responses in the Inner Retina

    PubMed Central

    Rosa, Juliana M.; Ruehle, Sabine; Ding, Huayu; Lagnado, Leon

    2016-01-01

    Summary In daylight, the input to the retinal circuit is provided primarily by cone photoreceptors acting as band-pass filters, but the retinal output also contains neuronal populations transmitting sustained signals. Using in vivo imaging of genetically encoded calcium reporters, we investigated the circuits that generate these sustained channels within the inner retina of zebrafish. In OFF bipolar cells, sustained transmission was found to depend on crossover inhibition from the ON pathway through GABAergic amacrine cells. In ON bipolar cells, the amplitude of low-frequency signals was regulated by glycinergic amacrine cells, while GABAergic inhibition regulated the gain of band-pass signals. We also provide the first functional description of a subset of sustained ON bipolar cells in which synaptic activity was suppressed by fluctuations at frequencies above ∼0.2 Hz. These results map out the basic circuitry by which the inner retina generates sustained visual signals and describes a new function of crossover inhibition. PMID:27068790

  11. Low Crossover Polymer Electrolyte Membranes for Direct Methanol Fuel Cells

    NASA Technical Reports Server (NTRS)

    Prakash, G. K. Surya; Smart, Marshall; Atti, Anthony R.; Olah, George A.; Narayanan, S. R.; Valdez, T.; Surampudi, S.

    1996-01-01

    Direct Methanol Fuel Cells (DMFC's) using polymer electrolyte membranes are promising power sources for portable and vehicular applications. State of the art technology using Nafion(R) 117 membranes (Dupont) are limited by high methanol permeability and cost, resulting in reduced fuel cell efficiencies and impractical commercialization. Therefore, much research in the fuel cell field is focused on the preparation and testing of low crossover and cost efficient polymer electrolyte membranes. The University of Southern California in cooperation with the Jet Propulsion Laboratory is focused on development of such materials. Interpenetrating polymer networks are an effective method used to blend polymer systems without forming chemical links. They provide the ability to modify physical and chemical properties of polymers by optimizing blend compositions. We have developed a novel interpenetrating polymer network based on poly (vinyl - difluoride)/cross-linked polystyrenesulfonic acid polymer composites (PVDF PSSA). Sulfonation of polystyrene accounts for protonic conductivity while the non-polar, PVDF backbone provides structural integrity in addition to methanol rejection. Precursor materials were prepared and analyzed to characterize membrane crystallinity, stability and degree of interpenetration. USC JPL PVDF-PSSA membranes were also characterized to determine methanol permeability, protonic conductivity and sulfur distribution. Membranes were fabricated into membrane electrode assemblies (MEA) and tested for single cell performance. Tests include cell performance over a wide range of temperatures (20 C - 90 C) and cathode conditions (ambient Air/O2). Methanol crossover values are measured in situ using an in-line CO2 analyzer.

  12. Bcs-Bec Crossover Without Appeal to Scattering Length Theory

    NASA Astrophysics Data System (ADS)

    Malik, G. P.

    2014-01-01

    BCS-BEC (an acronym formed from Bardeen, Cooper, Schrieffer and Bose-Einstein condensation) crossover physics has customarily been addressed in the framework of the scattering length theory (SLT), which requires regularization/renormalization of equations involving infinities. This paper gives a frame by frame picture, as it were, of the crossover scenario without appealing to SLT. While we believe that the intuitive approach followed here will make the subject accessible to a wider readership, we also show that it sheds light on a feature that has not been under the purview of the customary approach: the role of the hole-hole scatterings vis-à-vis the electron-electron scatterings as one goes from the BCS to the BEC end. More importantly, we show that there are critical values of the concentration (n)and the interaction parameter (λ) at which the condensation of Cooper pairs takes place; this is a finding in contrast with the view that such pairs are automatically condensed.

  13. Mechanistic studies of photoinduced spin crossover and electron transfer in inorganic complexes.

    PubMed

    Zhang, Wenkai; Gaffney, Kelly J

    2015-04-21

    numerous research groups with femtosecond resolution spectroscopy, but challenges in experimental interpretation have left significant uncertainty about the molecular properties that control these phenomena. Our Account will emphasize how tailoring the experimental probe, femtosecond resolution vibrational anisotropy for electron localization, and femtosecond resolution hard X-ray fluorescence for spin crossover can make a significant impact on the interpretability of experimental measurements. The emphasis on thorough and robust interpretation has also led to an emphasis on simpler molecular systems. This enables iteration between experiment and theory, a requirement for the development of a more predictive understanding of electronic excited-state phenomena and an essential step to the development of design rules for solar materials. PMID:25789406

  14. Salacia Extract Improves Postprandial Glucose and Insulin Response: A Randomized Double-Blind, Placebo Controlled, Crossover Study in Healthy Volunteers

    PubMed Central

    Jeykodi, Shankaranarayanan; Deshpande, Jayant

    2016-01-01

    Thirty-five healthy subjects were randomly assigned to different doses of Salacia chinensis extract (200 mg, 300 mg, and 500 mg SCE) capsules and compared with placebo. It is a placebo controlled randomized crossover design study. Subjects were given oral sucrose solution along with capsules and plasma glucose and insulin responses were analyzed. Blood samples were collected at 0, 30, 60, 90, 120, and 180 minutes after administration. AUC insulin significantly lowered after ingestion of SCE. No significant adverse events were observed. Reducing glucose and insulin is very important in reducing postprandial hyperglycemia. PMID:27803937

  15. Apparent temperature and acute myocardial infarction hospital admissions in Copenhagen, Denmark: a case-crossover study

    PubMed Central

    2012-01-01

    Background The influence of temperature on acute myocardial infarction (AMI) has not been investigated as extensively as the effects of broader outcomes of morbidity and mortality. Sixteen studies reported inconsistent results and two considered confounding by air pollution. We addressed some of the methodological limitations of the previous studies in this study. Methods This is the first study of the association between the daily 3-hour maximum apparent temperature (Tappmax) and AMI hospital admissions in Copenhagen. The study period covered 1 January 1999-31 December 2006, stratified in warm (April - September) and cold (October - March) periods. A case-crossover epidemiology study design was applied. Models were adjusted for public holidays and influenza, confounding by PM10, NO2 and CO was investigated, the lag and non-linear effects of Tappmax was examined, effect modification by age, sex and SES was explored, and the results of the case-crossover models were compared to those of the generalised additive Poisson time-series and generalised estimating equation models. Results 14 456 AMI hospital admissions (12 995 people) occurred during the study period. For an inter-quartile range (6 or 7°C) increase in the 5-day cumulative average of Tappmax, a 4% (95% CI:-2%; 10%) and 9% (95% CI: 3%; 14%) decrease in the AMI admission rate was observed in the warm and cold periods, respectively. The 19-65 year old group, men and highest SES group seemed to be more susceptible in the cold period. Conclusion An increase in Tappmax is associated with a decrease in AMI admissions during the colder months. PMID:22463704

  16. 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. PMID:27057878

  17. 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)…

  18. 49 CFR 218.107 - Additional operational requirements for hand-operated crossover switches.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Additional operational requirements for hand... hand-operated crossover switches. (a) Each railroad shall adopt and comply with an operating rule which... requirements of this section. (b) Hand-operated crossover switches, generally. Both hand-operated switches of...

  19. 49 CFR 218.107 - Additional operational requirements for hand-operated crossover switches.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Additional operational requirements for hand... hand-operated crossover switches. (a) Each railroad shall adopt and comply with an operating rule which... requirements of this section. (b) Hand-operated crossover switches, generally. Both hand-operated switches of...

  20. 49 CFR 218.103 - Hand-operated switches, including crossover switches.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Hand-operated switches, including crossover... Equipment, Switches, and Fixed Derails § 218.103 Hand-operated switches, including crossover switches. (a)(1...) General. Employees operating or verifying the position of a hand-operated switch shall: (1) Conduct...

  1. 49 CFR 218.107 - Additional operational requirements for hand-operated crossover switches.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Additional operational requirements for hand... hand-operated crossover switches. (a) Each railroad shall adopt and comply with an operating rule which... requirements of this section. (b) Hand-operated crossover switches, generally. Both hand-operated switches of...

  2. 49 CFR 218.103 - Hand-operated switches, including crossover switches.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Hand-operated switches, including crossover... Equipment, Switches, and Fixed Derails § 218.103 Hand-operated switches, including crossover switches. (a)(1...) General. Employees operating or verifying the position of a hand-operated switch shall: (1) Conduct...

  3. 49 CFR 218.107 - Additional operational requirements for hand-operated crossover switches.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Additional operational requirements for hand... hand-operated crossover switches. (a) Each railroad shall adopt and comply with an operating rule which... requirements of this section. (b) Hand-operated crossover switches, generally. Both hand-operated switches of...

  4. 49 CFR 218.103 - Hand-operated switches, including crossover switches.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Hand-operated switches, including crossover... Equipment, Switches, and Fixed Derails § 218.103 Hand-operated switches, including crossover switches. (a)(1...) General. Employees operating or verifying the position of a hand-operated switch shall: (1) Conduct...

  5. 49 CFR 218.103 - Hand-operated switches, including crossover switches.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Hand-operated switches, including crossover... Equipment, Switches, and Fixed Derails § 218.103 Hand-operated switches, including crossover switches. (a)(1...) General. Employees operating or verifying the position of a hand-operated switch shall: (1) Conduct...

  6. 49 CFR 218.107 - Additional operational requirements for hand-operated crossover switches.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Additional operational requirements for hand... hand-operated crossover switches. (a) Each railroad shall adopt and comply with an operating rule which... requirements of this section. (b) Hand-operated crossover switches, generally. Both hand-operated switches of...

  7. Reducing everyday memory and planning problems by means of a paging system: a randomised control crossover study

    PubMed Central

    Wilson, B; Emslie, H; Quirk, K; Evans, J

    2001-01-01

    OBJECTIVES—To evaluate a paging system designed to improve independence in people with memory problems and executive deficits.
METHODS—After a successful pilot study, a randomised control trial was conducted involving a crossover design with 143 people aged between 8 and 83 years. All had one or more of the following: memory, planning, attention, or organisation problems. Most had sustained a traumatic head injury or a stroke although a few had developmental learning difficulties or other conditions. The crossover design ensured that some people received a pager after a 2 week baseline whereas others were required to wait for 7 weeks after the baseline before receiving the pager. Participants were assessed at three time periods—namely, at baseline, 7 weeks, and at 14weeks postbaseline.
RESULTS—More than 80% of those who completed the 16 week trial were significantly more successful in carrying out everyday activities (such as self care, self medication, and keeping appointments) when using the pager in comparison with the baseline period. For most of these, significant improvement was maintained when they were monitored 7 weeks after returning the pager.
CONCLUSIONS—This particular paging system significantly reduces everyday failures of memory and planning in people with brain injury.

 PMID:11254770

  8. Evolution of a MCM complex in flies promoting meiotic crossovers by blocking BLM helicase

    PubMed Central

    Kohl, Kathryn P.; Jones, Corbin D.; Sekelsky, Jeff

    2013-01-01

    Generation of meiotic crossovers in many eukaryotes requires the elimination of anti-crossover activities by utilizing the Msh4–Msh5 heterodimer to block helicases. Msh4 and Msh5 have been lost from the flies Drosophila and Glossina but we identified a complex of mini-chromosome maintenance (MCM) proteins that functionally replace Msh4–Msh5. REC, an ortholog of MCM8 that evolved under strong positive selection in flies, interacts with MEI-217 and MEI-218, which arose from a previously undescribed metazoan-specific MCM protein. Meiotic crossovers are reduced in Drosophila rec, mei-217, and mei-218 mutants; however, removal of the Bloom syndrome helicase ortholog restores crossovers. Thus, MCMs were co-opted into a novel complex that replaces the meiotic pro-crossover function of Msh4–Msh5 in flies. PMID:23224558

  9. Unraveling the daily stress crossover between unemployed individuals and their employed spouses.

    PubMed

    Song, Zhaoli; Foo, Maw-Der; Uy, Marilyn A; Sun, Shuhua

    2011-01-01

    This study examined the dynamic relationship of distress levels between spouses when one is unemployed (and looking for a job) while the other is engaged in full-time employment. Using the diary survey method, we sampled 100 couples in China for 10 days and tested a model comprising three stress crossover mechanisms: the direct crossover, the mediating crossover, and the common stressor mechanisms. Results supported the direct crossover and common stressor mechanisms. Other stressors (e.g., work–family conflict and negative job search experience) were also related to distress of the unemployed individuals and their employed spouses. Additionally, we found a three-way interaction involving gender, marital satisfaction, and distress levels of employed spouses. We discuss how the study contributes to the unemployment and stress crossover literatures.

  10. Critical velocity in the BEC-BCS crossover.

    PubMed

    Weimer, Wolf; Morgener, Kai; Singh, Vijay Pal; Siegl, Jonas; Hueck, Klaus; Luick, Niclas; Mathey, Ludwig; Moritz, Henning

    2015-03-01

    We map out the critical velocity in the crossover from Bose-Einstein condensation to Bardeen-Cooper-Schrieffer superfluidity with ultracold ^{6}Li gases. A small attractive potential is dragged along lines of constant column density. The rate of the induced heating increases steeply above a critical velocity v_{c}. In the same samples, we measure the speed of sound v_{s} by exciting density waves and compare the results to the measured values of v_{c}. We perform numerical simulations in the Bose-Einstein condensation regime and find very good agreement, validating the approach. In the strongly correlated regime our measurements of v_{c} provide a testing ground for theoretical approaches.

  11. Metal-insulator crossover in multilayered MoS2.

    PubMed

    Park, Min Ji; Yi, Sum-Gyun; Kim, Joo Hyung; Yoo, Kyung-Hwa

    2015-10-01

    The temperature dependence of electrical transport properties was investigated for multilayered MoS2 field effect transistor devices with thicknesses of 3-22 nm. Some devices showed typical n-type semiconducting behavior, while others exhibited metal-insulator crossover (MIC) from metallic to insulating conduction at finite temperatures. The latter effect occurred near zero gate voltage or at high positive gate voltages. Analysis of Raman spectroscopy revealed the key difference that devices with MIC have a metallic 1T phase as well as a semiconducting 2H phase, whereas devices without the MIC did not have a metallic 1T phase. These results suggest that the metallic 1T phase may contribute to inducing the MIC.

  12. A crossover in anisotropic nanomechanochemistry of van der Waals crystals

    NASA Astrophysics Data System (ADS)

    Shimamura, Kohei; Misawa, Masaaki; Li, Ying; Kalia, Rajiv K.; Nakano, Aiichiro; Shimojo, Fuyuki; Vashishta, Priya

    2015-12-01

    In nanoscale mechanochemistry, mechanical forces selectively break covalent bonds to essentially control chemical reactions. An archetype is anisotropic detonation of layered energetic molecular crystals bonded by van der Waals (vdW) interactions. Here, quantum molecular dynamics simulations reveal a crossover of anisotropic nanomechanochemistry of vdW crystal. Within 10-13 s from the passage of shock front, lateral collision produces NO2 via twisting and bending of nitro-groups and the resulting inverse Jahn-Teller effect, which is mediated by strong intra-layer hydrogen bonds. Subsequently, as we transition from heterogeneous to homogeneous mechanochemical regimes around 10-12 s, shock normal to multilayers becomes more reactive, producing H2O assisted by inter-layer N-N bond formation. These time-resolved results provide much needed atomistic understanding of nanomechanochemistry that underlies a wider range of technologies.

  13. Experimental evidence for a dynamical crossover in liquid aluminium.

    PubMed

    Demmel, F; Fraile, A; Szubrin, D; Pilgrim, W-C; Morkel, C

    2015-11-18

    The temperature dependence of the dynamic structure factor at next-neighbour distances has been investigated for liquid aluminium. This correlation function is a sensitive parameter for changes in the local environment and its Fourier transform was measured in a coherent inelastic neutron scattering experiment. The zero frequency amplitude decreases in a nonlinear way and indicates a change in dynamics around 1.4 ∙ Tmelting. From that amplitude a generalized viscosity can be derived which is a measure of local stress correlations on next-neighbour distances. The derived generalized longitudinal viscosity shows a changing slope at the same temperature range. At this temperature the freezing out of degrees of freedom for structural relaxation upon cooling sets in which can be understood as a precursor towards the solid state. That crossover in dynamics of liquid aluminium shows the same signatures as previously observed in liquid rubidium and lead, indicating an universal character. PMID:26465204

  14. A crossover in anisotropic nanomechanochemistry of van der Waals crystals

    SciTech Connect

    Shimamura, Kohei; Misawa, Masaaki; Li, Ying; Kalia, Rajiv K.; Nakano, Aiichiro; Vashishta, Priya; Shimojo, Fuyuki

    2015-12-07

    In nanoscale mechanochemistry, mechanical forces selectively break covalent bonds to essentially control chemical reactions. An archetype is anisotropic detonation of layered energetic molecular crystals bonded by van der Waals (vdW) interactions. Here, quantum molecular dynamics simulations reveal a crossover of anisotropic nanomechanochemistry of vdW crystal. Within 10{sup −13} s from the passage of shock front, lateral collision produces NO{sub 2} via twisting and bending of nitro-groups and the resulting inverse Jahn-Teller effect, which is mediated by strong intra-layer hydrogen bonds. Subsequently, as we transition from heterogeneous to homogeneous mechanochemical regimes around 10{sup −12} s, shock normal to multilayers becomes more reactive, producing H{sub 2}O assisted by inter-layer N-N bond formation. These time-resolved results provide much needed atomistic understanding of nanomechanochemistry that underlies a wider range of technologies.

  15. Quantum corrections crossover and ferromagnetism in magnetic topological insulators.

    PubMed

    Bao, Lihong; Wang, Weiyi; Meyer, Nicholas; Liu, Yanwen; Zhang, Cheng; Wang, Kai; Ai, Ping; Xiu, Faxian

    2013-01-01

    Revelation of emerging exotic states of topological insulators (TIs) for future quantum computing applications relies on breaking time-reversal symmetry and opening a surface energy gap. Here, we report on the transport response of Bi2Te3 TI thin films in the presence of varying Cr dopants. By tracking the magnetoconductance (MC) in a low doping regime we observed a progressive crossover from weak antilocalization (WAL) to weak localization (WL) as the Cr concentration increases. In a high doping regime, however, increasing Cr concentration yields a monotonically enhanced anomalous Hall effect (AHE) accompanied by an increasing carrier density. Our results demonstrate a possibility of manipulating bulk ferromagnetism and quantum transport in magnetic TI, thus providing an alternative way for experimentally realizing exotic quantum states required by spintronic applications.

  16. Electrostatic spin crossover effect in polar magnetic molecules.

    PubMed

    Baadji, Nadjib; Piacenza, Manuel; Tugsuz, Tugba; Della Sala, Fabio; Maruccio, Giuseppe; Sanvito, Stefano

    2009-10-01

    The magnetic configuration of a nanostructure can be altered by an external magnetic field, by spin-transfer torque or by its magnetoelastic response. Here, we explore an alternative route, namely the possibility of switching the sign of the exchange coupling between two magnetic centres by means of an electric potential. This general effect, which we name electrostatic spin crossover, occurs in insulating molecules with super-exchange magnetic interaction and inversion symmetry breaking. As an example we present the case of a family of di-cobaltocene-based molecules. The critical fields for switching, calculated from first principles, are of the order of 1 V nm(-1) and can be achieved in two-terminal devices. More crucially, such critical fields can be engineered with an appropriate choice of substituents to add to the basic di-cobaltocene unit. This suggests that an easy chemical strategy for achieving the synthesis of suitable molecules is possible.

  17. Quantum Corrections Crossover and Ferromagnetism in Magnetic Topological Insulators

    PubMed Central

    Bao, Lihong; Wang, Weiyi; Meyer, Nicholas; Liu, Yanwen; Zhang, Cheng; Wang, Kai; Ai, Ping; Xiu, Faxian

    2013-01-01

    Revelation of emerging exotic states of topological insulators (TIs) for future quantum computing applications relies on breaking time-reversal symmetry and opening a surface energy gap. Here, we report on the transport response of Bi2Te3 TI thin films in the presence of varying Cr dopants. By tracking the magnetoconductance (MC) in a low doping regime we observed a progressive crossover from weak antilocalization (WAL) to weak localization (WL) as the Cr concentration increases. In a high doping regime, however, increasing Cr concentration yields a monotonically enhanced anomalous Hall effect (AHE) accompanied by an increasing carrier density. Our results demonstrate a possibility of manipulating bulk ferromagnetism and quantum transport in magnetic TI, thus providing an alternative way for experimentally realizing exotic quantum states required by spintronic applications. PMID:23928713

  18. Critical behavior and dimension crossover of pion superfluidity

    NASA Astrophysics Data System (ADS)

    Wang, Ziyue; Zhuang, Pengfei

    2016-09-01

    We investigate the critical behavior of pion superfluidity in the framework of the functional renormalization group (FRG). By solving the flow equations in the SU(2) linear sigma model at finite temperature and isospin density, and making comparison with the fixed point analysis of a general O (N ) system with continuous dimension, we find that the pion superfluidity is a second order phase transition subject to an O (2 ) universality class with a dimension crossover from dc=4 to dc=3 . This phenomenon provides a concrete example of dimension reduction in thermal field theory. The large-N expansion gives a temperature independent critical exponent β and agrees with the FRG result only at zero temperature.

  19. Critical velocity in the BEC-BCS crossover.

    PubMed

    Weimer, Wolf; Morgener, Kai; Singh, Vijay Pal; Siegl, Jonas; Hueck, Klaus; Luick, Niclas; Mathey, Ludwig; Moritz, Henning

    2015-03-01

    We map out the critical velocity in the crossover from Bose-Einstein condensation to Bardeen-Cooper-Schrieffer superfluidity with ultracold ^{6}Li gases. A small attractive potential is dragged along lines of constant column density. The rate of the induced heating increases steeply above a critical velocity v_{c}. In the same samples, we measure the speed of sound v_{s} by exciting density waves and compare the results to the measured values of v_{c}. We perform numerical simulations in the Bose-Einstein condensation regime and find very good agreement, validating the approach. In the strongly correlated regime our measurements of v_{c} provide a testing ground for theoretical approaches. PMID:25793823

  20. Crossover Phenomena in Detrended Fluctuation Analysis Used in Financial Markets

    NASA Astrophysics Data System (ADS)

    Ma, Shi-Hao

    2009-02-01

    A systematic analysis of Shanghai and Japan stock indices for the period of Jan. 1984 to Dec. 2005 is performed. After stationarity is verified by ADF (Augmented Dickey-Fuller) test, the power spectrum of the data exhibits a power law decay as a whole characterized by 1/fβ processes with possible long range correlations. Subsequently, by using the method of detrended fluctuation analysis (DFA) of the general volatility in the stock markets, we find that the long-range correlations are occurred among the return series and the crossover phenomena exhibit in the results obviously. Further, Shanghai stock market shows long-range correlations in short time scale and shows short-range correlations in long time scale. Whereas, for Japan stock market, the data behaves oppositely absolutely. Last, we compare the varying of scale exponent in large volatility between two stock markets. All results obtained may indicate the possibility of characteristic of multifractal scaling behavior of the financial markets.

  1. Escape from crossover interference increases with maternal age.

    PubMed

    Campbell, Christopher L; Furlotte, Nicholas A; Eriksson, Nick; Hinds, David; Auton, Adam

    2015-01-01

    Recombination plays a fundamental role in meiosis, ensuring the proper segregation of chromosomes and contributing to genetic diversity by generating novel combinations of alleles. Here, we use data derived from direct-to-consumer genetic testing to investigate patterns of recombination in over 4,200 families. Our analysis reveals a number of sex differences in the distribution of recombination. We find the fraction of male events occurring within hotspots to be 4.6% higher than for females. We confirm that the recombination rate increases with maternal age, while hotspot usage decreases, with no such effects observed in males. Finally, we show that the placement of female recombination events appears to become increasingly deregulated with maternal age, with an increasing fraction of events observed within closer proximity to each other than would be expected under simple models of crossover interference. PMID:25695863

  2. The crossover from single file to Fickian diffusion.

    PubMed

    Sané, Jimaan; Padding, Johan T; Louis, Ard A

    2010-01-01

    The crossover from single-file diffusion, where the mean-square displacement scales as (x2) to approximately t(1/2), to normal Fickian diffusion, where (x2) to approximately t, is studied as a function of channel width for colloidal particles. By comparing Brownian dynamics to a hybrid molecular dynamics and mesoscopic simulation technique, we can study the effect of hydrodynamic interactions on the single file mobility and on the crossover to Fickian diffusion for wider channel widths. For disc-like particles with a steep interparticle repulsion, the single file mobilities for different particle densities are well described by the exactly solvable hard-rod model. This holds both for simulations that include hydrodynamics, as well as for those that do not. When the single file constraint is lifted, then for particles of diameter sigma and pipe of width L such that (L - 2sigma)/sigma = deltac < 1, the particles can be described as hopping past one-another in an average time t(hop). For shorter times t < t(hop) the particles still exhibit sub-diffusive behaviour, but at longer times t > t(hop), normal Fickian diffusion sets in with an effective diffusion constant Dhop to approximately 1/ mean square root of t(hop). For the Brownian particles, t(hop) to approximately deltac(-2) when deltac < 1, but when hydrodynamic interactions are included, we find a stronger dependence than deltac(-2). We attribute this difference to short-range lubrication forces that make it more difficult for particles to hop past each other in very narrow channels.

  3. Relativistic description of BCS-BEC crossover in nuclear matter

    NASA Astrophysics Data System (ADS)

    Sun, Bao Yuan; Toki, Hiroshi; Meng, Jie

    2010-01-01

    We study theoretically the di-neutron spatial correlations and the crossover from superfluidity of neutron Cooper pairs in the S10 pairing channel to Bose-Einstein condensation (BEC) of di-neutron pairs for both symmetric and neutron matter in the microscopic relativistic pairing theory. We take the bare nucleon-nucleon interaction Bonn-B in the particle-particle channel and the effective interaction PK1 of the relativistic mean-field approach in the particle-hole channel. It is found that the spatial structure of neutron Cooper pair wave function evolves continuously from BCS-type to BEC-type as density decreases. We see a strong concentration of the probability density revealed for the neutron pairs in the fairly small relative distance around 1.5 fm and the neutron Fermi momentum kFn ∈ [ 0.6 , 1.0 ] fm-1. However, from the effective chemical potential and the quasiparticle excitation spectrum, there is no evidence for the appearance of a true BEC state of neutron pairs at any density. The most BEC-like state may appear at kFn ∼ 0.2 fm-1 by examining the density correlation function. From the coherence length and the probability distribution of neutron Cooper pairs as well as the ratio between the neutron pairing gap and the kinetic energy at the Fermi surface, some features of the BCS-BEC crossover are seen in the density regions, 0.05 fm-1

  4. Is Zolpidem Associated with Increased Risk of Fractures in the Elderly with Sleep Disorders? A Nationwide Case Cross-Over Study in Taiwan

    PubMed Central

    Chu, Fang-Ying; Chen, Hung-An; Yin, Yun-Ju; Lee, Hua-Chin; Chu, William Cheng-Chung; Yeh, Hui-Wen; Chiang, Wei-Shan; Yeh, Chia-Lun; Huang, Hui-Ling; Tzeng, Nian-Sheng

    2015-01-01

    Background We conducted a study using a case-crossover design to clarify the risk of acute effects of zolpidem and benzodiazepine on all-sites of fractures in the elderly. Design of study Case-crossover design. Methods and Materials Elderly enrollees (n = 6010) in Taiwan’s National Health Insurance Research Database with zolpidem or benzodiazepine use were analyzed for the risk of developing fractures. Results After adjusting for medications such as antipsychotics, antidepressants, and diuretics, or comorbidities such as hypertension, osteoarthritis, osteoporosis, rheumatoid arthritis and depression, neither zolpidem nor benzodiazepine was found to be associated with increased risk in all-sites fractures. Subjects without depression were found to have an increased risk of fractures. Diazepam is the only benzodiazepine with increased risk of fractures after adjusting for medications and comorbidities. Hip and spine were particular sites for increased fracture risk, but following adjustment for comorbidities, the associations were found to be insignificant. Conclusion Neither zolpidem nor benzodiazepine was associated with increased risk of all-site fractures in this case cross-over study after adjusting for medications or comorbidities in elderly individuals with insomnia. Clinicians should balance the benefits and risks for prescribing zolpidem or benzodiazepine in the elderly accordingly. PMID:26716836

  5. Crossover from the parity-conserving pair contact process with diffusion to other universality classes

    NASA Astrophysics Data System (ADS)

    Park, Su-Chan; Park, Hyunggyu

    2009-05-01

    The pair contact process with diffusion (PCPD) with modulo 2 conservation (PCPD2) [ 2A→4A , 2A→0 ] is studied in one dimension, focused on the crossover to other well established universality classes: the directed Ising (DI) and the directed percolation (DP). First, we show that the PCPD2 shares the critical behaviors with the PCPD, both with and without directional bias. Second, the crossover from the PCPD2 to the DI is studied by including a parity-conserving single-particle process (A→3A) . We find the crossover exponent 1/ϕ1=0.57(3) , which is argued to be identical to that of the PCPD-to-DP crossover by adding A→2A . This suggests that the PCPD universality class has a well-defined fixed point distinct from the DP. Third, we study the crossover from a hybrid-type reaction-diffusion process belonging to the DP [ 3A→5A , 2A→0 ] to the DI by adding A→3A . We find 1/ϕ2=0.73(4) for the DP-to-DI crossover. The inequality of ϕ1 and ϕ2 further supports the non-DP nature of the PCPD scaling. Finally, we introduce a symmetry-breaking field in the dual spin language to study the crossover from the PCPD2 to the DP. We find 1/ϕ3=1.23(10) , which is associated with a new independent route from the PCPD to the DP.

  6. A Pilot Study on Culottes versus Crossover Single Stenting for True Coronary Bifurcation Lesions

    PubMed Central

    Zhang, Linlin; Zhong, Wenliang; Luo, Yukun; Chen, Lianglong

    2016-01-01

    Background The purpose of our study was to compare clinical and angiographic outcomes of planned culottes technique with that of provisional crossover single stenting in the treatment of true coronary bifurcation lesions (CBL) with drug-eluting stent (DES). Methods True CBL patients (n = 104) were randomly assigned to either the provisional stenting of the side branch (crossover group) or the culottes group. Additional side branch (SB) stenting in the crossover group was required if there was thrombolysis in myocardial infarction flow ≤ 1 flow). The primary end point was the occurrence of major adverse cardiac events (MACE) at nine months, including cardiac death, myocardial infarction, target lesion/vessel revascularization and in-stent thrombosis. The secondary end point was angiographic in-segment restenosis at nine months. Results The rate of MACE at nine months was similar between the crossover and culottes groups (7.7% vs. 7.7%, p = 1.000). Additional SB stenting in the crossover group was required in 3.8% of patients. There was one procedural occlusion of SB in the crossover group. At nine months, the rate of in-segment restenosis was similar in the parent main vessel (0% vs. 1.9%, p = 1.000), main branch (1.9% vs. 7.7%, p = 0.363) and SB (17.3% vs. 9.6%, p = 0.250) between the crossover and culottes groups, respectively. Conclusions This study demonstrated that there is no significant difference in cumulative MACE or in-segment restenosis between crossover and culottes groups. Larger randomized clinical trials are warranted to re-evaluate the outcomes of the provisional crossover stenting versus the culottes stenting techniques utilizing DES for true CBL. PMID:27471358

  7. The effect of levetiracetam on focal nocturnal epileptiform activity during sleep--a placebo-controlled double-blind cross-over study.

    PubMed

    Larsson, Pål Gunnar; Bakke, Kristin A; Bjørnæs, Helge; Heminghyt, Einar; Rytter, Elisif; Brager-Larsen, Line; Eriksson, Ann-Sofie

    2012-05-01

    Electric Status Epilepticus during Sleep (ESES) occurs in children with and without epilepsy. It may be related to disturbances as autism spectrum disorder, attention-deficit hyperactivity disorder and acquired aphasia (Landau-Kleffner syndrome). Antiepileptic drug (AED) treatment has been reported in small studies without placebo control. This study was designed to assess AED effect in a placebo-controlled double-blind cross-over study. Levetiracetam (LEV) was chosen based on clinical evidence. Eighteen patients fulfilled the inclusion criteria. The mean spike index at baseline was 56, falling to a mean of 37 at the end of the LEV treatment period. Assessed with a 2-way ANOVA, there is a significant treatment effect (p<0.0002). To the best of our knowledge, this is the first placebo-controlled double-blind cross-over study for any AED in patients with ESES. The effect of LEV is comparable with its effect in treatment of epileptic seizures.

  8. Effects of a 30 kV/m, 60 Hz electric field on the social behavior of baboons: A crossover experiment

    SciTech Connect

    Easley, S.P.; Coelho, A.M. Jr.; Rogers, W.R. )

    1992-01-01

    Using a crossover experimental design, we evaluated our earlier findings that exposure to a 30 kV/m, 60 Hz electric field for 12 hours per day, 7 days per week for 6 weeks produced significant changes in the performance rates of social behaviors among young adult male baboons. In the crossover experiment, the former control group was exposed to a 30 kV/m, 60 Hz electric field for 3 weeks. Only an extremely small, incidental magnetic field was generated by the exposure apparatus. We found that electric-field exposure again produced increases in the performance rates that index Passive Affinity, Tension, and Stereotypy. These findings, combined with results from our other electric-field experiments, indicate that exposure to strong electric fields, in the absence of associated magnetic fields, consistently produces effects that are expressed as increases in rates of performance of social behaviors in young adult male baboons.

  9. Crossover from Classical to Quantum Kibble-Zurek Scaling

    NASA Astrophysics Data System (ADS)

    Silvi, Pietro; Morigi, Giovanna; Calarco, Tommaso; Montangero, Simone

    2016-06-01

    The Kibble-Zurek (KZ) hypothesis identifies the relevant time scales in out-of-equilibrium dynamics of critical systems employing concepts valid at equilibrium: It predicts the scaling of the defect formation immediately after quenches across classical and quantum phase transitions as a function of the quench speed. Here, we study the crossover between the scaling dictated by a slow quench, which is ruled by the critical properties of the quantum phase transition, and the excitations due to a faster quench, where the dynamics is often well described by the classical model. We estimate the value of the quench rate that separates the two regimes and support our argument using numerical simulations of the out-of-equilibrium many-body dynamics. For the specific case of a ϕ4 model we demonstrate that the two regimes exhibit two different power-law scalings, which are in agreement with the KZ theory when applied to the quantum and classical cases. This result contributes to extending the prediction power of the Kibble-Zurek mechanism and to providing insight into recent experimental observations in systems of cold atoms and ions.

  10. Crystallography and spin-crossover. A view of breathing materials.

    PubMed

    Guionneau, Philippe

    2014-01-14

    The spin-crossover phenomenon (SCO) is a fascinating field that potentially concerns any material containing a (d(4)-d(7)) transition metal complex finding therefore an echo in as diverse research fields as chemistry, physics, biology and geology. Particularly, molecular and coordination-polymers SCO solids are thoroughly investigated since their bistability promises new routes towards a large panel of potential applications including smart pigments, optical switches or memory devices. Notwithstanding these motivating applicative targets, numerous fundamental aspects of SCO are still debated. Among them, the investigation of the structure-property relationships is unfailingly at the heart of the SCO research field. All the facets of the richness of the structural behaviors shown by SCO compounds are only revealed when exploring the whole sample scales -from atomic to macroscopic- all the external stimuli-temperature, pressure, light and any combinations and derived perturbations- and the various forms of the SCO compounds in the solid state -crystalline powders, single-crystals, poorly crystalline or nano-sized particles. Crystallography allows investigating all these aspects of SCO solids. In the past few years, crystallography has certainly been in a significant phase of development pushing the frontiers of investigations, in particular thanks to the progress in X-ray diffraction techniques. The encounter between SCO materials and crystallography is captivating, taking advantages from each other. In this paper, a personal account mainly based on our recent results provides perspectives and new approaches that should be developed in the investigation of SCO materials.

  11. 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

  12. Flooding and Clostridium difficile Infection: A Case-Crossover Analysis.

    PubMed

    Lin, Cynthia J; Wade, Timothy J; Hilborn, Elizabeth D

    2015-06-01

    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.

  13. Air recirculation and sick building syndrome: a blinded crossover trial.

    PubMed Central

    Jaakkola, J J; Tuomaala, P; Seppänen, O

    1994-01-01

    OBJECTIVE. This study tested the hypothesis that recirculated air in mechanically ventilated buildings causes symptoms commonly referred to as the sick building syndrome and perceptions of poor indoor air quality. METHODS. A blinded, four-period crossover trial was carried out in two identical buildings, contrasting 70% return air (index phase) with 0% of return air (reference phase). Each period lasted 1 work-week. The study population comprised 75 workers who had reported symptoms related to the work environment or perceptions of poor indoor air quality. Participants reported their ratings of symptoms, their perceptions, and related information in a daily diary. The outcome criteria included aggregative symptom scores for mucosal irritation, skin reaction, allergic reaction, and general symptoms formed of ratings of component symptoms. Perceptions of unpleasant odor, stuffiness, or dustiness were additional outcome criteria. RESULTS. All 75 participants returned their diaries. For no symptoms did the scores differ between the two phases more than could be expected by chance. Mean rating of unpleasant odor was significantly smaller during the index phase, but mean ratings of dustiness and stuffiness did not differ materially between the two phases. CONCLUSIONS. Our results suggest that 70% recirculated air, when accompanied by an adequate intake of outdoor air, can be used without causing adverse effects. PMID:8129059

  14. Crossover from retro to specular Andreev reflections in bilayer graphene

    NASA Astrophysics Data System (ADS)

    Efetov, Dmitri K.; Efetov, Konstantin B.

