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Sample records for investigate intra-hospital variation

  1. Overcoming language barriers with foreign-language speaking patients: a survey to investigate intra-hospital variation in attitudes and practices

    Directory of Open Access Journals (Sweden)

    Vilpert Sarah

    2009-10-01

    Full Text Available Abstract Background Use of available interpreter services by hospital clincial staff is often suboptimal, despite evidence that trained interpreters contribute to quality of care and patient safety. Examination of intra-hospital variations in attitudes and practices regarding interpreter use can contribute to identifying factors that facilitate good practice. The purpose of this study was to describe attitudes, practices and preferences regarding communication with limited French proficiency (LFP patients, examine how these vary across professions and departments within the hospital, and identify factors associated with good practices. Methods A self-administered questionnaire was mailed to random samples of 700 doctors, 700 nurses and 93 social workers at the Geneva University Hospitals, Switzerland. Results Seventy percent of respondents encounter LFP patients at least once a month, but this varied by department. 66% of respondents said they preferred working with ad hoc interpreters (patient's family and bilingual staff, mainly because these were easier to access. During the 6 months preceding the study, ad hoc interpreters were used at least once by 71% of respondents, and professional interpreters were used at least once by 51%. Overall, only nine percent of respondents had received any training in how and why to work with a trained interpreter. Only 23.2% of respondents said the clinical service in which they currently worked encouraged them to use professional interpreters. Respondents working in services where use of professional interpreters was encouraged were more likely to be of the opinion that the hospital should systematically provide a professional interpreter to LFP patients (40.3% as compared with those working in a department that discouraged use of professional interpreters (15.5% and they used professional interpreters more often during the previous 6 months. Conclusion Attitudes and practices regarding communication with

  2. Overcoming language barriers with foreign-language speaking patients: a survey to investigate intra-hospital variation in attitudes and practices.

    Science.gov (United States)

    Hudelson, Patricia; Vilpert, Sarah

    2009-10-15

    Use of available interpreter services by hospital clinical staff is often suboptimal, despite evidence that trained interpreters contribute to quality of care and patient safety. Examination of intra-hospital variations in attitudes and practices regarding interpreter use can contribute to identifying factors that facilitate good practice. The purpose of this study was to describe attitudes, practices and preferences regarding communication with limited French proficiency (LFP) patients, examine how these vary across professions and departments within the hospital, and identify factors associated with good practices. A self-administered questionnaire was mailed to random samples of 700 doctors, 700 nurses and 93 social workers at the Geneva University Hospitals, Switzerland. Seventy percent of respondents encounter LFP patients at least once a month, but this varied by department. 66% of respondents said they preferred working with ad hoc interpreters (patient's family and bilingual staff), mainly because these were easier to access. During the 6 months preceding the study, ad hoc interpreters were used at least once by 71% of respondents, and professional interpreters were used at least once by 51%. Overall, only nine percent of respondents had received any training in how and why to work with a trained interpreter. Only 23.2% of respondents said the clinical service in which they currently worked encouraged them to use professional interpreters. Respondents working in services where use of professional interpreters was encouraged were more likely to be of the opinion that the hospital should systematically provide a professional interpreter to LFP patients (40.3%) as compared with those working in a department that discouraged use of professional interpreters (15.5%) and they used professional interpreters more often during the previous 6 months. Attitudes and practices regarding communication with LFP patients vary across professions and hospital departments. In

  3. The Relationship between Serum Hemoglobin and Creatinine Levels and Intra-Hospital Mortality and Morbidity in Acute Myocardial Infarction

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    Afsoon Fazlinezhad

    2014-09-01

    Full Text Available Background: Studies have shown that Glomerular Filtration Rate (GFR and Hemoglobin (Hb concentrations are two predictive values for ST-elevation Myocardial Infarction (MI mortality.. Objectives: This study aimed to investigate the relationship between GFR and Hb concentrations and intra-hospital mortality and electrocardiographic (ECG and echocardiographic abnormalities in ST-elevation MI patients admitted to a highly equipped hospital in Mashhad. The results will help define some factors to manage these patients more efficiently.. Patients and Methods: This descriptive study aimed to assess the relationship between Hb and GFR concentrations and mortality and morbidity among 294 randomly selected patients with ST-elevation MI. Echocardiography, ECG, and routine laboratory tests, including Hb and creatinine, were performed for all the patients. Then, the data were entered into the SPSS statistical software, version 16 and were analyzed using chi-square, t-test, and ANOVA. P < 0.05 was considered as statistically significant.. Results: Intra-hospital mortality rate was 10.5%. Besides, the results showed higher levels of serum blood sugar (P < 0.001, higher levels of creatinine (P < 0.001, lower levels of GFR (P < 0.001, lower ejection fraction (P < 0.001, higher grades of left ventricular diastolic dysfunction (P = 0.002, and lower mean Hb concentration (P = 0.022 in the dead compared to the alive cases. Besides, the patients with mechanical complications had lower Hb levels (P = 0.008. The results showed no significant relationship between creatinine level and mechanical and electrical complications (P = 0.430 and P = 0.095, respectively. However, ejection fraction was significantly associated with GFR (P = 0.016.. Conclusions: According to the results, low levels of Hb and GFR could predict mortality caused by ST-elevation MI and ECG abnormalities could notify intra-hospital death. Moreover, lower Hb levels were associated with mechanical

  4. A taxonomy and cultural analysis of intra-hospital patient transfers.

    Science.gov (United States)

    Rosenberg, Alana; Campbell Britton, Meredith; Feder, Shelli; Minges, Karl; Hodshon, Beth; Chaudhry, Sarwat I; Jenq, Grace Y; Emerson, Beth L

    2018-05-02

    Existing research on intra-hospital patient transitions focuses chiefly on handoffs, or exchanges of information, between clinicians. Less is known about patient transfers within hospitals, which include but extend beyond the exchange of information. Using participant observations and interviews at a 1,541-bed, academic, tertiary medical center, we explored the ways in which staff define and understand patient transfers between units. We conducted observations of staff (n = 16) working in four hospital departments and interviewed staff (n = 29) involved in transfers to general medicine floors from either the Emergency Department or the Medical Intensive Care Unit between February and September 2015. The collected data allowed us to understand transfers in the context of several hospital cultural microsystems. Decisions were made through the lens of the specific unit identity to which staff felt they belonged; staff actively strategized to manage workload; and empty beds were treated as a scarce commodity. Staff concepts informed the development of a taxonomy of intra-hospital transfers that includes five categories of activity: disposition, or determining the right floor and bed for the patient; notification to sending and receiving staff of patient assignment, departure and arrival; preparation to send and receive the patient; communication between sending and receiving units; and coordination to ensure that transfer components occur in a timely and seamless manner. This taxonomy widens the study of intra-hospital patient transfers from a communication activity to a complex cultural phenomenon with several categories of activity and views them as part of multidimensional hospital culture, as constructed and understood by staff. © 2018 Wiley Periodicals, Inc.

  5. Medical complications of intra-hospital patient transports: implications for architectural design and research.

    Science.gov (United States)

    Ulrich, Roger S; Zhu, Xuemei

    2007-01-01

    Literature on healthcare architecture and evidence-based design has rarely considered explicitly that patient outcomes may be worsened by intra-hospital transport (IHT), which is defined as transport of patients within the hospital. The article focuses on the effects of IHTs on patient complications and outcomes, and the implications of such impacts for designing safer, better hospitals. A review of 22 scientific studies indicates that IHTs are subject to a wide range of complications, many of which occur frequently and have distinctly detrimental effects on patient stability and outcomes. The research suggests that higher patient acuity and longer transport durations are associated with more frequent and serious IHT-related complications and outcome effects. It appears no rigorous research has compared different hospital designs and layouts with respect to having possibly differential effects on transport-related complications and worsened outcomes. Nonetheless, certain design implications can be extracted from the existing research literature, including the importance of minimizing transport delays due to restricted space and congestion, and creating layouts that shorten IHT times for high-acuity patients. Limited evidence raises the possibility that elevator-dependent vertical building layouts may increase susceptibility to transport delays that worsen complications. The strong evidence indicating that IHTs trigger complications and worsen outcomes suggests a powerful justification for adopting acuity-adaptable rooms and care models that substantially reduce transports. A program of studies is outlined to address gaps in knowledge.Key WordsPatient transports, transports within hospitals, patient safety, evidence-based design, hospital design, healthcare architecture, intra-hospital transport complications, acuity-adaptable care, elevators, outcomes.

  6. Investigating Variations in Gameplay: Cognitive Implications

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    Kamran Sedig

    2015-01-01

    Full Text Available There is increasing interest in creating computer games for learning, problem solving, and other high-level cognitive activities. When investigating whether gameplay is conducive to such activities, gameplay is often studied as a whole. As a result, cognitive implications can be linked to the game but not to its structural elements. Given that gameplay arises from interaction between the player and the game, it is the structural components of interaction that should be investigated to better understand the design of gameplay. Furthermore, minor variations in the components of interaction can have significant cognitive implications. However, such variation has not been studied yet. Thus, to gain a better understanding of how we can study the effect of interaction on the cognitive aspect of gameplay, we conducted an exploratory investigation of two computer games. These games were isomorphic at a deep level and only had one minor difference in the structure of their interaction. Volunteers played these games and discussed the cognitive processes that emerged. In one game, they primarily engaged in planning, but in the other game they primarily engaged in visualizing. This paper discusses the results of our investigation as well as its implications for the design of computer games.

  7. Multiple intra-hospital transports during relocation to a new critical care unit.

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    O'Leary, R-A; Conrick-Martin, I; O'Loughlin, C; Curran, M-R; Marsh, B

    2017-11-01

    Intra-hospital transport (IHT) of critically ill patients is associated with morbidity and mortality. Mass transfer of patients, as happens with unit relocation, is poorly described. We outline the process and adverse events associated with the relocation of a critical care unit. Extensive planning of the relocation targeted patient and equipment transfer, reduction in clinical pressure prior to the event and patient care during the relocation phase. The setting was a 30-bed, tertiary referral, combined medical and surgical critical care unit, located in a 570-bed hospital that serves as the national referral centre for cardiothoracic surgery and spinal injuries. All stakeholders relevant to the critical care unit relocation were involved, including nursing and medical staff, porters, information technology services, laboratory staff, project development managers, pharmacy staff and building contractors. Mortality at discharge from critical care unit and discharge from hospital were the main outcome measures. A wide range of adverse events were prospectively recorded, as were transfer times. Twenty-one patients underwent IHT, with a median transfer time of 10 min. Two transfers were complicated by equipment failure and three patients experienced an episode of hypotension requiring intervention. There were no cases of central venous or arterial catheter or endotracheal tube dislodgement, and hospital mortality at 30 days was 14%. Although IHT is associated with morbidity and mortality, careful logistical planning allows for efficient transfer with low complication rates.

  8. The importance of intra-hospital pharmacovigilance in the detection of medication errors

    Science.gov (United States)

    Villegas, Francisco; Figueroa-Montero, David; Barbero-Becerra, Varenka; Juárez-Hernández, Eva; Uribe, Misael; Chávez-Tapia, Norberto; González-Chon, Octavio

    2018-01-01

    Hospitalized patients are susceptible to medication errors, which represent between the fourth and the sixth cause of death. The department of intra-hospital pharmacovigilance intervenes in the entire process of medication with the purpose to prevent, repair and assess damages. To analyze medication errors reported by Mexican Fundación Clínica Médica Sur pharmacovigilance system and their impact on patients. Prospective study carried out from 2012 to 2015, where medication prescriptions given to patients were recorded. Owing to heterogeneity, data were described as absolute numbers in a logarithmic scale. 292 932 prescriptions of 56 368 patients were analyzed, and 8.9% of medication errors were identified. The treating physician was responsible of 83.32% of medication errors, residents of 6.71% and interns of 0.09%. No error caused permanent damage or death. This is the pharmacovigilance study with the largest sample size reported. Copyright: © 2018 SecretarÍa de Salud.

  9. Intra-Hospital Outcomes in ST Elevation Myocardial Infarction: Comparison of Diabetic and Non-Diabetic Patients

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    Toba Kazemi

    2015-12-01

    Full Text Available We read the interesting article entitled “the Effect of Diabetes Mellitus on Short Term Mortality and Morbidity after Isolated Coronary Artery Bypass Grafting Surgery” (1. We performed a study on intra-hospital complications in diabetic and non-diabetic patients with Acute Myocardial Infarction (AMI in Birjand, east of Iran in 2012. In our study, 479 patients with AMI (243 diabetics and 236 non-diabetics were assessed. The subjects’ mean age was 61.95 ± 13.18 years. Assessment of intra-hospital complications in the two groups revealed that recurrent angina and mortality were significantly higher in the diabetics compared to the non-diabetics (52.5% vs. 39.3%, P = 0.009; 11.2% vs. 2.6%, P = 0.012, respectively. Besides, the mean Ejection Fraction (EF was lower in the diabetics in comparison to the non-diabetics (45.26 ± 11.37% vs. 49.98 ± 10.39%, P = 0.014. Moreover, the incidence rates of intra-hospital mortality and heart failure were higher in the diabetics with AMI. This can be due to the higher prevalence of the associated risk factors, such as hypertension, dyslipidemia, and hyperglycemia, in diabetic patients and their effects on the heart. Hyperglycemia occurring after AMI is a strong and independent prognostic marker of post-MI complications. Stress, which occurs following AMI, increases insulin resistance and hyperglycemia and decreases glucose tolerance. Un-controlled diabetes in patients having AMI is accompanied by an unfavorable prognosis and may increase the risk of life-threatening complications (2. The increased risk of complications can be a possible explanation for the increase in intra-hospital mortality after AMI is diabetic patients. Various studies have indicated that initial hyperglycemia associated with failure of ST segment resolution after streptokinase infusion is followed by more extensive infarction revealed in Single-Photon Emission Computerized Tomography (SPECT, less blood flow in coronary arteries in

  10. (90377) SEDNA: INVESTIGATION OF SURFACE COMPOSITIONAL VARIATION

    International Nuclear Information System (INIS)

    Barucci, M. A.; De Bergh, C.; Merlin, F.; Morea Dalle Ore, C.; Cruikshank, D.; Alvarez-Candal, A.; Dumas, C.

    2010-01-01

    The dwarf planet (90377) Sedna is one of the most remote solar system objects accessible to investigations. To better constrain its surface composition and to investigate the possible heterogeneity of the surface of Sedna, several observations have been carried out at ESO-VLT with the powerful spectrometer SINFONI observing simultaneously the H and K bands. The analyzed spectra (obtained in 2005, 2007, and 2008) show a non-uniform spectral signature, particularly in the K band. Spectral modeling using the Shkuratov radiative transfer code for surface scattering has been performed using the various sets of data, including previous observations at visible wavelengths and photometry at 3.6 and 4.5 μm by the Spitzer Space Telescope. The visible and near-infrared spectra can be modeled with organic materials (triton and titan tholin), serpentine, and H 2 O ice in fairly significant amounts, and CH 4 , N 2 , and C 2 H 6 in varying trace amounts. One of the spectra obtained in 2005 October shows a different signature in the K band and is best modeled with CH 3 OH in place of CH 4 , with reduced amounts of serpentine and with the addition of olivine. The compositional surface heterogeneity can give input on the past history as well clues to the origin of this peculiar, distant object.

  11. Antenatal treatment with corticosteroids for preterm neonates: impact on the incidence of respiratory distress syndrome and intra-hospital mortality

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    Joice Fabíola Meneguel

    Full Text Available CONTEXT: Although the benefits of antenatal corticosteroids have been widely demonstrated in other countries, there are few studies among Brazilian newborn infants. OBJECTIVE: To evaluate the effectiveness of antenatal corticosteroids on the incidence of respiratory distress syndrome and intra-hospital mortality among neonates with a gestational age of less than 34 weeks. TYPE OF STUDY: Cross-sectional. SETTING: A tertiary-care hospital. PARTICIPANTS: Neonates exposed to any dose of antenatal corticosteroids for fetal maturation up to 7 days before delivery, and newborns paired by sex, birth weight, gestational age and time of birth that were not exposed to antenatal corticosteroids. The sample obtained consisted of 205 exposed newborns, 205 non-exposed and 39 newborns exposed to antenatal corticosteroids for whom it was not possible to find an unexposed pair. PROCEDURES: Analysis of maternal and newborn records. MAIN MEASUREMENTS: The primary clinical outcomes for the two groups were compared: the incidence of respiratory distress syndrome and intra-hospital mortality; as well as secondary outcomes related to neonatal morbidity. RESULTS: Antenatal corticosteroids reduced the occurrence of respiratory distress syndrome (OR: 0.33; 95% CI: 0.21-0.51 and the protective effect persisted when adjusted for weight, gestational age and the presence of asphyxia (adjusted OR: 0.27; 95% CI: 0.17-0.43. The protective effect could also be detected through the reduction in the need for and number of doses of exogenous surfactant utilized and the number of days of mechanical ventilation needed for the newborns exposed to antenatal corticosteroids. Their use also reduced the occurrence of intra-hospital deaths (OR: 0.51: 95% CI: 0.38-0.82. However, when adjusted for weight, gestational age, presence of prenatal asphyxia, respiratory distress syndrome, necrotizing enterocolitis and use of mechanical ventilation, the antenatal corticosteroids did not maintain the

  12. Investigating the Conceptual Variation of Major Physics Textbooks

    Science.gov (United States)

    Stewart, John; Campbell, Richard; Clanton, Jessica

    2008-04-01

    The conceptual problem content of the electricity and magnetism chapters of seven major physics textbooks was investigated. The textbooks presented a total of 1600 conceptual electricity and magnetism problems. The solution to each problem was decomposed into its fundamental reasoning steps. These fundamental steps are, then, used to quantify the distribution of conceptual content among the set of topics common to the texts. The variation of the distribution of conceptual coverage within each text is studied. The variation between the major groupings of the textbooks (conceptual, algebra-based, and calculus-based) is also studied. A measure of the conceptual complexity of the problems in each text is presented.

  13. Tiger hair morphology and its variations for wildlife forensic investigation

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    Thitika Kitpipit

    2013-11-01

    Full Text Available Tiger population has dramatically decreased due to illegal consumption and commercialisation of their body parts. Frequently, hair samples are the only evidence found in the crime scene. Thus, they play an important role in species identification for wildlife forensic investigation. In this study, we provide the first in-depth report on a variety of qualitative and quantitative characteristics of tiger guard hairs (24 hairs per individual from four individuals. The proposed method could reduce subjectivity of expert opinions on species identification based on hair morphology. Variations in 23 hair morphological characteristics were quantified at three levels: hair section, body region, and intra-species. The results indicate statistically significant variations in most morphological characteristics in all levels. Intra-species variations of four variables, namely hair length, hair index, scale separation and scale pattern, were low. Therefore, identification of tiger hairs using these multiple features in combination with other characteristics with high inter-species variations (e.g. medulla type should bring about objective and accurate tiger hair identification. The method used should serve as a guideline and be further applied to other species to establish a wildlife hair morphology database. Statistical models could then be constructed to distinguish species and provide evidential values in terms of likelihood ratios.

  14. Intra-Hospital Transport of Patients on Non-Invasive Ventilation: Review, Analysis, and Key Practical Recommendations by the International NIV Committee

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    Annia Schreiber

    2017-12-01

    Full Text Available Intra-hospital transport is often needed for diagnostic and therapeutic procedures that cannot be performed at the bedside. However, moving patients from the safe environment of an Intensive Care Unit (ICU can lead to a variety of complications and adverse events, the risk is even higher in ventilated patients. This review is intended as a guide on how to prevent and avoid these adverse events during intra-hospital transport of patients on non-invasive ventilation (NIV. Greater attention should be paid to NIV indications and the selection of the patients to be transported. Detailed planning, preparation, and communication between the ward of origin and destination site, appropriate equipment, skilled staff, and continuous monitoring are the key major determinants of success in transporting critically ill patients on NIV. These points are discussed and analyzed in detail.

  15. Investigation on generalized Variational Nodal Methods for heterogeneous nodes

    International Nuclear Information System (INIS)

    Wang, Yongping; Wu, Hongchun; Li, Yunzhao; Cao, Liangzhi; Shen, Wei

    2017-01-01

    Highlights: • We developed two heterogeneous nodal methods based on the Variational Nodal Method. • Four problems were solved to evaluate the two heterogeneous nodal methods. • The function expansion method is good at treating continuous-changing heterogeneity. • The finite sub-element method is good at treating discontinuous-changing heterogeneity. - Abstract: The Variational Nodal Method (VNM) is generalized for heterogeneous nodes and applied to four kinds of problems including Molten Salt Reactor (MSR) core problem with continuous cross section profile, Pressurized Water Reactor (PWR) control rod cusping effect problem, PWR whole-core pin-by-pin problem, and heterogeneous PWR core problem without fuel-coolant homogenization in each pin cell. Two approaches have been investigated for the treatment of the nodal heterogeneity in this paper. To concentrate on spatial heterogeneity, diffusion approximation was adopted for the angular variable in neutron transport equation. To provide demonstrative numerical results, the codes in this paper were developed in slab geometry. The first method, named as function expansion (FE) method, expands nodal flux by orthogonal polynomials and the nodal cross sections are also expressed as spatial depended functions. The second path, named as finite sub-element (FS) method, takes advantage of the finite-element method by dividing each node into numbers of homogeneous sub-elements and expanding nodal flux into the combination of linear sub-element trial functions. Numerical tests have been carried out to evaluate the ability of the two nodal (coarse-mesh) heterogeneous VNMs by comparing with the fine-mesh homogeneous VNM. It has been demonstrated that both heterogeneous approaches can handle heterogeneous nodes. The FE method is good at continuous-changing heterogeneity as in the MSR core problem, while the FS method is good at discontinuous-changing heterogeneity such as the PWR pin-by-pin problem and heterogeneous PWR core

  16. an investigation into the applicability of natural load variation

    African Journals Online (AJOL)

    Rev. Anoliefo

    Keywords – impedance matching,energy yield,natural load variation,maximum power ... Wind speed of 1 m/s and absolute air mass of 1.5 are also ... Unfortunately, solar modules operate under ..... thin-film photovoltaic plants by using physical.

  17. Proteogenomic Investigation of Strain Variation in Clinical Mycobacterium tuberculosis Isolates

    KAUST Repository

    Heunis, Tiaan; Dippenaar, Anzaan; Warren, Robin M.; van Helden, Paul D.; van der Merwe, Ruben G.; Gey van Pittius, Nicolaas C.; Pain, Arnab; Sampson, Samantha L.; Tabb, David L.

    2017-01-01

    Mycobacterium tuberculosis consists of a large number of different strains that display unique virulence characteristics. Whole-genome sequencing has revealed substantial genetic diversity among clinical M. tuberculosis isolates, and elucidating the phenotypic variation encoded by this genetic diversity will be of utmost importance to fully understand M. tuberculosis biology and pathogenicity. In this study we integrated whole-genome sequencing and mass spectrometry (GeLC-MS/MS) to reveal strain-specific characteristics in the proteomes of two clinical M. tuberculosis Latin American-Mediterranean isolates. Using this approach we identified 59 peptides containing single amino acid variants, which covered ~9% of all total coding nonsynonymous single nucleotide variants detected by whole-genome sequencing. Furthermore, we identified 29 distinct peptides that mapped to a hypothetical protein not present in the M. tuberculosis H37Rv reference proteome. Here we provide evidence for the expression of this protein in the clinical M. tuberculosis SAWC3651 isolate. The strain-specific databases enabled confirmation of genomic differences (i.e. large genomic regions of difference and nonsynonymous single nucleotide variants) in these two clinical M. tuberculosis isolates and allowed strain differentiation at the proteome level. Our results contribute to the growing field of clinical microbial proteogenomics and can improve our understanding of phenotypic variation in clinical M. tuberculosis isolates.

