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Sample records for 3-way crossover design

  1. 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…

  2. Lubiprostone decreases the small bowel transit time by capsule endoscopy: an exploratory, randomised, double-blind, placebo-controlled 3-way crossover study.

    PubMed

    Matsuura, Mizue; Inamori, Masahiko; Endo, Hiroki; Matsuura, Tetsuya; Kanoshima, Kenji; Inoh, Yumi; Fujita, Yuji; Umezawa, Shotaro; Fuyuki, Akiko; Uchiyama, Shiori; Higurashi, Takuma; Ohkubo, Hidenori; Sakai, Eiji; Iida, Hiroshi; Nonaka, Takashi; Futagami, Seiji; Kusakabe, Akihiko; Maeda, Shin; Nakajima, Atsushi

    2014-01-01

    The aim of this study was to investigate the usefulness of lubiprostone for bowel preparation and as a propulsive agent in small bowel endoscopy. Six healthy male volunteers participated in this randomized, 3-way crossover study. The subjects received a 24 μg tablet of lubiprostone 60 minutes prior to the capsule ingestion for capsule endoscopy (CE) and a placebo tablet 30 minutes before the capsule ingestion (L-P regimen), a placebo tablet 60 minutes prior to CE and a 24 μg tablet of lubiprostone 30 minutes prior to CE (P-L regimen), or a placebo tablet 60 minutes prior to r CE and a placebo tablet again 30 minutes prior to CE (P-P regimen). The quality of the capsule endoscopic images and the amount of water in the small bowel were assessed on 5-point scale. The median SBTT was 178.5 (117-407) minutes in the P-P regimen, 122.5 (27-282) minutes in the L-P regimen, and 110.5 (11-331) minutes in the P-L regimen (P = 0.042). This study showed that the use of lubiprostone significantly decreased the SBTT. We also confirmed that lubiprostone was effective for inducing water secretion into the small bowel during CE. PMID:25614738

  3. Lubiprostone Decreases the Small Bowel Transit Time by Capsule Endoscopy: An Exploratory, Randomised, Double-Blind, Placebo-Controlled 3-Way Crossover Study

    PubMed Central

    Matsuura, Mizue; Inamori, Masahiko; Endo, Hiroki; Matsuura, Tetsuya; Kanoshima, Kenji; Inoh, Yumi; Fujita, Yuji; Umezawa, Shotaro; Fuyuki, Akiko; Uchiyama, Shiori; Higurashi, Takuma; Ohkubo, Hidenori; Sakai, Eiji; Iida, Hiroshi; Nonaka, Takashi; Futagami, Seiji; Kusakabe, Akihiko; Maeda, Shin; Nakajima, Atsushi

    2014-01-01

    The aim of this study was to investigate the usefulness of lubiprostone for bowel preparation and as a propulsive agent in small bowel endoscopy. Six healthy male volunteers participated in this randomized, 3-way crossover study. The subjects received a 24 μg tablet of lubiprostone 60 minutes prior to the capsule ingestion for capsule endoscopy (CE) and a placebo tablet 30 minutes before the capsule ingestion (L-P regimen), a placebo tablet 60 minutes prior to CE and a 24 μg tablet of lubiprostone 30 minutes prior to CE (P-L regimen), or a placebo tablet 60 minutes prior to r CE and a placebo tablet again 30 minutes prior to CE (P-P regimen). The quality of the capsule endoscopic images and the amount of water in the small bowel were assessed on 5-point scale. The median SBTT was 178.5 (117–407) minutes in the P-P regimen, 122.5 (27–282) minutes in the L-P regimen, and 110.5 (11–331) minutes in the P-L regimen (P = 0.042). This study showed that the use of lubiprostone significantly decreased the SBTT. We also confirmed that lubiprostone was effective for inducing water secretion into the small bowel during CE. PMID:25614738

  4. 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

  5. [Case-crossover design: Basic essentials and applications].

    PubMed

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

    2009-01-01

    Case-crossover analysis is an observational epidemiological design that was proposed by Maclure in 1991 to assess whether a given intermittent or unusual exposure may have triggered an immediate short-term, acute event. The present article outlines the basics of case-crossover designs, as well as their applications and limitations. The case-crossover design is based on exclusively selecting case subjects. To calculate relative risk, exposure during the period of time prior to the event (case period) is compared against the same subject's exposure during one or more control periods. This method is only appropriate when the exposures are transient in time and have acute short-term effects. For exposures in which there is no trend, a unidirectional approach is the most frequent and consists of selecting one or more control periods prior to the case period. When the exposure displays a time trend (e.g., air pollution), a unidirectional approach will yield biased estimates, and therefore bidirectional case-crossover designs are used, which select control time intervals preceding and subsequent to that of the event. The case-crossover design is being increasingly used across a wide range of fields, including factors triggering traffic, occupational and domestic accidents and acute myocardial infarction, and those involved in air pollution and health and pharmacoepidemiology, among others. Insofar as data-analysis is concerned, case-crossover designs can generally be regarded as matched case-control studies and consequently conditional logistic regression can be applied. Lastly, this study analyzes practical examples of distinct applications of the case-crossover design. PMID:19303669

  6. Interference-mediated synaptonemal complex formation with embedded crossover designation

    PubMed Central

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

    2014-01-01

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

  7. 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

  8. 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.

  9. 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

  10. Crossover design and its application in late-phase diabetes studies.

    PubMed

    Wang, Tao; Malone, James; Fu, Haoda; Heilmann, Cory; Qu, Yongming; Huster, William J

    2016-09-01

    Crossover design has been widely used in late-phase clinical studies, as well as in pharmacokinetic and pharmacodynamic, bioequivalence, and medical device studies; however, its interpretability and applicability continue to be debated. Herein we provide discussions around a crossover design's scientific benefit, applicability, and how it can be implemented in late-phase diabetes studies by properly handling key issues: carryover effect, washout period, and baseline selection. Specifically, detailed considerations are provided about the validity and situations of having appropriate length of study duration to deal with carryover effects so that a washout period may not be needed. A simulation study and data mining results on 12 crossover late-phase insulin clinical trials are presented to examine the discussion points and proposals. PMID:27100270

  11. 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

  12. 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…

  13. 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

  14. A randomized, open-label 3-way crossover study to investigate the relative bioavailability and bioequivalence of crushed sildenafil 20 mg tablets mixed with apple sauce, extemporaneously prepared suspension (EP), and intact sildenafil 20 mg tablets in healthy volunteers under fasting conditions.

    PubMed

    Gao, Xiang; Ndongo, Marie-Noella; Checchio, Tina M; Cook, Jack; Duncan, Barbara; LaBadie, Robert R

    2015-01-01

    The relative bioavailability and bioequivalence of 20-mg doses of a pediatric formulation of sildenafil extemporaneous preparation suspension (EP; 10 mg/mL), the sildenafil 20-mg intact tablet and the crushed sildenafil 20-mg tablet mixed with apple sauce were assessed in a single-dose, randomized, open-label, 3-way crossover study with 18 healthy adult volunteers. Blood samples were collected at predefined times and analyzed for sildenafil plasma concentrations. Natural log-transformed sildenafil pharmacokinetic parameters (Cmax , AUClast , and AUCinf ) were used to estimate relative bioavailability and construct 90% confidence intervals (CI) using a mixed-effects model. Bioequivalence was concluded among the three formulations with one exception, in which the EP suspension showed a 15% decrease in Cmax with a lower 90% CI of 76% compared with the intact tablet. The 15% decrease in sildenafil Cmax is not considered to be clinically relevant. Therefore, the EP suspension is considered to be an appropriate pediatric formulation. All 3 formulations were well tolerated in healthy adult volunteers. PMID:27128005

  15. Multilevel data analysis of a crossover designed human nutritional intervention study.

    PubMed

    van Velzen, Ewoud J J; Westerhuis, Johan A; van Duynhoven, John P M; van Dorsten, Ferdi A; Hoefsloot, Huub C J; Jacobs, Doris M; Smit, Suzanne; Draijer, Richard; Kroner, Christine I; Smilde, Age K

    2008-10-01

    A new method is introduced for the analysis of 'omics' data derived from crossover designed drug or nutritional intervention studies. The method aims at finding systematic variations in metabolic profiles after a drug or nutritional challenge and takes advantage of the crossover design in the data. The method, which can be considered as a multivariate extension of a paired t test, generates different multivariate submodels for the between- and the within-subject variation in the data. A major advantage of this variation splitting is that each submodel can be analyzed separately without being confounded with the other variation sources. The power of the multilevel approach is demonstrated in a human nutritional intervention study which used NMR-based metabolomics to assess the metabolic impact of grape/wine extract consumption. The variations in the urine metabolic profiles are studied between and within the human subjects using the multilevel analysis. After variation splitting, multilevel PCA is used to investigate the experimental and biological differences between the subjects, whereas a multilevel PLS-DA model is used to reveal the net treatment effect within the subjects. The observed treatment effect is validated with cross model validation and permutations. It is shown that the statistical significance of the multilevel classification model ( p < 0.0002) is a major improvement compared to a ordinary PLS-DA model ( p = 0.058) without variation splitting. Finally, rank products are used to determine which NMR signals are most important in the multilevel classification model. PMID:18754629

  16. Practical approaches for design and analysis of clinical trials of infertility treatments: crossover designs and the Mantel-Haenszel method are recommended.

    PubMed

    Takada, Michihiro; Sozu, Takashi; Sato, Tosiya

    2015-01-01

    Crossover designs have some advantages over standard clinical trial designs and they are often used in trials evaluating the efficacy of treatments for infertility. However, clinical trials of infertility treatments violate a fundamental condition of crossover designs, because women who become pregnant in the first treatment period are not treated in the second period. In previous research, to deal with this problem, some new designs, such as re-randomization designs, and analysis methods including the logistic mixture model and the beta-binomial mixture model were proposed. Although the performance of these designs and methods has previously been evaluated in large-scale clinical trials with sample sizes of more than 1000 per group, the actual sample sizes of infertility treatment trials are usually around 100 per group. The most appropriate design and analysis for these moderate-scale clinical trials are currently unclear. In this study, we conducted simulation studies to determine the appropriate design and analysis method of moderate-scale clinical trials for irreversible endpoints by evaluating the statistical power and bias in the treatment effect estimates. The Mantel-Haenszel method had similar power and bias to the logistic mixture model. The crossover designs had the highest power and the smallest bias. We recommend using a combination of the crossover design and the Mantel-Haenszel method for two-period, two-treatment clinical trials with irreversible endpoints. PMID:25776032

  17. 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

  18. 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.

  19. 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

  20. A randomized, crossover design study of sevelamer carbonate powder and sevelamer hydrochloride tablets in chronic kidney disease patients on haemodialysis

    PubMed Central

    Fan, Stanley; Ross, Calum; Mitra, Sandip; Kalra, Philip; Heaton, Jeremy; Hunter, John; Plone, Melissa; Pritchard, Nick

    2009-01-01

    Background. Sevelamer carbonate is an improved, buffered form of sevelamer hydrochloride developed for the treatment of hyperphosphataemia in CKD patients. Sevelamer carbonate formulated as a powder for oral suspension presents a novel, patient-friendly alternative to tablet phosphate binders. This study compared the safety and efficacy of sevelamer carbonate powder with sevelamer hydrochloride tablets in CKD patients on haemodialysis. Methods. This was a multi-centre, open-label, randomized, crossover design study. Thirty-one haemodialysis patients were randomly assigned to either sevelamer carbonate powder or sevelamer hydrochloride tablets for 4 weeks followed by a crossover to the other regimen for an additional 4 weeks. Results. The mean serum phosphorus was 1.6 ± 0.5 mmol/L (5.0 ± 1.5 mg/dL) during sevelamer carbonate powder treatment and 1.7 ± 0.4 mmol/L (5.2 ± 1.1 mg/dL) during sevelamer hydrochloride tablet treatment. Sevelamer carbonate powder and sevelamer hydrochloride tablets are equivalent in controlling serum phosphorus; the geometric least square mean ratio was 0.95 (90% CI 0.87–1.03). No statistically significant or clinically meaningful differences were observed in calcium × phosphorus product and lipid levels between sevelamer carbonate powder and sevelamer hydrochloride tablets. Serum bicarbonate levels increased 2.7 ± 3.7 mmol/L (2.7 ± 3.7 mEq/L) during sevelamer carbonate treatment. No statistically significant change in bicarbonate was observed during sevelamer hydrochloride treatment. Sevelamer carbonate powder and sevelamer hydrochloride were well tolerated during this study. Conclusions. Sevelamer carbonate powder and sevelamer hydrochloride tablets are equivalent in controlling serum phosphorus and well tolerated in CKD patients on haemodialysis. Bicarbonate levels improved only during sevelamer carbonate treatment. Sevelamer carbonate powder should provide a welcomed new option for the treatment of hyperphosphataemia for CKD

  1. 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

  2. Beneficial effect of tagatose consumption on postprandial hyperglycemia in Koreans: a double-blind crossover designed study.

    PubMed

    Kwak, Jung Hyun; Kim, Min Sun; Lee, Jin Hee; Yang, Yoon Jung; Lee, Ki Ho; Kim, Oh Yoen; Lee, Jong Ho

    2013-08-01

    The present study determined the effect of tagatose supplementation on postprandial hyperglycemia in normal (n = 54) and hyperglycemic subjects [n = 40, impaired fasting glucose (IFG) and newly diagnosed type 2 diabetes]. In a double-blind crossover designed study, study subjects were randomly assigned to consume a sucralose-erythritol drink (the placebo) or a tagatose-containing drink (the test) with a seven-day interval. Finally, 85 subjects completed the study (normal, n = 52; hyperglycemic, n = 33). Blood samples were collected at 0, 30, 60 and 120 min after ingestion and analyzed for fasting and postprandial levels of glucose, insulin and C-peptide. Basic anthropometric parameters and lipid files were also measured. Hyperglycemic subjects were basically older and heavier, and showed higher levels of triglyceride, total- and LDL-cholesterols and apolipoprotein AI and B compared with normal subjects. After consuming the tagatose (5 g)-containing drink, hyperglycemic subjects had a significant reduction in serum levels of glucose at 120 min (p = 0.019) and glucose area under the curve (AUC) (p = 0.017), however these were not observed in normal subjects. When ages were matched between the two groups, the glucose response patterns were shown to be similar. Additionally, normal subjects who received a high-dose of tagatose-containing drinks (10 g) showed significantly lower levels of insulin at 30 min (p = 0.004) and 60 min (p = 0.011), insulin AUC (p = 0.009), and C-peptide at 30 min (p = 0.004), 60 min (p = 0.011) and C-peptide AUC (p = 0.023). In conclusion, a single dietary supplement in the form of a tagatose-containing drink may be beneficial for controlling postprandial glycemic response in Koreans. PMID:23760573

  3. 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

  4. 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

  5. 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

  6. 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. PMID:26017321

  7. Event-Specific Risk Factors Predicting Episodes of Unprotected Anal Intercourse with Male Nonregular Partners among Men Who Have Sex with Men Using Case-Crossover Study Design

    PubMed Central

    Li, Jinghua; Lau, Joseph T. F.; Gu, Jing; Hao, Chun; Lai, Coco H. Y.

    2014-01-01

    This study investigated event-specific factors that determine episodes of unprotected and protected anal intercourse (UAI and PAI) among 215 men who have sex with men (MSM), who used condoms inconsistently with nonregular partners (NRP) in the last six months, in Hong Kong. A case-crossover study design was used. Lower likelihood of episodes involving UAI with NRP was associated with (1) five partner attributes (NRP were <35 years old, at least three previous anal sex experiences with the NRP, perception that participant and the NRP had asymmetrical sexual experience, perception that the NRP was feminine, and liking toward the NRP; OR = 0.16–0.52), (2) six situational variables (the participant having had UAI with another man in the last week, having discussed condom use, perception that the NRP liked to use condom, partner's suggestion to have PAI, participant's suggestion to have PAI, and participant's plan to use condoms; OR = 0.11–0.39), and (3) four environmental/setting variables (condoms already placed at the venue, display of condom use promotion materials, participant's possession of a condom, and the NRP possessed a condom; OR = 0.27–0.45). HIV prevention targeting MSM should focus on event-specific protective factors, which may be different from those obtained from studies distinguishing condom users versus nonusers. PMID:25136589

  8. A comparison of triclosan and stannous fluoride toothpastes for inhibition of plaque regrowth. A crossover study designed to assess carry over.

    PubMed

    Binney, A; Addy, M; Owens, J; Faulkner, J

    1997-03-01

    Some triclosan and stannous fluoride toothpastes have been shown effective in reducing plaque and more particularly gingivitis in home use studies. There have been few comparisons of such products for their chemical plaque inhibitory action divorced from the indeterminate variable of toothbrushing. This study was a randomised, single-blind, cross-over comparison of 4 products, in a 4-day plaque regrowth design, balanced for residual effects and involving 12 healthy dentate subjects. The test agents were a stannous fluoride toothpaste, a triclosan/copolymer toothpaste, a triclosan/zinc citrate toothpaste and water. On day 1 of each study period, subjects were rendered plaque free. For the following 4 days, each subject suspended normal toothcleaning and rinsed 2 x daily with the allocated treatment for 60 s under supervision. On day 5, plaque was scored by index. Washout periods of 2 1/2 days brushing with water alone, followed each treatment period. Pseudo treatment periods of 4 days, involving 2 x daily rinsing with water in the absence of toothbrushing, followed the normal washouts after the stannous fluoride and triclosan/zinc citrate treatments, giving a total of 6 treatment periods. This design permitted analyses for 1st-order-carry-over. Intention to treat analyses revealed all toothpastes were more effective than water but that there were no differences between the active treatments. Per protocol analysis gave essentially similar findings except that the difference in plaque in favour of the triclosan/zinc citrate toothpaste over water did not reach significance. There was no evidence of 1st-order-carry-over effects for the stannous fluoride or triclosan/zinc citrate toothpastes. Consistent with other studies it appears that stannous fluoride and triclosan can be formulated into toothpaste vehicles to provide plaque inhibitory effects. PMID:9083900

  9. 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

  10. 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

  11. 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

  12. 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.

  13. 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

  14. 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

  15. A crossover in the mechanical response of nanocrystalline ceramics.

    PubMed

    Szlufarska, Izabela; Nakano, Aiichiro; Vashishta, Priya

    2005-08-01

    Multimillion-atom molecular dynamics simulation of indentation of nanocrystalline silicon carbide reveals unusual deformation mechanisms in brittle nanophase materials, resulting from the coexistence of brittle grains and soft amorphous grain boundary phases. Simulations predict a crossover from intergranular continuous deformation to intragrain discrete deformation at a critical indentation depth. The crossover arises from the interplay between cooperative grain sliding, grain rotations, and intergranular dislocation formation similar to stick-slip behavior. The crossover is also manifested in switching from deformation dominated by indentation-induced crystallization to deformation dominated by disordering, leading to amorphization. This interplay between deformation mechanisms is critical for the design of ceramics with superior mechanical properties. PMID:16081730

  16. 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)

  17. 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

  18. Interpretation and bias in case-crossover studies.

    PubMed

    Redelmeier, D A; Tibshirani, R J

    1997-11-01

    The case-crossover design is an innovative epidemiologic technique with distinct strengths and limitations. We review the fundamental logic of this self-matching non-randomized design and direct attention to 15 concerns related to the available data, unavailable data, analytic technique, quantitative statistics, and etiologic model. Implications for each concern are discussed in the context of a recent report on whether cellular telephone calls are associated with an increased risk of a motor vehicle collision. We suggest that an understanding of the case-crossover design may help investigators explore selected questions in behavioral medical research. PMID:9393384

  19. 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.

  20. The differential effects of a complex protein drink versus isocaloric carbohydrate drink on performance indices following high-intensity resistance training: a two arm crossover design

    PubMed Central

    2013-01-01

    Background Post-workout nutrient timing and macronutrient selection are essential for recovery, glycogen replenishment and muscle protein synthesis (MPS). Performance repeatability, particularly after strenuous activity, can be influenced by substrate availability, recovery markers and perceived rate of exertion. This study compared the differential effects of a complex protein ready-to-drink beverage (VPX) and isocaloric carbohydrate beverage (iCHO) on performance—agility T-test, push-up test, 40-yard sprint, and rate of perceived exertion (RPE), following high-intensity resistance training (HIRT). Methods In a randomized, double blind two-arm crossover controlled trial, 15 subjects performed a 15–18 minute (2:1 work to rest) HIRT and then immediately drank one of the two treatments. After a 2-hour fast, subjects returned to execute the field tests and report RPE. The protocol was repeated one week later with the other treatment. Results There were no significant main effect differences in the agility T-test (p = 0.83), push-up (p = 0.21) sprint (p = 0.12), average agility RPE (p = 0.83), average push-up RPE (p = 0.81) or average sprint RPE (p = 0.66) between the two trials and the two treatments. The multivariate analysis yielded a cumulative significant interaction effect amongst the three performance variables after consuming VPX (p < 0.01). These results suggest a complex protein beverage is a better post-workout choice compared to an isocaloric carbohydrate beverage for repeated performance for activities that require multiple energy demands and athletic skills; however, this outcome was not observed for each single performance event or RPE. Conclusion When considering the collective physical effects of the agility T-test, push-up and sprint tests, a complex protein beverage may provide a recovery advantage as it relates to repeated-bout performance compared to an iCHO-only beverage. Additional research examining the chronic effects of post

  1. Eye Expert Dr. Emily Chew: 3 Ways to Keep Your Sight

    MedlinePlus

    ... Issues Feature: Vision Eye Expert Dr. Emily Chew: 3 Ways to Keep Your Sight Past Issues / Summer ... a healthy diet. New research shows that omega-3 fatty acids may protect the retina from wear. ...

  2. 3-way Networks: Application of Hypergraphs for Modelling Increased Complexity in Comparative Genomics

    SciTech Connect

    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.

  3. 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.

  4. Microelectronic superconducting crossover and coil

    DOEpatents

    Wellstood, Frederick C.; Kingston, John J.; Clarke, John

    1994-01-01

    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.

  5. 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.

  6. A prospective randomised cross-over study of the effect of insulin analogues and human insulin on the frequency of severe hypoglycaemia in patients with type 1 diabetes and recurrent hypoglycaemia (the HypoAna trial): study rationale and design

    PubMed Central

    2012-01-01

    Background Severe hypoglycaemia still represents a significant problem in insulin-treated diabetes. Most patients do not experience severe hypoglycaemia often. However, 20% of patients with type 1 diabetes experience recurrent severe hypoglycaemia corresponding to at least two episodes per year. The effect of insulin analogues on glycaemic control has been documented in large trials, while their effect on the frequency of severe hypoglycaemia is less clear, especially in patients with recurrent severe hypoglycaemia. The HypoAna Trial is designed to investigate whether short-acting and long-acting insulin analogues in comparison with human insulin are superior in reducing the occurrence of severe hypoglycaemic episodes in patients with recurrent hypoglycaemia. This paper reports the study design of the HypoAna Trial. Methods/design The study is a Danish two-year investigator-initiated, prospective, randomised, open, blinded endpoint (PROBE), multicentre, cross-over trial investigating the effect of insulin analogues versus human insulin on the frequency of severe hypoglycaemia in subjects with type 1 diabetes. Patients are randomised to treatment with basal-bolus therapy with insulin detemir / insulin aspart or human NPH insulin / human regular insulin in random order. The major inclusion criterion is history of two or more episodes of severe hypoglycaemia in the preceding year. Discussion In contrast to almost all other studies in this field the HypoAna Trial includes only patients with major problems with hypoglycaemia. The HypoAna Trial will elucidate whether basal-bolus regimen with short-acting and long-acting insulin analogues in comparison with human insulin are superior in reducing occurrence of severe hypoglycaemic episodes in hypoglycaemia prone patients with type 1 diabetes. http://www.clinicaltrials.gov: NCT00346996. PMID:22727048

  7. 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

  8. DMDS or the 3-way: which is more effective in Georgia?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    During 2007 and 2008, Methyl Bromide alternatives were used on nearly 25 and 50% of Georgia’s fumigated plasticulture area, respectively. The primary alternative is the 3-Way (Telone II, chloropicrin, and metam). Dimethyl disulfide (DMDS) is nearing registration, providing a new alternative. All pro...

  9. An open-label, phase 2, single centre, randomized, crossover design bioequivalence study of AndroForte 5 testosterone cream and Testogel 1% testosterone gel in hypogonadal men: study LP101.

    PubMed

    Wittert, G A; Harrison, R W; Buckley, M J; Wlodarczyk, J

    2016-01-01

    We compared a novel 5% testosterone (T) cream (AndroForte 5, Lawley Pharmaceuticals, Australia) with a 1% T gel (Testogel, Besins Healthcare, Australia). Using an open-label crossover design, subjects were randomized to one of two treatment sequences using either the T gel or T cream first in a 1 : 1 ratio. Each treatment period was 30 days with a 7-14 days washout period between them. On Days 1 and 30 of each treatment period blood was sampled at -15, -5 min, 0, 2, 4, 5, 6, 7, 8, 9, 10, 12 and 16 h post study drug administration. Sixteen men with established androgen deficiency aged between 29 and 73 years, who had undertaken a washout from prior testosterone therapy participated in the study. One subject failed to complete both arms and another was excluded post-completion because of a major protocol violation. Bioequivalence was established based on key pharmacokinetic (PK) variables: AUC, C(avg), C(max), T(max), % fluctuation (with and without baseline correction) for the two formulations of testosterone on Day 1 and Day 30. The ratio and 90% CI of AUC 0.99 (0.86-1.14), C(max) 1.02 (0.84-1.24) and C(avg) 0.99 (0.86-1.14) for T cream/T gel were within the predetermined bio-equivalence criteria of 80% to 125% at Day 30. There were no statistically significant differences between secondary biochemical markers: serum dihydrotestosterone (DHT), oestradiol (E2), sex hormone-binding globulin (SHBG), luteinizing hormone (LH) and (FSH). The two testosterone formulations were shown to be bioequivalent. PMID:26754331

  10. 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.

  11. Becoming a crossover-competent DSB.

    PubMed

    Lake, Cathleen M; Hawley, R Scott

    2016-06-01

    The proper execution of meiotic recombination (or crossing over) is essential for chromosome segregation during the first meiotic division, and thus this process is regulated by multiple, and often elaborate, mechanisms. Meiotic recombination begins with the programmed induction of DNA double-strand breaks (DSBs), of which only a subset are selected to be repaired into crossovers. This crossover selection process is carried out by a number of pro-crossover proteins that regulate the fashion in which DSBs are repaired. Here, we highlight recent studies regarding the process of DSB fate selection by a family of pro-crossover proteins known as the Zip-3 homologs. PMID:26806636

  12. 24 CFR 3285.701 - Electrical crossovers.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 24 Housing and Urban Development 5 2012-04-01 2012-04-01 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...

  13. 24 CFR 3285.701 - Electrical crossovers.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 24 Housing and Urban Development 5 2014-04-01 2014-04-01 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...

  14. 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...

  15. 24 CFR 3285.701 - Electrical crossovers.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 24 Housing and Urban Development 5 2013-04-01 2013-04-01 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...

  16. 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...

  17. Brain histamine H1 receptor occupancy of orally administered antihistamines measured by positron emission tomography with 11C-doxepin in a placebo-controlled crossover study design in healthy subjects: a comparison of olopatadine and ketotifen

    PubMed Central

    Tashiro, Manabu; Mochizuki, Hideki; Sakurada, Yumiko; Ishii, Kenji; Oda, Keiichi; Kimura, Yuichi; Sasaki, Toru; Ishiwata, Kiichi; Yanai, Kazuhiko

    2006-01-01

    Aims The strength of sedation due to antihistamines can be evaluated by using positron emission tomography (PET). The purpose of the present study is to measure histamine H1 receptor (H1R) occupancy due to olopatadine, a new second-generation antihistamine and to compare it with that of ketotifen. Methods Eight healthy males (mean age 23.5 years-old) were studied following single oral administration of olopatadine 5 mg or ketotifen 1 mg using PET with 11C-doxepin in a placebo-controlled crossover study design. Binding potential ratio and H1R occupancy were calculated and were compared between olopatadine and ketotifen in the medial prefrontal (MPFC), dorsolateral prefrontal (DLPFC), anterior cingulate (ACC), insular (IC), temporal (TC), parietal (PC), occipital cortices (OC). Plasma drug concentration was measured, and correlation of AUC to H1R occupancy was examined. Results H1R occupancy after olopatadine treatment was significantly lower than that after ketotifen treatment in the all cortical regions (P < 0.001). Mean H1R occupancies for olopatadine and ketotifen were, respectively: MPFC, 16.7 vs. 77.7; DLPFC, 14.1 vs. 85.9; ACC, 14.7 vs. 76.1; IC, 12.8 vs. 69.7; TC, 12.5 vs. 66.5; PC, 13.9 vs. 65.8; and OC, 19.5 vs. 60.6. Overall cortical mean H1R occupancy of olopatadine and ketotifen were 15% and 72%, respectively. H1R occupancy of both drugs correlated well with their respective drug plasma concentrations (P < 0.001). Conclusion It is suggested that 5 mg oral olopatadine, with its low H1R occupancy and thus minimal sedation, could safely be used an antiallergic treatment for various allergic disorders. Abbreviations histamine H1 receptor (H1R), histamine H1 receptor occupancy (H1RO), dopamine D2 receptor (D2R), positron emission tomography (PET), blood–brain barrier (BBB), binding potential ratio (BPR), distribution volume (DV) PMID:16390347

  18. Dimensional crossover of nonrelativistic bosons

    NASA Astrophysics Data System (ADS)

    Lammers, Soeren; Boettcher, Igor; Wetterich, Christof

    2016-06-01

    We investigate how confining a transverse spatial dimension influences the few- and many-body properties of nonrelativistic bosons with pointlike interactions. Our main focus is on the dimensional crossover from three to two dimensions, which is of relevance for ultracold-atom experiments. Using functional-renormalization-group equations and T -matrix calculations we study how the phase transition temperature changes as a function of the spatial extent of the transverse dimension and relate the three- and two-dimensional s -wave scattering lengths. The analysis reveals how the properties of the lower-dimensional system are inherited from the higher-dimensional one during renormalization-group evolution. We limit the discussion to confinements in a potential well with periodic boundary conditions and argue why this qualitatively captures the physics of other compactifications such as transverse harmonic confinement as in cold-atom experiments.