    2016-08-01

    Ongoing experimental progress in the preparation of ultraclean graphene/superconductor (SC) interfaces enabled the recent observation of specular interband Andreev reflections (ARs) at bilayer graphene (BLG )/NbSe2 van der Waals interfaces [Efetov et al., Nat. Phys. 12, 328 (2016), 10.1038/nphys3583]. Motivated by this experiment we theoretically study the differential conductance across a BLG/SC interface at the continuous transition from high to ultralow Fermi energies EF in BLG. Using the Bogoliubov-de Gennes equations and the Blonder-Tinkham-Klapwijk formalism we derive analytical expressions for the differential conductance across the BLG/SC interface. We find a characteristic signature of the crossover from intraband retro (high EF) to interband specular (low EF) ARs that manifests itself in a strongly suppressed interfacial conductance when the excitation energy |ɛ |=| EF|<Δ (the SC gap). The sharpness of these conductance dips is strongly dependent on the size of the potential step at the BLG/SC interface U0.

  15. At grade optical crossover for monolithic optial circuits

    NASA Technical Reports Server (NTRS)

    Jamieson, Robert S. (Inventor)

    1983-01-01

    Planar optical circuits may be made to cross through each other, (thus eliminating extra steps required to fabricate elevated, nonintersecting crossovers) by control of the dimensions of the crossing light conductors (10, 12) to be significantly greater than d=0.89.lambda. and the angle of crossing as nearly 90.degree. as conveniently possible. A light trap may be provided just ahead of the intersection to trap any light being reflected in the source conductor at angles greater than about 45.degree.. The light trap may take the form of triangular shaped portions (16a, 16b) on each side of the source conductor with the far side of the triangular portion receiving incident light at an angle so that incident light will be reflected to the other side, or it may take the form of windows (18a, 18b) in place of the triangular portions. Planar optical circuit boards (21-23) may be fabricated and stacked to form a keyboard (20) with intersecting conductors (26-29) and keyholes (0-9) where conductors merge at the broad side of the circuit boards. These keyholes may be prearranged to form an array or matrix of keyholes.

  16. Tuning size and thermal hysteresis in bistable spin crossover nanoparticles.

    PubMed

    Galán-Mascarós, José Ramón; Coronado, Eugenio; Forment-Aliaga, Alicia; Monrabal-Capilla, María; Pinilla-Cienfuegos, Elena; Ceolin, Marcelo

    2010-06-21

    Nanoparticles of iron(II) triazole salts have been prepared from water-organic microemulsions. The mean size of the nanoparticles can be tuned down to 6 nm in diameter, with a narrow size distribution. A sharp spin transition from the low spin (LS) to the high spin (HS) state is observed above room temperature, with a 30-40-K-wide thermal hysteresis. The same preparation can yield second generation nanoparticles containing molecular alloys by mixing triazole with triazole derivatives, or from metallic mixtures of iron(II) and zinc(II). In these nanoparticles of 10-15 nm, the spin transition "moves" towards lower temperatures, reaching a 316 K limit for the cooling down transition and maintaining a thermal hysteresis over 15-20-K-wide. The nanoparticles were characterized by dynamic light scattering, TEM, and AFM, after deposition on gold or silicon surfaces. The spin transition was characterized by magnetic susceptibility measurements and EXAFS (in solid samples after solvent removal) and also by the color change between the LS (violet) and HS (colorless) states in an organic solvent suspension. The discovery of bistable magnetic nanoparticles of 6 nm with a wide thermal hysteresis above room temperature showcases the actual possibilities of spin crossover materials for nanotechnological applications. PMID:20503990

  17. 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.

  18. Quantum-to-classical crossover near quantum critical point

    PubMed Central

    Vasin, M.; Ryzhov, V.; Vinokur, V. M.

    2015-01-01

    A quantum phase transition (QPT) is an inherently dynamic phenomenon. However, while non-dissipative quantum dynamics is described in detail, the question, that is not thoroughly understood is how the omnipresent dissipative processes enter the critical dynamics near a quantum critical point (QCP). Here we report a general approach enabling inclusion of both adiabatic and dissipative processes into the critical dynamics on the same footing. We reveal three distinct critical modes, the adiabatic quantum mode (AQM), the dissipative classical mode [classical critical dynamics mode (CCDM)], and the dissipative quantum critical mode (DQCM). We find that as a result of the transition from the regime dominated by thermal fluctuations to that governed by the quantum ones, the system acquires effective dimension d + zΛ(T), where z is the dynamical exponent, and temperature-depending parameter Λ(T) ∈ [0, 1] decreases with the temperature such that Λ(T = 0) = 1 and Λ(T → ∞) = 0. Our findings lead to a unified picture of quantum critical phenomena including both dissipation- and dissipationless quantum dynamic effects and offer a quantitative description of the quantum-to-classical crossover. PMID:26688102

  19. Characterization of Non-Specific Crossover in SPLITT Fractionation

    PubMed Central

    Williams, P. Stephen; Hoyos, Mauricio; Kurowski, Pascal; Salhi, Dorra; Moore, Lee R.; Zborowski, Maciej

    2009-01-01

    Split-flow thin channel (SPLITT) fractionation is a technique for continuous separation of particles or macromolecules in a fluid stream into fractions according to the lateral migration induced by application of a field perpendicular to the direction of flow. Typical applications have involved isolation of different fractions from a polydisperse sample. Some specialized applications involve the separation of the fraction influenced by the transverse field from the fraction that is not. For example, immuno-magnetically labeled biological cells may be separated from non-labeled cells with the application of a transverse magnetic field gradient. In such cases, it may be critically important to minimize contamination of the labeled cells with non-labeled cells while at the same time maximizing the throughput. Such contamination is known as non-specific crossover (NSC) and refers to the real or apparent migration of non-mobile particles or cells across streamlines with the mobile material. The possible mechanisms for NSC are discussed, and experimental results interpreted in terms of shear-induced diffusion (SID) caused by viscous interactions between particles in a sheared flow. It is concluded that SID may contribute to NSC, but that further experiments and mathematical modeling are necessary to more fully explore the phenomenon. PMID:18698797

  20. Autotitrating versus standard noninvasive ventilation: a randomised crossover trial.

    PubMed

    Jaye, J; Chatwin, M; Dayer, M; Morrell, M J; Simonds, A K

    2009-03-01

    The aim of the present study was to compare the efficacy of automatic titration of noninvasive ventilation (NIV) with conventional NIV in stable neuromuscular and chest wall disorder patients established on long-term ventilatory support. In total, 20 neuromuscular and chest wall disease patients with nocturnal hypoventilation treated with long-term NIV completed a randomised crossover trial comparing two noninvasive pressure support ventilators: a standard bilevel ventilator (VPAP III) and a novel autotitrating bilevel ventilator (AutoVPAP). Baseline physiological measurements, overnight polysomnography and Holter monitoring were repeated at the end of each 1-month treatment period. Nocturnal oxygenation was comparable between the autotitrating device and standard ventilator, as were sleep efficiency, arousals and heart rate variability. However, there was a small significant increase in mean overnight transcutaneous carbon dioxide tension (median (interquartile range) 7.2 (6.7-7.7) versus 6.7 (6.1-7.0) kPa) and a decrease in percentage stage 1 sleep (mean+/-sd 16+/-9 versus 19+/-10%) on autotitrating NIV compared with conventional NIV. Autotitrating noninvasive ventilation using AutoVPAP produced comparable control of nocturnal oxygenation to standard nonivasive ventilation, without compromising sleep quality in stable neuromuscular and chest wall disease patients requiring long-term ventilatory support for nocturnal hypoventilation. PMID:19251798

  1. Quantum-to-classical crossover near quantum critical point

    SciTech Connect

    Vasin, M.; Ryzhov, V.; Vinokur, V. M.

    2015-12-21

    A quantum phase transition (QPT) is an inherently dynamic phenomenon. However, while non-dissipative quantum dynamics is described in detail, the question, that is not thoroughly understood is how the omnipresent dissipative processes enter the critical dynamics near a quantum critical point (QCP). Here we report a general approach enabling inclusion of both adiabatic and dissipative processes into the critical dynamics on the same footing. We reveal three distinct critical modes, the adiabatic quantum mode (AQM), the dissipative classical mode [classical critical dynamics mode (CCDM)], and the dissipative quantum critical mode (DQCM). We find that as a result of the transition from the regime dominated by thermal fluctuations to that governed by the quantum ones, the system acquires effective dimension d+zΛ(T), where z is the dynamical exponent, and temperature-depending parameter Λ(T)ε[0, 1] decreases with the temperature such that Λ(T=0) = 1 and Λ(T →∞) = 0. Lastly, our findings lead to a unified picture of quantum critical phenomena including both dissipation- and dissipationless quantum dynamic effects and offer a quantitative description of the quantum-to-classical crossover.

  2. Quantum-to-classical crossover near quantum critical point

    DOE PAGES

    Vasin, M.; Ryzhov, V.; Vinokur, V. M.

    2015-12-21

    A quantum phase transition (QPT) is an inherently dynamic phenomenon. However, while non-dissipative quantum dynamics is described in detail, the question, that is not thoroughly understood is how the omnipresent dissipative processes enter the critical dynamics near a quantum critical point (QCP). Here we report a general approach enabling inclusion of both adiabatic and dissipative processes into the critical dynamics on the same footing. We reveal three distinct critical modes, the adiabatic quantum mode (AQM), the dissipative classical mode [classical critical dynamics mode (CCDM)], and the dissipative quantum critical mode (DQCM). We find that as a result of the transitionmore » from the regime dominated by thermal fluctuations to that governed by the quantum ones, the system acquires effective dimension d+zΛ(T), where z is the dynamical exponent, and temperature-depending parameter Λ(T)ε[0, 1] decreases with the temperature such that Λ(T=0) = 1 and Λ(T →∞) = 0. Lastly, our findings lead to a unified picture of quantum critical phenomena including both dissipation- and dissipationless quantum dynamic effects and offer a quantitative description of the quantum-to-classical crossover.« less

  3. Crossover from Classical to Quantum Kibble-Zurek Scaling.

    PubMed

    Silvi, Pietro; Morigi, Giovanna; Calarco, Tommaso; Montangero, Simone

    2016-06-01

    The Kibble-Zurek (KZ) hypothesis identifies the relevant time scales in out-of-equilibrium dynamics of critical systems employing concepts valid at equilibrium: It predicts the scaling of the defect formation immediately after quenches across classical and quantum phase transitions as a function of the quench speed. Here, we study the crossover between the scaling dictated by a slow quench, which is ruled by the critical properties of the quantum phase transition, and the excitations due to a faster quench, where the dynamics is often well described by the classical model. We estimate the value of the quench rate that separates the two regimes and support our argument using numerical simulations of the out-of-equilibrium many-body dynamics. For the specific case of a ϕ^{4} model we demonstrate that the two regimes exhibit two different power-law scalings, which are in agreement with the KZ theory when applied to the quantum and classical cases. This result contributes to extending the prediction power of the Kibble-Zurek mechanism and to providing insight into recent experimental observations in systems of cold atoms and ions. PMID:27314729

  4. 49 CFR 236.203 - Hand operated crossover between main tracks; protection.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...) Facing point locks on both switches of the crossover, with both locks operated by a single lever, or (c... matter on the rail prevents effective shunting; (2) Where facing point locks with a single lever...

  5. 49 CFR 236.203 - Hand operated crossover between main tracks; protection.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...) Facing point locks on both switches of the crossover, with both locks operated by a single lever, or (c... matter on the rail prevents effective shunting; (2) Where facing point locks with a single lever...

  6. 49 CFR 236.203 - Hand operated crossover between main tracks; protection.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...) Facing point locks on both switches of the crossover, with both locks operated by a single lever, or (c... matter on the rail prevents effective shunting; (2) Where facing point locks with a single lever...

  7. Spin crossover in ferropericlase and velocity heterogeneities in the lower mantle.

    PubMed

    Wu, Zhongqing; Wentzcovitch, Renata M

    2014-07-22

    Deciphering the origin of seismic velocity heterogeneities in the mantle is crucial to understanding internal structures and processes at work in the Earth. The spin crossover in iron in ferropericlase (Fp), the second most abundant phase in the lower mantle, introduces unfamiliar effects on seismic velocities. First-principles calculations indicate that anticorrelation between shear velocity (VS) and bulk sound velocity (Vφ) in the mantle, usually interpreted as compositional heterogeneity, can also be produced in homogeneous aggregates containing Fp. The spin crossover also suppresses thermally induced heterogeneity in longitudinal velocity (VP) at certain depths but not in VS. This effect is observed in tomography models at conditions where the spin crossover in Fp is expected in the lower mantle. In addition, the one-of-a-kind signature of this spin crossover in the RS/P (∂ ln VS/∂ ln VP) heterogeneity ratio might be a useful fingerprint to detect the presence of Fp in the lower mantle. PMID:25002507

  8. Direct observation in 3d of structural crossover in binary hard sphere mixtures

    NASA Astrophysics Data System (ADS)

    Statt, Antonia; Pinchaipat, Rattachai; Turci, Francesco; Evans, Robert; Royall, C. Patrick

    2016-04-01

    For binary fluid mixtures of spherical particles in which the two species are sufficiently different in size, the dominant wavelength of oscillations of the pair correlation functions is predicted to change from roughly the diameter of the large species to that of the small species along a sharp crossover line in the phase diagram [C. Grodon et al., J. Chem. Phys. 121, 7869 (2004)]. Using particle-resolved colloid experiments in 3d we demonstrate that crossover exists and that its location in the phase diagram is in quantitative agreement with the results of both theory and our Monte-Carlo simulations. In contrast with previous work [J. Baumgartl et al., Phys. Rev. Lett. 98, 198303 (2007)], where a correspondence was drawn between crossover and percolation of both species, in our 3d study we find that structural crossover is unrelated to percolation.

  9. Relativistic BCS-BEC crossover in a boson-fermion model

    SciTech Connect

    Deng Jian; Wang Qun; Schmitt, Andreas

    2007-08-01

    We investigate the crossover from Bardeen-Cooper-Schrieffer (BCS) pairing to a Bose-Einstein condensate (BEC) in a relativistic superfluid within a boson-fermion model. The model includes, besides the fermions, separate bosonic degrees of freedom, accounting for the bosonic nature of the Cooper pairs. The crossover is realized by tuning the difference between the boson mass and boson chemical potential as a free parameter. The model yields populations of condensed and uncondensed bosons as well as gapped and ungapped fermions throughout the crossover region for arbitrary temperatures. Moreover, we observe the appearance of antiparticles for sufficiently large values of the crossover parameter. As an application, we study pairing of fermions with imbalanced populations. The model can potentially be applied to color superconductivity in dense quark matter at strong couplings.

  10. 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.

  11. 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

  12. Precise Determination of the Direct-Indirect Band Gap Energy Crossover In AlxGa1-xAs

    NASA Astrophysics Data System (ADS)

    Fluegel, Brian; Beaton, Daniel; Alberi, Kirstin; Mascarenhas, Angelo

    2014-03-01

    AlxGa1-xAs is a technologically important semiconductor material system for optoelectronic applications due to its type I band alignment with GaAs under nearly lattice-matched conditions. Heterostructure design often relies on exactly controlling the relative positions of the Γ and X conduction band edges, yet despite over three decades of research on this alloy, the precise energy and composition of the direct-indirect band gap crossover is still not well resolved. We report the results of our most recent investigation of AlxGa1-xAs (0.28 < x<0.42) epitaxial films, in which the observation of concurrent photoluminescence (PL) emission peaks from the direct and indirect band gaps combined with time-resolved PL information yields a precise determination of the direct-indirect band gap crossover energy and composition. This work was supported by the DOE Office of Science, Basic Energy Sciences under contract DE-AC36-08GO28308. Acknowledgement: the samples were provided by John Reno from Sandia National Laboratory.

  13. Separable Roles for a Caenorhabditis elegans RMI1 Homolog in Promoting and Antagonizing Meiotic Crossovers Ensure Faithful Chromosome Inheritance.

    PubMed

    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

    2016-03-01

    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.

  14. 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.

  15. Splitter imperfections in annular split-flow thin separation channels: experimental study of nonspecific crossover.

    PubMed

    Williams, P Stephen; Decker, Keith; Nakamura, Masayuki; Chalmers, Jeffrey J; Moore, Lee R; Zborowski, Maciej

    2003-12-01

    The separation performance of a split-flow thin (SPLITT) separation device depends on uniformity of channel thickness and the precise placement of the flow splitters at fixed distances between the channel walls. The observation of nonspecific crossover, that is, the transport of sample materials across the channel thickness without the influence of an applied field, has routinely been taken to indicate the presence of irregularities in splitter shape or placement. Computational fluid dynamics software may be used to predict the influence of splitter imperfections on nonspecific crossover, where it is assumed that sample transport is by convection alone. A previous study has shown how small inlet splitter imperfections can account for the relatively low levels of nonspecific crossover observed with typical annular SPLITT devices. This study, however, could not distinguish between the possible sources of nonspecific crossover; hydrodynamic lift or shear-induced diffusion could have contributed. To confirm the validity of the computational approach, a series of experiments has been carried out on a channel having a deliberately and severely bent splitter. Nonspecific crossover was measured for a range of inlet and outlet flow rate ratios, with the bent splitter placed at both the channel inlet and outlet. The severity of the splitter distortion was sufficient to produce significant nonspecific crossover over a wide range of flow conditions. Good agreement was found between experiment and prediction based on computational fluid dynamics, with experiment generally showing only slightly higher crossover than prediction. The quantitative agreement for this extreme case suggests that the contribution to nonspecific crossover due to geometrical imperfections can be well described using computational fluid dynamics. PMID:14640746

  16. Analysis of Crossovers in the Interbeat Sequences of Elderly Individuals and Heart Failure Patients

    NASA Astrophysics Data System (ADS)

    Muñoz-Diosdado, A.; del Río Correa, J. L.

    2006-09-01

    Many physical and biological systems exhibit complex behavior characterized by long-range power-law correlations. Detrended fluctuation analysis (DFA) is a scaling analysis method that provides a scaling parameter to represent the correlation properties of a signal. The study of interbeat sequences with the DFA method has revealed the presence of crossovers associated with physiological aging and heart with failure; the hinges present in the crossover region from both the elderly healthy individuals and the patients with congestive heart failure (CHF) are in opposite directions. The interbeat sequences of healthy young persons do not show crossovers. In this paper we study interbeat time series of healthy young and elderly persons and patients with CHF. We use the DFA-m method, where m refers to the order of the polynomial function used for the fitting. For instance, DFA-2 filters linear trends and DFA-3 filters quadratic trends. We found that the presence of the crossovers and the direction of the hinges are conserved when we apply the DFA method for different values of m. Therefore we conclude that the DFA-m method is a reliable method to accurately quantify correlations in interbeat time series even if there are polynomial trends. We can characterize the crossovers and we can conclude that the crossovers are not a result of the trends; they are part of the system dynamics.

  17. Crossover behavior of the thermal conductance and Kramers’ transition rate theory

    PubMed Central

    Velizhanin, Kirill A.; Sahu, Subin; Chien, Chih-Chun; Dubi, Yonatan; Zwolak, Michael

    2015-01-01

    Kramers’ theory frames chemical reaction rates in solution as reactants overcoming a barrier in the presence of friction and noise. For weak coupling to the solution, the reaction rate is limited by the rate at which the solution can restore equilibrium after a subset of reactants have surmounted the barrier to become products. For strong coupling, there are always sufficiently energetic reactants. However, the solution returns many of the intermediate states back to the reactants before the product fully forms. Here, we demonstrate that the thermal conductance displays an analogous physical response to the friction and noise that drive the heat current through a material or structure. A crossover behavior emerges where the thermal reservoirs dominate the conductance at the extremes and only in the intermediate region are the intrinsic properties of the lattice manifest. Not only does this shed new light on Kramers’ classic turnover problem, this result is significant for the design of devices for thermal management and other applications, as well as the proper simulation of transport at the nanoscale. PMID:26634333

  18. Acute Effects of a Spinach Extract Rich in Thylakoids on Satiety: A Randomized Controlled Crossover Trial

    PubMed Central

    Rebello, Candida J.; Chu, Jessica; Beyl, Robbie; Edwall, Dan; Erlanson-Albertsson, Charlotte; Greenway, Frank L.

    2015-01-01

    Objective: By retarding fat digestion, thylakoids, the internal photosynthetic membrane system of green plants, promote the release of satiety hormones. This study examined the effect of consuming a single dose of concentrated extract of thylakoids from spinach on satiety, food intake, lipids, and glucose compared to a placebo. Design: Sixty overweight and obese individuals enrolled in a double-blind randomized crossover study consumed the spinach extract or placebo in random order at least a week apart. Blood was drawn for assessments of lipids and glucose before a standard breakfast meal, followed 4 hours later by a 5 g dose of the extract and a standard lunch. Visual analog scales were administered before lunch and at intervals until an ad libitum pizza dinner served 4 hours later. Two hours after lunch a second blood draw was conducted. Mixed models were used to analyze response changes. Results: Compared to placebo, consuming the spinach extract reduced hunger (p < 0.01) and longing for food over 2 hours (p < 0.01) and increased postprandial plasma glucose concentrations (p < 0.01). There were no differences in plasma lipids and energy intake at dinner, but males showed a trend toward decreased energy intake (p = 0.08). Conclusions: At this dose, the spinach extract containing thylakoids increases satiety over a 2-hour period compared to a placebo. Thylakoid consumption may influence gender-specific food cravings. PMID:26029978

  19. On the zeroth-order hamiltonian for CASPT2 calculations of spin crossover compounds.

    PubMed

    Vela, Sergi; Fumanal, Maria; Ribas-Ariño, Jordi; Robert, Vincent

    2016-04-15

    Complete active space self-consistent field theory (CASSCF) calculations and subsequent second-order perturbation theory treatment (CASPT2) are discussed in the evaluation of the spin-states energy difference (ΔH(elec)) of a series of seven spin crossover (SCO) compounds. The reference values have been extracted from a combination of experimental measurements and DFT + U calculations, as discussed in a recent article (Vela et al., Phys Chem Chem Phys 2015, 17, 16306). It is definitely proven that the critical IPEA parameter used in CASPT2 calculations of ΔH(elec), a key parameter in the design of SCO compounds, should be modified with respect to its default value of 0.25 a.u. and increased up to 0.50 a.u. The satisfactory agreement observed previously in the literature might result from an error cancellation originated in the default IPEA, which overestimates the stability of the HS state, and the erroneous atomic orbital basis set contraction of carbon atoms, which stabilizes the LS states.

  20. Cytopathology whole slide images and adaptive tutorials for postgraduate pathology trainees: a randomized crossover trial.

    PubMed

    Van Es, Simone L; Kumar, Rakesh K; Pryor, Wendy M; Salisbury, Elizabeth L; Velan, Gary M

    2015-09-01

    To determine whether cytopathology whole slide images and virtual microscopy adaptive tutorials aid learning by postgraduate trainees, we designed a randomized crossover trial to evaluate the quantitative and qualitative impact of whole slide images and virtual microscopy adaptive tutorials compared with traditional glass slide and textbook methods of learning cytopathology. Forty-three anatomical pathology registrars were recruited from Australia, New Zealand, and Malaysia. Online assessments were used to determine efficacy, whereas user experience and perceptions of efficiency were evaluated using online Likert scales and open-ended questions. Outcomes of online assessments indicated that, with respect to performance, learning with whole slide images and virtual microscopy adaptive tutorials was equivalent to using traditional methods. High-impact learning, efficiency, and equity of learning from virtual microscopy adaptive tutorials were strong themes identified in open-ended responses. Participants raised concern about the lack of z-axis capability in the cytopathology whole slide images, suggesting that delivery of z-stacked whole slide images online may be important for future educational development. In this trial, learning cytopathology with whole slide images and virtual microscopy adaptive tutorials was found to be as effective as and perceived as more efficient than learning from glass slides and textbooks. The use of whole slide images and virtual microscopy adaptive tutorials has the potential to provide equitable access to effective learning from teaching material of consistently high quality. It also has broader implications for continuing professional development and maintenance of competence and quality assurance in specialist practice.

  1. Air Pollution and Emergency Department Visits for Depression: A Multicity Case-Crossover Study

    PubMed Central

    Szyszkowicz, Mieczysław; Kousha, Termeh; Kingsbury, Mila; Colman, Ian

    2016-01-01

    BACKGROUND The aim of this study was to investigate the associations between ambient air pollution and emergency department (ED) visits for depression. METHODS Health data were retrieved from the National Ambulatory Care Reporting System. ED visits for depression were retrieved from the National Ambulatory Care Reporting System using the International Classification of Diseases (ICD-10), Tenth revision codes; ICD-10: F32 (mild depressive episode) and ICD-10: F33 (recurrent depressive disorder). A case-crossover design was employed for this study. Conditional logistic regression models were used to estimate odds ratios. RESULTS For females, exposure to ozone was associated with increased risk of an ED visit for depression between 1 and 7 days after exposure, for males, between 1 and 5, and 8 days after exposure, with odds ratios ranging between 1.02 and 1.03. CONCLUSIONS These findings suggest that, as hypothesized, there is a positive association between exposure to air pollution and ED visits for depression. PMID:27597809

  2. Melatonin reduces tachycardia in Postural Tachycardia Syndrome (POTS): A Randomized, Crossover Trial

    PubMed Central

    Green, Elizabeth A; Black, Bonnie K; Biaggioni, Italo; Paranjape, Sachin Y; Bagai, Kanika; Shibao, Cyndya; Okoye, Miriam C; Dupont, William D.; Robertson, David; Raj, Satish R

    2014-01-01

    Background Postural Tachycardia Syndrome (POTS) induces disabling chronic orthostatic intolerance with an excessive increase in heart rate (HR) upon standing, and many POTS patients have a hyperadrenergic state. Medications that restrain HR are a promising approach to this problem. Objective We tested the hypothesis that melatonin will attenuate the tachycardia and improve symptom burden in patients with POTS. Methods Patients with POTS (n=78) underwent acute drug trials with melatonin 3 mg orally and placebo, on separate mornings, in a randomized crossover design. Blood pressure, HR and symptoms were assessed while seated and after standing for up to 10 minutes prior to, and hourly for 4 hours following, study drug administration. Results The reduction in standing HR was significantly greater two hours after melatonin compared to placebo (P=0.017). There was no significant difference in the reduction of systolic blood pressure between melatonin and placebo, either with standing or while seated. The symptom burden was not improved with melatonin compared with placebo. Conclusion Oral melatonin produced a modest decrease in standing tachycardia in POTS. Further research is needed to determine the effects of regular night-time use of this medication in POTS. PMID:24495468

  3. Phenomenological model of spin crossover in molecular crystals as derived from atom-atom potentials.

    PubMed

    Sinitskiy, Anton V; Tchougréeff, Andrei L; Dronskowski, Richard

    2011-08-01

    The method of atom-atom potentials, previously applied to the analysis of pure molecular crystals formed by either low-spin (LS) or high-spin (HS) forms (spin isomers) of Fe(II) coordination compounds (Sinitskiy et al., Phys. Chem. Chem. Phys., 2009, 11, 10983), is used to estimate the lattice enthalpies of mixed crystals containing different fractions of the spin isomers. The crystals under study were formed by LS and HS isomers of Fe(phen)(2)(NCS)(2) (phen = 1,10-phenanthroline), Fe(btz)(2)(NCS)(2) (btz = 5,5',6,6'-tetrahydro-4H,4'H-2,2'-bi-1,3-thiazine), and Fe(bpz)(2)(bipy) (bpz = dihydrobis(1-pyrazolil)borate, and bipy = 2,2'-bipyridine). For the first time the phenomenological parameters Γ pertinent to the Slichter-Drickamer model (SDM) of several materials were independently derived from the microscopic model of the crystals with use of atom-atom potentials of intermolecular interaction. The accuracy of the SDM was checked against the numerical data on the enthalpies of mixed crystals. Fair semiquantitative agreement with the experimental dependence of the HS fraction on temperature was achieved with use of these values. Prediction of trends in Γ values as a function of chemical composition and geometry of the crystals is possible with the proposed approach, which opens a way to rational design of spin crossover materials with desired properties.

  4. Crossover behavior of the thermal conductance and Kramers’ transition rate theory

    SciTech Connect

    Velizhanin, Kirill A.; Sahu, Subin; Chien, Chih -Chun; Dubi, Yonatan; Zwolak, Michael

    2015-12-04

    Kramers’ theory frames chemical reaction rates in solution as reactants overcoming a barrier in the presence of friction and noise. For weak coupling to the solution, the reaction rate is limited by the rate at which the solution can restore equilibrium after a subset of reactants have surmounted the barrier to become products. For strong coupling, there are always sufficiently energetic reactants. However, the solution returns many of the intermediate states back to the reactants before the product fully forms. Here, we demonstrate that the thermal conductance displays an analogous physical response to the friction and noise that drive the heat current through a material or structure. A crossover behavior emerges where the thermal reservoirs dominate the conductance at the extremes and only in the intermediate region are the intrinsic properties of the lattice manifest. Finally, not only does this shed new light on Kramers’ classic turnover problem, this result is significant for the design of devices for thermal management and other applications, as well as the proper simulation of transport at the nanoscale.

  5. Synthetic food colourings and 'hyperactivity': a double-blind crossover study.

    PubMed

    Rowe, K S

    1988-04-01

    Of 220 children referred for suspected 'hyperactivity', 55 were subjected to a 6 week trial of the Feingold diet. Forty (72.7%) demonstrated improved behaviour and 26 (47.3%) remained improved following liberalization of the diet over a period of 3-6 months. The parents of 14 children claimed that a particular cluster of behaviours was associated with the ingestion of foods containing synthetic colourings. A double-blind crossover study, employing a single-subject repeated measures design was conducted, using eight of these children. Subjects were maintained on a diet free from synthetic additives and were challenged daily for 18 weeks with either placebo (during lead-in and washout periods) or 50 mg of either tartrazine or carmoisine, each for 2 separate weeks. Two significant reactors were identified whose behavioural pattern featured extreme irritability, restlessness and sleep disturbance. One of the reactors did not have inattention as a feature. The findings raise the issue of whether the strict criteria for inclusion in studies concerned with 'hyperactivity' based on 'attention deficit disorder' may miss children who indicate behavioural changes associated with the ingestion of food colourings. Moreover, for further studies, the need to construct a behavioural rating instrument specifically validated for dye challenge is suggested.

  6. Crossover behavior of the thermal conductance and Kramers' transition rate theory.

    PubMed

    Velizhanin, Kirill A; Sahu, Subin; Chien, Chih-Chun; Dubi, Yonatan; Zwolak, Michael

    2015-01-01

    Kramers' theory frames chemical reaction rates in solution as reactants overcoming a barrier in the presence of friction and noise. For weak coupling to the solution, the reaction rate is limited by the rate at which the solution can restore equilibrium after a subset of reactants have surmounted the barrier to become products. For strong coupling, there are always sufficiently energetic reactants. However, the solution returns many of the intermediate states back to the reactants before the product fully forms. Here, we demonstrate that the thermal conductance displays an analogous physical response to the friction and noise that drive the heat current through a material or structure. A crossover behavior emerges where the thermal reservoirs dominate the conductance at the extremes and only in the intermediate region are the intrinsic properties of the lattice manifest. Not only does this shed new light on Kramers' classic turnover problem, this result is significant for the design of devices for thermal management and other applications, as well as the proper simulation of transport at the nanoscale. PMID:26634333

  7. Crossover behavior of the thermal conductance and Kramers’ transition rate theory

    DOE PAGES

    Velizhanin, Kirill A.; Sahu, Subin; Chien, Chih -Chun; Dubi, Yonatan; Zwolak, Michael

    2015-12-04

    Kramers’ theory frames chemical reaction rates in solution as reactants overcoming a barrier in the presence of friction and noise. For weak coupling to the solution, the reaction rate is limited by the rate at which the solution can restore equilibrium after a subset of reactants have surmounted the barrier to become products. For strong coupling, there are always sufficiently energetic reactants. However, the solution returns many of the intermediate states back to the reactants before the product fully forms. Here, we demonstrate that the thermal conductance displays an analogous physical response to the friction and noise that drive themore » heat current through a material or structure. A crossover behavior emerges where the thermal reservoirs dominate the conductance at the extremes and only in the intermediate region are the intrinsic properties of the lattice manifest. Finally, not only does this shed new light on Kramers’ classic turnover problem, this result is significant for the design of devices for thermal management and other applications, as well as the proper simulation of transport at the nanoscale.« less

  8. Neckties and Cerebrovascular Reactivity in Young Healthy Males: A Pilot Randomised Crossover Trial

    PubMed Central

    Rafferty, Mark; Quinn, Terence J.; Dawson, Jesse; Walters, Matthew

    2011-01-01

    Background. A necktie may elevate intracranial pressure through compression of venous return. We hypothesised that a tight necktie would deleteriously alter cerebrovascular reactivity. Materials and Methods. A necktie was simulated using bespoke apparatus comprising pneumatic inner-tube with aneroid pressure-gauge. Using a randomised crossover design, cerebrovascular reactivity was measured with the “pseudo-tie” worn inflated or deflated for 5 minutes (simulating tight/loose necktie resp.). Reactivity was calculated using breath hold index (BHI) and paired “t” testing used for comparative analysis. Results. We enrolled 40 healthy male volunteers. There was a reduction in cerebrovascular reactivity of 0.23 units with “tight” pseudotie (BHI loose 1.44 (SD 0.48); BHI tight 1.21 (SD 0.38) P < .001). Conclusion. Impairment in cerebrovascular reactivity was found with inflated pseudo-tie. However, mean BHI is still within a range of considered normal. The situation may differ in patients with vascular risk factors, and confirmatory work is recommended. PMID:21076611

  9. Neckties and cerebrovascular reactivity in young healthy males: a pilot randomised crossover trial.

    PubMed

    Rafferty, Mark; Quinn, Terence J; Dawson, Jesse; Walters, Matthew

    2010-01-01

    Background. A necktie may elevate intracranial pressure through compression of venous return. We hypothesised that a tight necktie would deleteriously alter cerebrovascular reactivity. Materials and Methods. A necktie was simulated using bespoke apparatus comprising pneumatic inner-tube with aneroid pressure-gauge. Using a randomised crossover design, cerebrovascular reactivity was measured with the "pseudo-tie" worn inflated or deflated for 5 minutes (simulating tight/loose necktie resp.). Reactivity was calculated using breath hold index (BHI) and paired "t" testing used for comparative analysis. Results. We enrolled 40 healthy male volunteers. There was a reduction in cerebrovascular reactivity of 0.23 units with "tight" pseudotie (BHI loose 1.44 (SD 0.48); BHI tight 1.21 (SD 0.38) P < .001). Conclusion. Impairment in cerebrovascular reactivity was found with inflated pseudo-tie. However, mean BHI is still within a range of considered normal. The situation may differ in patients with vascular risk factors, and confirmatory work is recommended. PMID:21076611

  10. Crossover behavior of the thermal conductance and Kramers' transition rate theory.

    PubMed

    Velizhanin, Kirill A; Sahu, Subin; Chien, Chih-Chun; Dubi, Yonatan; Zwolak, Michael

    2015-01-01

    Kramers' theory frames chemical reaction rates in solution as reactants overcoming a barrier in the presence of friction and noise. For weak coupling to the solution, the reaction rate is limited by the rate at which the solution can restore equilibrium after a subset of reactants have surmounted the barrier to become products. For strong coupling, there are always sufficiently energetic reactants. However, the solution returns many of the intermediate states back to the reactants before the product fully forms. Here, we demonstrate that the thermal conductance displays an analogous physical response to the friction and noise that drive the heat current through a material or structure. A crossover behavior emerges where the thermal reservoirs dominate the conductance at the extremes and only in the intermediate region are the intrinsic properties of the lattice manifest. Not only does this shed new light on Kramers' classic turnover problem, this result is significant for the design of devices for thermal management and other applications, as well as the proper simulation of transport at the nanoscale.