  18. Proteogenomic Investigation of Strain Variation in Clinical Mycobacterium tuberculosis Isolates

    KAUST Repository

    Heunis, Tiaan

    2017-08-18

    Mycobacterium tuberculosis consists of a large number of different strains that display unique virulence characteristics. Whole-genome sequencing has revealed substantial genetic diversity among clinical M. tuberculosis isolates, and elucidating the phenotypic variation encoded by this genetic diversity will be of utmost importance to fully understand M. tuberculosis biology and pathogenicity. In this study we integrated whole-genome sequencing and mass spectrometry (GeLC-MS/MS) to reveal strain-specific characteristics in the proteomes of two clinical M. tuberculosis Latin American-Mediterranean isolates. Using this approach we identified 59 peptides containing single amino acid variants, which covered ~9% of all total coding nonsynonymous single nucleotide variants detected by whole-genome sequencing. Furthermore, we identified 29 distinct peptides that mapped to a hypothetical protein not present in the M. tuberculosis H37Rv reference proteome. Here we provide evidence for the expression of this protein in the clinical M. tuberculosis SAWC3651 isolate. The strain-specific databases enabled confirmation of genomic differences (i.e. large genomic regions of difference and nonsynonymous single nucleotide variants) in these two clinical M. tuberculosis isolates and allowed strain differentiation at the proteome level. Our results contribute to the growing field of clinical microbial proteogenomics and can improve our understanding of phenotypic variation in clinical M. tuberculosis isolates.

  19. Proteogenomic Investigation of Strain Variation in Clinical Mycobacterium tuberculosis Isolates.

    Science.gov (United States)

    Heunis, Tiaan; Dippenaar, Anzaan; Warren, Robin M; van Helden, Paul D; van der Merwe, Ruben G; Gey van Pittius, Nicolaas C; Pain, Arnab; Sampson, Samantha L; Tabb, David L

    2017-10-06

    Mycobacterium tuberculosis consists of a large number of different strains that display unique virulence characteristics. Whole-genome sequencing has revealed substantial genetic diversity among clinical M. tuberculosis isolates, and elucidating the phenotypic variation encoded by this genetic diversity will be of the utmost importance to fully understand M. tuberculosis biology and pathogenicity. In this study, we integrated whole-genome sequencing and mass spectrometry (GeLC-MS/MS) to reveal strain-specific characteristics in the proteomes of two clinical M. tuberculosis Latin American-Mediterranean isolates. Using this approach, we identified 59 peptides containing single amino acid variants, which covered ∼9% of all coding nonsynonymous single nucleotide variants detected by whole-genome sequencing. Furthermore, we identified 29 distinct peptides that mapped to a hypothetical protein not present in the M. tuberculosis H37Rv reference proteome. Here, we provide evidence for the expression of this protein in the clinical M. tuberculosis SAWC3651 isolate. The strain-specific databases enabled confirmation of genomic differences (i.e., large genomic regions of difference and nonsynonymous single nucleotide variants) in these two clinical M. tuberculosis isolates and allowed strain differentiation at the proteome level. Our results contribute to the growing field of clinical microbial proteogenomics and can improve our understanding of phenotypic variation in clinical M. tuberculosis isolates.

  20. Investigation on Genetic Variation of Iran Watermelon Accession

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    majid reza kiyani

    2009-06-01

    Full Text Available In order to determine of genetic variation in germplasm of 120 watermelon accessions, a field trial conducted at agricultural and natural resource research center of khorasan . These Accessions with four commercial cultivars as control were planted in agnomental design with six replications. 15 quantitative morphological traits were measured and some statistical parameter and analysis include of Mean, Coefficient variance, cluster analysis, correlation regression coefficients were determine for this traits. yield, Sugar percent , time between flowering and ripping, fruit length, fruit width, fruit mass to fruit weight ratio , fruit skin to fruit weight ratio , seed weight to fruit weight ratio , 100 seed weight , seed length , seed diameter , seed width were the most useful traits for identifying of genotypes from each other. A one side analysis of variance was performed for different regions genetic diversity detection, which indicated a significant difference between regions for all traits except fruit Ph and fruit skin thickness. Cluster analysis divided genotypes into eight groups based on quantitative data. Correlation analysis between traits showed a significant relation between yield and all traits except fruit ph, time to flowering and seed fruit length.

  1. Anatomical-clinical investigations of variations of the human coronary arteries

    OpenAIRE

    Aida Hasanović; Faruk Dilberović; Fehim Ovčina

    2003-01-01

    Variations of the human coronary arteries have always attracted the attention of many researchers. A review of the literature shows that variations can cause ischemic heart disease or sudden cardiac death. The aim of the investigations was to examine the existence and clinical significance of variations of the human coronary arteries. Special attention has been focused on myocardial bridging of the coronary arteries and coronary arteriovenous fistula. Our investigations were carried out on th...

  2. Incidence of patient safety events and process-related human failures during intra-hospital transportation of patients: retrospective exploration from the institutional incident reporting system.

    Science.gov (United States)

    Yang, Shu-Hui; Jerng, Jih-Shuin; Chen, Li-Chin; Li, Yu-Tsu; Huang, Hsiao-Fang; Wu, Chao-Ling; Chan, Jing-Yuan; Huang, Szu-Fen; Liang, Huey-Wen; Sun, Jui-Sheng

    2017-11-03

    Intra-hospital transportation (IHT) might compromise patient safety because of different care settings and higher demand on the human operation. Reports regarding the incidence of IHT-related patient safety events and human failures remain limited. To perform a retrospective analysis of IHT-related events, human failures and unsafe acts. A hospital-wide process for the IHT and database from the incident reporting system in a medical centre in Taiwan. All eligible IHT-related patient safety events between January 2010 to December 2015 were included. Incidence rate of IHT-related patient safety events, human failure modes, and types of unsafe acts. There were 206 patient safety events in 2 009 013 IHT sessions (102.5 per 1 000 000 sessions). Most events (n=148, 71.8%) did not involve patient harm, and process events (n=146, 70.9%) were most common. Events at the location of arrival (n=101, 49.0%) were most frequent; this location accounted for 61.0% and 44.2% of events with patient harm and those without harm, respectively (pprocess step was the preparation of the transportation team (n=91, 48.9%). Contributing unsafe acts included perceptual errors (n=14, 7.5%), decision errors (n=56, 30.1%), skill-based errors (n=48, 25.8%), and non-compliance (n=68, 36.6%). Multivariate analysis showed that human failure found in the arrival and hand-off sub-process (OR 4.84, pprocess at the location of arrival and prevent errors other than omissions. Long-term monitoring of IHT-related events is also warranted. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  3. Investigation of switching frequency variations and EMI properties in self-oscillating class D amplifiers

    OpenAIRE

    Nielsen, Dennis; Knott, Arnold; Pfaffinger, Gerhard; Andersen, Michael A. E.

    2009-01-01

    Class D audio amplifiers have gained significant influence in sound reproduction due to their high efficiency. One of the most commonly used control methods in these amplifiers is self-oscillation. A parameter of key interest in self-oscillating amplifiers is the switching frequency, which is known for its variation. Knowledge of switching frequency variations is of great importance with respect to electromagnetic interference (EMI). This paper will investigate, whether the switching frequenc...

  4. Feasibility Study of Ex Ovo Chick Chorioallantoic Artery Model for Investigating Pulsatile Variation of Arterial Geometry.

    Directory of Open Access Journals (Sweden)

    Kweon-Ho Nam

    Full Text Available Despite considerable research efforts on the relationship between arterial geometry and cardiovascular pathology, information is lacking on the pulsatile geometrical variation caused by arterial distensibility and cardiomotility because of the lack of suitable in vivo experimental models and the methodological difficulties in examining the arterial dynamics. We aimed to investigate the feasibility of using a chick embryo system as an experimental model for basic research on the pulsatile variation of arterial geometry. Optical microscope video images of various arterial shapes in chick chorioallantoic circulation were recorded from different locations and different embryo samples. The high optical transparency of the chorioallantoic membrane (CAM allowed clear observation of tiny vessels and their movements. Systolic and diastolic changes in arterial geometry were visualized by detecting the wall boundaries from binary images. Several to hundreds of microns of wall displacement variations were recognized during a pulsatile cycle. The spatial maps of the wall motion harmonics and magnitude ratio of harmonic components were obtained by analyzing the temporal brightness variation at each pixel in sequential grayscale images using spectral analysis techniques. The local variations in the spectral characteristics of the arterial wall motion were reflected well in the analysis results. In addition, mapping the phase angle of the fundamental frequency identified the regional variations in the wall motion directivity and phase shift. Regional variations in wall motion phase angle and fundamental-to-second harmonic ratio were remarkable near the bifurcation area. In summary, wall motion in various arterial geometry including straight, curved and bifurcated shapes was well observed in the CAM artery model, and their local and cyclic variations could be characterized by Fourier and wavelet transforms of the acquired video images. The CAM artery model with

  5. Using of the variational principle for investigation of the supersymmetry models

    International Nuclear Information System (INIS)

    Krasnikov, N.V.

    1985-01-01

    The variational principle is used for investigation of possible spontaneous breaking of supersymmetry. It is shown that if supersymmetry in the generalized Wess-Zumino model is not broken on the classical level, it is neither broken as well with account for quantum corrections

  6. Investigation of Copy Number Variation in Children with Conotruncal Heart Defects

    International Nuclear Information System (INIS)

    Campos, Carla Marques Rondon; Zanardo, Evelin Aline; Dutra, Roberta Lelis; Kulikowski, Leslie Domenici; Kim, Chong Ae

    2015-01-01

    Congenital heart defects (CHD) are the most prevalent group of structural abnormalities at birth and one of the main causes of infant morbidity and mortality. Studies have shown a contribution of the copy number variation in the genesis of cardiac malformations. Investigate gene copy number variation (CNV) in children with conotruncal heart defect. Multiplex ligation-dependent probe amplification (MLPA) was performed in 39 patients with conotruncal heart defect. Clinical and laboratory assessments were conducted in all patients. The parents of the probands who presented abnormal findings were also investigated. Gene copy number variation was detected in 7/39 patients: 22q11.2 deletion, 22q11.2 duplication, 15q11.2 duplication, 20p12.2 duplication, 19p deletion, 15q and 8p23.2 duplication with 10p12.31 duplication. The clinical characteristics were consistent with those reported in the literature associated with the encountered microdeletion/microduplication. None of these changes was inherited from the parents. Our results demonstrate that the technique of MLPA is useful in the investigation of microdeletions and microduplications in conotruncal congenital heart defects. Early diagnosis of the copy number variation in patients with congenital heart defect assists in the prevention of morbidity and decreased mortality in these patients

  7. Investigation of Copy Number Variation in Children with Conotruncal Heart Defects

    Directory of Open Access Journals (Sweden)

    Carla Marques Rondon Campos

    2015-01-01

    Full Text Available Background: Congenital heart defects (CHD are the most prevalent group of structural abnormalities at birth and one of the main causes of infant morbidity and mortality. Studies have shown a contribution of the copy number variation in the genesis of cardiac malformations. Objectives: Investigate gene copy number variation (CNV in children with conotruncal heart defect. Methods: Multiplex ligation-dependent probe amplification (MLPA was performed in 39 patients with conotruncal heart defect. Clinical and laboratory assessments were conducted in all patients. The parents of the probands who presented abnormal findings were also investigated. Results: Gene copy number variation was detected in 7/39 patients: 22q11.2 deletion, 22q11.2 duplication, 15q11.2 duplication, 20p12.2 duplication, 19p deletion, 15q and 8p23.2 duplication with 10p12.31 duplication. The clinical characteristics were consistent with those reported in the literature associated with the encountered microdeletion/microduplication. None of these changes was inherited from the parents. Conclusions: Our results demonstrate that the technique of MLPA is useful in the investigation of microdeletions and microduplications in conotruncal congenital heart defects. Early diagnosis of the copy number variation in patients with congenital heart defect assists in the prevention of morbidity and decreased mortality in these patients.

  8. Investigation of Copy Number Variation in Children with Conotruncal Heart Defects

    Energy Technology Data Exchange (ETDEWEB)

    Campos, Carla Marques Rondon, E-mail: carlamcampos@uol.com.br [Universidade Federal de Mato Grosso, Cuiabá, MT (Brazil); Zanardo, Evelin Aline; Dutra, Roberta Lelis [Departamento de Patologia - Laboratório de Citogenômica - LIM 03 - Universidade de São Paulo, São Paulo, SP (Brazil); Kulikowski, Leslie Domenici [Universidade de São Paulo, São Paulo, SP (Brazil); Departamento de Patologia - Laboratório de Citogenômica - LIM 03 - Universidade de São Paulo, São Paulo, SP (Brazil); Kim, Chong Ae [Universidade de São Paulo, São Paulo, SP (Brazil)

    2015-01-15

    Congenital heart defects (CHD) are the most prevalent group of structural abnormalities at birth and one of the main causes of infant morbidity and mortality. Studies have shown a contribution of the copy number variation in the genesis of cardiac malformations. Investigate gene copy number variation (CNV) in children with conotruncal heart defect. Multiplex ligation-dependent probe amplification (MLPA) was performed in 39 patients with conotruncal heart defect. Clinical and laboratory assessments were conducted in all patients. The parents of the probands who presented abnormal findings were also investigated. Gene copy number variation was detected in 7/39 patients: 22q11.2 deletion, 22q11.2 duplication, 15q11.2 duplication, 20p12.2 duplication, 19p deletion, 15q and 8p23.2 duplication with 10p12.31 duplication. The clinical characteristics were consistent with those reported in the literature associated with the encountered microdeletion/microduplication. None of these changes was inherited from the parents. Our results demonstrate that the technique of MLPA is useful in the investigation of microdeletions and microduplications in conotruncal congenital heart defects. Early diagnosis of the copy number variation in patients with congenital heart defect assists in the prevention of morbidity and decreased mortality in these patients.

  9. Small angle neutron scattering in polyelectrolyte solutions: investigation of polymethacrylic acid solutions by contrast variation method

    International Nuclear Information System (INIS)

    Glavata, D.; Pleshtil, I.; Kunchenko, A.B.; Ostanevich, Yu.M.

    1982-01-01

    Neutron experiments performed by the contrast (background) variation method allows to understand better the role that hydration plays in the study of macromolecules and to draw the connection between the excess scattering amplitude of hydrated molecule with its partial volume. The observed dependence of the compensation point on the degree of neutralization apparently plays an important role in the investigation of polyelectrolytes of biological origin

  10. Investigating variations in implementation fidelity of an organizational-level occupational health intervention.

    Science.gov (United States)

    Augustsson, Hanna; von Thiele Schwarz, Ulrica; Stenfors-Hayes, Terese; Hasson, Henna

    2015-06-01

    The workplace has been suggested as an important arena for health promotion, but little is known about how the organizational setting influences the implementation of interventions. The aims of this study are to evaluate implementation fidelity in an organizational-level occupational health intervention and to investigate possible explanations for variations in fidelity between intervention units. The intervention consisted of an integration of health promotion, occupational health and safety, and a system for continuous improvements (Kaizen) and was conducted in a quasi-experimental design at a Swedish hospital. Implementation fidelity was evaluated with the Conceptual Framework for Implementation Fidelity and implementation factors used to investigate variations in fidelity with the Framework for Evaluating Organizational-level Interventions. A multi-method approach including interviews, Kaizen notes, and questionnaires was applied. Implementation fidelity differed between units even though the intervention was introduced and supported in the same way. Important differences in all elements proposed in the model for evaluating organizational-level interventions, i.e., context, intervention, and mental models, were found to explain the differences in fidelity. Implementation strategies may need to be adapted depending on the local context. Implementation fidelity, as well as pre-intervention implementation elements, is likely to affect the implementation success and needs to be assessed in intervention research. The high variation in fidelity across the units indicates the need for adjustments to the type of designs used to assess the effects of interventions. Thus, rather than using designs that aim to control variation, it may be necessary to use those that aim at exploring and explaining variation, such as adapted study designs.

  11. Data-driven Inference and Investigation of Thermosphere Dynamics and Variations

    Science.gov (United States)

    Mehta, P. M.; Linares, R.

    2017-12-01

    This paper presents a methodology for data-driven inference and investigation of thermosphere dynamics and variations. The approach uses data-driven modal analysis to extract the most energetic modes of variations for neutral thermospheric species using proper orthogonal decomposition, where the time-independent modes or basis represent the dynamics and the time-depedent coefficients or amplitudes represent the model parameters. The data-driven modal analysis approach combined with sparse, discrete observations is used to infer amplitues for the dynamic modes and to calibrate the energy content of the system. In this work, two different data-types, namely the number density measurements from TIMED/GUVI and the mass density measurements from CHAMP/GRACE are simultaneously ingested for an accurate and self-consistent specification of the thermosphere. The assimilation process is achieved with a non-linear least squares solver and allows estimation/tuning of the model parameters or amplitudes rather than the driver. In this work, we use the Naval Research Lab's MSIS model to derive the most energetic modes for six different species, He, O, N2, O2, H, and N. We examine the dominant drivers of variations for helium in MSIS and observe that seasonal latitudinal variation accounts for about 80% of the dynamic energy with a strong preference of helium for the winter hemisphere. We also observe enhanced helium presence near the poles at GRACE altitudes during periods of low solar activity (Feb 2007) as previously deduced. We will also examine the storm-time response of helium derived from observations. The results are expected to be useful in tuning/calibration of the physics-based models.

  12. Investigation into Variations of Welding Residual Stresses and Redistribution Behaviors for Different Repair Welding Widths

    International Nuclear Information System (INIS)

    Park, Chiyong; Lee, Hweesueng; Huh, Namsu

    2014-01-01

    In this study, we investigated the variations in welding residual stresses in dissimilar metal butt weld due to width of repair welding and re-distribution behaviors resulting from similar metal welding (SMW) and mechanical loading. To this end, detailed two-dimensional axi-symmetric finite element (FE) analyses were performed considering five different repair welding widths. Based on the FE results, we first evaluated the welding residual stress distributions in repair welding. We then investigated the re-distribution behaviors of the residual stresses due to SMW and mechanical loads. It is revealed that large tensile welding residual stresses take place in the inner surface and that its distribution is affected, provided repair welding width is larger than certain value. The welding residual stresses resulting from repair welding are remarkably reduced due to SMW and mechanical loading, regardless of the width of the repair welding

  13. Investigation of dimensional variation in parts manufactured by fused deposition modeling using Gauge Repeatability and Reproducibility

    Science.gov (United States)

    Mohamed, Omar Ahmed; Hasan Masood, Syed; Lal Bhowmik, Jahar

    2018-02-01

    In the additive manufacturing (AM) market, the question is raised by industry and AM users on how reproducible and repeatable the fused deposition modeling (FDM) process is in providing good dimensional accuracy. This paper aims to investigate and evaluate the repeatability and reproducibility of the FDM process through a systematic approach to answer this frequently asked question. A case study based on the statistical gage repeatability and reproducibility (gage R&R) technique is proposed to investigate the dimensional variations in the printed parts of the FDM process. After running the simulation and analysis of the data, the FDM process capability is evaluated, which would help the industry for better understanding the performance of FDM technology.

  14. Variations in GPs' decisions to investigate suspected lung cancer: a factorial experiment using multimedia vignettes.

    Science.gov (United States)

    Sheringham, Jessica; Sequeira, Rachel; Myles, Jonathan; Hamilton, William; McDonnell, Joe; Offman, Judith; Duffy, Stephen; Raine, Rosalind

    2017-06-01

    Lung cancer survival is low and comparatively poor in the UK. Patients with symptoms suggestive of lung cancer commonly consult primary care, but it is unclear how general practitioners (GPs) distinguish which patients require further investigation. This study examined how patients' clinical and sociodemographic characteristics influence GPs' decisions to initiate lung cancer investigations. A factorial experiment was conducted among a national sample of 227 English GPs using vignettes presented as simulated consultations. A multimedia-interactive website simulated key features of consultations using actors ('patients'). GP participants made management decisions online for six 'patients', whose sociodemographic characteristics systematically varied across three levels of cancer risk. In low-risk vignettes, investigation (ie, chest X-ray ordered, computerised tomography scan or respiratory consultant referral) was not indicated; in medium-risk vignettes, investigation could be appropriate; in high-risk vignettes, investigation was definitely indicated. Each 'patient' had two lung cancer-related symptoms: one volunteered and another elicited if GPs asked. Variations in investigation likelihood were examined using multilevel logistic regression. GPs decided to investigate lung cancer in 74% (1000/1348) of vignettes. Investigation likelihood did not increase with cancer risk. Investigations were more likely when GPs requested information on symptoms that 'patients' had but did not volunteer (adjusted OR (AOR)=3.18; 95% CI 2.27 to 4.70). However, GPs omitted to seek this information in 42% (570/1348) of cases. GPs were less likely to investigate older than younger 'patients' (AOR=0.52; 95% CI 0.39 to 0.7) and black 'patients' than white (AOR=0.68; 95% CI 0.48 to 0.95). GPs were not more likely to investigate 'patients' with high-risk than low-risk cancer symptoms. Furthermore, they did not investigate everyone with the same symptoms equally. Insufficient data gathering

  15. Surgical amputation of the digit: an investigation into the technical variations among hand surgeons.

    Science.gov (United States)

    Li, Andrew; Meunier, Matthew; Rennekampff, Hans-Oliver; Tenenhaus, Mayer

    2013-01-01

    Digital injuries are common and frequently complicate occupational hazards and trauma. The management of these injuries often necessitates digital amputation, and a variety of different amputation techniques are advocated and employed by hand surgeons. In this survey study, we investigate the variation in technical detail among a group of hand surgeons when performing digital amputations, specifically the preferred management of the residual articular cartilage, transected nerves, and phalangeal contouring. We reviewed the literature on techniques in digital amputation and created a 7-question survey that targeted controversial issues within this specific topic. We then sent this survey electronically to the members of the American Society for Surgery of the Hand and reviewed the responses of the respondents (n = 592, 20%). There was a mixed response regarding whether or not to remove the articular cartilage when disarticulating, nearly a 50% split between the respondents. Most would perform a "pull and resect" technique for transected nerves. Phalangeal contouring was generally agreed upon, though the technique in doing so varied from performing condylectomies, to bony contouring only, to some combination of both. We detected a substantial variation in technique among our group of hand surgeons regarding the treatment of articular cartilage and the method of phalangeal contouring. There was more consensus regarding the treatment of transected nerve. It is interesting that to date, the aforementioned issues in digital amputation have not been critically evaluated by definitive and well-controlled studies.

  16. A preliminary investigation into the genetic variation and population structure of Taenia hydatigena from Sardinia, Italy.

    Science.gov (United States)

    Boufana, Belgees; Scala, Antonio; Lahmar, Samia; Pointing, Steve; Craig, Philip S; Dessì, Giorgia; Zidda, Antonella; Pipia, Anna Paola; Varcasia, Antonio

    2015-11-30

    Cysticercosis caused by the metacestode stage of Taenia hydatigena is endemic in Sardinia. Information on the genetic variation of this parasite is important for epidemiological studies and implementation of control programs. Using two mitochondrial genes, the cytochrome c oxidase subunit 1 (cox1) and the NADH dehydrogenase subunit 1 (ND1) we investigated the genetic variation and population structure of Cysticercus tenuicollis from Sardinian intermediate hosts and compared it to that from other hosts from various geographical regions. The parsimony cox1 network analysis indicated the existence of a common lineage for T. hydatigena and the overall diversity and neutrality indices indicated demographic expansion. Using the cox1 sequences, low pairwise fixation index (Fst) values were recorded for Sardinian, Iranian and Palestinian sheep C. tenuicollis which suggested the absence of genetic differentiation. Using the ND1 sequences, C. tenuicollis from Sardinian sheep appeared to be differentiated from those of goat and pig origin. In addition, goat C. tenuicollis were genetically different from adult T. hydatigena as indicated by the statistically significant Fst value. Our results are consistent with biochemical and morphological studies that suggest the existence of variants of T. hydatigena. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Investigation of the daily variation in iodine and creatinine excretion in human urine

    International Nuclear Information System (INIS)

    Aabech, H.S.