  19. 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

  20. In situ measurements of water crossover through the membrane for direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Xu, C.; Zhao, T. S.

    We show analytically that the water-crossover flux through the membrane used for direct methanol fuel cells (DMFCs) can be in situ determined by measuring the water flow rate at the exit of the cathode flow field. This measurement method enables investigating the effects of various design and geometric parameters as well as operating conditions, such as properties of cathode gas diffusion layer (GDL), membrane thickness, cell current density, cell temperature, methanol solution concentration, oxygen flow rate, etc., on water crossover through the membrane in situ in a DMFC. Water crossover through the membrane is generally due to electro-osmotic drag, diffusion and back convection. The experimental data showed that diffusion dominated the total water-crossover flux at low current densities due to the high water concentration difference across the membrane. With the increase in current density, the water flux by diffusion decreased, but the flux by back convection increased. The corresponding net water-transport coefficient was also found to decrease with current density. The experimental results also showed that the use of a hydrophobic cathode GDL with a hydrophobic MPL could substantially reduce water crossover through the membrane, and thereby significantly increasing the limiting current as the result of the improved oxygen transport. It was found that the cell operating temperature, oxygen flow rate and membrane thickness all had significant influences on water crossover, but the influence of methanol concentration was negligibly small.

  1. 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

  2. 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.

  3. [East Syracuse-Minoa Schools Environmental Education Materials, Middle School Package, Middle School Crossover Units.

    ERIC Educational Resources Information Center

    East Syracuse - Minoa Central Schools, East Syracuse, NY.

    This interdisciplinary series of five environmental education units is designed for teacher use at the middle school level. The two crossover units are designed to span a period of six to eight weeks at the beginning of the eighth grade. Each unit is developed around several organizing ideas or concepts; objectives, activities and strategies,…

  4. 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…

  5. 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.

  6. Self-assembly of DNA double-double crossover complexes into high-density, doubly connected, planar structures.

    PubMed

    Reishus, Dustin; Shaw, Bilal; Brun, Yuriy; Chelyapov, Nickolas; Adleman, Leonard

    2005-12-21

    We designed a molecular complex, the double-double crossover, consisting of four DNA double helices connected by six reciprocal exchanges. Atomic force micrographs suggest that double-double crossover complexes self-assemble into high-density, doubly connected, two-dimensional, planar structures. Such structures may be suitable as substrates for the deposition of nanomaterials in the creation of high-density electrical and quantum devices. We speculate about a modified double-double crossover complex that might self-assemble into high-density, doubly connected, three-dimensional structures. PMID:16351073

  7. Crossover Pedagogy: The Collaborative Search for Meaning

    ERIC Educational Resources Information Center

    Nash, Robert J.

    2009-01-01

    This article describes the author's cross-pedagogical approach to co-teaching with student affairs colleagues. The central goal of this approach is to help students create meaning for their lives. The author also gives an account of an incident that occurred in one seminar and illustrates the benefits of a crossover approach.

  8. 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 ...

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. The joy of six: how to control your crossovers.

    PubMed

    Globus, Samuel T; Keeney, Scott

    2012-03-30

    Meiotic cells tightly regulate the number and distribution of crossovers to promote accurate chromosome segregation. Yokoo and colleagues uncover a metazoan-specific, cyclin-like protein that is crucial for crossover formation. They utilize this protein's unique properties to explore a remarkable example of biological numerology, whereby nearly every meiotic cell in C. elegans makes precisely six crossovers, one for each of its six chromosome pairs. PMID:22464316

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  16. Regulation of Spatial Selectivity by Crossover Inhibition

    PubMed Central

    Cafaro, Jon; Rieke, Fred

    2013-01-01

    Signals throughout the nervous system diverge into parallel excitatory and inhibitory pathways that later converge on downstream neurons to control their spike output. Converging excitatory and inhibitory synaptic inputs can exhibit a variety of temporal relationships. A common motif is feedforward inhibition, in which an increase (decrease) in excitatory input precedes a corresponding increase (decrease) in inhibitory input. The delay of inhibitory input relative to excitatory input originates from an extra synapse in the circuit shaping inhibitory input. Another common motif is push-pull or “crossover” inhibition, in which increases (decreases) in excitatory input occur together with decreases (increases) in inhibitory input. Primate On midget ganglion cells receive primarily feedforward inhibition and On parasol cells receive primarily crossover inhibition; this difference provides an opportunity to study how each motif shapes the light responses of cell types that play a key role in visual perception. For full-field stimuli, feedforward inhibition abbreviated and attenuated responses of On midget cells, while crossover inhibition, though plentiful, had surprisingly little impact on the responses of On parasol cells. Spatially structured stimuli, however, could cause excitatory and inhibitory inputs to On parasol cells to increase together, adopting a temporal relation very much like that for feedforward inhibition. In this case, inhibitory inputs substantially abbreviated a cell’s spike output. Thus inhibitory input shapes the temporal stimulus selectivity of both midget and parasol ganglion cells, but its impact on responses of parasol cells depends strongly on the spatial structure of the light inputs. PMID:23575830

  17. Crossover scaling for moments in multifractal systems

    NASA Astrophysics Data System (ADS)

    Alstrom, Preben; Hansen, Lars K.; Rasmussen, Dan R.

    1987-07-01

    Invoking the formalism known from second-order phase transitions and thermodynamics, we analyze the step structure obtained at transitions to chaos in dynamical systems or where Cantor sets evolve in general. As examples, we treat the skew tent map analytically and Arnold's sine map numerically, but the presented formalism employed for embedding dimension d=1 is readily extended to higher dimensions. We outline the scaling behavior for the counting, the measure, and higher moments. In particular, we consider the crossover exponent ν which enters the scaling functions and for the measure is related to the critical exponent β and fractal dimension D. We emphasize that the general presence of a multifractal structure results in a value of ν which depends on from which moment it is defined, and deduce the saturation value of ν in the high-moment limit. Also, we derive the connection to thermodynamical functions as pressure, entropy, and escape rate. Finally, we examine the scaling behavior of the moments and scaling relations for exponents when either a ``ghost'' field or noise is introduced as a conjugated field involving the critical exponents α, γ, and δ as well as the crossover exponent μ.

  18. 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).

  19. 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.

  20. 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.

  1. 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.

  2. Stress Crossover in Newlywed Marriage: A Longitudinal and Dyadic Perspective

    ERIC Educational Resources Information Center

    Neff, Lisa A.; Karney, Benjamin R.

    2007-01-01

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

  3. Broadband Via-Less Microwave Crossover Using Microstrip-CPW Transitions

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

    The front-to-back interface between microstrip and CPW (coplanar waveguide) typically requires complex fabrication or has high radiation loss. The microwave crossover typically requires a complex fabrication step. The prior art in microstrip-CPW transition requires a physical vias connection between the microstrip and CPW line on a separate layer. The via-less version of this transition was designed empirically and does not have a close form solution. The prior art of the micro wave crossover requires either additional substrate or wire bond as an air bridge to isolate two microwave lines at the crossing junction. The disadvantages are high radiation loss, no analytical solution to the problem, lengthy simulation time, and complex fabrication procedures to generate air bridges or via. The disadvantage of the prior crossover is a complex fabrication procedure, which also affects the device reliability and yield. This microstrip-CPW transition is visualized as two microstrip-slotline transitions combined in a way that the radiation from two slotlines cancels each other out. The invention is designed based on analytical methods; thus, it significantly reduces the development time. The crossover requires no extra layer to cross two microwave signals and has low radiation loss. The invention is simple to fabricate and design. It produces low radiation loss and can be designed with low insertion loss, with some tradeoff with signal isolation. The microstrip-CPW transition is used as an interface to connect between the device and the circuit outside the package. The via-less microwave crossover is used to allow two signals to cross without using an extra layer or fabrication processing step to enable this function. This design allows the solution to be determined entirely though analytical techniques. In addition, a planar via-less microwave crossover using this technique was proposed. The experimental results show that the proposed crossover at 5 GHz has a minimum

  4. First 3-Way Lunar Radio Phase Ranging and Doppler Experiment in Chang'E-3 Lander Mission

    NASA Astrophysics Data System (ADS)

    PING, J.; Meng, Q.; Tang, G.; Jian, N.; Wang, Z.; Li, W.; Chen, C.; Wang, M.; Wang, M.; Lu, Y.; Yu, Q.; Mao, Y.; Miao, C.; Lei, Y.; Shu, F.; Cao, J.

    2014-04-01

    Radio science experiments have been involved in all of the Chinese lunar missions with different research objectives. In Chang'E-3 landing mission, a 3-way open loop lunar radio phase ranging and Doppler technique was suggested and tested. This technique is modified and updated from early multi-channel oneway Doppler deep space tracking technique developed for Chinese Mars mission Yinghuo-1. In the 1st preliminary experiments, we obtained 1sps continuous phase ranging data before and after the successful landing period, with a resolution of 0.5 millimeter or better. This method, called Lunar Radio Phase Ranging (LRPR) can be a new space geodetic technique to measure the station position, earth tide and rotation, lunar orbit, tide and liberation, by means of independent observation, or to work together with Lunar Laser Ranging. Also, it can be used in future Mars mission.

  5. 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.

  6. Standard model cross-over on the lattice

    NASA Astrophysics Data System (ADS)

    D'Onofrio, Michela; Rummukainen, Kari

    2016-01-01

    With the physical Higgs mass the standard model symmetry restoration phase transition is a smooth cross-over. We study the thermodynamics of the cross-over using numerical lattice Monte Carlo simulations of an effective SU (2 )×U (1 ) gauge+Higgs theory, significantly improving on previously published results. We measure the Higgs field expectation value, thermodynamic quantities like pressure, energy density, speed of sound and heat capacity, and screening masses associated with the Higgs and Z fields. While the cross-over is smooth, it is very well defined with a width of only ˜5 GeV . We measure the cross-over temperature from the maximum of the susceptibility of the Higgs condensate, with the result Tc=159.5 ±1.5 GeV . Outside of the narrow cross-over region the perturbative results agree well with nonperturbative ones.

  7. 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

  8. 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.

  9. 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.

  10. 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. PMID:24313528

  11. 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.

  12. 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

  13. 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.

  14. Deformation mechanism crossover and mechanical behaviour in nanocrystalline materials.

    SciTech Connect

    Yamakov, V.; Wolf, D.; Phillpot, S. R.; Mukherjee, A. K.; Gleiter, H.; Materials Science Division; Univ. of California-Davis; Forschungszentrum Karlsruhe

    2003-06-01

    We use molecular dynamics simulations to elucidate the transition with decreasing grain size from a dislocation- to a grain-boundary-based deformation mechanism in nanocrystalline fcc metals. Our simulations reveal that this crossover is accompanied by a pronounced transition in the mechanical behaviour of the material; namely, at the grain size where the crossover occurs (the 'strongest size'), the strain rate under tensile elongation goes through a minimum. This simultaneous transition in both the deformation mechanism and the corresponding mechanical behaviour offers an explanation for the experimentally observed crossover in the yield strength of nanocrystalline materials, from Hall-Petch hardening to 'inverse Hall-Petch' softening.

  15. 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…

  16. 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…

  17. 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.

  18. Vortices and flux tubes: The crossover

    NASA Astrophysics Data System (ADS)

    Bracco, A.; Spiegel, E. A.

    2012-12-01

    The sun has magnetic flux tubes that cause sunspots by locally inhibiting convection near its surface. Jupiter has vortices that make the great red spot and other such blemishes. Why are there no similar vortices on the sun? How is the difference in the two kinds of system controlled by the magnetic Prandtl number? What happens at the crossover between the two behaviors? The transition between velocity and magnetically dominated regimes is the driving question of this work. It should occur somewhere in the enormous range in Prandtl number between the sun and planets like Jupiter. Objects that lie in between these vastly different extremes are Brown Dwarfs that have such low mass that they do not burn hydrogen in their cores. These objects are now being actively observed though there is as yet no direct evidence bearing on the present calculations. Other possibly interesting conditions may arise in certain disks around newborn stars where planetary systems are thought to be forming. These may be cool enough to place them in an interesting parameter range for the competition we describe. Using 2D calculations, we seek a quantitative measure of the relative importance of the two vector fields seen in the calculations, statistical or spectral, topological or structural.

  19. 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.

  20. Electrostatically-tuned dimensional crossover in nanowires

    NASA Astrophysics Data System (ADS)

    Tomczyk, Michelle; Cheng, Guanglei; Huang, Mengchen; Lee, Hyungwoo; Eom, Chang-Beom; Irvin, Patrick; Levy, Jeremy

    The electron system at the interface of two complex oxides, LaAlO3 and SrTiO3, exhibits a number of interesting strongly-correlated electronic properties, such as superconductivity and spin-orbit coupling. Reduced dimensionality is made accessible through nanowire devices created with conducting AFM lithography. Here, we describe an electrostatically-controlled dimensionality crossover in weak antilocalization behavior of LaAlO3/SrTiO3 nanowires at low temperature. These measurements give insight to the interplay of spin-orbit coupling and dimensionality. Characterizing the behavior of the strongly-correlated electronic properties in these reduced dimensions is necessary in order to develop this system as a multifunctional nanoelectronics platform. We gratefully acknowledge financial support from the following agencies and grants: ARO (W911NF-08-1-0317), AFOSR FA9550-10-1-0524 (JL) and FA9550-12-1-0342 (CBE), and NSF (DMR-1104191, DMR-1124131 (JL), ONR N00014-15-1-2847 (JL) and DMR-1234096 (CBE).

  1. 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.

  2. 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

  3. Hysteretic behavior of spin-crossover noise driven system

    NASA Astrophysics Data System (ADS)

    Gudyma, Iurii; Maksymov, Artur; Dimian, Mihai

    2016-04-01

    The influence of white Gaussian noise on hysteretic behavior of spin-crossover system is analyzed in the framework of stochastic Langevin dynamics. Various stochastic simulations are performed and several important properties of spin-transition in spin-crossover system driven by noise are reproduced. The numerical results are tested against the stationary probability function and the associated dynamic potential obtained from Fokker-Planck equation corresponding to spin-crossover Langevin dynamics. The dependence of light-induced optical hysteresis width and non-hysteretic transition curve slope on the noise intensity is illustrated. The role of low-spin and high-spin phase stabilities in the hysteretic behavior of noise-driven spin-crossover system is discussed.

  4. 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

  5. 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

  6. 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.

  7. 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

  8. 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

    2015-01-01

    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. PMID:26653857

  9. 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

  10. 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.

  11. The dynamical crossover in attractive colloidal systems

    NASA Astrophysics Data System (ADS)

    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.

  12. Transient regimes and crossover for epitaxial surfaces.

    PubMed

    Haselwandter, Christoph A; Vvedensky, Dimitri D

    2010-02-01

    We apply a formalism for deriving stochastic continuum equations associated with lattice models to obtain equations governing the transient regimes of epitaxial growth for various experimental scenarios and growth conditions. The first step of our methodology is the systematic transformation of the lattice model into a regularized stochastic equation of motion that provides initial conditions for differential renormalization-group (RG) equations for the coefficients in the regularized equation. The solutions of the RG equations then yield trajectories that describe the original model from the transient regimes, which are of primary experimental interest, to the eventual crossover to the asymptotically stable fixed point. We first consider regimes defined by the relative magnitude of deposition noise and diffusion noise. If the diffusion noise dominates, then the early stages of growth are described by the Mullins-Herring (MH) equation with conservative noise. This is the classic regime of molecular-beam epitaxy. If the diffusion and deposition noise are of comparable magnitude, the transient equation is the MH equation with nonconservative noise. This behavior has been observed in a recent report on the growth of aluminum on silicone oil surfaces [Z.-N. Fang, Thin Solid Films 517, 3408 (2009)]. Finally, the regime where deposition noise dominates over diffusion noise has been observed in computer simulations, but does not appear to have any direct experimental relevance. For initial conditions that consist of a flat surface, the Villain-Lai-Das Sarma (VLDS) equation with nonconservative noise is not appropriate for any transient regime. If, however, the initial surface is corrugated, the relative magnitudes of terms can be altered to the point where the VLDS equation with conservative noise does indeed describe transient growth. This is consistent with the experimental analysis of growth on patterned surfaces [H.-C. Kan, Phys. Rev. Lett. 92, 146101 (2004); T

  13. 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. PMID:24320386

  14. Electronic structure in the crossover regimes in lower dimensional structures

    NASA Astrophysics Data System (ADS)

    Batabyal, R.; Dev, B. N.

    2014-11-01

    Modern growth and fabrication techniques can produce lower dimensional structures in the crossover regimes. Such structures in the crossover regimes can provide tunability of various properties of materials. For example, a zero-dimensional (0-D) structure (quantum dot) evolving towards a 3-D structure (bulk) shows electronic structure, which is neither 0-D-like, nor 3-D-like in the dimensional crossover regime. Within the crossover regime the electronic density of states (DOS) at Fermi level (Ef) keeps on changing as the size of the system changes. DOS at Ef determines many properties of materials, such as electronic specific heat, spin susceptibility, etc. Such properties can be tuned by controlling the size of the system in the crossover regimes. Keeping the importance of DOS at Ef in mind, we determine their values and other details of electronic structure of lower dimensional structures, in the 0-D to 1-D, 1-D to 2-D, 2-D to 3-D, 0-D to 2-D, 0-D to 3-D and 1-D to 3-D crossover regimes, in a simple free electron model. We compare our results with analytical theory and experimental results, wherever available. We also present some results obtained by scanning tunneling spectroscopy measurements on Ag islands on Si(1 1 1) substrates evolving from a 0-D to a 2-D structure. This simple model is quite useful in understanding lower dimensional structures in the crossover regimes and, in general, in nanoscale science. Fabrication of such structures would provide control on materials properties.

  15. 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.

  16. 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.

  17. A Link between Meiotic Prophase Progression and Crossover Control

    PubMed Central

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

    2006-01-01

    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. PMID:16462941

  18. The first jamming crossover: geometric and mechanical features.

    PubMed

    Pica Ciamarra, Massimo; Sollich, Peter

    2013-03-28

    The jamming transition characterizes athermal systems of particles interacting via finite range repulsive potentials, and occurs on increasing the density when particles cannot avoid making contacts with those of their first coordination shell. We have recently shown [M. Pica Ciamarra and P. Sollich, e-print arXiv:1209.3334] that the same systems are also characterized by a series of jamming crossovers. These occur at higher volume fractions as particles are forced to make contact with those of subsequent coordination shells. At finite temperature, the crossovers give rise to dynamic and thermodynamic density anomalies, including a diffusivity anomaly and a negative thermal expansion coefficient. Density anomalies may therefore be related to structural changes occurring at the jamming crossovers. Here we elucidate these structural changes, investigating the evolution of the structure and of the mechanical properties of a jammed system as its volume fraction varies from the jamming transition to and beyond the first jamming crossover. We show that the first jamming crossover occurs at a well defined volume fraction, and that it induces a rearrangement of the force network causing a softening of the system. It also causes qualitative changes in the normal mode density of states and the spatial properties of the normal mode vectors. PMID:23556780

  19. The first jamming crossover: Geometric and mechanical features

    NASA Astrophysics Data System (ADS)

    Ciamarra, Massimo Pica; Sollich, Peter

    2013-03-01

    The jamming transition characterizes athermal systems of particles interacting via finite range repulsive potentials, and occurs on increasing the density when particles cannot avoid making contacts with those of their first coordination shell. We have recently shown [M. Pica Ciamarra and P. Sollich, e-print arXiv:1209.3334] that the same systems are also characterized by a series of jamming crossovers. These occur at higher volume fractions as particles are forced to make contact with those of subsequent coordination shells. At finite temperature, the crossovers give rise to dynamic and thermodynamic density anomalies, including a diffusivity anomaly and a negative thermal expansion coefficient. Density anomalies may therefore be related to structural changes occurring at the jamming crossovers. Here we elucidate these structural changes, investigating the evolution of the structure and of the mechanical properties of a jammed system as its volume fraction varies from the jamming transition to and beyond the first jamming crossover. We show that the first jamming crossover occurs at a well defined volume fraction, and that it induces a rearrangement of the force network causing a softening of the system. It also causes qualitative changes in the normal mode density of states and the spatial properties of the normal mode vectors.

  20. Crossover Analysis of CHANG'E-1 Laser Altimeter Data

    NASA Astrophysics Data System (ADS)

    Hu, W.; Yue, Z.; Di, K.

    2011-08-01

    This paper presents a preliminary result of crossover analysis and adjustment of Chang'E-1(CE-1) Laser Altimeter (LAM) data of the Moon for global and regional mapping applications. During the operation of Chang'E-1 from November 28, 2007 to December 4, 2008, the laser altimeter acquired 1400 orbital profiles with about 9.12 million altimetric points. In our experiment, we derived more than 1.38 million crossovers from 1395 ground tracks covering the entire lunar surface after eliminating outliers of orbits and altimetric points. A method of least-squares crossover adjustment with a series of basis functions of time (trigonometric functions and polynomials) is developed to reconcile the LAM data by minimizing the crossover residuals globally. The normal equations are very large but sparse; therefore they are stored and solved using sparse matrix technique. In a test area (0°N~60°N, 50°W~0°W), the crossover residuals are reduced from 62.1m to 32.8m, and the quality of the DEM generated from the adjusted LAM data is improved accordingly. We will optimize the method for the global adjustment to generate a high precision consistent global DEM, which can be used as absolute control for lunar mapping with orbital images.

  1. Hadron-quark crossover and hot neutron stars at birth

    NASA Astrophysics Data System (ADS)

    Masuda, Kota; Hatsuda, Tetsuo; Takatsuka, Tatsuyuki

    2016-02-01

    We construct a new isentropic equation of state (EOS) at finite temperature, "Rover," on the basis of the hadron-quark crossover at high density. By using the new EOS, we study the structure of hot neutron stars at birth with typical lepton fraction (Y_l=0.3-0.4) and typical entropy per baryon (hat {S}=1{-}2). Due to the gradual appearance of quark degrees of freedom at high density, the temperature T and the baryon density ρ at the center of hot neutron stars with hadron-quark crossover are found to be smaller than those without the crossover by a factor of two or more. Typical energy release due to the contraction of a hot neutron star to a cold neutron star with mass M=1.4 M_{⊙} is shown to be about 0.04 M_{⊙}, with a spin-up rate of about 14%.

  2. 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

  3. 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.

  4. Crossover from Ballistic to Diffusive Thermal Transport in Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Yamamoto, Takahiro; Konabe, Satoru; Shiomi, Junichiro; Maruyama, Shigeo

    2009-09-01

    We present a theoretical scheme that seamlessly handles the crossover from fully ballistic to diffusive thermal transport regimes and apply it to carbon nanotubes. At room temperature, micrometer-length nanotubes belong to the intermediate regime in which ballistic and diffusive phonons coexist. According to our scheme, the thermal conductance of these nanotubes exhibit anomalous nonlinear dependence of tube length due to this coexistence. This result is in excellent agreement with molecular-dynamics simulation results showing the nonlinear thermal conductance. Additionally, we clarify the mechanism of crossover in terms of the length-dependent characteristic frequency.

  5. 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

  6. Improvement of erectile function with Prelox: a randomized, double-blind, placebo-controlled, crossover trial.

    PubMed

    Stanislavov, R; Nikolova, V; Rohdewald, P

    2008-01-01

    In a randomly allocated, double-blind, placebo-controlled, crossover design, 50 patients with mild to moderate erectile dysfunction (ED) were treated for 1 month with placebo or a combination of L-arginine aspartate and Pycnogenol (Prelox). Patients reported sexual function from diaries. Testosterone levels and endothelial NO synthase (e-NOS) were monitored along with routine clinical chemistry. Intake of Pycnogenol for 1 month restored erectile function to normal. Intercourse frequency doubled. e-NOS in spermatozoa and testosterone levels in blood increased significantly. Cholesterol levels and blood pressure were lowered. No unwanted effects were reported. Prelox is a promising alternative to treat mild to moderate ED. PMID:17703218

  7. A case-crossover analysis of air pollution and mortality in Philadelphia.

    PubMed Central

    Neas, L M; Schwartz, J; Dockery, D

    1999-01-01

    This study reassessed Schwartz and Dockery's analysis of daily mortality from nonexternal causes among residents of Philadelphia, Pennsylvania, over 8 years, from 1973 to 1980 [American Review of Respiratory Disease 145:600-604 (1992)]. A Poisson regression analysis using the same model found that a 100-microg/m(3) increment in the 48-hr mean concentration of total suspended particulates (TSP) was associated with increased all-cause mortality [rate ratio = 1.069; 95% confidence interval (CI), 1.043-1.096) after adjustment for quadratic trend, season, year, previous day's mean temperature, dew point, winter temperature, and indicators of hot (temperature > 80 degrees F) and humid days (dew point > 66 degrees F). Critics suggested that time-varying factors such as season and day of week were not sufficiently controlled in this analysis and subsequent studies in other locations. We used a conditional logistic regression analysis with a case-crossover design to reanalyze the data, with air pollution in the prior and subsequent weeks to the day of death serving as referent periods. The case-crossover approach controls for season and day of week by design rather than modeling. We found that a 100-microg/m(3) increment in the 48-hr mean level of TSP was associated with increased all-cause mortality [odds ratio (OR) = 1.056; CI, 1.027-1.086) after adjustment for the same weather variables as above. Similar associations were observed for deaths in individuals over 65 years of age (OR = 1.074; CI, 1. 037-1.111) and for deaths due to cardiovascular disease (OR = 1.063; CI, 1.021-1.107). The current case-crossover analysis confirms the general conclusion of the previous Poisson regression analysis of an association of TSP with daily mortality in Philadelphia, Pennsylvania. PMID:10417359

  8. 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.

  9. 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

  10. 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

  11. Crossover dynamics at large metastability in gas-liquid nucleation.

    PubMed

    Santra, Mantu; Bagchi, Biman

    2011-03-01

    We have developed an alternate description of dynamics of nucleation in terms of an extended set of order parameters. The order parameters consist of an ordered set of kth largest clusters, ordered such that k= 1 is the largest cluster in the system, k= 2 is the second largest cluster, and so on. We have derived an analytic expression for the free energy for the kth largest cluster, which is in excellent agreement with the simulated results. At large supersaturation, the free energy barrier for the growth of the kth largest cluster disappears and the nucleation becomes barrierless. The major success of this extended theoretical formalism is that it can clearly explain the observed change in mechanism at large metastability [P. Bhimalapuram et al., Phys. Rev. Lett. 98, 206104 (2007)] and the associated dynamical crossover. The classical nucleation theory cannot explain this crossover. The crossover from activated to barrierless nucleation is found to occur at a supersaturation where multiple clusters cross the critical size. We attribute the crossover as the onset of the kinetic spinodal. We have derived an expression for the rate of nucleation in the barrierless regime by modeling growth as diffusion on the free energy surface of the largest cluster. The model reproduces the slower increase in the rate of growth as a function of supersaturation, as observed in experiments. PMID:21517508

  12. 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.

  13. 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...

  14. 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...

  15. 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...

  16. 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...

  17. 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...