  11. Coherent transport through spin-crossover magnet Fe2 complexes

    NASA Astrophysics Data System (ADS)

    Huang, Jing; Xie, Rong; Wang, Weiyi; Li, Qunxiang; Yang, Jinlong

    2015-12-01

    As one of the most promising building blocks in molecular spintronics, spin crossover (SCO) complexes have attracted increasing attention due to their magnetic bistability between the high-spin (HS) and low-spin (LS) states. Here, we explore the electronic structures and transport properties of SCO magnet Fe2 complexes with three different spin-pair configurations, namely [LS-LS], [LS-HS], and [HS-HS], by performing extensive density functional theory calculations combined with the non-equilibrium Green's function technique. Our calculations clearly reveal that the SCO magnet Fe2 complexes should display two-step spin transitions triggered by external stimuli, i.e. temperature or light, which confirm the previous phenomenological model and agree well with previous experimental measurements. Based on the calculated transport results, we observe a nearly perfect spin-filtering effect and negative differential resistance (NDR) behavior integrated in the SCO magnet Fe2 junction with the [HS-HS] configuration. The current through the [HS-HS] SCO magnet Fe2 complex under a small bias voltage is mainly contributed by the spin-down electrons, which is significantly larger than those of the [LS-LS] and [LS-HS] cases. The bias-dependent transmissions are responsible for the observed NDR effect. These theoretical findings suggest that SCO Fe2 complexes hold potential applications in molecular spintronic devices.As one of the most promising building blocks in molecular spintronics, spin crossover (SCO) complexes have attracted increasing attention due to their magnetic bistability between the high-spin (HS) and low-spin (LS) states. Here, we explore the electronic structures and transport properties of SCO magnet Fe2 complexes with three different spin-pair configurations, namely [LS-LS], [LS-HS], and [HS-HS], by performing extensive density functional theory calculations combined with the non-equilibrium Green's function technique. Our calculations clearly reveal that the SCO

  12. Algorithms for optimizing cross-overs in DNA shuffling

    PubMed Central

    2012-01-01

    Background DNA shuffling generates combinatorial libraries of chimeric genes by stochastically recombining parent genes. The resulting libraries are subjected to large-scale genetic selection or screening to identify those chimeras with favorable properties (e.g., enhanced stability or enzymatic activity). While DNA shuffling has been applied quite successfully, it is limited by its homology-dependent, stochastic nature. Consequently, it is used only with parents of sufficient overall sequence identity, and provides no control over the resulting chimeric library. Results This paper presents efficient methods to extend the scope of DNA shuffling to handle significantly more diverse parents and to generate more predictable, optimized libraries. Our CODNS (cross-over optimization for DNA shuffling) approach employs polynomial-time dynamic programming algorithms to select codons for the parental amino acids, allowing for zero or a fixed number of conservative substitutions. We first present efficient algorithms to optimize the local sequence identity or the nearest-neighbor approximation of the change in free energy upon annealing, objectives that were previously optimized by computationally-expensive integer programming methods. We then present efficient algorithms for more powerful objectives that seek to localize and enhance the frequency of recombination by producing "runs" of common nucleotides either overall or according to the sequence diversity of the resulting chimeras. We demonstrate the effectiveness of CODNS in choosing codons and allocating substitutions to promote recombination between parents targeted in earlier studies: two GAR transformylases (41% amino acid sequence identity), two very distantly related DNA polymerases, Pol X and β (15%), and beta-lactamases of varying identity (26-47%). Conclusions Our methods provide the protein engineer with a new approach to DNA shuffling that supports substantially more diverse parents, is more deterministic

  13. Randomized crossover comparison of adhesively coupled colostomy pouching systems.

    PubMed

    Berg, Kirsten; Seidler, Heidi

    2005-03-01

    Ostomy pouching systems affect well being and quality of life, making selection of the appropriate system a key element of ostomy care. Several innovative adhesively coupled, two-piece systems are on the market. They feature flexible low profiles, allowing pouch removal/replacement without changing the skin barrier or wafer. This facilitates inspection or pouch changes without disrupting peristomal skin. Because few controlled trials compare pouching system effectiveness, a prospective, randomized open-label, crossover study was conducted. Under the supervision of ostomy care nurses in six outpatient clinics in Germany, clinical performance of and patient preferences for two adhesively coupled, closed-end pouching systems were compared during normal use. One is a gelatin/pectin-based skin barrier sealed to the pouch with a company-specific adhesive coupling technology (System E); the other, a grooved base plate wafer adhesive pouch coupling system (System F). Seventeen attributes and seven end-of-study measures that included comfort, flexibility, wear time, ease of removal, and overall performance were assessed. Informed, consenting participants were randomly assigned to use one system for five skin barrier/wafer changes or up to 15 days and subsequently switched to the alternative system for a similar period. The 39 participants used a total of 1,645 pouches and 342 skin barriers. All were found safe as determined by incidence and nature of the reported peristomal skin problems, subject withdrawals, and adverse events for both systems. However, System E provided longer pouch wear times (P < 0.01). End-phase ratings favored System E on 10 of the 17 attributes (P < 0.04) and System Fon none. More participants preferred System E on all seven end-of-study measures, five significantly (comfort, flexibility, wear time, ease of removal, and overall performance; (P < 0.02). These participant-reported, ostomy-related outcomes underscore the importance of product evaluation

  14. Crossover localisation is regulated by the neddylation posttranslational regulatory pathway.

    PubMed

    Jahns, Marina Tagliaro; Vezon, Daniel; Chambon, Aurélie; Pereira, Lucie; Falque, Matthieu; Martin, Olivier C; Chelysheva, Liudmila; Grelon, Mathilde

    2014-08-01

    Crossovers (COs) are at the origin of genetic variability, occurring across successive generations, and they are also essential for the correct segregation of chromosomes during meiosis. Their number and position are precisely controlled, however the mechanisms underlying these controls are poorly understood. Neddylation/rubylation is a regulatory pathway of posttranslational protein modification that is required for numerous cellular processes in eukaryotes, but has not yet been linked to homologous recombination. In a screen for meiotic recombination-defective mutants, we identified several axr1 alleles, disrupting the gene encoding the E1 enzyme of the neddylation complex in Arabidopsis. Using genetic and cytological approaches we found that axr1 mutants are characterised by a shortage in bivalent formation correlated with strong synapsis defects. We determined that the bivalent shortage in axr1 is not due to a general decrease in CO formation but rather due to a mislocalisation of class I COs. In axr1, as in wild type, COs are still under the control of the ZMM group of proteins. However, in contrast to wild type, they tend to cluster together and no longer follow the obligatory CO rule. Lastly, we showed that this deregulation of CO localisation is likely to be mediated by the activity of a cullin 4 RING ligase, known to be involved in DNA damage sensing during somatic DNA repair and mouse spermatogenesis. In conclusion, we provide evidence that the neddylation/rubylation pathway of protein modification is a key regulator of meiotic recombination. We propose that rather than regulating the number of recombination events, this pathway regulates their localisation, through the activation of cullin 4 RING ligase complexes. Possible targets for these ligases are discussed. PMID:25116939

  15. Crossover Localisation Is Regulated by the Neddylation Posttranslational Regulatory Pathway

    PubMed Central

    Jahns, Marina Tagliaro; Vezon, Daniel; Chambon, Aurélie; Pereira, Lucie; Falque, Matthieu; Martin, Olivier C.; Chelysheva, Liudmila; Grelon, Mathilde

    2014-01-01

    Crossovers (COs) are at the origin of genetic variability, occurring across successive generations, and they are also essential for the correct segregation of chromosomes during meiosis. Their number and position are precisely controlled, however the mechanisms underlying these controls are poorly understood. Neddylation/rubylation is a regulatory pathway of posttranslational protein modification that is required for numerous cellular processes in eukaryotes, but has not yet been linked to homologous recombination. In a screen for meiotic recombination-defective mutants, we identified several axr1 alleles, disrupting the gene encoding the E1 enzyme of the neddylation complex in Arabidopsis. Using genetic and cytological approaches we found that axr1 mutants are characterised by a shortage in bivalent formation correlated with strong synapsis defects. We determined that the bivalent shortage in axr1 is not due to a general decrease in CO formation but rather due to a mislocalisation of class I COs. In axr1, as in wild type, COs are still under the control of the ZMM group of proteins. However, in contrast to wild type, they tend to cluster together and no longer follow the obligatory CO rule. Lastly, we showed that this deregulation of CO localisation is likely to be mediated by the activity of a cullin 4 RING ligase, known to be involved in DNA damage sensing during somatic DNA repair and mouse spermatogenesis. In conclusion, we provide evidence that the neddylation/rubylation pathway of protein modification is a key regulator of meiotic recombination. We propose that rather than regulating the number of recombination events, this pathway regulates their localisation, through the activation of cullin 4 RING ligase complexes. Possible targets for these ligases are discussed. PMID:25116939

  16. Crossover localisation is regulated by the neddylation posttranslational regulatory pathway.

    PubMed

    Jahns, Marina Tagliaro; Vezon, Daniel; Chambon, Aurélie; Pereira, Lucie; Falque, Matthieu; Martin, Olivier C; Chelysheva, Liudmila; Grelon, Mathilde

    2014-08-01

    Crossovers (COs) are at the origin of genetic variability, occurring across successive generations, and they are also essential for the correct segregation of chromosomes during meiosis. Their number and position are precisely controlled, however the mechanisms underlying these controls are poorly understood. Neddylation/rubylation is a regulatory pathway of posttranslational protein modification that is required for numerous cellular processes in eukaryotes, but has not yet been linked to homologous recombination. In a screen for meiotic recombination-defective mutants, we identified several axr1 alleles, disrupting the gene encoding the E1 enzyme of the neddylation complex in Arabidopsis. Using genetic and cytological approaches we found that axr1 mutants are characterised by a shortage in bivalent formation correlated with strong synapsis defects. We determined that the bivalent shortage in axr1 is not due to a general decrease in CO formation but rather due to a mislocalisation of class I COs. In axr1, as in wild type, COs are still under the control of the ZMM group of proteins. However, in contrast to wild type, they tend to cluster together and no longer follow the obligatory CO rule. Lastly, we showed that this deregulation of CO localisation is likely to be mediated by the activity of a cullin 4 RING ligase, known to be involved in DNA damage sensing during somatic DNA repair and mouse spermatogenesis. In conclusion, we provide evidence that the neddylation/rubylation pathway of protein modification is a key regulator of meiotic recombination. We propose that rather than regulating the number of recombination events, this pathway regulates their localisation, through the activation of cullin 4 RING ligase complexes. Possible targets for these ligases are discussed.

  17. Nutrition intervention for migraine: a randomized crossover trial

    PubMed Central

    2014-01-01

    Background Limited evidence suggests that dietary interventions may offer a promising approach for migraine. The purpose of this study was to determine the effects of a low-fat plant-based diet intervention on migraine severity and frequency. Methods Forty-two adult migraine sufferers were recruited from the general community in Washington, DC, and divided randomly into two groups. This 36-week crossover study included two treatments: dietary instruction and placebo supplement. Each treatment period was 16 weeks, with a 4-week washout between. During the diet period, a low-fat vegan diet was prescribed for 4 weeks, after which an elimination diet was used. Participants were assessed at the beginning, midpoint, and end of each period. Significance was determined using student’s t-tests. Results Worst headache pain in last 2 weeks, as measured by visual analog scale, was initially 6.4/10 cm (SD 2.1 cm), and declined 2.1 cm during the diet period and 0.7 cm during the supplement period (p=0.03). Average headache intensity (0–10 scale) was initially 4.2 (SD 1.4) per week, and this declined by 1.0 during the diet period and by 0.5 during the supplement period (p=0.20). Average headache frequency was initially 2.3 (SD 1.8) per week, and this declined by 0.3 during the diet period and by 0.4 during the supplement period (p=0.61). The Patient’s Global Impression of Change showed greater improvement in pain during the diet period (p<0.001). Conclusions These results suggest that a nutritional approach may be a useful part of migraine treatment, but that methodologic issues necessitate further research. Trial registration Clinicaltrials.gov, NCT01699009 and NCT01547494. PMID:25339342

  18. Randomized Polypill Crossover Trial in People Aged 50 and Over

    PubMed Central

    Wald, David S.; Morris, Joan K.; Wald, Nicholas J.

    2012-01-01

    Background A Polypill is proposed for the primary prevention of cardiovascular disease in people judged to be at risk on account of their age alone. Its efficacy in reducing cholesterol and blood pressure is uncertain. Methods We conducted a randomized double-blind placebo-controlled crossover trial of a Polypill among individuals aged 50+ without a history of cardiovascular disease and compared the reductions with those predicted from published estimates of the effects of the individual drugs. Participants took the Polypill (amlodipine 2.5 mg, losartan 25 mg, hydrochlorothiazide 12.5 mg and simvastatin 40 mg) each evening for 12 weeks and a placebo each evening for 12 weeks in random sequence. The mean within-person differences in blood pressure and low density lipoprotein (LDL) cholesterol at the end of each 12 week period were determined. Results 84 out of 86 participants completed both treatment periods. The mean systolic blood pressure was reduced by 17.9 mmHg (95% CI, 15.7–20.1) on the Polypill, diastolic blood pressure by 9.8 mmHg (8.1–11.5), and LDL cholesterol by 1.4 mmol/L (1.2–1.6), reductions of 12%, 11%, and 39% respectively. The results were almost identical to those predicted; 18.4 mmHg, 9.7 mmHg, and 1.4 mmol/L respectively. Conclusion The Polypill resulted in the predicted reductions in blood pressure and LDL cholesterol. Long term reductions of this magnitude would have a substantial effect in preventing heart attacks and strokes. Trial Registration Controlled-Trials.com ISRCTN36672232 PMID:22815989

  19. Synthesis and characterisation of new ditetrazole-ligands as more rigid building blocks of envisaged iron(II) spin-crossover coordination polymers

    NASA Astrophysics Data System (ADS)

    Muttenthaler, Markus; Bartel, Matthias; Weinberger, Peter; Hilscher, Gerfried; Linert, Wolfgang

    2005-05-01

    As the ligand system plays the most important role in the behaviour of the spin-transition of iron(II) spin-crossover compounds a series of eight new mainly bridging di-tetrazole ligands were synthesised and produced new insights into spacer modifications as well as geometric prerequisites of the ligand and their impact on spin-crossover behaviour. The focus laid on aryl-spaced tetrazole ligands, which were interesting analogues to the well-known alkyl-di-tetrazoles due to expected enhanced interaction within the molecular structure through π-π-stacking. The results of this fundamental study yielded further guidelines to optimize and fine-tune the ligand design, which are envisaged to be used for spin-crossover iron(II) coordination polymers of high T½-values with abrupt spin transition behaviour. Additionally, one new SCO compound [μ-Tris(1-[1,1-dimethyl-2-(1 H-tetrazol-1-yl)ethyl]-1 H-tetrazole- N4, N4')iron(II)] bis(tetrafluoroborate)—[Fe( dtmp) 3](BF 4) 2—is presented. The compound features a spin transition around 160 K with a small thermal hysteresis of 5 K.

  20. Multiple mechanisms limit meiotic crossovers: TOP3α and two BLM homologs antagonize crossovers in parallel to FANCM

    PubMed Central

    Séguéla-Arnaud, Mathilde; Crismani, Wayne; Larchevêque, Cécile; Mazel, Julien; Froger, Nicole; Choinard, Sandrine; Lemhemdi, Afef; Macaisne, Nicolas; Van Leene, Jelle; Gevaert, Kris; De Jaeger, Geert; Chelysheva, Liudmilla; Mercier, Raphael

    2015-01-01

    Meiotic crossovers (COs) have two important roles, shuffling genetic information and ensuring proper chromosome segregation. Despite their importance and a large excess of precursors (i.e., DNA double-strand breaks, DSBs), the number of COs is tightly regulated, typically one to three per chromosome pair. The mechanisms ensuring that most DSBs are repaired as non-COs and the evolutionary forces imposing this constraint are poorly understood. Here we identified Topoisomerase3α (TOP3α) and the RECQ4 helicases—the Arabidopsis slow growth suppressor 1 (Sgs1)/Bloom syndrome protein (BLM) homologs—as major barriers to meiotic CO formation. First, the characterization of a specific TOP3α mutant allele revealed that, in addition to its role in DNA repair, this topoisomerase antagonizes CO formation. Further, we found that RECQ4A and RECQ4B constitute the strongest meiotic anti-CO activity identified to date, their concomitant depletion leading to a sixfold increase in CO frequency. In both top3α and recq4ab mutants, DSB number is unaffected, and extra COs arise from a normally minor pathway. Finally, both TOP3α and RECQ4A/B act independently of the previously identified anti-CO Fanconi anemia of complementation group M (FANCM) helicase. This finding shows that several parallel pathways actively limit CO formation and suggests that the RECQA/B and FANCM helicases prevent COs by processing different substrates. Despite a ninefold increase in CO frequency, chromosome segregation was unaffected. This finding supports the idea that CO number is restricted not because of mechanical constraints but likely because of the long-term costs of recombination. Furthermore, this work demonstrates how manipulating a few genes holds great promise for increasing recombination frequency in plant-breeding programs. PMID:25825745

  1. Two-phase flow in porous media: Crossover from capillary fingering to compact invasion for drainage

    SciTech Connect

    Ferer, M.V.; Bromhal, G.S.; Smith, D.H.

    2005-02-01

    It had been predicted that the capillary fingering observed at small capillary numbers should change or cross over to compact invasion at larger capillary numbers or longer times [D. Wilkinson, Phys. Rev. A 34, 1380 (1986)]. We present results from pore-level modeling in two dimensions for the average position (related to the position of the interface) of the injected fluid as well as the width of the interface between the injected, nonwetting fluid and the defending, wetting fluid. These results are entirely consistent with the predicted crossover from the fractal flow characterized by invasion percolation with trapping (IPWT) to compact/linear/stable flow, where the position of the injected fluid advances linearly with time and where the width of the interface is constant. Furthermore, our results for the characteristic time, at which the crossover occurs, agree with the predictions of Wilkinson. To focus on the effect of capillary number, we are considering only viscosity-matched flows where both fluids have the same viscosities. To our knowledge, these are the first pore-level modeling results that quantitatively test the general predictions of Wilkinson for this capillary crossover in the case of drainage. Our modeling results are used to provide closed form expressions predicting the dependence of average position and interfacial width upon capillary number and time, regardless of the size of the system. The size scaling inherent in the crossover combined with our results locating the upper and lower bounds of the crossover regime enable us to predict the location of the crossover for two-dimensional systems of different size. These predictions are compared with flow patterns from experiments in the literature. The agreement between our predictions and the experimental flow patterns indicates that the experiments exhibit the same IPWT to compact crossover observed in our modeling.

  2. Two-phase flow in porous media: Crossover from capillary fingering to compact invasion for drainage.

    PubMed

    Ferer, M; Bromhal, Grant S; Smith, Duane H

    2005-02-01

    It had been predicted that the capillary fingering observed at small capillary numbers should change or cross over to compact invasion at larger capillary numbers or longer times [D. Wilkinson, Phys. Rev. A 34, 1380 (1986)]. We present results from pore-level modeling in two dimensions for the average position (related to the position of the interface) of the injected fluid as well as the width of the interface between the injected, nonwetting fluid and the defending, wetting fluid. These results are entirely consistent with the predicted crossover from the fractal flow characterized by invasion percolation with trapping (IPWT) to compact/linear/stable flow, where the position of the injected fluid advances linearly with time and where the width of the interface is constant. Furthermore, our results for the characteristic time, at which the crossover occurs, agree with the predictions of Wilkinson. To focus on the effect of capillary number, we are considering only viscosity-matched flows where both fluids have the same viscosities. To our knowledge, these are the first pore-level modeling results that quantitatively test the general predictions of Wilkinson for this capillary crossover in the case of drainage. Our modeling results are used to provide closed form expressions predicting the dependence of average position and interfacial width upon capillary number and time, regardless of the size of the system. The size scaling inherent in the crossover combined with our results locating the upper and lower bounds of the crossover regime enable us to predict the location of the crossover for two-dimensional systems of different size. These predictions are compared with flow patterns from experiments in the literature. The agreement between our predictions and the experimental flow patterns indicates that the experiments exhibit the same IPWT to compact crossover observed in our modeling. PMID:15783415

  3. Covariance and crossover matrix guided differential evolution for global numerical optimization.

    PubMed

    Li, YongLi; Feng, JinFu; Hu, JunHua

    2016-01-01

    Differential evolution (DE) is an efficient and robust evolutionary algorithm and has wide application in various science and engineering fields. DE is sensitive to the selection of mutation and crossover strategies and their associated control parameters. However, the structure and implementation of DEs are becoming more complex because of the diverse mutation and crossover strategies that use distinct parameter settings during the different stages of the evolution. A novel strategy is used in this study to improve the crossover and mutation operations. The crossover matrix, instead of a crossover operator and its control parameter CR, is proposed to implement the function of the crossover operation. Meanwhile, Gaussian distribution centers the best individuals found in each generation based on the proposed covariance matrix, which is generated between the best individual and several better individuals. Improved mutation operator based on the crossover matrix is randomly selected to generate the trial population. This operator is used to generate high-quality solutions to improve the capability of exploitation and enhance the preference of exploration. In addition, the memory population is randomly chosen from previous generation and used to control the search direction in the novel mutation strategy. Accordingly, the diversity of the population is improved. Thus, CCDE, which is a novel efficient and simple DE variant, is presented in this paper. CCDE has been tested on 30 benchmarks and 5 real-world optimization problems from the IEEE Congress on Evolutionary Computation (CEC) 2014 and CEC 2011, respectively. Experimental and statistical results demonstrate the effectiveness of CCDE for global numerical and engineering optimization. CCDE can solve the test benchmark functions and engineering problems more successfully than the other DE variants and algorithms from CEC 2014.

  4. Covariance and crossover matrix guided differential evolution for global numerical optimization.

    PubMed

    Li, YongLi; Feng, JinFu; Hu, JunHua

    2016-01-01

    Differential evolution (DE) is an efficient and robust evolutionary algorithm and has wide application in various science and engineering fields. DE is sensitive to the selection of mutation and crossover strategies and their associated control parameters. However, the structure and implementation of DEs are becoming more complex because of the diverse mutation and crossover strategies that use distinct parameter settings during the different stages of the evolution. A novel strategy is used in this study to improve the crossover and mutation operations. The crossover matrix, instead of a crossover operator and its control parameter CR, is proposed to implement the function of the crossover operation. Meanwhile, Gaussian distribution centers the best individuals found in each generation based on the proposed covariance matrix, which is generated between the best individual and several better individuals. Improved mutation operator based on the crossover matrix is randomly selected to generate the trial population. This operator is used to generate high-quality solutions to improve the capability of exploitation and enhance the preference of exploration. In addition, the memory population is randomly chosen from previous generation and used to control the search direction in the novel mutation strategy. Accordingly, the diversity of the population is improved. Thus, CCDE, which is a novel efficient and simple DE variant, is presented in this paper. CCDE has been tested on 30 benchmarks and 5 real-world optimization problems from the IEEE Congress on Evolutionary Computation (CEC) 2014 and CEC 2011, respectively. Experimental and statistical results demonstrate the effectiveness of CCDE for global numerical and engineering optimization. CCDE can solve the test benchmark functions and engineering problems more successfully than the other DE variants and algorithms from CEC 2014. PMID:27512635

  5. Visual Rehabilitation in Chronic Cerebral Blindness: A Randomized Controlled Crossover Study.

    PubMed

    Elshout, Joris A; van Asten, Freekje; Hoyng, Carel B; Bergsma, Douwe P; van den Berg, Albert V

    2016-01-01

    The treatment of patients suffering from cerebral blindness following stroke is a topic of much recent interest. Several types of treatment are under investigation, such as substitution with prisms and compensation training of saccades. A third approach, aimed at vision restitution is controversial, as a proper controlled study design is missing. In the current study, 27 chronic stroke patients with homonymous visual field defects were trained at home with a visual training device. We used a discrimination task for two types of stimuli: a static point stimulus and a new optic flow-discontinuity stimulus. Using a randomized controlled crossover design, each patient received two successive training rounds, one with high contrast stimuli in their affected hemifield (test) and one round with low-contrast stimuli in their intact hemifield (control). Goldmann and Humphrey perimetry were performed at the start of the study and following each training round. In addition, reading performance was measured. Goldmann perimetry revealed a statistically significant reduction of the visual field defect after the test training, but not after the control training or after no intervention. For both training rounds combined, Humphrey perimetry revealed that the effect of a directed training (sensitivity change in trained hemifield) exceeded that of an undirected training (sensitivity change in untrained hemifield). The interaction between trained and tested hemifield was just above the threshold of significance (p = 0.058). Interestingly, reduction of the field defect assessed by Goldmann perimetry increases with the difference between defect size as measured by Humphrey and Goldmann perimetry prior to training. Moreover, improvement of visual sensitivity measured by Humphrey perimetry increases with the fraction of non-responsive elements (i.e., more relative field loss) in Humphrey perimetry prior to training. Reading speed revealed a significant improvement after training. Our

  6. Visual Rehabilitation in Chronic Cerebral Blindness: A Randomized Controlled Crossover Study

    PubMed Central

    Elshout, Joris A.; van Asten, Freekje; Hoyng, Carel B.; Bergsma, Douwe P.; van den Berg, Albert V.

    2016-01-01

    The treatment of patients suffering from cerebral blindness following stroke is a topic of much recent interest. Several types of treatment are under investigation, such as substitution with prisms and compensation training of saccades. A third approach, aimed at vision restitution is controversial, as a proper controlled study design is missing. In the current study, 27 chronic stroke patients with homonymous visual field defects were trained at home with a visual training device. We used a discrimination task for two types of stimuli: a static point stimulus and a new optic flow-discontinuity stimulus. Using a randomized controlled crossover design, each patient received two successive training rounds, one with high contrast stimuli in their affected hemifield (test) and one round with low-contrast stimuli in their intact hemifield (control). Goldmann and Humphrey perimetry were performed at the start of the study and following each training round. In addition, reading performance was measured. Goldmann perimetry revealed a statistically significant reduction of the visual field defect after the test training, but not after the control training or after no intervention. For both training rounds combined, Humphrey perimetry revealed that the effect of a directed training (sensitivity change in trained hemifield) exceeded that of an undirected training (sensitivity change in untrained hemifield). The interaction between trained and tested hemifield was just above the threshold of significance (p = 0.058). Interestingly, reduction of the field defect assessed by Goldmann perimetry increases with the difference between defect size as measured by Humphrey and Goldmann perimetry prior to training. Moreover, improvement of visual sensitivity measured by Humphrey perimetry increases with the fraction of non-responsive elements (i.e., more relative field loss) in Humphrey perimetry prior to training. Reading speed revealed a significant improvement after training. Our

  7. 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

  8. Design

    ERIC Educational Resources Information Center

    Buchanan, Richard; Cross, Nigel; Durling, David; Nelson, Harold; Owen, Charles; Valtonen, Anna; Boling, Elizabeth; Gibbons, Andrew; Visscher-Voerman, Irene

    2013-01-01

    Scholars representing the field of design were asked to identify what they considered to be the most exciting and imaginative work currently being done in their field, as well as how that work might change our understanding. The scholars included Richard Buchanan, Nigel Cross, David Durling, Harold Nelson, Charles Owen, and Anna Valtonen. Scholars…

  9. Peer Assessment Enhances Student Learning: The Results of a Matched Randomized Crossover Experiment in a College Statistics Class

    PubMed Central

    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. PMID:26683053

  10. Analysis of dual-end-pumped Nd3+-doped index-crossover gain guided-index antiguided fiber laser

    NASA Astrophysics Data System (ADS)

    Shen, Xiao; Wei, Wei; Zou, Hui; Zhang, Liaolin

    2016-05-01

    A dual-end pumped Nd3+-doped index-crossover gain guided-index antiguided (IGG-IAG) fiber laser is analyzed in theory. Pump light propagation and output laser characteristics are both explored by solving the related rate equations. Simulation results show that pump power confined in the IGG-IAG fiber core is larger and more uniform than that of the gain-guided and index-antiguided(GG-IAG) fiber, and the optimum fiber length and the output power of the IGG-IAG fiber laser are both larger than that of GG-IAG fiber laser. The relationship between threshold pump power and doped concentration, fiber length, fiber radius is researched respectively. The analysis results give out a method for the optimal design of the IGG-IAG fiber laser.

  11. 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.

  12. Crossover from 3D to 2D quantum transport in Bi2Se3/In2Se3 superlattices.

    PubMed

    Zhao, Yanfei; Liu, Haiwen; Guo, Xin; Jiang, Ying; Sun, Yi; Wang, Huichao; Wang, Yong; Li, Han-Dong; Xie, Mao-Hai; Xie, Xin-Cheng; Wang, Jian

    2014-09-10

    The topological insulator/normal insulator (TI/NI) superlattices (SLs) with multiple Dirac channels are predicted to offer great opportunity to design novel materials and investigate new quantum phenomena. Here, we report first transport studies on the SLs composed of TI Bi2Se3 layers sandwiched by NI In2Se3 layers artificially grown by molecular beam epitaxy (MBE). The transport properties of two kinds of SL samples show convincing evidence that the transport dimensionality changes from three-dimensional (3D) to two-dimensional (2D) when decreasing the thickness of building block Bi2Se3 layers, corresponding to the crossover from coherent TI transport to separated TI channels. Our findings provide the possibility to realizing "3D surface states" in TI/NI SLs.

  13. 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

  14. Crossover interference in Saccharomyces cerevisiae requires a TID1/RDH54- and DMC1-dependent pathway.

    PubMed Central

    Shinohara, Miki; Sakai, Kazuko; Shinohara, Akira; Bishop, Douglas K

    2003-01-01

    Two RecA-like recombinases, Rad51 and Dmc1, function together during double-strand break (DSB)-mediated meiotic recombination to promote homologous strand invasion in the budding yeast Saccharomyces cerevisiae. Two partially redundant proteins, Rad54 and Tid1/Rdh54, act as recombinase accessory factors. Here, tetrad analysis shows that mutants lacking Tid1 form four-viable-spore tetrads with levels of interhomolog crossover (CO) and noncrossover recombination similar to, or slightly greater than, those in wild type. Importantly, tid1 mutants show a marked defect in crossover interference, a mechanism that distributes crossover events nonrandomly along chromosomes during meiosis. Previous work showed that dmc1Delta mutants are strongly defective in strand invasion and meiotic progression and that these defects can be partially suppressed by increasing the copy number of RAD54. Tetrad analysis is used to show that meiotic recombination in RAD54-suppressed dmc1Delta cells is similar to that in tid1; the frequency of COs and gene conversions is near normal, but crossover interference is defective. These results support the proposal that crossover interference acts at the strand invasion stage of recombination. PMID:12702674

  15. Spin crossover and hyperfine interactions of iron in (Mg ,Fe ) CO3 ferromagnesite

    NASA Astrophysics Data System (ADS)

    Hsu, Han; Huang, Sheng-Chieh

    2016-08-01

    Ferromagnesite, an iron-bearing carbonate stable up to 100-115 GPa, is believed to be the major carbon carrier in the earth's lower mantle and play a key role in the earth's deep carbon cycle. In this paper, we use the local density approximation plus self-consistent Hubbard U (LDA+Usc) method to study the iron spin crossover in ferromagnesite with a wide range of iron concentration (12.5-100%). Our calculation shows that this mineral undergoes a crossover from the high-spin (HS) (S =2 ) to the low-spin (LS) (S =0 ) state at around 45-50 GPa, regardless of the iron concentration. The intermediate-spin (S =1 ) state is energetically unfavorable and not involved in spin crossover. The anomalous changes of volume, density, and bulk modulus accompanying the spin crossover obtained in our calculation are in great agreement with experiments. Our calculation also predicts that an abrupt change of the iron nuclear quadrupole splitting, from ≳2.8 mm/s to ≲0.3 mm/s, can be observed in Mössbauer spectra at 45-50 GPa as a signature of the HS-LS crossover.

  16. Miscible viscous fingering in three dimensions: fractal-to-compact crossover and interfacial roughness.

    PubMed

    Ferer, M; Bromhal, Grant S; Smith, Duane H

    2009-07-01

    Using our standard pore-level model, we have extended our earlier study of the crossover from fractal viscous fingering to compact /linear flow at a characteristic crossover time, tau , in three dimensions to systems with as many as a 10(6) pore bodies. These larger systems enable us to investigate the flows in the fully compact/well-past-crossover regime. The center of mass of the injected fluid exhibits basically the same behavior as found earlier but with an improved characteristic time. However, our earlier study of much smaller systems was unable to study the interfacial width in the important well-past-crossover regime, ttau. Now, we can study both the time evolution and roughness of the interfacial width. The interfacial width exhibits the same fractal-to-compact crossover as the center of mass, with the same characteristic time. In the fully compact regime, ttau, the interfacial width grows approximately linearly with time so that the standard growth exponent is approximately unity, beta=1.0+/-0.1. We find that neither is the interface self-affine nor is the roughness of the interface in the compact regime consistent with an effective long-range surface tension as assumed by various theories. In fact, similar to Lévy flights, the height variations across the interface appear to be random with occasional large height variations. PMID:19658710

  17. Miscible viscous fingering in three dimensions: Fractal-to-compact crossover and interfacial roughness

    SciTech Connect

    Ferer, M.; Bromhal, Grant S.; Smith, Duane H.

    2009-07-01

    Using our standard pore-level model, we have extended our earlier study of the crossover from fractal viscous fingering to compact/linear flow at a characteristic crossover time, τ, in three dimensions to systems with as many as a 106 pore bodies. These larger systems enable us to investigate the flows in the fully compact/well-past-crossover regime. The center of mass of the injected fluid exhibits basically the same behavior as found earlier but with an improved characteristic time. However, our earlier study of much smaller systems was unable to study the interfacial width in the important well-past-crossover regime, t >> τ. Now, we can study both the time evolution and roughness of the interfacial width. The interfacial width exhibits the same fractal-to-compact crossover as the center of mass, with the same characteristic time. In the fully compact regime, t >> τ, the interfacial width grows approximately linearly with time so that the standard growth exponent is approximately unity, β=1.0±0.1. We find that neither is the interface self-affine nor is the roughness of the interface in the compact regime consistent with an effective long-range surface tension as assumed by various theories. In fact, similar to Levy flights, the height variations across the interface appear to be random with occasional large height variations.

  18. Two measures of bilingualism in the memories of immigrants and indigenous minorities: crossover memories and codeswitching.

    PubMed

    Altman, Carmit

    2015-04-01

    Two indices of bilingualism, crossover memories and codeswitching (CS), were explored in five groups of immigrant (English-Hebrew, Georgian-Hebrew Russian-Hebrew) and indigenous bilinguals (Arabic-Hebrew, Hebrew-English). Participants recalled memories in response to cue words and then were asked to report the language of retrieval and provide a more elaborate narrative. More memories were 'same language' memories, recalled in the language of the experimental session/cue word, but as many as 48 % of the memories were crossovers, i.e. memories reported in a language other than the language of the session/cue word. In an effort to examine the ecological validity of the self-reported language of the memories, the frequency of CS in the elaborated narratives was investigated. For the entire sample, more CS was found for self-reported crossover memories in L2 sessions. In a further analysis of CS in crossover memories, collapsed across L1 and L2 sessions, significant differences emerged between immigrants and indigenous bilinguals. Differences between immigrant and non-immigrant bilinguals are discussed in terms of the role of activation in crossover memories.

  19. Ioffe-Regel crossover for plane-wave vibrational excitations in vitreous silica

    NASA Astrophysics Data System (ADS)

    Taraskin, S. N.; Elliott, S. R.

    2000-05-01

    The first Ioffe-Regel crossover for vibrational plane waves (when wavelength and mean free path are comparable) has been investigated theoretically for models of vitreous silica (v-SiO2) constructed by molecular dynamics. The crossover is found to be from a state of weak scattering to one of strong scattering, not vibrational localization. Three methods have been used to investigate the crossover: an analysis of the time evolution of a vibrational plane wave, a spectral-density analysis in frequency space, and an analysis of the final scattered state in momentum space. The first Ioffe-Regel crossover frequency is found by all three methods to be ~1 THz for v-SiO2, for both longitudinal and transverse polarizations. A second Ioffe-Regel crossover occurs at ~6 THz for v-SiO2, corresponding to the frequency at which the mean free path is minimal (comparable to the interatomic spacing), and the spectral-density width is maximal (comparable to the frequency range of the vibrational density of states).

  20. Constructing higher order DNA origami arrays using DNA junctions of anti-parallel/parallel double crossovers

    NASA Astrophysics Data System (ADS)

    Ma, Zhipeng; Park, Seongsu; Yamashita, Naoki; Kawai, Kentaro; Hirai, Yoshikazu; Tsuchiya, Toshiyuki; Tabata, Osamu

    2016-06-01

    DNA origami provides a versatile method for the construction of nanostructures with defined shape, size and other properties; such nanostructures may enable a hierarchical assembly of large scale architecture for the placement of other nanomaterials with atomic precision. However, the effective use of these higher order structures as functional components depends on knowledge of their assembly behavior and mechanical properties. This paper demonstrates construction of higher order DNA origami arrays with controlled orientations based on the formation of two types of DNA junctions: anti-parallel and parallel double crossovers. A two-step assembly process, in which preformed rectangular DNA origami monomer structures themselves undergo further self-assembly to form numerically unlimited arrays, was investigated to reveal the influences of assembly parameters. AFM observations showed that when parallel double crossover DNA junctions are used, the assembly of DNA origami arrays occurs with fewer monomers than for structures formed using anti-parallel double crossovers, given the same assembly parameters, indicating that the configuration of parallel double crossovers is not energetically preferred. However, the direct measurement by AFM force-controlled mapping shows that both DNA junctions of anti-parallel and parallel double crossovers have homogeneous mechanical stability with any part of DNA origami.