    1975-08-01

    Continuing earlier investigations of the level of iodine intake in Norway, the excretion of iodine in 24-hour samples of urine over 7 days has been measured for 23 persons. Three of them collected 24-hour samples of urine during continuous periods of 21, 22 and 54 days. The main aim of the investigation was to study the diurnal variation of iodine excretion , and to correlate it with diet components when connection was suspected. To this end the persons had to keep record of the diet, especially with respect to fish and fish products. The variation from day to day of the iodine excretion was much greater than expected, and the highest values were always preceded by meals of sea-fish. Mean 24-hour iodine excretion from 13 males was 266 μg/24h (range 54-2272), from 8 females 154 μg/24h (range 58-627), and from 2 children 74 μg/24h (range 33-129). Large fluctuations were present, as indicated by standard deviations that varied from 12 to 119% of the mean. None of the persons had a mean 24-hour excretion lower than the advised minimum of 1 μg iodine/kg b w. The excretion of creatinine has also been measured, and the excretion from day to day showed large fluctuations for some of the persons. In 13 males the mean 24-hour excretion of creatinine was 1.88 gram (range 0.81-2.93), and in 8 females 1.17 gram (range 0.47-1.74). In one person, who collected urine during a period of 54 days, the mean excretion of creatinine was 1.80 gram (range 1.19-2.75). (auth.)

  18. Investigations of radioactivity level variations in Armenia after the Chernobyl accident

    International Nuclear Information System (INIS)

    Nalbandyan, A.

    2006-01-01

    The problem of radioactive pollution of biosphere has been acquiring a special topicality after nuclear weapon testing and NPP-induced accidents that have already brought to global pollution of the Earth with radioactive substances. One of visual examples of regional radioactive pollution is dispersion of emissions all over the territory of Central Europe after the Chernobyl accident, which aftermaths impacted Armenia, as well. Monitoring investigations in the Ararat Valley showed a precise peak of gross radioactivity of atmospheric fallout in 1986 - the year of Chernobyl accident. Gross mean annual radioactivity was established 1783 10 7 Bq/KXm 2 yr. Later, a sharp fall in the activity was observed. Mostly, radioactive fallout consisted of short-lived radionuclides. Measurements for 1986-1987 showed that gross β-radioactivity level in soils amounted to 977-1022 Bq/KXg, repeated measurements in 1991 allowed establishing 640-656 Bq/KXg. A precise indicator of radioactive emissions that reached Armenia after the Chernobyl accident was a short-lived radionuclide 134 Cs (T 1 /2=2.07 yr) identified in soils. Measurements made 2 years later showed half as much decay of 134 Cs, and in some points established were its traces only. 137 Cs/134 Cs ratio in varied 1.4 to 1.8 in atmospheric fallout and 2.1 to 33.4 in soils. Thus, monitoring investigations evidence a regional character of Chernobyl emission dispersion, this being proved by investigations of radioactivity level variations in Armenia, too

  19. Investigating output and energy variations and their relationship to delivery QA results using Statistical Process Control for helical tomotherapy.

    Science.gov (United States)

    Binny, Diana; Mezzenga, Emilio; Lancaster, Craig M; Trapp, Jamie V; Kairn, Tanya; Crowe, Scott B

    2017-06-01

    The aims of this study were to investigate machine beam parameters using the TomoTherapy quality assurance (TQA) tool, establish a correlation to patient delivery quality assurance results and to evaluate the relationship between energy variations detected using different TQA modules. TQA daily measurement results from two treatment machines for periods of up to 4years were acquired. Analyses of beam quality, helical and static output variations were made. Variations from planned dose were also analysed using Statistical Process Control (SPC) technique and their relationship to output trends were studied. Energy variations appeared to be one of the contributing factors to delivery output dose seen in the analysis. Ion chamber measurements were reliable indicators of energy and output variations and were linear with patient dose verifications. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

  20. AN INVESTIGATION OF THE VARIATION OF PORE STRUCTURE IN EUCALYPTUS FIBRE DURING RECYCLING

    Directory of Open Access Journals (Sweden)

    Wen Jie Guo

    2011-04-01

    Full Text Available Variation in the pore structure of eucalyptus fibre during recycling was investigated using low-temperature nitrogen adsorption, atomic force microscopy (AFM, and fractal geometry. The Brunauer- Emmett-Teller (BET surface area of the fibre fell to 55.1% of the original value after the first cycle, and to 49.0% after the second cycle, ultimately declining to 35.0% after the fourth. The Barret-Joyner- Halenda (BJH adsorption cumulative pore volume fell to 38.4% of the original by the fourth. After four cycles, the average pore diameter fell to 82% of the original. AFM tests showed that the pore structure in fibre expressed high self-similarity in statistics, and the pore structure in the fibre could be regarded as a fractal. Fractal geometry analysis of the results showed that the fractal dimension of eucalyptus virgin fibre is 2.954. With the number of process cycles increasing, the fractal dimension fell to a minimum of 2.886 after four cycles. The water retention value (WRV of the fibre was proportional to the fractal dimension and the crystallinity of fibre.

  1. Investigation variation of carbon dioxide based on GOSAT data in peninsular Malaysia

    Science.gov (United States)

    Sim, C. K.; Lim, H. S.; MatJafri, M. Z.

    2015-10-01

    Carbon dioxide (CO2) is an inodorous and transparent gas, and naturally originates in our atmosphere. Due to its optical characteristics, CO2 is the most important greenhouse gas and play a key role in climate change due to an effective thermal infrared (IR) radiation absorber. Satellite observations of atmospheric carbon dioxide (CO2) can significantly improve our knowledge about the sources and sinks of CO2. The remote sensing satellite, namely Greenhouse Gases Observing Satellite (GOSAT) was employed to investigate the spatial and variations of CO2 column-averaged dry airmole fractions, denoted XCO2 over Peninsular Malaysia from January 2013 to December 2013. The analysis of CO2 in the study area shows the significant differences between northeast monsoon (NEM) and the southwest monsoon (SWM). During NEM season, cold air outbreaks from Siberia spreads to equatorial region in the form of north-easterly cold surge winds and associated with a low-level anticyclone over Southeast Asia. Inversely, air masses from the southwest contribute to long-range air pollution due to transportation of atmospheric CO2 by wind is associated with biomass burning in Sumatra, Indonesia. The GOSAT data and the Satellite measurements are able to measure the increase of the atmosphere CO2 values over different regions.

  2. Investigation of the spatial generalization of Kato's theorem by a variational density-functional approach

    International Nuclear Information System (INIS)

    Csavinszky, P.

    1990-01-01

    In a recent work, March has considered the quantum-mechanical system of an arbitrary number of closed electronic shells around an atomic nucleus of charge Z a e. March has assumed that the shells are filled by noninteracting electrons, moving in the bare Coulomb potential energy of V(r) = -Z a e 2 /r. In this framework, the basic quantity is the total electron (number) density ρ(r), built by summing the (number) density ρ n (r) of the nth closed electronic shell over the principal quantum number n. March has shown that Kato's theorem, (∂ρ(r)/∂r) r=0 = -(2Z a /a 0 )ρ (r = 0), with a 0 = ℎ 2 /me 2 , is amenable to a spatially dependent generalization that can be expressed by ∂ρ(r)/∂r = -(2Z a /a 0 )ρ s (r), where ρ s (r) is the s-state contribution from the n closed electronic shells to ρ(r). The present work investigates the spatially dependent generalization of Kato's theorem for the Ne atom by making use of a variational density-functional approach and adopting several expressions for the kinetic-energy functional of the electrons. The intriguing question of identifying the best kinetic-energy functional is raised and discussed

  3. Experimental investigation on variation of physical properties of coal samples subjected to microwave irradiation

    Science.gov (United States)

    Hu, Guozhong; Yang, Nan; Xu, Guang; Xu, Jialin

    2018-03-01

    The gas drainage rate of low-permeability coal seam is generally less than satisfactory. This leads to the gas disaster of coal mine, and largely restricts the extraction of coalbed methane (CBM), and increases the emission of greenhouse gases in the mining area. Consequently, enhancing the gas drainage rate is an urgent challenge. To solve this problem, a new approach of using microwave irradiation (MWR) as a non-contact physical field excitation method to enhance gas drainage has been attempted. In order to evaluate the feasibility of this method, the methane adsorption, diffusion and penetrability of coal subjected to MWR were experimentally investigated. The variation of methane adsorbed amount, methane diffusion speed and absorption loop for the coal sample before and after MWR were obtained. The findings show that the MWR can change the adsorption property and reduce the methane adsorption capacity of coal. Moreover, the methane diffusion characteristic curves for both the irradiated coal samples and theoriginal coal samples present the same trend. The irradiated coal samples have better methane diffusion ability than the original ones. As the adsorbed methane decreases, the methane diffusion speed increases or remain the same for the sample subjected to MWR. Furthermore, compared to the original coal samples, the area of the absorption loop for irradiated samples increases, especially for the micro-pore and medium-pore stage. This leads to the increase of open pores in the coal, thus improving the gas penetrability of coal. This study provides supports for positive MWR effects on changing the methane adsorption and improving the methane diffusion and the gas penetrability properties of coal samples.

  4. Investigation of variations and trends in solar radiation in Klang Valley Region, Malaysia

    International Nuclear Information System (INIS)

    Mohamed Elnour Yassen, Jamaluddin Mohd Jahi

    2006-01-01

    The objective of this study is to investigate variations and trends in the global solar radiation in Klang Valley region. The least square method was used for the trend analysis. Since the available time series covers 27 years, linear regression was preferred for the trend analysis. The linear trend is used mainly to test the change in solar radiation and to set limits on the rate of change. Trend line and values and significance levels of the slopes have been found. The seasonal and the annual average values were computed from the monthly average radiation data. The seasonal and annual average solar radiation values were designated as dependent variables, and thus, were fitted linearly for season and annual means for each station. The results showed that the mean of maximum incoming global radiation in Sepember with a value of 21.1 MJ m-2 at Petaling Jaya, while the mean minimum in November and December with values of 10.7 and 10.9 MJ m-2 at Petaling Jaya. The low amounts of solar radiation received in November and December are due to greater cloudiness during the period coinciding with the northeast monsoon season. On rainy days, very little global solar radiation received in November and December are due to greater cloudiness during the period coinciding with the northeast monsoon season. On rainy days, very little global solar radiation is received. The distribution of the seasonal mean values of solar radiation exhibits a high symmetry. Inter-monsoon seasons (April-May) and (October-November) show a similar behavior, just like the northeast monsoon season. The overall average rate of change in global solar radiation during 1975-2002 and 1977-2000 is represented by the slope of the linear regression was small (-0.126 and -0.314 MJ m-2 per year for Subang Airport and Petaling Jaya respectively)

  5. A genome-wide investigation of copy number variation in patients with sporadic brain arteriovenous malformation.

    Directory of Open Access Journals (Sweden)

    Nasrine Bendjilali

    Full Text Available Brain arteriovenous malformations (BAVM are clusters of abnormal blood vessels, with shunting of blood from the arterial to venous circulation and a high risk of rupture and intracranial hemorrhage. Most BAVMs are sporadic, but also occur in patients with Hereditary Hemorrhagic Telangiectasia, a Mendelian disorder caused by mutations in genes in the transforming growth factor beta (TGFβ signaling pathway.To investigate whether copy number variations (CNVs contribute to risk of sporadic BAVM, we performed a genome-wide association study in 371 sporadic BAVM cases and 563 healthy controls, all Caucasian. Cases and controls were genotyped using the Affymetrix 6.0 array. CNVs were called using the PennCNV and Birdsuite algorithms and analyzed via segment-based and gene-based approaches. Common and rare CNVs were evaluated for association with BAVM.A CNV region on 1p36.13, containing the neuroblastoma breakpoint family, member 1 gene (NBPF1, was significantly enriched with duplications in BAVM cases compared to controls (P = 2.2×10(-9; NBPF1 was also significantly associated with BAVM in gene-based analysis using both PennCNV and Birdsuite. We experimentally validated the 1p36.13 duplication; however, the association did not replicate in an independent cohort of 184 sporadic BAVM cases and 182 controls (OR = 0.81, P = 0.8. Rare CNV analysis did not identify genes significantly associated with BAVM.We did not identify common CNVs associated with sporadic BAVM that replicated in an independent cohort. Replication in larger cohorts is required to elucidate the possible role of common or rare CNVs in BAVM pathogenesis.

  6. Variation in Direct Access to Tests to Investigate Cancer: A Survey of English General Practitioners.

    Directory of Open Access Journals (Sweden)

    Brian D Nicholson

    Full Text Available The 2015 NICE guidelines for suspected cancer recommend that English General Practitioners have direct access to diagnostic tests to investigate symptoms of cancer that do not meet the criteria for urgent referral. We aimed to identify the proportion of GPs in England with direct access to these tests.We recruited 533 English GPs through a national clinical research network to complete an online survey about direct access to laboratory, radiology, and endoscopy tests in the three months leading up to the release of the 2015 NICE guidance. If they had direct access to a diagnostic test, GPs were asked about the time necessary to arrange a test and receive a report. Results are reported by NHS sub-region and, adjusting for sampling, for England as a whole.Almost all GPs reported direct access to x-ray and laboratory investigations except faecal occult blood testing (54%, 95% CI 49-59% and urine protein electrophoresis (89%, 95% CI 84-92%. Fewer GPs had direct access to CT scans (54%, 95% CI 49-59% or endoscopy (colonoscopy 32%, 95% CI 28-37%; gastroscopy 72%, 95% CI 67-77%. There was significant variation in direct access between NHS regions for the majority of imaging tests-for example, from 20 to 85% to MRI. Apart from x-ray, very few GPs (1-22% could access radiology and endoscopy within the timescales recommended by NICE. The modal request to test time was 2-4 weeks for routine radiology and 4-6 weeks for routine endoscopy with results taking another 1-2 weeks.At the time that the 2015 NICE guideline was released, local investment was required to not only provide direct access but also reduce the interval between request and test and speed up reporting. Further research using our data as a benchmark is now required to identify whether local improvements in direct access have been achieved in response to the NICE targets. If alternative approaches to test access are to be proposed they must be piloted comprehensively and underpinned by robust

  7. Variation in Direct Access to Tests to Investigate Cancer: A Survey of English General Practitioners

    Science.gov (United States)

    Nicholson, Brian D.; Oke, Jason L.; Rose, Peter W.; Mant, David

    2016-01-01

    Background The 2015 NICE guidelines for suspected cancer recommend that English General Practitioners have direct access to diagnostic tests to investigate symptoms of cancer that do not meet the criteria for urgent referral. We aimed to identify the proportion of GPs in England with direct access to these tests. Methods We recruited 533 English GPs through a national clinical research network to complete an online survey about direct access to laboratory, radiology, and endoscopy tests in the three months leading up to the release of the 2015 NICE guidance. If they had direct access to a diagnostic test, GPs were asked about the time necessary to arrange a test and receive a report. Results are reported by NHS sub-region and, adjusting for sampling, for England as a whole. Results Almost all GPs reported direct access to x-ray and laboratory investigations except faecal occult blood testing (54%, 95% CI 49–59%) and urine protein electrophoresis (89%, 95% CI 84–92%). Fewer GPs had direct access to CT scans (54%, 95% CI 49–59%) or endoscopy (colonoscopy 32%, 95% CI 28–37%; gastroscopy 72%, 95% CI 67–77%). There was significant variation in direct access between NHS regions for the majority of imaging tests—for example, from 20 to 85% to MRI. Apart from x-ray, very few GPs (1–22%) could access radiology and endoscopy within the timescales recommended by NICE. The modal request to test time was 2–4 weeks for routine radiology and 4–6 weeks for routine endoscopy with results taking another 1–2 weeks. Conclusion At the time that the 2015 NICE guideline was released, local investment was required to not only provide direct access but also reduce the interval between request and test and speed up reporting. Further research using our data as a benchmark is now required to identify whether local improvements in direct access have been achieved in response to the NICE targets. If alternative approaches to test access are to be proposed they must be

  8. Emotional voice processing: investigating the role of genetic variation in the serotonin transporter across development.

    Directory of Open Access Journals (Sweden)

    Tobias Grossmann

    Full Text Available The ability to effectively respond to emotional information carried in the human voice plays a pivotal role for social interactions. We examined how genetic factors, especially the serotonin transporter genetic variation (5-HTTLPR, affect the neurodynamics of emotional voice processing in infants and adults by measuring event-related brain potentials (ERPs. The results revealed that infants distinguish between emotions during an early perceptual processing stage, whereas adults recognize and evaluate the meaning of emotions during later semantic processing stages. While infants do discriminate between emotions, only in adults was genetic variation associated with neurophysiological differences in how positive and negative emotions are processed in the brain. This suggests that genetic association with neurocognitive functions emerges during development, emphasizing the role that variation in serotonin plays in the maturation of brain systems involved in emotion recognition.

  9. Patient dose variation investigated in four Irish hospitals for barium meal and barium enema examinations

    International Nuclear Information System (INIS)

    Carroll, E.; Brennan, P.C.

    2001-01-01

    Four hospitals have been studied, intra- and inter-hospital variations examined and the mean DAP values recorded for barium enemas and barium meals. Mean DAP values for barium meals and barium enemas at 11.4 Gy.cm 2 and 20.1 Gy.cm 2 respectively have been shown. Differences between individual examinations for barium meals varied by up to a factor of 185 and for barium enemas, up to a factor of 19, with hospital means for barium meal and enema examinations each differing by up to a factor of 3. The data provided by this study have suggested that large variations in patient dose do exist in Ireland for barium meal and barium enema examinations. Fluoroscopy time was shown to be a major contributor to the variations reported, with number of images playing a minor role. Results have demonstrated the need for standardisation of technique throughout the country for these examinations. (author)

  10. Investigating the variations in survival rates for very preterm infants in 10 European regions : the MOSAIC birth cohort

    NARCIS (Netherlands)

    Draper, E. S.; Zeitlin, J.; Fenton, A. C.; Weber, T.; Gerrits, J.; Martens, G.; Misselwitz, B.; Breart, G.

    Objective: To investigate the variation in the survival rate and the mortality rates for very preterm infants across Europe. Design: A prospective birth cohort of very preterm infants for 10 geographically defined European regions during 2003, followed to discharge home from hospital. Participants:

  11. Investigation on seasonal variation of thermal-induced strain in flexible pavements based on field and laboratory measurements

    Directory of Open Access Journals (Sweden)

    Simita Biswas

    2016-09-01

    Full Text Available Pavement temperature variation has a large influence on the structural response of flexible pavements. Daily and seasonal temperature fluctuation causes expansion and contraction of pavement material, which then leads to the generation of thermal strain. In this study, field observation and laboratory tests were conducted to investigate seasonal variation of thermal-induced strain in flexible pavement. Field observations were conducted at the Integrated Road Research Facility (IRRF’s test road in Edmonton, Alberta, Canada, which is fully equipped with structural and environmental monitoring instruments. The main objective of the field study was to compare the variation of thermal-induced strain in warm and cold seasons. Field results indicated that thermal-induced strain is 1.4–2.0 times greater in cold seasons than in warm seasons following the same pavement temperature variations; however, strain generation rate was greater in warm seasons. Laboratory testing of asphalt slab and cylindrical samples produced comparable ratios. Moreover, field observation and laboratory testing showed a similar trend of temperature and thermal strain variations. Keywords: Thermal-induced strain, Asphalt strain gauge, Field observation, Flexible pavement, Laboratory testing, Seasonal variation

  12. Autoradiographic investigations on the question of diurnal variations of cell proliferation in the jejunal crypt epithelia of mice

    International Nuclear Information System (INIS)

    Herterich, G.C.

    1982-01-01

    In this work the question was investigated whether the proliferation activity of the crypt epithelia of the small intestine of mice is subject to diurnal variations. The results published so far to settle this question are contradictory. The flow rate at the beginning and end of the S phase was measured as a function of daytime for the jejunal crypt epithelia of mice following a double labelling with 3-H and 14-C-TdR. The quotient of the cell flow rate in and out of the S phase is supposed to be = 1 over the whole day if there are no diurnal variations. The method of measurements of the cell flow rate was chosen above all because the quotient is largely independent of the variation from animal to animal. The experiments provided dues as to the presence of deviations of the quotient of cell flow rate at the end and beginning of the S phase and of the mitotic index from the daily mean value. However, on account of the relatively large statistical variations of the values at the different daytimes it is not possible to state clearly whether the cell proliferation of the jejunal epithelium is subject to diurnal variations. Should there be such variations, then they are not large at any rate. (orig./MG) [de

  13. Investigation of microbial adaptation to salinity variation for treatment of reverse osmosis concentrate by membrane bioreactor

    DEFF Research Database (Denmark)

    Jang, Duksoo; Moon, Chungman; Ahn, Kyuhong

    2014-01-01

    quantitative study on a microbial adaptation strategy for variations on salt concentration (0–20 g/L), lab-scale membrane bioreactors (7L working volume) with polypropylene hollow fiber membrane module (pore size 0.4 μm) were used with different adaptation strategies: instant and stepwise mode. The performance...

  14. Investigation of Spatial Variation of Sea States Offshore of Humboldt Bay CA Using a Hindcast Model.

    Energy Technology Data Exchange (ETDEWEB)

    Dallman, Ann Renee; Neary, Vincent Sinclair

    2014-10-01

    Spatial variability of sea states is an important consideration when performing wave resource assessments and wave resource characterization studies for wave energy converter (WEC) test sites and commercial WEC deployments. This report examines the spatial variation of sea states offshore of Humboldt Bay, CA, using the wave model SWAN . The effect of depth and shoaling on bulk wave parameters is well resolved using the model SWAN with a 200 m grid. At this site, the degree of spatial variation of these bulk wave parameters, with shoaling generally perpendicular to the depth contours, is found to depend on the season. The variation in wave height , for example, was higher in the summer due to the wind and wave sheltering from the protruding land on the coastline north of the model domain. Ho wever, the spatial variation within an area of a potential Tier 1 WEC test site at 45 m depth and 1 square nautical mile is almost negligible; at most about 0.1 m in both winter and summer. The six wave characterization parameters recommended by the IEC 6 2600 - 101 TS were compared at several points along a line perpendicular to shore from the WEC test site . As expected, these parameters varied based on depth , but showed very similar seasonal trends.

  15. A framework for investigating geographical variation in diseases, based on a study of Legionnaires' disease.

    Science.gov (United States)

    Bhopal, R S

    1991-11-01

    Demonstration of geographical variations in disease can yield powerful insight into the disease pathway, particularly for environmentally acquired conditions, but only if the many problems of data interpretation can be solved. This paper presents the framework, methods and principles guiding a study of the geographical epidemiology of Legionnaires' Disease in Scotland. A case-list was constructed and disease incidence rates were calculated by geographical area; these showed variation. Five categories of explanation for the variation were identified: short-term fluctuations of incidence in time masquerading as differences by place; artefact; and differences in host-susceptibility, agent virulence, or environment. The methods used to study these explanations, excepting agent virulence, are described, with an emphasis on the use of previously existing data to test hypotheses. Examples include the use of mortality, census and hospital morbidity data to assess the artefact and host-susceptibility explanations; and the use of ratios of serology tests to disease to examine the differential testing hypothesis. The reasoning and process by which the environmental focus of the study was narrowed and the technique for relating the geographical pattern of disease to the putative source are outlined. This framework allows the researcher to plan for the parallel collection of the data necessary both to demonstrate geographical variation and to point to the likely explanation.

  16. INVESTIGATION OF b-VALUE VARIATIONS IN THE AFRICAN AND PARTS OF EURASIAN PLATES

    Directory of Open Access Journals (Sweden)

    Awoyemi, M. O.

    2017-06-01

    Full Text Available Numerous earthquakes have occurred along the collision zones of the African and parts of Eurasian plates. Some of these earthquakes along these zones have generated tsunamis. To mitigate this hazard, knowledge of b-values of the Gutenberg – Richter relation for tectonic earthquakes in the African and parts of Eurasian plates is essential. The temporal variations of b-values were evaluated using sliding time windows with each window containing a total of 100 events with a view to utilizing the results as a precursor for the earthquake occurrence. The spatial variation of b-values of the study area was also delineated by dividing it into grids and calculating the b-values for each grid using constant radius and constant number of events. Results obtained from the temporal variation of b-values showed that earthquakes of large magnitudes occurred when the b-values were low while earthquakes of small magnitudes occurred when the b-values were high throughout the study period. The results of the spatial distribution of b-values also showed that earthquakes of large magnitudes occurred in areas of low b-values while earthquakes of small magnitudes occurred in areas of high b-values. The study therefore concluded that the temporal and spatial variations of b-values might be considered as a precursor for earthquake prediction.