  18. Crossover between work and home in dyadic partner relationships.

    PubMed

    Dikkers, Josje S E; Geurts, Sabine A E; Kinnunen, Ulla; Kompier, Michiel A J; Taris, Toon W

    2007-12-01

    This study aimed at providing insight into the processes underlying crossover between "work" and "home" in dyadic partner relationships. Specifically, we examined to what extent husbands' work demands (work load and overtime hours) and psychological health (fatigue and depressive symptoms) "cross over" to their wives' home demands (home load) and psychological health. These associations were investigated among three couple groups, based on wives' working hours (i.e., more than 20 hours per week, from 1 to 20 hours per week, and not engaged in paid work) (253 couples in total). All husbands worked for at least 35 hours a week. Three possible crossover mechanisms were hypothesized: (i) time-based, (ii) strain-based, and (iii) empathy-based crossover. The results partially supported mechanisms (i) and (ii): when husbands reported higher work load (mechanism i) and more psychological health complaints (mechanism ii), their wives experienced higher home load. The results further supported mechanism (iii) that wives' and husbands' psychological health were associated. It is concluded that crossover from husbands to wives may occur through various mechanisms. PMID:18028075

  19. 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.…

  20. Academic Crossover Study, University of Hawaii Community Colleges, Fall 1999.

    ERIC Educational Resources Information Center

    Hawaii Univ., Honolulu. Office of the Chancellor for Community Colleges.

    The academic crossover study was developed to answer two questions: (1) What is the course-taking pattern of the different groups of academic majors? (e.g. what is proportion of academic load taken outside the major); and (2) What is the client-serving pattern of the different subject disciplines? (e.g. what are the groups of students served by…

  1. Size-dependent dielectrophoretic crossover frequency of spherical particles.

    PubMed

    Weng, Ping-You; Chen, I-An; Yeh, Che-Kai; Chen, Pin-Yi; Juang, Jia-Yang

    2016-01-01

    Dielectrophoresis (DEP) has been extensively used in lab-on-a-chip systems for trapping, separating, and manipulating of micro particles suspended in a liquid medium. The most widely used analytic model, the dipole model, provides an accurate prediction on the crossover frequency of submicron particles, but cannot explain the significant drop in crossover frequency of larger particles. Here, we present numerical simulations using the Maxwell stress tensor (MST) and finite element method to study the size effect of the DEP crossover frequency of spherical polystyrene particles suspended in de-ionized water. Our results show that the surface conductance due to the electrical double layer plays a key role, and the size dependency of crossover frequency obtained by the MST method agrees reasonably well with published experimental data. The exponents of the power law are approximately -1.0 and -4.3 for smaller (diameter < 4.6 μm) and larger particles (diameter  > 4.6 μm), respectively. The free surface charge distribution reveals that the charge begins accumulating on the particle equator for particle diameters larger than a critical diameter of 4.6 μm, a result not captured by the dipolar approximation. This method may be extended to analyze bioparticles with complex shapes and composition, and provides new insights into the interpretation of dielectrophoresis applications using lab-on-a-chip systems. PMID:26909121

  2. Ergodic crossover in partially self-avoiding stochastic walks

    NASA Astrophysics Data System (ADS)

    Berbert, Juliana M.; González, Rodrigo Silva; Martinez, Alexandre Souto

    2013-09-01

    Consider a one-dimensional environment with N randomly distributed sites. An agent explores this random medium moving deterministically with a spatial memory μ. A crossover from local to global exploration occurs in one dimension at a well-defined memory value μ1=log2N. In its stochastic version, the dynamics is ruled by the memory and by temperature T, which affects the hopping displacement. This dynamics also shows a crossover in one dimension, obtained computationally, between exploration schemes, characterized yet by the trajectory size (Np) (aging effect). In this paper we provide an analytical approach considering the modified stochastic version where the parameter T plays the role of a maximum hopping distance. This modification allows us to obtain a general analytical expression for the crossover, as a function of the parameters μ, T, and Np. Differently from what has been proposed by previous studies, we find that the crossover occurs in any dimension d. These results have been validated by numerical experiments and may be of great value for fixing optimal parameters in search algorithms.

  3. Ergodic crossover in partially self-avoiding stochastic walks.

    PubMed

    Berbert, Juliana M; González, Rodrigo Silva; Martinez, Alexandre Souto

    2013-09-01

    Consider a one-dimensional environment with N randomly distributed sites. An agent explores this random medium moving deterministically with a spatial memory μ. A crossover from local to global exploration occurs in one dimension at a well-defined memory value μ_{1}=log_{2}N. In its stochastic version, the dynamics is ruled by the memory and by temperature T, which affects the hopping displacement. This dynamics also shows a crossover in one dimension, obtained computationally, between exploration schemes, characterized yet by the trajectory size (N_{p}) (aging effect). In this paper we provide an analytical approach considering the modified stochastic version where the parameter T plays the role of a maximum hopping distance. This modification allows us to obtain a general analytical expression for the crossover, as a function of the parameters μ, T, and N_{p}. Differently from what has been proposed by previous studies, we find that the crossover occurs in any dimension d. These results have been validated by numerical experiments and may be of great value for fixing optimal parameters in search algorithms. PMID:24125225

  4. 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

  5. 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

  6. 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

  7. 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…

  8. 49 CFR 236.203 - Hand operated crossover between main tracks; protection.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Hand operated crossover between main tracks..., AND APPLIANCES Automatic Block Signal Systems Standards § 236.203 Hand operated crossover between main tracks; protection. At hand-operated crossover between main tracks, protection shall be provided by...

  9. 49 CFR 236.203 - Hand operated crossover between main tracks; protection.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Hand operated crossover between main tracks..., AND APPLIANCES Automatic Block Signal Systems Standards § 236.203 Hand operated crossover between main tracks; protection. At hand-operated crossover between main tracks, protection shall be provided by...

  10. 49 CFR 236.203 - Hand operated crossover between main tracks; protection.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Hand operated crossover between main tracks..., AND APPLIANCES Automatic Block Signal Systems Standards § 236.203 Hand operated crossover between main tracks; protection. At hand-operated crossover between main tracks, protection shall be provided by...

  11. 49 CFR 236.203 - Hand operated crossover between main tracks; protection.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Hand operated crossover between main tracks..., AND APPLIANCES Automatic Block Signal Systems Standards § 236.203 Hand operated crossover between main tracks; protection. At hand-operated crossover between main tracks, protection shall be provided by...

  12. 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

  13. 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

  14. 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

  15. 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

  16. 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.

  17. 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

  18. 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…

  19. 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…

  20. 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:…

  1. 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. PMID:26972026

  2. A Case-Crossover Study of Sleep and Work Hours and the Risk of Road Traffic Accidents

    PubMed Central

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

    2010-01-01

    Study Objectives: Sleepiness, prolonged wakefulness, and extended work hours have been associated with increased risk of injuries and road accidents. The authors' objective was to study the relation between those factors and road accidents using a case-crossover design, effective in estimating the risk of acute events associated with transient, short effect exposures. Design: Five hundred seventy-four injured drivers presenting for care after road accidents to the Emergency Room of Udine, Italy, were enrolled in the study from March 2007 to March 2008. Sleep, work, and driving patterns in the 48 h before the accident were assessed through an interview. Measurements and Results: The relative risk (RR) of accident associated with each exposure was estimated using the case-crossover matched pair interval approach. Sleeping ≥ 11 h daily was associated with a decrease of the RR, as was sleeping less than usual. Being awake ≥ 16 h and, possibly, working > 12 h daily were associated with increases in the RR. Conclusions: Extended work hours and prolonged wakefulness increase the risk of road accidents and suggest that awareness should be raised among drivers. The findings regarding acute sleep amount are less clear, possibly due to an effect of chronic sleep loss. Citation: Valent F; Di Bartolomeo S; Marchetti R; Sbrojavacca R; Barbone F. A case-crossover study of sleep and work hours and the risk of road traffic accidents. SLEEP 2010;33(3):349-354. PMID:20337193

  3. Meiotic recombination and the crossover assurance checkpoint in Caenorhabditis elegans.

    PubMed

    Yu, Zhouliang; Kim, Yumi; Dernburg, Abby F

    2016-06-01

    During meiotic prophase, chromosomes pair and synapse with their homologs and undergo programmed DNA double-strand break (DSB) formation to initiate meiotic recombination. These DSBs are processed to generate a limited number of crossover recombination products on each chromosome, which are essential to ensure faithful segregation of homologous chromosomes. The nematode Caenorhabditis elegans has served as an excellent model organism to investigate the mechanisms that drive and coordinate these chromosome dynamics during meiosis. Here we focus on our current understanding of the regulation of DSB induction in C. elegans. We also review evidence that feedback regulation of crossover formation prolongs the early stages of meiotic prophase, and discuss evidence that this can alter the recombination pattern, most likely by shifting the genome-wide distribution of DSBs. PMID:27013114

  4. Stress-Based Crossover Operator for Structural Topology Optimization

    NASA Astrophysics Data System (ADS)

    Li, Cuimin; Hiroyasu, Tomoyuki; Miki, Mitsunori

    In this paper, we propose a stress-based crossover (SX) operator to solve the checkerboard-like material distributation and disconnected topology that is common for simple genetic algorithm (SGA) to structural topology optimization problems (STOPs). A penalty function is defined to evaluate the fitness of each individual. A number of constrained problems are adopted to experiment the effectiveness of SX for STOPs. Comparison of 2-point crossover (2X) with SX indicates that SX can markedly suppress the checkerboard-like material distribution phenomena. Comparison of evolutionary structural optimization (ESO) and SX demonstrates the global search ability and flexibility of SX. Experiments of a Michell-type problem verifies the effectiveness of SX for STOPs. For a multi-loaded problem, SX searches out alternate solutions on the same parameters that shows the global search ability of GA.

  5. Strategy Uniform Crossover Adaptation Evolution in a Minority Game

    NASA Astrophysics Data System (ADS)

    Yang, Wei-Song; Wang, Bing-Hong; Quan, Hong-Jun; Hu, Chin-Kun

    2003-10-01

    We propose and study a new adaptation minority game for understanding of the complex dynamical behaviour characterized by agent interactions competing limited resource in many natural and social systems. Intelligent agents may modify a part of strategies held by them periodically, depending on the strategy performances. In the new model, the strategies will be updated according to uniform-crossover variation process inspired by genetic evolution algorithm in biology. The performances of the agents in the new model are calculated for different parameter conditions. It has been found that the new system may evolve via the strategy uniform crossover adaptation mechanism into a frozen equilibrium state in which the performance of the system may reach the best limit, implying the strongest cooperation among agents and the most effective utilization of the social resources.

  6. 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.

  7. BCS to Bose crossover: Broken-symmetry state

    SciTech Connect

    Engelbrecht, J.R. |; Randeria, M. |; Sa de Melo, C.A.

    1997-06-01

    A functional integral formulation, used previously to calculate T{sub c} and describe normal state properties of the BCS-Bose crossover, is extended to T{lt}T{sub c}. The saddle point approximation is shown to be qualitatively correct for T{lt}T{sub c} for {ital all} couplings, in contrast to the situation above T{sub c}. Several features of the crossover are described. The difference between the T=0 {open_quotes}pair size{close_quotes} and the (prefactor of the T dependent) Ginzburg-Landau coherence length is pointed out: the two quantities are the same only in the BCS limit. The evolution of the collective modes from the BCS to the Bose regime is discussed together with the mixing of the amplitude and phase in the absence of a particle-hole symmetry. {copyright} {ital 1997} {ital The American Physical Society}

  8. 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.

  9. 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.

  10. Crossover from percolation to self-organized criticality

    NASA Astrophysics Data System (ADS)

    Drossel, Barbara; Clar, Siegfried; Schwabl, Franz

    1994-10-01

    We include immunity against fire into the self-organized critical forest-fire model. When the immunity assumes a critical value, clusters of burnt trees are identical to percolation clusters of random bond percolation. As long as the immunity is below its critical value, the asymptotic critical exponents are those of the original self-organized critical model, i.e., the system performs a crossover from percolation to self-organized criticality. We present a scaling theory and computer simulation results.

  11. 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.

  12. Nanoparticles of iron(II) spin-crossover.

    PubMed

    Forestier, Thibaut; Mornet, Stéphane; Daro, Nathalie; Nishihara, Taishi; Mouri, Shin-ichiro; Tanaka, Koichiro; Fouché, Olivier; Freysz, Eric; Létard, Jean-François

    2008-09-28

    We report the synthesis of spin crossover 69 nm spherical nanoparticles of [Fe(NH2-trz)3](Br)2.3H2O.0.03(surfactant) (NH2trz = 4-amino-1,2,4-triazole, surfactant = Lauropal), prepared by the reverse micelle technique, which exhibit at room temperature a thermal hysteresis characterized by magnetic, diffuse reflectivity and Raman studies. PMID:18802559

  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. A semi-parametric approach to the frequency of occurrence under a simple crossover trial.

    PubMed

    Lui, Kung-Jong; Chang, Kuang-Chao

    2016-02-01

    To analyze the frequency of occurrence for an event of interest in a crossover design, we propose a semi-parametric approach. We develop two point estimators and four interval estimators in closed forms for the treatment effect under a random effects multiplicative risk model. Using Monte Carlo simulations, we evaluate these estimators and compare the four interval estimators with the classical interval estimator suggested elsewhere in a variety of situations. We note that the point estimator using the ratio of two arithmetic averages of mean frequencies under a multiplicative risk model can be comparable to the point estimator using the ratio of two geometric averages of mean frequencies. We note that as long as the number of patients per group is large, all the four interval estimators developed here can perform well. We also note that the classical interval estimator derived under the commonly assumed Poisson distribution for the frequency data can be conservative and lose precision if the Poisson distribution assumption is violated. We use a double-blind randomized crossover trial comparing salmeterol with a placebo in exacerbations of asthma to illustrate the practical use of these estimators. PMID:22368177

  15. Enhanced nonlinear optical characteristics of copper-ion-doped double crossover DNAs

    NASA Astrophysics Data System (ADS)

    Park, Byeongho; Lee, Byung Jic; Dugasani, Sreekantha Reddy; Cho, Youngho; Kim, Chulki; Seo, Minah; Lee, Taikjin; Jhon, Young Min; Choi, Jaebin; Lee, Seok; Park, Sung Ha; Jun, Seong Chan; Yeom, Dong-Il; Rotermund, Fabian; Kim, Jae Hun

    2015-10-01

    The modification of deoxyribonucleic acid (DNA) samples by sequencing the order of bases and doping copper ions opens the possibility for the design of novel nanomaterials exhibiting large optical nonlinearity. We investigated the nonlinear characteristics of copper-ion doped double crossover DNA samples for the first time to the best of our knowledge by using Z-scan and four-wave mixing methods. To accelerate the nonlinear characteristics, we prepared two types of unique DNA nanostructures composed of 148 base pairs doped with copper ions with a facile annealing method. The outstanding third-order nonlinear optical susceptibility of the copper-ion-doped DNA solution, 1.19 × 10-12 esu, was estimated by the conventional Z-scan measurement, whereas the four-wave mixing experiment was also investigated. In the visible spectral range, the copper-ion-doped DNA solution samples provided competent four-wave mixing signals with a remarkable conversion efficiency of -4.15 dB for the converted signal at 627 nm. The interactions between DNA and copper ions contribute to the enhancement of nonlinearity due to structural and functional changes. The present study signifies that the copper-ion-doped double crossover DNA is a potential candidate as a highly efficient novel material for further nonlinear optical applications.

  16. Pressure and Temperature Spin Crossover Sensors with Optical Detection

    PubMed Central

    Linares, Jorge; Codjovi, Epiphane; Garcia, Yann

    2012-01-01

    Iron(II) spin crossover molecular materials are made of coordination centres switchable between two states by temperature, pressure or a visible light irradiation. The relevant macroscopic parameter which monitors the magnetic state of a given solid is the high-spin (HS) fraction denoted nHS, i.e., the relative population of HS molecules. Each spin crossover material is distinguished by a transition temperature T1/2 where 50% of active molecules have switched to the low-spin (LS) state. In strongly interacting systems, the thermal spin switching occurs abruptly at T1/2. Applying pressure induces a shift from HS to LS states, which is the direct consequence of the lower volume for the LS molecule. Each material has thus a well defined pressure value P1/2. In both cases the spin state change is easily detectable by optical means thanks to a thermo/piezochromic effect that is often encountered in these materials. In this contribution, we discuss potential use of spin crossover molecular materials as temperature and pressure sensors with optical detection. The ones presenting smooth transitions behaviour, which have not been seriously considered for any application, are spotlighted as potential sensors which should stimulate a large interest on this well investigated class of materials. PMID:22666041

  17. 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.

  18. 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.

  19. 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

  20. 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%.

  1. Fine Scale Analysis of Crossover and Non-Crossover and Detection of Recombination Sequence Motifs in the Honeybee (Apis mellifera)

    PubMed Central

    Bessoltane, Nadia; Toffano-Nioche, Claire; Solignac, Michel; Mougel, Florence

    2012-01-01

    Background Meiotic exchanges are non-uniformly distributed across the genome of most studied organisms. This uneven distribution suggests that recombination is initiated by specific signals and/or regulations. Some of these signals were recently identified in humans and mice. However, it is unclear whether or not sequence signals are also involved in chromosomal recombination of insects. Methodology We analyzed recombination frequencies in the honeybee, in which genome sequencing provided a large amount of SNPs spread over the entire set of chromosomes. As the genome sequences were obtained from a pool of haploid males, which were the progeny of a single queen, an oocyte method (study of recombination on haploid males that develop from unfertilized eggs and hence are the direct reflect of female gametes haplotypes) was developed to detect recombined pairs of SNP sites. Sequences were further compared between recombinant and non-recombinant fragments to detect recombination-specific motifs. Conclusions Recombination events between adjacent SNP sites were detected at an average distance of 92 bp and revealed the existence of high rates of recombination events. This study also shows the presence of conversion without crossover (i. e. non-crossover) events, the number of which largely outnumbers that of crossover events. Furthermore the comparison of sequences that have undergone recombination with sequences that have not, led to the discovery of sequence motifs (CGCA, GCCGC, CCGCA), which may correspond to recombination signals. PMID:22567142

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

    PubMed

    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. 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

  4. Assessing the Short-Term Effects of Heatwaves on Mortality and Morbidity in Brisbane, Australia: Comparison of Case-Crossover and Time Series Analyses

    PubMed Central

    Tong, Shilu; Wang, Xiao Yu; Guo, Yuming

    2012-01-01

    Background Heat-related impacts may have greater public health implications as climate change continues. It is important to appropriately characterize the relationship between heatwave and health outcomes. However, it is unclear whether a case-crossover design can be effectively used to assess the event- or episode-related health effects. This study examined the association between exposure to heatwaves and mortality and emergency hospital admissions (EHAs) from non-external causes in Brisbane, Australia, using both case-crossover and time series analyses approaches. Methods Poisson generalised additive model (GAM) and time-stratified case-crossover analyses were used to assess the short-term impact of heatwaves on mortality and EHAs. Heatwaves exhibited a significant impact on mortality and EHAs after adjusting for air pollution, day of the week, and season. Results For time-stratified case-crossover analysis, odds ratios of mortality and EHAs during heatwaves were 1.62 (95% confidence interval (CI): 1.36–1.94) and 1.22 (95% CI: 1.14–1.30) at lag 1, respectively. Time series GAM models gave similar results. Relative risks of mortality and EHAs ranged from 1.72 (95% CI: 1.40–2.11) to 1.81 (95% CI: 1.56–2.10) and from 1.14 (95% CI: 1.06–1.23) to 1.28 (95% CI: 1.21–1.36) at lag 1, respectively. The risk estimates gradually attenuated after the lag of one day for both case-crossover and time series analyses. Conclusions The risk estimates from both case-crossover and time series models were consistent and comparable. This finding may have implications for future research on the assessment of event- or episode-related (e.g., heatwave) health effects. PMID:22655052

  5. Molecular Mechanisms of Spin Crossover in the {Fe(pz)[Pt(CN)4]} Metal-Organic Framework upon Water Adsorption.

    PubMed

    Pham, C Huy; Cirera, Jordi; Paesani, Francesco

    2016-05-18

    The rational design of multifunctional materials with properties that can be selectively controlled at the molecular level is key to the development and application of nanoscale devices. In this study, molecular dynamics simulations using ligand-field molecular mechanics are performed to elucidate, for the first time, the molecular mechanisms responsible for the variation of the spin-crossover properties of the {Fe(pz)[Pt(CN)4]} metal-organic framework upon water adsorption. The simulations demonstrate a direct relationship between the water loading adsorbed in the pores and the variation of the spin-crossover transition temperature, with the high-spin state of the material becoming gradually more stabilized as the number of adsorbed water molecules increases. The decrease of the spin-crossover temperature of {Fe(pz)[Pt(CN)4]} upon water adsorption predicted by the simulations is in agreement with the available experimental data and is traced back to the elongation of the bonds between the Fe(II) atoms and the organic linkers induced by interactions of the adsorbed water molecules with the framework. PMID:27149014

  6. 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

  7. Crossover of marital dissatisfaction during military downsizing among Russian army officers and their spouses.

    PubMed

    Westman, Mina; Vinokur, Amiram D; Hamilton, V Lee; Roziner, Ilan

    2004-10-01

    This study examined mechanisms of strain crossover within couples and the moderating role of gender. Data were collected at a time of military downsizing from a sample of 1,250 Russian army officers and their spouses. The authors tested a model that incorporated 3 mechanisms for the crossover of marital dissatisfaction among dual-earner couples. The model provided support for 2 suggested crossover mechanisms: direct reactions of crossover and indirect mediated effects through social undermining. Strong evidence was also provided for gender asymmetry in the crossover process. Marital dissatisfaction crossed over from husbands to wives but not vice versa, and social undermining behavior played a role in the process of crossover of marital dissatisfaction for husbands but not for wives. PMID:15506859

  8. 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.

  9. 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

  10. Logical computation using algorithmic self-assembly of DNA triple-crossover molecules

    NASA Astrophysics Data System (ADS)

    Mao, Chengde; LaBean, Thomas H.; Reif, John H.; Seeman, Nadrian C.

    2000-09-01

    Recent work has demonstrated the self-assembly of designed periodic two-dimensional arrays composed of DNA tiles, in which the intermolecular contacts are directed by `sticky' ends. In a mathematical context, aperiodic mosaics may be formed by the self-assembly of `Wang' tiles, a process that emulates the operation of a Turing machine. Macroscopic self-assembly has been used to perform computations; there is also a logical equivalence between DNA sticky ends and Wang tile edges. This suggests that the self-assembly of DNA-based tiles could be used to perform DNA-based computation. Algorithmic aperiodic self-assembly requires greater fidelity than periodic self-assembly, because correct tiles must compete with partially correct tiles. Here we report a one-dimensional algorithmic self-assembly of DNA triple-crossover molecules that can be used to execute four steps of a logical (cumulative XOR) operation on a string of binary bits.

  11. Flunarizine as add-on therapy in epilepsy. Crossover study vs placebo.

    PubMed

    Moglia, A; Bergamasco, B; Di Perri, R; Mancia, D

    1986-01-01

    The anticonvulsive effect of flunarizine was studied in a multicenter trial, by means of a randomized, double-blind, single crossover design. The subjects who entered the study were 51 males and 39 females, aged 15 to 73 years. They were epileptic patients who suffered from at least two generalized seizures per month or more than 4 partial seizures per month. The patients were already being treated with major antiepileptic drugs. Flunarizine was administered in a single evening dose of 10 mg/die in patients who weighed less than 70 kg and of 15 mg/die in patients who weighed more 70 kg. Our results show that flunarizine, given as add-on therapy, produced a slight but significant decrease in the number of monthly seizures at the end of a 3-month period, while placebo did not significantly change the seizures frequency. PMID:3301560

  12. Dynamic Chemistry of Disulfide Terminated Oligonucleotides in Duplexes and Double-Crossover Tiles.

    PubMed

    De Stefano, Mattia; Vesterager Gothelf, Kurt

    2016-06-16

    Designed nanostructures formed by self-assembly of multiple DNA strands suffer from low stability at elevated temperature and under other denaturing conditions. Here, we propose a method for covalent coupling of DNA strands in such structures by the formation of disulfide bonds; this allows disassembly of the structure under reducing conditions. The dynamic chemistry of disulfides and thiols was applied to crosslink DNA strands with terminal disulfide modifications. The formation of disulfide-linked DNA duplexes consisting of three strands is demonstrated, as well as a more-complex DNA double-crossover tile. All the strands in the fully disulfide-linked structures are covalently and geometrically interlocked, and it is demonstrated that the structures are stable under heating and in the presence of denaturants. Such a reversible system can be exploited in applications where higher DNA stability is needed only temporarily, such as delivery of cargoes to cells by DNA nanostructures. PMID:26994867

  13. 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.

  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. Crossover from superdiffusive to diffusive dynamics in fluctuating light fields

    NASA Astrophysics Data System (ADS)

    Marqués, Manuel I.

    2016-06-01

    The expressions for the optical drag force, the equilibrium kinetic energy, and the diffusion constant of an electric dipole in a light field consisting of electromagnetic plane waves with polarizations randomly distributed and fluctuating phases are obtained. The drag force is proportional to the extinction cross section of the dipole and to the intensity. The diffusion constant does not depend on the amplitude of the electromagnetic field and is proportional to the time interval between fluctuations. Numerical simulations for the dynamics of a resonant dipole, initially at rest, show the crossover between the superdiffusive and the diffusive regimes theoretically predicted.

  16. 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

  17. Hot Regions of Noninterfering Crossovers Coexist with a Nonuniformly Interfering Pathway in Arabidopsis thaliana

    PubMed Central

    Basu-Roy, Sayantani; Gauthier, Franck; Giraut, Laurène; Mézard, Christine; Falque, Matthieu; Martin, Olivier C.

    2013-01-01

    In most organisms that have been studied, crossovers formed during meiosis exhibit interference: nearby crossovers are rare. Here we provide an in-depth study of crossover interference in Arabidopsis thaliana, examining crossovers genome-wide in >1500 backcrosses for both male and female meiosis. This unique data set allows us to take a two-pathway modeling approach based on superposing a fraction p of noninterfering crossovers and a fraction (1 − p) of interfering crossovers generated using the gamma model characterized by its interference strength nu. Within this framework, we fit the two-pathway model to the data and compare crossover interference strength between chromosomes and then along chromosomes. We find that the interfering pathway has markedly higher interference strength nu in female than in male meiosis and also that male meiosis has a higher proportion p of noninterfering crossovers. Furthermore, we test for possible intrachromosomal variations of nu and p. Our conclusion is that there are clear differences between left and right arms as well as between central and peripheral regions. Finally, statistical tests unveil a genome-wide picture of small-scale heterogeneities, pointing to the existence of hot regions in the genome where crossovers form preferentially without interference. PMID:24026099

  18. 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

  19. An alternative approach for neural network evolution with a genetic algorithm: crossover by combinatorial optimization.