  1. Flexible-to-semiflexible chain crossover on the pressure-area isotherm of a lipid bilayer

    NASA Astrophysics Data System (ADS)

    Krivonos, I. N.; Mukhin, S. I.

    2008-01-01

    We find theoretically that competition between ˜ K f q 4 and ˜ Qq 2 terms in the Fourier-transformed conformational energy of a single-lipid chain, in combination with interchain entropic repulsion in the hydrophobic part of the lipid (bi)layer, may cause a crossover on the bilayer pressure-area isotherm P( A)˜( A- A 0)-α. The crossover manifests itself in the transition from α = 5/3 to α = 3. Our microscopic model represents a single-lipid molecule as a worm-like chain with a finite irreducible cross-section area A 0, a flexural rigidity K f , and a stretching modulus Q in a parabolic potential with the self-consistent curvature B( A) formed by entropic interactions between hydrocarbon chains in the lipid layer. The crossover area A* obeys the relation Q/√ K f B( A*) ≈ 2. We predict a peculiar possibility of deducing the effective elastic moduli K f and Q of an individual hydrocarbon chain from the analysis of the isotherm with such a crossover. Also calculated is the crossover-related behavior of the area compressibility modulus K A , the equilibrium area per lipid A t , and the chain order parameter S(θ).

  2. Religious attendance and mortality: implications for the black-white mortality crossover.

    PubMed

    Dupre, Matthew E; Franzese, Alexis T; Parrado, Emilio A

    2006-02-01

    This study investigates the relationships among religious attendance, mortality, and the black-white mortality crossover. We build on prior research by examining the link between attendance and mortality while testing whether religious involvement captures an important source of population heterogeneity that contributes to a crossover Using data from the Established Populations for Epidemiologic Studies of the Elderly, we find a strong negative association between attendance and mortality. Our results also show evidence of a racial crossover in mortality rates for both men and women. When religious attendance is modeled in terms of differential frailty, clear gender differences emerge. For women, the effect of attendance is race- and age-dependent, modifying the age at crossover by 10 years. For men, however; the effect of attendance is not related to race and does not alter the crossover pattern. When other health risks are modeled in terms of differential frailty, wefind neither race nor age-related effects. Overall, the results highlight the importance of considering religious attendance when examining racial and gender differences in age-specific mortality rates.

  3. BCS-BEC crossover in atomic Fermi gases with a narrow resonance

    SciTech Connect

    Jensen, L. M.; Nilsen, H. M.; Watanabe, Gentaro

    2006-10-15

    We determine the effects on the BCS-BEC crossover of the energy dependence of the effective two-body interaction, which at low energies is determined by the effective range. To describe interactions with an effective range of either sign, we consider a single-channel model with a two-body interaction having an attractive square well and a repulsive square barrier. We investigate the two-body scattering properties of the model, and then solve the Eagles-Leggett equations for the zero temperature crossover, determining the momentum dependent gap and the chemical potential self-consistently. From this we investigate the dependence of the crossover on the effective range of the interaction.

  4. Universal low-temperature crossover in two-channel Kondo models

    NASA Astrophysics Data System (ADS)

    Mitchell, Andrew K.; Sela, Eran

    2012-06-01

    An exact expression is derived for the electron Green function in two-channel Kondo models with one and two impurities, describing the crossover from non-Fermi liquid (NFL) behavior at intermediate temperatures to standard Fermi liquid (FL) physics at low temperatures. Symmetry-breaking perturbations generically present in experiment ensure the standard low-energy FL description, but the full crossover is wholly characteristic of the unstable NFL state. Distinctive conductance lineshapes in quantum dot devices should result. We exploit a connection between this crossover and one occurring in a classical boundary Ising model to calculate real-space electron densities at finite temperature. The single universal finite-temperature Green function is then extracted by inverting the integral transformation relating these Friedel oscillations to the t matrix. Excellent agreement is demonstrated between exact results and full numerical renormalization group calculations.

  5. Electrostatic Spin Crossover in a Molecular Junction of a Single-Molecule Magnet Fe2

    NASA Astrophysics Data System (ADS)

    Hao, Hua; Zheng, Xiaohong; Song, Lingling; Wang, Ruining; Zeng, Zhi

    2012-01-01

    Spin crossover by means of an electric bias is investigated by spin-polarized density-functional theory calculations combined with the Keldysh nonequilibrium Green’s technique in a molecular junction, where an individual single-molecule magnet Fe2(acpybutO)(O2CMe)(NCS)2 is sandwiched between two infinite Au(100) nanoelectrodes. Our study demonstrates that the spin crossover, based on the Stark effect, is achieved in this molecular junction under an electric bias but not in the isolated molecule under external electric fields. The main reason is that the polarizability of the molecular junction has an opposite sign to that of the isolated molecule, and thus from the Stark effect the condition for the spin crossover in the molecular junction is contrary to that in the isolated molecule.

  6. Continuous and Discontinuous Dynamic Crossover in Supercooled Water in Computer Simulations.

    PubMed

    Ma, Zhonghua; Li, Jicun; Wang, Feng

    2015-08-20

    The dynamic crossover behavior of supercooled water as described by the first-principle based WAIL potential was investigated. Below the second liquid-liquid critical point, the viscosity shows a discontinuous jump consistent with a first-order phase transition between the high density liquid and the low density liquid. Above the critical point, a continuous transition occurs with only the first derivative of viscosity being discontinuous, and the dynamic crossover temperature is about 8 K below the thermodynamic switchover temperature. The 8 K shift can be explained by a delay in dynamic crossover, which does not occur until the more viscous liquid starts to dominate the population and jams the flow. On the basis of finite-size effects observed in our simulations, we believe that dynamic discontinuity may be observable above the critical point in confined water when the confinement is on a length scale shorter than the spatial correlation. PMID:27476514

  7. The commerce and crossover of resources: resource conservation in the service of resilience.

    PubMed

    Chen, Shoshi; Westman, Mina; Hobfoll, Stevan E

    2015-04-01

    Conservation of resources (COR) theory was originally introduced as a framework for understanding and predicting the consequences of major and traumatic stress, but following the work of Hobfoll and Shirom (1993), COR theory has been adopted to understanding and predicting work-related stress and both the stress and resilience that occur within work settings and work culture. COR theory underscores the critical role of resource possession, lack, loss and gain and depicts personal, social and material resources co-travelling in resource caravans, rather than piecemeal. We briefly review the principles of COR theory and integrate it in the crossover model, which provides a key mechanism for multi-person exchange of emotions, experiences and resources. Understanding the impact of resource reservoirs, resource passageways and crossover provides a framework for research and intervention promoting resilience to employees as well as to organizations. It emphasizes that the creation and maintenance of resource caravan passageways promote resource gain climates through resource crossover processes.

  8. The effects of a prophylactic knee brace and two neoprene knee sleeves on the performance of healthy athletes: a crossover randomized controlled trial.

    PubMed

    Mortaza, Niyousha; Ebrahimi, Ismail; Jamshidi, Ali Ashraf; Abdollah, Vahid; Kamali, Mohammad; Abas, Wan Abu Bakar Wan; Osman, Noor Azuan Abu

    2012-01-01

    Knee injury is one of the major problems in sports medicine, and the use of prophylactic knee braces is an attempt to reduce the occurrence and/or severity of injuries to the knee joint ligament(s) without inhibiting knee mobility. The aim of the present study was to examine the effect of one recently designed prophylactic knee brace and two neoprene knee sleeves upon performance of healthy athletes. Thirty-one healthy male athletes (age = 21.2 ± 1.5) volunteered as participants to examine the effect of prophylactic knee brace/sleeves on performance using isokinetic and functional tests. All subjects were tested in four conditions in a random order: 1. nonbraced (control) 2. using a neoprene knee sleeve 3. using a knee sleeve with four bilateral metal supports and 4. using a prophylactic knee brace. The study design was a crossover, randomized, controlled trial. Subjects completed single leg vertical jump, cross-over hop, and the isokinetic knee flexion and extension (at 60, 180, 300°/sec). Data were collected from the above tests and analyzed for jump height, cross-over hop distance, peak torque to body weight ratio and average power, respectively. Comparisons of these variables in the four testing conditions revealed no statistically significant difference (p>0.05). The selected prophylactic brace/sleeves did not significantly inhibit athletic performance which might verify that their structure and design have caused no complication in the normal function of the knee joint. Moreover, it could be speculated that, if the brace or the sleeves had any limiting effect, our young healthy athletic subjects were well able to generate a mean peak torque large enough to overcome this possible restriction. Further studies are suggested to investigate the long term effect of these prophylactic knee brace and sleeves as well as their possible effect on the adjacent joints to the knee.

  9. The Effects of a Prophylactic Knee Brace and Two Neoprene Knee Sleeves on the Performance of Healthy Athletes: A Crossover Randomized Controlled Trial

    PubMed Central

    Mortaza, Niyousha; Ebrahimi, Ismail; Jamshidi, Ali Ashraf; Abdollah, Vahid; Kamali, Mohammad; Abas, Wan Abu Bakar Wan; Osman, Noor Azuan Abu

    2012-01-01

    Knee injury is one of the major problems in sports medicine, and the use of prophylactic knee braces is an attempt to reduce the occurrence and/or severity of injuries to the knee joint ligament(s) without inhibiting knee mobility. The aim of the present study was to examine the effect of one recently designed prophylactic knee brace and two neoprene knee sleeves upon performance of healthy athletes. Thirty-one healthy male athletes (age = 21.2±1.5) volunteered as participants to examine the effect of prophylactic knee brace/sleeves on performance using isokinetic and functional tests. All subjects were tested in four conditions in a random order: 1. nonbraced (control) 2. using a neoprene knee sleeve 3. using a knee sleeve with four bilateral metal supports and 4. using a prophylactic knee brace. The study design was a crossover, randomized, controlled trial. Subjects completed single leg vertical jump, cross-over hop, and the isokinetic knee flexion and extension (at 60, 180, 300°/sec). Data were collected from the above tests and analyzed for jump height, cross-over hop distance, peak torque to body weight ratio and average power, respectively. Comparisons of these variables in the four testing conditions revealed no statistically significant difference (p>0.05). The selected prophylactic brace/sleeves did not significantly inhibit athletic performance which might verify that their structure and design have caused no complication in the normal function of the knee joint. Moreover, it could be speculated that, if the brace or the sleeves had any limiting effect, our young healthy athletic subjects were well able to generate a mean peak torque large enough to overcome this possible restriction. Further studies are suggested to investigate the long term effect of these prophylactic knee brace and sleeves as well as their possible effect on the adjacent joints to the knee. PMID:23185549

  10. Temperature effect on the small-to-large crossover lengthscale of hydrophobic hydration

    SciTech Connect

    Djikaev, Y. S. Ruckenstein, E.

    2013-11-14

    The thermodynamics of hydration is expected to change gradually from entropic for small solutes to enthalpic for large ones. The small-to-large crossover lengthscale of hydrophobic hydration depends on the thermodynamic conditions of the solvent such as temperature, pressure, presence of additives, etc. We attempt to shed some light on the temperature dependence of the crossover lengthscale by using a probabilistic approach to water hydrogen bonding that allows one to obtain an analytic expression for the number of bonds per water molecule as a function of both its distance to a solute and solute radius. Incorporating that approach into the density functional theory, one can examine the solute size effects on its hydration over the entire small-to-large lengthscale range at a series of different temperatures. Knowing the dependence of the hydration free energy on the temperature and solute size, one can also obtain its enthalpic and entropic contributions as functions of both temperature and solute size. These functions can provide some interesting insight into the temperature dependence of the crossover lengthscale of hydrophobic hydration. The model was applied to the hydration of spherical particles of various radii in water in the temperature range from T = 293.15 K to T = 333.15 K. The model predictions for the temperature dependence of the hydration free energy of small hydrophobes are consistent with the experimental and simulational data on the hydration of simple molecular solutes. Three alternative definitions for the small-to-large crossover length-scale of hydrophobic hydration are proposed, and their temperature dependence is obtained. Depending on the definition and temperature, the small-to-large crossover in the hydration mechanism is predicted to occur for hydrophobes of radii from one to several nanometers. Independent of its definition, the crossover length-scale is predicted to decrease with increasing temperature.

  11. Temperature effect on the small-to-large crossover lengthscale of hydrophobic hydration.

    PubMed

    Djikaev, Y S; Ruckenstein, E

    2013-11-14

    The thermodynamics of hydration is expected to change gradually from entropic for small solutes to enthalpic for large ones. The small-to-large crossover lengthscale of hydrophobic hydration depends on the thermodynamic conditions of the solvent such as temperature, pressure, presence of additives, etc. We attempt to shed some light on the temperature dependence of the crossover lengthscale by using a probabilistic approach to water hydrogen bonding that allows one to obtain an analytic expression for the number of bonds per water molecule as a function of both its distance to a solute and solute radius. Incorporating that approach into the density functional theory, one can examine the solute size effects on its hydration over the entire small-to-large lengthscale range at a series of different temperatures. Knowing the dependence of the hydration free energy on the temperature and solute size, one can also obtain its enthalpic and entropic contributions as functions of both temperature and solute size. These functions can provide some interesting insight into the temperature dependence of the crossover lengthscale of hydrophobic hydration. The model was applied to the hydration of spherical particles of various radii in water in the temperature range from T = 293.15 K to T = 333.15 K. The model predictions for the temperature dependence of the hydration free energy of small hydrophobes are consistent with the experimental and simulational data on the hydration of simple molecular solutes. Three alternative definitions for the small-to-large crossover length-scale of hydrophobic hydration are proposed, and their temperature dependence is obtained. Depending on the definition and temperature, the small-to-large crossover in the hydration mechanism is predicted to occur for hydrophobes of radii from one to several nanometers. Independent of its definition, the crossover length-scale is predicted to decrease with increasing temperature.

  12. Indicators of throwing arm fatigue in elite adolescent male baseball players: a randomized crossover trial.

    PubMed

    Freeston, Jonathan; Adams, Roger; Ferdinands, René E D; Rooney, Kieron

    2014-08-01

    Throwing carries an inherent risk of injury that worsens in the presence of arm fatigue. The purpose of this study was to identify markers that could facilitate the early detection of this type of fatigue, by comparing the response to bouts of throwing-specific and running-based exercise. Thirteen elite junior male baseball players were tested twice, 7 days apart with a randomized crossover design. They were assessed for shoulder proprioception, maximal throwing velocity, and throwing accuracy before and after a 10-minute bout of either throwing-specific (THROW) or general (RUN) exercise. Maximal throwing velocity was reduced similarly after both THROW and RUN bouts (-1.0 ± 0.4 vs. -0.6 ± 0.2 m·s-1, respectively; p ≤ 0.05); however, accuracy was only reduced after THROW (7.6 ± 3.4 cm; p ≤ 0.05). Arm soreness increased significantly more after THROW than RUN (3.5 ± 0.7 vs. 1.4 ± 0.5 km·h-1, respectively; p ≤ 0.05). Shoulder proprioception did not change after either exercise bout. The results suggest that throwing velocity is an indicator of general fatigue, whereas throwing accuracy and arm soreness are markers of arm fatigue. Shoulder proprioception does not seem to be a sensitive marker of either type of fatigue. Throwing velocity should be monitored to gauge overall fatigue levels, whereas accuracy and arm soreness should be closely monitored to gauge arm fatigue and throwing-induced injury risk. PMID:24513620

  13. Indicators of throwing arm fatigue in elite adolescent male baseball players: a randomized crossover trial.

    PubMed

    Freeston, Jonathan; Adams, Roger; Ferdinands, René E D; Rooney, Kieron

    2014-08-01

    Throwing carries an inherent risk of injury that worsens in the presence of arm fatigue. The purpose of this study was to identify markers that could facilitate the early detection of this type of fatigue, by comparing the response to bouts of throwing-specific and running-based exercise. Thirteen elite junior male baseball players were tested twice, 7 days apart with a randomized crossover design. They were assessed for shoulder proprioception, maximal throwing velocity, and throwing accuracy before and after a 10-minute bout of either throwing-specific (THROW) or general (RUN) exercise. Maximal throwing velocity was reduced similarly after both THROW and RUN bouts (-1.0 ± 0.4 vs. -0.6 ± 0.2 m·s-1, respectively; p ≤ 0.05); however, accuracy was only reduced after THROW (7.6 ± 3.4 cm; p ≤ 0.05). Arm soreness increased significantly more after THROW than RUN (3.5 ± 0.7 vs. 1.4 ± 0.5 km·h-1, respectively; p ≤ 0.05). Shoulder proprioception did not change after either exercise bout. The results suggest that throwing velocity is an indicator of general fatigue, whereas throwing accuracy and arm soreness are markers of arm fatigue. Shoulder proprioception does not seem to be a sensitive marker of either type of fatigue. Throwing velocity should be monitored to gauge overall fatigue levels, whereas accuracy and arm soreness should be closely monitored to gauge arm fatigue and throwing-induced injury risk.

  14. Ozone air pollution and ischaemic stroke occurrence: a case-crossover study in Nice, France

    PubMed Central

    Suissa, Laurent; Fortier, Mikael; Lachaud, Sylvain; Staccini, Pascal; Mahagne, Marie-Hélène

    2013-01-01

    Objectives Relationship between low-level air pollution and stroke is conflicting. This study was conducted to document the relationship between outdoor air pollution and ischaemic stroke occurrence. Design Time-stratified case-crossover analysis. Setting University Hospital of Nice, France. Participants All consecutive patients with ischaemic stroke living in Nice admitted in the University Hospital of Nice (France) between January 2007 and December 2011. Main outcome measure Association (adjusted OR) between daily levels of outdoor pollutants (ozone (O3), nitrogen dioxide (NO2), particulate matter (PM10) and sulfur dioxide (SO2)) and ischaemic stroke occurrence. Results 1729 patients with ischaemic stroke (mean age: 76.1±14.0 years; men: 46.7%) were enrolled. No significant association was found between stroke occurrence and short-term effects of all pollutants tested. In stratified analysis, we observed significant associations only between recurrent (n=280) and large artery ischaemic stroke (n=578) onset and short-term effect of O3 exposure. For an increase of 10 µg/m3 of O3 level, recurrent stroke risk (mean D-1, D-2 and D-3 lag) was increased by 12.1% (95% CI 1.5% to 23.9%) and large artery stroke risk (mean D-3 and D-4 lag) was increased by 8% (95% CI 2.0% to 16.6%). Linear dose–response relationship for both subgroups was found. Conclusions Our results confirm the relationship between low-level O3 exposure and ischaemic stroke in high vascular risk subgroup with linear exposure–response relation, independently of other pollutants and meteorological parameters. The physiopathological processes underlying this association between ischaemic stroke and O3 exposure remain to be investigated. PMID:24319276

  15. A top-crossover-to-bottom addressed segmented annular array using piezoelectric micromachined ultrasonic transducers

    NASA Astrophysics Data System (ADS)

    Jung, Joontaek; Lee, Wonjun; Kang, Woojin; Hong, Hyeryung; Yuen Song, Hi; Oh, Inn-yeal; Park, Chul Soon; Choi, Hongsoo

    2015-11-01

    We design and fabricate segmented annular arrays (SAAs) using piezoelectric micromachined ultrasonic transducers (pMUTs) to demonstrate the feasibility of acoustic focusing of ultrasound. The fabricated SAAs have 25 concentric top-electrode signal lines and eight bottom-electrodes for grounding to enable electronic steering of selectively grouped ultrasonic transducers from 2393 pMUT elements. Each element in the array is connected by top-crossover-to-bottom metal bridges, which reduce the parasitic capacitance. Circular-shaped pMUT elements, 120 μm in diameter, are fabricated using 1 μm-thick sol-gel lead zirconate titanate on a silicon wafer. To utilize the high-density pMUT array, a deep reactive ion etching process is used for anisotropic silicon etching to realize the transducer membranes. The resonant frequency and effective coupling coefficient of the elements, measured with an impedance analyzer, yields 1.517 MHz and 1.29%, respectively, in air. The SAAs using pMUTs are packaged on a printed circuit board and coated with parylene C for acoustic intensity measurements in water. The ultrasound generated by each segmented array is focused on a selected point in space. When a 5 Vpp, 1.5 MHz square wave is applied, the maximum spatial peak temporal average intensity ({{I}\\text{spta}} ) is found to be 79 mW cm-2 5 mm from the SAAs’ surface without beamforming. The beam widths (-3 dB) of ultrasonic radiation patterns in the elevation and azimuth directions are recorded as 3 and 3.4 mm, respectively. The results successfully show the feasibility of focusing ultrasound on a small area with SAAs using pMUTs.

  16. A randomised cross-over pharmacokinetic bioavailability study of synthetic versus kiwifruit-derived vitamin C.

    PubMed

    Carr, Anitra C; Bozonet, Stephanie M; Vissers, Margreet C M

    2013-11-11

    Kiwifruit are a rich source of vitamin C and also contain numerous phytochemicals, such as flavonoids, which may influence the bioavailability of kiwifruit-derived vitamin C. The aim of this study was to compare the relative bioavailability of synthetic versus kiwifruit-derived vitamin C using a randomised cross-over pharmacokinetic study design. Nine non-smoking males (aged 18-35 years) received either a chewable tablet (200 mg vitamin C) or the equivalent dose from gold kiwifruit (Actinidia chinensis var. Sungold). Fasting blood and urine were collected half hourly to hourly over the eight hours following intervention. The ascorbate content of the plasma and urine was determined using HPLC with electrochemical detection. Plasma ascorbate levels increased from 0.5 h after the intervention (P = 0.008). No significant differences in the plasma time-concentration curves were observed between the two interventions (P = 0.645). An estimate of the total increase in plasma ascorbate indicated complete uptake of the ingested vitamin C tablet and kiwifruit-derived vitamin C. There was an increase in urinary ascorbate excretion, relative to urinary creatinine, from two hours post intervention (P < 0.001). There was also a significant difference between the two interventions, with enhanced ascorbate excretion observed in the kiwifruit group (P = 0.016). Urinary excretion was calculated as ~40% and ~50% of the ingested dose from the vitamin C tablet and kiwifruit arms, respectively. Overall, our pharmacokinetic study has shown comparable relative bioavailability of kiwifruit-derived vitamin C and synthetic vitamin C.

  17. Josephson relation for the superfluid density in the BCS-BEC crossover

    SciTech Connect

    Taylor, Edward

    2008-04-01

    The Josephson relation for the superfluid density is derived for a Fermi superfluid in the BCS-BEC crossover. This identity extends the original Josephson relation for Bose superfluids. It gives a simple exact relation between the superfluid density {rho}{sub s} and the broken-symmetry Cooper pair order parameter {delta}{sub 0} in terms of the infrared limit of the pair fluctuation propagator. The same expression holds through the entire BCS-BEC crossover, describing the superfluid density of a weak-coupling BCS superfluid as well as the superfluid density of a Bose condensate of dimer molecules.

  18. Momentum Distribution and Condensate Fraction of a Fermion Gas in the BCS-BEC Crossover

    SciTech Connect

    Astrakharchik, G.E.; Boronat, J.; Casulleras, J.; Giorgini, S.

    2005-12-02

    By using the diffusion Monte Carlo method we calculate the one- and two-body density matrix of an interacting Fermi gas at T=0 in the BCS to Bose-Einstein condensate (BEC) crossover. Results for the momentum distribution of the atoms, as obtained from the Fourier transform of the one-body density matrix, are reported as a function of the interaction strength. Off-diagonal long-range order in the system is investigated through the asymptotic behavior of the two-body density matrix. The condensate fraction of pairs is calculated in the unitary limit and on both sides of the BCS-BEC crossover.

  19. Crossover of two power laws in the anomalous diffusion of a two lipid membrane

    SciTech Connect

    Bakalis, Evangelos E-mail: francesco.zerbetto@unibo.it; Höfinger, Siegfried; Zerbetto, Francesco E-mail: francesco.zerbetto@unibo.it; Venturini, Alessandro

    2015-06-07

    Molecular dynamics simulations of a bi-layer membrane made by the same number of 1-palmitoyl-2-oleoyl-glycero-3-phospho-ethanolamine and palmitoyl-oleoyl phosphatidylserine lipids reveal sub-diffusional motion, which presents a crossover between two different power laws. Fractional Brownian motion is the stochastic mechanism that governs the motion in both regimes. The location of the crossover point is justified with simple geometrical arguments and is due to the activation of the mechanism of circumrotation of lipids about each other.

  20. Finite-temperature collective dynamics of a Fermi gas in the BEC-BCS crossover.

    PubMed

    Wright, M J; Riedl, S; Altmeyer, A; Kohstall, C; Guajardo, E R Sánchez; Denschlag, J Hecker; Grimm, R

    2007-10-12

    We report on experimental studies on the collective behavior of a strongly interacting Fermi gas with tunable interactions and variable temperature. A scissors mode excitation in an elliptical trap is used to characterize the dynamics of the quantum gas in terms of hydrodynamic or near-collisionless behavior. We obtain a crossover phase diagram for collisional properties, showing a large region where a nonsuperfluid strongly interacting gas shows hydrodynamic behavior. In a narrow interaction regime on the BCS side of the crossover, we find a novel temperature-dependent damping peak, suggesting a relation to the superfluid phase transition. PMID:17995145

  1. Thermodynamics versus Local Density Fluctuations in the Metal-Mott-Insulator Crossover

    NASA Astrophysics Data System (ADS)

    Drewes, J. H.; Cocchi, E.; Miller, L. A.; Chan, C. F.; Pertot, D.; Brennecke, F.; Köhl, M.

    2016-09-01

    The crossover between a metal and a Mott insulator leads to a localization of fermions from delocalized Bloch states to localized states. We experimentally study this crossover using fermionic atoms in an optical lattice by measuring thermodynamic and local (on-site) density correlations. In the metallic phase at incommensurable filling we observe the violation of the local fluctuation-dissipation theorem indicating that the thermodynamics of the system cannot be characterized by local observables alone. In contrast, in the Mott insulator we observe the convergence of local and thermodynamic fluctuations indicating the absence of long-range density-density correlations.

  2. Crossover between weak antilocalization and weak localization in a magnetically doped topological insulator.

    PubMed

    Liu, Minhao; Zhang, Jinsong; Chang, Cui-Zu; Zhang, Zuocheng; Feng, Xiao; Li, Kang; He, Ke; Wang, Li-li; Chen, Xi; Dai, Xi; Fang, Zhong; Xue, Qi-Kun; Ma, Xucun; Wang, Yayu

    2012-01-20

    We report transport studies on magnetically doped Bi(2)Se(3) topological insulator ultrathin films grown by molecular beam epitaxy. The magnetotransport behavior exhibits a systematic crossover between weak antilocalization and weak localization with the change of magnetic impurity concentration, temperature, and magnetic field. We show that the localization property is closely related to the magnetization of the sample, and the complex crossover is due to the transformation of Bi(2)Se(3) from a topological insulator to a topologically trivial dilute magnetic semiconductor driven by magnetic impurities. This work demonstrates an effective way to manipulate the quantum transport properties of the topological insulators by breaking time-reversal symmetry.

  3. Recent Studies on Methanol Crossover in Liquid-Feed Direct Methanol Fuel Cells

    NASA Technical Reports Server (NTRS)

    Valdez, T. I.; Narayanan, S. R.

    2000-01-01

    In this work, the effects of methanol crossover and airflow rates on the cathode potential of an operating direct methanol fuel cell are explored. Techniques for quantifying methanol crossover in a fuel cell and for separating the electrical performance of each electrode in a fuel cell are discussed. The effect of methanol concentration on cathode potential has been determined to be significant. The cathode is found to be mass transfer limited when operating on low flow rate air and high concentrations of methanol. Improvements in cathode structure and operation at low methanol concentration have been shown to result in improved cell performance.

  4. Effect of radial-to-femoral access crossover on adverse outcomes in primary percutaneous coronary intervention.

    PubMed

    Azzalini, Lorenzo; Khan, Razi; Al-Hawwas, Malek; Hatem, Raja; Fortier, Annik; L'Allier, Philippe L; Ly, Hung Q

    2014-10-15

    We aimed to describe the impact of the vascular access used when patients are treated with primary percutaneous coronary intervention (PPCI) and to assess whether this translates into differences in angiographic outcomes. Patients with ST-elevation myocardial infarction who underwent PPCI were divided into 3 groups: successful radial access (RA), successful femoral access (FA), and Crossover (failed RA with need for bailout FA) groups. Vascular access-related time (VART) was defined as the delay in PPCI that can be attributed to vascular access-related issues. Study end point was the final corrected Thrombolysis In Myocardial Infarction frame count. Multivariable analysis was used to identify predictors of RA failure (RAF: FA + Crossover). We included 241 patients (RA, n = 172; FA, n = 49; Crossover, n = 20). Mean VART was longer in Crossover (10.3 [8.8 to 12.4] minutes), relative to RA (4.1 [3.2 to 5.5] minutes) and FA (4.6 [3.4 to 8.4] minutes, p <0.001). A similar situation was found for time-to-first device (Crossover 22.5 [20.3 to 32.0], RA 15.0 [12.0 to 19.8]; FA 17.9 [13.5 to 22.3] minutes, p <0.001) and total procedure time (Crossover 60.3 [51.6 to 71.5], RA 46.8 [38.1 to 59.7], FA 52.3 [41.9 to 74.7] minutes, p <0.001). No differences in corrected Thrombolysis In Myocardial Infarction frame count were observed (Crossover 26 [18 to 32] frames, RA 24 [18 to 32] frames, FA 25 [16 to 34] frames, p = 0.625). Killip class IV (odds ratio [OR] 3.628, 95% confidence interval [CI] 1.098 to 11.981, p = 0.035), cardiopulmonary resuscitation before arrival (OR 3.572, 95% CI 1.028 to 12.407, p = 0.045), and glomerular filtration rate (OR 0.861, 95% CI 0.758 to 0.978, p = 0.021) were independent predictors of RA failure. In conclusion, in the setting of PPCI, radial-to-FA crossover can lead to VART delays that do not affect angiographic outcomes, in comparison with successful RA.

  5. Bistable Magnetism and Potential for Voltage-Induced Spin Crossover in Dilute Magnetic Ferroelectrics

    NASA Astrophysics Data System (ADS)

    Weston, L.; Cui, X. Y.; Ringer, S. P.; Stampfl, C.

    2015-06-01

    A first-principles investigation into the magnetic ferroelectric PbTi1 -xCoxO3 has revealed a bi-stable magnetic system with strong spin-lattice coupling. The local distortions induced by the low-spin to high-spin crossover are ferroelectric in nature, and are characterized by the displacement of the dopant ion with respect to the surrounding O6 octahedral cage. We demonstrate how this spin-lattice effect could mediate magnetoelectric coupling and possible electric field induced spin-crossover, indicating a promising route to voltage manipulation of isolated spins in a solid-state system.

  6. Examining the Crossover from the Hadronic to Partonic Phase in QCD

    SciTech Connect

    Xu Mingmei; Yu Meiling; Liu Lianshou

    2008-03-07

    A mechanism, consistent with color confinement, for the transition between perturbative and physical vacua during the gradual crossover from the hadronic to partonic phase is proposed. The essence of this mechanism is the appearance and growing up of a kind of grape-shape perturbative vacuum inside the physical one. A percolation model based on simple dynamics for parton delocalization is constructed to exhibit this mechanism. The crossover from hadronic matter to sQGP (strongly coupled quark-gluon plasma) as well as the transition from sQGP to weakly coupled quark-gluon plasma with increasing temperature is successfully described by using this model.

  7. Fine-Scale Heterogeneity in Crossover Rate in the garnet-scalloped Region of the Drosophila melanogaster X Chromosome

    PubMed Central

    Singh, Nadia D.; Stone, Eric A.; Aquadro, Charles F.; Clark, Andrew G.

    2013-01-01

    Homologous recombination affects myriad aspects of genome evolution, from standing levels of nucleotide diversity to the efficacy of natural selection. Rates of crossing over show marked variability at all scales surveyed, including species-, population-, and individual-level differences. Even within genomes, crossovers are nonrandomly distributed in a wide diversity of taxa. Although intra- and intergenomic heterogeneities in crossover distribution have been documented in Drosophila, the scale and degree of crossover rate heterogeneity remain unclear. In addition, the genetic features mediating this heterogeneity are unknown. Here we quantify fine-scale heterogeneity in crossover distribution in a 2.1-Mb region of the Drosophila melanogaster X chromosome by localizing crossover breakpoints in 2500 individuals, each containing a single crossover in this specific X chromosome region. We show 90-fold variation in rates of crossing over at a 5-kb scale, place this variation in the context of several aspects of genome evolution, and identify several genetic features associated with crossover rates. Our results shed new light on the scale and magnitude of crossover rate heterogeneity in D. melanogaster and highlight potential features mediating this heterogeneity. PMID:23410829

  8. Atomoxetine for Hyperactivity in Autism Spectrum Disorders: Placebo-Controlled Crossover Pilot Trial

    ERIC Educational Resources Information Center

    Arnold, L. Eugene; Aman, Michael G.; Cook, Amelia M.; Witwer, Andrea N.; Hall, Kristy L.; Thompson, Susan; Ramadan, Yaser

    2006-01-01

    Objective: To explore placebo-controlled efficacy and safety of atomoxetine (ATX) for attention-deficit/hyperactivity disorder (ADHD) symptoms in children with autism spectrum disorders (ASD). Method: Children ages 5 to 15 with ASD and prominent ADHD symptoms were randomly assigned to order in a crossover of clinically titrated ATX and placebo, 6…

  9. Elastic anomalies in a spin-crossover system: ferropericlase at lower mantle conditions.

    PubMed

    Wu, Zhongqing; Justo, João F; Wentzcovitch, Renata M

    2013-05-31

    The discovery of a pressure induced iron-related spin crossover in Mg((1-x))Fe(x)O ferropericlase (Fp) and Mg-silicate perovskite, the major phases of Earth's lower mantle, has raised new questions about mantle properties which are of central importance to seismology. Despite extensive experimental work on the anomalous elasticity of Fp throughout the crossover, inconsistencies reported in the literature are still unexplained. Here we introduce a formulation for thermoelasticity of spin crossover systems, apply it to Fp by combining it with predictive first principles density-functional theory with on-site repulsion parameter U calculations, and contrast results with available data on samples with various iron concentrations. We explain why the shear modulus of Fp should not soften along the crossover, as observed in some experiments, predict its velocities at lower mantle conditions, and show the importance of constraining the elastic properties of minerals without extrapolations for analyses of the thermochemical state of this region. PMID:23767753

  10. The Crossover Generation: Baby Boomers and the Role of the Public Library

    ERIC Educational Resources Information Center

    Williamson, Kirsty; Bannister, Marion; Sullivan, Jen

    2010-01-01

    The article explores the concept of baby boomers as a "crossover" generation, one that embodies characteristics of previous and later generations. The context is the retirement of the baby boomers and its potential impact on the public library. Ethnographic method within a constructivist framework was used, employing the techniques of focus groups…

  11. Crossover Literature and Abjection: Geraldine McCaughrean's "The White Darkness"

    ERIC Educational Resources Information Center

    Falconer, Rachel

    2007-01-01

    This article provides a close reading of Geraldine McCaughrean's award-winning novel, "The White Darkness". It argues that this is a key text in the increasing debate about "crossover" literature. Whereas, traditionally, adolescent books were seen to offer compensatory fantasies to the adolescent reader, McCaughrean's text goes beyond this,…

  12. Drosophila FANCM Helicase Prevents Spontaneous Mitotic Crossovers Generated by the MUS81 and SLX1 Nucleases

    PubMed Central

    Kuo, H. Kenny; McMahan, Susan; Rota, Christopher M.; Kohl, Kathryn P.; Sekelsky, Jeff

    2014-01-01

    Several helicases function during repair of double-strand breaks and handling of blocked or stalled replication forks to promote pathways that prevent formation of crossovers. Among these are the Bloom syndrome helicase BLM and the Fanconi anemia group M (FANCM) helicase. To better understand functions of these helicases, we compared phenotypes of Drosophila melanogaster Blm and Fancm mutants. As previously reported for BLM, FANCM has roles in responding to several types of DNA damage in preventing mitotic and meiotic crossovers and in promoting the synthesis-dependent strand annealing pathway for repair of a double-strand gap. In most assays, the phenotype of Fancm mutants is less severe than that of Blm mutants, and the phenotype of Blm Fancm double mutants is more severe than either single mutant, indicating both overlapping and unique functions. It is thought that mitotic crossovers arise when structure-selective nucleases cleave DNA intermediates that would normally be unwound or disassembled by these helicases. When BLM is absent, three nucleases believed to function as Holliday junction resolvases—MUS81-MMS4, MUS312-SLX1, and GEN—become essential. In contrast, no single resolvase is essential in mutants lacking FANCM, although simultaneous loss of GEN and either of the others is lethal in Fancm mutants. Since Fancm mutants can tolerate loss of a single resolvase, we were able to show that spontaneous mitotic crossovers that occur when FANCM is missing are dependent on MUS312 and either MUS81 or SLX1. PMID:25205745

  13. Transverse localization of light in nonlinear photonic lattices with dimensionality crossover

    SciTech Connect

    Jovic, Dragana M.; Belic, Milivoj R.; Denz, Cornelia

    2011-10-15

    In a numerical study, we demonstrate the dimensionality crossover in Anderson localization of light. We consider crossover from the two-dimensional (2D) to the one-dimensional (1D) lattice, optically induced in both linear and nonlinear dielectric media. The joint influence of nonlinearity and disorder on Anderson localization in such systems is discussed in some detail. We find that, in the linear regime, the localization is more pronounced in two dimensions than in one dimension. We also find that the localization in the intermediate cases of crossover is less pronounced than in both the pure 1D and 2D cases in the linear regime, whereas in the nonlinear regime this depends on the strength of the nonlinearity. There exist strongly nonlinear regimes in which 1D localization is more pronounced than the 2D localization, opposite to the case of the linear regime. We find that the dimensionality crossover is characterized by two different localization lengths, whose behavior is different along different transverse directions.