  17. An investigation into the relationship between thickness variations and manufacturing techniques of mouthguards.

    Science.gov (United States)

    Farrington, Timothy; Coward, Trevor; Onambele-Pearson, Gladys; Taylor, Rebecca L; Earl, Philip; Winwood, Keith

    2016-02-01

    The aim of this study was to measure the finished thickness of a single identical 4-mm EVA mouthguard model from a large fabricated sample group and to evaluate the degree of material thinning and variations during the fabrication process. Twenty boxes were distributed to dental technician participants, each containing five duplicated dental models (n = 100), alongside 5 × 4 mm mouthguard blanks and a questionnaire. The mouthguards were measured using electronic callipers (resolution: ±0.01 mm) at three specific points. The five thickest and thinnest mouthguards were examined using a CT scanner to describe the surface typography unique to each mouthguard, highlighting dimensional thinning patterns during the fabrication process. Of the three measurement points, the anterior sulcus point of the mouthguard showed a significant degree of variation (up to 34% coefficient of variation), in finished mouthguard thickness between individuals. The mean thickness of the mouthguards in the anterior region was 1.62 ± 0.38 mm with a range of 0.77-2.80 mm. This variation was also evident in the occlusion and posterior lingual regions but to a lesser extent (up to 12.2% and 9.8% variations, respectively). This study highlights variability in the finished thickness of the mouthguards especially in the anterior sulcus region measurement point, both within and between individuals. At the anterior region measurement point of the mouthguard, the mean thickness was 1.62 mm, equating to an overall material thinning of 59.5% when using a single 4-mm EVA blank. This degree of thinning is comparative to previous single operator research studies. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  18. Rapid core field variations during the satellite era: Investigations using stochastic process based field models

    DEFF Research Database (Denmark)

    Finlay, Chris; Olsen, Nils; Gillet, Nicolas

    We present a new ensemble of time-dependent magnetic field models constructed from satellite and observatory data spanning 1997-2013 that are compatible with prior information concerning the temporal spectrum of core field variations. These models allow sharper field changes compared to tradition...... physical hypotheses can be tested by asking questions of the entire ensemble of core field models, rather than by interpreting any single model.......We present a new ensemble of time-dependent magnetic field models constructed from satellite and observatory data spanning 1997-2013 that are compatible with prior information concerning the temporal spectrum of core field variations. These models allow sharper field changes compared to traditional...... regularization methods based on minimizing the square of second or third time derivative. We invert satellite and observatory data directly by adopting the external field and crustal field modelling framework of the CHAOS model, but apply the stochastic process method of Gillet et al. (2013) to the core field...

  19. SU-E-T-636: Investigation of Dose Variation in High Dose Radiation Brachytherapy

    Energy Technology Data Exchange (ETDEWEB)

    Hyvarinen, M; Leventouri, T; Casey, C; Long, S [Florida Atlantic University, Boca Raton, FL (United States); Pella, S [South Florida Radiation Oncology and Florida Atlantic University, Boca Raton, FL (United States); Dumitru, N [University of Bucharest, Bucharest-magurele, Ilfov (Romania); Herrera, R [Louis Stokes VA Medical Center, Cleveland, OH (United States)

    2014-06-15

    Purpose: The purpose of this study is to revise most of the HDR types of treatments with their applicators and their localization challenges. Since every millimeter of misplacement counts the study will look into the necessity of increasing the immobilization for several types of applicators Methods: The study took over 136 plans generated by the treatment planning system (TPS) looking into the applicator's placement in regard to the organs at risk (OR) and simulated the three possible displacements at the hottest dose point on the critical organ for several accessories to evaluate the variation of the delivered dose at the point due to the displacement. Results: Significant dose variation was obtained for the Contura, Savi, MLM and Prostate applicators. Conclusion: This study data indicates that an improvement of the immobilization devices for HDR is absolutely necessary. Better applicator fixation devices are required too. Developing new immobilization devices for all the applicators is recommended. Florida Atlantic University may provide Travel reimbursements.

  20. Color variations within glacial till, east-central North Dakota--A preliminary investigation

    Science.gov (United States)

    Kelly, T.E.; Baker, Claud H.

    1966-01-01

    Color variations (orange zones within buff-colored till) in drift in east-central North Dakota are believed to represent two tills of separate origin. Mean size, standard deviation, and number and type of pebbles show greater difference between the two tills than do skewness, kurtosis, and partial chemical analyses. Probably blocks of older till were moved by the last glacier crossing the area and were redeposited in a matrix of younger till.

  1. Origins of Tropospheric Ozone Interannual Variation (IAV) over Reunion: A Model Investigation

    Science.gov (United States)

    Liu, Junhua; Rodriguez, Jose M.; Thompson, Anne M.; Logan, Jennifer A.; Douglass, Anne R.; Olsen, Mark A.; Steenrod, Stephen D.; Posny, Francoise

    2016-01-01

    Observations from long-term ozonesonde measurements show robust variations and trends in the evolution of ozone in the middle and upper troposphere over Reunion Island (21.1 degrees South Latitude, 55.5 degrees East Longitude) in June-August. Here we examine possible causes of the observed ozone variation at Reunion Island using hindcast simulations by the stratosphere-troposphere Global Modeling Initiative chemical transport model for 1992-2014, driven by assimilated Modern-Era Retrospective Analysis for Research and Applications (MERRA) meteorological fields. Reunion Island is at the edge of the subtropical jet, a region of strong stratospheric-tropospheric exchange. Our analysis implies that the large interannual variation (IAV) of upper tropospheric ozone over Reunion is driven by the large IAV of the stratospheric influence. The IAV of the large-scale, quasi-horizontal wind patterns also contributes to the IAV of ozone in the upper troposphere. Comparison to a simulation with constant emissions indicates that increasing emissions do not lead to the maximum trend in the middle and upper troposphere over Reunion during austral winter implied by the sonde data. The effects of increasing emission over southern Africa are limited tothe lower troposphere near the surface in August-September.

  2. Transporte intra-hospitalar de pacientes internados em UTI Neonatal: fatores de risco para intercorrências Intra-hospital transport of neonatal intensive care patients: risk factors for complications

    Directory of Open Access Journals (Sweden)

    Anna Luiza P. Vieira

    2007-09-01

    Full Text Available OBJETIVO: Estudar os fatores associados à hipotermia e ao aumento da necessidade de oxigênio e/ou suporte ventilatório durante o transporte intra-hospitalar de pacientes internados em Unidade de Terapia Intensiva neonatal. MÉTODOS: Estudo prospectivo de todos os pacientes internados na unidade neonatal que necessitaram de transporte intra-hospitalar de janeiro de 1997 a dezembro de 2000, entre segundas-feiras e sextas-feiras, das 8h às 17h. Fatores associados à hipotermia e ao aumento da necessidade de oxigênio e/ou de suporte ventilatório durante e até duas horas após o transporte foram estudados por meio de regressão logística. RESULTADOS: Foram realizados 502 transportes no período. Os pacientes tinham em média 2.000g, 35 semanas de idade gestacional ao nascer e 22 dias de vida. As principais indicações do transporte foram: cirurgia e realização de exames de imagem. A hipotermia ocorreu em 17% dos transportes e o aumento da necessidade de oxigênio e/ou de suporte ventilatório em 7%. Fatores associados à hipotermia foram: duração do transporte >3h (OR=2,1; IC95%=1,2-3,6, presença de malformações neurológicas (OR=1,7; IC95%=1,1-2,5, transporte realizado em 1997 (OR=1,7; IC95%=1,1-2,6 e peso no transporte >3.500g (OR=0,3; IC95%=0,16-0,68. Fatores de risco para o aumento da necessidade de oxigênio e/ou de suporte ventilatório foram: idade gestacional ao nascimento em semanas (OR=0,9; IC95%=0,8-0,9, idade em dias no transporte (OR=1,0; IC95%=1,0-1,1 e presença de malformações gastrintestinais e geniturinárias (OR=3,1; IC95%=1,6-6,2. CONCLUSÕES: As intercorrências relativas ao transporte intra-hospitalar são freqüentes nos neonatos em UTI e estão associadas às condições dos pacientes e dos transportes.OBJECTIVE: Evaluate factors associated with hypothermia and increased need of oxygen and/or ventilatory support during intra-hospital transport of neonatal intensive care patients. METHODS: Prospective study of

  3. The use of high-throughput DNA sequencing in the investigation of antigenic variation: application to Neisseria species.

    Directory of Open Access Journals (Sweden)

    John K Davies

    Full Text Available Antigenic variation occurs in a broad range of species. This process resembles gene conversion in that variant DNA is unidirectionally transferred from partial gene copies (or silent loci into an expression locus. Previous studies of antigenic variation have involved the amplification and sequencing of individual genes from hundreds of colonies. Using the pilE gene from Neisseria gonorrhoeae we have demonstrated that it is possible to use PCR amplification, followed by high-throughput DNA sequencing and a novel assembly process, to detect individual antigenic variation events. The ability to detect these events was much greater than has previously been possible. In N. gonorrhoeae most silent loci contain multiple partial gene copies. Here we show that there is a bias towards using the copy at the 3' end of the silent loci (copy 1 as the donor sequence. The pilE gene of N. gonorrhoeae and some strains of Neisseria meningitidis encode class I pilin, but strains of N. meningitidis from clonal complexes 8 and 11 encode a class II pilin. We have confirmed that the class II pili of meningococcal strain FAM18 (clonal complex 11 are non-variable, and this is also true for the class II pili of strain NMB from clonal complex 8. In addition when a gene encoding class I pilin was moved into the meningococcal strain NMB background there was no evidence of antigenic variation. Finally we investigated several members of the opa gene family of N. gonorrhoeae, where it has been suggested that limited variation occurs. Variation was detected in the opaK gene that is located close to pilE, but not at the opaJ gene located elsewhere on the genome. The approach described here promises to dramatically improve studies of the extent and nature of antigenic variation systems in a variety of species.

  4. Preliminary investigation of foot pressure distribution variation in men and women adults while standing.

    Science.gov (United States)

    Periyasamy, R; Mishra, A; Anand, Sneh; Ammini, A C

    2011-09-01

    Women and men are anatomically and physiologically different in a number of ways. They differ in both shape and size. These differences could potentially mean foot pressure distribution variation in men and women. The purpose of this study was to analyze standing foot pressure image to obtain the foot pressure distribution parameter - power ratio variation between men and women using image processing in frequency domain. We examined 28 healthy adult subjects (14 men and 14 women) aged between 20 and 45 years was recruited for our study. Foot pressure distribution patterns while standing are obtained by using a PedoPowerGraph plantar pressure measurement system for foot image formation, a digital camera for image capturing, a TV tuner PC-add on card, a WinDvr software for still capture and Matlab software with dedicated image processing algorithms have been developed. Various PedoPowerGraphic parameters such as percentage medial impulse (PMI), fore foot to hind foot pressure distribution ratio (F/H), big toe to fore foot pressure distribution ratio (B/F) and power ratio (PR) were evaluated. In men, contact area was significantly larger in all regions of the foot compared with women. There were significant differences in plantar pressure distribution but there was no significant difference in F/H and B/F ratio. Mean PR value was significantly greater in men than women under the hind foot and fore foot. PMI value was greater in women than men. As compared to men, women have maximum PR variations in the mid foot. Hence there is significant difference at level pfeet can provide suitable guidelines to biomedical engineers and doctor for designing orthotic devices for reliving the area of excessively high pressure. Copyright © 2011 Elsevier Ltd. All rights reserved.

  5. Preliminay Investigation of Variation in Some Dark Adaptation Aspects fo Possible Relevance to Military Helicopter Aircrew.

    Science.gov (United States)

    1983-06-01

    Niven, J.I., McFarland, R.A., and Roughton, F.J. Variations in Visual Thresholds During Carbon Monoxide and Hypoxic Anoxia (abstract). Fed. Proc...and Niven, J.I. Visual Thresholds as an Index of the Modification of the Effects of Anoxia by Glucose. Am. J. Physiol. 144:378-88. 1945. 71... Diphosphoglycerate and Night Vision. Aviat. Space Environ. Med. 52(1):41-44. 1981. 100. Sexton, M., Malone, F. and Farnsworth, D. The Effect of Ultra- violet

  6. Investigation of variation of additional enthalpy of proteins with respect to pH by statistical mechanical methods

    International Nuclear Information System (INIS)

    Oylumoglu, G.

    2005-01-01

    In this study variation of additional enthalpy with respect to pH has been investigated by the statistical mechanical methods.. To bring up the additional effect, the partition function of the proteins are calculated by single protein molecule approximation. From the partition function, free energies of the proteins are obtained and by this way additional free energy has been used in the calculation of the terms in the thermodynamical quantity. Additional enthalpy H D has been obtained by taking effective electric field E and constant dipole moment M as thermodynamical variables and using Maxwell Equations. In the presented semi phenomenological theory, necessary data are taken from the experimental study of P.L. Privalov. The variation in the additional enthalpy H D has been investigated in the pH interval of 1-5 and the results of the calculations are discussed for Lysozyme

  7. Investigation of a connection of variations of atmospheric radiocarbon activity with some geophysical and astrophysical phenomena

    International Nuclear Information System (INIS)

    Kocharov, G.E.; Chernov, S.B.

    1980-01-01

    Relation of the radiocarbon concentration is dendrochronologically dated wood samples to solar activity, geomagnetic field variations and changes of global temperature near the earth surface for the last 500 years is studied. It is found that averaged 10-year Δ 14 C fluctuations of radiocarbon content in annual rings of trees experience noticeable variations with the 0.5% amplitude. To reveal the effect in the best way the Δ 14 C values averaged in the intervals equal to 11-year solar activity cycles and with a 4-year shift in relation to the latter, are obtained. It is shown that in the 1700-1805 period of time the Δ 14 C averaged values corresponding to peak values of the even 11-year solar activity cycles are mainly lower than the Δ 14 C averaged values corresponding to the odd cycle maximum values. In the 1835-1900 period the 14 C averaged values corresponding to the odd solar cycle maximum values are lesser than the Δ 14 C averaged values corresponding to the even cycle peaks [ru

  8. A comprehensive investigation into the effect of temperature variation on the mechanical properties of sustainable concrete

    Directory of Open Access Journals (Sweden)

    El Mir Abdulkader

    2017-01-01

    Full Text Available Minimizing the production energy and resources consumption are the key principle for engineering sustainability. In the case of concrete structures, this concept can be achieved by the use of materials in the most efficient way considering in the mix design the optimal mechanical and durability properties. The substitution of ordinary Portland cement for other supplementary cementitious materials is assessing the possibility of enhancing the sustainability and decreasing the environmental impact of concrete. Mass concrete is rich in cementitious materials which results in high temperature within the concrete, hence several hazards such as cracking or temperature differences between the interior and the surface of concrete could be prevented. An experimental study evaluated on several one cubic meter sized concrete elements in which during the primary phase of hydration, the temperature variation is recorded in several location offsets with respect to time. Thermal variations results are analyzed in accordance with the cement type, CO2 emission production of cement, compressive strength, water tightness, drying shrinkage and rapid chloride migration coefficient. The results indicate that slag cement CEM III/B 32.5, that incorporates highest amount of slag, ensured improved mechanical, thermal and durability properties in comparison with ordinary Portland cement CEM I 32.5.

  9. Microstructural investigation of variations in the proof strength of Nimonic PE16

    International Nuclear Information System (INIS)

    Riley, B.F.; Wilson, E.G.; Jones, A.R.

    1987-01-01

    Nimonic PE16 shows a correlation of stress rupture behaviour after irradiation with proof strength. Proof testing of material from bars from several casts yielded a relationship (Hall-Petch) between the peak-aged proof stress and grain size -1/2 but the scatter in proof stress values at a given grain size merited further microstructural study. Transmission electron microscopy revealed that high proof stress material contained dislocation densities consistent with material which had received 1 to 2% cold work, verified by examination of lightly prestrained tensile specimens. Ageing to peak strength induced partial recovery but some variability in proof stress remained. Variations in γ' size and composition having been eliminated, the scatter in proof stress values was attributed to variable cold work induced by the commercial bar straightening process. (Author)

  10. Microcosm investigations of stormwater pond sediment toxicity to embryonic and larval amphibians: Variation in sensitivity among species

    Energy Technology Data Exchange (ETDEWEB)

    Snodgrass, Joel W. [Department of Biological Sciences, Towson University, 8000 York Road, Towson, MD 21252 (United States)], E-mail: jsnodgrass@towson.edu; Casey, Ryan E. [Department of Chemistry, Towson University, 8000 York Road, Towson, MD 21252 (United States); Joseph, Debra; Simon, Judith A. [Department of Biological Sciences, Towson University, 8000 York Road, Towson, MD 21252 (United States)

    2008-07-15

    Stormwater ponds have become common features of modern development and often represent significant amounts of open space in urbanized areas. Although stormwater ponds may provide habitat for wildlife, factors responsible for producing variation in wildlife use of ponds have received limited attention. To investigate the role of variation in species tolerances of pollutants in structuring pond-breeding amphibian assemblages, we exposed species tolerant (Bufo americanus) and not tolerant (Rana sylvatica) of urbanization to pond sediments in laboratory microcosms. Pond microcosms had elevated sediment metal levels and chloride water concentrations. Among R. sylvatica embryos, exposure to pond sediments resulted in 100% mortality. In contrast, B. americanus embryos and larvae experienced only sublethal effects (i.e., reduced size at metamorphosis) due to pond sediment exposure. Our results suggest variation in pollutant tolerance among early developmental stages of amphibians may act in concert with terrestrial habitat availability to structure amphibian assemblages associated with stormwater ponds. - Variation among species in sensitivity to pollutants can influence stormwater pond amphibian assemblages.

  11. A Genre-Based Investigation of Discussion Sections of Research Articles in Dentistry and Disciplinary Variation

    Science.gov (United States)

    Basturkmen, Helen

    2012-01-01

    Outwardly the rhetorical organisation of sections of research reports in different disciplines can appear similar. Close examination, however, may reveal subtle differences. Numerous studies have drawn on the genre-based approach developed by Swales (1990, 2004) to investigate the schematic structure of sections of articles in a range of…

  12. Investigation of channel width-dependent threshold voltage variation in a-InGaZnO thin-film transistors

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Kuan-Hsien; Chou, Wu-Ching [Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan (China); Chang, Ting-Chang, E-mail: tcchang@mail.phys.nsysu.edu.tw [Department of Physics, National Sun Yat-Sen University, Kaohsiung 804, Taiwan (China); Advanced Optoelectronics Technology Center, National Cheng Kung University, Taiwan (China); Wu, Ming-Siou; Hung, Yi-Syuan; Sze, Simon M. [Department of Electronics Engineering, National Chiao Tung University, Hsinchu, Taiwan (China); Hung, Pei-Hua; Chu, Ann-Kuo [Department of Photonics, National Sun Yat-Sen University, Kaohsiung 804, Taiwan (China); Hsieh, Tien-Yu [Department of Physics, National Sun Yat-Sen University, Kaohsiung 804, Taiwan (China); Yeh, Bo-Liang [Advanced Display Technology Research Center, AU Optronics, No. 1, Li-Hsin Rd. 2, Hsinchu Science Park, Hsinchu 30078, Taiwan (China)

    2014-03-31

    This Letter investigates abnormal channel width-dependent threshold voltage variation in amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors. Unlike drain-induced source barrier lowering effect, threshold voltage increases with increasing drain voltage. Furthermore, the wider the channel, the larger the threshold voltage observed. Because of the surrounding oxide and other thermal insulating material and the low thermal conductivity of the IGZO layer, the self-heating effect will be pronounced in wider channel devices and those with a larger operating drain bias. To further clarify the physical mechanism, fast IV measurement is utilized to demonstrate the self-heating induced anomalous channel width-dependent threshold voltage variation.

  13. Investigation of the temporal evolution and spatial variation of in-cylinder engine fuel spray characteristics

    International Nuclear Information System (INIS)

    Qin, Wenjin; Hung, David L.S.; Xu, Min

    2015-01-01

    Highlights: • POD quadruple decomposition can reconstruct spray structure into different parts. • Different quadruple POD parts reveal different levels of spay field intensity. • Large scale structure part dominates the CCV of the entire spray. • In-cylinder flow field has the strongest effect on CCV of spray structure. - Abstract: The proper orthogonal decomposition (POD) method is applied to analyze the pulsing spray characteristics of the fuel injection inside a four-valve optical spark-ignition direct-injection (SIDI) engine. The instantaneous spray structures are decomposed into four parts, namely the mean structure, large scale structure, transition structure and small scale structure, respectively, by using POD quadruple decomposition. The cycle-to-cycle variations (CCV) of the in-cylinder pulsing spray structure are examined separately based on the four parts. Analysis results indicate that the four parts have different characteristics, and each individual part represents a specific instantaneous spray structure. First, the mean part contains more than 90% of the total intensity of the spray field throughout the whole injection process. Moreover, the large scale structure part has the highest CCV level among all four parts, and it dominates the CCV of the entire spray field. The CCV of spray can be influenced by different engine operating conditions. In particular, the in-cylinder flow field has the strongest effect on the spray CCV. The varying motion of the in-cylinder flow field significantly influences the CCV of the large scale spray part, which in turn affects the CCV characteristics of the whole spray field

  14. Mechanism investigation for poloxamer 188 raw material variation in cell culture.

    Science.gov (United States)

    Peng, Haofan; Ali, Amr; Lanan, Maureen; Hughes, Erik; Wiltberger, Kelly; Guan, Bing; Prajapati, Shashi; Hu, Weiwei

    2016-05-01

    Variability in poloxamer 188 (P188) raw material, which is routinely used in cell culture media to protect cells from hydrodynamic forces, plays an important role in the process performance. Even though tremendous efforts have been spent to understand the mechanism of poloxamer's protection, the root cause for lot-to-lot variation was not clear. A recent study reported that the low performance was not due to toxicity but inefficiency to protect cells (Peng et al., Biotechnol Prog. 2014;30:1411-1418). In this study, it was demonstrated for the first time that the addition of other surfactants even at a very low level can interfere with P188 resulting in a loss of efficiency. It was also found that the performance of P188 lots correlated well with its foam stability. Foam generated from low performing lots in baffled shaker flask lasts longer, which suggests that the components in the foam layers are different. The spiking of foam generated from a low performing lot into the media containing a high performance lot resulted in cell damage and low growth. Analytical studies using size exclusion chromatography (SEC) identified differences in high molecular weight (HMW) species present in the P188 lots. These differences are much clearer when comparing the HMW region of the SEC chromatogram of foam vs. bulk liquid samples. This study shows that low performing lots have enriched HMW species in foam samples due to high hydrophobicity, which can be potentially used as a screening assay. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:767-775, 2016. © 2016 American Institute of Chemical Engineers.

  15. Investigation of the phase morphology of bacterial PHA inclusion bodies by contrast variation SANS

    International Nuclear Information System (INIS)

    Russell, R.A.; Holden, P.J.; Garvey, C.J.; Wilde, K.L.; Hammerton, K.M.; Foster, L.J.

    2006-01-01

    Under growth-limiting conditions, many bacteria are able to metabolise excess organic acids into polyhydroxyalkanoates (PHA) and store these polymers as intracellular inclusions until the return of favourable conditions. Various models have been proposed for the macromolecular organisation of the boundary layer surrounding the polymer, and contrast-variation small-angle neutron scattering (SANS) was used to study its organisation. Inclusions formed by Pseudomonas oleovorans under hydrogenating conditions showed lowest scattering intensity at ca. 20% D 2 O. The inclusions consist of protein and membrane lipids in the boundary layer and polyhydroxyoctanoate (lipid) in the inclusion body. At 20% D 2 O the contributions of lipids were contrast matched with the solvent, indicating that lipids contributed the bulk of the scattering intensity observed at other D 2 O/H 2 O ratios. These results are inconsistent with a model of the boundary layer which proposed outer and inner layers of crystalline protein lattice sandwiching a membrane lipid membrane layer [E.S. Stuart, R.W. Lenz, R.C. Fuller, Can J Microbiol 41(Suppl 1) (1995) 84-93], and is more consistent with a model consisting of a lipid monolayer containing embedded proteins [U. Pieper-furst, M.H. Madkour, F. Mayer, A. Steinbuchel, J. Bacteriol. 176 (1994) 4328-4337.] By altering the H/D content of the precursors, we were able to collect SANS data from preparations of both deuterated and H/D copolymer inclusions, where initial PHA produced was hydrogenated followed by deuteration. Deuterated inclusions showed minimum intensity above 90% D 2 O/H 2 O whereas the sequentially produced copolymer (assumed to be in a core/shell arrangement) displayed minimum scattering some 20% lower, which is consistent with the increased hydrogenation of the boundary layer expected from its synthesis during supply of hydrogenated followed by deuterated precursors

  16. Investigation of switching frequency variations in self-oscillating class D amplifiers

    OpenAIRE

    Nielsen, Dennis; Knott, Arnold; Pfaffinger, Gerhard; Andersen, Michael A. E.