    PubMed

    García-Pedrajas, Nicolás; Ortiz-Boyer, Domingo; Hervás-Martínez, César

    2006-05-01

    In this work we present a new approach to crossover operator in the genetic evolution of neural networks. The most widely used evolutionary computation paradigm for neural network evolution is evolutionary programming. This paradigm is usually preferred due to the problems caused by the application of crossover to neural network evolution. However, crossover is the most innovative operator within the field of evolutionary computation. One of the most notorious problems with the application of crossover to neural networks is known as the permutation problem. This problem occurs due to the fact that the same network can be represented in a genetic coding by many different codifications. Our approach modifies the standard crossover operator taking into account the special features of the individuals to be mated. We present a new model for mating individuals that considers the structure of the hidden layer and redefines the crossover operator. As each hidden node represents a non-linear projection of the input variables, we approach the crossover as a problem on combinatorial optimization. We can formulate the problem as the extraction of a subset of near-optimal projections to create the hidden layer of the new network. This new approach is compared to a classical crossover in 25 real-world problems with an excellent performance. Moreover, the networks obtained are much smaller than those obtained with classical crossover operator. PMID:16343847

  20. Randomized controlled crossover trial of ketamine in obsessive-compulsive disorder: proof-of-concept.

    PubMed

    Rodriguez, Carolyn I; Kegeles, Lawrence S; Levinson, Amanda; Feng, Tianshu; Marcus, Sue M; Vermes, Donna; Flood, Pamela; Simpson, Helen B

    2013-11-01

    Serotonin reuptake inhibitors (SRIs), the first-line pharmacological treatment for obsessive-compulsive disorder (OCD), have two limitations: incomplete symptom relief and 2-3 months lag time before clinically meaningful improvement. New medications with faster onset are needed. As converging evidence suggests a role for the glutamate system in the pathophysiology of OCD, we tested whether a single dose of ketamine, a non-competitive N-methyl-D-aspartate (NMDA) glutamate receptor antagonist, could achieve rapid anti-obsessional effects. In a randomized, double-blind, placebo-controlled, crossover design, drug-free OCD adults (n=15) with near-constant obsessions received two 40-min intravenous infusions, one of saline and one of ketamine (0.5 mg/kg), spaced at least 1-week apart. The OCD visual analog scale (OCD-VAS) and the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) were used to assess OCD symptoms. Unexpectedly, ketamine's effects within the crossover design showed significant (p<0.005) carryover effects (ie, lasting longer than 1 week). As a result, only the first-phase data were used in additional analyses. Specifically, those receiving ketamine (n=8) reported significant improvement in obsessions (measured by OCD-VAS) during the infusion compared with subjects receiving placebo (n=7). One-week post-infusion, 50% of those receiving ketamine (n=8) met criteria for treatment response (≥35% Y-BOCS reduction) vs 0% of those receiving placebo (n=7). Rapid anti-OCD effects from a single intravenous dose of ketamine can persist for at least 1 week in some OCD patients with constant intrusive thoughts. This is the first randomized, controlled trial to demonstrate that a drug affecting glutamate neurotransmission can reduce OCD symptoms without the presence of an SRI and is consistent with a glutamatergic hypothesis of OCD. PMID:23783065

  1. Randomized Controlled Crossover Trial of Ketamine in Obsessive-Compulsive Disorder: Proof-of-Concept

    PubMed Central

    Rodriguez, Carolyn I; Kegeles, Lawrence S; Levinson, Amanda; Feng, Tianshu; Marcus, Sue M; Vermes, Donna; Flood, Pamela; Simpson, Helen B

    2013-01-01

    Serotonin reuptake inhibitors (SRIs), the first-line pharmacological treatment for obsessive-compulsive disorder (OCD), have two limitations: incomplete symptom relief and 2–3 months lag time before clinically meaningful improvement. New medications with faster onset are needed. As converging evidence suggests a role for the glutamate system in the pathophysiology of OCD, we tested whether a single dose of ketamine, a non-competitive N-methyl-D-aspartate (NMDA) glutamate receptor antagonist, could achieve rapid anti-obsessional effects. In a randomized, double-blind, placebo-controlled, crossover design, drug-free OCD adults (n=15) with near-constant obsessions received two 40-min intravenous infusions, one of saline and one of ketamine (0.5 mg/kg), spaced at least 1-week apart. The OCD visual analog scale (OCD-VAS) and the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) were used to assess OCD symptoms. Unexpectedly, ketamine's effects within the crossover design showed significant (p<0.005) carryover effects (ie, lasting longer than 1 week). As a result, only the first-phase data were used in additional analyses. Specifically, those receiving ketamine (n=8) reported significant improvement in obsessions (measured by OCD-VAS) during the infusion compared with subjects receiving placebo (n=7). One-week post-infusion, 50% of those receiving ketamine (n=8) met criteria for treatment response (⩾35% Y-BOCS reduction) vs 0% of those receiving placebo (n=7). Rapid anti-OCD effects from a single intravenous dose of ketamine can persist for at least 1 week in some OCD patients with constant intrusive thoughts. This is the first randomized, controlled trial to demonstrate that a drug affecting glutamate neurotransmission can reduce OCD symptoms without the presence of an SRI and is consistent with a glutamatergic hypothesis of OCD. PMID:23783065

  2. 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

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

    PubMed

    Smeds, Linnéa; Mugal, Carina F; Qvarnström, Anna; Ellegren, Hans

    2016-05-01

    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

  4. Instructional Design Paradigms: Is Object-Oriented Design Next?

    ERIC Educational Resources Information Center

    Ross, John Minor

    1996-01-01

    Proposes that object-oriented (OO) analysis, design, and programming methods, currently having a major impact on computing, will play an increasing role in shaping the paradigms of performance technology--particularly in instructional design (ID). Ties this crossover of OO from computing to ID to design trends and ongoing research in ID. (AEF)

  5. Superconductor-Insulator Transition and Fermi-Bose Crossovers

    NASA Astrophysics Data System (ADS)

    Trivedi, Nandini; Loh, Yen Lee; Randeria, Mohit; Chang, Chia-Chen; Scalettar, Richard

    The direct transition from an insulator to a superconductor (SC) in Fermi systems is a problem of long-standing interest, which necessarily goes beyond the standard BCS paradigm of superconductivity as a Fermi surface instability. We introduce here a simple, translationally-invariant lattice fermion model that undergoes a SC-insulator transition (SIT) and elucidate its properties using analytical methods and quantum Monte Carlo simulations. We show that there is a fermionic band insulator to bosonic insulator crossover in the insulating phase and a BCS-to-BEC crossover in the SC. The SIT is always found to be from a bosonic insulator to a BEC-like SC, with an energy gap for fermions that remains finite across the SIT. The energy scales that go critical at the SIT are the gap to pair excitations in the insulator and the superfluid stiffness in the SC. In addition to giving insights into important questions about the SIT in solid state systems, our model should be experimentally realizable using ultracold fermions in optical lattices. Ref: arXiv:1507.05641 We gratefully acknowledge support from NSF DMR-1410364 (MR), DOE DE-FG02-07ER46423 (NT), and from the UC Office of the President (CC, RTS).

  6. 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.

  7. 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

  8. Superconductor-Insulator Transition and Fermi-Bose Crossovers

    NASA Astrophysics Data System (ADS)

    Loh, Yen Lee; Randeria, Mohit; Trivedi, Nandini; Chang, Chia-Chen; Scalettar, Richard

    2016-04-01

    The direct transition from an insulator to a superconductor (SC) in Fermi systems is a problem of long-standing interest, which necessarily goes beyond the standard BCS paradigm of superconductivity as a Fermi surface instability. We introduce here a simple, translationally invariant lattice fermion model that undergoes a SC-insulator transition (SIT) and elucidate its properties using analytical methods and quantum Monte Carlo simulations. We show that there is a fermionic band insulator to bosonic insulator crossover in the insulating phase and a BCS-to-BEC crossover in the SC. The SIT is always found to be from a bosonic insulator to a BEC-like SC, with an energy gap for fermions that remains finite across the SIT. The energy scales that go critical at the SIT are the gap to pair excitations in the insulator and the superfluid stiffness in the SC. In addition to giving insight into important questions about the SIT in solid-state systems, our model should be experimentally realizable using ultracold fermions in optical lattices.

  9. Bottleneck crossover between classical and quantum superfluid turbulence

    SciTech Connect

    L'vov, Victor S.; Rudenko, Oleksii; Nazarenko, Sergei V.

    2007-07-01

    We consider superfluid turbulence near absolute zero of temperature generated by classical means, e.g., towed grid or rotation but not by counterflow. We argue that such turbulence consists of a polarized tangle of mutually interacting vortex filaments with quantized vorticity. For this system, we predict and describe a bottleneck accumulation of the energy spectrum at the classical-quantum crossover scale l. Demanding the same energy flux through scales, the value of the energy at the crossover scale should exceed the Kolmogorov-41 (K41) spectrum by a large factor ln{sup 10/3}(l/a{sub 0}) (l is the mean intervortex distance and a{sub 0} is the vortex core radius) for the classical and quantum spectra to be matched in value. One of the important consequences of the bottleneck is that it causes the mean vortex line density to be considerably higher than that based on K41 alone, and this should be taken into account in (re)interpretation of new (and old) experiments as well as in further theoretical studies.

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

    PubMed Central

    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 23Na 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. PMID:26725368

  11. 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

  12. 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).

  13. 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.

  14. Modeling the covariance structure in pharmacokinetic crossover trials.

    PubMed

    Lindsey, J K; Wang, J; Byrom, W D; Jones, B

    1999-08-01

    Pharmacokinetic studies of drug and metabolite concentrations in the blood are usually conducted as crossover trials, especially in phases I and II. A longitudinal series of measurements is collected on each subject within each period. However, much of the dependence among such observations, within and between periods, is generally ignored in analyzing this type of data. Usually, only a random coefficient model is fitted for the parameters in the nonlinear mean function, along with allowing the variance to depend on the mean so that it changes over time. Here, we develop models to allow more fully for the structure of the crossover study. We introduce two levels of variance components, for the subjects and for the periods within subjects, and also an autocorrelation within periods. We also retain the time-varying variance, using a separate variance function for this, different from that for the mean. We apply this model to a phase I study of the drug flosequinan and its metabolite. This drug was developed for the treatment of heart failure. Because the metabolite also exhibits an active pharmacologic effect, study of both the parent drug and the metabolite is of interest. We find that the autocorrelation is the element in the covariance structure that most improves the fit of the model but that two levels of variance components can also be necessary. PMID:10473030

  15. Chaos based crossover and mutation for securing DICOM image.

    PubMed

    Ravichandran, Dhivya; Praveenkumar, Padmapriya; Balaguru Rayappan, John Bosco; Amirtharajan, Rengarajan

    2016-05-01

    This paper proposes a novel encryption scheme based on combining multiple chaotic maps to ensure the safe transmission of medical images. The proposed scheme uses three chaotic maps namely logistic, tent and sine maps. To achieve an efficient encryption, the proposed chao-cryptic system employs a bio-inspired crossover and mutation units to confuse and diffuse the Digital Imaging and Communications in Medicine (DICOM) image pixels. The crossover unit extensively permutes the image pixels row-wise and column-wise based on the chaotic key streams generated from the Combined Logistic-Tent (CLT) system. Prior to mutation, the pixels of the crossed over image are decomposed into two images with reduced bit depth. The decomposed images are then mutated by XOR operation with quantized chaotic sequences from Combined Logistic-Sine (CLS) system. In order to validate the sternness of the proposed algorithm, the developed chao-cryptic scheme is subjected to various security analyses such as statistical, differential, key space, key sensitivity, intentional cropping attack and chosen plaintext attack analyses. The experimental results prove the proposed DICOM cryptosystem has achieved a desirable amount of protection for real time medical image security applications. PMID:27046666

  16. 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

  17. 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

  18. A spin-crossover ionic liquid from the cationic iron(III) Schiff base complex.

    PubMed

    Okuhata, Megumi; Funasako, Yusuke; Takahashi, Kazuyuki; Mochida, Tomoyuki

    2013-09-01

    A thermochromic magnetic ionic liquid containing a cationic iron(III) Schiff-base complex has been developed, whose color and magnetic moment change with temperature because of spin crossover in the liquid state. This spin-crossover behavior closely resembles that of a solid having the same cation. PMID:23872624

  19. 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)…

  20. 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...

  1. 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...

  2. 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...

  3. 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...

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

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 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 218.107 - 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...

  6. 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...

  7. 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...

  8. 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...

  9. 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...

  10. DNA Crossover Motifs Associated with Epigenetic Modifications Delineate Open Chromatin Regions in Arabidopsis[OPEN

    PubMed Central

    Shilo, Shay; Melamed-Bessudo, Cathy; Barkai, Naama

    2015-01-01

    The rate of crossover, the reciprocal exchanges of homologous chromosomal segments, is not uniform along chromosomes differing between male and female meiocytes. To better understand the factors regulating this variable landscape, we performed a detailed genetic and epigenetic analysis of 737 crossover events in Arabidopsis thaliana. Crossovers were more frequent than expected in promoters. Three DNA motifs enriched in crossover regions and less abundant in crossover-poor pericentric regions were identified. One of these motifs, the CCN repeat, was previously unknown in plants. The A-rich motif was preferentially associated with promoters, while the CCN repeat and the CTT repeat motifs were preferentially associated with genes. Analysis of epigenetic modifications around the motifs showed, in most cases, a specific epigenetic architecture. For example, we show that there is a peak of nucleosome occupancy and of H3K4me3 around the CCN and CTT repeat motifs while nucleosome occupancy was lowest around the A-rich motif. Cytosine methylation levels showed a gradual decrease within ∼2 kb of the three motifs, being lowest at sites where crossover occurred. This landscape was conserved in the decreased DNA methylation1 mutant. In summary, the crossover motifs are associated with epigenetic landscapes corresponding to open chromatin and contributing to the nonuniformity of crossovers in Arabidopsis. PMID:26381163

  11. 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

  12. 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. PMID:20919793

  13. Synaptonemal Complex Proteins of Budding Yeast Define Reciprocal Roles in MutSγ-Mediated Crossover Formation.

    PubMed

    Voelkel-Meiman, Karen; Cheng, Shun-Yun; Morehouse, Savannah J; MacQueen, Amy J

    2016-07-01

    During meiosis, crossover recombination creates attachments between homologous chromosomes that are essential for a precise reduction in chromosome ploidy. Many of the events that ultimately process DNA repair intermediates into crossovers during meiosis occur within the context of homologous chromosomes that are tightly aligned via a conserved structure called the synaptonemal complex (SC), but the functional relationship between SC and crossover recombination remains obscure. There exists a widespread correlation across organisms between the presence of SC proteins and successful crossing over, indicating that the SC or its building block components are procrossover factors . For example, budding yeast mutants missing the SC transverse filament component, Zip1, and mutant cells missing the Zip4 protein, which is required for the elaboration of SC, fail to form MutSγ-mediated crossovers. Here we report the reciprocal phenotype-an increase in MutSγ-mediated crossovers during meiosis-in budding yeast mutants devoid of the SC central element components Ecm11 or Gmc2, and in mutants expressing a version of Zip1 missing most of its N terminus. This novel phenotypic class of SC-deficient mutants demonstrates unequivocally that the tripartite SC structure is dispensable for MutSγ-mediated crossover recombination in budding yeast. The excess crossovers observed in SC central element-deficient mutants are Msh4, Zip1, and Zip4 dependent, clearly indicating the existence of two classes of SC proteins-a class with procrossover function(s) that are also necessary for SC assembly and a class that is not required for crossover formation but essential for SC assembly. The latter class directly or indirectly limits MutSγ-mediated crossovers along meiotic chromosomes. Our findings illustrate how reciprocal roles in crossover recombination can be simultaneously linked to the SC structure. PMID:27184389

  14. 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

  15. Crossover from Quantum to Classical Creep in YBCO

    NASA Astrophysics Data System (ADS)

    Shung, E.; Beauchamp, K. M.; Rosenbaum, T. F.; Welp, U.; Crabtree, G. W.

    1996-03-01

    We use a miniature Hall probe array to measure the local magnetization relaxation S in single crystals of YBCO with columnar defects from milliKelvin to tens of Kelvin. In addition to the usual quantum signature of temperature independence of the relaxation, we probe the relationship between S and the critical current density J_c, tuned by varying columnar defect density. S can increase concurrently with Jc in the Bose glass when quantum effects dominate (K. M. Beauchamp et al., Phys. Rev. Lett. 75), 3942 (1995). Moreover, we test recent theoretical predictions of the dependence of the quantum to classical crossover temperature on critical current density (L. Radzihovsky, Phys Rev. Lett. 74), 4923 (1995).

  16. Self-adaptive genetic algorithms with simulated binary crossover.

    PubMed

    Deb, K; Beyer, H G

    2001-01-01

    Self-adaptation is an essential feature of natural evolution. However, in the context of function optimization, self-adaptation features of evolutionary search algorithms have been explored mainly with evolution strategy (ES) and evolutionary programming (EP). In this paper, we demonstrate the self-adaptive feature of real-parameter genetic algorithms (GAs) using a simulated binary crossover (SBX) operator and without any mutation operator. The connection between the working of self-adaptive ESs and real-parameter GAs with the SBX operator is also discussed. Thereafter, the self-adaptive behavior of real-parameter GAs is demonstrated on a number of test problems commonly used in the ES literature. The remarkable similarity in the working principle of real-parameter GAs and self-adaptive ESs shown in this study suggests the need for emphasizing further studies on self-adaptive GAs. PMID:11382356

  17. 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

  18. Progesterone and the premenstrual syndrome: a double blind crossover trial.

    PubMed Central

    Dennerstein, L; Spencer-Gardner, C; Gotts, G; Brown, J B; Smith, M A; Burrows, G D

    1985-01-01

    A double blind, randomised, crossover trial of oral micronised progesterone (two months) and placebo (two months) was conducted to determine whether progesterone alleviated premenstrual complaints. Twenty three women were interviewed premenstrually before treatment and in each month of treatment. They completed Moos's menstrual distress questionnaire, Beck et al's depression inventory, Spielberger et al's state anxiety inventory, the mood adjective checklist, and a daily symptom record. Analyses of data found an overall beneficial effect of being treated for all variables except restlessness, positive moods, and interest in sex. Maximum improvement occurred in the first month of treatment with progesterone. Nevertheless, an appreciably beneficial effect of progesterone over placebo for mood and some physical symptoms was identifiable after both one and two months of treatment. Further studies are needed to determine the optimum duration of treatment. PMID:3924191

  19. Berezinskii-Kosterlitz-Thouless crossover in a photonic lattice

    SciTech Connect

    Small, Eran; Pugatch, Rami; Silberberg, Yaron

    2011-01-15

    We show that a periodic two-dimensional (2D) photonic lattice with Kerr nonlinearity exhibits a Berezinskii-Kosterlitz-Thouless (BKT) crossover associated with a vortex-unbinding transition. We find that averaging over random initial conditions is equivalent to Boltzmann thermal averaging with the discrete nonlinear Schro{center_dot}{center_dot}dinger Hamiltonian. By controlling the initial randomness we can continuously vary the effective temperature. Since this Hamiltonian is in the 2D XY universality class, a BKT transition ensues. We verify this prediction using experimentally accessible observables and find good agreement between theory and simulations. This opens the possibility of experimental access to interesting phase transitions known in condensed matter using nonlinear optics.

  20. FM-AFM crossover in vanadium oxide nanomaterials

    NASA Astrophysics Data System (ADS)

    Demishev, S. V.; Chernobrovkin, A. L.; Glushkov, V. V.; Grigorieva, A. V.; Goodilin, E. A.; Sluchanko, N. E.; Samarin, N. A.; Semeno, A. V.

    2010-01-01

    The magnetic properties of nanomaterials based on vanadium oxide (multiwall nanotubes, nanorods, and nanolayers) have been investigated in the temperature range of 1.8-220 K by high-frequency (60-GHz) EPR. A transition from a ferromagnetic temperature dependence to an antiferromagnetic temperature dependence has been observed in nanorods and nanotubes with a decrease in the temperature. The FM-AFM crossover observed near T C ˜ 110 K is accompanied by a low-temperature increase in the Curie constant by a factor of 2.7-7. The comparison of the experimental data for various VO x nanoparticles indicates that the most probable cause of the change in the type of magnetic interaction is a change in the concentration of V4+ magnetic ions.

  1. Workaholism and relationship quality: a spillover-crossover perspective.

    PubMed

    Bakker, Arnold B; Demerouti, Evangelia; Burke, Ronald

    2009-01-01

    This study of 168 dual-earner couples examined the relationship between workaholism and relationship satisfaction. More specifically, on the basis of the literature, it was hypothesized that workaholism is positively related to work-family conflict. In addition, the authors predicted that workaholism is related to reduced support provided to the partner, through work-family conflict, and that individuals who receive considerable support from their partners are more satisfied with their relationship. Finally, the authors hypothesized direct crossover of relationship satisfaction between partners. The results of structural equation modeling analyses using the matched responses of both partners supported these hypotheses. Moreover, in line with predictions, the authors found that gender did not affect the strength of the relationships in the proposed model. The authors discuss workplace interventions as possible ways to help workaholics and their partners. PMID:19210044

  2. Vacuum energy density kicked by the electroweak crossover

    SciTech Connect

    Klinkhamer, F. R.; Volovik, G. E.

    2009-10-15

    Using q-theory, we show that the electroweak crossover can generate a remnant vacuum energy density {lambda}{approx}E{sub ew}{sup 8}/E{sub Planck}{sup 4}, with effective electroweak energy scale E{sub ew}{approx}10{sup 3} GeV and reduced Planck-energy scale E{sub Planck}{approx}10{sup 18} GeV. The obtained expression for the effective cosmological constant {lambda} may be a crucial input for the suggested solution by Arkani-Hamed et al. of the triple cosmic coincidence puzzle (why the orders of magnitude of the energy densities of vacuum, matter, and radiation are approximately the same in the present Universe)

  3. An inverted crossover resonance aiding laser cooling of ^171Yb

    NASA Astrophysics Data System (ADS)

    McFerran, J. J.

    2016-06-01

    We observe an inverted crossover resonance in $\\pi$-driven four-level systems, where $F'-F=0,+1$. The signal is observed through saturated absorption spectroscopy of the $(6s^{2})$ $^{1}S_{0}$ $-$ $(6s6p)$ $^{3}P_{1}$ transition in $^{171}$Yb, where the nuclear spin $I=1/2$. The enhanced absorption signal is used to generate a dispersive curve for 556 nm laser frequency stabilisation and the stabilised light cools $^{171}$Yb atoms in a two-stage magneto-optical trap, achieving temperatures of 20 $\\mu$K. The Doppler-free spectroscopy scheme is further used to measure isotopic frequency shifts and hyperfine separations for the intercombination line in ytterbium.

  4. 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

  5. Crossover from BCS to Bose superconductivity: A functional integral approach

    SciTech Connect

    Randeria, M.; Sa de Melo, C.A.R.; Engelbrecht, J.R.

    1993-04-01

    We use a functional integral formulation to study the crossover from cooperative Cooper pairing to the formation and condensation of tightly bound pairs in a 3D continuum model of fermions with attractive interactions. The inadequacy of a saddle point approximation with increasing coupling is pointed out, and the importance of temporal (quantum) fluctuations for normal state properties at intermediate and strong coupling is emphasized. In addition to recovering the Nozieres-Schmitt-Pink interpolation scheme for T{sub c}, and the Leggett variational results for T = 0, we also present results for evolution of the time-dependent Ginzburg-Landau equation and collective mode spectrum as a function of the coupling.

  6. Experimental evidence for a dynamical crossover in liquid aluminium

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    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\\cdot {{T}\\text{melting}} . 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.

  7. 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.

  8. 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.

  9. 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.

  10. Effects of capacitance at crossover wirings in power GaAs M.E.S.F.E.T.s

    NASA Astrophysics Data System (ADS)

    Aono, Y.; Higashisaka, A.; Hasegawa, F.

    1980-05-01

    Power GaAs FETs with an air-bridge crossover were compared with those of SiO2 crossover to find the effect of the capacitance at the crossover points. The capacitance of SiO2 crossover points is much smaller than that of the gate pad or the gate busbar in power GaAs FETs, and deterioration of the microwave performance due to that capacitance is negligible.

  11. 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

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

    PubMed

    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/varphi_{1}=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/varphi_{2}=0.73(4) for the DP-to-DI crossover. The inequality of varphi_{1} and varphi_{2} 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/varphi_{3}=1.23(10) , which is associated with a new independent route from the PCPD to the DP. PMID:19518439

  13. 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

  14. Reversible Photoswitching of a Spin-Crossover Molecular Complex in the Solid State at Room Temperature.

    PubMed

    Rösner, Benedikt; Milek, Magdalena; Witt, Alexander; Gobaut, Benoît; Torelli, Piero; Fink, Rainer H; Khusniyarov, Marat M

    2015-10-26

    Spin-crossover metal complexes are highly promising magnetic molecular switches for prospective molecule-based devices. The spin-crossover molecular photoswitches developed so far operate either at very low temperatures or in the liquid phase, which hinders practical applications. Herein, we present a molecular spin-crossover iron(II) complex that can be switched between paramagnetic high-spin and diamagnetic low-spin states with light at room temperature in the solid state. The reversible photoswitching is induced by alternating irradiation with ultraviolet and visible light and proceeds at the molecular level. PMID:26480333

  15. Semiflexible polymer brushes and the brush-mushroom crossover.

    PubMed

    Egorov, Sergei A; Hsu, Hsiao-Ping; Milchev, Andrey; Binder, Kurt

    2015-04-01

    Semiflexible polymers end-grafted to a repulsive planar substrate under good solvent conditions are studied by scaling arguments, computer simulations, and self-consistent field theory. Varying the chain length N, persistence length lp, and grafting density σg, the chain linear dimensions and distribution functions of all monomers and of the free chain ends are studied. Particular attention is paid to the limit of very small σg, where the grafted chains behave as "mushrooms" no longer interacting with each other. Unlike a flexible mushroom, which has a self-similar structure from the size (a) of an effective monomer up to the mushroom height (h/a ∝ N(v), ν ≈ 3/5), a semiflexible mushroom (like a free semiflexible chain) exhibits three different scaling regimes, h/a ∝ N for contour length L = Na < lp, a Gaussian regime, h/a ∝ (Llp)(1/2)/a for lp ≪ L ≪ R* ∝ (lp(2)/a), and a regime controlled by excluded volume, h/a ∝ (lp/a)(1/5)N(ν). The semiflexible brush is predicted to scale as h/a ∝ (lpaσg)(1/3)N in the excluded volume regime, and h/a ∝ (lpa(3)σ(2))(1/4)N in the Gaussian regime. Since in the volume taken by a semiflexible mushroom excluded-volume interactions are much weaker in comparison to a flexible mushroom, there occurs an additional regime where semiflexible mushrooms overlap without significant chain stretching. Moreover, since the size of a semiflexible mushroom is much larger than the size of a flexible mushroom with the same N, the crossover from mushroom to brush behavior is predicted to take place at much smaller densities than for fully flexible chains. The numerical results, however, confirm the scaling predictions only qualitatively; for chain lengths that are relevant for experiments, often intermediate effective exponents are observed due to extended crossovers. PMID:25687784

  16. 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.

  17. Coherent transport through spin-crossover magnet Fe2 complexes.

    PubMed

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

    2016-01-01

    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. PMID:26647165

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

    DOE PAGESBeta

    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

  19. 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

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    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.

  1. 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. PMID:26090609

  2. 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.

  3. 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

  4. Crossover of formic acid through Nafion ® membranes

    NASA Astrophysics Data System (ADS)

    Rhee, Young-Woo; Ha, Su Y.; Masel, Richard I.

    Formic acid has been proposed as a possible fuel for miniature fuel cells, because formic acid is expected to show low crossover and easy water management. In this paper, the permeation of formic acid through Nafion ® membranes is investigated at room temperature. It is found that the permeation of formic acid through Nafion ® 112 and 117 is much lower than that of methanol. For example, at a 1 M concentration, the steady state flux of formic acid through Nafion ® 117 is only 2.03±0.07×10 -8 mol/cm 2 s. By comparison, previous workers have observed a methanol flux of 3 to 6×10 -6 mol/cm 2 s through Nafion ® 117 under similar conditions. The flux through Nafion ® 117 increases with increasing formic acid concentration, reaching a maximum of 1.86±0.11×10 -7 mol/cm 2 s at a formic acid concentration of 10 M. The flux of formic acid is about a factor of two higher through Nafion ® 112 than through Nafion ® 117 but still low. These results show that the permeation of formic acid through Nafion ® is much slower than the permeation of methanol through the same membrane. Consequently, formic acid is an attractive alternative fuel for small polymer electrolyte membrane (PEM) fuel cells.

  5. 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

  6. Finite size induces crossover temperature in growing spin chains

    NASA Astrophysics Data System (ADS)

    Sienkiewicz, Julian; Suchecki, Krzysztof; Hołyst, Janusz A.

    2014-01-01

    We introduce a growing one-dimensional quenched spin model that bases on asymmetrical one-side Ising interactions in the presence of external field. Numerical simulations and analytical calculations based on Markov chain theory show that when the external field is smaller than the exchange coupling constant J there is a nonmonotonous dependence of the mean magnetization on the temperature in a finite system. The crossover temperature Tc corresponding to the maximal magnetization decays with system size, approximately as the inverse of the Lambert W function. The observed phenomenon can be understood as an interplay between the thermal fluctuations and the presence of the first cluster determined by initial conditions. The effect exists also when spins are not quenched but fully thermalized after the attachment to the chain. By performing tests on real data we conceive the model is in part suitable for a qualitative description of online emotional discussions arranged in a chronological order, where a spin in every node conveys emotional valence of a subsequent post.

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. 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. PMID:24201509

  12. 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.

  13. Time-dependent couplings and crossover length scales in nonequilibrium surface roughening

    NASA Astrophysics Data System (ADS)

    Pradas, Marc; López, Juan M.; Hernández-Machado, A.

    2007-07-01

    We show that time-dependent couplings may lead to nontrivial scaling properties of the surface fluctuations of the asymptotic regime in nonequilibrium kinetic roughening models. Three typical situations are studied. In the case of a crossover between two different rough regimes, the time-dependent coupling may result in anomalous scaling for scales above the crossover length. In a different setting, for a crossover from a rough to either a flat or damping regime, the time-dependent crossover length may conspire to produce a rough surface, although the most relevant term tends to flatten the surface. In addition, our analysis sheds light into an existing debate in the problem of spontaneous imbibition, where time-dependent couplings naturally arise in theoretical models and experiments.

  14. ERS-1 radial position refinement by dual crossover analysis with TOPEX/Poseidon

    NASA Astrophysics Data System (ADS)

    Carnochan, S.; Moore, P.; Ehlers, S.

    Achieving orbital accuracies in the radial direction for ERS-1 commensurate with those for TOPEX/Poseidon is of utmost importance for the integration of the two altimeter data sets. This paper outlines a procedure whereby the radial orbit error for ERS-1 is recovered as a time series expansion in the form of a finite Fourier series with additional terms for atmospheric drag, solar radiation pressure, and initial state vector mismodelling. Using a least squares collocation method with constraints derived from the JGM2 gravity field co-variance matrix, the radial error is recovered using both dual crossovers and ERS-1 single satellite crossovers. Aggregate arcs are then used to derive the ERS-1 orbit error over the repeat period of 35 days. The results are presented in the improvement of fit in the dual crossover, ERS-1 crossover and altimetry data sets as well as the recovery of an altimeter bias for the two satellites.