  14. Thermal equation of state of lower-mantle ferropericlase across the spin crossover

    SciTech Connect

    Mao, Zhu; Lin, Jung-Fu; Liu, Jin; Prakapenka, Vitali B.

    2012-10-23

    The thermal equation of state of ferropericlase [(Mg{sub 0.75}Fe{sub 0.25})O] has been investigated by synchrotron X-ray diffraction up to 140 GPa and 2000 K in a laser-heated diamond anvil cell. Based on results at high pressure-temperature conditions, the derived phase diagram shows that the spin crossover widens at elevated temperatures. Along the lower-mantle geotherm, the spin crossover occurs between 1700 km and 2700 km depth. Compared to the high-spin state, thermoelastic modeling of the data shows a {approx}1.2% increase in density, a factor of two increase in thermal expansion coefficient over a range of 1000 km, and a maximum decrease of 37% and 13% in bulk modulus and bulk sound velocity, respectively, at {approx}2180 km depth across the spin crossover. These anomalous behaviors in the thermoelastic properties of ferropericlase across the spin crossover must be taken into account in order to understand the seismic signatures and geodynamics of the lower mantle.

  15. Tic Reduction with Risperidone Versus Pimozide in a Randomized, Double-Blind, Crossover Trial

    ERIC Educational Resources Information Center

    Gilbert, Donald L.; Batterson, J. Robert; Sethuraman, Gopalan; Sallee, Floyd R.

    2004-01-01

    Objective: To compare the tic suppression, electrocardiogram (ECG) changes, weight gain, and side effect profiles of pimozide versus risperidone in children and adolescents with tic disorders. Method: This was a randomized, double-blind, crossover (evaluable patient analysis) study. Nineteen children aged 7 to 17 years with Tourette's or chronic…

  16. Crossover and valence band Kβ X-rays of chromium oxides

    NASA Astrophysics Data System (ADS)

    Fazinić, Stjepko; Mandić, Luka; Kavčič, Matjaž; Božičević, Iva

    2011-06-01

    Kβ X-ray spectra of chromium metal and selected chromium oxides were measured twice using medium resolution flat crystal spectrometer and high resolution spectrometer employing Johansson geometry after excitation with 2 MeV proton beams. The positions and intensities of crossover ( Kβ″) and valence ( Kβ2,5) band X-rays relative to the primary Kβ X-ray components were extracted in a consistent way. The results were compared with the existing data obtained by proton and photon induced ionization mechanisms and theoretical predictions. The obtained results in peak relative positions and intensities were analyzed in order to study dependence on the chromium oxidation states and chromium-oxygen bond lengths in selected chromium oxides. Our results obtained by both spectrometers confirm that the linear trend observed for the valence peak relative energy shift as a function of chromium oxidation number does not depend on the experimental resolution. Experimental results for normalized intensities (i.e. relative intensities divided with the number of chromium-oxygen pairs) of crossover and valence band X-rays obtained by both spectrometers are in very good agreement, and follow exponential relationship with the average Cr―O bond lengths in corresponding chromium oxides. The observed trends in crossover and valence X-rays normalized intensities could be used to measure the average chromium-oxygen bond length in various chromium oxides, with the sum of both crossover and valence X-ray normalized intensities being the most sensitive measure.

  17. MICROSATELLITE DIVERSITY AND CROSSOVER REGIONS WITHIN HOMOZYGOUS AND HETEROZYGOUS SLA HAPLOTYPES OF DIFFERENT PIG BREEDS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Our aim was to investigate microsatellite (MS) diversity and find crossover regions at 42 polymorphic MS loci in the SLA genomic region of 72 pigs with different homozygous and heterozygous well-defined SLA haplotypes. We analyzed the genetic polymorphisms of the 42 MS markers in 23 SLA homozygous/h...

  18. A randomized crossover trial to decrease bacterial contamination on hospital scrubs.

    PubMed

    Boutin, Mallory A; Thom, Kerri A; Zhan, Min; Johnson, J Kristie

    2014-11-01

    Healthcare worker attire may become contaminated with pathogenic organisms during a normal shift. We performed a randomized crossover study to assess whether treatment with an antimicrobial coating would decrease bacterial contamination on scrubs. Thirty percent of all scrubs were contaminated; there was no difference in the rate of contamination between the intervention and control groups.

  19. 50 CFR 660.320 - Open access fishery-crossover provisions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Open access fishery-crossover provisions. 660.320 Section 660.320 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE (CONTINUED) FISHERIES OFF WEST COAST STATES West Coast Groundfish-Open Access Fisheries §...

  20. 50 CFR 660.320 - Open access fishery-crossover provisions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Open access fishery-crossover provisions. 660.320 Section 660.320 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE (CONTINUED) FISHERIES OFF WEST COAST STATES West Coast Groundfish-Open Access Fisheries...

  1. 50 CFR 660.220 - Fixed gear fishery-crossover provisions.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Fixed gear fishery-crossover provisions. 660.220 Section 660.220 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE (CONTINUED) FISHERIES OFF WEST COAST STATES West Coast Groundfish-Limited Entry Fixed...

  2. 50 CFR 660.220 - Fixed gear fishery-crossover provisions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Fixed gear fishery-crossover provisions. 660.220 Section 660.220 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE (CONTINUED) FISHERIES OFF WEST COAST STATES West Coast Groundfish-Limited Entry Fixed...

  3. 50 CFR 660.320 - Open access fishery-crossover provisions.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Open access fishery-crossover provisions. 660.320 Section 660.320 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE (CONTINUED) FISHERIES OFF WEST COAST STATES West Coast Groundfish-Open Access Fisheries §...

  4. 50 CFR 660.220 - Fixed gear fishery-crossover provisions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Fixed gear fishery-crossover provisions. 660.220 Section 660.220 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE (CONTINUED) FISHERIES OFF WEST COAST STATES West Coast Groundfish-Limited Entry Fixed...

  5. 50 CFR 660.220 - Fixed gear fishery-crossover provisions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Fixed gear fishery-crossover provisions. 660.220 Section 660.220 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE (CONTINUED) FISHERIES OFF WEST COAST STATES West Coast Groundfish-Limited Entry Fixed...

  6. 50 CFR 660.320 - Open access fishery-crossover provisions.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Open access fishery-crossover provisions. 660.320 Section 660.320 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE (CONTINUED) FISHERIES OFF WEST COAST STATES West Coast Groundfish-Open Access Fisheries §...

  7. 50 CFR 660.320 - Open access fishery-crossover provisions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Open access fishery-crossover provisions. 660.320 Section 660.320 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE (CONTINUED) FISHERIES OFF WEST COAST STATES West Coast Groundfish-Open Access Fisheries §...

  8. 50 CFR 660.220 - Fixed gear fishery-crossover provisions.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Fixed gear fishery-crossover provisions. 660.220 Section 660.220 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE (CONTINUED) FISHERIES OFF WEST COAST STATES West Coast Groundfish-Limited Entry Fixed...

  9. Two structural relaxations in protein hydration water and their dynamic crossovers.

    PubMed

    Camisasca, G; De Marzio, M; Corradini, D; Gallo, P

    2016-07-28

    We study the translational single particle dynamics of hydration water of lysozyme upon cooling by means of molecular dynamics simulations. We find that water close to the protein exhibits two distinct relaxations. By characterizing their behavior upon cooling, we are able to assign the first relaxation to the structural α-relaxation also present in bulk water and in other glass-forming liquids. The second, slower, relaxation can be ascribed to a dynamic coupling of hydration water motions to the fluctuations of the protein structure. Both relaxation times exhibit crossovers in the behavior upon cooling. For the α-process, we find upon cooling a crossover from a fragile behavior to a strong behavior at a temperature which is about five degrees higher than that of bulk water. The long-relaxation time appears strictly connected to the protein motion as it shows upon cooling a temperature crossover from a strong behavior with a lower activation energy to a strong behavior with a higher activation energy. The crossover temperature coincides with the temperature of the protein dynamical transition. These findings can help experimentalists to disentangle the different information coming from total correlators and to better characterize hydration water relaxations in different biomolecules. PMID:27475377

  10. Giant superconducting fluctuations in the compensated semimetal FeSe at the BCS–BEC crossover

    PubMed Central

    Kasahara, S.; Yamashita, T.; Shi, A.; Kobayashi, R.; Shimoyama, Y.; Watashige, T.; Ishida, K.; Terashima, T.; Wolf, T.; Hardy, F.; Meingast, C.; Löhneysen, H. v.; Levchenko, A.; Shibauchi, T.; Matsuda, Y.

    2016-01-01

    The physics of the crossover between weak-coupling Bardeen–Cooper–Schrieffer (BCS) and strong-coupling Bose–Einstein condensate (BEC) limits gives a unified framework of quantum-bound (superfluid) states of interacting fermions. This crossover has been studied in the ultracold atomic systems, but is extremely difficult to be realized for electrons in solids. Recently, the superconducting semimetal FeSe with a transition temperature Tc=8.5 K has been found to be deep inside the BCS–BEC crossover regime. Here we report experimental signatures of preformed Cooper pairing in FeSe, whose energy scale is comparable to the Fermi energies. In stark contrast to usual superconductors, large non-linear diamagnetism by far exceeding the standard Gaussian superconducting fluctuations is observed below T*∼20 K, providing thermodynamic evidence for prevailing phase fluctuations of superconductivity. Nuclear magnetic resonance and transport data give evidence of pseudogap formation at ∼T*. The multiband superconductivity along with electron–hole compensation in FeSe may highlight a novel aspect of the BCS–BEC crossover physics. PMID:27687782

  11. 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…

  12. Cycling Versus Continuous Mode In Neuromodulator Programming: A Crossover, Randomized, Controlled Trial.

    PubMed

    Beer, Gwendolyn M; Gurule, Margaret M; Komesu, Yuko M; Qualls, Clifford R; Rogers, Rebecca G

    2016-01-01

    This is a randomized, controlled, blind, crossover trial comparing cycling versus continuous programming of a sacral neuromodulator in women diagnosed with overactive bladder (OAB). At 6 months, treatment order significantly affected Overactive Bladder Questionnaire - Short Form (OABq-SF) symptom scores. The cycling followed by continuous stimulation group had superior OABq-SF scores (p > 0.02). PMID:27501593

  13. Spin crossover in liquid (Mg,Fe)O at extreme conditions

    NASA Astrophysics Data System (ADS)

    Holmström, E.; Stixrude, L.

    2016-05-01

    We use first-principles free-energy calculations to predict a pressure-induced spin crossover in the liquid planetary material (Mg,Fe)O, whereby the magnetic moments of Fe ions vanish gradually over a range of hundreds of GPa. Because electronic entropy strongly favors the nonmagnetic low-spin state of Fe, the crossover has a negative effective Clapeyron slope, in stark contrast to the crystalline counterpart of this transition-metal oxide. Diffusivity of liquid (Mg,Fe)O is similar to that of MgO, displaying a weak dependence on element and spin state. Fe-O and Mg-O coordination increases from approximately 4 to 7 as pressure goes from 0 to 200 GPa. We find partitioning of Fe to induce a density inversion between the crystal and melt, implying separation of a basal magma ocean from a surficial one in the early Earth. The spin crossover induces an anomaly into the density contrast, and the oppositely signed Clapeyron slopes for the crossover in the liquid and crystalline phases imply that the solid-liquid transition induces a spin transition in (Mg,Fe)O.

  14. AAA-ATPase FIDGETIN-LIKE 1 and Helicase FANCM Antagonize Meiotic Crossovers by Distinct Mechanisms

    PubMed Central

    Girard, Chloe; Chelysheva, Liudmila; Choinard, Sandrine; Froger, Nicole; Macaisne, Nicolas; Lehmemdi, Afef; Mazel, Julien; Crismani, Wayne; Mercier, Raphael

    2015-01-01

    Meiotic crossovers (COs) generate genetic diversity and are critical for the correct completion of meiosis in most species. Their occurrence is tightly constrained but the mechanisms underlying this limitation remain poorly understood. Here we identified the conserved AAA-ATPase FIDGETIN-LIKE-1 (FIGL1) as a negative regulator of meiotic CO formation. We show that Arabidopsis FIGL1 limits CO formation genome-wide, that FIGL1 controls dynamics of the two conserved recombinases DMC1 and RAD51 and that FIGL1 hinders the interaction between homologous chromosomes, suggesting that FIGL1 counteracts DMC1/RAD51-mediated inter-homologue strand invasion to limit CO formation. Further, depleting both FIGL1 and the previously identified anti-CO helicase FANCM synergistically increases crossover frequency. Additionally, we showed that the effect of mutating FANCM on recombination is much lower in F1 hybrids contrasting from the phenotype of inbred lines, while figl1 mutation equally increases crossovers in both contexts. This shows that the modes of action of FIGL1 and FANCM are differently affected by genomic contexts. We propose that FIGL1 and FANCM represent two successive barriers to CO formation, one limiting strand invasion, the other disassembling D-loops to promote SDSA, which when both lifted, leads to a large increase of crossovers, without impairing meiotic progression. PMID:26161528

  15. Iron(ii)-triazole core-shell nanocomposites: toward multistep spin crossover materials.

    PubMed

    Wang, Yu-Xia; Qiu, Dan; Xi, Sai-Fei; Ding, Zheng-Dong; Li, Zaijun; Li, Yunxing; Ren, Xuehong; Gu, Zhi-Guo

    2016-06-28

    The first SCO@SCO core-shell nanomaterials have been synthesized by the step-by-step microemulsion method. The observed gyroscopic core-shell nanocomposites exhibit three-step spin crossover behaviour with thermal hysteresis at around room temperature. This offers an efficient and novel strategy for the development of multistable SCO materials. PMID:27263855

  16. A Crossover Trial Evaluating an Educational-Behavioral Joint Protection Programme for People with Rheumatoid Arthritis.

    ERIC Educational Resources Information Center

    Hammond, A.; Lincoln, N.; Sutcliffe, L.

    1999-01-01

    Joint protection, a self-management technique taught to people with rheumatoid arthritis, was used in a group education program. A crossover trial (N=35) was conducted. No significant changes in measures of pain, functional disability, grip strength, self-efficacy or helplessness occurred post-education, although this may have been due to the…

  17. Spin crossover in ferropericlase and velocity heterogeneities in the lower mantle

    PubMed Central

    Wu, Zhongqing; Wentzcovitch, Renata M.

    2014-01-01

    Deciphering the origin of seismic velocity heterogeneities in the mantle is crucial to understanding internal structures and processes at work in the Earth. The spin crossover in iron in ferropericlase (Fp), the second most abundant phase in the lower mantle, introduces unfamiliar effects on seismic velocities. First-principles calculations indicate that anticorrelation between shear velocity (VS) and bulk sound velocity (Vφ) in the mantle, usually interpreted as compositional heterogeneity, can also be produced in homogeneous aggregates containing Fp. The spin crossover also suppresses thermally induced heterogeneity in longitudinal velocity (VP) at certain depths but not in VS. This effect is observed in tomography models at conditions where the spin crossover in Fp is expected in the lower mantle. In addition, the one-of-a-kind signature of this spin crossover in the RS/P (∂⁡ln⁡VS/∂⁡ln⁡VP) heterogeneity ratio might be a useful fingerprint to detect the presence of Fp in the lower mantle. PMID:25002507

  18. Two structural relaxations in protein hydration water and their dynamic crossovers

    NASA Astrophysics Data System (ADS)

    Camisasca, G.; De Marzio, M.; Corradini, D.; Gallo, P.

    2016-07-01

    We study the translational single particle dynamics of hydration water of lysozyme upon cooling by means of molecular dynamics simulations. We find that water close to the protein exhibits two distinct relaxations. By characterizing their behavior upon cooling, we are able to assign the first relaxation to the structural α-relaxation also present in bulk water and in other glass-forming liquids. The second, slower, relaxation can be ascribed to a dynamic coupling of hydration water motions to the fluctuations of the protein structure. Both relaxation times exhibit crossovers in the behavior upon cooling. For the α-process, we find upon cooling a crossover from a fragile behavior to a strong behavior at a temperature which is about five degrees higher than that of bulk water. The long-relaxation time appears strictly connected to the protein motion as it shows upon cooling a temperature crossover from a strong behavior with a lower activation energy to a strong behavior with a higher activation energy. The crossover temperature coincides with the temperature of the protein dynamical transition. These findings can help experimentalists to disentangle the different information coming from total correlators and to better characterize hydration water relaxations in different biomolecules.

  19. Crossover Equation of State Models Applied to the Critical Behavior of Xenon

    NASA Astrophysics Data System (ADS)

    Garrabos, Y.; Lecoutre, C.; Marre, S.; Guillaument, R.; Beysens, D.; Hahn, I.

    2015-03-01

    The turbidity () measurements of Güttinger and Cannell (Phys Rev A 24:3188-3201, 1981) in the temperature range along the critical isochore of homogeneous xenon are reanalyzed. The singular behaviors of the isothermal compressibility () and the correlation length () predicted from the master crossover functions are introduced in the turbidity functional form derived by Puglielli and Ford (Phys Rev Lett 25:143-146, 1970). We show that the turbidity data are thus well represented by the Ornstein-Zernike approximant, within 1 % precision. We also introduce a new crossover master model (CMM) of the parametric equation of state for a simple fluid system with no adjustable parameter. The CMM model and the phenomenological crossover parametric model are compared with the turbidity data and the coexisting liquid-gas density difference (). The excellent agreement observed for , , , and in a finite temperature range well beyond the Ising-like preasymptotic domain confirms that the Ising-like critical crossover behavior of xenon can be described in conformity with the universal features estimated by the renormalization-group methods. Only 4 critical coordinates of the vapor-liquid critical point are needed in the (pressure, temperature, molecular volume) phase surface of xenon.

  20. The Daily Spillover and Crossover of Emotional Labor: Faking Emotions at Work and at Home

    ERIC Educational Resources Information Center

    Sanz-Vergel, Ana Isabel; Rodriguez-Munoz, Alfredo; Bakker, Arnold B.; Demerouti, Evangelia

    2012-01-01

    This diary study among 75 Spanish dual earner couples investigates whether emotional labor performed by employees at work has implications for themselves and for their partner at home. On the basis of the Spillover-Crossover model, we hypothesized that individuals' surface acting at work would spill over to the home domain, and that surface acting…

  1. Toward higher nuclearity: tetranuclear cobalt(II) metallogrid exhibiting spin crossover.

    PubMed

    Wu, Shu-Qi; Wang, Yi-Tong; Cui, Ai-Li; Kou, Hui-Zhong

    2014-03-01

    Supramolecular strategy was employed to achieve the highest nuclearity Co(II) cluster exhibiting spin-crossover (SCO) behavior. Magnetic susceptibility characterization of the Co4(II) complex shows that two different spin-transition processes occur. The SCO behavior is directed by the partially deprotonated polydentate ligand, which favors the structural distortion required by the spin transition. PMID:24555696

  2. BCS-BEC crossover physics in FeSe bulk superconductor

    NASA Astrophysics Data System (ADS)

    Shibauchi, Takasada

    The physics of the crossover between weak-coupling Bardeen-Cooper-Schrieffer (BCS) and strong-coupling Bose-Einstein-condensate (BEC) limits gives a unified framework of quantum bound (superfluid) states of interacting fermions. This crossover has been studied in the ultracold atomic systems, but is extremely difficult to be realized for electrons in solids. Through the superfluid response, transport, thermoelectric response, and quantum oscillations, we demonstrate that the Fermi energy of the bulk superconductor FeSe is extremely small, with the ratio of the gap to Fermi energy is of the order of unity, which qualifies FeSe to be deep inside the BCS-BEC crossover regime. Thus FeSe appears to be a key material to solve the longstanding issue in the crossover physics; the presence of preformed Cooper pairs giving rise to a pseudogap above the superconducting transition temperature Tc. We report experimental signatures of preformed Cooper pairing well above Tc = 8 . 5 K in clean single crystals of FeSe. Our torque magnetometry reveals distinct diamagnetic signal below T* ~ 20 K indicating that the superconducting fluctuations above the transition temperature are strongly enhanced from the standard Gaussian theory. The transport and thermoelectric coefficients also exhibit distinct anomalies at ~T* , signaling a possible pseudogap formation. The multiband nature with the electron-hole compensation in FeSe may highlight a fundamentally new aspect of the BCS-BEC crossover physics In collaboration with S. Kasahara, T. Yamashita, Y. Matsuda (Kyoto), Y. Mizukami (Tokyo), T. Wolf, F. Hardy, C. Meingast, H. v. Löhneysen (KIT), M. D. Watson, A. I. Coldea (Oxford), T. Terashima (NIMS), W. Knafo (Toulouse), T. Hanaguri (Riken).

  3. Microscopic theory of cooperative spin crossover: Interaction of molecular modes with phonons

    SciTech Connect

    Palii, Andrew E-mail: klokishner@yahoo.com; Ostrovsky, Serghei; Reu, Oleg; Klokishner, Sophia E-mail: klokishner@yahoo.com; Tsukerblat, Boris; Decurtins, Silvio; Liu, Shi-Xia

    2015-08-28

    In this article, we present a new microscopic theoretical approach to the description of spin crossover in molecular crystals. The spin crossover crystals under consideration are composed of molecular fragments formed by the spin-crossover metal ion and its nearest ligand surrounding and exhibiting well defined localized (molecular) vibrations. As distinguished from the previous models of this phenomenon, the developed approach takes into account the interaction of spin-crossover ions not only with the phonons but also a strong coupling of the electronic shells with molecular modes. This leads to an effective coupling of the local modes with phonons which is shown to be responsible for the cooperative spin transition accompanied by the structural reorganization. The transition is characterized by the two order parameters representing the mean values of the products of electronic diagonal matrices and the coordinates of the local modes for the high- and low-spin states of the spin crossover complex. Finally, we demonstrate that the approach provides a reasonable explanation of the observed spin transition in the [Fe(ptz){sub 6}](BF{sub 4}){sub 2} crystal. The theory well reproduces the observed abrupt low-spin → high-spin transition and the temperature dependence of the high-spin fraction in a wide temperature range as well as the pronounced hysteresis loop. At the same time within the limiting approximations adopted in the developed model, the evaluated high-spin fraction vs. T shows that the cooperative spin-lattice transition proves to be incomplete in the sense that the high-spin fraction does not reach its maximum value at high temperature.

  4. Microscopic theory of cooperative spin crossover: Interaction of molecular modes with phonons

    NASA Astrophysics Data System (ADS)

    Palii, Andrew; Ostrovsky, Serghei; Reu, Oleg; Tsukerblat, Boris; Decurtins, Silvio; Liu, Shi-Xia; Klokishner, Sophia

    2015-08-01

    In this article, we present a new microscopic theoretical approach to the description of spin crossover in molecular crystals. The spin crossover crystals under consideration are composed of molecular fragments formed by the spin-crossover metal ion and its nearest ligand surrounding and exhibiting well defined localized (molecular) vibrations. As distinguished from the previous models of this phenomenon, the developed approach takes into account the interaction of spin-crossover ions not only with the phonons but also a strong coupling of the electronic shells with molecular modes. This leads to an effective coupling of the local modes with phonons which is shown to be responsible for the cooperative spin transition accompanied by the structural reorganization. The transition is characterized by the two order parameters representing the mean values of the products of electronic diagonal matrices and the coordinates of the local modes for the high- and low-spin states of the spin crossover complex. Finally, we demonstrate that the approach provides a reasonable explanation of the observed spin transition in the [Fe(ptz)6](BF4)2 crystal. The theory well reproduces the observed abrupt low-spin → high-spin transition and the temperature dependence of the high-spin fraction in a wide temperature range as well as the pronounced hysteresis loop. At the same time within the limiting approximations adopted in the developed model, the evaluated high-spin fraction vs. T shows that the cooperative spin-lattice transition proves to be incomplete in the sense that the high-spin fraction does not reach its maximum value at high temperature.

  5. 3-way Partnership Meets Social Need.

    ERIC Educational Resources Information Center

    Smith, Mary M.; McCune, Bonnie

    1979-01-01

    Describes a cooperative effort between the Community College of Denver, Red Rocks; a Denver health organization; and members of the business community to build Ronald McDonald House (temporary housing for families of hospitalized children) and in the process provide experiential learning for building trades students at Red Rocks. (LS)

  6. 3 Ways to Increase Positive Emotions

    MedlinePlus

    ... Ways to Be More Aware of Your Emotions Emotional Intelligence Understanding Your Emotions Contact Us Print Resources Send to a friend ... TeensHealth® is for educational purposes only. For specific medical advice, diagnoses, and ... Science Source Images, Shutterstock, and Clipart.com

  7. 3 Ways that Promote Student Reasoning

    ERIC Educational Resources Information Center

    Rathouz, Margaret

    2011-01-01

    Children are naturally curious and want to make sense of their world. To implement mathematical tasks that nurture children's desire to reason, it is valuable for teachers to have experienced for themselves comparable tasks and learning environments (Ball and Bass 2000). In this article, the author describes three strategies to facilitate…

  8. Crossover behavior of multiscale fluctuations in Big Data: Langevin model and substorm time-scales in Earth's magnetosphere

    NASA Astrophysics Data System (ADS)

    Sharma, A. S.; Setty, V. A.

    2015-12-01

    Multiscale fluctuations in large and complex data are usually characterized by a power law with a scaling exponent but many systems require more than one exponent and thus exhibit crossover behavior. The scaling exponents, such as Hurst exponents, represent the nature of correlation in the system and the crossover shows the presence of more than one type of correlation. An accurate characterization of the crossover behavior is thus needed for a better understanding of the inherent correlations in the system, and is an important method of Big Data analysis. A multi-step process is developed for accurate computation of the crossover behavior. First the detrended fluctuation analysis is used to remove the trends in the data and the scaling exponents are computed. The crossover point is then computed by a Hyperbolic regression technique, with no prior assumptions. The time series data of the magnetic field variations during substorms in the Earth's magnetosphere is analyzed with these techniques and yields a crossover behavior with a time scale of ~4 hrs. A Langevin model derived from the data provides an excellent fit to the crossover in the scaling exponents and a good model of magnetospheric dynamics. The combination of fluctuation analysis and mathematical modeling thus yields a comprehensive approach in the analysis of Big Data.

  9. Delay in the Detrended Fluctuation Analysis Crossover Point as a Risk Factor for Type 2 Diabetes Mellitus.

    PubMed

    Varela, Manuel; Vigil, Luis; Rodriguez, Carmen; Vargas, Borja; García-Carretero, Rafael

    2016-01-01

    Detrended Fluctuation Analysis (DFA) measures the complexity of a glucose time series obtained by means of a Continuous Glucose Monitoring System (CGMS) and has proven to be a sensitive marker of glucoregulatory dysfunction. Furthermore, some authors have observed a crossover point in the DFA, signalling a change of dynamics, arguably dependent on the beta-insular function. We investigate whether the characteristics of this crossover point have any influence on the risk of developing type 2 diabetes mellitus (T2DM). To this end we recruited 206 patients at increased risk of T2DM (because of obesity, essential hypertension, or a first-degree relative with T2DM). A CGMS time series was obtained, from which the DFA and the crossover point were calculated. Patients were then followed up every 6 months for a mean of 17.5 months, controlling for the appearance of T2DM diagnostic criteria. The time to crossover point was a significant predictor risk of developing T2DM, even after adjusting for other variables. The angle of the crossover was not predictive by itself but became significantly protective when the model also considered the crossover point. In summary, both a delay and a blunting of the crossover point predict the development of T2DM.

  10. Delay in the Detrended Fluctuation Analysis Crossover Point as a Risk Factor for Type 2 Diabetes Mellitus

    PubMed Central

    Varela, Manuel; Vigil, Luis; Rodriguez, Carmen; Vargas, Borja; García-Carretero, Rafael

    2016-01-01

    Detrended Fluctuation Analysis (DFA) measures the complexity of a glucose time series obtained by means of a Continuous Glucose Monitoring System (CGMS) and has proven to be a sensitive marker of glucoregulatory dysfunction. Furthermore, some authors have observed a crossover point in the DFA, signalling a change of dynamics, arguably dependent on the beta-insular function. We investigate whether the characteristics of this crossover point have any influence on the risk of developing type 2 diabetes mellitus (T2DM). To this end we recruited 206 patients at increased risk of T2DM (because of obesity, essential hypertension, or a first-degree relative with T2DM). A CGMS time series was obtained, from which the DFA and the crossover point were calculated. Patients were then followed up every 6 months for a mean of 17.5 months, controlling for the appearance of T2DM diagnostic criteria. The time to crossover point was a significant predictor risk of developing T2DM, even after adjusting for other variables. The angle of the crossover was not predictive by itself but became significantly protective when the model also considered the crossover point. In summary, both a delay and a blunting of the crossover point predict the development of T2DM. PMID:27294154

  11. Repetitive transcranial magnetic stimulation over the orbitofrontal cortex for obsessive-compulsive disorder: a double-blind, crossover study

    PubMed Central

    Nauczyciel, C; Le Jeune, F; Naudet, F; Douabin, S; Esquevin, A; Vérin, M; Dondaine, T; Robert, G; Drapier, D; Millet, B

    2014-01-01

    This pilot study was designed to assess the efficacy of low-frequency repetitive transcranial magnetic stimulation (rTMS) over the right orbitofrontal cortex (OFC) by means of a double-cone coil in patients suffering from obsessive-compulsive disorder. We hypothesized that low-frequency stimulation of the OFC would lead to a reduction in clinical symptoms, as measured on the Yale-Brown Obsessive Compulsive Scale (Y-BOCS). A randomized, double-blind, crossover design was implemented with two 1-week treatment periods (active stimulation versus sham stimulation) separated by a 1-month washout period. Concomitantly, a subgroup of patients underwent a positron emission tomography (PET) scan after each stimulation sequence. Statistical analyses compared the Y-BOCS scores at the end of each period. At day 7, we observed a significant decrease from baseline in the Y-BOCS scores, after both active (P<0.01) and sham stimulation (P=0.02). This decrease tended to be larger after active stimulation than after sham stimulation: −6 (−29, 0) points versus −2 (−20, 4) points (P=0.07). Active versus sham PET scan contrasts showed that stimulation was related to a bilateral decrease in the metabolism of the OFC. The OFC should definitely be regarded as a key neuroanatomical target for rTMS, as it is easier to reach than either the striatum or the subthalamic nucleus, structures favored in neurosurgical approaches. PMID:25203167

  12. Dimensional Crossover of Thermal Transport in Hybrid Boron Nitride Nanostructures.

    PubMed

    Sakhavand, Navid; Shahsavari, Rouzbeh

    2015-08-26

    Although boron nitride nanotubes (BNNT) and hexagonal-BN (hBN) are superb one-dimensional (1D) and 2D thermal conductors respectively, bringing this quality into 3D remains elusive. Here, we focus on pillared boron nitride (PBN) as a class of 3D BN allotropes and demonstrate how the junctions, pillar length and pillar distance control phonon scattering in PBN and impart tailorable thermal conductivity in 3D. Using reverse nonequilibrium molecular dynamics simulations, our results indicate that although a clear phonon scattering at the junctions accounts for the lower thermal conductivity of PBN compared to its parent BNNT and hBN allotropes, it acts as an effective design tool and provides 3D thermo-mutable features that are absent in the parent structures. Propelled by the junction spacing, while one geometrical parameter, e.g., pillar length, controls the thermal transport along the out-of-plane direction of PBN, the other parameter, e.g., pillar distance, dictates the gross cross-sectional area, which is key for design of 3D thermal management systems. Furthermore, the junctions have a more pronounced effect in creating a Kapitza effect in the out-of-plane direction, due to the change in dimensionality of the phonon transport. This work is the first report on thermo-mutable properties of hybrid BN allotropes and can potentially impact thermal management of other hybrid 3D BN architectures. PMID:26158661

  13. 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.

  14. Topical Nasal Anesthesia in Flexible Bronchoscopy – A Cross-Over Comparison between Two Devices

    PubMed Central

    Fuehner, Thomas; Fuge, Jan; Jungen, Meike; Buck, Anna; Suhling, Hendrik; Welte, Tobias; Gottlieb, Jens; Greer, Mark

    2016-01-01

    Introduction Topical airway anesthesia is known to improve tolerance and patient satisfaction during flexible bronchoscopy (FB). Lidocaine is commonly used, delivered as an atomized spray. The current study assesses safety and patient satisfaction for nasal anesthesia of a new atomization device during outpatient bronchoscopy in lung transplant recipients. Methods Using a prospective, non-blinded, cross-over design, patients enrolled between 01-10-2014 and 24-11-2014 received 2% lidocaine using the standard reusable nasal atomizer (CRNA). Those enrolled between 25-11-2014 and 30-01-2015, received a disposable intranasal mucosal atomization device (DIMAD). After each procedure, the treating physician, their assistant and the patient independently rated side-effects and satisfaction, basing their responses on visual analogue scales (VAS). At their next scheduled bronchoscopy during the study period, patients then received the alternative atomizer. Written consent was obtained prior to the first bronchoscopy, and the study approved by the institutional ethics committee. Results Of the 252 patients enrolled between 01-10-2014 and 30-01-2015, 80 (32%) received both atomizers. Physicians reported better efficacy (p = 0.001) and fewer side effects (p< = 0.001) for DIMAD in patients exposed to both procedures. Among patients with one visit, physicians and their assistants reported improved efficacy (p = 0.018, p = 0.002) and fewer side effects (p< = 0.001, p = 0.029) for the disposable atomizer, whereas patients reported no difference in efficacy or side effects (p = 0.72 and p = 0.20). No severe adverse events were noted. The cost of the reusable device was 4.08€ per procedure, compared to 3.70€ for the disposable device. Discussion Topical nasal anesthesia via a disposable intranasal mucosal atomization device (DIMAD) offers comparable safety and patient comfort, compared to conventional reusable nasal atomizers (CRNA) in lung transplant recipients. Procedural costs

  15. Effect of eplerenone on insulin action in essential hypertension: a randomised, controlled, crossover study.

    PubMed

    McMurray, E M; Wallace, I R; Ennis, C; Hunter, S J; Atkinson, A B; Bell, P M

    2014-10-01

    An association exists between hyperaldosteronism, hypertension and impaired insulin action. Eplerenone is a selective mineralocorticoid receptor antagonist; however, little is known about its effects on insulin action. The aim of this study was to determine the effect of eplerenone on insulin action in hypertensive adults, using the hyperinsulinaemic euglycaemic clamp. A randomised, controlled, double-blind, crossover design was employed. After a 6-week washout period, hypertensive, non-diabetic patients were treated with either eplerenone 25 mg twice daily or doxazosin 2 mg twice daily for 12 weeks. After each treatment period, insulin action was assessed by a hyperinsulinaemic euglycaemic clamp, with isotope dilution methodology. After washout, treatment groups were crossed over. Fifteen patients completed the study. There were no differences in fasting glucose, or fasting insulin between treatment with eplerenone or doxazosin. The measure of overall insulin sensitivity, exogenous glucose infusion rates during the last 30 min of the clamp, was similar with both treatments; 23.4 (3.9) μmol kg(-1) min(-1) after eplerenone and 23.3 (3.6) μmol kg(-1) min(-1) after doxazosin (P=0.83). Isotopically determined fasting endogenous glucose production rates were similar after both treatments (eplerenone 9.4 (0.6) μmol kg(-1) min(-1) vs doxazosin 10.6 (0.7) μmol kg(-1) min(-1)). There was a trend for lower endogenous glucose production rates during hyperinsulinaemia following eplerenone compared with doxazosin (2.0 (0.8) μmol kg(-1) min(-1) vs 4.1 (0.9) μmol kg(-1) min(-1)). There was no difference in insulin stimulated peripheral glucose utilisation rates after treatment with eplerenone or doxazosin (25.4 (3.6) μmol kg(-1) min(-1) vs 27.0 (3.9) μmol kg(-1) min(-1)). This study gives reassuring evidence of the neutral effect of eplerenone on insulin action in hypertensive, non-diabetic patients.