    2009-01-01

    Class D audio amplifiers have gained significant influence in sound reproduction due to their high efficiency. One of the most commonly used control methods in class D amplifiers is known as self-oscillation. An parameter of key interest in self-oscillating class D amplifiers is the switching frequency, which can be directly related to the performance of the amplifier. This paper will clearify the myth of the switching frequency through investigation of its dependency on modulation index and ...

  17. Significance of operator variation and the angle of illumination in lineament analysis on synoptic images. [LANDSAT geological investigations

    Science.gov (United States)

    Siegal, B. S.; Short, N. M.

    1977-01-01

    The significance of operator variation and the angle of illumination in acquired imagery is analyzed for lineament analysis. Five operators analyzed a LANDSAT image and four photographs of a plastic relief map illuminated at a low angle from varying directions of the Prescott, Arizona region. Significant differences were found in both number and length of the lineaments recognized by the different investigators for the images. The actual coincidence of lineaments recognized by the investigators for the same image is exceptionally low. Even the directional data on lineament orientation is significantly different from operator to operator and from image to image. Cluster analysis of the orientation data displays a clustering by operators rather than by images. It is recommended that extreme caution be taken before attempting to compare different investigators' results in lineament analysis.

  18. Investigating the impact of temporal and spatial variation in spring snow melt on summer soil respiration

    Science.gov (United States)

    John, G. P.; Papuga, S. A.; Wright, C. L.; Nelson, K.; Barron-Gafford, G. A.

    2010-12-01

    monsoon, late-melt sites were wetter than early-melt sites. These preliminary results are an important step toward understanding the role that temporal and spatial variations in snow cover, which will undoubtedly be impacted by climate change, play in the carbon dynamics of these semiarid mountain environments.

  19. Data from Investigating Variation in Replicability: A “Many Labs” Replication Project

    Directory of Open Access Journals (Sweden)

    Richard A. Klein

    2014-04-01

    Full Text Available This dataset is from the Many Labs Replication Project in which 13 effects were replicated across 36 samples and over 6,000 participants. Data from the replications are included, along with demographic variables about the participants and contextual information about the environment in which the replication was conducted. Data were collected in-lab and online through a standardized procedure administered via an online link. The dataset is stored on the Open Science Framework website. These data could be used to further investigate the results of the included 13 effects or to study replication and generalizability more broadly.

  20. Investigating the variations in survival rates for very preterm infants in ten European regions: the MOSAIC birth cohort

    DEFF Research Database (Denmark)

    Draper, Elizabeth S; Zeitlin, Jennifer; Fenton, Alan C

    2008-01-01

    OBJECTIVE: To investigate the variation in the survival rate and the mortality rates for very preterm infants across Europe. DESIGN: A prospective birth cohort of very preterm infants for ten geographically defined European regions during 2003 followed to discharge home from hospital. PARTICIPANTS......: All deliveries from 22+0 to 31+6 weeks gestation. MAIN OUTCOME MEASURE: All outcomes of pregnancy by gestational age group, including termination of pregnancy for congenital anomalies and other reasons, ante-partum stillbirth, intra-partum stillbirth, labour ward death, death after admission...

  1. Investigation of the effect of ionizing radiation on gene expression variation by the 'DNA chips': feasibility of a biological dosimeter

    International Nuclear Information System (INIS)

    Gruel, G.

    2005-01-01

    After having described the different biological effects of ionizing radiation and the different approaches to biological dosimetry, and introduced 'DNA chips' or DNA micro-arrays, the author reports the characterization of gene expression variations in the response of cells to a gamma irradiation. Both main aspects of the use DNA chips are investigated: fundamental research and diagnosis. This research thesis thus proposes an analysis of the effect of ionizing radiation using DNA chips, notably by comparing gene expression modifications measured in mouse irradiated lung, heart and kidney. It reports a feasibility study of bio-dosimeter based on expression profiles

  2. An investigation of natural genetic variation in the circadian system of Drosophila melanogaster: rhythm characteristics and methods of quantification.

    Science.gov (United States)

    Emery, P T; Morgan, E; Birley, A J

    1994-04-01

    Variation in four characteristics of the circadian locomotor activity rhythm was investigated in 24 true-breeding strains of Drosophila melanogaster with a view to establishing methods of phenotypic measurement sufficiently robust to allow subsequent biometric analysis. Between them, these strains formed a representative sample of the genetic variability of a natural population. Period, phase, definition (the degree to which a rhythmic signal was obscured by noise), and rhythm waveform were all found to vary continuously among the strains, although within each strain the rhythm phenotype was remarkably consistent. Each characteristic was found to be sufficiently robust to permit objective measurement using several different methods of quantification, which were then compared.

  3. Investigating the effects of climate variations on bacillary dysentery incidence in northeast China using ridge regression and hierarchical cluster analysis

    Directory of Open Access Journals (Sweden)

    Guo Junqiao

    2008-09-01

    Full Text Available Abstract Background The effects of climate variations on bacillary dysentery incidence have gained more recent concern. However, the multi-collinearity among meteorological factors affects the accuracy of correlation with bacillary dysentery incidence. Methods As a remedy, a modified method to combine ridge regression and hierarchical cluster analysis was proposed for investigating the effects of climate variations on bacillary dysentery incidence in northeast China. Results All weather indicators, temperatures, precipitation, evaporation and relative humidity have shown positive correlation with the monthly incidence of bacillary dysentery, while air pressure had a negative correlation with the incidence. Ridge regression and hierarchical cluster analysis showed that during 1987–1996, relative humidity, temperatures and air pressure affected the transmission of the bacillary dysentery. During this period, all meteorological factors were divided into three categories. Relative humidity and precipitation belonged to one class, temperature indexes and evaporation belonged to another class, and air pressure was the third class. Conclusion Meteorological factors have affected the transmission of bacillary dysentery in northeast China. Bacillary dysentery prevention and control would benefit from by giving more consideration to local climate variations.

  4. A retrospective study to investigate racial and ethnic variations in the treatment of psoriasis with etanercept.

    Science.gov (United States)

    Shah, Sejal K; Arthur, Angele; Yang, Yu-Ching; Stevens, Seth; Alexis, Andrew F

    2011-08-01

    Psoriasis is a chronic inflammatory condition that occurs worldwide; however, few studies have examined this condition in non-Caucasian populations. The purpose of this study was to investigate racial/ethnic differences in demographics, psoriasis severity, efficacy, safety, and health-related quality of life in patients treated with etanercept using data from the Etanercept Assessment of Safety and Effectiveness (EASE) in Psoriasis trial. This is an investigator-initiated evaluation of data from the EASE study. The study included 2511 patients (Caucasian n=2164; Hispanic/Latino n=173; African American n=98; Asian n=76). Although baseline Physicians' Global Assessment (PGA) scores were similar, we found significant baseline differences in patient characteristics, prior therapy, percentage of body surface area (%BSA) affected and Dermatology Life Quality Index (DLQI) scores between the groups. At baseline, the Caucasian group had the longest disease duration (19 years), but the lowest percentage of BSA involvement (28%). The Asian group had the highest percentage of BSA involvement (41%). Baseline DLQI score was lowest for Caucasians (12.0) and highest for Hispanic/Latinos (14.6). At week 12, response to therapy was similar in all ethnic/racial groups. The BSA involvement was reduced by more than 50 percent for all groups, but remained significantly higher for the Asian group (17%) than for the Caucasian (13%; P=0.0105) and African American groups (13%; P=0.0461). At week 12, the mean Asian DLQI score of 5.2 was significantly higher (worse) than scores for the Caucasian (3.5; P=0.0001) and Hispanic/Latino groups (3.8; P=0.028). For both percentage of BSA and DLQI, differences among racial/ethnic groups in the percentage improvement from baseline were not statistically significant. Adverse event rates were similar for the groups. Patient characteristics at enrollment differed among ethnic groups, but no significant racial/ethnic differences were found in safety or

  5. A quasi-experimental investigation of message appeal variations on organ donor registration rates.

    Science.gov (United States)

    Siegel, Jason T; Alvaro, Eusebio M; Crano, William D; Lac, Andrew; Ting, Sarah; Jones, Sara Pace

    2008-03-01

    Approximately 6,000 Americans die every year awaiting an organ transplant. Health promotion interventions may alleviate the shortage of viable organs by increasing the number of registered organ donors. This study is the first to evaluate the differential effectiveness of various organ donor messages in naturalistic settings. A 4 (Appeal)x4 (Exemplar)x4 (Location) counterbalanced quasi-experimental design was implemented. The behavioral outcome measure was the number of individuals who registered to be organ donors at computer kiosks. A number of significant main effects and interactions emerged. Most notably, of the 4 different appeals (counterargument, emotional, motivating action, dissonance), counterargument was by far the most efficacious, especially in academic-type settings (library, university, community college); the emotional appeal was most successful in hospitals. The findings from this study have implications for both organ donor investigations and health campaign research in general. Statistical interactions highlight the importance of evaluating multiple exemplars in multiple locations for each type of appeal when conducting health campaign research. Copyright (c) 2008 APA, all rights reserved.

  6. An investigation into CT radiation dose variations for head examinations on matched equipment

    International Nuclear Information System (INIS)

    Zarb, Francis; Foley, Shane; Toomey, Rachel; Rainford, Louise; Holm, Susanne; Evanoff, Michael G.

    2016-01-01

    This study investigated radiation dose and image quality differences for computed tomography (CT) head examinations across centres with matched CT equipment. Radiation dose records and imaging protocols currently employed across three European university teaching hospitals were collated, compared and coded as Centres A, B and C from specification matched CT equipment models. Patient scans (n = 40) obtained from Centres A and C were evaluated for image quality, based on the visualisation of Commission of European Community (CEC) image quality criteria using visual grading characteristic (VGC) analysis, where American Board of Radiology examiners (n = 11) stated their confidence in identifying anatomical criteria. Mean doses in terms of CT dose index (CTDI vol -mGy) and dose length product (DLP-mGy cm) were as follows: Centre A-33.12 mGy and 461.45 mGy cm; Centre B -101 mGy (base)/32 mGy (cerebrum) and 762 mGy cm and Centre C-71.98 mGy and 1047.26 mGy cm, showing a significant difference (p ≤ 0.05) in DLP across centres. VGC analysis indicated better visualisation of CEC criteria on Centre C images (VGC AUC 0.225). All three imaging protocols are routinely used clinically, and image quality is acceptable in each centre. Clinical centres with identical model CT scanners have variously customised their protocols achieving a range of dose savings and still resulting in clinically acceptable image quality. (authors)

  7. Investigation of GICs Associated with Large dB/dt Variations in Space

    Science.gov (United States)

    Dimitrakoudis, S.; Mann, I. R.; Murphy, K. R.; Rae, J.; Denton, M.; Milling, D. K.

    2016-12-01

    Geomagnetically induced currents (GICs) can be driven in terrestrial electrical power grids as a result of the induced electric fields arising from magnetic field changes driven in the coupled magnetosphere-ionosphere-ground system. Substorms are often hypothesised to be associated with the largest GIC effects on the ground, especially at higher latitudes. However, recent studies have suggested that other dayside phenomena such as sudden impulses and even ULF wave trains might also drive significant GICs. Using data from the CARISMA ground-based magnetometer network we examine the GIC response driven from a variety of magnetospheric processes. In particular we focus on events where large dB/dt is observed in-situ on GOES East and West satellites. Auroras, resulting from magnetospheric substorms, give us a dynamical view of sudden destabilizations in the nightside magnetosphere, of large spatial and temporal extent, that can drive large and potentially damaging geomagnetically induced currents (GICs) in terrestrial power grids. Since ground dB/dt can be used as a GIC proxy, we have surveyed GOES data since 2011 for the largest dB/dT events, and found some to be of the order of hundreds of nT in the span of a few seconds. These are observed in both the nightside and dayside, and, as such, we seek to establish connections to drivers affecting both sides of the terminator; tail activations and substorms on the nightside, large amplitude ULF waves, solar wind sudden impulses, and rapid changes in MIC current systems on the dayside. The short duration of these events, coupled with the use of conjugate satellite measurements and ground magnetometer arrays when possible, allows us to investigate their localization and the latitudinal extent of their effects and to further examine the potential role of non-substorm phenomena in generating GICs which may have adverse impacts in electrical power grids.

  8. Investigations into the Regional and Local Timescale Variations of Subglacial Drainage Networks

    Science.gov (United States)

    Hiester, Justin

    Subglacial water plays an important role in the regulation of an ice sheet's mass balance. It may be the dominant control on the velocities of ice streams and outlet glaciers on scales of months to millennia. Recent satellite observations of ice surface elevation changes have given researchers new insights into how subglacial water is stored and transported. Localized uplift and settling of the ice surface implies that lakes exist beneath the ice sheet that are being filled and drained on relatively short time scales. At the base of an ice sheet water can be transported through a variety of drainage networks or stored in subglacial lakes. Here, a numerical investigation of the mechanisms of transport and storage of subglacial water and the associated time scales is presented. Experiments are carried out using a finite element model of coupled ice and water flow. The first experiment seeks to understand the relationship between the depth of a basal depression and the area over which the feature affects basal water flow. It is found that as the perturbation to a topographic depression's depth is increased, water is rerouted in response to the perturbation. Additionally it is found that the relationship between perturbation depth and the extent upstream to which its effects reach is nonlinear. The second experiment examines how the aspect ratio of bed features (prolate, oblate, or equidimensional) influences basal water flow. It is found that the systems that develop and their interactions are mediated by both the topography and the feedbacks taken into account by the coupling of the systems in the model. Features oriented parallel to ice and water flow are associated with distributed fan systems that develop branches which migrate laterally across the domain and interact with one another on monthly and yearly timescales. Laterally oriented features develop laterally extensive ponds. As the ratio of longitudinal to lateral dimension of the topography is increased, a

  9. Structural Variation in Bacterial Glyoxalase I Enzymes: Investigation of the Metalloenzyme Glyoxalase I from Clostridium acetobutylicum

    Energy Technology Data Exchange (ETDEWEB)

    Suttisansanee U.; Swaminathan S.; Lau, K.; Lagishetty, S.; Rao, K. N.; Sauder, J. M.; Burley, S. K.; Honek, J. F.

    2011-11-04

    The glyoxalase system catalyzes the conversion of toxic, metabolically produced {alpha}-ketoaldehydes, such as methylglyoxal, into their corresponding nontoxic 2-hydroxycarboxylic acids, leading to detoxification of these cellular metabolites. Previous studies on the first enzyme in the glyoxalase system, glyoxalase I (GlxI), from yeast, protozoa, animals, humans, plants, and Gram-negative bacteria, have suggested two metal activation classes, Zn{sup 2+} and non-Zn{sup 2+} activation. Here, we report a biochemical and structural investigation of the GlxI from Clostridium acetobutylicum, which is the first GlxI enzyme from Gram-positive bacteria that has been fully characterized as to its three-dimensional structure and its detailed metal specificity. It is a Ni{sup 2+}/Co{sup 2+}-activated enzyme, in which the active site geometry forms an octahedral coordination with one metal atom, two water molecules, and four metal-binding ligands, although its inactive Zn{sup 2+}-bound form possesses a trigonal bipyramidal geometry with only one water molecule liganded to the metal center. This enzyme also possesses a unique dimeric molecular structure. Unlike other small homodimeric GlxI where two active sites are located at the dimeric interface, the C. acetobutylicum dimeric GlxI enzyme also forms two active sites but each within single subunits. Interestingly, even though this enzyme possesses a different dimeric structure from previously studied GlxI, its metal activation characteristics are consistent with properties of other GlxI. These findings indicate that metal activation profiles in this class of enzyme hold true across diverse quaternary structure arrangements.

  10. Use of restriction fragment length polymorphisms to investigate strain variation within Neisseria meningitidis

    Energy Technology Data Exchange (ETDEWEB)

    Williams, S.D.

    1989-01-01

    Similarity within bacterial populations is difficult to assess due to the limited number of characters available for evaluation and the heterogeneity of bacterial species. Currently, the preferred method used to evaluate the structure of bacterial populations is multilocus enzyme electrophoresis. However, this method is extremely cumbersome and only offers an indirect measure of genetic similarities. The development of a more direct and less cumbersome method for this purpose is warranted. Restriction fragment length polymorphism analysis was evaluated as a tool for use in the study of bacterial population structures and in the epidemiology and surveillance of infectious disease. A collection of Neisseria meningitidis was available for use in the investigation of this technique. Neisseria meningitidis is the causative agent of epidemic cerebrospinal meningitis and septicemia as well as a variety of other clinical manifestations. Each isolate in the collection was defined in terms of serogroup specificity, clinical history, geographic source, and date of isolation. Forty-six strains were chosen for this study. The DNA from each strain was restricted with Pst1 and EcoR1 and electrophoresed on agarose gels. The DNA was transferred to nylon filters and hybridized with P{sup 32} labeled DNA probes. Two randomly generated probes and a gene-specific probe were used to estimate the genetic similarities between and among the strains in the study population. A total of 28 different restriction fragment migration types were detected by the probes used. Data obtained from the RFLP analysis was analyzed by cluster analysis and multivariate statistical methods. A total of 7 clones groups were detected. Two of these appear to be major clones that comprise 35% of the population.

  11. Use of restriction fragment length polymorphisms to investigate strain variation within Neisseria meningitidis

    International Nuclear Information System (INIS)

    Williams, S.D.

    1989-01-01

    Similarity within bacterial populations is difficult to assess due to the limited number of characters available for evaluation and the heterogeneity of bacterial species. Currently, the preferred method used to evaluate the structure of bacterial populations is multilocus enzyme electrophoresis. However, this method is extremely cumbersome and only offers an indirect measure of genetic similarities. The development of a more direct and less cumbersome method for this purpose is warranted. Restriction fragment length polymorphism analysis was evaluated as a tool for use in the study of bacterial population structures and in the epidemiology and surveillance of infectious disease. A collection of Neisseria meningitidis was available for use in the investigation of this technique. Neisseria meningitidis is the causative agent of epidemic cerebrospinal meningitis and septicemia as well as a variety of other clinical manifestations. Each isolate in the collection was defined in terms of serogroup specificity, clinical history, geographic source, and date of isolation. Forty-six strains were chosen for this study. The DNA from each strain was restricted with Pst1 and EcoR1 and electrophoresed on agarose gels. The DNA was transferred to nylon filters and hybridized with P 32 labeled DNA probes. Two randomly generated probes and a gene-specific probe were used to estimate the genetic similarities between and among the strains in the study population. A total of 28 different restriction fragment migration types were detected by the probes used. Data obtained from the RFLP analysis was analyzed by cluster analysis and multivariate statistical methods. A total of 7 clones groups were detected. Two of these appear to be major clones that comprise 35% of the population

  12. Investigation of dielectric constant variations for Malaysians soil species towards its natural background dose

    Science.gov (United States)

    Jafery, Khawarizmi Mohd; Embong, Zaidi; Khee, Yee See; Haimi Dahlan, Samsul; Tajudin, Saiful Azhar Ahmad; Ahmad, Salawati; Kudnie Sahari, Siti; Maxwell, Omeje

    2018-01-01

    The correlation of natural background gamma radiation and real part of the complex relative permittivity (dielectric constant) for various species Malaysian soils was investigated in this research. The sampling sites were chosen randomly according to soils groups that consist of sedentary, alluvial and miscellaneous soil which covered the area of Batu Pahat, Kluang and Johor Bahru, Johor state of Malaysia. There are 11 types of Malaysian soil species that have been studied; namely Peat, Linau-Sedu, Selangor-Kangkong, Kranji, Telemong-Akob-Local Alluvium, Holyrood-Lunas, Batu Anam-Melaka-Tavy, Harimau Tampoi, Kulai-Yong Peng, Rengam-Jerangau, and Steepland soils. In-situ exposure rates of each soil species were measured by using portable gamma survey meter and ex-situ analysis of real part of relative permittivity was performed by using DAK (Dielectric Assessment Kit assist by network analyser). Results revealed that the highest and the lowest background dose rate were 94 ± 26.28 μR hr-1 and 7 ± 0.67 μR hr-1 contributed by Rengam Jerangau and Peat soil species respectively. Meanwhile, dielectric constant measurement, it was performed in the range of frequency between 100 MHz to 3 GHz. The measurements of each soils species dielectric constant are in the range of 1 to 3. At the lower frequencies in the range of 100 MHz to 600 MHz, it was observed that the dielectric constant for each soil species fluctuated and inconsistent. But it remained consistent in plateau form of signal at higher frequency at range above 600 MHz. From the comparison of dielectric properties of each soil at above 600 MHz of frequency, it was found that Rengam-Jerangau soil species give the highest reading and followed by Selangor-Kangkong species. The average dielectric measurement for both Selangor-Kangkong and Rengam-Jerangau soil species are 2.34 and 2.35 respectively. Meanwhile, peat soil species exhibits the lowest dielectric measurement of 1.83. It can be clearly seen that the pattern

  13. An Investigation of Amphitheater-Headed Canyon Distribution, Morphology Variation, and Longitudinal Profile Controls in Escalante and Tarantula Mesa, Utah.

    Science.gov (United States)

    Ryan, A. J.; Whipple, K. X.

    2014-12-01

    Amphitheater-headed canyons are primarily distinguished from typical fluvial channels by their abrupt headwall terminations. A key goal in the study of river canyons is to establish a reliable link between form and formation processes. This is of particular significance for Mars, where, if such links can be established, amphitheater-headed canyons could be used to determine ancient erosion mechanisms and, by inference, climate conditions. Type examples in arid regions on Earth, such as in Escalante River, Utah, previously have been interpreted as products of groundwater seepage erosion. We investigate amphitheater-headed canyons in Escalante and Tarantula Mesa where variations in canyon head morphology may hold clues for the relative roles of rock properties and fluvial and groundwater processes. In lower Escalante, amphitheaters are only present where canyons have breached the Navajo Sandstone - Kayenta Formation contact. In some canyons, amphitheater development appears to have been inhibited by an abundance of coarse bedload. In Tarantula Mesa, canyons have a variety of headwalls, from amphitheaters to stepped knickzones. Headwall morphology distribution is directly related to the spatially variable presence of knickpoint-forming, fine-grained interbeds within cliff-forming sandstones. Amphitheaters only form where the sandstone unit is undisrupted by these interbeds. Finally, most canyons in Escalante and Tarantula Mesa, regardless of substrate lithology, amphitheater presence, or groundwater spring intensity, are well described by a slope-area power law relationship with regionally constant concavity and normalized steepness indices. This suggests that all channels here are subject to the same erosion rates, independent of groundwater weathering intensity. Thus: 1) variations in canyon headwall form do not necessary relate to differences in fluvial history, 2) stratigraphic variations are clearly of importance in sedimentary canyon systems, and 3) although

  14. Computerized system to measure interproximal alveolar bone levels in epidemiologic, radiographic investigations. II. Intra- and inter-examinar variation study

    Energy Technology Data Exchange (ETDEWEB)

    Wouters, F.R.; Frithiof, L.; Soeder, P.Oe.; Hellden, L.; Lavstedt, S.; Salonen, L.