  15. 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...

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. 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

  1. The challenge of conducting pharmacoeconomic evaluations in oncology using crossover trials: the example of sunitinib for gastrointestinal stromal tumour.

    PubMed

    Chabot, Isabelle; LeLorier, Jacques; Blackstein, Martin E

    2008-05-01

    This paper examines the challenge of conducting economic evaluations to support patient access to cancer therapies when the cost-effectiveness estimation is hampered by crossover trial design. To demonstrate these limitations, we present the submission to the Canadian Drug Review (CDR) of a cost-effectiveness evaluation of sunitinib versus best supportive care (BSC) for the treatment of gastrointestinal stromal tumour in patients intolerant or resistant to imatinib. The economic model generated an incremental cost-effectiveness ratio for sunitinib versus BSC of dollars 79,884/quality-adjusted life-year gained. Eight months after initial submission, CDR granted a final recommendation to fund sunitinib following the manufacturer's appeal against their first recommendation. Although cost-effectiveness is an important consideration in reimbursement decisions, there is a need for improved decision-making processes for cancer drugs, as well as a better understanding of the limitations of clinical trial design. PMID:18372169

  2. Crossover versus Stabilometric Platform for the Treatment of Balance Dysfunction in Parkinson's Disease: A Randomized Study

    PubMed Central

    Frazzitta, G.; Bossio, F.; Maestri, R.; Palamara, G.; Bera, R.; Ferrazzoli, D.

    2015-01-01

    Balance dysfunctions are a major challenge in the treatment of Parkinson's disease (PD). Previous studies have shown that rehabilitation can play a role in their treatment. In this study, we have compared the efficacy of two different devices for balance training: stabilometric platform and crossover. We have enrolled 60 PD patients randomly assigned to two groups. The first one (stabilometric group) performed a 4-week cycle of balance training, using the stabilometric platform, whereas the second one (crossover group) performed a 4-week cycle of balance training, using the crossover. The outcome measures used were Unified Parkinson's Disease Rating Scale (UPDRS) part II, Berg Balance Scale (BBS), Timed Up and Go (TUG), and Six Minutes Walking Test (6MWT). Results showed that TUG, BBS, and UPDRS II improved in both groups. There was not difference in the efficacy of the two balance treatments. Patients in both groups improved also the meters walked in the 6MWT at the end of rehabilitation, but the improvement was better for patients performing crossover training. Our results show that the crossover and the stabilometric platform have the same effect on balance dysfunction of Parkinsonian patients, while crossover gets better results on the walking capacity. PMID:26583142

  3. Mitotic crossover--an evolutionary rudiment which promotes carcinogenesis of colorectal carcinoma.

    PubMed

    Rovcanin, Branislav; Ivanovski, Ivan; Djuric, Olivera; Nikolic, Dimitrije; Petrovic, Jelena; Ivanovski, Petar

    2014-09-21

    Mitotic crossover is a natural mechanism that is a main source of the genetic variability of primitive organisms. In complex organisms such as mammals, it represents an evolutionary rudiment which persisted as one of the numerous DNA repair mechanisms, and results in the production of homozygous allele combinations in all heterozygous genes located on the chromosome arm distal to the crossover. This event is familiar as loss of heterozygosity, which is one of the key mechanisms responsible for the development and progression of almost all cancers. We propose the hypothesis in which mitotic crossover is a principal source of the increased loss of heterozygosity that leads to the initiation and progression of colorectal carcinoma. The hypothesis could be tested by in vitro inhibition of Rad51 protein, orthotopic grafting of human colon cancer tissue into the gut of mice, and treatment with potential inhibitors. After these procedures, the frequency of mitotic crossover would be estimated. The development of selective inhibitors of mitotic crossover could stop further carcinogenesis of colorectal carcinoma, as well as many other neoplastic events. Loss of heterozygosity is an event responsible for carcinogenesis, its reduction by selective inhibitors of mitotic crossover could have a positive effect on cancer chemoprevention, as well as on growth reduction and a cessation in the progression of earlier developed tumors. PMID:25253953

  4. 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.

  5. Triplex-directed recognition of a DNA nanostructure assembled by crossover strand exchange.

    PubMed

    Rusling, David A; Nandhakumar, Iris S; Brown, Tom; Fox, Keith R

    2012-04-24

    DNA has been widely exploited for the self-assembly of nanosized objects and arrays that offer the potential to act as scaffolds for the spatial positioning of molecular components with nanometer precision. Methods that allow the targeting of components to specific locations within these structures are therefore highly sought after. Here we report that the triplex approach to DNA recognition, which relies on the specific binding of an oligonucleotide within the major groove of double-helical DNA, can be exploited to recognize specific loci within a DNA double-crossover tile and array, a nanostructure assembled by crossover strand exchange. The oligonucleotide can be targeted to both crossover and non-crossover strands and, surprisingly, across the region spanning the crossover junction itself. Moreover, by attaching biotin to the end of the oligonucleotide, we show that streptavidin molecules can be recruited to precise locations within a DX array, with an average spacing of 31.9 (±1.3) nm. This is a promising approach that could be exploited to introduce other components compatible with oligonucleotide synthesis into the wide variety of DNA nanostructures assembled by crossover strand exchange, such as those generated by DNA origami. PMID:22443318

  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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    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.

  8. 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

  9. 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

  10. 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

  11. 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

  12. Mrc1 and Srs2 are major actors in the regulation of spontaneous crossover

    PubMed Central

    Robert, Thomas; Dervins, Delphine; Fabre, Francis; Gangloff, Serge

    2006-01-01

    In vegetative cells, most recombination intermediates are metabolized without an association with a crossover (CO). The avoidance of COs allows for repair and prevents genomic rearrangements, potentially deleterious if the sequences involved are at ectopic locations. We have designed a system that permits to screen spontaneous intragenic recombination events in Saccharomyces cerevisiae and to investigate the CO outcome in different genetic contexts. We have analyzed the CO outcome in the absence of the Srs2 and Sgs1 helicases, DNA damage checkpoint proteins as well as in a mutant proliferating cell nuclear antigen (PCNA) and found that they all contribute to genome stability. Remarkably high effects on COs are mediated by srs2Δ, mrc1Δ and a pol30-RR mutation in PCNA. Our results support the view that Mrc1 plays a specific role in DNA replication, promoting the Srs2 recruitment to PCNA independently of checkpoint signaling. Srs2 would prevent formation of double Holliday junctions (dHJs) and thus CO formation. Sgs1 also negatively regulates CO formation but through a different process that resolves dHJs to yield non-CO products. PMID:16724109

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

    DOE PAGESBeta

    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

  14. 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. PMID:26093936

  15. COSA-1 reveals robust homeostasis and separable licensing and reinforcement steps governing meiotic crossovers.

    PubMed

    Yokoo, Rayka; Zawadzki, Karl A; Nabeshima, Kentaro; Drake, Melanie; Arur, Swathi; Villeneuve, Anne M

    2012-03-30

    Crossovers (COs) between homologous chromosomes ensure their faithful segregation during meiosis. We identify C. elegans COSA-1, a cyclin-related protein conserved in metazoa, as a key component required to convert meiotic double-strand breaks (DSBs) into COs. During late meiotic prophase, COSA-1 localizes to foci that correspond to the single CO site on each homolog pair and indicate sites of eventual concentration of other conserved CO proteins. Chromosomes gain and lose competence to load CO proteins during meiotic progression, with competence to load COSA-1 requiring prior licensing. Our data further suggest a self-reinforcing mechanism maintaining CO designation. Modeling of a nonlinear dose-response relationship between IR-induced DSBs and COSA-1 foci reveals efficient conversion of DSBs into COs when DSBs are limiting and a robust capacity to limit cytologically differentiated CO sites when DSBs are in excess. COSA-1 foci serve as a unique live cell readout for investigating CO formation and CO interference. PMID:22464324

  16. 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

  17. Cross-over study of the efficacy of four beta 2-sympathomimetic bronchodilator aerosols.

    PubMed Central

    Madsen, B W; Tandon, M K; Paterson, J W

    1979-01-01

    1 Bronchodilator efficacy of four beta 2-sympathomimetic aerosols, fenoterol, orciprenaline, salbutamol and terbutaline has been compared in nine patients with chronic stable reversible airways obstruction using a double-blind placebo controlled cross-over design. Two puffs of each agent were given on two separate occasions to each of the patients and the forced expiratory volume in one second (FEV1) and the vital capacity (VC) were measured before and 30, 90, 150 and 210 min after administration. 2 Multivariate analysis of the data at 30 min showed FEV1 and VC in these patients to be so highly correlated that they could be considered as a single variable. 3 When absolute change in VC at 30 min was used as the response criterion, efficacy of the four drugs was significantly better than placebo (P < 0.01). It was not possible to rank all four drugs in order of effectiveness; fenoterol and salbutamol were significantly better than terbutaline and orciprenaline (P < 0.01) but this was complicated by a significant interaction effect between drugs and patients (P < 0.01). 4 Similar results were obtained when absolute and relative changes in FEV1 and VC and area under the curve were used as response variables. 5 The study demonstrates that important individual differences in patient response may be concealed if only average drug effects are considered. PMID:45195

  18. 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 (ΔHelec ) 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 ΔHelec , 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. © 2015 Wiley Periodicals, Inc. PMID:26695936

  19. 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.

  20. Crossover distribution and high interference for both the X chromosome and an autosome during oogenesis and spermatogenesis in Caenorhabditis elegans.

    PubMed Central

    Meneely, Philip M; Farago, Anna F; Kauffman, Tate M

    2002-01-01

    Regulation of both the number and the location of crossovers during meiosis is important for normal chromosome segregation. We used sequence-tagged site polymorphisms to examine the distribution of all crossovers on the X chromosome during oogenesis and on one autosome during both oogenesis and spermatogenesis in Caenorhabditis elegans. The X chromosome has essentially one crossover during oogenesis, with only three possible double crossover exceptions among 220 recombinant X chromosomes. All three had one of the two crossovers in the same chromosomal interval, suggesting that crossovers in that interval do not cause interference. No other interval was associated with double crossovers. Very high interference was also found on an autosome during oogenesis, implying that each chromosome has only one crossover during oogenesis. During spermatogenesis, recombination on this autosome was reduced by approximately 30% compared to oogenesis, but the relative distribution of the residual crossovers was only slightly different. In contrast to previous results with other autosomes, no double crossover chromosomes were observed. Despite an increased frequency of nonrecombinant chromosomes, segregation of a nonrecombinant autosome during spermatogenesis appears to occur normally. This indicates that an achiasmate segregation system helps to ensure faithful disjunction of autosomes during spermatogenesis. PMID:12454064

  1. 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

  2. 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…

  3. Clarithromycin in GABA-related Hypersomnolence: A Randomized, Crossover Trial

    PubMed Central

    Trotti, Lynn Marie; Saini, Prabhjyot; Bliwise, Donald L.; Freeman, Amanda A.; Jenkins, Andrew; Rye, David B.

    2016-01-01

    Objective Some central hypersomnolence syndromes are associated with a positive allosteric modulator of GABA-A receptors in cerebrospinal fluid. Negative allosteric modulators of GABA-A receptors, including clarithromycin, have been reported to reduce sleepiness in these patients. We sought to systematically assess the effects of clarithromycin on objective vigilance and subjective sleepiness. Methods This was a five-week, randomized, placebo-controlled, double-blind, crossover trial of clarithromycin 500 mg with breakfast and lunch, in patients with hypersomnolence syndromes (excluding narcolepsy with cataplexy) and evidence for abnormal cerebrospinal fluid potentiation of GABA-A receptors. The study occurred at a university-affiliated medical center. The primary outcome measure was median reaction time on the psychomotor vigilance task (PVT) at week 2 in each condition. Secondary outcomes included the Epworth Sleepiness Scale, Stanford Sleepiness Scale, Functional Outcomes of Sleep, Pittsburgh Sleep Quality Index, the SF-36, and additional PVT measures. Results Twenty-three patients began treatment. Three patients dropped out, and final analyses were performed on twenty complete cases. Median reaction time was not significantly different between clarithromycin and placebo. Subjective measures of sleepiness were significantly improved on clarithromycin versus placebo. Altered taste perception occurred, but was the only side effect more common on clarithromycin than placebo. No serious adverse events occurred. Interpretation Subjective sleepiness, but not psychomotor vigilance, improved during a two-week course of clarithromycin. Although additional studies are needed, this suggests that clarithromycin may be a reasonable treatment option in patients with treatment-refractory hypersomnolence. This trial was registered at clinicaltrials.gov (NCT01146600) and supported by the American Sleep Medicine Foundation. PMID:26094838

  4. 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

  5. Sildenafil for Chronic Obstructive Pulmonary Disease: A Randomized Crossover Trial

    PubMed Central

    Lederer, David J.; Bartels, Matthew N.; Schluger, Neil W.; Brogan, Frances; Jellen, Patricia; Thomashow, Byron M.; Kawut, Steven M.

    2016-01-01

    Rationale Pulmonary hypertension with exercise is common in chronic obstructive pulmonary disease (COPD) and may contribute to exercise limitation in this disease. We aimed to determine the effects of treatment with sildenafil on exercise capacity in patients with COPD and emphysema. Methods We performed a randomized, double-blind, placebo-controlled 2-period crossover trial of sildenafil thrice daily in ten adults with COPD and emphysema on CT scan without pulmonary hypertension. We randomized study participants to 4 weeks of sildenafil (or placebo) followed by a 1-week washout and then 4 weeks of placebo (or sildenafil). The 2 primary outcomes were the 6-minute walk distance and oxygen consumption at peak exercise. Results Sildenafil had no effect on 6-minute walk distance (placebo-corrected difference = −7.8 m, 95% confidence interval, −23.2 to 7.5 m, p = 0.35) or oxygen consumption at peak exercise (placebo-corrected difference = −0.1 ml/kg/min, 95% confidence interval −2.1 to 1.8 ml/kg/min, p = 0.89). Sildenafil increased the alveolar-arterial oxygen gradient (p = 0.02), worsened symptoms (p = 0.04), and decreased quality-of-life (p = 0.03). Adverse events were more frequent while receiving sildenafil (p = 0.005). Conclusions Routine sildenafil administration did not have a beneficial effect on exercise capacity in patients with COPD and emphysema without pulmonary hypertension. Sildenafil significantly worsened gas exchange at rest and quality of life. (clinicaltrials.gov NCT00104637). PMID:22360383

  6. 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

  7. 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

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

    PubMed

    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

    2015-04-14

    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

  9. 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

  10. 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

  11. 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

  12. 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

  13. An innovative acupuncture treatment for primary dysmenorrhea: a randomized cross-over pilot study

    PubMed Central

    Wade, Christine M.; Abercrombie, Priscilla D.; Gomolak, Denise

    2013-01-01

    Background/Objective Dysmenorrhea is highly prevalent among adolescent women and a major cause of activity restriction. Standard pharmaceuticals used to treat dysmenorrhea are not effective for all women and have side effects that limit their use. Our study objective was to examine feasibility, acceptability, and preliminary effects of acupuncture point injection of vitamin K1 as an alternative treatment for primary dysmenorrhea among US women. Methods/Design We conducted a pilot study using a crossover trial design. Women with primary dysmenorrhea were randomized to receive vitamin K1 injection in the Spleen-6 acupuncture point at the start of menstruation followed by saline in a non-acupuncture point after two months, or the reverse order of treatments. Setting/Participants The study was conducted in the San Francisco Bay Area among women 18 and 25 years of age diagnosed with primary dysmenorrhea; fourteen women completed all study visits. Primary Outcome Measure Dysmenorrhea pain intensity was measured using a 0–10 numeric rating scale before and after injections. Results Women had an average 2.5 point decrease in pain after vitamin K1 injection in Spleen-6 (p < 0.001) compared with a 1.8 point decrease after saline (p < 0.001). Change scores of vitamin K1 compared with saline injection approached statistical significance (p < 0.10). Intensity and duration of menstrual symptoms measured by the Cox Retrospective Symptom Score also decreased following injections. After participating, 94% would still agree to go through with the injection therapy and 77% reported they would come every month were the treatment available. Conclusions Findings suggest high acceptability of acupuncture point injection of vitamin K1 as treatment for primary dysmenorrhea among young women in San Francisco. Pain decreased with both treatments, with a trend toward greater pain reduction for vitamin K1/Spleen-6 injection. This is consistent with outcomes from the Obstetrics & Gynecology

  14. Improvement of seminal parameters with Prelox: a randomized, double-blind, placebo-controlled, cross-over trial.

    PubMed

    Stanislavov, R; Nikolova, V; Rohdewald, P

    2009-03-01

    In a randomly allocated, double-blind, placebo-controlled, cross-over design, 50 infertile patients were treated for 1 month with placebo or a combination of l-arginine aspartate and Pycnogenol (Prelox). Semen samples were examined at 4 week intervals according to WHO criteria. Treatment with Prelox increased significantly the semen volume, concentration of spermatozoa, percentage of motile spermatozoa and percentage of spermatozoa with normal morphology compared with placebo. The placebo had no influence on the parameters of seminological analysis. Intake of Pycnogenol for 1 month improved the fertility index to normal values. After treatment, the fertility index decreased again to infertile status. No unwanted effects were reported. Prelox seems to be a promising alternative to treat patients with mild infertility. PMID:19142978

  15. Crossover from 3D to 2D Quantum Transport in Bi2Se3/In2Se3 Superlattices

    NASA Astrophysics Data System (ADS)

    Yanfei, Zhao; Haiwen, Liu; Xin, Guo; Ying, Jiang; Yi, Sun; Huichao, Wang; Yong, Wang; Handong, Li; Maohai, Xie; Xincheng, Xie; Jian, Wang

    2015-03-01

    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.

  16. 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. PMID:25102289

  17. Narrative, Written Sign-Outs and Interns' and Senior Medical Students' Confidence: A Randomized, Controlled Crossover Trial

    PubMed Central

    Chuang, Elizabeth; Ark, Tavinder K.; LoCurcio, Michael

    2012-01-01

    Background Failures of communication during the transfer of patient care errors. Methods We created a new format for written sign-out material, based on aviation industry practice and cognitive psychology theory, designed to improve interns' and senior medical students' communication during transfers of patient care responsibility. We carried out a randomized, blinded, crossover trial, comparing a new, narrative, written sign-out report to a usual written sign-out. Thirty-two interns and fourth-year medical students rated their confidence across various clinical tasks and answered clinical questions regarding hypothetical patients presented to them in written, new, narrative sign-out compared with the customary format. Results There was no statistical difference in confidence when interns and senior medical students received usual versus narrative sign-outs. Conclusions Although a limited measure suggested some improvement in competence, the narrative format did not improve participants' self-rated confidence during patient-care transfer. PMID:23451307

  18. The effect of music on discomfort experienced by intensive care unit patients during turning: a randomized cross-over study.

    PubMed

    Cooke, Marie; Chaboyer, Wendy; Schluter, Philip; Foster, Michelle; Harris, Denise; Teakle, Roz

    2010-04-01

    Research consistently demonstrates that intensive care unit (ICU) patients experience pain, discomfort and anxiety despite analgesic and sedative use. The most painful procedure reported by critically ill patients is being turned. Music diminishes anxiety and discomfort in some populations; however, its effect on critically ill patients remains unknown. This research aimed to identify the effect of music on discomfort experienced by ICU patients during turning using a single blind randomized cross-over design. Seventeen post-operative ICU patients were recruited and treatment order randomized. Discomfort and anxiety were measured 15 min before and immediately after two turning procedures. Findings indicated that listening to music 15 min before and during turning did not significantly reduce discomfort or anxiety. Pain management might effectively be addressing discomfort and anxiety experienced during turning. Given previous studies have identified turning as painful, current results are promising and it might be useful to determine if this is widespread. PMID:20487057

  19. 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

  20. 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.

  1. Velocity Crossover Between Hydrous and Anhydrous Forsterite at High Pressures

    SciTech Connect

    Mao, Z.; Jacobsen, S; Smyth, R; Holl, C; Frost, D; Duffy, T

    2010-01-01

    The elastic properties of hydrous forsterite, Mg{sub 2-x}SiO{sub 4}H{sub 2x}, are relevant to interpreting seismic velocity anomalies in the Earth's mantle. In this study, we used Brillouin scattering to determine the single-crystal elasticity of forsterite with 0.9(1) wt.% H{sub 2}O (x = 0.14) to 14 GPa. Aggregate bulk and shear moduli of hydrous forsterite increase with pressure at a greater rate than those of the corresponding anhydrous phase. Compared with anhydrous forsterite, we observe a 7% increase in the pressure derivative of the bulk modulus (K{prime}{sub S0} = 4.50(5)), and a 25% increase in the pressure derivative of the shear modulus (G{prime}{sub 0} = 1.75(5)) for forsterite with near maximum possible water content. Using our results, we calculated the compressional, V{sub P}, and shear, V{sub S}, velocities of forsterite as a function of pressure at 300 K. Whereas V{sub P} and V{sub S} of hydrous forsterite are 0.6% and 0.4% slower than those of anhydrous forsterite at ambient pressure, velocity crossovers at {approx} 3-4 GPa result in higher hydrous forsterite velocities at pressures corresponding to depths below {approx} 120 km. At the pressure of the 410-km discontinuity, V{sub P} and V{sub S} of hydrous forsterite exceed those of anhydrous forsterite by 1.1(1)% and 1.9(1)%, respectively. This implies that incorporation of water could decrease the magnitude of the velocity contrast at 410-km depth between forsterite and wadsleyite. Although the effects of hydration on temperature derivatives of the elastic moduli of forsterite and wadsleyite are not yet known, from the current data we estimate that the presence of {approx} 0.4 wt.% H{sub 2}O in forsterite (at 60 mol%) could lower the P and S velocity contrast at 410-km depth to 3.8(4)% and 4.8(6)%, respectively. At high pressures, hydration also decreases the V{sub P}/V{sub S} ratio of forsterite, and lowers the maximum P wave azimuthal anisotropy and S wave splitting of forsterite.

  2. 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

  3. 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. PMID:24510584

  4. 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.

  5. Separation of a molecular electronic configuration transition from the spin-crossover transition

    NASA Astrophysics Data System (ADS)

    Zhang, Xin; Mu, Sai; Chen, Jia; Chastanet, Guillaume; Nathalie, Daro; Létard, Jean-François; Palamarciuc, Tatiana; Rosa, Patrick; Liu, Jing; Arena, Dario; Sterbinsky, George; Kundys, Bohdan; Doudin, Bernard; Dowben, Peter A.

    2015-03-01

    We have investigated the unoccupied electronic structure of several molecular spin crossover systems including [Fe(H2B(pz)2)2(bipy)][Fe(H2B(pz)2)2phen],[Fe(PM-AzA)2(NCS)2]and[Fe(phen)2(NCS)2] by inverse photoemission (IPES) and X-ray absorption spectroscopy (XAS). The XAS clearly shows the change of iron L2 edge spectra, typically associated with thermal induced spin crossover, occurring at temperatures well below the temperatures of the spin crossover transition. This suggests a change in the electronic structure configuration occurring separately from the spin ordering from a low spin to high spin state. These results may be significant to understand the observations that indicate that the spin crossover transition, and certainly the unoccupied electronic structure, is influenced by electric field. In some respects, these results for the molecular spin crossover transition resemble the separation of the charge ordering transition from the ferromagnetic transition in the manganates.

  6. Ethanol crossover phenomena and its influence on the performance of DEFC

    NASA Astrophysics Data System (ADS)

    Song, S.; Zhou, W.; Tian, J.; Cai, Rui; Sun, G.; Xin, Q.; Kontou, S.; Tsiakaras, P.

    In the present work, Nafion ® membrane porosity changes were determined in aqueous ethanol solutions with different concentrations by weighing vacuum-dried and ethanol aqueous solution equilibrated membranes at room temperature. The ethanol crossover rate through Nafion ®-115 membrane at different temperatures and different concentrations had been investigated in a fuel cell test apparatus by using gas chromatography analysis. The experimental results show that the swelling degree of Nafion ® membrane gets higher as ethanol solution concentration increases. The ethanol crossover rate increases with ethanol concentration and temperature increment. The single direct ethanol fuel cell (DEFC) tests were carried out to investigate the effect of ethanol concentration on ethanol crossover and consequently, on the open circuit voltage and the cell performance of DEFC. It can be found that ethanol crossover presented a negative effect on the OCV and the cell performance of DEFC. It can also be found that an improved DEFC performance was obtained as temperature increased although the ethanol crossover rate increased with temperature increment.

  7. A light-induced spin crossover actuated single-chain magnet

    NASA Astrophysics Data System (ADS)

    Liu, Tao; Zheng, Hui; Kang, Soonchul; Shiota, Yoshihito; Hayami, Shinya; Mito, Masaki; Sato, Osamu; Yoshizawa, Kazunari; Kanegawa, Shinji; Duan, Chunying

    2013-11-01

    Both spin-crossover complexes and molecular nanomagnets display bistable magnetic states, potentially behaving as elementary binary units for information storage. It is a challenge to introduce spin-crossover units into molecular nanomagnets to switch the bistable state of the nanomagnets through external stimuli-tuned spin crossover. Here we report an iron(II) spin-crossover unit and paramagnetic iron(III) ions that are incorporated into a well-isolated double-zigzag chain. The chain exhibits thermally induced reversible spin-crossover and light-induced excited spin-state trapping at the iron(II) sites. Single-chain magnet behaviour is actuated accompanying the synergy between light-induced excited spin-state trapping at the iron(II) sites and ferromagnetic interactions between the photoinduced high-spin iron(II) and low-spin iron(III) ions in the chain. The result provides a strategy to switch the bistable state of molecular nanomagnets using external stimuli such as light and heat, with the potential to erase and write information at a molecular level.

  8. 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.

  9. The crossover between organized and disorganized states in some non-equilibrium systems

    NASA Astrophysics Data System (ADS)

    González, Diego Luis; Téllez, Gabriel

    2009-05-01

    We study numerically the crossover between organized and disorganized states of three non-equilibrium systems: the Poisson/coalesce random walk (PCRW), a one-dimensional spin system and a quasi one-dimensional lattice gas. In all cases, we describe this crossover in terms of the average spacing between particles/domain borders langS(t)rang and the spacing distribution functions p(n)(s). The nature of the crossover is not the same for all systems; however, we found that for all systems the nearest neighbor distribution p(0)(s) is well fitted by the Berry-Robnik model. The destruction of the level repulsion in the crossover between organized and disorganized states is present in all systems. Additionally, we found that the correlations between domains in the gas and spin systems are not strong and can be neglected in a first approximation, but for the PCRW the correlations between particles must be taken into account. To find p(n)(s) with n > 1, we propose two different analytical models based on the Berry-Robnik model. Our models give us a good approximation for the statistical behavior of these systems at their crossover and allow us to quantify the degree of order/disorder of the system.

  10. Popov approximation for composite bosons in the BCS-BEC crossover

    SciTech Connect

    Pieri, P.; Strinati, G.C.

    2005-03-01

    Theoretical treatments of the BCS-BEC crossover need to provide as accurate as possible descriptions of the two regimes where the diluteness condition applies, either in terms of the constituent fermions (BCS limit) or of the composite bosons which form as bound-fermion pairs (BEC limit). This has to occur via a single fermionic theory that bridges across these two limiting representations. In this paper, we set up successive improvements of the fermionic theory, that result into composite bosons described at the level of either the Bogoliubov or the Popov approximations for pointlike bosons. This work bears on the recent experimental advances on the BCS-BEC crossover with trapped Fermi atoms, which show the need for accurate theoretical descriptions of the BEC side of the crossover.

  11. 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.

  12. 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

  13. Stress- and pressure-induced iron spin-state crossover in lower mantle minerals

    NASA Astrophysics Data System (ADS)

    Glazyrin, K.; Miyajima, N.; Smith, J.; Lee, K. K.

    2013-12-01

    The spin-state crossover of ferric and ferrous iron is an important feature of major lower mantle minerals, namely magnesium silicate perovskite (Pv) and ferropericlase (Fp). This electronic transition observed in compressed Pv and Fp was initially discovered at ambient temperatures, however it is also expected for the extreme high pressure-high temperature (HP-HT) conditions endemic to planetary interiors, in particular to the Earth's lower mantle. The pressure-induced spin-state crossover of iron in Pv and Fp has been under focus of many studies, however, some aspects have not been explored in great detail. One of these aspects is the influence of non-hydrostatic macro and micro stresses on the spin-state transitions. Hydrostatic pressure is the important thermodynamic property and distinguishing effects of undesirable stresses is important from both a theoretical and experimental point of view. In this work we compress a two-phase polycrystalline mixture containing magnesium silicate Pv (Fe, Al bearing) and Fp. Using high-resolution synchrotron diffraction on laser-heated diamond-anvil cell samples, we explore characteristic signatures for non-hydrostatic stresses and their influence on the spin-state crossover of ferrous and ferric iron in Pv and Fp. We demonstrate how non-hydrostatic stresses affect the starting pressure and width of the ferrous iron spin-state crossover in Fp and compare available literature data with our results with powder and single crystal diffraction data. Finally, we use the dependence of high-spin to low-spin crossover on the ferrous iron concentration in Fp to support a recently predicted gradual decrease of ferrous iron partitioning coefficient value for Pv and Fp under compression. Our results suggest that this change occurs at HP-HT conditions even before the actual spin-state crossover of ferrous iron in Fp.