  16. 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

  17. Inversion for Refractivity Parameters Using a Dynamic Adaptive Cuckoo Search with Crossover Operator Algorithm.

    PubMed

    Zhang, Zhihua; Sheng, Zheng; Shi, Hanqing; Fan, Zhiqiang

    2016-01-01

    Using the RFC technique to estimate refractivity parameters is a complex nonlinear optimization problem. In this paper, an improved cuckoo search (CS) algorithm is proposed to deal with this problem. To enhance the performance of the CS algorithm, a parameter dynamic adaptive operation and crossover operation were integrated into the standard CS (DACS-CO). Rechenberg's 1/5 criteria combined with learning factor were used to control the parameter dynamic adaptive adjusting process. The crossover operation of genetic algorithm was utilized to guarantee the population diversity. The new hybrid algorithm has better local search ability and contributes to superior performance. To verify the ability of the DACS-CO algorithm to estimate atmospheric refractivity parameters, the simulation data and real radar clutter data are both implemented. The numerical experiments demonstrate that the DACS-CO algorithm can provide an effective method for near-real-time estimation of the atmospheric refractivity profile from radar clutter. PMID:27212938

  18. Inversion for Refractivity Parameters Using a Dynamic Adaptive Cuckoo Search with Crossover Operator Algorithm.

    PubMed

    Zhang, Zhihua; Sheng, Zheng; Shi, Hanqing; Fan, Zhiqiang

    2016-01-01

    Using the RFC technique to estimate refractivity parameters is a complex nonlinear optimization problem. In this paper, an improved cuckoo search (CS) algorithm is proposed to deal with this problem. To enhance the performance of the CS algorithm, a parameter dynamic adaptive operation and crossover operation were integrated into the standard CS (DACS-CO). Rechenberg's 1/5 criteria combined with learning factor were used to control the parameter dynamic adaptive adjusting process. The crossover operation of genetic algorithm was utilized to guarantee the population diversity. The new hybrid algorithm has better local search ability and contributes to superior performance. To verify the ability of the DACS-CO algorithm to estimate atmospheric refractivity parameters, the simulation data and real radar clutter data are both implemented. The numerical experiments demonstrate that the DACS-CO algorithm can provide an effective method for near-real-time estimation of the atmospheric refractivity profile from radar clutter.

  19. Nucleation of spontaneous vortices in trapped Fermi gases undergoing a BCS-BEC crossover.

    SciTech Connect

    Glatz, A.; Roberts, H.; Aranson, I. S.; Levin, K.

    2011-01-01

    We study the spontaneous formation of vortices during the superfluid condensation in a trapped fermionic gas subjected to a rapid thermal quench via evaporative cooling. Our work is based on the numerical solution of the time-dependent crossover Ginzburg-Landau equation coupled to the heat diffusion equation. We quantify the evolution of condensate density and vortex length as a function of a crossover phase parameter from BCS to BEC. The more interesting phenomena occur somewhat nearer to the BEC regime and should be experimentally observable; during the propagation of the cold front, the increase in condensate density leads to the formation of supercurrents toward the center of the condensate as well as possible condensate volume oscillations.

  20. Modified Fermi sphere, pairing gap, and critical temperature for the BCS-BEC crossover

    SciTech Connect

    Floerchinger, S.; Wetterich, C.; Scherer, M. M.

    2010-06-15

    We investigate the phase diagram of two-component fermions in the BCS-BEC (Bose-Einstein condensate) crossover. Using functional renormalization-group equations we calculate the effect of quantum fluctuations on the fermionic self-energy parametrized by a wave-function renormalization, an effective Fermi radius, and the gap. This allows us to follow the modifications of the Fermi surface and the dispersion relation for fermionic excitations throughout the whole crossover region. We also determine the critical temperature of the second-order phase transition to superfluidity. Our results are in agreement with BCS theory including Gorkov's correction for a small negative scattering length a and with an interacting Bose gas for a small positive a. At the unitarity point the result for the gap at zero temperature agrees well with quantum Monte Carlo simulations, while the critical temperature differs.

  1. Guest tunable structure and spin crossover properties in a nanoporous coordination framework material.

    SciTech Connect

    Neville, S. M.; Halder, G. J.; Chapman, K. W.; Duriska, M. B.; Moubaraki, B.; Murray, K. S.; Kepert, C. J.

    2009-08-11

    The electronic switching properties of the nanoporous spin crossover framework [Fe(NCS){sub 2}(bpbd){sub 2}] {center_dot} x(guest), SCOF-2, can be rationally manipulated via sorption of a range of molecular guests (acetone, ethanol, methanol, propanol, 1-acetonitrile) into the 1-D channels of this material. Pronounced changes to the spin crossover properties are related directly to the steric and electronic influence of the individual guests: the degree of lattice cooperativity, as reflected in the abruptness of the transition and presence of hysteresis, is strongly influenced by the presence of cooperative host-guest interactions, and the temperature of the transition varies with guest polarity through a proposed electrostatic interaction.

  2. Inequity in work and intimate relationships: a Spillover-Crossover model.

    PubMed

    Bakker, Arnold B; Petrou, Paraskevas; Tsaousis, Ioannis

    2012-01-01

    This study among 267 Greek teachers and their partners tested and expanded the recently proposed Spillover-Crossover model (SCM) of well-being. Accordingly, experiences built up at work spill over to the home domain, and then influence the partner. The authors integrated equity theory in the model by formulating hypotheses about exchange in interpersonal relationships. Structural equation modeling analyses supported the spillover hypothesis that teachers who lose their work engagement as a result of an inequitable relationship with their students invest less in the relationship with their partner. In addition, the results supported the crossover hypothesis that teachers' relationship investments, in turn, show a negative relationship with inequity in the intimate relationship as perceived by the partner; and inequity in the intimate relationship contributed to partner depression. The findings are discussed in light of the SCM of well-being. PMID:22059998

  3. Beyond Tanner's Law: Crossover between Spreading Regimes of a Viscous Droplet on an Identical Film

    NASA Astrophysics Data System (ADS)

    Cormier, Sara L.; McGraw, Joshua D.; Salez, Thomas; Raphaël, Elie; Dalnoki-Veress, Kari

    2012-10-01

    We present results on the leveling of polymer microdroplets on thin films prepared from the same material. In particular, we explore the crossover from a droplet spreading on an infinitesimally thin film (Tanner’s law regime) to that of a droplet leveling on a film thicker than the droplet itself. In both regimes, the droplet’s excess surface area decreases towards the equilibrium configuration of a flat liquid film, but with a different power law in time. Additionally, the characteristic leveling time depends on molecular properties, the size of the droplet, and the thickness of the underlying film. Flow within the film makes this system fundamentally different from a droplet spreading on a solid surface. We thus develop a theoretical model based on thin film hydrodynamics that quantitatively describes the observed crossover between the two leveling regimes.

  4. Crossover from negative to positive magnetoresistance in the double quantum well system with different starting disorder.

    PubMed

    Kannan, E S; Karamad, M; Kim, Gil-Ho; Farrer, I; Ritchie, D A

    2010-02-01

    Magnetotransport measurements were performed in two widely separated double quantum well systems with different starting disorders. In the weak magnetic field regime, a crossover from negative to positive magnetoresistance in the longitudinal resistivity was observed in the system with weak disorder when the electron densities in the neighboring wells were significantly unbalanced. The crossover was found to be the result of the exchange-energy-assisted interactions between the electrons occupying the lowest subbands in the neighboring wells. In the case of the system with strong disorder short range scattering dominated the scattering process and no such transition in longitudinal resistivity in the low magnetic field regime was observed. However, at high magnetic fields, sharp peaks were observed in the Hall resistance due to the interaction between the edge states in the quantum Hall regime.

  5. Crossover from random three-dimensional avalanches to correlated nano shear bands in metallic glasses.

    PubMed

    Krisponeit, Jon-Olaf; Pitikaris, Sebastian; Avila, Karina E; Küchemann, Stefan; Krüger, Antje; Samwer, Konrad

    2014-04-10

    When applying mechanical stress to a bulk metallic glass it responds with elastic and/or plastic deformations. A comprehensive microscopic theory for the plasticity of amorphous solids remains an open task. Shear transformation zones consisting of dozens of atoms have been identified as smallest units of deformation. The connexion between local formation of shear transformations zones and the creation of macroscopic shear bands can be made using statistical analysis of stress/energy drops or strain slips during mechanical loading. Numerical work has proposed a power law dependence of those energy drops. Here we present an approach to circumvent the experimental resolution problem using a waiting time analysis. We report on the power law-distributed deformation behaviour and the observation of a crossover in the waiting times statistics. This crossover indicates a transition in the plastic deformation behaviour from three-dimensional random activity to a two-dimensional nano shear band sliding.

  6. Induced interaction in a Fermi gas with a BEC-BCS crossover

    SciTech Connect

    Yu Zengqiang; Huang Kun; Yin Lan

    2009-05-15

    We study the effect of the induced interaction on the superfluid transition temperature of a Fermi gas with a Bose-Einstein condensation-Bardeen-Cooper-Schrieffer (BEC-BCS) crossover. The Gorkov-Melik-Barkhudarov theory about the induced interaction is extended from the BCS side to the entire crossover and the pairing fluctuation is treated in the approach by Nozieres and Schmitt-Rink. At unitarity, the induced interaction reduces the transition temperature by about 20%. In the BCS limit, the transition temperature is reduced by a factor of about 2.22, as found by Gorkov and Melik-Barkhudarov. Our result shows that the effect of the induced interaction is important both on the BCS side and in the unitary region.

  7. Polymorphism in the spin-crossover ferric complexes [(TPA)Fe(III)(TCC)]PF6.

    PubMed

    Collet, Eric; Boillot, Marie Laure; Hebert, Johan; Moisan, Nicolas; Servol, Marina; Lorenc, Maciej; Toupet, Loïc; Buron-Le Cointe, Marylise; Tissot, Antoine; Sainton, Joelle

    2009-08-01

    We have identified two polymorphs of the molecular complex [(TPA)Fe((III))(TCC)]PF(6) [TPA = tris(2-pyridylmethyl)amine and TCC = 3,4,5,6-tetrachlorocatecholate dianion]: one is monoclinic and the other is orthorhombic. By lowering the temperature both undergo a thermal spin-crossover between a high-spin (S = 5/2) and a low-spin (S = 1/2) state, which we detected by magnetic, optical and X-ray diffraction measurements. The thermal crossover is only slightly shifted between the polymorphs. Their crystalline structures consist of similar cation layers alternating with PF(6) anion layers, packed differently in the two polymorphs. The magnetic and optical properties of the polymorphs are presented.

  8. Motion of a solitonic vortex in the BEC-BCS crossover.

    PubMed

    Ku, Mark J H; Ji, Wenjie; Mukherjee, Biswaroop; Guardado-Sanchez, Elmer; Cheuk, Lawrence W; Yefsah, Tarik; Zwierlein, Martin W

    2014-08-01

    We observe a long-lived solitary wave in a superfluid Fermi gas of (6)Li atoms after phase imprinting. Tomographic imaging reveals the excitation to be a solitonic vortex, oriented transverse to the long axis of the cigar-shaped atom cloud. The precessional motion of the vortex is directly observed, and its period is measured as a function of the chemical potential in the BEC-BCS crossover. The long period and the correspondingly large ratio of the inertial to the bare mass of the vortex are in good agreement with estimates based on superfluid hydrodynamics that we derive here using the known equation of state in the BEC-BCS crossover.

  9. Inversion for Refractivity Parameters Using a Dynamic Adaptive Cuckoo Search with Crossover Operator Algorithm

    PubMed Central

    Zhang, Zhihua; Sheng, Zheng; Shi, Hanqing; Fan, Zhiqiang

    2016-01-01

    Using the RFC technique to estimate refractivity parameters is a complex nonlinear optimization problem. In this paper, an improved cuckoo search (CS) algorithm is proposed to deal with this problem. To enhance the performance of the CS algorithm, a parameter dynamic adaptive operation and crossover operation were integrated into the standard CS (DACS-CO). Rechenberg's 1/5 criteria combined with learning factor were used to control the parameter dynamic adaptive adjusting process. The crossover operation of genetic algorithm was utilized to guarantee the population diversity. The new hybrid algorithm has better local search ability and contributes to superior performance. To verify the ability of the DACS-CO algorithm to estimate atmospheric refractivity parameters, the simulation data and real radar clutter data are both implemented. The numerical experiments demonstrate that the DACS-CO algorithm can provide an effective method for near-real-time estimation of the atmospheric refractivity profile from radar clutter. PMID:27212938

  10. Schema theory for genetic programming with one-point crossover and point mutation.

    PubMed

    Poli, R; Langdon, W B

    1998-01-01

    We review the main results obtained in the theory of schemata in genetic programming (GP), emphasizing their strengths and weaknesses. Then we propose a new, simpler definition of the concept of schema for GP, which is closer to the original concept of schema in genetic algorithms (GAs). Along with a new form of crossover, one-point crossover, and point mutation, this concept of schema has been used to derive an improved schema theorem for GP that describes the propagation of schemata from one generation to the next. We discuss this result and show that our schema theorem is the natural counterpart for GP of the schema theorem for GAs, to which it asymptotically converges.

  11. Crossover behavior of the thermal conductance and Kramers' transition rate theory

    NASA Astrophysics Data System (ADS)

    Sahu, Subin; Velizhanin, Kirill; Chien, Chih-Chun; Dubi, Yonatan; Zwolak, Michael

    2015-03-01

    Heat transport plays opposing roles in nanotechnology, hindering the miniaturization of electronics on one hand and forming the core of novel heattronic devices on the other. Moreover, heat transport in one-dimensional nanostructures has become a central tool in studying the onset of Fourier's law of heat conduction, a yet unresolved puzzle in theoretical physics. We study the paradigmatic setting of heat transport in one-dimensional systems, a lattice coupled to two heat baths held at different temperatures. Using both numerical and analytical tools, we demonstrate that the heat conductance displays a crossover behavior as the coupling to the thermal reservoirs is tuned. We provide evidence that this behavior is universal by examining harmonic, anharmonic, and disordered systems, and discuss the origin of this effect using an analogy with Kramers' transition state theory for chemical reaction rates. This crossover behavior has important implications in the analysis of numerical results, and suggests a novel way to tune the conductance in nanoscale devices.

  12. On correcting radial orbit errors for altimetric satellites using crossover analysis

    NASA Technical Reports Server (NTRS)

    Fu, Lee-Lueng; Vazquez, Jorge

    1988-01-01

    A method is proposed for correcting radial orbit error in measurements of sea surface height using a satellite altimeter. Traditionally, the orbit error is modeled in terms of a Fourier series with the Fourier coefficients determined by minimizing the residual crossover difference in a least-squares sense. In this method an a priori constraint must be imposed to obtain a unique solution. It is shown that by using singular value decomposition, no such constraint is needed. This proposed method leaves the geographically dependent errors unchanged and makes only those corrections warranted by the information contained in crossover differences. Thus, the resultant ocean topography is free from any undue distortion which might be incurred by an a priori constraint. It is suggested that the method is useful for application to high-accuracy altimetric mission, because the orbit error can be reduced without compromising the accuracy of the measured mean ocean topography.

  13. A sphere-cut-splice crossover for the evolution of cluster structures

    NASA Astrophysics Data System (ADS)

    Chen, Zhanghui; Jiang, Xiangwei; Li, Jingbo; Li, Shushen

    2013-06-01

    A new crossover operator is proposed to evolve the structures of the atomic clusters. It uses a sphere rather than a plane to cut and splice the parent structures. The child cluster is constructed by the atoms of one parent which lie inside the sphere, and the atoms of the other parent which lie outside the sphere. It can reliably produce reasonable offspring and preserve the good schemata in parent structures, avoiding the drawbacks of the classical plane-cut-splice crossover in the global searching ability and the local optimization speed. Results of Lennard-Jones clusters (30 ⩽ N ⩽ 500) show that at the same settings the genetic algorithm with the sphere-cut-splice crossover exhibits better performance than the one with the plane-cut-splice crossover. The average number of local minimizations needed to find the global minima and the average number of energy evaluation of each local minimization in the sphere scheme is 0.8075 and 0.8386 of that in the plane scheme, respectively. The mean speed-up ratio for the entire testing clusters reaches 1.8207. Moreover, the sphere scheme is particularly suitable for large clusters and the mean speed-up ratio reaches 2.3520 for the clusters with 110 ⩽ N ⩽ 500. The comparison with other successful methods in previous studies also demonstrates its good performance. Finally, a further analysis is presented on the statistical features of the cutting sphere and a modified strategy that reduces the probability of using tiny and large spheres exhibits better global search.

  14. Critical velocity for superfluid flow across the BEC-BCS crossover.

    PubMed

    Miller, D E; Chin, J K; Stan, C A; Liu, Y; Setiawan, W; Sanner, C; Ketterle, W

    2007-08-17

    Critical velocities have been observed in an ultracold superfluid Fermi gas throughout the BEC-BCS crossover. A pronounced peak of the critical velocity at unitarity demonstrates that superfluidity is most robust for resonant atomic interactions. Critical velocities were determined from the abrupt onset of dissipation when the velocity of a moving one-dimensional optical lattice was varied. The dependence of the critical velocity on lattice depth and on the inhomogeneous density profile was studied.

  15. Evolution of fermionic superfluid across the crossover from three to two dimensions

    NASA Astrophysics Data System (ADS)

    Ghosh, Sudeep Kumar; Shenoy, Vijay B.

    2013-03-01

    Motivated by recent experiments on the evolution of superfluid pairing from three to two dimensions, we construct and study a Bogoliubov-de Gennes theory that accurately accounts for the periodic potential that induces this dimensional crossover. We also obtain the anisotropic superfluid density tensor by a study of fluctuations. We investigate the thermal evolution of the superfluid state. Our results include temperature dependent radio frequency spectra of fermions along with a comparison with recent experiments. Work supported by CSIR, DST, DAE India

  16. Simulation of multi-steps thermal transition in 2D spin-crossover nanoparticles

    NASA Astrophysics Data System (ADS)

    Jureschi, Catalin-Maricel; Pottier, Benjamin-Louis; Linares, Jorge; Richard Dahoo, Pierre; Alayli, Yasser; Rotaru, Aurelian

    2016-04-01

    We have used an Ising like model to study the thermal behavior of a 2D spin crossover (SCO) system embedded in a matrix. The interaction parameter between edge SCO molecules and its local environment was included in the standard Ising like model as an additional term. The influence of the system's size and the ratio between the number of edge molecules and the other molecules were also discussed.

  17. Crossover from capillary fingering to viscous fingering for immiscible unstable flow:Experiment and modeling.

    PubMed

    Ferer, M; Ji, Chuang; Bromhal, Grant S; Cook, Joshua; Ahmadi, Goodarz; Smith, Duane H

    2004-01-01

    Invasion percolation with trapping (IPT) and diffusion-limited aggregation (DLA) are simple fractal models, which are known to describe two-phase flow in porous media at well defined, but unphysical limits of the fluid properties and flow conditions. A decade ago, Fernandez, Rangel, and Rivero predicted a crossover from IPT (capillary fingering) to DLA (viscous fingering) for the injection of a zero-viscosity fluid as the injection velocity was increased from zero. [Phys. Rev. Lett. 67, 2958 (1991)

  18. Chorionic gonadotropin in weight control. A double-blind crossover study.

    PubMed

    Young, R L; Fuchs, R J; Woltjen, M J

    1976-11-29

    Two hundred two patients participated in a double-blind random cross-over study of the effectiveness of human chorionic gonadotropin (HCG) vs placebo in a wieght reduction program. Serial measurements were made of weight, skin-fold thickness, dropout rates, reasons for dropping out, and patient subjective response. There was no statistically significant difference between those receiving HCG vs placebo during any phase of this study (P greater than .1). PMID:792477

  19. Thiazolylimines as novel ligand-systems for spin-crossover centred near room temperature.

    PubMed

    Struch, N; Wagner, N; Schnakenburg, G; Weisbarth, R; Klos, S; Beck, J; Lützen, A

    2016-09-28

    A new thiazolylimine ligand system for iron(ii) complexes which stabilises spin-crossover in solution and solid states with T1/2 temperatures around room temperature has been developed. This effect is studied in solution and solid states. Furthermore crystal packing effects are investigated offering a variety of T1/2 and even hysteresis centred at -3 °C in the solid state. PMID:27534997

  20. Ketazolam once daily for spasticity: double-blind cross-over study.

    PubMed

    Basmajian, J V; Shankardass, K; Russell, D

    1986-08-01

    This double-blind cross-over study of 14 severely spastic inpatients with chronic multiple sclerosis reveals that once-daily doses of ketazolam, a new drug, are effective in reducing spasticity in a significant proportion of patients without significant side-effects. Added to the similar findings of an earlier double-blind controlled study of divided doses, the results suggest that this special feature of ketazolam provides a unique flexibility that may be exploited in individual cases.

  1. Activation barrier scaling and crossover for noise-induced switching in micromechanical parametric oscillators.

    PubMed

    Chan, H B; Stambaugh, C

    2007-08-10

    We explore fluctuation-induced switching in parametrically driven micromechanical torsional oscillators. The oscillators possess one, two, or three stable attractors depending on the modulation frequency. Noise induces transitions between the coexisting attractors. Near the bifurcation points, the activation barriers are found to have a power law dependence on frequency detuning with critical exponents that are in agreement with predicted universal scaling relationships. At large detuning, we observe a crossover to a different power law dependence with an exponent that is device specific.

  2. Thiazolylimines as novel ligand-systems for spin-crossover centred near room temperature.

    PubMed

    Struch, N; Wagner, N; Schnakenburg, G; Weisbarth, R; Klos, S; Beck, J; Lützen, A

    2016-09-28

    A new thiazolylimine ligand system for iron(ii) complexes which stabilises spin-crossover in solution and solid states with T1/2 temperatures around room temperature has been developed. This effect is studied in solution and solid states. Furthermore crystal packing effects are investigated offering a variety of T1/2 and even hysteresis centred at -3 °C in the solid state.

  3. Diagnostic crossover from obesity to atypical anorexia nervosa - a case report.

    PubMed

    Wolter, Heike; Schneider, Nora; Pfeiffer, Ernst; Lehmkuhl, Ulrike

    2009-01-01

    A 15-year-old, female, formerly obese adolescent was referred to our day care clinic due to self-induced massive weight loss and depressive symptoms. Intense treatment, additional dialectical behavioral therapy and psychopharmacological treatment prevented further weight loss and improved her affective state. Due to remaining anorexic symptoms such as body image distortion, outpatient psychotherapeutic treatment is continued. This case report indicates the importance of further research on diagnostic crossover from obesity to atypical anorexia nervosa. PMID:20054205

  4. Formation of longitudinal patterns and dimensionality crossover of nonlinear spin waves in ferromagnetic stripes

    NASA Astrophysics Data System (ADS)

    Demidov, V. E.; Hansen, U.-F.; Dzyapko, O.; Koulev, N.; Demokritov, S. O.; Slavin, A. N.

    2006-09-01

    Formation of stationary longitudinal amplitude patterns by propagating nonlinear spin waves has been discovered and studied experimentally by means of space-resolved Brillouin light scattering spectroscopy. The pattern formation is observed for spin waves propagating in narrow, longitudinally magnetized yttrium iron garnet stripes, characterized by attractive nonlinearity in both the longitudinal and transverse directions. A clear crossover of the effective dimensionality describing the propagation of spin waves in the stripe is observed with increase of the wave amplitude.

  5. Molecular-scale dynamics of light-induced spin cross-over in a two-dimensional layer.

    PubMed

    Bairagi, Kaushik; Iasco, Olga; Bellec, Amandine; Kartsev, Alexey; Li, Dongzhe; Lagoute, Jérôme; Chacon, Cyril; Girard, Yann; Rousset, Sylvie; Miserque, Frédéric; Dappe, Yannick J; Smogunov, Alexander; Barreteau, Cyrille; Boillot, Marie-Laure; Mallah, Talal; Repain, Vincent

    2016-01-01

    Spin cross-over molecules show the unique ability to switch between two spin states when submitted to external stimuli such as temperature, light or voltage. If controlled at the molecular scale, such switches would be of great interest for the development of genuine molecular devices in spintronics, sensing and for nanomechanics. Unfortunately, up to now, little is known on the behaviour of spin cross-over molecules organized in two dimensions and their ability to show cooperative transformation. Here we demonstrate that a combination of scanning tunnelling microscopy measurements and ab initio calculations allows discriminating unambiguously between both states by local vibrational spectroscopy. We also show that a single layer of spin cross-over molecules in contact with a metallic surface displays light-induced collective processes between two ordered mixed spin-state phases with two distinct timescale dynamics. These results open a way to molecular scale control of two-dimensional spin cross-over layers. PMID:27425776

  6. Molecular-scale dynamics of light-induced spin cross-over in a two-dimensional layer

    NASA Astrophysics Data System (ADS)

    Bairagi, Kaushik; Iasco, Olga; Bellec, Amandine; Kartsev, Alexey; Li, Dongzhe; Lagoute, Jérôme; Chacon, Cyril; Girard, Yann; Rousset, Sylvie; Miserque, Frédéric; Dappe, Yannick J.; Smogunov, Alexander; Barreteau, Cyrille; Boillot, Marie-Laure; Mallah, Talal; Repain, Vincent

    2016-07-01

    Spin cross-over molecules show the unique ability to switch between two spin states when submitted to external stimuli such as temperature, light or voltage. If controlled at the molecular scale, such switches would be of great interest for the development of genuine molecular devices in spintronics, sensing and for nanomechanics. Unfortunately, up to now, little is known on the behaviour of spin cross-over molecules organized in two dimensions and their ability to show cooperative transformation. Here we demonstrate that a combination of scanning tunnelling microscopy measurements and ab initio calculations allows discriminating unambiguously between both states by local vibrational spectroscopy. We also show that a single layer of spin cross-over molecules in contact with a metallic surface displays light-induced collective processes between two ordered mixed spin-state phases with two distinct timescale dynamics. These results open a way to molecular scale control of two-dimensional spin cross-over layers.

  7. Molecular-scale dynamics of light-induced spin cross-over in a two-dimensional layer

    PubMed Central

    Bairagi, Kaushik; Iasco, Olga; Bellec, Amandine; Kartsev, Alexey; Li, Dongzhe; Lagoute, Jérôme; Chacon, Cyril; Girard, Yann; Rousset, Sylvie; Miserque, Frédéric; Dappe, Yannick J; Smogunov, Alexander; Barreteau, Cyrille; Boillot, Marie-Laure; Mallah, Talal; Repain, Vincent

    2016-01-01

    Spin cross-over molecules show the unique ability to switch between two spin states when submitted to external stimuli such as temperature, light or voltage. If controlled at the molecular scale, such switches would be of great interest for the development of genuine molecular devices in spintronics, sensing and for nanomechanics. Unfortunately, up to now, little is known on the behaviour of spin cross-over molecules organized in two dimensions and their ability to show cooperative transformation. Here we demonstrate that a combination of scanning tunnelling microscopy measurements and ab initio calculations allows discriminating unambiguously between both states by local vibrational spectroscopy. We also show that a single layer of spin cross-over molecules in contact with a metallic surface displays light-induced collective processes between two ordered mixed spin-state phases with two distinct timescale dynamics. These results open a way to molecular scale control of two-dimensional spin cross-over layers. PMID:27425776

  8. Electronic Spin Crossover of Iron in Ferroperclase in Earth?s Lower Mantle

    SciTech Connect

    Lin, J F; Vanko, G; Jacobsen, S D; Iota, V; Struzhkin, V V; Prakapenka, V B; Kuznetsov, A; Yoo, C S

    2007-01-25

    Pressure-induced electronic spin-pairing transitions of iron and associated effects on the physical properties have been reported to occur in the lower-mantle ferropericlase, silicate perosvkite, and perhaps in post silicate perovskite at high pressures and room temperature. These recent results are motivating geophysicists and geodynamicists to reevaluate the implications of spin transitions on the seismic heterogeneity, composition, as well as the stability of the thermal upwellings of the Earth's lower mantle. Here we have measured the spin states of iron in ferropericlase and its crystal structure up to 95 GPa and 2000 K using a newly constructed X-ray emission spectroscopy and diffraction with the laser-heated diamond cell. Our results show that an isosymmetric spin crossover occurs over a pressure-temperature range extending from the upper part to the lower part of the lower mantle, and low-spin ferropericlase likely exists in the lowermost mantle. Although continuous changes in physical and chemical properties are expected to occur across the spin crossover, the spin crossover results in peculiar behavior in the thermal compression and sound velocities. Therefore, knowledge of the fraction of the spin states in the lower-mantle phases is thus essential to correctly evaluate the composition, geophysics, and dynamics of the Earth's lower mantle.

  9. Genetic regulation of meiotic cross-overs between related genomes in Brassica napus haploids and hybrids.

    PubMed

    Nicolas, Stéphane D; Leflon, Martine; Monod, Hervé; Eber, Frédérique; Coriton, Olivier; Huteau, Virginie; Chèvre, Anne-Marie; Jenczewski, Eric

    2009-02-01

    Although the genetic regulation of recombination in allopolyploid species plays a pivotal role in evolution and plant breeding, it has received little recent attention, except in wheat (Triticum aestivum). PrBn is the main locus that determines the number of nonhomologous associations during meiosis of microspore cultured Brassica napus haploids (AC; 19 chromosomes). In this study, we examined the role played by PrBn in recombination. We generated two haploid x euploid populations using two B. napus haploids with differing PrBn (and interacting genes) activity. We analyzed molecular marker transmission in these two populations to compare genetic changes, which have arisen during meiosis. We found that cross-over number in these two genotypes was significantly different but that cross-overs between nonhomologous chromosomes showed roughly the same distribution pattern. We then examined genetic recombination along a pair of A chromosomes during meiosis of B. rapa x B. napus AAC and AACC hybrids that were produced with the same two B. napus genotypes. We observed significant genotypic variation in cross-over rates between the two AAC hybrids but no difference between the two AACC hybrids. Overall, our results show that PrBn changes the rate of recombination between nonhomologous chromosomes during meiosis of B. napus haploids and also affects homologous recombination with an effect that depends on plant karyotype.

  10. Spin crossover in solid and liquid (Mg,Fe)O at extreme conditions

    NASA Astrophysics Data System (ADS)

    Stixrude, Lars; Holmstrom, Eero

    Ferropericlase, (Mg,Fe)O, is a major constituent of the Earth's lower mantle (24-136 GPa). Understanding the properties of this component is important not only in the solid state, but also in the molten state, as the planet almost certainly hosted an extensive magma ocean initially. With increasing pressure, the Fe ions in the material begin to collapse from a magnetic to a nonmagnetic spin state. This crossover affects thermodynamic, transport, and electrical properties. Using first-principles molecular dynamics simulations, thermodynamic integration, and adiabatic switching, we present a phase diagram of the spin crossover. In both solid and liquid, we find a broad pressure range of coexisting magnetic and non-magnetic ions due to the favorable enthalpy of mixing of the two. In the solid increasing temperature favors the high spin state, while in the liquid the opposite occurs, due to the higher electronic entropy of the low spin state. Because the physics of the crossover differ in solid and liquid, melting produces a large change in spin state that may affect the buoyancy of crystals freezing from the magma ocean in the earliest Earth. This research was supported by the European Research Council under Advanced Grant No. 291432 ``MoltenEarth'' (FP7/2007-2013).

  11. Knee Kinematics is Altered Post-Fatigue While Performing a Crossover Task

    PubMed Central

    Cortes, Nelson; Greska, Eric; Ambegaonkar, Jatin P.; Kollock, Roger O.; Caswell, Shane V.; Onate, James A.

    2013-01-01

    Purpose To examine the effect of a sequential fatigue protocol on lower extremity biomechanics during a crossover cutting task in female soccer players. Methods Eighteen female collegiate soccer players alternated between a fatigue protocol and two consecutive unanticipated crossover trials until fatigue was reached. Lower extremity biomechanics were evaluated during the crossover using a 3D motion capture system and two force plates. Repeated measures ANOVAs analyzed differences between three sequential stages of fatigue (pre, 50%, 100%) for each dependent variable (α=0.05). Results Knee flexion angles at initial contact (IC) for pre- (−32±9°) and 50% (−29±11°) were significantly higher than at 100% fatigue (−22±9°) (p<0.001 and p=0.015, respectively). Knee adduction angles at IC for pre- (9±5°) and 50% (8±4°) were significantly higher (p=0.006 and p=0.049, respectively) than at 100% fatigue (6±4°). Conclusions Fatigue altered sagittal and frontal knee kinematics after 50% fatigue whereupon participants had diminished knee control at initial contact. Interventions should attempt to reduce the negative effects of fatigue on lower extremity biomechanics by promotion appropriate frontal plane alignment, and increased knee flexion during fatigue status. PMID:24045915

  12. Qualitative determination of H2S crossover rates in nation membranes using ion-probe techniques

    SciTech Connect

    Brosha, Eric L; Rockward, Tommy; Uribe, Francisco A; Garzon, Fernando H

    2008-01-01

    Polymer electrolyte membrane fuel cells are sensitive to impurities that may be present in either the oxidizer or fuel. H2S, even at the ppb level, will have a dramatic and adverse affect on fuel cell performance. The H2S permeability through dry and humidified Nafion PEMFC membranes was studied using ion probe techniques. A sulfide anti-oxidant buffer solution was used to trap and concentrate trace quantities of H2S that permeated through 50 cm2samples of Nafion 117 and 212 membranes using a partial pressure difference up to I030ppm at room temperature. Experiments were conducted for up to 24 hours in order to achieve sulfide ion concentrations high enough to be precisely determined by subsequent titration with Pb(N03)2. The rate of H2S crossover for dry 117 and 212 were identical at 1.2e-7 g/min. Humidification increased the crossover rate to 5.ge-7 glmin and 1.8e-6 glmin for 117 and 212 respectively. Although the data collected in this work show that the rate of H2S crossover increases with water content and reduced membrane thickness, an accurate determination of permeation constants from this work was not possible because the H2S partial pressure was not constant throughout the experiment.

  13. Numerical Simulations of Daytime Temperature and Humidity Crossover Effects in London

    NASA Astrophysics Data System (ADS)

    Sparks, N.; Toumi, R.

    2015-01-01

    The effect of the London urban area on vertical profiles of temperature and humidity was analyzed using a mesoscale model. It was found that the near-surface warming and drying effects usually associated with the urban heat island in London in the summer daytime are reversed at heights near the top of the boundary layer. This effect has previously been observed for nighttime temperatures above cities and termed a `crossover'. The mechanism proposed here to explain this new phenomenon, the daytime crossover, is similar to the previously suggested cause of the nighttime effect, that is, increased entrainment of warm dry air into the top of a cooler, more humid, boundary layer. The median summer daytime temperature crossover was found to be 1.1 K. The cooling was shown to be of a similar magnitude to the warming near the surface and extends up to 100 km downwind with a maximum magnitude at about 1500 UTC in summer. The moistening occurred over a similar spatial scale and peak values were typically two times greater than the near-surface drying effect.

  14. Microsatellite diversity and crossover regions within homozygous and heterozygous SLA haplotypes of different pig breeds.

    PubMed

    Ando, Asako; Uenishi, Hirohide; Kawata, Hisako; Tanaka-Matsuda, Maiko; Shigenari, Atsuko; Flori, Laurence; Chardon, Patrick; Lunney, Joan K; Kulski, Jerzy K; Inoko, Hidetoshi

    2008-07-01

    Our aim was to investigate microsatellite (MS) diversity and find crossover regions at 42 polymorphic MS loci in the swine leukocyte antigen (SLA) genomic region of 72 pigs with different well-defined homozygous and heterozygous SLA haplotypes. We analyzed the genetic polymorphisms of 42 MS markers in 23 SLA homozygous-heterozygous, common pig breeds with 12 SLA serological haplotypes and 49 National Institutes of Health (NIH) and Clawn homozygous-heterozygous miniature pigs with nine SLA serological or genotyped haplotypes including four recombinant haplotypes. In comparing the same and different haplotypes, both haplospecific patterns and allelic variations were observed at the MS loci. Some of the shared haplotype blocks extended over 2 Mb suggesting the existence of strong linkage disequilibrium (LD) in the entire SLA region. Crossover regions were easily defined by the MS markers within the class I and/or III region in the NIH and Clawn recombinant haplotypes. The present haplotype comparison shows that our set of MS markers provides a fast and cost-efficient alternative, or complementary, method to the serological or sequence-based determination of the SLA alleles for the characterization of SLA haplotypes and/or the crossover regions between different haplotypes.

  15. Evolution of recombination in eutherian mammals: insights into mechanisms that affect recombination rates and crossover interference.

    PubMed

    Segura, Joana; Ferretti, Luca; Ramos-Onsins, Sebastián; Capilla, Laia; Farré, Marta; Reis, Fernanda; Oliver-Bonet, Maria; Fernández-Bellón, Hugo; Garcia, Francisca; Garcia-Caldés, Montserrat; Robinson, Terence J; Ruiz-Herrera, Aurora

    2013-11-22

    Recombination allows faithful chromosomal segregation during meiosis and contributes to the production of new heritable allelic variants that are essential for the maintenance of genetic diversity. Therefore, an appreciation of how this variation is created and maintained is of critical importance to our understanding of biodiversity and evolutionary change. Here, we analysed the recombination features from species representing the major eutherian taxonomic groups Afrotheria, Rodentia, Primates and Carnivora to better understand the dynamics of mammalian recombination. Our results suggest a phylogenetic component in recombination rates (RRs), which appears to be directional, strongly punctuated and subject to selection. Species that diversified earlier in the evolutionary tree have lower RRs than those from more derived phylogenetic branches. Furthermore, chromosome-specific recombination maps in distantly related taxa show that crossover interference is especially weak in the species with highest RRs detected thus far, the tiger. This is the first example of a mammalian species exhibiting such low levels of crossover interference, highlighting the uniqueness of this species and its relevance for the study of the mechanisms controlling crossover formation, distribution and resolution.