    1988-01-01

    The study was aimed at analyzing intra- and inter-examiner variations in computerized measurement and in non-measurability of alveolar bone level in a cross-sectional, epidemiologic material. At each interproximal tooth surface, alveolar bone height in percentage of root length (B/R) and tooth length (B/T) were determined twice by one examiner and once by a second examiner from X5-magnified periapical radiographs. The overall intra- and inter-examiner variations in measurement were 2.85% and 3.84% of root length and 1.97% and 2.82% of tooth length, respectively. The varations were different for different tooth groups and for different degrees of severity of marginal periodontitis. The overall proportions on non-measurable tooth surfaces varied with examiner from 32% to 39% and from 43% to 48% of the available interproximal tooth surfaces for B/R and B/T, respectively. With regard to the level of reliability, the computerized method reported is appropriate to cross-sectional, epidemiologic investigations from radiographs.

  15. Investigating the variations in survival rates for very preterm infants in ten European regions: the MOSAIC birth cohort

    DEFF Research Database (Denmark)

    Draper, Elizabeth S; Zeitlin, Jennifer; Fenton, Alan C

    2008-01-01

    OBJECTIVE: To investigate the variation in the survival rate and the mortality rates for very preterm infants across Europe. DESIGN: A prospective birth cohort of very preterm infants for ten geographically defined European regions during 2003 followed to discharge home from hospital. PARTICIPANTS...... to directly compare international statistics for mortality in very preterm infants, data collection needs to be standardised. We believe that the standard point of comparison should be using all those infants alive at the onset of labour as the denominator for comparisons of mortality rates for very preterm...... for NIC. For babies rates to discharge from NIC for very preterm deliveries and in the timing of death across the MOSAIC regions. In order...

  16. The investigation of spatiotemporal variations of land surface temperature based on land use changes using NDVI in southwest of Iran

    Science.gov (United States)

    Fathizad, Hassan; Tazeh, Mahdi; Kalantari, Saeideh; Shojaei, Saeed

    2017-10-01

    Land use changes can bring about changes in land surface temperature (LST) which is influenced by climatic conditions and physical characteristics of the land surface. In this study, spatiotemporal variations of land surface temperature have been investigated in the desert area of Dasht-e-Abbas, Ilam, based on a variety of land use changes. The investigated periods for the study include 1990, 2000 and 2010 using Landsat image data. First, in mapping land use we used the Fuzzy ARTMAP Neural Network Classification method followed by determination of the NDVI Index to estimate land surface temperature. The results show an increase in LST in areas where degradation, land use and land cover changes have occurred. In 1990, 2000 and 2010, the average land surface temperature of the Fair Rangelands was 26.72 °C, 30.06 °C and 30.95 °C, respectively. This rangeland has been reduced by about 5%. For poor rangelands, the average LSTs were 26.95, 32.83 and 34.49 Cº, respectively which had a 18% reduction. In 1990, 2000 and 2010, the average land surface temperatures of agricultural lands were 24.31 °C, 27.87 °C and 28.61 °C, respectively which has been an increasing trend. The reason can be attributed to changes in cropping patterns of the study area.

  17. Triarchic Psychopathy Dimensions in Chimpanzees (Pan troglodytes: Investigating Associations with Genetic Variation in the Vasopressin Receptor 1A Gene

    Directory of Open Access Journals (Sweden)

    Robert D. Latzman

    2017-07-01

    Full Text Available Vasopressin is a neuropeptide known to be associated with the development and evolution of complex socio-emotional behaviors including those relevant to psychopathic personality. In both humans and chimpanzees, recent research suggests a strong genetic contribution to individual variation in psychopathic traits. To date, however, little is known concerning specific genes that might explain the observed heritability of psychopathy. In a relatively large sample of captive chimpanzees (N = 164, the current study thus sought to investigate gene-environment associations between triarchic psychopathy dimensions (i.e., disinhibition, meanness, and boldness and (1 early social rearing experiences and (2 polymorphisms in the promoter region of the V1A receptor gene (AVPR1A. Among chimpanzees raised by their biological conspecific mothers, AVPR1A was found to uniquely explain variability in disinhibition and in sex-specific ways for boldness and a total psychopathy score; however, in contrast, no significant associations were found between AVPR1A and any of the triarchic psychopathy dimensions in chimpanzees raised the first 3 years of life in a human nursery. Thus, when considered in its entirety, results suggest an important contributory influence of V1A receptor genotype variation in the explanation of the development of psychopathy under some but not all early rearing conditions. Results of the current study provide additional support for the assertion that psychopathic tendencies are rooted in basic, evolutionarily-meaningful dispositions, and provide support for a primate-translational operationalization of key neurobehavioral constructs relevant both to psychopathy and to broader forms of psychopathology.

  18. Child Maltreatment, Inflammation, and Internalizing Symptoms: Investigating the Roles of C-Reactive Protein, Gene Variation and Neuroendocrine Regulation

    Science.gov (United States)

    Cicchetti, Dante; Handley, Elizabeth D.; Rogosch, Fred A.

    2015-01-01

    Prior research has found inconsistent evidence regarding the association among childhood adversity, inflammation, and internalizing symptoms, perhaps because previous studies have yet to adequately integrate important factors such as the timing of the adversity, genetic variation, and other relevant processes such as neuroendocrine regulation. The aims of the present study were threefold: 1) Determine whether the effect of the timing of child maltreatment on C-reactive protein (CRP), an inflammatory marker, varies by CRP gene variation; 2) Explore whether links between salivary CRP and childhood internalizing symptoms depend on the presence and timing of maltreatment experiences; 3) Investigate the role of CRP in the relations between child neuroendocrine regulation and internalizing symptoms and examine whether these associations are moderated by the presence and timing of child maltreatment. Participants included a sample of 267 maltreated and 222 nonmaltreated children (M age= 9.72, SD=0.99; 52.4% male; 66% African-American) who attended a summer day camp research program designed for school-aged low-income children. Department of Human Services records were examined to determine the onset and recency of maltreatment for children in the maltreated group. Results indicated that among children with recent onset maltreatment, those with at least one A allele from CRP SNP rs1417938 evidenced significantly higher CRP levels compared to recently maltreated children carrying the TT genotype. Moreover, higher levels of CRP were associated with higher levels of internalizing symptoms only for recently maltreated children. Finally, we did not find support for salivary CRP as a mechanism in the relation between neuroendocrine regulation and childhood internalizing symptoms. Our findings highlight the importance of the timing of child maltreatment and have important implications for characterizing variability in inflammation and internalizing symptoms among youth. PMID

  19. Investigating the potential role of genetic and epigenetic variation of DNA methyltransferase genes in hyperplastic polyposis syndrome.

    Directory of Open Access Journals (Sweden)

    Musa Drini

    2011-02-01

    Full Text Available Hyperplastic Polyposis Syndrome (HPS is a condition associated with multiple serrated polyps, and an increased risk of colorectal cancer (CRC. At least half of CRCs arising in HPS show a CpG island methylator phenotype (CIMP, potentially linked to aberrant DNA methyltransferase (DNMT activity. CIMP is associated with methylation of tumor suppressor genes including regulators of DNA mismatch repair (such as MLH1, MGMT, and negative regulators of Wnt signaling (such as WIF1. In this study, we investigated the potential for interaction of genetic and epigenetic variation in DNMT genes, in the aetiology of HPS.We utilized high resolution melting (HRM analysis to screen 45 cases with HPS for novel sequence variants in DNMT1, DNMT3A, DNMT3B, and DNMT3L. 21 polyps from 13 patients were screened for BRAF and KRAS mutations, with assessment of promoter methylation in the DNMT1, DNMT3A, DNMT3B, DNMT3L MLH1, MGMT, and WIF1 gene promoters.No pathologic germline mutations were observed in any DNA-methyltransferase gene. However, the T allele of rs62106244 (intron 10 of DNMT1 gene was over-represented in cases with HPS (p<0.01 compared with population controls. The DNMT1, DNMT3A and DNMT3B promoters were unmethylated in all instances. Interestingly, the DNMT3L promoter showed low levels of methylation in polyps and normal colonic mucosa relative to matched disease free cells with methylation level negatively correlated to expression level in normal colonic tissue. DNMT3L promoter hypomethylation was more often found in polyps harbouring KRAS mutations (p = 0.0053. BRAF mutations were common (11 out of 21 polyps, whilst KRAS mutations were identified in 4 of 21 polyps.Genetic or epigenetic alterations in DNMT genes do not appear to be associated with HPS, but further investigation of genetic variation at rs62106244 is justified given the high frequency of the minor allele in this case series.

  20. Investigating the Variation of Volatile Compound Composition in Maotai-Flavoured Liquor During Its Multiple Fermentation Steps Using Statistical Methods

    Directory of Open Access Journals (Sweden)

    Zheng-Yun Wu

    2016-01-01

    Full Text Available The use of multiple fermentations is one of the most specific characteristics of Maotai-flavoured liquor production. In this research, the variation of volatile composition of Maotai-flavoured liquor during its multiple fermentations is investigated using statistical approaches. Cluster analysis shows that the obtained samples are grouped mainly according to the fermentation steps rather than the distillery they originate from, and the samples from the first two fermentation steps show the greatest difference, suggesting that multiple fermentation and distillation steps result in the end in similar volatile composition of the liquor. Back-propagation neural network (BNN models were developed that satisfactorily predict the number of fermentation steps and the organoleptic evaluation scores of liquor samples from their volatile compositions. Mean impact value (MIV analysis shows that ethyl lactate, furfural and some high-boiling-point acids play important roles, while pyrazine contributes much less to the improvement of the flavour and taste of Maotai-flavoured liquor during its production. This study contributes to further understanding of the mechanisms of Maotai-flavoured liquor production.

  1. The first photometric investigation and orbital period variation analysis of the W UMa type binary IK Bootis

    Science.gov (United States)

    Kriwattanawong, Wichean; Sanguansak, Nuanwan; Maungkorn, Sakdawoot

    2017-08-01

    With new CCD observations of the W UMa type binary IK Boo, we present the first investigation of photometric parameters and orbital period change. The BVRc light curve fit shows that IK Boo is a W-type contact system with a mass ratio of q = 1.146 and a shallow contact with a fill-out factor of f = 2.22%. The orbital period decrease was found to be a rate of -3.28 × 10-7 d yr-1, corresponding to a mass transfer from the more massive to the less massive component with a rate of -2.83 × 10-6 M⊙ yr-1. The inner and outer critical Roche lobes will contract and cause the contact degree to increase. Therefore, IK Boo may evolve into a deeper contact system. Furthermore, a possible cyclic variation was found with a period of 9.74 yr, which could be explained by the light-travel time effect due to the existence of a third companion in the system.

  2. Investigating the origins of nanostructural variations in differential ethnic hair types using X-ray scattering techniques.

    Science.gov (United States)

    Wade, M; Tucker, I; Cunningham, P; Skinner, R; Bell, F; Lyons, T; Patten, K; Gonzalez, L; Wess, T

    2013-10-01

    Human hair is a major determinant of visual ethnic differentiation. Although hair types are celebrated as part of our ethnic diversity, the approach to hair care has made the assumption that hair types are structurally and chemically similar. Although this is clearly not the case at the macroscopic level, the intervention of many hair treatments is at the nanoscopic and molecular levels. The purpose of the work presented here is to identify the main nanoscopic and molecular hierarchical differences across five different ethnic hair types from hair fibres taken exclusively from the scalp. These are Afro (subdivided into elastic 'rubber' and softer non-elastic 'soft'), Chinese, European and Mullato (mixed race). Small angle X-Ray scattering (SAXS) is a technique capable of resolving nanostructural variations in complex materials. Individual hair fibres from different ethnic hair types were used to investigate structural features found in common and also specific to each type. Simultaneous wide angle X-Ray scattering (WAXS) was used to analyse the submolecular level structure of the fibrous keratin present. The data sets from both techniques were analysed with principal component analysis (PCA) to identify underlying variables. Principal component analysis of both SAXS and WAXS data was shown to discriminate the scattering signal between different hair types. The X-ray scattering results show a common underlying keratin intermediate filament (KIF) structure. However, distinct differences were observed in the preferential orientation and intensity signal from the lipid component of the hair. In addition, differences were observed in the intensity distribution of the very low-angle sample-dependent diffuse scatter surrounding the 'beamstop.' The results indicate that the fibrous keratin scaffold remains consistent between ethnic hair types. The hierarchies made by these may be modulated by variation in the content of keratin-associated proteins (KAPs) and lipids that

  3. Investigation of spatial and historical variations of air pollution around an industrial region using trace and macro elements in tree components

    Energy Technology Data Exchange (ETDEWEB)

    Odabasi, Mustafa, E-mail: mustafa.odabasi@deu.edu.tr [Department of Environmental Engineering, Faculty of Engineering, Dokuz Eylul University, Tinaztepe Campus, 35160 Buca, Izmir (Turkey); Tolunay, Doganay [Department of Forestry Engineering, Faculty of Forestry, Istanbul University, 34470 Sariyer, Istanbul (Turkey); Kara, Melik; Ozgunerge Falay, Ezgi; Tuna, Gizem; Altiok, Hasan; Dumanoglu, Yetkin; Bayram, Abdurrahman; Elbir, Tolga [Department of Environmental Engineering, Faculty of Engineering, Dokuz Eylul University, Tinaztepe Campus, 35160 Buca, Izmir (Turkey)

    2016-04-15

    Several trace and macro elements (n = 48) were measured in pine needle, branch, bark, tree ring, litter, and soil samples collected at 27 sites (21 industrial, 6 background) to investigate their spatial and historical variation in Aliaga industrial region in Turkey. Concentrations generally decreased with distance from the sources and the lowest ones were measured at background sites far from major sources. Spatial distribution of anthropogenic trace elements indicated that their major sources in the region are the iron-steel plants, ship-breaking activities and the petroleum refinery. Patterns of 40 elements that were detected in most of the samples were also evaluated to assess their suitability for investigation of historical variations. Observed increasing trends of several trace and macro elements (As, Cr, Fe, Mo, Ni, V, Cu, Pb, Sb, Sn, and Hg) in the tree-ring samples were representative for the variations in anthropogenic emissions and resulting atmospheric concentrations in Aliaga region. It was shown that lanthanides (La, Ce, Pr, Nd, Sm, Gd, Dy, Er, Yb) could also be used for the investigation of historical variations due to specific industrial emissions (i.e., petroleum refining). Results of the present study showed that tree components, litter, and soil could be used to determine the spatial variations of atmospheric pollution in a region while tree rings could be used to assess the historical variations. - Highlights: • Iron-steel plants and refinery are the major trace element emitters in Aliaga region. • Tree components, litter and soil reflected the spatial variations of trace elements. • Elements in tree rings represented the historical variations in air pollution.

  4. Investigating ethnic variations in reporting of psychotic symptoms: a multiple-group confirmatory factor analysis of the Psychosis Screening Questionnaire.

    Science.gov (United States)

    Heuvelman, Hein; Nazroo, James; Rai, Dheeraj

    2018-03-12

    Epidemiological evidence suggests risk for psychosis varies with ethnicity in Western countries. However, there is little evidence to date on the cross-cultural validity of screening instruments used for such comparisons. Combining two existing UK population-based cohorts, we examined risk for reporting psychotic symptoms across White British (n = 3467), White Irish (n = 851), Caribbean (n = 1899), Indian (n = 2590), Pakistani (n = 1956) and Bangladeshi groups (n = 1248). We assessed the psychometric properties of the Psychosis Screening Questionnaire (PSQ) with a multiple-group confirmatory factor analysis, assessing the equivalence of factor loadings, response thresholds and residual variances in an analysis of measurement non-invariance. Compared with prevalence among British Whites (5.4%), the prevalence of self-reported psychotic symptoms was greater in the Caribbean group (12.7%, adjusted OR = 2.38 [95% CI 1.84-3.07]). Prevalence was also increased among Pakistani individuals (8.3%, adjusted OR = 1.36 [1.01-1.84]) although this difference was driven by a greater likelihood of reporting paranoid symptoms. PSQ items for thought interference, strange experience and hallucination were measured in equivalent ways across ethnic groups. However, our measurement models suggested that paranoid symptoms were measured less reliably among ethnic minorities than among British Whites and appeared to exaggerate latent differences between Pakistani and White British groups when measurement non-invariance was not accounted for. Notwithstanding evidence for measurement non-invariance, the greater risk for reporting psychotic symptoms among Caribbean individuals is unlikely to be an artefact of measurement. Greater residual variance in the recording of paranoid symptoms among ethnic minority respondents warrants caution in using this item to investigate ethnic variation in psychosis risk.

  5. Investigation of reactivity variations of the Isfahan MNSR reactor due to variations in the thickness of the core top beryllium layer using WIMSD and MCNP codes

    Directory of Open Access Journals (Sweden)

    A Shirani

    2010-12-01

    Full Text Available In this work, the Isfahan Miniature Neutron Source Reactor (MNSR is first simulated using the WIMSD code, and its fuel burn-up after 7 years of operation ( when the reactor was revived by adding a 1.5 mm thick beryllium shim plate to the top of its core and also after 14 years of operation (total operation time of the reactor is calculated. The reactor is then simulated using the MCNP code, and its reactivity variation due to adding a 1.5 mm thick beryllium shim plate to the top of the reactor core, after 7 years of operation, is calculated. The results show good agreement with the available data collected at the revival time. Exess reactivity of the reactor at present time (after 14 years of operation and after 7 years of the the reactor revival time is also determined both experimentally and by calculation, which show good agreement, and indicate that at the present time there is no need to add any further beryllium shim plate to the top of the reactor core. Furthermore, by adding more beryllium layers with various thicknesses to the top of the reactor core, in the input program of the MCNP program, reactivity value of these layers is calculated. From these results, one can predict the necessary beryllium thickness needed to reach a desired reactivity in the MNSR reactor.

  6. Investigation of genetic variation in scavenger receptor class B, member 1 (SCARB1) and association with serum carotenoids

    Science.gov (United States)

    McKay, Gareth J; Loane, Edward; Nolan, John M; Patterson, Christopher C; Meyers, Kristin J; Mares, Julie A; Yonova-Doing, Ekaterina; Hammond, Christopher J; Beatty, Stephen; Silvestri, Giuliana

    2013-01-01

    Objective To investigate association of scavenger receptor class B, member 1 (SCARB1) genetic variants with serum carotenoid levels of lutein (L) and zeaxanthin (Z) and macular pigment optical density (MPOD). Design A cross-sectional study of healthy adults aged 20-70. Participants 302 participants recruited following local advertisement. Methods MPOD was measured by customized heterochromatic flicker photometry. Fasting blood samples were taken for serum L and Z measurement by HPLC and lipoprotein analysis by spectrophotometric assay. Forty-seven single nucleotide polymorphisms (SNPs) across SCARB1 were genotyped using Sequenom technology. Association analyses were performed using PLINK to compare allele and haplotype means, with adjustment for potential confounding and correction for multiple comparisons by permutation testing. Replication analysis was performed in the TwinsUK and CAREDS cohorts. Main outcome measures Odds ratios (ORs) for macular pigment optical density area, serum lutein and zeaxanthin concentrations associated with genetic variations in SCARB1 and interactions between SCARB1 and sex. Results Following multiple regression analysis with adjustment for age, body mass index, sex, high-density lipoprotein cholesterol (HDLc), low-density lipoprotein cholesterol (LDLc), triglycerides, smoking, dietary L and Z levels, 5 SNPs were significantly associated with serum L concentration and 1 SNP with MPOD (P<0.01). Only the association between rs11057841 and serum L withstood correction for multiple comparisons by permutation testing (P<0.01) and replicated in the TwinsUK cohort (P=0.014). Independent replication was also observed in the CAREDS cohort with rs10846744 (P=2×10−4), a SNP in high linkage disequilibrium with rs11057841 (r2=0.93). No significant interactions by sex were found. Haplotype analysis revealed no stronger association than obtained with single SNP analyses. Conclusions Our study has identified association between rs11057841 and

  7. Investigation of the seasonal variations of aerosol physicochemical properties and their impact on cloud condensation nuclei number concentration

    Science.gov (United States)

    Logan, Timothy S.

    Aerosols are among the most complex yet widely studied components of the atmosphere not only due to the seasonal variability of their physical and chemical properties but also their effects on climate change. The three main aerosol types that are known to affect the physics and chemistry of the atmosphere are: mineral dust, anthropogenic pollution, and biomass burning aerosols. In order to understand how these aerosols affect the atmosphere, this dissertation addresses the following three scientific questions through a combination of surface and satellite observations: SQ1: What are the seasonal and regional variations of aerosol physico-chemical properties at four selected Asian sites? SQ2: How do these aerosol properties change during transpacific and intra-continental long range transport? SQ3: What are the impacts of aerosol properties on marine boundary layer cloud condensation nuclei number concentration? This dissertation uses an innovative approach to classify aerosol properties by region and season to address SQ1. This is useful because this method provides an additional dimension when investigating the physico-chemical properties of aerosols by linking a regional and seasonal dependence to both the aerosol direct and indirect effects. This method involves isolating the aerosol physico-chemical properties into four separate regions using AERONET retrieved Angstrom exponent (AEAOD) and single scattering co-albedo (o oabs) to denote aerosol size and absorptive properties. The aerosols events are then clustered by season. The method is first applied to four AERONET sites representing single mode aerosol dominant regions: weakly absorbing pollution (NASA Goddard), strongly absorbing pollution (Mexico City), mineral dust (Solar Village), and biomass burning smoke (Alta Floresta). The method is then applied to four Asian sites that represent complicated aerosol components. There are strong regional and seasonal influences of the four aerosol types over the

  8. Investigation of Interfraction Variations of MammoSite Balloon Applicator in High-Dose-Rate Brachytherapy of Partial Breast Irradiation

    International Nuclear Information System (INIS)

    Kim, Yongbok; Johnson, Mark M.S.; Trombetta, Mark G.; Parda, David S.; Miften, Moyed

    2008-01-01

    Purpose: To measure the interfraction changes of the MammoSite applicator and evaluate their dosimetric effect on target coverage and sparing of organs at risk. Methods and Materials: A retrospective evaluation of the data from 19 patients who received 10 fractions (34 Gy) of high-dose-rate partial breast irradiation was performed. A computed tomography-based treatment plan was generated for Fraction 1, and a computed tomography scan was acquired just before the delivery of each fraction to ensure a consistent shape of the balloon. The eccentricity, asymmetry, and planning target volume (PTV) for plan evaluation purposes (PTV E VAL), as well as trapped air gaps, were measured for all patients. Furthermore, 169 computed tomography-based treatment plans were retrospectively generated for Fractions 2-10. Interfraction dosimetric variations were evaluated using the %PTV E VAL coverage, target dose homogeneity index, target dose conformal index, and maximum doses to the organs at risks. Results: The average variation of eccentricity and asymmetry from Fraction 1 values of 3.5% and 1.1 mm was -0.4% ± 1.6% and -0.1 ± 0.6 mm. The average trapped air gap volume was dramatically reduced from before treatment (3.7 cm 3 ) to Fraction 1 (0.8 cm 3 ). The PTV E VAL volume change was insignificant. The average variation for the %PTV E VAL, target dose homogeneity, and target dose conformal index from Fraction 1 values of 94.7%, 0.64, and 0.85 was 0.15% ± 2.4%, -0.35 ± 2.4%, and -0.34 ± 4.9%, respectively. The average Fraction 1 maximum skin and ipsilateral lung dose of 3.2 Gy and 2.0 Gy varied by 0.08 ± 0.47 and -0.16 ± 0.29 Gy, respectively. Conclusion: The interfraction variations were patient specific and fraction dependent. Although the average interfraction dose variations for the target and organs at risk were not clinically significant, the maximum variations could be clinically significant

  9. Mangrove forests submitted to depositional processes and salinity variation investigated using satellite images and vegetation structure surveys

    OpenAIRE

    Cunha-Lignon, M.; Kampel, M.; Menghini, R.P.; Schaeffer-Novelli, Y.; Cintrón, G.; Dahdouh-Guebas, F.

    2011-01-01

    The current paper examines the growth and spatio-temporal variation of mangrove forests in response to depositional processes and different salinity conditions. Data from mangrove vegetation structure collected at permanent plots and satellite images were used. In the northern sector important environmental changes occurred due to an artificial channel producing modifications in salinity. The southern sector is considered the best conserved mangrove area along the coast of São Paulo State, Br...