  14. 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.

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

    NASA Astrophysics Data System (ADS)

    Wu, Z.; Wentzcovitch, R. M.

    2014-12-01

    Ferropericlase (Fp) is believed to be the second most abundant phase in the lower mantle. Since the discovery of the high spin (HS) to low spin (LS) crossover in iron in Fp [1], this phenomenon has been investigated extensively experimentally and theoretically. This is a broad and smooth crossover that takes place throughout most of the lower mantle and does not produce an obvious signature in radial velocity or density profiles [2]. Therefore, the spin transition has been generally considered to be invisible to seismic waves. This study, however, shows that it can produce a peculiar effect on lateral velocity heterogeneities at certain depths[3]. 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 introduces unfamiliar effects on seismic velocities. First principles calculations indicate that anti-correlation 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 VP but not in VS. This effect is observed in tomographic 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 () heterogeneity ratio might be a useful "fingerprint" to detect the presence of Fp in the lower mantle. [1] Badro J, et al. (2003) Science 300(5620):789-791. [2] Wu Z, Justo J. F., and Wentzcovitch R. M., (2013). Phys. Rev. Lett. 110. 228501-5 [3]Wu Z., and Wentzcovitch R. M., (2014) Proc Natl Acad Sci USA. www.pnas.org/cgi/doi/10.1073/pnas.1322427111

  16. 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.

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

    PubMed

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

    2015-06-19

    A first-principles investigation into the magnetic ferroelectric PbTi(1-x)Co(x)O(3) 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 O(6) 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. PMID:26197012

  18. 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.

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

    NASA Astrophysics Data System (ADS)

    Bakalis, Evangelos; Höfinger, Siegfried; Venturini, Alessandro; Zerbetto, Francesco

    2015-06-01

    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. Spin Crossover in Ferropericlase From First-Principles Molecular Dynamics Simulations

    NASA Astrophysics Data System (ADS)

    Holmstrom, E.; Stixrude, L. P.

    2013-12-01

    Ferropericlase is believed to be the second-most abundant mineral of the lower mantle of the Earth. It is experimentally known that with increasing pressure, the iron ions in the mineral begin to collapse from a high-spin to low-spin state. This spin crossover looks certain to have geophysical effects, and hence a good theoretical understanding of the phenomenon is necessary. Using first-principles molecular dynamics simulations in conjunction with thermodynamic integration, we construct a phase diagram of the spin crossover as a function of pressure and temperature. In addition, we predict that the mineral loses its electrically insulating character within the lower mantle.

  1. 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.

  2. Spectrum and Dynamics of the BCS-BEC Crossover from a Few-Body Perspective

    SciTech Connect

    Stecher, Javier von; Greene, Chris H.

    2007-08-31

    The spectrum of two spin-up and two spin-down fermions in a trap is calculated using a correlated Gaussian basis throughout the range of the BCS-BEC crossover. These accurate calculations provide a few-body solution to the crossover problem. This solution is used to study the time evolution of the system as the scattering length is changed, mimicking experiments with Fermi gases near Fano-Feshbach resonances. The structure of avoiding crossings in the spectrum allow us to understand the dynamics of the system as a sequence of Landau-Zener transitions. Finally, we propose a ramping scheme to study atom-molecule coherence.

  3. Prolonged remission from hepatic encephalopathy with rifaximin: results of a placebo crossover analysis

    PubMed Central

    Bajaj, J S; Barrett, A C; Bortey, E; Paterson, C; Forbes, W P

    2015-01-01

    Background Rifaximin therapy reduced risk of hepatic encephalopathy (HE) recurrence and HE-related hospitalisations during a 6-month, randomised, placebo-controlled trial (RCT) and a 24-month open-label maintenance (OLM) study. However, the impact of crossover from placebo to rifaximin therapy is unclear. Aim To study the impact of crossing over from placebo to rifaximin treatment on breakthrough HE and hospitalisation rates using a within-subjects design. Methods Adults with cirrhosis and history of overt HE episodes, currently in HE remission, received placebo during the RCT and crossed over to rifaximin 550 mg twice daily during the OLM study. Rate of breakthrough overt HE episodes, hospitalisations and incidence and rate of adverse events (AEs) were analysed during RCT and first 6 months of OLM. Results Of 82 patients randomised to placebo in the RCT who crossed over to the OLM study, 39 experienced an HE episode during the RCT compared with 14 during the OLM study (P < 0.0001). Significantly lower rates of HE events were observed with rifaximin treatment compared with placebo treatment (P < 0.0001). Rates of HE-related hospitalisation were numerically lower during rifaximin treatment compared with placebo treatment, although not significant. Rates of most common AEs, serious AEs and infection-related AEs were similar between the two treatments. Conclusions This analysis confirms the repeatability of results from the RCT on safety and efficacy of rifaximin 550 mg twice daily in reducing the risk of hepatic encephalopathy recurrence, and suggests these findings are translatable outside of a rigorous, controlled trial setting. PMID:25339518

  4. 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

  5. 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.

  6. Therapeutic value of spinal cord stimulation in irritable bowel syndrome: a randomized crossover pilot study.

    PubMed

    Lind, Göran; Winter, Jaleh; Linderoth, Bengt; Hellström, Per M

    2015-05-15

    Irritable bowel syndrome (IBS) is characterized by abdominal pain and changed bowel habits. Spinal cord stimulation (SCS) has been used for treatment of chronic pain syndromes. Animal studies have shown SCS to reduce the reaction to colonic balloon distension, known to be increased in IBS patients. To elucidate the potential for SCS as treatment for IBS, a pilot study was performed. Ten IBS patients (age 26-56 yr) were recruited. A SCS system with a four-polar electrode was implanted at the T5-T8 level. After a 2-wk run-in, a randomized, crossover design SCS during 6 wk was compared with no stimulation, with an ensuing stimulation period for 12 wk; total study period 28 wk. Patients recorded pain level, pain attacks, diarrheas, and global quality of life in a diary. At end of the study patients could choose to retain their SCS system or have it removed. Nine patients completed the whole trial. During stimulation periods the median pain scores were significantly reduced from visual analogue scale (VAS) 7 (4-8) to 3 (2.5-7) and to 4 (2-6) during early and late stimulation periods, respectively (P < 0.03-0.04). Pain attacks were numerically reduced. A few patients reported reduced number of diarrheas. After study termination, six patients chose to retain their SCS system. To conclude, SCS is a minimally invasive treatment option for pain in IBS. With SCS the pain level was reduced though with merely a trend for number of attacks and diarrheas. The efficacy of SCS in IBS pain indicates a possible usefulness in other painful bowel disorders. PMID:25786486

  7. Randomised crossover trial of telemonitoring in chronic respiratory patients (TeleCRAFT trial)

    PubMed Central

    Chatwin, M; Hawkins, G; Panicchia, L; Woods, A; Hanak, A; Lucas, R; Baker, E; Ramhamdany, E; Mann, B; Riley, J; Cowie, M R; Simonds, A K

    2016-01-01

    Objective To assess the impact of home telemonitoring on health service use and quality of life in patients with severe chronic lung disease. Design Randomised crossover trial with 6 months of standard best practice clinical care (control group) and 6 months with the addition of telemonitoring. Participants 68 patients with chronic lung disease (38 with COPD; 30 with chronic respiratory failure due to other causes), who had a hospital admission for an exacerbation within 6 months of randomisation and either used long-term oxygen therapy or had an arterial oxygen saturation (SpO2) of <90% on air during the previous admission. Individuals received telemonitoring (second-generation system) via broadband link to a hospital-based care team. Outcome measures Primary outcome measure was time to first hospital admission for an acute exacerbation. Secondary outcome measures were hospital admissions, general practitioner (GP) consultations and home visits by nurses, quality of life measured by EuroQol-5D and hospital anxiety and depression (HAD) scale, and self-efficacy score (Stanford). Results Median (IQR) number of days to first admission showed no difference between the two groups—77 (114) telemonitoring, 77.5 (61) control (p=0.189). Hospital admission rate at 6 months increased (0.63 telemonitoring vs 0.32 control p=0.026). Home visits increased during telemonitoring; GP consultations were unchanged. Self-efficacy fell, while HAD depression score improved marginally during telemonitoring. Conclusions Telemonitoring added to standard care did not alter time to next acute hospital admission, increased hospital admissions and home visits overall, and did not improve quality of life in chronic respiratory patients. Trial registration number NCT02180919 (ClinicalTrials.gov). PMID:26962013

  8. Prophylactic treatment of migraine with angiotensin converting enzyme inhibitor (lisinopril): randomised, placebo controlled, crossover study

    PubMed Central

    Schrader, Harald; Stovner, Lars Jacob; Helde, Grethe; Sand, Trond; Bovim, Gunnar

    2001-01-01

    Objective To determine the efficacy of an angiotensin converting enzyme inhibitor in the prophylaxis of migraine. Design Double blind, placebo controlled, crossover study. Setting Neurological outpatient clinic. Participants Sixty patients aged 19-59 years with migraine with two to six episodes a month. Interventions Treatment period of 12 weeks with one 10 mg lisinopril tablet once daily for one week then two 10 mg lisinopril tablets once daily for 11 weeks, followed by a two week wash out period. Second treatment period of one placebo tablet once daily for one week and then two placebo tablets for 11 weeks. Thirty participants followed this schedule, and 30 received placebo followed by lisinopril. Main outcome measures Primary end points: number of hours with headache, number of days with headache, number of days with migraine. Secondary end points: headache severity index, use of drugs for symptomatic relief, quality of life and number of days taken as sick leave, acceptability of treatment. Results In the 47 participants with complete data, hours with headache, days with headache, days with migraine, and headache severity index were significantly reduced by 20% (95% confidence interval 5% to 36%), 17% (5% to 30%), 21% (9% to 34%), and 20% (3% to 37%), respectively, with lisinopril compared with placebo. Days with migraine were reduced by at least 50% in 14 participants for active treatment versus placebo and 17 patients for active treatment versus run-in period. Days with migraine were fewer by at least 50% in 14 participants for active treatment versus placebo. Intention to treat analysis of data from 55 patients supported the differences in favour of lisinopril for the primary end points. Conclusion The angiotensin converting enzyme inhibitor, lisinopril, has a clinically important prophylactic effect in migraine. PMID:11141144

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

    PubMed Central

    2012-01-01

    Background Environmental pollution is a known risk factor for multiple diseases and furthermore increases rate of hospitalisations. We investigated the correlation between emergency room admissions (ERAs) of the general population for respiratory diseases and the environmental pollutant levels in Milan, a metropolis in northern Italy. Methods We collected data from 45770 ERAs for respiratory diseases. A time-stratified case-crossover design was used to investigate the association between air pollution levels and ERAs for acute respiratory conditions. The effects of air pollutants were investigated at lag 0 to lag 5, lag 0–2 and lag 3–5 in both single and multi-pollutant models, adjusted for daily weather variables. Results An increase in ozone (O3) levels at lag 3–5 was associated with a 78% increase in the number of ERAs for asthma, especially during the warm season. Exposure to carbon monoxide (CO) proved to be a risk factor for pneumonia at lag 0–2 and in the warm season increased the risk of ERA by 66%. A significant association was found between ERAs for COPD exacerbation and levels of sulphur dioxide (SO2), CO, nitrate dioxide (NO2), and particulate matter (PM10 and PM2.5). The multipollutant model that includes all pollutants showed a significant association between CO (26%) and ERA for upper respiratory tract diseases at lag 0–2. For chronic obstructive pulmonary disease (COPD) exacerbations, only CO (OR 1.19) showed a significant association. Conclusions Exposure to environmental pollution, even at typical low levels, can increase the risk of ERA for acute respiratory diseases and exacerbation of obstructive lung diseases in the general population. PMID:23078274

  10. Airborne pollutants and lacunar stroke: a case cross-over analysis on stroke unit admissions

    PubMed Central

    Corea, Francesco; Silvestrelli, Giorgio; Baccarelli, Andrea; Giua, Alessandra; Previdi, Paolo; Siliprandi, Giorgio; Murgia, Nicola

    2012-01-01

    Particulate air pollution is known to be associated with cardiovascular disease. The relation of particulate air pollution with cerebrovascular disease (CVD) has not been extensively studied, particularly in relation to different subtypes of stroke. A time-series study was conducted to evaluate the association between daily air pollution and acute stroke unit hospitalizations in Mantua, Italy. We analyzed 781 CVD consecutive patients living in Mantua county admitted between 2006–08. Data on stroke types, demographic variables, risk factors were available from the Lombardia Stroke Registry. Daily mean value of particulate matter with a diameter <10 µm (PM10), carbon monoxide, nitric oxide, nitrogen dioxide, sulphur dioxide, benzene and ozone were used in the analysis. The association between CVD, ischemic strokes subtypes and pollutants was investigated with a case-crossover design, using conditional logistic regression analysis, adjusting for temperature, humidity, barometric pressure and holidays. Among the 781 subjects admitted 75.7% had ischemic stroke, 11.7% haemorrhagic stroke 12.6% transient ischemic attack. In men admission for stroke was associated with PM10 [odds ratio (OR) 1.01, 95%; confidence interval (CI) 1.00–1.02; P<0.05]. According to the clinical classification, lacunar anterior circulation syndrome stroke type was related to PM10 level registered on the day of admission for both genders (OR: 1.01, 95%; CI: 1.00–1.02; P<0.05) while for total anterior circulation syndrome stroke only in men (OR: 1.04, 95%; CI 1.01–1.07; P<0.05). In conclusion, our study confirms that air pollution peaks may contribute to increase the risk of hospitalization for stroke and particulate matter seems to be a significant risk factor, especially for lacunar stroke. PMID:23139849

  11. Airborne pollutants and lacunar stroke: a case cross-over analysis on stroke unit admissions.

    PubMed

    Corea, Francesco; Silvestrelli, Giorgio; Baccarelli, Andrea; Giua, Alessandra; Previdi, Paolo; Siliprandi, Giorgio; Murgia, Nicola

    2012-06-14

    Particulate air pollution is known to be associated with cardiovascular disease. The relation of particulate air pollution with cerebrovascular disease (CVD) has not been extensively studied, particularly in relation to different subtypes of stroke. A time-series study was conducted to evaluate the association between daily air pollution and acute stroke unit hospitalizations in Mantua, Italy. We analyzed 781 CVD consecutive patients living in Mantua county admitted between 2006-08. Data on stroke types, demographic variables, risk factors were available from the Lombardia Stroke Registry. Daily mean value of particulate matter with a diameter <10 µm (PM(10)), carbon monoxide, nitric oxide, nitrogen dioxide, sulphur dioxide, benzene and ozone were used in the analysis. The association between CVD, ischemic strokes subtypes and pollutants was investigated with a case-crossover design, using conditional logistic regression analysis, adjusting for temperature, humidity, barometric pressure and holidays. Among the 781 subjects admitted 75.7% had ischemic stroke, 11.7% haemorrhagic stroke 12.6% transient ischemic attack. In men admission for stroke was associated with PM(10) [odds ratio (OR) 1.01, 95%; confidence interval (CI) 1.00-1.02; P<0.05]. According to the clinical classification, lacunar anterior circulation syndrome stroke type was related to PM(10) level registered on the day of admission for both genders (OR: 1.01, 95%; CI: 1.00-1.02; P<0.05) while for total anterior circulation syndrome stroke only in men (OR: 1.04, 95%; CI 1.01-1.07; P<0.05).In conclusion, our study confirms that air pollution peaks may contribute to increase the risk of hospitalization for stroke and particulate matter seems to be a significant risk factor, especially for lacunar stroke. PMID:23139849

  12. Modafinil Improves Real Driving Performance in Patients with Hypersomnia: A Randomized Double-Blind Placebo-Controlled Crossover Clinical Trial

    PubMed Central

    Philip, Pierre; Chaufton, Cyril; Taillard, Jacques; Capelli, Aurore; Coste, Olivier; Léger, Damien; Moore, Nicholas; Sagaspe, Patricia

    2014-01-01

    Study Objective: Patients with excessive daytime sleepiness (EDS) are at high risk for driving accidents, and physicians are concerned by the effect of alerting drugs on driving skills of sleepy patients. No study has up to now investigated the effect of modafinil (a reference drug to treat EDS in patients with hypersomnia) on on-road driving performance of patients suffering from central hypersomnia. The objective is to evaluate in patients with central hypersomnia the effect of a wake-promoting drug on real driving performance and to assess the relationship between objective sleepiness and driving performance. Design and Participants: Randomized, crossover, double-blind placebo-controlled trial conducted among 13 patients with narcolepsy and 14 patients with idiopathic hypersomnia. Patients were randomly assigned to receive modafinil (400 mg) or placebo for 5 days prior to the driving test. Each condition was separated by at least 3 weeks of washout. Measurements: Mean number of Inappropriate Line Crossings, Standard Deviation of Lateral Position of the vehicle and mean sleep latency in the Maintenance of Wakefulness Test were assessed. Results: Modafinil reduced the mean number of Inappropriate Line Crossings and Standard Deviation of Lateral Position of the vehicle compared to placebo (F(1,25) = 4.88, P < 0.05 and F(1,25) = 3.87, P = 0.06 tendency). Mean sleep latency at the Maintenance of Wakefulness Test significantly correlated with the mean number of Inappropriate Line Crossings (r = -0.41, P < 0.001). Conclusions: Modafinil improves driving performance in patients with narcolepsy and idiopathic hypersomnia. The Maintenance of Wakefulness Test is a suitable clinical tool to assess fitness to drive in this population. Citation: Philip P; Chaufton C; Taillard J; Capelli A; Coste O; Léger D; Moore N; Sagaspe P. Modafinil improves real driving performance in patients with hypersomnia: a randomized double-blind placebo-controlled crossover clinical trial. SLEEP

  13. A randomized phase II crossover study of imatinib or rituximab for cutaneous sclerosis after hematopoietic cell transplantation

    PubMed Central

    Arai, Sally; Pidala, Joseph; Pusic, Iskra; Chai, Xiaoyu; Jaglowski, Samantha; Khera, Nandita; Palmer, Jeanne; Chen, George L; Jagasia, Madan H; Mayer, Sebastian A; Wood, William A; Green, Michael; Hyun, Teresa S.; Inamoto, Yoshihiro; Storer, Barry E; Miklos, David B; Shulman, Howard M.; Martin, Paul J; Sarantopoulos, Stefanie; Lee, Stephanie J; Flowers, Mary E D

    2015-01-01

    Purpose Cutaneous sclerosis (CS) occurs in 20% of patients with chronic graft-versus-host disease (GVHD) and can compromise mobility and quality of life. Experimental design We conducted a prospective, multi-center, randomized, two-arm phase II crossover trial of imatinib (200 mg daily) or rituximab (375 mg/m2 intravenously weekly × 4 doses, repeatable after 3 months) for treatment of CS diagnosed within 18 months (NCT01309997). The primary endpoint was significant clinical response (SCR) at 6 months, defined as quantitative improvement in skin sclerosis or joint range of motion. Treatment success was defined as SCR at 6 months without crossover, recurrent malignancy or death. Secondary end points included changes of B cell profiles in blood (BAFF levels and cellular subsets), patient-reported outcomes, and histopathology between responders and non-responders with each therapy. Results SCR was observed in 9 of 35 (26%, 95% CI 13-43%) participants randomized to imatinib and 10 of 37 (27%, 95% CI 14-44%) randomized to rituximab. Six (17%, 95% CI 7-34%) patients in the imatinib arm and 5 (14%, 95% CI 5-29%) in the rituximab arm had treatment success. Higher percentages of activated B cells (CD27+) were seen at enrollment in rituximab-treated patients who had treatment success (p = 0.01), but not in imatinib-treated patients. Conclusion These results support the need for more effective therapies for CS and suggest that activated B cells define a subgroup of patients with CS who are more likely to respond to rituximab. PMID:26378033

  14. 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

  15. Srs2 and Sgs1–Top3 Suppress Crossovers during Double-Strand Break Repair in Yeast

    PubMed Central

    Ira, Grzegorz; Malkova, Anna; Liberi, Giordano; Foiani, Marco; Haber, James E.

    2015-01-01

    Summary Very few gene conversions in mitotic cells are associated with crossovers, suggesting that these events are regulated. This may be important for the maintenance of genetic stability. We have analyzed the relationship between homologous recombination and crossing-over in haploid budding yeast and identified factors involved in the regulation of crossover outcomes. Gene conversions unaccompanied by a crossover appear 30 min before conversions accompanied by exchange, indicating that there are two different repair mechanisms in mitotic cells. Crossovers are rare (5%), but deleting the BLM/WRN homolog, SGS1, or the SRS2 helicase increases crossovers 2- to 3-fold. Overexpressing SRS2 nearly eliminates crossovers, whereas overexpression of RAD51 in srs2Δ cells almost completely eliminates the noncrossover recombination pathway. We suggest Sgs1 and its associated topoisomerase Top3 remove double Holliday junction intermediates from a crossover-producing repair pathway, thereby reducing crossovers. Srs2 promotes the noncrossover synthesis-dependent strand-annealing (SDSA) pathway, apparently by regulating Rad51 binding during strand exchange. PMID:14622595

  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. 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,…

  18. 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…

  19. 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

  20. 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…

  1. Improvement of the radial positioning of ERS-1 through dual crossover analysis with TOPEX/Poseidon

    NASA Astrophysics Data System (ADS)

    Carnochan, S.; Moore, P.; Ehlers, S.; Lam, C.; Woodworth, P.

    1994-01-01

    A method where both dual crossovers and single satellite crossovers are used in conjunction to determine the radial error for both Topology Ocean Experiment (TOPEX)/Poseidon and ERS-1 as a finite Fourier series, is outlined. The procedure is based on a time series expansion of the radial orbit error of ERS-1 expressed in terms of a finite Fourier series at frequencies of multiples of 1/501 cycles per revolution (for the 35 day repeat orbit), with additional terms for atmospheric drag and solar radiation pressure mismodeling as well as errors in the initial state vector. Refinement of the ERS-1 positioning is presented from solutions utilizing both the dual crossover data set by itself and in combination with ERS-1 crossover data. The zero frequency term or constant offset in the time series expansion of the ERS-1 radial orbit error is a measure of the difference between the so called altimeter biases on TOPEX/Poseidon and ERS-1. Preliminary results of this difference are presented and compared against results for both satellites from long arc orbits.

  2. 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.

  3. A method for evaluating aberration in the crossover image in mask irradiation optics of electron beam

    NASA Astrophysics Data System (ADS)

    Sohda, Yasunari; Ohta, Hiroya; Saitou, Norio

    2002-02-01

    A method for evaluating aberration in the crossover image in a cell projection lithography system has been developed. In an electron-beam lithography system of projection-type such as a cell projection lithography system, the aberration in the crossover image causes the electron beam to pass off-axis in the electron optics. Optical simulation has quantitatively shown that the aberration in the crossover image causes an electron-beam blur and a positioning error on a writing sample. The evaluating method consists of four square apertures and a mark-detection function in a cell projection system. By measuring each position of the images of the four square apertures on the writing sample at difference focuses, the aberration can be calculated. The field curvature and the astigmatism in a cell projection system were evaluated by using this method. The field curvature agrees with the simulation. In addition, the measurement of the effect of beam alignment is also demonstrated. It is thus concluded that the method can effectively evaluate the aberration in the crossover image. This method is also useful for other projection-type lithographies of charged particles—like ion and electron beams.

  4. 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

  5. 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...

  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...

  7. 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...

  8. 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...

  9. 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.

  10. 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

  11. 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...

  12. 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...

  13. 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...

  14. 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...

  15. 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...

  16. 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...

  17. 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. PMID:25333437

  18. 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…

  19. 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

  20. 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...

  1. 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…

  2. 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…

  3. 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

  4. 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).

  5. 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.

  6. 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.

  7. 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

  8. 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…

  9. Parametric Design Studies on a Direct Liquid Feed Fuel Cell

    NASA Technical Reports Server (NTRS)

    Frank, H. A.; Narayanan, S. R.; Nakamura, B.; Surampudi, S.; Halpert, G.

    1995-01-01

    Parametric design studies were carried out on a direct methanol liquid feed fuel cell employing 1 M MeOH fuel, air and oxygen as oxidant in a 2 inch x 2 inch cell employing polymeric electrolyte membranes. Measurements include voltage-current output parameters, methanol crossover rate, and impedance as a function of several design and operational variables. Design variables are described.

  10. 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.

  11. 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

  12. Inhibition of the Smc5/6 Complex during Meiosis Perturbs Joint Molecule Formation and Resolution without Significantly Changing Crossover or Non-crossover Levels

    PubMed Central

    Lilienthal, Ingrid; Kanno, Takaharu; Sjögren, Camilla

    2013-01-01

    Meiosis is a specialized cell division used by diploid organisms to form haploid gametes for sexual reproduction. Central to this reductive division is repair of endogenous DNA double-strand breaks (DSBs) induced by the meiosis-specific enzyme Spo11. These DSBs are repaired in a process called homologous recombination using the sister chromatid or the homologous chromosome as a repair template, with the homolog being the preferred substrate during meiosis. Specific products of inter-homolog recombination, called crossovers, are essential for proper homolog segregation at the first meiotic nuclear division in budding yeast and mice. This study identifies an essential role for the conserved Structural Maintenance of Chromosomes (SMC) 5/6 protein complex during meiotic recombination in budding yeast. Meiosis-specific smc5/6 mutants experience a block in DNA segregation without hindering meiotic progression. Establishment and removal of meiotic sister chromatid cohesin are independent of functional Smc6 protein. smc6 mutants also have normal levels of DSB formation and repair. Eliminating DSBs rescues the segregation block in smc5/6 mutants, suggesting that the complex has a function during meiotic recombination. Accordingly, smc6 mutants accumulate high levels of recombination intermediates in the form of joint molecules. Many of these joint molecules are formed between sister chromatids, which is not normally observed in wild-type cells. The normal formation of crossovers in smc6 mutants supports the notion that mainly inter-sister joint molecule resolution is impaired. In addition, return-to-function studies indicate that the Smc5/6 complex performs its most important functions during joint molecule resolution without influencing crossover formation. These results suggest that the Smc5/6 complex aids primarily in the resolution of joint molecules formed outside of canonical inter-homolog pathways. PMID:24244180

  13. 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

  14. The effect of crossover frequency on aided speech perception in the presence of environmental sounds

    NASA Astrophysics Data System (ADS)

    Hayes, Donald Edward, Jr.

    2002-01-01

    Since its introduction several years ago, multichannel signal processing has become a nearly ubiquitous component of programmable and digital hearing aids. Rapid development of sophisticated multichannel circuits has proceeded well ahead of sound clinical techniques to implement this new technology. Splitting the incoming acoustic signal into as few as two independent high and low frequency bandpass filters (channels) can provide significant perceptual benefits for some hearing aid wearers but no empirically derived relationship has ever been found between a given set of bandpass filter settings and improved speech perception in noise. More specifically, adjustments to the crossover frequency at which the bandpass filters intersect, has never conclusively been shown to improve speech perception in noise. This might have been because the area of crossover frequency settings in and of itself has never received a great deal of attention. The primary purpose of this study was to determine whether speech perception is significantly affected by changing the crossover frequency of a two-channel hearing aid across different sound environments. Those environmental sounds included: the steady state low frequency engine of a jet in flight, the slowly modulating wideband energy of ocean waves breaking on a beach and the high frequency transient bursts of rain hitting a tin roof. Nine participants were given the Hearing in Noise Test (HINT) and the Four Alternative Auditory Features (FAAF) test in the presence of each environmental sound. They were all tested wearing pairs of two-channel digital hearing aids with the crossover frequency set each of four ways: wideband, 800 Hz, 1600 Hz or 3200 Hz. Statistically significant group differences were found for both the 1600 Hz and 3200 Hz settings over the wideband condition on the HINT in the rain. Comparison of the HINT scores for each of the nine participants indicated that the 1600 Hz setting was superior to all others in both

  15. Development of methanol evaporation plate to reduce methanol crossover in a direct methanol fuel cell

    NASA Astrophysics Data System (ADS)

    Zhang, Ruiming

    This research focuses on methanol crossover reduction in direct methanol fuel cells (DMFC) through separating the methanol vapor from its liquid phase and feeding the vapor passively at low temperature range. Membrane electrode assemblies (MEAs) were fabricated by using commercial available membrane with different thickness at different anode catalyst loading levels, and tested under the operating conditions below 100°C in cell temperature and cathode exit open to ambient pressure. Liquid methanol transport from the anode through the membrane into cathode ("methanol crossover") is identified as one of the major efficiency losses in a DMFC. It is known that the methanol crossover rate in the vapor phase is much lower than in liquid phase. Vapor feed can be achieved by heating the liquid methanol to elevated temperatures (>100°C), but other issues limit the performance of the cell when operating above 100°C. High temperature membranes and much more active cathode catalyst structures are required, and a complex temperature control system must be employed. However, methanol vapor feed can also occur at a lower temperature range (<100°C) by separating its vapor from the liquid phase by evaporation through a porous body. The methanol crossover with this vapor feed mode is lower compared with the direct liquid methanol feed. A new method of using a methanol evaporation plate (MEP) to separate the vapor from its liquid phase to reduce the liquid methanol crossover at low temperature range is developed. A MEP plays the roles of liquid/vapor methanol phase separation and evaporation in a DMFC. The goal of this study is to develop a MEP with the proper properties to achieve high methanol phase separation efficiency and fast methanol evaporation rate over a wide range of temperature, i.e., from room temperature up to near boiling temperature (100°C). MEP materials were selected and characterized. MEPs made from three different types were tested extensively with different

  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. 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

  18. 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.