  16. Organic-aqueous crossover coating process for the desmopressin orally disintegrating microparticles.

    PubMed

    Kim, Ju-Young; Hwang, Kyu-Mok; Park, Chun-Woong; Rhee, Yun-Seok; Park, Eun-Seok

    2015-02-01

    The purpose of the present study was to prepare desmopressin orally disintegrating microparticles (ODMs) using organic-aqueous crossover coating process which featured an organic sub-coating followed by an aqueous active coating. Sucrose beads and hydroxypropyl cellulose (HPC) were used as inert cores and a coating material, respectively. Characterizations including size distribution analysis, in-vitro release studies and in-vitro disintegration studies were performed. A pharmacokinetic study of the ODMs was also conducted in eight beagle dogs. It was found that sucrose beads should be coated using organic solvents to preserve their original morphology. For the active coating, the aqueous coating solution should be used for drug stability. When sucrose beads were coated using organic-aqueous crossover coating process, double-layer ODMs with round shapes were produced with detectable impurities below limit of US Pharmacopeia. The median size of ODMs was 195.6 μm, which was considered small enough for a good mouthfeel. The ODMs dissolved in artificial saliva within 15 s because of hydrophilic materials including sucrose and HPC in the ODMs. Because of its fast-dissolving properties, 100% release of the drug was reached within 5 min. Pharmacokinetic parameters including Cmax and AUC24 indicated bioequivalence of the ODMs and the conventional immediate release tablets. Therefore, by using the organic-aqueous crossover coating process, double-layer ODMs were successively prepared with small size, round shapes and good drug stability. PMID:24252109

  17. The synaptonemal complex protein ZYP1 is required for imposition of meiotic crossovers in barley.

    PubMed

    Barakate, Abdellah; Higgins, James D; Vivera, Sebastian; Stephens, Jennifer; Perry, Ruth M; Ramsay, Luke; Colas, Isabelle; Oakey, Helena; Waugh, Robbie; Franklin, F Chris H; Armstrong, Susan J; Halpin, Claire

    2014-02-01

    In many cereal crops, meiotic crossovers predominantly occur toward the ends of chromosomes and 30 to 50% of genes rarely recombine. This limits the exploitation of genetic variation by plant breeding. Previous reports demonstrate that chiasma frequency can be manipulated in plants by depletion of the synaptonemal complex protein ZIPPER1 (ZYP1) but conflict as to the direction of change, with fewer chiasmata reported in Arabidopsis thaliana and more crossovers reported for rice (Oryza sativa). Here, we use RNA interference (RNAi) to reduce the amount of ZYP1 in barley (Hordeum vulgare) to only 2 to 17% of normal zygotene levels. In the ZYP1(RNAi) lines, fewer than half of the chromosome pairs formed bivalents at metaphase and many univalents were observed, leading to chromosome nondisjunction and semisterility. The number of chiasmata per cell was reduced from 14 in control plants to three to four in the ZYP1-depleted lines, although the localization of residual chiasmata was not affected. DNA double-strand break formation appeared normal, but the recombination pathway was defective at later stages. A meiotic time course revealed a 12-h delay in prophase I progression to the first labeled tetrads. Barley ZYP1 appears to function similarly to ZIP1/ZYP1 in yeast and Arabidopsis, with an opposite effect on crossover number to ZEP1 in rice, another member of the Poaceae. PMID:24563202

  18. Viscosity of liquid Ag-In-Sb-Te: Evidence of a fragile-to-strong crossover.

    PubMed

    Orava, J; Weber, H; Kaban, I; Greer, A L

    2016-05-21

    The temperature-dependent viscosity η(T) is measured for the equilibrium liquid of the chalcogenide Ag-In-Sb-Te (AIST), the first time this has been reported for a material of actual interest for phase-change memory. The measurements, in the range 829-1254 K, are made using an oscillating-crucible viscometer, and show a liquid with high fragility and low viscosity, similar to liquid pure metals. Combining the high-temperature viscosity measurements with values inferred from crystal growth rates in the supercooled liquid allows the form of η(T) to be estimated over the entire temperature range from above the melting point down to the glass transition. It is then clear that η(T) for liquid AIST cannot be described with a single fragility value, unlike other phase-change chalcogenides such as liquid Ge-Sb-Te. There is clear evidence for a fragile-to-strong crossover on cooling liquid AIST, similar to that analyzed in Te85Ge15. The change in fragility associated with the crossover in both these cases is rather weak, giving a broad temperature range over which η(T) is near-Arrhenius. We discuss how such behavior may be beneficial for the performance of phase-change memory. Consideration of the fragile-to-strong crossover in liquid chalcogenides may be important in tuning compositions to optimize the device performance. PMID:27208954

  19. Observing the 1D-3D Crossover in a Spin-Imbalanced Fermi Gas

    NASA Astrophysics Data System (ADS)

    Revelle, Melissa C.; Fry, Jacob A.; Olsen, Ben A.; Hulet, Randall G.

    2016-05-01

    Trapped two-component Fermi gases phase separate into superfluid and normal phases when their spin populations are imbalanced. In 3D, a balanced superfluid core is surrounded by shells of partially polarized and normal phases, while in 1D, the balanced superfluid occupies the low density wings. We explored the crossover from 3D to 1D using a two-spin component ultracold atomic gas of 6 Li prepared in the lowest two hyperfine sublevels, where the interactions are tuned by a Feshbach resonance. The atoms are confined to 1D tubes where the tunneling rate t between tubes is varied by changing the depth of a 2D optical lattice. We observe the transition from 1D to 3D-like phase separation by varying t and interaction strength which changes the pair binding energy ɛB. We find a universal scaling of the dimensional crossover with t /ɛB , in agreement with previous theory. The crossover region is believed to be the most promising to find the exotic FFLO superfluid phase. Supported by the NSF and the Welch Foundation.

  20. Gas-liquid phase coexistence and crossover behavior of binary ionic fluids with screened Coulomb interactions.

    PubMed

    Patsahan, O

    2014-06-01

    We study the effects of an interaction range on the gas-liquid phase diagram and the crossover behavior of a simple model of ionic fluids: an equimolar binary mixture of equisized hard spheres interacting through screened Coulomb potentials which are repulsive between particles of the same species and attractive between particles of different species. Using the collective variables theory, we find explicit expressions for the relevant coefficients of the effective φ{4} Ginzburg-Landau Hamiltonian in a one-loop approximation. Within the framework of this approximation, we calculate the critical parameters and gas-liquid phase diagrams for varying inverse screening length z. Both the critical temperature scaled by the Yukawa potential contact value and the critical density rapidly decrease with an increase of the interaction range (a decrease of z) and then for z<0.05 they slowly approach the values found for a restricted primitive model (RPM). We find that gas-liquid coexistence region reduces with an increase of z and completely vanishes at z≃2.78. Our results clearly show that an increase in the interaction range leads to a decrease of the crossover temperature. For z≃0.01, the crossover temperature is the same as for the RPM.

  1. Viscosity of liquid Ag-In-Sb-Te: Evidence of a fragile-to-strong crossover

    NASA Astrophysics Data System (ADS)

    Orava, J.; Weber, H.; Kaban, I.; Greer, A. L.

    2016-05-01

    The temperature-dependent viscosity η(T) is measured for the equilibrium liquid of the chalcogenide Ag-In-Sb-Te (AIST), the first time this has been reported for a material of actual interest for phase-change memory. The measurements, in the range 829-1254 K, are made using an oscillating-crucible viscometer, and show a liquid with high fragility and low viscosity, similar to liquid pure metals. Combining the high-temperature viscosity measurements with values inferred from crystal growth rates in the supercooled liquid allows the form of η(T) to be estimated over the entire temperature range from above the melting point down to the glass transition. It is then clear that η(T) for liquid AIST cannot be described with a single fragility value, unlike other phase-change chalcogenides such as liquid Ge-Sb-Te. There is clear evidence for a fragile-to-strong crossover on cooling liquid AIST, similar to that analyzed in Te85Ge15. The change in fragility associated with the crossover in both these cases is rather weak, giving a broad temperature range over which η(T) is near-Arrhenius. We discuss how such behavior may be beneficial for the performance of phase-change memory. Consideration of the fragile-to-strong crossover in liquid chalcogenides may be important in tuning compositions to optimize the device performance.

  2. Structural signatures evidenced in dynamic crossover phenomena in metallic glass-forming liquids

    NASA Astrophysics Data System (ADS)

    Hu, Y. C.; Li, F. X.; Li, M. Z.; Bai, H. Y.; Wang, W. H.

    2016-05-01

    Molecular dynamics simulations were performed to investigate dynamic evolution in metallic glass-forming liquids during quenching from high temperature above melting point down to supercooled region. Two crossover temperatures TA and TS (TA > TS) are identified, and their physical meanings are clarified. TA and TS are found to be not only the sign of dynamic crossover phenomena but also the manifestation of two key structure correlation lengths ξ s . As temperature decreases below TA, ξ s goes beyond the nearest-neighbor distance, resulting in the Arrhenius-to-non-Arrhenius transition of structural relaxation time and the failure of Stokes-Einstein (SE) relation. As TS is traversed, the increase rate of ξ s reaches the maximum, leading to the simultaneous appearance of dynamical heterogeneity and fractional SE relation. It is further found that structure correlation increases much faster than dynamic correlation, playing a role of structural precursor for dynamic evolution in liquids. Thus, a structural link is established for deeper understanding dynamic crossover phenomena.

  3. The black/white mortality crossover: investigation in a community-based study.

    PubMed

    Wing, S; Manton, K G; Stallard, E; Hames, C G; Tryoler, H A

    1985-01-01

    The black/white mortality crossover at about age 75, a result of lower white mortality rates at younger ages and lower black rates at the oldest ages, has been observed in U.S. vital statistics since 1900. Though a persistant observation in such data, its validity has been challenged by questions about census enumeration and age reporting on death certificates. Analyses of 20 years experience of all-cause mortality in the community-based Evans County Study using a Weibull model of age specific mortality rates showed a statistically significant black/white mortality crossover for both men (at age 73) and women (at age 85). The finding of a crossover in this longitudinally followed population is significant because the age reporting for both survivors and age at death for nonsurvivors were obtained in the study protocol and did not rely on age reporting either in census data or on the death certificate. Differences in the age and sex patterns of mortality between two populations living in the same geographic region are relevant to questions about the etiology of the major age-related chronic diseases as well as to topics of current interest in health care policy.

  4. PREFACE: Dynamic crossover phenomena in water and other glass-forming liquids Dynamic crossover phenomena in water and other glass-forming liquids

    NASA Astrophysics Data System (ADS)

    Chen, Sow-Hsin; Baglioni, Piero

    2012-02-01

    This special section has been inspired by the workshop on Dynamic Crossover Phenomena in Water and Other Glass-Forming Liquids, held during November 11-13, 2010 at Pensione Bencistà, Fiesole, Italy, a well-preserved 14th century Italian villa tucked high in the hills overlooking Florence. The meeting, an assembly of world renowned scientists, was organized as a special occasion to celebrate the 75th birthday of Professor Sow-Hsin Chen of MIT, a pioneer in several aspects of complex fluids and soft matter physics. The workshop covered a large variety of experimental and theoretical research topics of current interest related to dynamic crossover phenomena in water and, more generally, in other glass-forming liquids. The 30 invited speakers/lecturers and approximately 60 participants were a select group of prominent physicists and chemists from the USA, Europe, Asia and Mexico, who are actively working in the field. Some highlights of this special issue include the following works. Professor Yamaguchi's group and their collaborators present a neutron spin echo study of the coherent intermediate scattering function of heavy water confined in cylindrical pores of MCM-41-C10 silica material in the temperature range 190-298 K. They clearly show that a fragile-to-strong (FTS) dynamic crossover occurs at about 225 K. They attribute the FTS dynamic crossover to the formation of a tetrahedral-like structure, which is preserved in the bulk-like water confined to the central part of the cylindrical pores. Mamontov and Kolesnikov et al study the collective excitations in an aqueous solution of lithium chloride over a temperature range of 205-270 K using neutron and x-ray Rayleigh-Brillouin (coherent) scattering. They detect both the low-frequency and the high-frequency sounds known to exist in pure bulk water above the melting temperature. They also perform neutron (incoherent) and x-ray (coherent) elastic intensity scan measurements. Clear evidence of the crossover in the

  5. 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.

  6. Identification of DSB-1, a Protein Required for Initiation of Meiotic Recombination in Caenorhabditis elegans, Illuminates a Crossover Assurance Checkpoint

    PubMed Central

    Stamper, Ericca L.; Rodenbusch, Stacia E.; Rosu, Simona; Ahringer, Julie; Villeneuve, Anne M.; Dernburg, Abby F.

    2013-01-01

    Meiotic recombination, an essential aspect of sexual reproduction, is initiated by programmed DNA double-strand breaks (DSBs). DSBs are catalyzed by the widely-conserved Spo11 enzyme; however, the activity of Spo11 is regulated by additional factors that are poorly conserved through evolution. To expand our understanding of meiotic regulation, we have characterized a novel gene, dsb-1, that is specifically required for meiotic DSB formation in the nematode Caenorhabditis elegans. DSB-1 localizes to chromosomes during early meiotic prophase, coincident with the timing of DSB formation. DSB-1 also promotes normal protein levels and chromosome localization of DSB-2, a paralogous protein that plays a related role in initiating recombination. Mutations that disrupt crossover formation result in prolonged DSB-1 association with chromosomes, suggesting that nuclei may remain in a DSB-permissive state. Extended DSB-1 localization is seen even in mutants with defects in early recombination steps, including spo-11, suggesting that the absence of crossover precursors triggers the extension. Strikingly, failure to form a crossover precursor on a single chromosome pair is sufficient to extend the localization of DSB-1 on all chromosomes in the same nucleus. Based on these observations we propose a model for crossover assurance that acts through DSB-1 to maintain a DSB-permissive state until all chromosome pairs acquire crossover precursors. This work identifies a novel component of the DSB machinery in C. elegans, and sheds light on an important pathway that regulates DSB formation for crossover assurance. PMID:23990794

  7. 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

  8. Increased calcium absorption from synthetic stable amorphous calcium carbonate: double-blind randomized crossover clinical trial in postmenopausal women.

    PubMed

    Vaisman, Nachum; Shaltiel, Galit; Daniely, Michal; Meiron, Oren E; Shechter, Assaf; Abrams, Steven A; Niv, Eva; Shapira, Yami; Sagi, Amir

    2014-10-01

    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 (CCC) using the dual stable isotope technique. The study was conducted in the Unit of Clinical Nutrition, Tel Aviv Sourasky Medical Center, Israel. The study population included 15 early postmenopausal women aged 54.9 ± 2.8 (mean ± SD) years with no history of major medical illness or metabolic bone disorder, excess calcium intake, or vitamin D deficiency. Standardized breakfast was followed by randomly provided CCC or ACC capsules containing 192 mg elemental calcium labeled with 44Ca at intervals of at least 3 weeks. After swallowing the capsules, intravenous CaCl2 labeled with 42Ca on was administered on each occasion. Fractional calcium absorption (FCA) of ACC and CCC was calculated from the 24-hour urine collection following calcium administration. The results indicated that FCA of ACC was doubled (± 0.96 SD) on average compared to that of CCC (p < 0.02). The higher absorption of the synthetic stable ACC may serve as a more efficacious way of calcium supplementation.

  9. Role of mobile phones in motor vehicle crashes resulting in hospital attendance: a case-crossover study

    PubMed Central

    McEvoy, Suzanne P; Stevenson, Mark R; McCartt, Anne T; Woodward, Mark; Haworth, Claire; Palamara, Peter; Cercarelli, Rina

    2005-01-01

    Objectives To explore the effect of drivers' use of mobile (cell) phones on road safety. Design A case-crossover study. Setting Perth, Western Australia. Participants 456 drivers aged ≥ 17 years who owned or used mobile phones and had been involved in road crashes necessitating hospital attendance between April 2002 and July 2004. Main outcome measure Driver's use of mobile phone at estimated time of crash and on trips at the same time of day in the week before the crash. Interviews with drivers in hospital and phone company's records of phone use. Results Driver's use of a mobile phone up to 10 minutes before a crash was associated with a fourfold increased likelihood of crashing (odds ratio 4.1, 95% confidence interval 2.2 to 7.7, P < 0.001). Risk was raised irrespective of whether or not a hands-free device was used (hands-free: 3.8, 1.8 to 8.0, P < 0.001; hand held: 4.9, 1.6 to 15.5, P = 0.003). Increased risk was similar in men and women and in drivers aged ≥ 30 and < 30 years. A third (n = 21) of calls before crashes and on trips during the previous week were reportedly on hand held phones. Conclusions When drivers use a mobile phone there is an increased likelihood of a crash resulting in injury. Using a hands-free phone is not any safer. PMID:16012176

  10. Safety and efficacy of vardenafil versus sertraline in the treatment of premature ejaculation: a randomised, prospective and crossover study.

    PubMed

    Mathers, M J; Klotz, T; Roth, S; Lümmen, G; Sommer, F

    2009-06-01

    We investigated safety and efficacy of vardenafil and sertraline in premature ejaculation (PE). Seventy-two men graded their primary PE on a scale of 0-8 (0 = almost never, 8 = almost always). Intravaginal ejaculatory latency time (IELT) was measured. Patients were included if they scored their PE as 4 or greater and their IELTs were less than 1.30 min. After 6 weeks of behavioural psychosexual therapy, 49 patients still had a PE of 4 or greater and an IELT less than 1.30 min and they were randomised: 6 weeks vardenafil (10 mg) or sertraline (50 mg). After a wash-out phase for 1 week, medication was changed in a cross-over design. Initially, all 72 men with PE received behavioural therapy. Twenty-three men were satisfied with treatment and excluded. The remaining 49 men graded their PE as 5.94 +/- 1.6 and IELT was 0.59 min and patients were randomised. Four men discontinued the study. Vardenafil improved PE grading: 2.7 +/- 2.1 (P < 0.01) and IELT increased to 5.01 +/- 3.69 (P < 0.001). PE grading improved 1.92 +/- 1.32, (P < 0.01) and IELT 3.12 +/- 1.89 (P < 0.001) with sertraline. It is concluded that vardenafil and sertraline are useful agents in the pharmacological treatment of PE.

  11. Effect on lipoprotein profile of replacing butter with margarine in a low fat diet: randomised crossover study with hypercholesterolaemic subjects.

    PubMed Central

    Chisholm, A.; Mann, J.; Sutherland, W.; Duncan, A.; Skeaff, M.; Frampton, C.

    1996-01-01

    OBJECTIVE--To examine the effect on lipid and lipoprotein concentrations when butter or an unsaturated margarine is used for cooking or spreading in a reduced fat diet. DESIGN--Randomised crossover study with two intervention periods of six weeks' duration separated by a five week washout. SETTING--Community setting in New Zealand. SUBJECTS--49 volunteers with polygenic hypercholesterolaemia and baseline total cholesterol concentration in the range 5.5-7.9 mmol/l. MAIN OUTCOME MEASURES--Concentrations of total and low density lipoprotein, Lp(a) lipoprotein, high density lipoprotein, apolipoprotein B 100, and apolipoprotein A I. RESULTS--Concentrations of low density lipoprotein cholesterol and apolipoprotein B were about 10% lower with margarine than with butter. Lp(a) lipoprotein and high density lipoprotein cholesterol concentrations were similar with the two diets. CONCLUSION--Despite concerns about adverse effects on lipoproteins of trans fatty acids in margarines, the use of unsaturated margarine rather than butter by hypercholesterolaemic people is associated with a lipoprotein profile that would be expected to reduce cardiovascular risk. PMID:8616303

  12. Salivary Oxytocin Concentrations in Males following Intranasal Administration of Oxytocin: A Double-Blind, Cross-Over Study.

    PubMed

    Daughters, Katie; Manstead, Antony S R; Hubble, Kelly; Rees, Aled; Thapar, Anita; van Goozen, Stephanie H M

    2015-01-01

    The use of intranasal oxytocin (OT) in research has become increasingly important over the past decade. Although researchers have acknowledged a need for further investigation of the physiological effects of intranasal administration, few studies have actually done so. In the present double-blind cross-over study we investigated the longevity of a single 24 IU dose of intranasal OT measured in saliva in 40 healthy adult males. Salivary OT concentrations were significantly higher in the OT condition, compared to placebo. This significant difference lasted until the end of testing, approximately 108 minutes after administration, and peaked at 30 minutes. Results showed significant individual differences in response to intranasal OT administration. To our knowledge this is the largest and first all-male within-subjects design study to demonstrate the impact of intranasal OT on salivary OT concentrations. The results are consistent with previous research in suggesting that salivary OT is a valid matrix for OT measurement. The results also suggest that the post-administration 'wait-time' prior to starting experimental tasks could be reduced to 30 minutes, from the 45 minutes typically used, thereby enabling testing during peak OT concentrations. Further research is needed to ascertain whether OT concentrations after intranasal administration follow similar patterns in females, and different age groups. PMID:26669935

  13. Fiber content of diet affects exhaled breath volatiles in fasting and postprandial state in a pilot crossover study.

    PubMed

    Raninen, Kaisa J; Lappi, Jenni E; Mukkala, Maria L; Tuomainen, Tomi-Pekka; Mykkänen, Hannu M; Poutanen, Kaisa S; Raatikainen, Olavi J

    2016-06-01

    Our pilot study examined the potential of exhaled breath analysis in studying the metabolic effects of dietary fiber (DF). We hypothesized that a high-fiber diet (HFD) containing whole grain rye changes volatile organic compound (VOC) levels in exhaled breath and that consuming a single meal affects these levels. Seven healthy men followed a week-long low-fiber diet (17 g/d) and HFD (44 g/d) in a randomized crossover design. A test meal containing 50 g of the available carbohydrates from wheat bread was served as breakfast after each week. Alveolar exhaled breath samples were analyzed at fasting state and 30, 60, and 120 minutes after this meal parallel to plasma glucose, insulin, and serum lipids. We used solid-phase microextraction and gas chromatography-mass spectrometry for detecting changes in 15 VOCs. These VOCs were acetone, ethanol, 1-propanol, 2-propanol, 1-butanol, acetic acid, propionic acid, butyric acid, valeric acid, isovaleric acid, 2-methylbutyric acid, hexanoic acid, acetoin, diacetyl, and phenol. Exhaled breath 2-methylbutyric acid in the fasting state and 1-propanol at 120 minutes decreased (P = .091 for both) after an HFD. Ingestion of the test meal increased ethanol, 1-propanol, acetoin, propionic acid, and butyric acid levels while reducing acetone, 1-butanol, diacetyl, and phenol levels. Both DF diet content and having a single meal affected breathVOCs. Exploring exhaled breath further could help to develop tools for monitoring the metabolic effects of DF. PMID:27188907

  14. Effect of long-term treatment with salmeterol on asthma control: a double blind, randomised crossover study.

    PubMed Central

    Wilding, P.; Clark, M.; Thompson Coon, J.; Lewis, S.; Rushton, L.; Bennett, J.; Oborne, J.; Cooper, S.; Tattersfield, A. E.

    1997-01-01

    OBJECTIVES: To determine the effect of adding salmeterol 50 micrograms twice daily for six months to current treatment in subjects with asthma who control their inhaled corticosteroid dose according to a management plan. DESIGN: A double blind, randomised crossover study. SETTING: Nottingham. SUBJECTS: 101 subjects with mild or moderate asthma taking at least 200 micrograms twice daily of beclomethasone dipropionate or budesonide. INTERVENTIONS: Salmeterol 50 micrograms twice daily and placebo for six months each, with a one month washout. Subjects adjusted inhaled steroid dose according to guidelines. MAIN OUTCOME MEASURE: Reduction in inhaled steroid use, exacerbations of asthma, and use of oral steroids. RESULTS: Data were available for 87 subjects. When compared with placebo salmeterol treatment was associated with a 17% reduction in inhaled steroid use (95% confidence interval 12% to 22%) with no significant difference in the number of subjects who had an exacerbation (placebo 25%, salmeterol 16%) or use of oral steroids. For secondary end points salmeterol treatment was associated with higher morning and evening peak expiratory flow and forced expiratory volume in one second; a reduction in symptoms, bronchodilator use and airway responsiveness to methacholine; and no effect on serum potassium concentration, 24 hour heart rate, or the final forced expiratory volume in one second achieved during a salbutamol dose-response study. CONCLUSIONS: In subjects who adjusted their inhaled steroid treatment according to guidelines the addition of salmeterol 50 micrograms twice daily was associated with a reduction in inhaled steroid use and improved lung function and symptom control. PMID:9167559

  15. Safety and efficacy of vardenafil versus sertraline in the treatment of premature ejaculation: a randomised, prospective and crossover study.

    PubMed

    Mathers, M J; Klotz, T; Roth, S; Lümmen, G; Sommer, F

    2009-06-01

    We investigated safety and efficacy of vardenafil and sertraline in premature ejaculation (PE). Seventy-two men graded their primary PE on a scale of 0-8 (0 = almost never, 8 = almost always). Intravaginal ejaculatory latency time (IELT) was measured. Patients were included if they scored their PE as 4 or greater and their IELTs were less than 1.30 min. After 6 weeks of behavioural psychosexual therapy, 49 patients still had a PE of 4 or greater and an IELT less than 1.30 min and they were randomised: 6 weeks vardenafil (10 mg) or sertraline (50 mg). After a wash-out phase for 1 week, medication was changed in a cross-over design. Initially, all 72 men with PE received behavioural therapy. Twenty-three men were satisfied with treatment and excluded. The remaining 49 men graded their PE as 5.94 +/- 1.6 and IELT was 0.59 min and patients were randomised. Four men discontinued the study. Vardenafil improved PE grading: 2.7 +/- 2.1 (P < 0.01) and IELT increased to 5.01 +/- 3.69 (P < 0.001). PE grading improved 1.92 +/- 1.32, (P < 0.01) and IELT 3.12 +/- 1.89 (P < 0.001) with sertraline. It is concluded that vardenafil and sertraline are useful agents in the pharmacological treatment of PE. PMID:19400851

  16. Salivary Oxytocin Concentrations in Males following Intranasal Administration of Oxytocin: A Double-Blind, Cross-Over Study

    PubMed Central

    Daughters, Katie; Manstead, Antony S. R.; Hubble, Kelly; Rees, Aled; Thapar, Anita; van Goozen, Stephanie H. M.

    2015-01-01

    The use of intranasal oxytocin (OT) in research has become increasingly important over the past decade. Although researchers have acknowledged a need for further investigation of the physiological effects of intranasal administration, few studies have actually done so. In the present double-blind cross-over study we investigated the longevity of a single 24 IU dose of intranasal OT measured in saliva in 40 healthy adult males. Salivary OT concentrations were significantly higher in the OT condition, compared to placebo. This significant difference lasted until the end of testing, approximately 108 minutes after administration, and peaked at 30 minutes. Results showed significant individual differences in response to intranasal OT administration. To our knowledge this is the largest and first all-male within-subjects design study to demonstrate the impact of intranasal OT on salivary OT concentrations. The results are consistent with previous research in suggesting that salivary OT is a valid matrix for OT measurement. The results also suggest that the post-administration ‘wait-time’ prior to starting experimental tasks could be reduced to 30 minutes, from the 45 minutes typically used, thereby enabling testing during peak OT concentrations. Further research is needed to ascertain whether OT concentrations after intranasal administration follow similar patterns in females, and different age groups. PMID:26669935

  17. Kinesio Taping Does Not Alter Quadriceps Isokinetic Strength and Power in Healthy Nonathletic Men: A Prospective Crossover Study

    PubMed Central

    Korman, Paweł; Straburzyńska-Lupa, Anna; Rutkowski, Radosław; Gruszczyński, Jakub; Lewandowski, Jacek; Straburzyński-Lupa, Marcin; Łochyński, Dawid

    2015-01-01

    Objectives. The effects of Kinesio Taping (KT) on muscular performance remain largely unclear. This study aimed to investigate the acute effects of KT on the maximum concentric and eccentric quadriceps isokinetic strength. Study Design. This is a single-blinded, placebo crossover, repeated measures study. Methods. Maximum isokinetic concentric/eccentric extension torque, work, and power were assessed by an isokinetic dynamometer without taping (NT) and with KT or placebo taping (PT) in 17 healthy young men. Repeated measures one-way analysis of variance (ANOVA) was used for statistical analyses. Results. Testing concentric contractions at 60°/s or 180°/s isokinetic speed, no significant differences in peak torque (Nm), total work (J), or mean power (W) were noted among the application modes under different conditions. Testing eccentric contractions at 30°/s or 60°/s isokinetic speed, no significant differences in mentioned parameters were noted, respectively. KT on the quadriceps neither decreased nor increased muscle strength in the participants. Conclusion. KT application onto the skin overlying the quadriceps muscle does not enhance the strength or power of knee extensors in healthy men. PMID:26819953

  18. Bupivacaine 0.5 % versus articaine 4 % for the removal of lower third molars. A crossover randomized controlled trial

    PubMed Central

    Sancho-Puchades, Manuel; Vílchez-Pérez, Miguel A.; Paredes-García, Jordi; Berini-Aytés, Leonardo; Gay-Escoda, Cosme

    2012-01-01

    Objective: To compare the anesthetic action of 0.5% bupivacaine in relation to 4% articaine, both with 1:200,000 epinephrine, in the surgical removal of lower third molars. As a secondary objective hemodynamic changes using both anesthetics were analyzed. Study Design: Triple-blind crossover randomized clinical trial. Eighteen patients underwent bilateral removal of impacted lower third molars using 0.5% bupivacaine or 4% articaine in two different appointments. Preoperative, intraoperative and postoperative variables were recorded. Differences were assessed with McNemar tests and repeated measures ANOVA tests. Results: Both solutions exhibited similar latency times and intraoperative efficacy. Statistical significant lower pain levels were observed with bupivacaine between the fifth (p=0.011) and the ninth (p=0.007) postoperative hours. Bupivacaine provided significantly longer lasting soft tissue anesthesia (p<0.05). Systolic blood pressure and heart rate values were significantly higher with articaine. Conclusions: Bupivacaine could be a valid alternative to articaine especially due to its early postoperative pain prevention ability. Key words:Bupivacaine, articaine, third molar, anesthesia, postoperative pain. PMID:22143739

  19. The effect of aromatherapy abdominal massage on alleviating menstrual pain in nursing students: a prospective randomized cross-over study.

    PubMed

    Marzouk, Tyseer M F; El-Nemer, Amina M R; Baraka, Hany N

    2013-01-01

    Dysmenorrhea is a common cause of sickness absenteeism from both classes and work. This study investigated the effect of aromatherapy massage on a group of nursing students who are suffering of primary dysmenorrhea. A randomized blind clinical trial of crossover design was used. In the first treatment phase, group 1 (n = 48) received aromatherapy abdominal massage once daily for seven days prior to menstruation using the essential oils (cinnamon, clove, rose, and lavender in a base of almond oil). Group 2 (n = 47) received the same intervention but with placebo oil (almond oil). In the second treatment phase, the two groups switched to alternate regimen. Level and duration of pain and the amount of menstrual bleeding were evaluated at the baseline and after each treatment phase. During both treatment phases, the level and duration of menstrual pain and the amount of menstrual bleeding were significantly lower in the aromatherapy group than in the placebo group. These results suggests that aromatherapy is effective in alleviating menstrual pain, its duration and excessive menstrual bleeding. Aromatherapy can be provided as a nonpharmacological pain relief measure and as a part of nursing care given to girls suffering of dysmenorrhea, or excessive menstrual bleeding.

  20. PREFACE: Dynamic crossover phenomena in water and other glass-forming liquids Dynamic crossover phenomena in water and other glass-forming liquids

    NASA Astrophysics Data System (ADS)

    Chen, Sow-Hsin; Baglioni, Piero

    2012-02-01

    This special section has been inspired by the workshop on Dynamic Crossover Phenomena in Water and Other Glass-Forming Liquids, held during November 11-13, 2010 at Pensione Bencistà, Fiesole, Italy, a well-preserved 14th century Italian villa tucked high in the hills overlooking Florence. The meeting, an assembly of world renowned scientists, was organized as a special occasion to celebrate the 75th birthday of Professor Sow-Hsin Chen of MIT, a pioneer in several aspects of complex fluids and soft matter physics. The workshop covered a large variety of experimental and theoretical research topics of current interest related to dynamic crossover phenomena in water and, more generally, in other glass-forming liquids. The 30 invited speakers/lecturers and approximately 60 participants were a select group of prominent physicists and chemists from the USA, Europe, Asia and Mexico, who are actively working in the field. Some highlights of this special issue include the following works. Professor Yamaguchi's group and their collaborators present a neutron spin echo study of the coherent intermediate scattering function of heavy water confined in cylindrical pores of MCM-41-C10 silica material in the temperature range 190-298 K. They clearly show that a fragile-to-strong (FTS) dynamic crossover occurs at about 225 K. They attribute the FTS dynamic crossover to the formation of a tetrahedral-like structure, which is preserved in the bulk-like water confined to the central part of the cylindrical pores. Mamontov and Kolesnikov et al study the collective excitations in an aqueous solution of lithium chloride over a temperature range of 205-270 K using neutron and x-ray Rayleigh-Brillouin (coherent) scattering. They detect both the low-frequency and the high-frequency sounds known to exist in pure bulk water above the melting temperature. They also perform neutron (incoherent) and x-ray (coherent) elastic intensity scan measurements. Clear evidence of the crossover in the

  1. Model-Based Assessment of Alternative Study Designs in Pediatric Trials. Part I: Frequentist Approaches.

    PubMed

    Smania, G; Baiardi, P; Ceci, A; Magni, P; Cella, M

    2016-06-01

    Alternative designs can increase the feasibility of pediatric trials when compared to classical parallel designs (PaD). In this work we present a model-based approach based on clinical trial simulations for the comparison of PaD with the alternative sequential, crossover, and randomized withdrawal (RWD) designs. Study designs were evaluated in terms of: type I and II errors, sample size per arm (SS), trial duration (TD), treatment exposures, and parameter estimate precision (EP). The crossover requires the lowest SS and TD, although it implies higher placebo and no treatment exposures. RWD maximizes exposure to active treatment while minimizing that to placebo, but requires the largest SS. SS of sequential designs can sometimes be smaller than the crossover one, although with poorer EP. This pharmacometric framework allows a multiscale comparison of alternative study designs that can be used for design selection in future pediatric trials. PMID:27300083

  2. Dynamics of rye chromosome 1R regions with high or low crossover frequency in homology search and synapsis development.

    PubMed

    Valenzuela, Nohelia T; Perera, Esther; Naranjo, Tomás

    2012-01-01

    In many organisms, homologous pairing and synapsis depend on the meiotic recombination machinery that repairs double-strand DNA breaks (DSBs) produced at the onset of meiosis. The culmination of recombination via crossover gives rise to chiasmata, which locate distally in many plant species such as rye, Secale cereale. Although, synapsis initiates close to the chromosome ends, a direct effect of regions with high crossover frequency on partner identification and synapsis initiation has not been demonstrated. Here, we analyze the dynamics of distal and proximal regions of a rye chromosome introgressed into wheat to define their role on meiotic homology search and synapsis. We have used lines with a pair of two-armed chromosome 1R of rye, or a pair of telocentrics of its long arm (1RL), which were homozygous for the standard 1RL structure, homozygous for an inversion of 1RL that changes chiasma location from distal to proximal, or heterozygous for the inversion. Physical mapping of recombination produced in the ditelocentric heterozygote (1RL/1RL(inv)) showed that 70% of crossovers in the arm were confined to a terminal segment representing 10% of the 1RL length. The dynamics of the arms 1RL and 1RL(inv) during zygotene demonstrates that crossover-rich regions are more active in recognizing the homologous partner and developing synapsis than crossover-poor regions. When the crossover-rich regions are positioned in the vicinity of chromosome ends, their association is facilitated by telomere clustering; when they are positioned centrally in one of the two-armed chromosomes and distally in the homolog, their association is probably derived from chromosome elongation. On the other hand, chromosome movements that disassemble the bouquet may facilitate chromosome pairing correction by dissolution of improper chromosome associations. Taken together, these data support that repair of DSBs via crossover is essential in both the search of the homologous partner and

  3. An adaptive differential evolution algorithm with novel mutation and crossover strategies for global numerical optimization.