  10. An experimental investigation on bending stiffness and neutral axis depth variation of over-reinforced high strength concrete beams

    International Nuclear Information System (INIS)

    Mohammadhassani, Mohammad; Bin Jumaat, Mohd Zamin; Chemrouk, Mohamed; Akbar Maghsoudi, Ali; Jameel, Mohammed; Akib, Shatirah

    2011-01-01

    Highlights: → Improvement of the assessment of correspond stress for calculation of modules of elasticity → better evaluation of cracked moment of inertia. → Low distinction of neutral axis depth → low bending stiffness variation. → Rate of slope in the line connecting the origin of first crack to yield point of N.A.D-LOAD graph → rate of ductility of beam section. - Abstract: The present work is an attempt to study the neutral axis variation and the evolution of the moment inertia with the loading of over reinforced high strength concrete sections in conjunction with ACI 318-05. In this sense, four high strength concrete beams, having different tension reinforcement quantities expressed as proportions of the balanced steel ratio (0.75ρ b , 0.85ρ b , ρ b , 1.2ρ b ) were tested. Measurements of the deflection and the reinforcement and concrete strains of all specimens were made during the loading process. The load-neutral axis depth variation and the load-section stiffness curves were drawn. The slope of the line connecting the origin of the first crack to the initial yielding of the failure point in the neutral axis depth-load graphs shows the rate of ductility; ductile behaviour in the beam increases as the slope becomes steeper. Based on the results of this study, it is recommended that the modulus of elasticity of concrete E c be reviewed and evaluated at a stress higher than 0.5f ' c for the determination of the cracked moment of inertia.

  11. Analytical Investigation of Beam Deformation Equation using Perturbation, Homotopy Perturbation, Variational Iteration and Optimal Homotopy Asymptotic Methods

    DEFF Research Database (Denmark)

    Farrokhzad, F.; Mowlaee, P.; Barari, Amin

    2011-01-01

    The beam deformation equation has very wide applications in structural engineering. As a differential equation, it has its own problem concerning existence, uniqueness and methods of solutions. Often, original forms of governing differential equations used in engineering problems are simplified...... Method (OHAM). The comparisons of the results reveal that these methods are very effective, convenient and quite accurate to systems of non-linear differential equation......., and this process produces noise in the obtained answers. This paper deals with solution of second order of differential equation governing beam deformation using four analytical approximate methods, namely the Homotopy Perturbation Method (HPM), Variational Iteration Method (VIM) and Optimal Homotopy Asymptotic...

  12. Investigating the patterns and determinants of seasonal variation in vitamin D status in Australian adults: the Seasonal D Cohort Study

    Directory of Open Access Journals (Sweden)

    Laura King

    2016-08-01

    Full Text Available Abstract Background Vitamin D status generally varies seasonally with changing solar UVB radiation, time in the sun, amount of skin exposed, and, possibly, diet. The Seasonal D Study was designed to quantify the amplitude and phase of seasonal variation in the serum concentration of 25-hydroxyvitamin D, (25OHD and identify the determinants of the amplitude and phase and those of inter-individual variability in seasonal pattern. Methods The Seasonal D Study collected data 2-monthly for 12 months, including demographics, personal sun exposure using a diary and polysulphone dosimeters over 7 days, and blood for serum 25(OHD concentration. The study recruited 333 adults aged 18–79 years living in Canberra (35°S, n = 168 and Brisbane (27°South, n = 165, Australia. Discussion We report the study design and cohort description for the Seasonal D Study. The study has collected a wealth of data to examine inter- and intra-individual seasonal variation in vitamin D status and serum 25(OHD levels in Australian adults.

  13. Investigation on a system to collect water vapor from the air, for the analysis of natural isotopic variation

    International Nuclear Information System (INIS)

    Foloni, L.L.

    1975-01-01

    The development of a system to collect water vapor from air for isotopic composition analysis and its natural variation is studied. The system consists of a molecular sieve type 4A, without cooling agent and permits the choice of a sampling time varying from a few minutes to many hours through the control of the admission vapor flux. The system has been compared with other existing systems, having shown excellent performance for the collection of samples for D/H ratio analysis, with errors of the order of +- -+ 3.0 0 /oo and +- -+ 0.6 0 /oo in the delta sub(D) 0 /oo and delta 18 0 0 /oo ratios, respectively [pt

  14. Experimental investigation on the effect of intake air temperature and air-fuel ratio on cycle-to-cycle variations of HCCI combustion and performance parameters

    Energy Technology Data Exchange (ETDEWEB)

    Maurya, Rakesh Kumar; Agarwal, Avinash Kumar [Engine Research Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Kanpur, Kanpur 208016 (India)

    2011-04-15

    Combustion in HCCI engines is a controlled auto ignition of well-mixed fuel, air and residual gas. Since onset of HCCI combustion depends on the auto ignition of fuel/air mixture, there is no direct control on the start of combustion process. Therefore, HCCI combustion becomes unstable rather easily, especially at lower and higher engine loads. In this study, cycle-to-cycle variations of a HCCI combustion engine fuelled with ethanol were investigated on a modified two-cylinder engine. Port injection technique is used for preparing homogeneous charge for HCCI combustion. The experiments were conducted at varying intake air temperatures and air-fuel ratios at constant engine speed of 1500 rpm and P-{theta} diagram of 100 consecutive combustion cycles for each test conditions at steady state operation were recorded. Consequently, cycle-to-cycle variations of the main combustion parameters and performance parameters were analyzed. To evaluate the cycle-to-cycle variations of HCCI combustion parameters, coefficient of variation (COV) of every parameter were calculated for every engine operating condition. The critical optimum parameters that can be used to define HCCI operating ranges are 'maximum rate of pressure rise' and 'COV of indicated mean effective pressure (IMEP)'. (author)

  15. The temporal subsoil radon variation as indicator and forerunner of the geodynamical catastrophes: Experience of long period experimental investigations

    International Nuclear Information System (INIS)

    Rudakov, V.P.

    1996-01-01

    The emanation (radon) method was one of the non-traditional methods, which being used for the radiometric prospecting, have been used as for the investigations of the geodynamical processes, (earthquakes, volcano eruption e.a.), so for investigations of the local geodynamical processes such as landslips, rock burstings and gas in the mines, provoked seismicity and so on. Now this method very effectively is used for the investigation of the different processes in civil and industrial building, structure-geodynamical mapping on the prognostic grounds and of the oil-gas deposits, in prediction of the earthquakes and in the control of the radioecological situation of the atomic stations environments. (author). 10 refs, 7 figs

  16. Investigation into the Mpemba Effect: Variation in the Freezing Time of Water Dependent on Initial Temperature and Purity

    Science.gov (United States)

    Thvedt, Ingrid; Roseberry, Martha; Lehman, Susan

    2009-03-01

    The observation that hot water sometimes appears to freeze more quickly than cold water, known as the Mpemba effect, has generated vigorous debate. Prior research [1] into the Mpemba effect has resulted in conflicting results, due to a variety of observation techniques, multiple definitions of freezing, and different water treatments. To clarify the previous results, we have tested multiple types of water and improved the sample monitoring. During cooling and freezing, each 50 g water sample is continually monitored by three thermistors at different depths. Samples of tap, distilled, and nanopure water were heated, heated and cooled, or boiled before being frozen. We monitor the time to reach freezing, the duration of freezing, and the total time to reach -7^oC. We observe the Mpemba effect most consistently in the length of the freezing transition in tap water. Observations of temperature variation during freezing will also be presented. [1] See the review by M. Jeng, Am.J.Phys. 74 514 (2006).

  17. Investigation of Primary Factors Affecting the Variation of Modeled Oak Pollen Concentrations: A Case Study for Southeast Texas in 2010

    Science.gov (United States)

    Jeon, Wonbae; Choi, Yunsoo; Roy, Anirban; Pan, Shuai; Price, Daniel; Hwang, Mi-Kyoung; Kim, Kyu Rang; Oh, Inbo

    2018-02-01

    Oak pollen concentrations over the Houston-Galveston-Brazoria (HGB) area in southeastern Texas were modeled and evaluated against in-situ data. We modified the Community Multi-scale Air Quality (CMAQ) model to include oak pollen emission, dispersion, and deposition. The Oak Pollen Emission Model (OPEM) calculated gridded oak pollen emissions, which are based on a parameterized equation considering a plant-specific factor ( C e ), surface characteristics, and meteorology. The simulation period was chosen to be February 21 to April 30 in the spring of 2010, when the observed monthly mean oak pollen concentrations were the highest in six years (2009-2014). The results indicated C e and meteorology played an important role in the calculation of oak pollen emissions. While C e was critical in determining the magnitude of oak pollen emissions, meteorology determined their variability. In particular, the contribution of the meteorology to the variation in oak pollen emissions increased with the oak pollen emission rate. The evaluation results using in-situ surface data revealed that the model underestimated pollen concentrations and was unable to accurately reproduce the peak pollen episodes. The model error was likely due to uncertainty in climatology-based C e used for the estimation of oak pollen emissions and inaccuracy in the wind fields from the Weather Research and Forecast (WRF) model.

  18. Fatores associados à hipotermia durante o transporte intra-hospitalar em pacientes internados em Unidade de Terapia Intensiva Neonatal Pequeño para la edad gestacional: repercusión en las habilidades motoras finas Factors associated with hypothermia during intra-hospital transport in patients assisted in a Neonatal Intensive Care Unit

    Directory of Open Access Journals (Sweden)

    Anna Luiza P. Vieira

    2011-03-01

    transporte fueron estudiados por regresión logística. RESULTADOS: De los 1197 transportes realizados en el periodo de estudio, 1191 (99,5% atendieron a los criterios de inclusión. Las enfermedades de base de los 640 niños estudiados (edad gestacional: 35,0±3,8sem; peso al nacer: 2341±888g fueron: malformaciones únicas o múltiples (71%, infecciones (7,7%, hemorragia peri/intraventricular (5,5%, angustia respiratoria (4,0% y otros (11,8%. Los pacientes fueron transportados para realización de cirugías (22,6%, resonancia magnética (10,6%, tomografía (20,9%, exámenes contrastados (18,2% y otros procedimientos (27,7%. La hipotermia ocurrió en 182 (15,3% transportes y se asoció al (OR; IC95%: peso al transporte OBJECTIVE: To determine frequency and factors associated with hypothermia during intra-hospital transports of patients assisted in a neonatal intensive care unit (NICU. METHODS: Cross-sectional study nested in a prospective cohort of infants submitted to intra-hospital transports performed by a trained team from January 1997 to December 2008 at a NICU of a public university hospital. Transports of patients aged more than one year and/or with weight higher than 10kg were excluded. Factors associated with hypothermia during intra-hospital transports were studied by logistic regression analysis. RESULTS: Among the 1,197 transports performed during the studied period, 1,191 (99.5% met the inclusion criteria. The 640 transported infants had mean gestational age of 35.0±3.8 weeks and birth weight of 2341±888g. They presented the following underline diseases: single or multiple malformations (71.0%, infections (7.7%, peri/intraventricular hemorrhage (5.5%, respiratory distress (4.0% and others (11.1%. Patients were transported for surgical procedures (22.6%, magnetic resonance (10.6%, tomography imaging (20.9%, contrasted exams (18.2%, and others (27.7%. Hypothermia occurred in 182 (15.3% transports and was associated with (OR; 95%CI: weight at transport <1000g (3

  19. A geostatistical investigation of the spatial variation of external gamma exposure in urban area of Pocos de Caldas Plateau

    International Nuclear Information System (INIS)

    Silva, Nivaldo C.; Macacini, Jose F.; Taddei, Maria H.T.; Montano, Marcelo; Fontes, Aurelio T.

    2008-01-01

    Full text: The Pocos de Caldas Plateau has been recognized as High Level of Natural Radiation Area for a long time. It consists in an alkaline intrusion with some uranium and thorium anomalies, where the first Brazilian uranium mining and milling facilities is located. Due to these facts, the population of Pocos de Caldas city shows a great deal of concern about radiation health effects. This perception of the risks of radiation exposure leads to much confusion among the population that attributes an imaginary excess (without an scientific support) of cancer cases and deformities in newborns in the city to radiation. In order to obtain information for help radiation risks management by government and to explore the spatial variation external gamma exposure a survey in the urban area of Pocos de Caldas city was done. The measurements were performed using a Mobile Radioactivity Measurement System - Mobisys (ESM Eberline model FHT 1376). The system consists of a high-sensitivity 5-liter scintillation detector, an electronic for measurement system that is able to on-line separate natural and artificial gamma radiation (Natural Background Rejection Detector NBR), one compact Global Positioning System GPS and a computer (notebook). Data was collected at approximately 50,000 points spread over all streets of city. The obtained results ranged from 40 nSv.h -1 to 420 nSv.h -1 where the mean value was 112 nSv.h -1 . The spatial distribution of gamma exposure over the city is quite homogeneous with lowest and highest values in western and southern area, respectively. (author)

  20. Investigation of regional geohydrology south of Great Slave Lake, Canada, utilizing natural sulphur and hydrogen isotope variations

    International Nuclear Information System (INIS)

    Weyer, K.U.; Horwood, W.C.; Krouse, H.R.

    1979-01-01

    The well-defined topographic, geological, and orographic setting in the area south of Great Slave Lake, in Canada's North-West Territory (N.W.T.), is favourable for a meaningful investigation of the local and regional groundwater flow sysems in the area of the Mississippi Valley type lead-zinc deposits at Pine Point. Chemical and isotope (delta 34 S, deltaD) investigations have provided supporting evidence for conceptual models of groundwater flow. The range of the deltaD values encountered (-111 to -205 per mille SMOW) indicates that the hydrodynamic systems convey meteoric waters. Differences in deltaD values of water samples were used to elucidate the hydrological relationship between groundwater and a major river in a karst area. The ore bodies at Pine Point are engulfed in a reducing hydrosphere. Sulphur species, derived from gypsum layers by regional groundwater flow, are instrumental in maintaining the reducing conditions. There is evidence that the reduction of sulphate to sulphide is caused by bacteria. Microbiological sulphate reduction, rather than isotopic exchange processes, is also responsible for shifts of measured delta 34 S values in dissolved sulphates. After correction for those shifts, four different sources for dissolved sulphate were identified. In addition to supporting the conceptual model of regional groundwater flow in this area, the isotopic data also help to delineate hydrological features on a more local scale. (author)

  1. Investigating the temporal variations of the time-clustering behavior of the Koyna-Warna (India) reservoir-triggered seismicity

    International Nuclear Information System (INIS)

    Telesca, Luciano

    2011-01-01

    Research highlights: → Time-clustering behaviour in seismicity can be detected by applying the Allan Factor. → The reservoir-induced seismicity at Koyna-Warna (India) is time-clusterized. → Pre- and co-seismic increases of the time-clustering degree are revealed. - Abstract: The time-clustering behavior of the 1996-2005 seismicity of Koyna-Warna region (India), a unique site where reservoir-triggered earthquakes have been continuously occurring over the last about 50 year, has been analyzed. The scaling exponent α, estimated by using the Allan Factor method, a powerful tool to investigate clusterization in point processes, shows co-seismic and pre-seismic enhancements associated with the occurrence of the major events.

  2. Investigation of plasma parameters at BATMAN for variation of the Cs evaporation asymmetry and comparing two driver geometries

    Science.gov (United States)

    Wimmer, C.; Fantz, U.; Aza, E.; Jovović, J.; Kraus, W.; Mimo, A.; Schiesko, L.

    2017-08-01

    The Neutral Beam Injection (NBI) system for fusion devices like ITER and, beyond ITER, DEMO requires large scale sources for negative hydrogen ions. BATMAN (Bavarian Test Machine for Negative ions) is a test facility attached with the prototype source for the ITER NBI (1/8 source size of the ITER source), dedicated to physical investigations due to its flexible access for diagnostics and exchange of source components. The required amount of negative ions is produced by surface conversion of hydrogen atoms or ions on caesiated surfaces. Several diagnostic tools (Optical Emission Spectroscopy, Cavity Ring-Down Spectroscopy for H-, Langmuir probes, Tunable Diode Laser Absorption Spectroscopy for Cs) allow the determination of plasma parameters in the ion source. Plasma parameters for two modifications of the standard prototype source have been investigated: Firstly, a second Cs oven has been installed in the bottom part of the back plate in addition to the regularly used oven in the top part of the back plate. Evaporation from the top oven only can lead to a vertically asymmetric Cs distribution in front of the plasma grid. Using both ovens, a symmetric Cs distribution can be reached - however, in most cases no significant change of the extracted ion current has been determined for varying Cs symmetry if the source is well-conditioned. Secondly, BATMAN has been equipped with a much larger, racetrack-shaped RF driver (area of 32×58 cm2) instead of the cylindrical RF driver (diameter of 24.5 cm). The main idea is that one racetrack driver could substitute two cylindrical drivers in larger sources with increased reliability and power efficiency. For the same applied RF power, the electron density is lower in the racetrack driver due to its five times higher volume. The fraction of hydrogen atoms to molecules, however, is at a similar level or even slightly higher, which is a promising result for application in larger sources.

  3. Compositional Variation and Bioactivity of the Leaf Essential Oil of Montanoa guatemalensis from Monteverde, Costa Rica: A Preliminary Investigation

    Directory of Open Access Journals (Sweden)

    Victoria D. Flatt

    2015-11-01

    Full Text Available Background: Montanoa guatemalensis is a small to medium-sized tree in the Asteraceae that grows in Central America from Mexico south through Costa Rica. There have been no previous investigations on the essential oil of this tree. Methods: The leaf essential oils of M. guatemalensis were obtained from different individual trees growing in Monteverde, Costa Rica, in two different years, and were analyzed by gas chromatography—mass spectrometry. Results: The leaf oils from 2008 were rich in sesquiterpenoids, dominated by α-selinene, β-selinene, and cyclocolorenone, with lesser amounts of the monoterpenes α-pinene and limonene. In contrast, the samples from 2009 showed no α- or β-selinene, but large concentrations of trans-muurola-4(14,5-diene, β-cadinene, and cyclocolorenone, along with greater concentrations of α-pinene and limonene. The leaf oils were screened for cytotoxic and antimicrobial activities and did show selective cytotoxic activity on MDA-MB-231 breast tumor cells. Conclusion: M. guatemalensis leaf oil, rich in cyclocolorenone, α-selinene, and β-selinene, showed selective in vitro cytotoxic activity to MDA-MB-231 cells. The plant may be a good source of cyclocolorenone.

  4. Serotonin and Dopamine Gene Variation and Theory of Mind Decoding Accuracy in Major Depression: A Preliminary Investigation.

    Science.gov (United States)

    Zahavi, Arielle Y; Sabbagh, Mark A; Washburn, Dustin; Mazurka, Raegan; Bagby, R Michael; Strauss, John; Kennedy, James L; Ravindran, Arun; Harkness, Kate L

    2016-01-01

    Theory of mind-the ability to decode and reason about others' mental states-is a universal human skill and forms the basis of social cognition. Theory of mind accuracy is impaired in clinical conditions evidencing social impairment, including major depressive disorder. The current study is a preliminary investigation of the association of polymorphisms of the serotonin transporter (SLC6A4), dopamine transporter (DAT1), dopamine receptor D4 (DRD4), and catechol-O-methyl transferase (COMT) genes with theory of mind decoding in a sample of adults with major depression. Ninety-six young adults (38 depressed, 58 non-depressed) completed the 'Reading the Mind in the Eyes task' and a non-mentalistic control task. Genetic associations were only found for the depressed group. Specifically, superior accuracy in decoding mental states of a positive valence was seen in those homozygous for the long allele of the serotonin transporter gene, 9-allele carriers of DAT1, and long-allele carriers of DRD4. In contrast, superior accuracy in decoding mental states of a negative valence was seen in short-allele carriers of the serotonin transporter gene and 10/10 homozygotes of DAT1. Results are discussed in terms of their implications for integrating social cognitive and neurobiological models of etiology in major depression.

  5. Serotonin and Dopamine Gene Variation and Theory of Mind Decoding Accuracy in Major Depression: A Preliminary Investigation.

    Directory of Open Access Journals (Sweden)

    Arielle Y Zahavi

    Full Text Available Theory of mind-the ability to decode and reason about others' mental states-is a universal human skill and forms the basis of social cognition. Theory of mind accuracy is impaired in clinical conditions evidencing social impairment, including major depressive disorder. The current study is a preliminary investigation of the association of polymorphisms of the serotonin transporter (SLC6A4, dopamine transporter (DAT1, dopamine receptor D4 (DRD4, and catechol-O-methyl transferase (COMT genes with theory of mind decoding in a sample of adults with major depression. Ninety-six young adults (38 depressed, 58 non-depressed completed the 'Reading the Mind in the Eyes task' and a non-mentalistic control task. Genetic associations were only found for the depressed group. Specifically, superior accuracy in decoding mental states of a positive valence was seen in those homozygous for the long allele of the serotonin transporter gene, 9-allele carriers of DAT1, and long-allele carriers of DRD4. In contrast, superior accuracy in decoding mental states of a negative valence was seen in short-allele carriers of the serotonin transporter gene and 10/10 homozygotes of DAT1. Results are discussed in terms of their implications for integrating social cognitive and neurobiological models of etiology in major depression.

  6. Maternal BMI and diabetes in pregnancy: Investigating variations between ethnic groups using routine maternity data from London, UK.

    Science.gov (United States)

    Nishikawa, Erin; Oakley, Laura; Seed, Paul T; Doyle, Pat; Oteng-Ntim, Eugene

    2017-01-01

    To investigate the ethnicity-specific association between body mass index (BMI) and diabetes in pregnancy, with a focus on the appropriateness of using BMI cut-offs to identify pregnant women at risk of diabetes. Analysis of routinely-collected data from a maternity unit in London, UK. Data were available on 53 264 women delivering between 2004 and 2012. Logistic regression was used to explore the association between diabetes in pregnancy and BMI among women of different ethnicities, and adjusted probability estimates were used to derive risk equivalent cut-offs. ROC curve analysis was used to assess the performance of BMI as a predictor of diabetes in pregnancy. The prevalence of diabetes in pregnancy was 2.3% overall; highest in South and East Asian women (4.6% and 3.7%). In adjusted analysis, BMI category was strongly associated with diabetes in all ethnic groups. Modelled as a continuous variable with a quadratic term, BMI was an acceptable predictor of diabetes according to ROC curve analysis. Applying a BMI cut-off of 30 kg/m2 would identify just over half of Black women with diabetes in pregnancy, a third of White (32%) and South Asian (35%) women, but only 13% of East Asian women. The 'risk equivalent' (comparable to 30 kg/m2 in White women) threshold for South Asian and East Asian women was approximately 21 kg/m2, and 27.5 kg/m2 for Black women. This study suggests that current BMI thresholds are likely to be ineffective for diabetes screening in South and East Asian women, as many cases of diabetes will occur at low BMI levels. Our results suggest that East Asian women appear to face a similarly high risk of diabetes to South Asian women. Current UK guidelines recommend diabetes screening should be offered to all pregnant South Asian women; extending this recommendation to include women of East Asian ethnicity may be appropriate.

  7. Investigation of Catalytic Effects and Compositional Variations in Desorption Characteristics of LiNH2-nanoMgH2

    Directory of Open Access Journals (Sweden)

    Sesha S. Srinivasan

    2017-07-01

    Full Text Available LiNH2 and a pre-processed nanoMgH2 with 1:1 and 2:1 molar ratios were mechano-chemically milled in a high-energy planetary ball mill under inert atmosphere, and at room temperature and atmospheric pressure. Based on the thermogravimetric analysis (TGA experiments, 2LiNH2-nanoMgH2 demonstrated superior desorption characteristics when compared to the LiNH2-nanoMgH2. The TGA studies also revealed that doping 2LiNH2-nanoMgH2 base material with 2 wt. % nanoNi catalyst enhances the sorption kinetics at lower temperatures. Additional investigation of different catalysts showed improved reaction kinetics (weight percentage of H2 released per minute of the order TiF3 > nanoNi > nanoTi > nanoCo > nanoFe > multiwall carbon nanotube (MWCNT, and reduction in the on-set decomposition temperatures of the order nanoCo > TiF3 > nanoTi > nanoFe > nanoNi > MWCNT for the base material 2LiNH2-nanoMgH2. Pristine and catalyst-doped 2LiNH2-nanoMgH2 samples were further probed by X-ray diffraction, Fourier transform infrared spectroscopy, transmission and scanning electron microscopies, thermal programmed desorption and pressure-composition-temperature measurements to better understand the improved performance of the catalyst-doped samples, and the results are discussed.