  19. Pilot crossover trial of Reiki versus rest for treating cancer-related fatigue.

    PubMed

    Tsang, Kathy L; Carlson, Linda E; Olson, Karin

    2007-03-01

    Fatigue is an extremely common side effect experienced during cancer treatment and recovery. Limited research has investigated strategies stemming from complementary and alternative medicine to reduce cancer-related fatigue. This research examined the effects of Reiki, a type of energy touch therapy, on fatigue, pain, anxiety, and overall quality of life. This study was a counterbalanced crossover trial of 2 conditions: (1) in the Reiki condition, participants received Reiki for 5 consecutive daily sessions, followed by a 1-week washout monitoring period of no treatments, then 2 additional Reiki sessions, and finally 2 weeks of no treatments, and (2) in the rest condition, participants rested for approximately 1 hour each day for 5 consecutive days, followed by a 1-week washout monitoring period of no scheduled resting and an additional week of no treatments. In both conditions, participants completed questionnaires investigating cancer-related fatigue (Functional Assessment of Cancer Therapy Fatigue subscale [FACT-F]) and overall quality of life (Functional Assessment of Cancer Therapy, General Version [FACT-G]) before and after all Reiki or resting sessions. They also completed a visual analog scale (Edmonton Symptom Assessment System [ESAS]) assessing daily tiredness, pain, and anxiety before and after each session of Reiki or rest. Sixteen patients (13 women) participated in the trial: 8 were randomized to each order of conditions (Reiki then rest; rest then Reiki). They were screened for fatigue on the ESAS tiredness item, and those scoring greater than 3 on the 0 to 10 scale were eligible for the study. They were diagnosed with a variety of cancers, most commonly colorectal (62.5%) cancer, and had a median age of 59 years. Fatigue on the FACT-F decreased within the Reiki condition (P=.05) over the course of all 7 treatments. In addition, participants in the Reiki condition experienced significant improvements in quality of life (FACT-G) compared to those in

  20. 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

  1. Motion of a Solitonic Vortex in the BEC-BCS Crossover

    NASA Astrophysics Data System (ADS)

    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 Li6 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.

  2. Dynamic structure factor of a Fermi superfluid in the BEC-BCS crossover

    NASA Astrophysics Data System (ADS)

    Ghosh, Tarun Kanti

    2007-09-01

    We consider cigar-shaped Fermi superfluid in the Bose-Einstein condensation (BEC)-BCS crossover. Using the polytropic form of equation of state, we derive low energy multibranch bosonic excitations and the corresponding density fluctuations in three different regimes along the crossover, namely weak-coupling BCS, unitarity, and molecular BEC regimes. Bragg spectroscopy can be used to probe the multibranch nature of the low-energy bosonic excitations by measuring the dynamic structure factor. Therefore we calculate the dynamic structure factor in those three different regimes. In Bragg spectroscopy, an actual observable is momentum imparted to the superfluid due to the Bragg potential. We also present results of the momentum imparted to the superfluid due to the Bragg pulses.

  3. 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.

  4. Changes in the unoccupied electronic structure of the spin crossover molecule [Co(dpzca)2

    NASA Astrophysics Data System (ADS)

    Liu, Yang; Zhang, Xin; Enders, Axel; Dowben, Peter; Luo, Jian; Zhang, Jian; N'diaye, Alpha

    We have investigated the changes in the unoccupied electronic structure of the spin crossover molecule - [Co(dpzca)2] using X-ray absorption spectroscopy (XAS) and have compared the results with magnetometry (SQUID) measurements. The studies of the variable temperature of the electronic structure of this cobalt complex with symmetric pyrazine imide ligands, -(2-pyrazylcarbonyl)-2-pyrazinecarboxamide, i.e. [Co(dpzca)2], are consistent with density functional theory (DFT). The temperature dependence of the occupancy of the high-spin state and low-spin state molecular orbital states, the unoccupied eg/t2g ratio from XAS and high spin state to low spin state ratio from molecular magnetic susceptibility χMT indicates that the low spin state is not a zero spin state, but simply a lower moment state that would occur below the spin crossover transition of [Co(dpzca)2].

  5. Anomalous compressibility of ferropericlase throughout the iron spin cross-over

    PubMed Central

    Wentzcovitch, R. M.; Justo, J. F.; Wu, Z.; da Silva, C. R. S.; Yuen, D. A.; Kohlstedt, D.

    2009-01-01

    The thermoelastic properties of ferropericlase Mg1−xFexO (x = 0.1875) throughout the iron high-to-low spin cross-over have been investigated by first principles at Earth's lower mantle conditions. This cross-over has important consequences for elasticity such as an anomalous bulk modulus (KS) reduction. At room temperature the anomaly is somewhat sharp in pressure but broadens with increasing temperature. Along a typical geotherm it occurs across most of the lower mantle with a more significant KS reduction at ≈1,400–1,600 km depth. This anomaly might also cause a reduction in the effective activation energy for diffusion creep and lead to a viscosity minimum in the mid-lower mantle, in apparent agreement with results from inversion of data related with mantle convection and postglacial rebound. PMID:19439661

  6. Mapping out the quasicondensate transition through the dimensional crossover from one to three dimensions

    SciTech Connect

    Armijo, J.; Jacqmin, T.; Bouchoule, I.; Kheruntsyan, K.

    2011-02-15

    By measuring the density fluctuations in a highly elongated weakly interacting Bose gas, we observe and quantify the transition from the ideal gas to a quasicondensate regime throughout the dimensional crossover from a purely one-dimensional (1D) to an almost three-dimensional (3D) gas. We show that that the entire transition region and the dimensional crossover are described surprisingly well by the modified Yang-Yang model. Furthermore, we find that at low temperatures the linear density at the quasicondensate transition scales according to an interaction-driven scenario of a longitudinally uniform 1D Bose gas, whereas at high temperatures it scales according to the degeneracy-driven critical scenario of transverse condensation of a 3D ideal gas.

  7. 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

  8. 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.

  9. Interaction and Disorder Effects across BCS-BEC Crossover in Two-Dimensional Fermi Gases

    NASA Astrophysics Data System (ADS)

    Tanatar, B.; Khan, A.

    2015-03-01

    We investigate the effect of static impurities in two-dimensional ultracold atomic Fermi gases. We incorporate disorder from impurities through fluctuations and study its effects on the BCS-BEC crossover. We analyze the effect of quenched disorder for various physical quantities such as chemical potential, pairing gap, density of states, spectral function, and ground-state energy. We extend our study further towards the experimentally viable quantities such as condensate fraction, sound velocity and Landau critical velocity. The results are presented as a function of binding energy and scattering length. We observe negligible effect of disorder in 2D for BCS Cooper pairs and considerable amount of depletion in the BEC regime but intriguingly the results also reveal that disorder effect is masked at the crossover region.

  10. An Angle-Based Crossover Tabu Search for Vehicle Routing Problem

    NASA Astrophysics Data System (ADS)

    Yang, Ning; Li, Ping; Li, Mingsen

    An improved tabu search - crossover tabu search (CTS) is presented which adopt the crossover operator of the genetic algorithm as the diversification strategy, and selecting elite solutions as the intensification strategies. To improve the performances, the angle-based idea of the sweep heuristic is used to confirm the neighborhood, and an object function with punishment. The angle-based CTS is applied for the vehicle routing problem. The simulating results which compared the tradition sweep heuristic and the standard tabu search shows the results got by angle-based CTS are better than those got by other two heuristics. The experiment shows the angle-based CTS has good performance on the vehicle routing problem.

  11. Topography and Gravity of 433 Eros from DSN Doppler Tracking and Altimeter Crossovers

    NASA Astrophysics Data System (ADS)

    Torrence, M.; Dunn, P.

    2004-12-01

    We have used the X-band Doppler tracking of NEAR/Shoemaker spacecraft from Earth, and NEAR Laser Rangefinder (NLR) measurements to estimate the orbital state of NEAR-Shoemaker and measurement biases, as well as spherical harmonic coefficients for the gravity field and the shape of 433 Eros. Data from the 200 km. altitude orbital stage through the high inclination 35 km orbits have been used in this analysis. Crossover measurements from NLR observations have been extended to include off-nadir observations. Meter level orbital accuracy for NEAR/Shoemaker with respect to the asteroid center of mass are attainable when the NLR observations are included in the analyses, and the orbital accuracy is improved through the use of NLR crossover information. The long wavelength gravity features have been determined to fractions of a few percent of their value. The spherical harmonic model for the shape of 433 Eros has a precision of a few meters.

  12. POLYMER DIMENSIONS IN GOOD SOLVENTS: CROSSOVER FROM SEMIDILUTE TO CONCENTRATED SOLUTIONS

    SciTech Connect

    Cheng, Gang; Melnichenko, Yuri B; Graessley, William

    2009-01-01

    Using small-angle neutron scattering, we studied the variation of the polymer radius of gyration (R{sub g}) as a function of polymer concentration ({phi}) for solutions of a flexible-chain poly(methyl methacrylate) in chloroform. We observed for the first time a distinct crossover between swollen coils in the semidilute regime, where R{sub g}{sup 2{infinity}}{phi}{sup -0.26{+-}0.03}, and unperturbed coils in the concentrated regime, where R{sub g} is independent on concentration. The crossover occurs at {phi}{double_dagger} {approx} 0.15, a value that agrees reasonably well with {phi}{double_dagger} {approx} 0.21 {+-} 0.035, estimated with a scaling relationship between {phi}{double_dagger} and the coil overlap concentration {phi}*.

  13. Crossover between strong and weak measurement in interacting many-body systems

    NASA Astrophysics Data System (ADS)

    Esin, Iliya; Romito, Alessandro; Blanter, Ya M.; Gefen, Yuval

    2016-01-01

    Measurements with variable system-detector interaction strength, ranging from weak to strong, have been recently reported in a number of electronic nanosystems. In several such instances many-body effects play a significant role. Here we consider the weak-to-strong crossover for a setup consisting of an electronic Mach-Zehnder interferometer, where a second interferometer is employed as a detector. In the context of a conditional which-path protocol, we define a generalized conditional value (GCV), and determine its full crossover between the regimes of weak and strong (projective) measurement. We find that the GCV has an oscillatory dependence on the system-detector interaction strength. These oscillations are a genuine many-body effect, and can be experimentally observed through the voltage dependence of cross current correlations.

  14. Ginzburg-Landau theory of a trapped Fermi gas with a BEC-BCS crossover

    SciTech Connect

    Huang Kun; Yu Zengqiang; Yin Lan

    2009-05-15

    The Ginzburg-Landau theory of a trapped Fermi gas with a BEC-BCS crossover is derived by the path-integral method. In addition to the standard Ginzburg-Landau equation, a second equation describing the total atom density is obtained. These two coupled equations are necessary to describe both homogeneous and inhomogeneous systems. The Ginzburg-Landau theory is valid near the transition temperature T{sub c} on both sides of the crossover. In the weakly interacting BEC region, it is also accurate at zero temperature where the Ginzburg-Landau equation can be mapped onto the Gross-Pitaevskii (GP) equation. The applicability of GP equation at finite temperature is discussed. On the BEC side, the fluctuation of the order parameter is studied and the renormalization to the molecule coupling constant is obtained.

  15. 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.

  16. Spin crossover in ferropericlase from first-principles molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Holmstrom, Eero; Stixrude, Lars

    2014-05-01

    Ferropericlase is the second-most abundant mineral of the lower mantle of the Earth. It is experimentally known that with increasing pressure, the iron ions in the mineral begin to collapse from a high-spin to low-spin state. This spin crossover alters various properties of the material, and hence a good theoretical understanding of the phenomenon is necessary. Using first-principles molecular dynamics simulations in conjunction with thermodynamic integration, we construct a phase diagram of the spin crossover as a function of pressure and temperature. In addition, we present the thermal equation of state of the mineral up to 140 GPa and 4000 K, and predict that the electrical conductivity of ferropericlase reaches semi-metallic values within the lower mantle.

  17. BCS-BEC Crossover on the Two-Dimensional Honeycomb Lattice

    SciTech Connect

    Zhao Erhai; Paramekanti, Arun

    2006-12-08

    The attractive Hubbard model on the honeycomb lattice exhibits, at half filling, a quantum critical point between a semimetal with massless Dirac fermions and an s-wave superconductor (SC). We study the BCS-BEC crossover in this model away from half filling at zero temperature and show that the appropriately defined crossover line (in the interaction-density plane) passes through the quantum critical point at half filling. For a range of densities around half filling, the 'underlying Fermi surface' of the SC, defined as the momentum space locus of minimum energy quasiparticle excitations, encloses an area which changes nonmonotonically with interaction. We also study fluctuations in the SC and the semimetal, and show the emergence of an undamped Leggett mode deep in the SC. Finally, we consider possible implications for ultracold atoms in optical lattices and the high temperature SCs.

  18. BEC-BCS crossover in a cold and magnetized two color NJL model

    NASA Astrophysics Data System (ADS)

    Duarte, Dyana C.; Allen, P. G.; Farias, R. L. S.; Manso, Pedro H. A.; Ramos, Rudnei O.; Scoccola, N. N.

    2016-01-01

    The BEC-BCS crossover for a Nambu-Jona-Lasinio (NJL) model with diquark interactions is studied in the presence of an external magnetic field. Particular attention is paid to different regularization schemes used in the literature. A thorough comparison of results is performed for the case of a cold and magnetized two-color NJL model. According to our results, the critical chemical potential for the BEC transition exhibits a clear inverse magnetic catalysis effect for magnetic fields in the range 1 ≲e B /mπ2≲20 . As for the BEC-BCS crossover, the corresponding critical chemical potential is very weakly sensitive to magnetic fields up to e B ˜9 mπ2, showing a much smaller inverse magnetic catalysis as compared to the BEC transition, and displays a strong magnetic catalysis from this point on.

  19. 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

  20. 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.

  1. 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

  2. Accuracy of the GEM-T2 geopotential from Geosat and ERS 1 crossover altimetry

    NASA Astrophysics Data System (ADS)

    Wagner, C. A.; Klokočník, J.

    1994-05-01

    Extensive analyses of altimetrically determined sea height differences at crossovers have been used to assess the accuracy of the GEM-T2 geopotential. The orbits used were determined with GEM-T2 for Geosat in its 17-day Exact Repeat Mission (ERM) in 1986-1989 and ERS 1 in both its 3-day ERM in 1991-1992 and its 35-day ERM in 1992. The data examined are completely independent of the data used in GEM-T2's development though GEM-T2 had considerable use of Doppler tracking information on Geosat. The test of the radial accuracy of the ERS 1 orbit (98.5° inclination) is especially significant because it is not ``close'' to any other orbit well represented in GEM-T2. The assessment consists of a comparison of observed mean height differences at thousands of distinct geographic locations with error projections from the GEM-T2 covariance matrix which was estimated from other data sources. This first comprehensive, independent test of the purely radial accuracy of an orbit-geopotential model clearly shows that the covariant predictions for GEM-T2 are broadly reliable for this purpose. Thus, the agreement of crossover predictions and observations suggests that the total radial errors for these ERMs, due to only to GEM-T2 (but excluding the effects of initial state error) are about 23 cm for Geosat and 115 cm (rms) for ERS 1. However, there is little detailed agreement of measurements and predictions for ERS 1 and only partial agreement in detail for Geosat. Our 30,000 mean crossover discrepancies for Geosat (derived from ERM cycles 1-44) are also shown to reduce substantially the crossover height differences in cycles 45-61, almost exactly as predicted if these are the true GEM-T2 errors for this orbit.

  3. 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

  4. 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

  5. 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.

  6. Relativistic BEC-BCS Crossover in a magnetized Nambu-Jona-Lasinio Model

    NASA Astrophysics Data System (ADS)

    Duarte, Dyana C.; Farias, R. L. S.; Manso, Pedro H. A.; Ramos, Rudnei O.

    2016-04-01

    The BEC-BCS crossover in the NJL model is studied in the presence of an external magnetic field. Particular attention is given to two different regularization schemes used in the literature and we show how they compare to each other. The comparison is made for the case of a cold and magnetized two color NJL model. We also make a brief discussion about the Nc = 3 case without magnetic fields, as an extension of this work in the future.

  7. 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.

  8. 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

  9. 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

  10. 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.

  11. 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

  12. 2D to 3D to 2D Dimensionality Crossovers in Thin BSCCO Films

    NASA Astrophysics Data System (ADS)

    Williams, Gary A.

    2003-03-01

    With increasing temperature the superfluid fraction in very thin BSCCO films undergoes a series of dimensionality crossovers. At low temperatures the strong anisotropy causes the thermal excitations to be 2D pancake-antipancake pairs in uncoupled layers. At higher temperatures where the c-axis correlation length becomes larger than a layer there is a crossover to 3D vortex loops. These are initially elliptical, but as the 3D Tc is approached they become more circular as the anisotropy scales away, as modeled by Shenoy and Chattopadhyay [1]. Close to Tc when the correlation length becomes comparable to the film thickness there is a further crossover to a 2D Kosterlitz-Thouless transition, with a drop of the superfluid fraction to zero at T_KT which can be of the order of 1 K below T_c. Good agreement with this model is found for experiments on thin BSCCO 2212 films [2]. 1. S. R. Shenoy and B. Chattopadhyay, Phys. Rev. B 51, 9129 (1995). 2. K. Osborn et al., cond-mat/0204417.

  13. Simulating dynamic crossover behavior of semiflexible linear polymers in solution and in the melt.

    PubMed

    Steinhauser, M O; Schneider, J; Blumen, A

    2009-04-28

    We present a molecular dynamics study of the dynamic scaling behavior of linear polymers in solution and in the melt when their character changes from fully flexible to semiflexible. The stiffness of the chains is determined by a bending potential. It is shown that the relaxation times tau(p) characterizing the internal dynamics of the polymer chains as well as the mean square mode amplitudes exhibit a clear crossover from Rouse to bending modes with increasing mode number p. For small mode numbers p the well-known p(-2) Rouse behavior is observed, whereas large mode numbers exhibit the p(-4) scaling, typical of the bending modes of semiflexible chains. We study the extension and the onset of the region where the crossover from p(-2) to p(-4) behavior occurs. With increasing stiffness of the chains we observe a shift of the crossover domain to smaller p-values. We also investigate the effect of chain stiffness on the monomer dynamics, based on their mean square displacements. Finally, we compare our results to previous simulations, where the scaling behavior of semiflexible chains was studied and which were restricted to a smaller range of persistence lengths l(p) and p values. PMID:19405625

  14. 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.

  15. 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

  16. 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.

  17. Quantum fluctuations in the BCS-BEC crossover of two-dimensional Fermi gases

    NASA Astrophysics Data System (ADS)

    He, Lianyi; Lü, Haifeng; Cao, Gaoqing; Hu, Hui; Liu, Xia-Ji

    2015-08-01

    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 a2 D. We find aB≃0.56 a2 D , in good agreement with the exact four-body calculation. 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.

  18. 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.

  19. 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. PMID:25873421

  20. Evolution of recombination in eutherian mammals: insights into mechanisms that affect recombination rates and crossover interference

    PubMed Central

    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

    2013-01-01

    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. PMID:24068360

  1. 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

  2. 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).

  3. 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.

  4. Calorimetric investigation of triazole-bridged Fe(II) spin-crossover one-dimensional materials: measuring the cooperativity.

    PubMed

    Roubeau, Olivier; Castro, Miguel; Burriel, Ramón; Haasnoot, Jaap G; Reedijk, Jan

    2011-03-31

    The relevance of abrupt magnetic and optical transitions exhibiting bistability in spin-crossover solids has been pointed out for their potential applications in optical or memory devices. In this respect, triazole-based one-dimensional coordination polymers are widely recognized as one of the most interesting systems. The measure of the interaction among spin-crossover centers at the origin of such cooperative behavior is of paramount importance and has so far been realized through modeling of spin-crossover curves derived mostly from magnetic measurements. Here, a new series of triazole-based one-dimensional coordination polymers of formula [Fe(Rtrz)(3)](A)(2)·xH(2)O with R = methoxyethyl and A = monovalent anion has been prepared that show complete and abrupt spin-crossover phenomenon as shown by magnetic measurements. The spin-crossover transition in these and related compounds is studied by differential scanning calorimetry, and the thermodynamic excess enthalpies and entropies associated with the phenomenon are derived systematically. Then the cooperative character of the spin-crossover in these materials is quantified by use of two widely used models, so-called Slichter and Drickamer and domain models. The same procedure is applied to spin-crossover curves of similar compounds available in the literature and for which calorimetric studies have been reported. The experimental thermodynamic figures, in particular the excess enthalpies, are shown to be clearly correlated to the output parameters of both models, thus providing a direct, experimental, quantitative measure of the cooperative character of the spin-crossover phenomenon. PMID:21381636

  5. 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

  6. 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

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

    PubMed

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

    2014-09-01

    This study evaluated whether short term exposures to NO2, O3, particulate matter <10 mm in diameter (PM10) were associated with higher risk of mortality. A total of 223,287 hypertensive patients attended public health-care services and newly prescribed at least 1 antihypertensive agent were followed-up for up to 5 years. A time-stratified, bi-directional case-crossover design was adopted. For all-cause mortality, significant positive associations were observed for NO2 and PM10 at lag 0-3 days per 10 μg/m(3) increase in concentration (excess risks 1.187%-2.501%). Significant positive associations were found for O3 at lag 1 and 2 days and the excess risks were 1.654% and 1.207%, respectively. We found similarly positive associations between these pollutants and respiratory disease mortality. These results were significant among those aged ≥65 years and in cold seasons only. Older hypertensive patients are susceptible to all-cause and respiratory disease-specific deaths from these air pollutants in cold weather. PMID:24953346

  8. 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

  9. 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

  10. Comparative palatability of two veterinary dewormers (Milpro® and Milbemax®): a blinded randomised crossover cat study

    PubMed Central

    Bernachon, N.; McGahie, D.; Corvaisier, D.; Benizeau, E.; Crastes, N.; Chaix, G.

    2014-01-01

    Background The combination of milbemycin oxime–praziquantel is widely used against the most common tapeworms and roundworms affecting cats. New veterinary presentations of this combination have recently been approved. Objective The objective of this study was to compare the palatability of two products using this combination, Milpro® and Milbemax®. Methods In all, 20 adult cats and 20 kittens were offered each product according to a randomisation table using a blinded crossover design. Prehension from the bowl, prehension from the hand and total consumption were assessed. Results Both presentations were very well tolerated in adult cats and kittens. Total prehension in adult cats and kittens was 100 and 45 per cent, respectively, for Milpro®, and 95 and 30 per cent, respectively, for Milbemax®. The percentages of adult cats and kittens which swallowed the pill after taking it into their mouth (total spontaneous consumption) were respectively 40 and 45 per cent for Milpro®, and 35 and 20 per cent for Milbemax®. Conclusion In this study, both presentations were highly attractive to cats and their respective coatings successfully covered the unpleasant odour of praziquantel, which usually repels cats. These results indicate that the palatability of Milpro® is at least as good as Milbemax® and both tablets are well accepted by adult cats and kittens. PMID:26392882

  11. 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

  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. 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

  14. Maximal fat oxidation rate and cross-over point with respect to lactate thresholds do not have good agreement.

    PubMed

    González-Haro, C

    2011-05-01

    The present cross-sectional study was designed to assess the agreement between maximal fat oxidation rate (maxFAT (OXR)) VS. Lactate Threshold (LT), and CROSS-OVER point (CO (P)) VS. Individual Anaerobic Threshold (IAT) in well-trained athletes. 2 groups of male, well-trained endurance athletes (short-distance triathletes (ST) (n=11), and road cyclists (RC) (n=11)) performed a graded cycle ergometer test to exhaustion, with 4-min stages and 30-W increments. LT, IAT, maxFAT (OXR) and CO (P) were determined for each group. FAT (OXR) and CHO (OXR) were estimated by means of indirect calorimetry and stoichiometric equations. The agreement between maxFAT (OXR) VS. LT, and CO (P) VS. IAT were determined using the Bland-Altman methodology. In spite of the low systematic error (bias) (high accuracy) for CO (P) VS. IAT, the variable error (limits of agreement) was moderate (moderate precision). For maxFAT (OXR) VS. LT the systematic error was moderate (moderate accuracy), and the variable error was moderate to high (moderate to low precision). In conclusion, the data obtained from this study shows that maxFAT (OXR) and CO (P) do not exhibit good agreement with LT and IAT, in male endurance well-trained athletes. Consequently, it is not possible to assume that maxFAT (OXR) VS. LT and CO (P) VS. IAT occurs at the same exercise intensity. PMID:21380968

  15. 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

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

    PubMed

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

    2016-01-01

    Hyper-heuristics are high-level methodologies for solving complex problems that operate on a search space of heuristics. In a selection hyper-heuristic framework, a heuristic is chosen from an existing set of low-level heuristics and applied to the current solution to produce a new solution at each point in the search. The use of crossover low-level heuristics is possible in an increasing number of general-purpose hyper-heuristic tools such as HyFlex and Hyperion. However, little work has been undertaken to assess how best to utilise it. Since a single-point search hyper-heuristic operates on a single candidate solution, and two candidate solutions are required for crossover, a mechanism is required to control the choice of the other solution. The frameworks we propose maintain a list of potential solutions for use in crossover. We investigate the use of such lists at two conceptual levels. First, crossover is controlled at the hyper-heuristic level where no problem-specific information is required. Second, it is controlled at the problem domain level where problem-specific information is used to produce good-quality solutions to use in crossover. A number of selection hyper-heuristics are compared using these frameworks over three benchmark libraries with varying properties for an NP-hard optimisation problem: the multidimensional 0-1 knapsack problem. It is shown that allowing crossover to be managed at the domain level outperforms managing crossover at the hyper-heuristic level in this problem domain. PMID:25635698

  17. 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.

  18. 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

  19. BCS-BEC crossover induced by a synthetic non-Abelian gauge field

    SciTech Connect

    Vyasanakere, Jayantha P.; Shenoy, Vijay B.; Zhang Shizhong

    2011-07-01

    We investigate the ground state of interacting spin-(1/2) fermions in three dimensions at a finite density ({rho}{approx}k{sub F}{sup 3}) in the presence of a uniform non-Abelian gauge field. The gauge-field configuration (GFC) described by a vector {lambda}{identical_to}({lambda}{sub x},{lambda}{sub y},{lambda}{sub z}), whose magnitude {lambda} 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 (k{sub F}|a{sub s}| < or approx. 1), the ground state in the absence of the gauge field ({lambda}=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 ({lambda}=0). For large gauge couplings ({lambda}/k{sub F}>>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 (a{sub s}=0{sup -}), the shape of the Fermi surface of the system undergoes a topological transition at a critical gauge coupling {lambda}{sub T}. For high-symmetry GFCs we show that the crossover from the BCS superfluid to the rashbon BEC occurs in the regime of {lambda} near {lambda}{sub T}. 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.

  20. Quantum fluctuations in the BCS-BEC crossover of two-dimensional Fermi gases

    DOE PAGESBeta

    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

  1. 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.