    PubMed

    Islam, Sk Minhazul; Das, Swagatam; Ghosh, Saurav; Roy, Subhrajit; Suganthan, Ponnuthurai Nagaratnam

    2012-04-01

    Differential evolution (DE) is one of the most powerful stochastic real parameter optimizers of current interest. In this paper, we propose a new mutation strategy, a fitness-induced parent selection scheme for the binomial crossover of DE, and a simple but effective scheme of adapting two of its most important control parameters with an objective of achieving improved performance. The new mutation operator, which we call DE/current-to-gr_best/1, is a variant of the classical DE/current-to-best/1 scheme. It uses the best of a group (whose size is q% of the population size) of randomly selected solutions from current generation to perturb the parent (target) vector, unlike DE/current-to-best/1 that always picks the best vector of the entire population to perturb the target vector. In our modified framework of recombination, a biased parent selection scheme has been incorporated by letting each mutant undergo the usual binomial crossover with one of the p top-ranked individuals from the current population and not with the target vector with the same index as used in all variants of DE. A DE variant obtained by integrating the proposed mutation, crossover, and parameter adaptation strategies with the classical DE framework (developed in 1995) is compared with two classical and four state-of-the-art adaptive DE variants over 25 standard numerical benchmarks taken from the IEEE Congress on Evolutionary Computation 2005 competition and special session on real parameter optimization. Our comparative study indicates that the proposed schemes improve the performance of DE by a large magnitude such that it becomes capable of enjoying statistical superiority over the state-of-the-art DE variants for a wide variety of test problems. Finally, we experimentally demonstrate that, if one or more of our proposed strategies are integrated with existing powerful DE variants such as jDE and JADE, their performances can also be enhanced.

  4. Synthesis of spin-crossover nano- and micro-objects in homogeneous media.

    PubMed

    Gural'skiy, Il'ya A; Quintero, Carlos M; Molnár, Gábor; Fritsky, Igor O; Salmon, Lionel; Bousseksou, Azzedine

    2012-08-01

    New methods are proposed for the synthesis of spin-crossover nano- and micro-objects. Several nano-objects that are based upon the spin-crossover complex [Fe(hptrz)(3)](OTs)(2) (hptrz=4-heptyl-1,2,4-triazole, Ts=para-toluenesulfonyl) were prepared in homogeneous media. The use of various reagents (Triton X-100, PVP, TOPO, and PEGs of different molecular weights) as stabilizing agents yielded materials of different size (6 nm-2 μm) and morphology (nanorods, nanoplates, small spherical particles, and nano- and micro-crystals). In particular, when Triton X-100 was used, a variation in the morphology from nanorods to nanoplates was observed by changing the nature of the solvent. Interestingly, the preparation of the nanorods and nanoplates was always accompanied by the formation of small spherical particles. Alternatively, when PEG was used, 200-400 nm crystals of the complex were obtained. In addition, a very promising polymer-free synthetic method is discussed that was based on the preparation of relatively stable Fe(II)-triazole oligomers in CHCl(3). Their specific treatment led to micro-crystals, small nanoparticles, or gels. The size and morphology of all of these objects were characterized by TEM and by dynamic light scattering (DLS) where possible. Their spin-crossover behavior was studied by optical and magnetic measurements. The spin-transition features for large particles (>100 nm) were very similar to that of the bulk material, that is, close to room temperature with a hysteresis width of up to 8 K. The effects of the matrix and/or size-reduction led to modification of the transition temperature and an abruptness of the spin transition for oligomeric solutions and small nanoparticles of 6 nm in size.

  5. Compressibility of water in magma and the prediction of density crossovers in mantle differentiation.

    PubMed

    Agee, Carl B

    2008-11-28

    Hydrous silicate melts appear to have greater compressibility relative to anhydrous melts of the same composition at low pressures (<2GPa); however, at higher pressures, this difference is greatly reduced and becomes very small at pressures above 5GPa. This implies that the pressure effect on the partial molar volume of water in silicate melt ( partial differentialV-H2O/ partial differentialP) is highly dependent on pressure regime. Thus, H2O can be thought of as the most compressible 'liquid oxide' component in silicate melt at low pressure, but at high pressure its compressibility resembles that of other liquid oxide components. A best-fit curve to the data on V-H2O from various studies allows calculation of hydrous melt compression curves relevant to high-pressure planetary differentiation. From these compression curves, crystal-liquid density crossovers are predicted for the mantles of the Earth and Mars. For the Earth, trapped dense hydrous melts may reside atop the 410km discontinuity, and, although not required to be hydrous, atop the core-mantle boundary (CMB), in accord with seismic observations of low-velocity zones in these regions. For Mars, a density crossover at the base of the upper mantle is predicted, which would produce a low-velocity zone at a depth of approximately 1200km. If perovskite is stable at the base of the Martian mantle, then density crossovers or trapped dense hydrous melts are unlikely to reside there, and long-lived, melt-induced, low-velocity regions atop the CMB are not predicted. PMID:18826929

  6. Quantum fluctuations in the BCS-BEC crossover of two-dimensional Fermi gases

    DOE PAGES

    He, Lianyi; Lu, Haifeng; Cao, Gaoqing; Hu, Hui; Liu, Xia -Ji

    2015-08-14

    We present a theoretical study of the ground state of the BCS-BEC crossover in dilute two-dimensional Fermi gases. While the mean-field theory provides a simple and analytical equation of state, the pressure is equal to that of a noninteracting Fermi gas in the entire BCS-BEC crossover, which is not consistent with the features of a weakly interacting Bose condensate in the BEC limit and a weakly interacting Fermi liquid in the BCS limit. The inadequacy of the two-dimensional mean-field theory indicates that the quantum fluctuations are much more pronounced than those in three dimensions. In this work, we show thatmore » the inclusion of the Gaussian quantum fluctuations naturally recovers the above features in both the BEC and the BCS limits. In the BEC limit, the missing logarithmic dependence on the boson chemical potential is recovered by the quantum fluctuations. Near the quantum phase transition from the vacuum to the BEC phase, we compare our equation of state with the known grand canonical equation of state of two-dimensional Bose gases and determine the ratio of the composite boson scattering length aB to the fermion scattering length a2D. We find aB ≃ 0.56a2D, in good agreement with the exact four-body calculation. As a result, we compare our equation of state in the BCS-BEC crossover with recent results from the quantum Monte Carlo simulations and the experimental measurements and find good agreements.« less

  7. Quantum fluctuations in the BCS-BEC crossover of two-dimensional Fermi gases

    SciTech Connect

    He, Lianyi; Lu, Haifeng; Cao, Gaoqing; Hu, Hui; Liu, Xia -Ji

    2015-08-14

    We present a theoretical study of the ground state of the BCS-BEC crossover in dilute two-dimensional Fermi gases. While the mean-field theory provides a simple and analytical equation of state, the pressure is equal to that of a noninteracting Fermi gas in the entire BCS-BEC crossover, which is not consistent with the features of a weakly interacting Bose condensate in the BEC limit and a weakly interacting Fermi liquid in the BCS limit. The inadequacy of the two-dimensional mean-field theory indicates that the quantum fluctuations are much more pronounced than those in three dimensions. In this work, we show that the inclusion of the Gaussian quantum fluctuations naturally recovers the above features in both the BEC and the BCS limits. In the BEC limit, the missing logarithmic dependence on the boson chemical potential is recovered by the quantum fluctuations. Near the quantum phase transition from the vacuum to the BEC phase, we compare our equation of state with the known grand canonical equation of state of two-dimensional Bose gases and determine the ratio of the composite boson scattering length aB to the fermion scattering length a2D. We find aB ≃ 0.56a2D, in good agreement with the exact four-body calculation. As a result, we compare our equation of state in the BCS-BEC crossover with recent results from the quantum Monte Carlo simulations and the experimental measurements and find good agreements.

  8. BCS-BEC crossover induced by a synthetic non-Abelian gauge field

    NASA Astrophysics Data System (ADS)

    Vyasanakere, Jayantha P.; Zhang, Shizhong; Shenoy, Vijay B.

    2011-07-01

    We investigate the ground state of interacting spin-(1)/(2) fermions in three dimensions at a finite density (ρ˜kF3) in the presence of a uniform non-Abelian gauge field. The gauge-field configuration (GFC) described by a vector λ≡(λx,λy,λz), whose magnitude λ determines the gauge coupling strength, generates a generalized Rashba spin-orbit interaction. For a weak attractive interaction in the singlet channel described by a small negative scattering length (kF|as|≲1), the ground state in the absence of the gauge field (λ=0) is a BCS (Bardeen-Cooper-Schrieffer) superfluid with large overlapping pairs. With increasing gauge-coupling strength, a non-Abelian gauge field engenders a crossover of this BCS ground state to a BEC (Bose-Einstein condensate) of bosons even with a weak attractive interaction that fails to produce a two-body bound state in free vacuum (λ=0). For large gauge couplings (λ/kF≫1), the BEC attained is a condensate of bosons whose properties are solely determined by the Rashba gauge field (and not by the scattering length so long as it is nonzero)—we call these bosons “rashbons.” In the absence of interactions (as=0-), the shape of the Fermi surface of the system undergoes a topological transition at a critical gauge coupling λT. For high-symmetry GFCs we show that the crossover from the BCS superfluid to the rashbon BEC occurs in the regime of λ near λT. In the context of cold atomic systems, these results make an interesting suggestion of obtaining BCS-BEC crossover through a route other than tuning the interaction between the fermions.

  9. Potentially disruptive life events: what are the immediate impacts on chronic disease management? A case-crossover analysis

    PubMed Central

    Gagne, Joshua J; Song, Zirui; Brill, Gregory; Choudhry, Niteesh K

    2016-01-01

    Objective 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. Design Observational self-controlled case-crossover design. Setting Individuals in a nationally representative US commercial health insurance database. Participants Adult individuals who initiated an oral hypoglycaemic, antihypertensive and/or statin and subsequently stopped the medication for ≥90 days. Main outcome measure 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. Results 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. Conclusions 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

  10. A Novel Magnetic Stimulator Increases Experimental Pain Tolerance in Healthy Volunteers - A Double-Blind Sham-Controlled Crossover Study

    PubMed Central

    Kortekaas, Rudie; Konopka, Karl-Heinz; Harbers, Marten; van der Hoeven, Johannes H.; van Wijhe, Marten; Aleman, André; Maurits, Natasha M.

    2013-01-01

    The ‘complex neural pulse’TM (CNP) is a neuromodulation protocol employing weak pulsed electromagnetic fields (PEMF). A pioneering paper reported an analgesic effect in healthy humans after 30 minutes of CNP-stimulation using three nested whole head coils. We aimed to devise and validate a stimulator with a novel design entailing a multitude of small coils at known anatomical positions on a head cap, to improve applicability. The main hypothesis was that CNP delivery with this novel device would also increase heat pain thresholds. Twenty healthy volunteers were enrolled in this double-blind, sham-controlled, crossover study. Thirty minutes of PEMF (CNP) or sham was applied to the head. After one week the other treatment was given. Before and after each treatment, primary and secondary outcomes were measured. Primary outcome was heat pain threshold (HPT) measured with thermal quantitative sensory testing. Other outcomes were warmth detection threshold, and aspects of cognition, emotion and motor performance. As hypothesized heat pain threshold was significantly increased after the PEMF stimulation. All other outcomes were unaltered by the PEMF but there was a trend level reduction of cognitive performance after PEMF stimulation as measured by the digit-symbol substitution task. Results from this pilot study suggest that our device is able to stimulate the brain and to modulate its function. This is in agreement with previous studies that used similar magnetic field strengths to stimulate the brain. Specifically, pain control may be achieved with PEMF and for this analgesic effect, coil design does not appear to play a dominant role. In addition, the flexible configuration with small coils on a head cap improves clinical applicability. Trial Registration Dutch Cochrane Centre NTR1093 PMID:23620795

  11. 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.

  12. A randomized, crossover, placebo-controlled clinical trial to assess the sensitivity of the CRCDS Mini-Sim to the next-day residual effects of zopiclone

    PubMed Central

    Gargano, Cynthia; Cha, Jang-Ho; Drexel, Melissa; Bautmans, An; Heirman, Ingeborg; Laethem, Tine; Hochadel, Thomas; Gheyle, Lien; Bleys, Kim; Beals, Chan; Stoch, Aubrey; Kay, Gary G.; Struyk, Arie

    2015-01-01

    Objectives: We sought to validate Cognitive Research Corporation’s Driving Simulator (CRCDS Mini-Sim) for studies of drug safety with respect to driving ability. Methods: A total of 30 healthy subjects were randomized to receive placebo or 7.5 mg zopiclone, a hypnotic known to impair driving, in random order during the 2 treatment periods of a 2 period crossover design. Results: Evening administration of 7.5 mg zopiclone increased next-day standard deviation of lateral lane position (SDLP) by 2.62 cm on average compared with evening administration of placebo, and caused significant effects on symmetry analysis. The magnitude of the change in SDLP is highly similar to changes previously observed using on-the-road driving methods. Conclusions: Further validation of the CRCDS Mini-Sim is warranted to develop this platform for drug safety studies. PMID:26240742

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

    SciTech Connect

    Mendell, M.J.; Fisk, W.J.; Petersen, M.; Hines, C.J.; Faulkner, D.; Deddens, J.A.; Dong, M.X.; Ruder, A.M.; Sullivan, D.; Boenigner, M.F.

    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 an 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.

  14. 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. PMID:27585724

  15. Crossover scaling of wavelength selection in directional solidification of binary alloys.

    PubMed

    Greenwood, Michael; Haataja, Mikko; Provatas, And Nikolas

    2004-12-10

    We simulate cellular and dendritic growth in directional solidification in dilute binary alloys using a phase-field model solved with adaptive-mesh refinement. The spacing of primary branches is examined for a wide range of thermal gradients and alloy compositions and is found to undergo a maximum as a function of pulling velocity, in agreement with experimental observations. We demonstrate that wavelength selection is unambiguously described by a nontrivial crossover scaling function from the emergence of cellular growth to the onset of dendritic fingers. This result is further validated using published experimental data, which obeys the same scaling function.

  16. Pion and η -meson mass splitting at the two-flavor chiral crossover

    NASA Astrophysics Data System (ADS)

    Heller, Markus; Mitter, Mario

    2016-10-01

    We study the splitting in the screening mass of pions and the η -meson across the chiral crossover. This splitting is determined by the 't Hooft determinant. We use results for the renormalization group scale dependence of the 't Hooft determinant obtained within the functional renormalization group in quenched QCD with two flavors. The scale dependence of the 't Hooft determinant is mapped to its temperature dependence with the help of a Polyakov-quark-meson model. As a result we obtain the temperature dependence of the splitting in the screening mass of pions and the η -meson.

  17. Measured comparison of contrast and crossover periods for passive millimeter-wave polarimetric imagery.

    PubMed

    Wilson, John P; Schuetz, Christopher A; Harrity, Charles E; Kozacik, Stephen; Eng, David L K; Prather, Dennis W

    2013-05-20

    Several targets are set-up outside and imaged by a passive millimeter-wave sensor over a 24 hour period. The sensor is capable of measuring two linear polarization states simultaneously and the contrasts of the targets are compared for the different polarizations. The choice of polarization is shown to have an impact on the contrast of different targets throughout the day. In an extreme case the contrast of a target experiences a crossover event and disappears for one polarization while it presents a strong contrast (9 K) with the other polarization. Experimental results are shown along with a simulation of the scene using a ray tracing program.

  18. Escape from intermittent repellers: periodic orbit theory for crossover from exponential to algebraic decay.

    PubMed

    Dahlqvist, P

    1999-12-01

    We apply periodic orbit theory to study the asymptotic distribution of escape times from an intermittent map. The dynamical zeta function exhibits a branch point which is associated with an asymptotic power law escape. By an analytic continuation technique we compute a pair of complex conjugate zeroes beyond the branch point, associated with a preasymptotic exponential decay. The crossover time from an exponential to a power law is also predicted. The theoretical predictions are confirmed by numerical simulation. Applications to conductance fluctuations in quantum dots are discussed.

  19. Diffusionless phase transition with two order parameters in spin-crossover solids

    SciTech Connect

    Gudyma, Iurii Ivashko, Victor; Linares, Jorge

    2014-11-07

    The quantitative analysis of the interface boundary motion between high-spin and low-spin phases is presented. The nonlinear effect of the switching front rate on the temperature is shown. A compressible model of spin-crossover solid is studied in the framework of the Ising-like model with two-order parameters under statistical approach, where the effect of elastic strain on interaction integral is considered. These considerations led to examination of the relation between the order parameters during temperature changes. Starting from the phenomenological Hamiltonian, entropy has been derived using the mean field approach. Finally, the phase diagram, which characterizes the system, is numerically analyzed.

  20. Experimental Evidence for a Crossover between Two Distinct Mechanisms of Amorphization in Ice Ih under Pressure

    SciTech Connect

    Straessle, Thierry; Klotz, Stefan; Hamel, Gerard; Koza, Michael M.; Schober, Helmut

    2007-10-26

    We report neutron scattering data which reveal the central role of phonon softening leading to a negative melting line, solid-state amorphization, and negative thermal expansion of ice. We find that pressure-induced amorphization is due to mechanical melting at low temperatures, while at higher temperatures amorphization is governed by thermal melting (violations of Born's and Lindemann's criteria, respectively). This confirms earlier conjectures of a crossover between two distinct amorphization mechanisms and provides a natural explanation for the strong annealing observed in high-density amorphous ice.

  1. Simulations of Edge Effect in 1D Spin Crossover Compounds by Atom-Phonon Coupling Model

    NASA Astrophysics Data System (ADS)

    Linares, J.; Chiruta, D.; Jureschi, C. M.; Alayli, Y.; Turcu, C. O.; Dahoo, P. R.

    2016-08-01

    We used the atom-phonon coupling model to explain and illustrate the behaviour of a linear nano-chain of molecules. The analysis of the system's behaviour was performed using Free Energy method, and by applying Monte Carlo Metropolis (MCM) method which take into account the phonon contribution. In particular we tested both the MCM algorithm and the dynamic-matrix method and we expose how the thermal behaviour of a 1D spin crossover system varies as a function of different factors. Furthermore we blocked the edge atoms of the chain in its high spin state to study the effect on the system's behaviour.

  2. Crossover behavior of the anomalous Hall effect and anomalous nernst effect in itinerant ferromagnets.

    PubMed

    Miyasato, T; Abe, N; Fujii, T; Asamitsu, A; Onoda, S; Onose, Y; Nagaosa, N; Tokura, Y

    2007-08-24

    The anomalous Hall effect (AHE) and anomalous Nernst effect (ANE) are experimentally investigated in a variety of ferromagnetic metals including pure transition metals, oxides, and chalcogenides, whose resistivities range over 5 orders of magnitude. For these ferromagnets, the transverse conductivity sigma{xy} versus the longitudinal conductivity sigma{xx} shows a crossover behavior with three distinct regimes in accordance qualitatively with a recent unified theory of the intrinsic and extrinsic AHE. We also found that the transverse Peltier coefficient alpha{xy} for the ANE obeys the Mott rule. These results offer a coherent and semiquantitative understanding of the AHE and ANE to an issue of controversy for many decades.

  3. Kinetic Roughening with Surface Diffusion: Crossover from Ramified Aggregates to Continuous Films on Liquid Surfaces

    NASA Astrophysics Data System (ADS)

    Lv, Neng; Zhang, Chu-Hang; Yang, Bo; Pan, Qi-Fa; Ye, Gao-Xiang

    2012-09-01

    Ramified iron aggregates are fabricated on silicone oil surface by thermal evaporation method at room temperature and the crossover from ramified aggregates to continuous films is studied by atomic force microscopy. It is shown that the aggregates are composed of numerous granules with the average diameter around 34 nm. The dynamic scaling analysis shows that the growth exponent β = 0.23 ± 0.02 and the roughness exponent α evolves from 0.65 to 0.42 with the nominal film thickness, indicating a roughening behavior transfer may exist during the growth process. The physical interpretation for the scaling behavior is presented.

  4. Manager Characteristics and Employee Job Insecurity around a Merger Announcement: The Role of Status and Crossover

    PubMed Central

    Lam, Jack; Fox, Kimberly; Fan, Wen; Moen, Phyllis; Kelly, Erin; Hammer, Leslie; Kossek, Ellen

    2014-01-01

    Most existing research theorizes individual factors as predictors of perceived job insecurity. Incorporating contextual and organizational factors at an information technology organization where a merger was announced during data collection, we draw on status expectations and crossover theories to investigate whether managers’ characteristics and insecurity shape their employees’ job insecurity. We find having an Asian as opposed to a White manager is associated with lower job insecurity, while managers’ own insecurity positively predicts employees’ insecurity. Also contingent on the organizational climate, managers’ own tenure buffers, and managers’ perceived job insecurity magnifies insecurity of employees interviewed after a merger announcement, further specifying status expectations theory by considering context. PMID:26190868

  5. Crossover from antipersistent to persistent behavior in time series possessing the generalyzed dynamic scaling law

    NASA Astrophysics Data System (ADS)

    Balankin, Alexander S.; Morales Matamoros, Oswaldo; Gálvez M., Ernesto; Pérez A., Alfonso

    2004-03-01

    The behavior of crude oil price volatility is analyzed within a conceptual framework of kinetic roughening of growing interfaces. We find that the persistent long-horizon volatilities satisfy the Family-Viscek dynamic scaling ansatz, whereas the mean-reverting in time short horizon volatilities obey the generalized scaling law with continuously varying scaling exponents. Furthermore we find that the crossover from antipersistent to persistent behavior is accompanied by a change in the type of volatility distribution. These phenomena are attributed to the complex avalanche dynamics of crude oil markets and so a similar behavior may be observed in a wide variety of physical systems governed by avalanche dynamics.

  6. Crossover from 2D to 3D in a Weakly Interacting Fermi Gas

    SciTech Connect

    Dyke, P.; Kuhnle, E. D.; Hu, H.; Mark, M.; Hoinka, S.; Lingham, M.; Hannaford, P.; Vale, C. J.; Whitlock, S.

    2011-03-11

    We have studied the transition from two to three dimensions in a low temperature weakly interacting {sup 6}Li Fermi gas. Below a critical atom number N{sub 2D} only the lowest transverse vibrational state of a highly anisotropic oblate trapping potential is occupied and the gas is two dimensional. Above N{sub 2D} the Fermi gas enters the quasi-2D regime where shell structure associated with the filling of individual transverse oscillator states is apparent. This dimensional crossover is demonstrated through measurements of the cloud size and aspect ratio versus atom number.

  7. Dimensional crossover of free exciton diffusion in etched GaAs wire structures

    NASA Astrophysics Data System (ADS)

    Bieker, S.; Stühler, R.; Kiessling, T.; Ossau, W.; Molenkamp, L. W.

    2015-09-01

    We report on low-temperature spatially resolved photoluminescence spectroscopy to study the diffusion of free excitons in etched wire structures of high-purity GaAs. We assess the stationary diffusion profiles by the free exciton second LO-phonon replica to circumvent the inherent interpretation ambiguities of the previously investigated free exciton zero-phonon line. Moreover, strictly resonant optical excitation prevents the distortion of the diffusion profiles due to local heating in the carrier system. We observe a dimensional crossover from 2D to 1D exciton diffusion when the lateral wire width falls below the diffusion length.

  8. Resonant instability near the two-ion crossover frequency in the Io plasma torus

    NASA Astrophysics Data System (ADS)

    Thorne, R. M.; Moses, J. J.

    1985-07-01

    Thorne and Scarf (1984) have presented evidence for the existence of intense low-frequency fluctuating electric fields in the Io plasma torus. Two distinct mechanisms have been proposed for this phenomenon, namely, ion cyclotron instability which occurs at intermediate latitude, and whistler instability near the equator. The present investigation is concerned with a quantitative appraisal of each of these mechanisms, taking into account an evaluation of the net convective growth rate of waves along ray paths which traverse the Io torus. Aspects of wave propagation near the crossover frequency are considered along with questions regarding the resonant interaction with energetic particles.

  9. BCS-BEC crossover in two dimensions: A quantum Monte Carlo study

    SciTech Connect

    Bertaina, G.

    2012-09-26

    We investigate the crossover from Bardeen-Cooper-Schrieffer (BCS) superfluidity to Bose-Einstein condensation (BEC) in a two-dimensional Fermi gas at T= 0 using the fixed-node diffusion Monte Carlo method. We calculate the equation of state and the gap parameter as a function of the interaction strength, observing large deviations compared to mean-field predictions. In the BEC regime our results show the important role of dimer-dimer and atom-dimer interaction effects that are completely neglected in the mean-field picture. We also consider the highly polarized gas and the competition between a polaronic and a molecular picture.

  10. 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

  11. The budding yeast Msh4 protein functions in chromosome synapsis and the regulation of crossover distribution.

    PubMed Central

    Novak, J E; Ross-Macdonald, P B; Roeder, G S

    2001-01-01

    The budding yeast MSH4 gene encodes a MutS homolog produced specifically in meiotic cells. Msh4 is not required for meiotic mismatch repair or gene conversion, but it is required for wild-type levels of crossing over. Here, we show that a msh4 null mutation substantially decreases crossover interference. With respect to the defect in interference and the level of crossing over, msh4 is similar to the zip1 mutant, which lacks a structural component of the synaptonemal complex (SC). Furthermore, epistasis tests indicate that msh4 and zip1 affect the same subset of meiotic crossovers. In the msh4 mutant, SC formation is delayed compared to wild type, and full synapsis is achieved in only about half of all nuclei. The simultaneous defects in synapsis and interference observed in msh4 (and also zip1 and ndj1/tam1) suggest a role for the SC in mediating interference. The Msh4 protein localizes to discrete foci on meiotic chromosomes and colocalizes with Zip2, a protein involved in the initiation of chromosome synapsis. Both Zip2 and Zip1 are required for the normal localization of Msh4 to chromosomes, raising the possibility that the zip1 and zip2 defects in crossing over are indirect, resulting from the failure to localize Msh4 properly. PMID:11454751

  12. Spin state of spin-crossover complexes: From single molecules to ultrathin films

    NASA Astrophysics Data System (ADS)

    Gruber, Manuel; Davesne, Vincent; Bowen, Martin; Boukari, Samy; Beaurepaire, Eric; Wulfhekel, Wulf; Miyamachi, Toshio

    2014-05-01

    The growth of spin-crossover Fe(1,10-phenanthroline)2(NCS)2 molecules on Cu(100) surfaces in the coverage range from 0.1 to 1.8 molecular layers was studied using a scanning tunneling microscope (STM) operated in ultrahigh vacuum at low temperature (≈4 K). STM imaging allowed us to extract the molecular adsorption geometry. While the first-layer molecules point their NCS groups toward the surface and their phenanthroline groups upwards, the adsorption geometry is reversed for the molecules in the second layer. For submonolayer coverages, a coexistence of molecules in the high- and low-spin states was found that is not correlated with the coverage. This coexistence is reduced for second-layer molecules, leading to a dominant spin state at low temperatures. Differential conductance spectra acquired at negative bias voltage on first- and second-layer molecules suggest that second-layer molecules are in the high-spin state and are partially electronically decoupled from the substrate. Furthermore, increasing the tip-to-sample voltage reduces the distance between the two lobes of the molecule. The current dependence of this effect suggests that a smooth spin crossover from a high- to a low-spin state occurs with increasing sample voltage. This analog spin-state switching is well described within a simple transition-state model involving modifications to the energy barriers between low- and high-spin states due to a tip-induced electric field through the Stark effect.

  13. An exercise program to prevent falls in institutionalized elderly with cognitive deficits: a crossover pilot study.

    PubMed

    DeSure, Ariell R; Peterson, Karen; Gianan, Faith V; Pang, Lorrin

    2013-11-01

    Falls are the leading cause of injury among older adults in the United States, with the institutionalized elderly at elevated risk for injury and death. Physical weakness and mental frailty, prevalent in institutionalized elderly, are major risk factors for falls. The purpose of this study was to evaluate a program that addresses both the physical and mental aspects of exercise to reduce falls in institutionalized elderly. Twenty-seven volunteer subjects residing in an assisted living facility participated in the 24 week randomized crossover study. After demographic, fall history, and mental status examinations, subjects were randomly assigned first to ten weeks of either an exercise class or a control group, followed by a four week "washout period" of no activity, then cross assigned to ten weeks as either a control group or exercise class, respectively. Falls as well as mental status changes were monitored during the study. After adjusting for differences in baseline risk between the control and treatment groups, and for potential residual effects of the treatment during the crossover phase, a statistically significant (P = .025) reduction in falls was found during treatment compared to the control periods. No change in mental status was seen. This small, pilot study shows that exercise programs, which emphasize mental strengthening as well as physical fitness, have the potential to reduce falls among mentally impaired, institutionalized seniors.

  14. Fragile to strong crossover at the Widom line in supercooled aqueous solutions of NaCl

    SciTech Connect

    Gallo, P.; Corradini, D.; Rovere, M.

    2013-11-28

    We study by molecular dynamics simulations the dynamical properties of an aqueous solution of NaCl at a concentration of 0.67 mol/kg upon supercooling. In a previous study of the same ionic solution, we have located the liquid-liquid critical point (LLCP) and determined the Widom line connected to the liquid-liquid transition. We present here the results obtained from the study of the self-intermediate scattering function in a large range of temperatures and densities approaching the LLCP. The structural relaxation is in agreement with the mode coupling theory (MCT) in the region of mild supercooling. In the deeper supercooled region the α-relaxation time as function of temperature deviates from the MCT power law prediction showing a crossover from a fragile to a strong behavior. This crossover is found upon crossing the Widom line. The same trend was found in bulk water upon supercooling and it appears almost unchanged by the interaction with ions apart from a shift in the thermodynamic plane toward lower pressures and higher temperatures. These results show that the phenomenology of supercooled water transfers from bulk to solution where the study of the supercooled region is experimentally less difficult.

  15. Critical phenomena in ionic fluids: A systematic investigation of the crossover behavior

    SciTech Connect

    Narayanan, T.; Pitzer, K.S.

    1995-05-22

    The critical behavior of turbidity for an array of ionic fluids is reported. The ionic fluid is comprised of a low melting organic salt in an organic solvent, and the critical temperature ({ital T}{sub {ital c}}) refers to the liquid--liquid coexistence. The phase separation is driven, predominantly, by Coulombic interactions in the low dielectric constant ({epsilon}) solvents and, primarily, by solvophobic effects in the high {epsilon} solvents. For the moderately Coulombic case, the critical exponents of osmotic compressibility and correlation length ({gamma} and {nu}, respectively), which are deduced from turbidity, exhibit a {ital crossover} from their Ising to mean-field values when moved away from the {ital T}{sub {ital c}}. The crossover region moves closer to {ital T}{sub {ital c}} as the effective {epsilon} of the solvent is decreased. For the solvophobic case, the critical behavior of turbidity can be adequately described by Ising critical exponents without correction-to-scaling terms. In addition, several specific features of this class of ionic fluids are presented. Some potential factors that influence the values of the critical exponents are also discussed.

  16. Crossover from fractal capillary fingering to compact flow: The effect of stable viscosity ratios

    SciTech Connect

    Ferer, M.V.; Bromhal, G.S.; Smith, D.H.

    2007-10-01

    Using a standard pore-level model, which includes both viscous and capillary forces, we have studied the injection of a viscous, nonwetting fluid into a two-dimensional porous medium saturated with a less viscous, wetting fluid, i.e., drainage with favorable viscosity ratios, M>=1. We have observed a crossover from fractal capillary fingering to standard compact flow at a characteristic time, which decreases with increased capillary number and/or viscosity ratio. We have tested an earlier prediction for the dependence of this crossover upon viscosity ratio and capillary number using our data for a wide-but-physical range of capillary numbers and viscosity ratios. We find good agreement between the predicted behavior and our results from pore-level modeling. Furthermore, we show that this agreement is not affected by changes in the random distribution of pore throat radii or by changes in the coordination number, suggesting that the prediction is universal, i.e., valid for any porous medium structure, as expected from the general nature of the derivation of the prediction. Furthermore, this agreement indicates that the prediction correctly accounts for dependence of the flow upon capillary number and viscosity ratios, thereby enabling predictions for interfacial advance and width as well as saturation and fractional flow profiles. Also this agreement supports the validity of the general theoretical development lending credence to the three-dimensional predictions.

  17. Crossover from fractal capillary fingering to compact flow: The effect of stable viscosity ratios

    SciTech Connect

    Ferer, M.; Bromhal, Grant S.; Smith, Duane H.

    2007-10-01

    Using a standard pore-level model, which includes both viscous and capillary forces, we have studied the injection of a viscous, nonwetting fluid into a two-dimensional porous medium saturated with a less viscous, wetting fluid, i.e., drainage with favorable viscosity ratios, M≥1. We have observed a crossover from fractal capillary fingering to standard compact flow at a characteristic time, which decreases with increased capillary number and/or viscosity ratio. We have tested an earlier prediction for the dependence of this crossover upon viscosity ratio and capillary number using our data for a wide-but-physical range of capillary numbers and viscosity ratios. We find good agreement between the predicted behavior and our results from pore-level modeling. Furthermore, we show that this agreement is not affected by changes in the random distribution of pore throat radii or by changes in the coordination number, suggesting that the prediction is universal, i.e., valid for any porous medium structure, as expected from the general nature of the derivation of the prediction. Furthermore, this agreement indicates that the prediction correctly accounts for dependence of the flow upon capillary number and viscosity ratios, thereby enabling predictions for interfacial advance and width as well as saturation and fractional flow profiles. Also this agreement supports the validity of the general theoretical development lending credence to the three-dimensional predictions

  18. Crossover from fractal capillary fingering to compact flow: The effect of stable viscosity ratios.

    PubMed

    Ferer, M; Bromhal, Grant S; Smith, Duane H

    2007-10-01

    Using a standard pore-level model, which includes both viscous and capillary forces, we have studied the injection of a viscous, nonwetting fluid into a two-dimensional porous medium saturated with a less viscous, wetting fluid, i.e., drainage with favorable viscosity ratios, M> or =1 . We have observed a crossover from fractal capillary fingering to standard compact flow at a characteristic time, which decreases with increased capillary number and/or viscosity ratio. We have tested an earlier prediction for the dependence of this crossover upon viscosity ratio and capillary number using our data for a wide-but-physical range of capillary numbers and viscosity ratios. We find good agreement between the predicted behavior and our results from pore-level modeling. Furthermore, we show that this agreement is not affected by changes in the random distribution of pore throat radii or by changes in the coordination number, suggesting that the prediction is universal, i.e., valid for any porous medium structure, as expected from the general nature of the derivation of the prediction. Furthermore, this agreement indicates that the prediction correctly accounts for dependence of the flow upon capillary number and viscosity ratios, thereby enabling predictions for interfacial advance and width as well as saturation and fractional flow profiles. Also this agreement supports the validity of the general theoretical development lending credence to the three-dimensional predictions. PMID:17995103

  19. Mte1 interacts with Mph1 and promotes crossover recombination and telomere maintenance

    PubMed Central

    Silva, Sonia; Altmannova, Veronika; Luke-Glaser, Sarah; Henriksen, Peter; Gallina, Irene; Yang, Xuejiao; Choudhary, Chunaram; Luke, Brian; Krejci, Lumir

    2016-01-01

    Mph1 is a member of the conserved FANCM family of DNA motor proteins that play key roles in genome maintenance processes underlying Fanconi anemia, a cancer predisposition syndrome in humans. Here, we identify Mte1 as a novel interactor of the Mph1 helicase in Saccharomyces cerevisiae. In vitro, Mte1 (Mph1-associated telomere maintenance protein 1) binds directly to DNA with a preference for branched molecules such as D loops and fork structures. In addition, Mte1 stimulates the helicase and fork regression activities of Mph1 while inhibiting the ability of Mph1 to dissociate recombination intermediates. Deletion of MTE1 reduces crossover recombination and suppresses the sensitivity of mph1Δ mutant cells to replication stress. Mph1 and Mte1 interdependently colocalize at DNA damage-induced foci and dysfunctional telomeres, and MTE1 deletion results in elongated telomeres. Taken together, our data indicate that Mte1 plays a role in regulation of crossover recombination, response to replication stress, and telomere maintenance. PMID:26966248

  20. Dynamic heterogeneity in crossover spin facilitated model of supercooled liquid and fractional Stokes-Einstein relation

    SciTech Connect

    Choi, Seo-Woo; Kim, Soree; Jung, YounJoon

    2015-06-28

    Kinetically constrained models have gained much interest as models that assign the origins of interesting dynamic properties of supercooled liquids to dynamical facilitation mechanisms that have been revealed in many experiments and numerical simulations. In this work, we investigate the dynamic heterogeneity in the fragile-to-strong liquid via Monte Carlo method using the model that linearly interpolates between the strong liquid-like behavior and the fragile liquid-like behavior by an asymmetry parameter b. When the asymmetry parameter is sufficiently small, smooth fragile-to-strong transition is observed both in the relaxation time and the diffusion constant. Using these physical quantities, we investigate fractional Stokes-Einstein relations observed in this model. When b is fixed, the system shows constant power law exponent under the temperature change, and the exponent has the value between that of the Frederickson-Andersen model and the East model. Furthermore, we investigate the dynamic length scale of our systems and also find the crossover relation between the relaxation time. We ascribe the competition between energetically favored symmetric relaxation mechanism and entropically favored asymmetric relaxation mechanism to the fragile-to-strong crossover behavior.