  2. 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

  3. 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

  4. 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

  5. Modulation of Protein Fermentation Does Not Affect Fecal Water Toxicity: A Randomized Cross-Over Study in Healthy Subjects

    PubMed Central

    Windey, Karen; De Preter, Vicky; Louat, Thierry; Schuit, Frans; Herman, Jean; Vansant, Greet; Verbeke, Kristin

    2012-01-01

    Objective Protein fermentation results in production of metabolites such as ammonia, amines and indolic, phenolic and sulfur-containing compounds. In vitro studies suggest that these metabolites might be toxic. However, human and animal studies do not consistently support these findings. We modified protein fermentation in healthy subjects to assess the effects on colonic metabolism and parameters of gut health, and to identify metabolites associated with toxicity. Design After a 2-week run-in period with normal protein intake (NP), 20 healthy subjects followed an isocaloric high protein (HP) and low protein (LP) diet for 2 weeks in a cross-over design. Protein fermentation was estimated from urinary p-cresol excretion. Fecal metabolite profiles were analyzed using GC-MS and compared using cluster analysis. DGGE was used to analyze microbiota composition. Fecal water genotoxicity and cytotoxicity were determined using the Comet assay and the WST-1-assay, respectively, and were related to the metabolite profiles. Results Dietary protein intake was significantly higher during the HP diet compared to the NP and LP diet. Urinary p-cresol excretion correlated positively with protein intake. Fecal water cytotoxicity correlated negatively with protein fermentation, while fecal water genotoxicity was not correlated with protein fermentation. Heptanal, 3-methyl-2-butanone, dimethyl disulfide and 2-propenyl ester of acetic acid are associated with genotoxicity and indole, 1-octanol, heptanal, 2,4-dithiapentane, allyl-isothiocyanate, 1-methyl-4-(1-methylethenyl)-benzene, propionic acid, octanoic acid, nonanoic acid and decanoic acid with cytotoxicity. Conclusion This study does not support a role of protein fermentation in gut toxicity. The identified metabolites can provide new insight into colonic health. Trial Registration ClinicalTrial.gov NCT01280513 PMID:23285019

  6. 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

  7. 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

  8. 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.

  9. Density Functional Plus Dynamical Mean Field Study of Spin Crossover Molecule

    NASA Astrophysics Data System (ADS)

    Chen, Jia; Millis, Andrew; Marianetti, Chris

    2015-03-01

    We report a density functional plus dynamical mean field study of spin crossover molecule Fe(phen)2(NCS)2. The temperature dependent magnetic susceptibility, Fe-d spectral and total energy were calculated and compared with experimental magnetization, metal L-edge x-ray adsorption spectroscopy. The importance of dynamic effect on energetics is demonstrated by comparison with density functional plus U method, and the role of full charge self-consistency is identified. Moreover, the local spin density plus U (LSDA+U) method with exchange interaction explicitly included is shown to dramatically overemphasize magnetic interaction.

  10. Two-channel Kondo effect and the low-temperature crossover

    NASA Astrophysics Data System (ADS)

    Keller, Andrew; Peeters, Lucas; Weymann, Ireneusz; Moca, Cătălin Paşcu; Mahalu, Diana; Umansky, Vladimir; Zaránd, Gergely; Goldhaber-Gordon, David

    2015-03-01

    The two-channel Kondo (2CK) state, where a spin-1/2 impurity is equally exchange-coupled to two independent reservoirs, is a canonical non-Fermi liquid state. Experimental observations are rare because of its sensitivity to common and hard-to-control perturbations. We implement experimentally a 2CK state in a coupled dot-grain system (Potok, et al., doi:10.1038/nature05556), and explore the physics of the low-temperature crossover: how magnetic field and gate voltage drive the system towards a Fermi liquid ground state. Our experimental findings are corroborated by detailed numerical renormalization group modeling of our device.

  11. 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

  12. Crossover between fast and slow excitation of magnetization by spin torque

    NASA Astrophysics Data System (ADS)

    Taniguchi, Tomohiro

    2016-07-01

    A crossover between two mechanisms destabilizing the magnetization in equilibrium by the spin transfer effect is found in a ferromagnetic multilayer consisting of an in-plane magnetized free layer and a perpendicularly magnetized pinned layer, where an in-plane magnetic field is applied, and electric current flows from the pinned to the free layer. A fast transition from the in-plane to the out-of-plane state occurs in the low-field region, whereas a slow transition with small-amplitude oscillation becomes dominant in the high-field region. On the other hand, only the fast transition mechanism appears for the opposite current direction.

  13. 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.

  14. Two-dimensional metal-insulator transition as a strong localization induced crossover phenomenon

    NASA Astrophysics Data System (ADS)

    Das Sarma, S.; Hwang, E. H.

    2014-06-01

    Low-disorder and high-mobility two-dimensional (2D) electron (or hole) systems confined in semiconductor heterostructures undergo an apparent metal-insulator transition (MIT) at low temperatures as the carrier density (n) is varied. In some situations, the 2D MIT can be caused at a fixed low carrier density by changing an externally applied in-plane magnetic field parallel to the 2D layer. The goal of the current work is to obtain the critical density (nc) for the 2D MIT with the system being an effective metal (Anderson insulator) for density n above (below) nc. We study the 2D MIT phenomenon theoretically as a possible strong localization induced crossover process controlled by the Ioffe-Regel criterion, kFl=1, where kF(n) is the 2D Fermi wave vector and l (n) is the disorder-limited quantum mean free path on the metallic side. Calculating the quantum mean free path in the effective metallic phase from a realistic Boltzmann transport theory including disorder scattering effects, we solve the integral equation (with l depending on n through multidimensional integrals) defined by the Ioffe-Regel criterion to obtain the nonuniversal critical density nc as a function of the applicable physical experimental parameters including disorder strength, in-plane magnetic field, spin and valley degeneracy, background dielectric constant and carrier effective mass, and temperature. The key physics underlying the nonuniversal parameter dependence of the critical density is the density dependence of the screened Coulomb disorder. Our calculated results for the crossover critical density nc appear to be in qualitative and semiquantitative agreement with the available experimental data in different 2D semiconductor systems lending credence to the possibility that the apparent 2D MIT signals the onset of the strong localization crossover in disordered 2D systems. We also compare the calculated critical density obtained from the Ioffe-Regel criterion with that obtained from a

  15. Dimensionality crossover in vortex dynamics of magnetically coupled F-S-F hybrids.

    SciTech Connect

    Karapetrov, G.; Belkin, A.; Iavarone, M.; Yefremenko, V.; Pearson, J. E.; Divan, R.; Cambel, V.; Novosad, V.; Slovak Academy of Sciences; Temple Univ.

    2011-01-19

    We report on the vortex dynamics in magnetically coupled F-S-F trilayers extracted from the analysis of the resistance-current isotherms. The superconducting thin film that is conventionally in the 2D vortex limit exhibits quite different behavior when sandwiched between ferromagnetic layers. The value of the dynamic critical exponent strongly increases in the F-S-F case due to screening of the stray vortex field by the adjacent ferromagnetic layers, leading to an effective dimensional crossover in vortex dynamics. Furthermore, the directional pinning by the magnetic stripe domains induces anisotropy in the vortex glass transition temperature and causes metastable avalanche behavior at strong driving currents.

  16. Crossover from reptation to Rouse dynamics in the extended Rubinstein-Duke model

    NASA Astrophysics Data System (ADS)

    Drzewiński, Andrzej; van Leeuwen, J. M. J.

    2008-03-01

    The competition between reptation and Rouse dynamics is incorporated in the Rubinstein-Duke model for polymer motion by extending it with sideways motions, which cross barriers and create or annihilate hernias. Using the density-matrix renormalization-group method as a solver of the master equation, the renewal time and the diffusion coefficient are calculated as functions of the length of the chain and the strength of the sideways motion. These types of moves have a strong and delicate influence on the asymptotic behavior of long polymers. The effects are analyzed as functions of the chain length in terms of effective exponents and crossover scaling functions.

  17. 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.

  18. Crossover between short- and long-time behavior of stress fluctuations and viscoelasticity of liquids.

    PubMed

    Hess, Siegfried; Kröger, Martin; Evans, Denis

    2003-04-01

    An effective viscosity coefficient is introduced based on definite time averages of equilibrium stress fluctuations rather than stress correlations. Analysis of this quantity via molecular dynamics of a simple model liquid reveals a crossover between the expected short-time elastic and the long-time viscous behavior with increasing averaging time. The procedure allows us to extract the zero-rate shear viscosity when the averaging time becomes one order of magnitude larger than the relevant relaxation time. A relationship between this effective viscosity and the dynamic viscosities is established. PMID:12786406

  19. Influence of the ligand field on slow magnetization relaxation versus spin crossover in mononuclear cobalt complexes.

    PubMed

    Habib, Fatemah; Luca, Oana R; Vieru, Veacheslav; Shiddiq, Muhandis; Korobkov, Ilia; Gorelsky, Serge I; Takase, Michael K; Chibotaru, Liviu F; Hill, Stephen; Crabtree, Robert H; Murugesu, Muralee

    2013-10-18

    The electronic and magnetic properties of the complexes [Co(terpy)Cl2 ] (1), [Co(terpy)(NCS)2 ] (2), and [Co(terpy)2 ](NCS)2 (3) were investigated. The coordination environment around Co(II) in 1 and 2 leads to a high-spin complex at low temperature and single-molecule magnet properties with multiple relaxation pathways. Changing the ligand field and geometry with an additional terpy ligand leads to spin-crossover behavior in 3 with a gradual transition from high spin to low spin. PMID:24009214

  20. Operative Management of Crossover Femoral-femoral Graft Erosion into Bladder: A Case Report.

    PubMed

    Motiani, Karan; Mahdy, Ayman

    2016-09-01

    Erosion of vascular grafts is not uncommon as seen in the recent literature. There have been many case reports documenting the work up and management of erosion of these grafts into bowel. We report a case of a crossover femoral-femoral graft that eroded into the anterior bladder wall and was incidentally found as an adherent bladder stone during cystoscopy. We demonstrate the importance of having a high level of clinical suspicion for eroding vascular grafts when preoperative imaging shows close proximity of graft to bladder. PMID:27462547

  1. 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.

  2. Comparison of different pairing fluctuation approaches to BCS-BEC crossover

    SciTech Connect

    Levin, Kathryn Chen Qijin Chien, C.-C. He Yan

    2010-02-15

    The subject of BCS-Bose-Einstein condensation (BEC) crossover is particularly exciting because of its realization in ultracold atomic Fermi gases and its possible relevance to high temperature superconductors. In this paper we review the body of theoretical work on this subject, which represents a natural extension of the seminal papers by Leggett and by Nozieres and Schmitt-Rink (NSR). The former addressed only the ground state, now known as the 'BCS-Leggett' wave-function, and the key contributions of the latter pertain to calculations of the superfluid transition temperature T{sub c}. These two papers have given rise to two main and, importantly, distinct, theoretical schools in the BCS-BEC crossover literature. The first of these extends the BCS-Leggett ground state to finite temperature and the second extends the NSR scheme away from T{sub c} both in the superfluid and normal phases. It is now rather widely accepted that these extensions of NSR produce a different ground state than that first introduced by Leggett. This observation provides a central motivation for the present paper which seeks to clarify the distinctions in the two approaches. Our analysis shows how the NSR-based approach views the bosonic contributions more completely but treats the fermions as 'quasi-free'. By contrast, the BCS-Leggett based approach treats the fermionic contributions more completely but treats the bosons as 'quasi-free'. In a related fashion, the NSR-based schemes approach the crossover between BCS and BEC by starting from the BEC limit and the BCS-Leggett based scheme approaches this crossover by starting from the BCS limit. Ultimately, one would like to combine these two schemes. There are, however, many difficult problems to surmount in any attempt to bridge the gap in the two theory classes. In this paper we review the strengths and weaknesses of both approaches. The flexibility of the BCS-Leggett based approach and its ease of handling make it widely used in T=0

  3. Anteromedial thigh perforator flap to cover the inguinal region in a crossover femorofemoral bypass

    PubMed Central

    Maldonado, Andrés A.; García-Domínguez, Jose; González-Hidalgo, Carmen; Fernández-Casado, Jose Luis; Fonseca, Raúl

    2015-01-01

    Abstract We report the case of a 48-year-old male with an exposition of a femorofemoral crossover bypass in the inguinal region and superficial femoral occlusion. This was successfully treated using an anteromedial thigh (AMT) pedicled flap based on the perforator vessel of the descending branch of the lateral circumflex femoral artery. Our report focuses on: i) considering the AMT flap as a safe and easy option to cover the inguinal region in cases of bypass exposure; ii) describing the attachment of this flap to the deep femoral artery in a patient with superficial femoral occlusion, in spite of some literature controversy. PMID:27252966

  4. 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.

  5. Dimensional-Crossover-Driven Metal-Insulator Transition in SrVO3 Ultrathin Films

    SciTech Connect

    Yoshimatsu, K; Okabe, K; Kumigashira, H; Okamoto, Satoshi; Aizaki, S; Fujimori, A; Oshima, M

    2010-01-01

    We have investigated the changes occurring in the electronic structure of digitally controlled SrVO3 ultrathin films across the dimensionality-controlled metal-insulator transition (MIT) by in situ photoemission spectroscopy. With decreasing film thickness, a pseudogap is formed at EF through spectral weight transfer from the coherent part to the incoherent part. The pseudogap finally evolves into an energy gap that is indicative of the MIT in a SrVO3 ultrathin film. The observed spectral behavior is reproduced by layer dynamical-mean-field-theory calculations, and it indicates that the observed MIT is caused by the reduction in the bandwidth due to the dimensional crossover.

  6. Two-color spectroscopy of fermions in mean-field BCS-BEC crossover theory

    SciTech Connect

    Kostrun, Marijan; Cote, Robin

    2006-04-15

    We calculate two-photon Raman spectra for fermionic atoms with interactions described by a single-mode mean-field BCS-BEC crossover theory. We compare calculated spectra of interacting and noninteracting systems and find that interactions lead to the appearance of correlated atomic pair signal due to Cooper pairs; splitting of peaks in the spectroscopic signal due to the gap in fermionic dispersion; and attenuation of signal due to the partial conversion of fermions into the corresponding single-mode dimer. By exploring the behavior of these effects, one can obtain quantitative estimates of the BCS parameters from the spectra.

  7. Long-wavelength fluctuations lead to a model of the glass crossover

    NASA Astrophysics Data System (ADS)

    Rizzo, Tommaso

    2014-06-01

    The effect of long-wavelength fluctuations on the Mode-Coupling-Theory (MCT) dynamical singularity at Tc in the β-regime is studied by means of the standard field-theoretical procedure for a genuine second-order phase transition. The resulting perturbative loop expansion can be resummed leading to an extension of the MCT equation for the critical correlator with local random fluctuations of the separation parameter. The corresponding model explains both qualitatively and quantitatively why the MCT dynamical singularity is transformed into a crossover from relaxational to activated dynamics. Dynamical Heterogeneities emerge naturally as the ergodicity-restoring mechanism instead of ad hoc hopping processes.

  8. Josephson effect in fermionic superfluids across the BEC-BCS crossover

    NASA Astrophysics Data System (ADS)

    Valtolina, Giacomo; Burchianti, Alessia; Amico, Andrea; Neri, Elettra; Xhani, Klejdja; Seman, Jorge Amin; Trombettoni, Andrea; Smerzi, Augusto; Zaccanti, Matteo; Inguscio, Massimo; Roati, Giacomo

    2015-12-01

    The Josephson effect is a macroscopic quantum phenomenon that reveals the broken symmetry associated with any superfluid state. Here we report on the observation of the Josephson effect between two fermionic superfluids coupled through a thin tunneling barrier. We show that the relative population and phase are canonically conjugate dynamical variables throughout the crossover from the molecular Bose-Einstein condensate (BEC) to the Bardeen-Cooper-Schrieffer (BCS) superfluid regime. For larger initial excitations from equilibrium, the dynamics of the superfluids become dissipative, which we ascribe to the propagation of vortices through the superfluid bulk. Our results highlight the robust nature of resonant superfluids.

  9. Josephson effect in fermionic superfluids across the BEC-BCS crossover.

    PubMed

    Valtolina, Giacomo; Burchianti, Alessia; Amico, Andrea; Neri, Elettra; Xhani, Klejdja; Seman, Jorge Amin; Trombettoni, Andrea; Smerzi, Augusto; Zaccanti, Matteo; Inguscio, Massimo; Roati, Giacomo

    2015-12-18

    The Josephson effect is a macroscopic quantum phenomenon that reveals the broken symmetry associated with any superfluid state. Here we report on the observation of the Josephson effect between two fermionic superfluids coupled through a thin tunneling barrier. We show that the relative population and phase are canonically conjugate dynamical variables throughout the crossover from the molecular Bose-Einstein condensate (BEC) to the Bardeen-Cooper-Schrieffer (BCS) superfluid regime. For larger initial excitations from equilibrium, the dynamics of the superfluids become dissipative, which we ascribe to the propagation of vortices through the superfluid bulk. Our results highlight the robust nature of resonant superfluids. PMID:26680193

  10. 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.

  11. BCS-BEC crossover and phase structure of relativistic systems: A variational approach

    SciTech Connect

    Chatterjee, Bhaswar; Mishra, Hiranmaya; Mishra, Amruta

    2009-01-01

    We investigate here the BCS-BEC crossover in relativistic systems using a variational construct for the ground state and the minimization of the thermodynamic potential. This is first studied in a four-fermion point interaction model and with a BCS type ansatz for the ground state with fermion pairs. It is shown that the antiparticle degrees of freedom play an important role in the BCS-BEC crossover physics, even when the ratio of Fermi momentum to the mass of the fermion is small. We also consider the phase structure for the case of fermion pairing with imbalanced populations. Within the ansatz, thermodynamically stable gapless modes for both fermions and antifermions are seen for strong coupling in the Bose-Einstein condensation (BEC) regime. We further investigate the effect of fluctuations of the condensate field by treating it as a dynamical field and generalize the BCS ansatz to include quanta of the condensate field also in a boson-fermion model with quartic self-interaction of the condensate field. It is seen that the critical temperature decreases with inclusion of fluctuations.

  12. Propagation of sound and supersonic bright solitons in superfluid Fermi gases in BCS-BEC crossover

    NASA Astrophysics Data System (ADS)

    Wen, Wen; Shen, Shun-Qing; Huang, Guoxiang

    2010-01-01

    We investigate the linear and nonlinear sound propagations in a cigar-shaped superfluid Fermi gas with a large particle number. We first solve analytically the eigenvalue problem of linear collective excitations and provide explicit expressions of all eigenvalues and eigenfunctions, which are valid for all superfluid regimes in the Bardeen-Cooper-Schrieffer-Bose-Einstein condensation (BCS-BEC) crossover. The linear sound speed obtained agrees well with that of a recent experimental measurement. We then consider a weak nonlinear excitation and show that the time evolution of the excitation obeys a Korteweg de Vries equation. Different from the result obtained in quasi-one-dimensional case studied previously, where subsonic dark solitons are obtained via the balance between quantum pressure and nonlinear effect, we demonstrate that bright solitons with supersonic propagating velocity can be generated in the present three-dimensional system through the balance between a waveguidelike dispersion and the interparticle interaction. The supersonic bright solitons obtained display different physical properties in different superfluid regimes and hence can be used to characterize superfluid features of the BCS-BEC crossover.

  13. Atypical BCS-BEC crossover induced by quantum-size effects

    NASA Astrophysics Data System (ADS)

    Shanenko, A. A.; Croitoru, M. D.; Vagov, A. V.; Axt, V. M.; Perali, A.; Peeters, F. M.

    2012-09-01

    Quantum-size oscillations of the basic physical characteristics of a confined fermionic condensate are a well-known phenomenon. Its conventional understanding is based on the single-particle physics, whereby the oscillations follow variations in the single-particle density of states driven by the size quantization. Here we present a study of a cigar-shaped ultracold superfluid Fermi gas, which demonstrates an important many-body aspect of the quantum-size coherent effects, overlooked previously. The many-body physics is revealed here in the atypical crossover from the Bardeen-Cooper-Schrieffer (BCS) superfluid to the Bose-Einstein condensate (BEC) induced by the size quantization of the particle motion. The single-particle energy spectrum for the transverse dimensions is tightly bound, whereas for the longitudinal direction it resembles a quasi-free dispersion. This results in the formation of a series of single-particle subbands (shells) so that the aggregate fermionic condensate becomes a coherent mixture of subband condensates. Each time when the lower edge of a subband crosses the chemical potential, the BCS-BEC crossover is approached in this subband, and the aggregate condensate contains both BCS and BEC-like components.

  14. “Slalom”: Microsurgical Cross-Over Decompression for Multilevel Degenerative Lumbar Stenosis

    PubMed Central

    2016-01-01

    Objective. Selective, bilateral multisegmental microsurgical decompression of lumbar spinal canal stenosis through separate, alternating cross-over approaches. Indications. Two-segmental and multisegmental degenerative central and lateral lumbar spinal stenosis. Contraindications. None. Surgical Technique. Minimally invasive, muscle, and facet joint-sparing bilateral decompression of the lumbar spinal canal through 2 or more alternating microsurgical cross-over approaches from one side. Results. From December 2010 until December 2015 we operated on 202 patients with 2 or multisegmental stenosis (115 f; 87 m; average age 69.3 yrs, range 51–91 yrs). All patients were suffering from symptoms typical of a degenerative lumbar spinal stenosis. All patients complained about back pain; however the leg symptoms were dominant in all cases. Per decompressed segment, the average OR time was 36 min and the blood loss 45.7 cc. Patients were mobilized 6 hrs postop and hospitalization averaged 5.9 days. A total of 116/202 patients did not need submuscular drainage. 27/202 patients suffered from a complication (13.4%). Dural tears occurred in 3.5%, an epidural hematoma in 5.5%, a deep wound infection in 1.98%, and a temporary radiculopathy postop in 1.5%. Postop follow-up ranged from 12 to 24 months. There was a significant improvement of EQ 5 D, Oswestry Disability Index (ODI), VAS for Back and Leg Pain, and preoperative standing times and walking distances. PMID:27504456

  15. Fragile-to-strong crossover coupled to the liquid-liquid transition in hydrophobic solutions.

    PubMed

    Corradini, D; Gallo, P; Buldyrev, S V; Stanley, H E

    2012-05-01

    Using discrete molecular dynamics simulations we study the relation between the thermodynamic and diffusive behaviors of a primitive model of aqueous solutions of hydrophobic solutes consisting of hard spheres in the Jagla particles solvent, close to the liquid-liquid critical point of the solvent. We find that the fragile-to-strong dynamic transition in the diffusive behavior is always coupled to the low-density-high-density liquid transition. Above the liquid-liquid critical pressure, the diffusivity crossover occurs at the Widom line, the line along which the thermodynamic response functions show maxima. Below the liquid-liquid critical pressure, the diffusivity crossover occurs when the limit of mechanical stability lines are crossed, as indicated by the hysteresis observed when going from high to low temperature and vice versa. These findings show that the strong connection between dynamics and thermodynamics found in bulk water persists in hydrophobic solutions for concentrations from low to moderate, indicating that experiments measuring the relaxation time in aqueous solutions represent a viable route for solving the open questions in the field of supercooled water. PMID:23004763

  16. Manifestation of compositional heterogeneities and ferropericlase spin crossover on mantle velocities

    NASA Astrophysics Data System (ADS)

    Wu, Z.; Wentzcovitch, R. M.

    2015-12-01

    The origin of lateral velocity heterogeneities is essential for our understanding of Earth's interior. Ferropericlase's (Fp) spin crossover (FSC) fundamentally changes the interpretation of the origin of lateral heterogeneities in the mid lower mantle. In a typical pyrolite compositional model, it induces an unusual increase in bulk sound velocity (Vϕ) with increasing temperature at mid-lower-mantle depths [1]. This reduces the sensitivity of longitudinal velocity (VP) to lateral temperature variations around 1700 km [1]. Here we show that FSC also dramatically impacts the manifestation of two important types of compositional heterogeneities, i.e., changes in iron concentration in Fp or in molar fraction of Fp. It enhances the sensitivity of Vϕ and VP to these compositional variations by several-fold at similar depths. Therefore, heterogeneities in VP tomography models are potentially good indicators of temperature versus compositional contributions to lateral velocity changes. In fact, VP heterogeneities at mid lower mantle depths common to multiple seismic models suggest that both lateral temperature and compositional variations may be significant in this region. [1] Wu, Z.Q., & Wentzcovitch, R.M. (2014). Spin crossover in ferropericlase and velocity heterogeneities in the lower mantle. Proc. Natl. Acad. Sci. U. S. A. 111: 10468-10472.

  17. The Widom line and dynamical crossover in supercritical water: Popular water models versus experiments.

    PubMed

    Corradini, D; Rovere, M; Gallo, P

    2015-09-21

    In a previous study [Gallo et al., Nat. Commun. 5, 5806 (2014)], we have shown an important connection between thermodynamic and dynamical properties of water in the supercritical region. In particular, by analyzing the experimental viscosity and the diffusion coefficient obtained in simulations performed using the TIP4P/2005 model, we have found that the line of response function maxima in the one phase region, the Widom line, is connected to a crossover from a liquid-like to a gas-like behavior of the transport coefficients. This is in agreement with recent experiments concerning the dynamics of supercritical simple fluids. We here show how different popular water models (TIP4P/2005, TIP4P, SPC/E, TIP5P, and TIP3P) perform in reproducing thermodynamic and dynamic experimental properties in the supercritical region. In particular, the comparison with experiments shows that all the analyzed models are able to qualitatively predict the dynamical crossover from a liquid-like to a gas-like behavior upon crossing the Widom line. Some of the models perform better in reproducing the pressure-temperature slope of the Widom line of supercritical water once a rigid shift of the phase diagram is applied to bring the critical points to coincide with the experimental ones. PMID:26395714

  18. Study of spin crossover nanoparticles thermal hysteresis using FORC diagrams on an Ising-like model

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    Recent developments in the synthesis and characterization of spin crossover (SCO) nanoparticles and their prospects of switching at molecular level turned these bistable compounds into possible candidates for replacing the materials used in recording media industry for development of solid state pressure and temperature sensors or for bringing contributions in engineering. Compared to bulk samples with the same chemical structure, SCO nanoparticles display different characteristics of the hysteretic and relaxation properties like the shift of the transition temperature towards lower values along with decrease of the hysteresis width with nanoparticles size. Using an Ising-like model with specific boundary conditions within a Monte Carlo procedure, we here reproduce most of the hysteretic properties of SCO nanoparticles by considering the interaction between spin crossover edge molecules and embedding surfactant molecules and we propose a complex analysis concerning the effect of the interactions and sizes during the thermal transition in systems of SCO nanoparticles by using the First Order Reversal Curves diagram method and by comparison with similar effects in mixed crystal systems.

  19. Crossover between entropic and interfacial elasticity and osmotic pressure in uniform disordered emulsions.

    PubMed

    Mason, Thomas G; Scheffold, Frank

    2014-09-28

    We develop a simple predictive model of the osmotic pressure Π and linear shear elastic modulus G of uniform disordered emulsions that includes energetic contributions from entropy and interfacial deformation. This model yields a smooth crossover between an entropically dominated G ∼ kBT/a(3) for droplet volume fractions ϕ below a jamming threshold for spheres, ϕc, and an interfacially dominated G ∼ σ/a for ϕ above ϕc, where a and σ are the undeformed radius and interfacial tension, respectively, of a droplet and T is the temperature. We show that this model reduces to the known ϕ-dependent jamming behavior G(ϕ) ∼ (σ/a)ϕ(ϕ - ϕc) as T → 0 for ϕ > ϕc of disordered uniform emulsions, and it also produces the known divergence for disordered hard spheres G(ϕ) ∼ (kBT/a(3))ϕ/(ϕc - ϕ) for ϕ < ϕc when σ → ∞. We compare predictions of this model to data for disordered uniform microscale emulsion droplets, corrected for electrostatic repulsions. The smooth crossover captures the observed trends in G and Π below ϕc better than existing analytic models of disordered emulsions, which do not make predictions below ϕc. Moreover, the model predicts that entropic contributions to the shear modulus can become more significant for nanoemulsions as compared to microscale emulsions. PMID:25111129

  20. Crossover Fields in Grain-Boundary Flux Pinning in Magnesium Diboride Films with Columnar Grains

    NASA Astrophysics Data System (ADS)

    Kim, D. H.; Hwang, T. J.; Seong, W. K.; Kang, W. N.

    We studied temperature and magnetic-field dependence of grain boundary pinning effect in MgB2 films with columnar grains by measuring the angular dependence of the resistivity and the critical current density (Jc). MgB2 films grown by using a hybrid physical chemical vapor deposition method under appropriate conditions exhibit a peculiar columnar growth with their columns oriented along the c axis. The pinning effect by grain boundaries was manifested in the comparable or even higher Jc for magnetic fields (H) parallel to the c axis (H‖c) than that for fields parallel to the ab plane (H‖ab) below certain temperature-dependent crossover fields. The crossover field, Bcr, was around 1.6 T at 5 K and decreased to around 0.9 T at 30 K depending weakly on the sample characters, and Bcr lay well below the upper critical fields in the phase diagram. Above Bcr, Jc for H‖c decreased very rapidly. The vortex spacing at Bcr was closely correlated with the temperature dependence of the penetration depth, indicating that the degree of the vortex-vortex overlap is an important parameter to determine the number of vortices allowed per unit length of grain boundaries. Thus, Bcr was thought to demarcate the accommodation capability of flux lines by the grain boundaries, and a rapid decrease of Jc above Bcr was ascribed to flux motion of the less strongly pinned vortices located away from the grain boundaries.