  8. Monte Carlo Investigation of Photon Beam Characteristics and its Variation with Incident Electron Beam Parameters for Indigenous Medical Linear Accelerator.

    Science.gov (United States)

    Mishra, Subhalaxmi; Dixit, P K; Selvam, T Palani; Yavalkar, Sanket S; Deshpande, D D

    2018-01-01

    A Monte Carlo model of a 6 MV medical linear accelerator (linac) unit built indigenously was developed using the BEAMnrc user code of the EGSnrc code system. The model was benchmarked against the measurements. Monte Carlo simulations were carried out for different incident electron beam parameters in the study. Simulation of indigenously developed linac unit has been carried out using the Monte Carlo based BEAMnrc user-code of the EGSnrc code system. Using the model, percentage depth dose (PDD), and lateral dose profiles were studied using the DOSXYZnrc user code. To identify appropriate electron parameters, three different distributions of electron beam intensity were investigated. For each case, the kinetic energy of the incident electron was varied from 6 to 6.5 MeV (0.1 MeV increment). The calculated dose data were compared against the measurements using the PTW, Germany make RFA dosimetric system (water tank MP3-M and 0.125 cm 3 ion chamber). The best fit of incident electron beam parameter was found for the combination of beam energy of 6.2 MeV and circular Gaussian distributed source in X and Y with FWHM of 1.0 mm. PDD and beam profiles (along both X and Y directions) were calculated for the field sizes from 5 cm × 5 cm to 25 cm × 25 cm. The dose difference between the calculated and measured PDD and profile values were under 1%, except for the penumbra region where the maximum deviation was found to be around 2%. A Monte Carlo model of indigenous linac (6 MV) has been developed and benchmarked against the measured data.

  9. Investigation of variations in the acrylamide and N(ε) -(carboxymethyl) lysine contents in cookies during baking.

    Science.gov (United States)

    Cheng, Lu; Jin, Cheng; Zhang, Ying

    2014-05-01

    Baking processing is indispensable to determine special sensory prosperities of cookies and induces the formation of some beneficial components such as antioxidants. However, the formation of some Maillard reaction-derived chemical hazards, such as acrylamide (AA) and N(ε) -(carboxymethyl) lysine (CML) in cookies is also a significant consequence of baking processing from a food safety standpoint. This study investigated the effects of baking conditions on the formation of AA and CML, as well as the antioxidant activity (AOA) of cookies. Cookies were baked at various baking temperatures (155 to 230 °C) and times (1.5 to 31 min). AA and CML contents were determined by ultra-performance liquid chromatography-tandem mass spectrometry, respectively. The highest level of AA was obtained in the cookies baked at 155 °C/21 min and 205 °C/11 min (328.93 ± 3.10 μg/kg and 329.29 ± 5.29 μg/kg), while the highest level of CML was obtained in the cookies baked at 230 °C/1.5 min (118.05 ± 0.21 mg/kg). AA was prone to form at relatively low temperature range (155 to 205 °C), however, CML at relatively high temperature range (205 to 230 °C). The CML content was much higher than the AA content in the same set of cookies, by about 2 to 3 orders of magnitude. The AOA of cookies increased at more severe baking conditions. According to the AA and CML content, AOA and sensory properties of cookies, the temperature-time regime of 180 °C/16 min might be a compromised selection. However, only optimizing the baking condition was not enough for manufacture of high-quality cookies. Cookies, a kind of widely consumed bakery products in the world, contain some potentially harmful compounds, like acrylamide (AA) and N(ε) -(carboxymethyl) lysine (CML). AA in cookies has led to public health concern and several research efforts. But CML, another Maillard reaction-derived chemical hazard, has been neglected so far, even though its content is much higher than that of AA in cookies. The

  10. An investigation of the inter-clonal variation of the interactive effects of cadmium and Microcystis aeruginosa on the reproductive performance of Daphnia magna

    International Nuclear Information System (INIS)

    De Coninck, Dieter I.M.; Janssen, Colin R.; De Schamphelaere, Karel A.C.

    2013-01-01

    Highlights: •Interaction of a metal and cyanobacterium in 20 genetically distinct waterflea clones. •All observed effects were non-interactive. •This contrasted expectations based on shared modes of toxic action. -- Abstract: Interactive effects between chemical and natural stressors as well as genetically determined variation in stress tolerance among individuals may complicate risk assessment and management of chemical pollutants in natural ecosystems. Although genetic variation in tolerance to single stressors has been described extensively, genetic variation in interactive effects between two stressors has only rarely been investigated. Here, we examined the interactive effects between a chemical stressor (Cd) and a natural stressor (the cyanobacteria Microcystis aeruginosa) on the reproduction of Daphnia magna in 20 genetically different clones using a full-factorial experimental design and with the independent action model of joint stressor action as the reference theoretical framework. Across all clones, the reduction of 21-day reproduction compared to the control treatment (no Cd, no M. aeruginosa) ranged from −10% to 98% following Cd exposure alone, from 44% to 89% for Microcystis exposure alone, and from 61% to 98% after exposure to Cd + Microcystis combined. Three-way ANOVA on log-transformed reproduction data of all clones together did not detect a statistically significant Cd × Microcystis interaction term (F-test, p = 0.11), meaning that on average both stressors do not interact in inhibiting reproductive performance of D. magna. This finding contrasted expectations based on some known shared mechanisms of toxicity of Cd and Microcystis and therefore cautions against making predictions of interactive chemical + natural stressor effects from incomplete knowledge on affected biological processes and pathways. Further, still based on three-way ANOVA, we did not find statistically significant clone × Cd × Microcystis interaction when data for

  11. An investigation of the inter-clonal variation of the interactive effects of cadmium and Microcystis aeruginosa on the reproductive performance of Daphnia magna

    Energy Technology Data Exchange (ETDEWEB)

    De Coninck, Dieter I.M., E-mail: Dieter.DeConinck@UGent.be; Janssen, Colin R.; De Schamphelaere, Karel A.C.

    2013-09-15

    Highlights: •Interaction of a metal and cyanobacterium in 20 genetically distinct waterflea clones. •All observed effects were non-interactive. •This contrasted expectations based on shared modes of toxic action. -- Abstract: Interactive effects between chemical and natural stressors as well as genetically determined variation in stress tolerance among individuals may complicate risk assessment and management of chemical pollutants in natural ecosystems. Although genetic variation in tolerance to single stressors has been described extensively, genetic variation in interactive effects between two stressors has only rarely been investigated. Here, we examined the interactive effects between a chemical stressor (Cd) and a natural stressor (the cyanobacteria Microcystis aeruginosa) on the reproduction of Daphnia magna in 20 genetically different clones using a full-factorial experimental design and with the independent action model of joint stressor action as the reference theoretical framework. Across all clones, the reduction of 21-day reproduction compared to the control treatment (no Cd, no M. aeruginosa) ranged from −10% to 98% following Cd exposure alone, from 44% to 89% for Microcystis exposure alone, and from 61% to 98% after exposure to Cd + Microcystis combined. Three-way ANOVA on log-transformed reproduction data of all clones together did not detect a statistically significant Cd × Microcystis interaction term (F-test, p = 0.11), meaning that on average both stressors do not interact in inhibiting reproductive performance of D. magna. This finding contrasted expectations based on some known shared mechanisms of toxicity of Cd and Microcystis and therefore cautions against making predictions of interactive chemical + natural stressor effects from incomplete knowledge on affected biological processes and pathways. Further, still based on three-way ANOVA, we did not find statistically significant clone × Cd × Microcystis interaction when data for

  12. Beyond Punnett Squares: Student Word Association and Explanations of Phenotypic Variation through an Integrative Quantitative Genetics Unit Investigating Anthocyanin Inheritance and Expression in "Brassica rapa" Fast Plants

    Science.gov (United States)

    Batzli, Janet M.; Smith, Amber R.; Williams, Paul H.; McGee, Seth A.; Dosa, Katalin; Pfammatter, Jesse

    2014-01-01

    Genetics instruction in introductory biology is often confined to Mendelian genetics and avoids the complexities of variation in quantitative traits. Given the driving question "What determines variation in phenotype (Pv)? (Pv=Genotypic variation Gv + environmental variation Ev)," we developed a 4-wk unit for an inquiry-based laboratory…

  13. Intra-hospital use of a telepathology system.

    Science.gov (United States)

    Ongürü, O; Celasun, B

    2000-01-01

    Utilization of telepathology systems to cover distant geographical areas has increased recently. However, the potential usefulness of similar systems for closer distances does not seem to be widely appreciated. In this study, we present data on the use of a simple telepathology system connecting the pathology department and the intra-operative consultation room within the operating theaters of the hospital. Ninety-eight frozen section cases from a past period have been re-evaluated using a real-time setup. Forty-eight of the cases have been re-evaluated in the customary fashion; allowing both ends to communicate and cooperate freely. Fifty of the cases, however, were evaluated by the consultant while the operating room end behaved like a robot; moving the stage of the microscope, changing and focusing the objectives. The deferral rate was lower than the original frozen section evaluations. Overall, the sensitivity was 100%, specificity 98%, negative predictive value 96, 5% and positive predictive value 100%. No significant difference was found for the diagnostic performances between the cooperative and robotic simulation methods.Our results strengthen the belief that telepathology is a valuable tool in offering pathology services to remote areas. The far side of a hospital building can also be a remote area and a low cost system can be helpful for intraoperative consultations. Educational value of such a system is also commendable.

  14. Combining Unsteady Blade Pressure Measurements and a Free-Wake Vortex Model to Investigate the Cycle-to-Cycle Variations in Wind Turbine Aerodynamic Blade Loads in Yaw

    Directory of Open Access Journals (Sweden)

    Moutaz Elgammi

    2016-06-01

    Full Text Available Prediction of the unsteady aerodynamic flow phenomenon on wind turbines is challenging and still subject to considerable uncertainty. Under yawed rotor conditions, the wind turbine blades are subjected to unsteady flow conditions as a result of the blade advancing and retreating effect and the development of a skewed vortical wake created downstream of the rotor plane. Blade surface pressure measurements conducted on the NREL Phase VI rotor in yawed conditions have shown that dynamic stall causes the wind turbine blades to experience significant cycle-to-cycle variations in aerodynamic loading. These effects were observed even though the rotor was subjected to a fixed speed and a uniform and steady wind flow. This phenomenon is not normally predicted by existing dynamic stall models integrated in wind turbine design codes. This paper couples blade pressure measurements from the NREL Phase VI rotor to a free-wake vortex model to derive the angle of attack time series at the different blade sections over multiple rotor rotations and three different yaw angles. Through the adopted approach it was possible to investigate how the rotor self-induced aerodynamic load fluctuations influence the unsteady variations in the blade angles of attack and induced velocities. The hysteresis loops for the normal and tangential load coefficients plotted against the angle of attack were plotted over multiple rotor revolutions. Although cycle-to-cycle variations in the angles of attack at the different blade radial locations and azimuth positions are found to be relatively small, the corresponding variations in the normal and tangential load coefficients may be significant. Following a statistical analysis, it was concluded that the load coefficients follow a normal distribution at the majority of blade azimuth angles and radial locations. The results of this study provide further insight on how existing engineering models for dynamic stall may be improved through

  15. Investigating the Influence of Box-Constraints on the Solution of a Total Variation Model via an Efficient Primal-Dual Method

    Directory of Open Access Journals (Sweden)

    Andreas Langer

    2018-01-01

    Full Text Available In this paper, we investigate the usefulness of adding a box-constraint to the minimization of functionals consisting of a data-fidelity term and a total variation regularization term. In particular, we show that in certain applications an additional box-constraint does not effect the solution at all, i.e., the solution is the same whether a box-constraint is used or not. On the contrary, i.e., for applications where a box-constraint may have influence on the solution, we investigate how much it effects the quality of the restoration, especially when the regularization parameter, which weights the importance of the data term and the regularizer, is chosen suitable. In particular, for such applications, we consider the case of a squared L 2 data-fidelity term. For computing a minimizer of the respective box-constrained optimization problems a primal-dual semi-smooth Newton method is presented, which guarantees superlinear convergence.

  16. Red shift, blue shift: investigating Doppler shifts, blubber thickness, and migration as explanations of seasonal variation in the tonality of Antarctic blue whale song.

    Directory of Open Access Journals (Sweden)

    Brian S Miller

    Full Text Available The song of Antarctic blue whales (Balaenoptera musculus intermedia comprises repeated, stereotyped, low-frequency calls. Measurements of these calls from recordings spanning many years have revealed a long-term linear decline as well as an intra-annual pattern in tonal frequency. While a number of hypotheses for this long-term decline have been investigated, including changes in population structure, changes in the physical environment, and changes in the behaviour of the whales, there have been relatively few attempts to explain the intra-annual pattern. An additional hypothesis that has not yet been investigated is that differences in the observed frequency from each call are due to the Doppler effect. The assumptions and implications of the Doppler effect on whale song are investigated using 1 vessel-based acoustic recordings of Antarctic blue whales with simultaneous observation of whale movement and 2 long-term acoustic recordings from both the subtropics and Antarctic. Results from vessel-based recordings of Antarctic blue whales indicate that variation in peak-frequency between calls produced by an individual whale was greater than would be expected by the movement of the whale alone. Furthermore, analysis of intra-annual frequency shift at Antarctic recording stations indicates that the Doppler effect is unlikely to fully explain the observations of intra-annual pattern in the frequency of Antarctic blue whale song. However, data do show cyclical changes in frequency in conjunction with season, thus suggesting that there might be a relationship among tonal frequency, body condition, and migration to and from Antarctic feeding grounds.

  17. Investigation of the variation of the specific heat capacity of local soil samples from the Niger delta, Nigeria with moisture content

    International Nuclear Information System (INIS)

    Ofoegbu, C.O.; Adjepong, S.K.

    1987-11-01

    Results of an investigation of the variation, with moisture content, of the specific heat capacity of samples of three texturally different types of soil (clayey, sandy and sandy loam) obtained from the Niger delta area of Nigeria, are presented. The results show that the specific heat capacities of the soils studied, increase with moisture content. This increase is found to be linear for the entire range of moisture contents considered (0-25%), in the case of the sandy loam soil while for the clayey and sandy soils the specific heat capacity is found to increase linearly with moisture content up to about 15% after which the increase becomes parabolic. The rate of increase of specific heat capacity with moisture content appears to be highest in the clayey soil and lowest in the sandy soil. It is thought that the differences in the rates of increase of specific heat capacity with moisture content, observed for the soils, reflect the soils' water-retention capacities. (author) 3 refs, 5 figs

  18. Investigating the relationship between costs and outcomes for English mental health providers: a bi-variate multi-level regression analysis.

    Science.gov (United States)

    Moran, Valerie; Jacobs, Rowena

    2018-06-01

    Provider payment systems for mental health care that incentivize cost control and quality improvement have been a policy focus in a number of countries. In England, a new prospective provider payment system is being introduced to mental health that should encourage providers to control costs and improve outcomes. The aim of this research is to investigate the relationship between costs and outcomes to ascertain whether there is a trade-off between controlling costs and improving outcomes. The main data source is the Mental Health Minimum Data Set (MHMDS) for the years 2011/12 and 2012/13. Costs are calculated using NHS reference cost data while outcomes are measured using the Health of the Nation Outcome Scales (HoNOS). We estimate a bivariate multi-level model with costs and outcomes simultaneously. We calculate the correlation and plot the pairwise relationship between residual costs and outcomes at the provider level. After controlling for a range of demographic, need, social, and treatment variables, residual variation in costs and outcomes remains at the provider level. The correlation between residual costs and outcomes is negative, but very small, suggesting that cost-containment efforts by providers should not undermine outcome-improving efforts under the new payment system.

  19. Variation in risk indicators of cardiovascular disease during the menstrual cycle: an investigation of within-subject variations in glutathione peroxidase, haemostatic variables, lipids and lipoproteins in healthy young women

    DEFF Research Database (Denmark)

    Larsen, L F; Andersen, H R; Hansen, A B

    1996-01-01

    Variations in erythrocyte glutathione peroxidase activity, serum concentrations of lipids and lipoproteins and in blood coagulation and fibrinolysis during the menstrual cycle were studied in healthy young women. Blood samples were drawn twice a week for 9 weeks. A group of males was used...

  20. Diurnal pH variations of a Glacial Stream: a starting point for Inquiry-driven student and teacher Investigations of a Glacial Ecosystem

    Science.gov (United States)

    O'Brien, W. P.; Galbraith, J.; Fatland, D. R.; Heavner, M.

    2009-12-01

    Contemporary geoscience research often operates in a mode that generates huge repositories of data available on the internet to the scientific community and the general public. The SEAMONSTER (SM) online data browser of both archival and real-time data is an example of such a dynamic online ecosystem resource associated with the Juneau Icefield. Although newly developed database navigation tools and geobrowsers make it easy for non-experts to access data of interest, it nonetheless can be daunting to K-16 educators to fashion lesson plans that make effective use of these rich resources. In the following scenario, a student and associated teacher, operating outside the traditional didactic lecture/demo mode, explore and try to make sense of a tiny portion of SM data in a spirit of inquiry guided by curiosity, looking for features that catch their attention as they skim through interactive time-series graphs (96 samples/day) of data from Lemon Creek (which drains Lemon Glacier) for stream hydrological variables (temperature, pH, conductivity, dissolved oxygen, turbidity, discharge) and associated meteorological variables (precipitation, humidity, temperature). Amidst all the complex fluctuations that follow no immediately apparent pattern, one regular and continuous feature does stand out: a seemingly sinusoidal diurnal variation in pH of about 0.1 that peaks daily at noon. This high-frequency signal is superimposed on a slower signal characterized by multiple-day trends and larger fluctuations in pH. The resulting composite signal with its easily identifiable patterns is an ideal candidate for investigating Fourier signal decomposition. They hypothesize that photosynthesis could be a contributing factor to the diurnal signal and then design and run an experiment modeling bioactive streamwater with a blended chloroplast-rich slurry of fresh spinach leaves (spinach soup). They put a recording pH meter in the spinach soup and expose it to high and low levels of light

  1. Beyond Punnett Squares: Student Word Association and Explanations of Phenotypic Variation through an Integrative Quantitative Genetics Unit Investigating Anthocyanin Inheritance and Expression in Brassica rapa Fast Plants

    Science.gov (United States)

    Smith, Amber R.; Williams, Paul H.; McGee, Seth A.; Dósa, Katalin; Pfammatter, Jesse

    2014-01-01

    Genetics instruction in introductory biology is often confined to Mendelian genetics and avoids the complexities of variation in quantitative traits. Given the driving question “What determines variation in phenotype (Pv)? (Pv=Genotypic variation Gv + environmental variation Ev),” we developed a 4-wk unit for an inquiry-based laboratory course focused on the inheritance and expression of a quantitative trait in varying environments. We utilized Brassica rapa Fast Plants as a model organism to study variation in the phenotype anthocyanin pigment intensity. As an initial curriculum assessment, we used free word association to examine students’ cognitive structures before and after the unit and explanations in students’ final research posters with particular focus on variation (Pv = Gv + Ev). Comparison of pre- and postunit word frequency revealed a shift in words and a pattern of co-occurring concepts indicative of change in cognitive structure, with particular focus on “variation” as a proposed threshold concept and primary goal for students’ explanations. Given review of 53 posters, we found ∼50% of students capable of intermediate to high-level explanations combining both Gv and Ev influence on expression of anthocyanin intensity (Pv). While far from “plug and play,” this conceptually rich, inquiry-based unit holds promise for effective integration of quantitative and Mendelian genetics. PMID:25185225

  2. Beyond Punnett squares: Student word association and explanations of phenotypic variation through an integrative quantitative genetics unit investigating anthocyanin inheritance and expression in Brassica rapa Fast plants.

    Science.gov (United States)

    Batzli, Janet M; Smith, Amber R; Williams, Paul H; McGee, Seth A; Dósa, Katalin; Pfammatter, Jesse

    2014-01-01

    Genetics instruction in introductory biology is often confined to Mendelian genetics and avoids the complexities of variation in quantitative traits. Given the driving question "What determines variation in phenotype (Pv)? (Pv=Genotypic variation Gv + environmental variation Ev)," we developed a 4-wk unit for an inquiry-based laboratory course focused on the inheritance and expression of a quantitative trait in varying environments. We utilized Brassica rapa Fast Plants as a model organism to study variation in the phenotype anthocyanin pigment intensity. As an initial curriculum assessment, we used free word association to examine students' cognitive structures before and after the unit and explanations in students' final research posters with particular focus on variation (Pv = Gv + Ev). Comparison of pre- and postunit word frequency revealed a shift in words and a pattern of co-occurring concepts indicative of change in cognitive structure, with particular focus on "variation" as a proposed threshold concept and primary goal for students' explanations. Given review of 53 posters, we found ∼50% of students capable of intermediate to high-level explanations combining both Gv and Ev influence on expression of anthocyanin intensity (Pv). While far from "plug and play," this conceptually rich, inquiry-based unit holds promise for effective integration of quantitative and Mendelian genetics. © 2014 J. M. Batzli et al. CBE—Life Sciences Education © 2014 The American Society for Cell Biology. This article is distributed by The American Society for Cell Biology under license from the author(s). It is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

  3. Hospital staffing and local pay: an investigation into the impact of local variations in the competitiveness of nurses' pay on the staffing of hospitals in France.

    Science.gov (United States)

    Combes, Jean-Baptiste; Delattre, Eric; Elliott, Bob; Skåtun, Diane

    2015-09-01

    Spatial wage theory suggests that employers in different regions may offer different pay rates to reflect local amenities and cost of living. Higher wages may be required to compensate for a less pleasant environment or a higher cost of living. If wages in a competing sector within an area are less flexible and therefore less competitive this may lead to an inability to employ staff. This paper considers the market for nursing staff in France where there is general regulation of wages and public hospitals compete for staff with the private hospital and non-hospital sectors. We consider two types of nursing staff, registered and assistant nurses and first establish the degree of spatial variation in the competitiveness of pay of nurses in public hospitals. We then consider whether these spatial variations are associated with variation in the employment of nursing staff. We find that despite regulation of pay in the public and private sector, there are substantial local variations in the competitiveness of nurses' pay. We find evidence that the spatial variations in the competitiveness of pay are associated with relative numbers of assistant nurses but not registered nurses. While we find the influence of the competitiveness of pay is small, it suggests that nonpay conditions may be an important factor in adjusting the labour market as might be expected in such a regulated market.

  4. Dead wood dependent organisms in one of the oldest protected forests of Europe: Investigating the contrasting effects of within-stand variation in a highly diversified environment

    Czech Academy of Sciences Publication Activity Database

    Horák, J.; Kout, J.; Vodka, Štěpán; Donato, D. C.

    2016-01-01

    Roč. 363, MAR 1 (2016), s. 229-236 ISSN 0378-1127 Institutional support: RVO:60077344 Keywords : biodiversity * gaps * microenvironment variation Subject RIV: EH - Ecology, Behaviour Impact factor: 3.064, year: 2016 http://www.sciencedirect.com/science/article/pii/S0378112715007744

  5. The Investigation of pH Variation of Water in Spray Tank on Glyphosate and Nicosulfuron Performance on Barnyardgrass and Velvetleaf Control

    Directory of Open Access Journals (Sweden)

    K. Hajmohammadnia Ghalibaf

    2016-03-01

    Full Text Available Introduction: Many factors affect the absorption, transport and performance of herbicides, include; physical factors (such as the orientation, shape, size, cuticle thickness, and its amount downy of the plant leaves, physiological factors (such as the growth stage and its succulence, environmental factors (like rainfall after spraying, relative humidity, wind, and temperature, as well as water quality in spray tank (32. The quality of natural water resources is very important, because the water passes through soil and rocks and dissolve natural salts and transfer them to groundwater reserves (12. pH is a chemical scale for measuring the concentration of hydrogen ions (H+ in the water (21. When pH of solution is less than herbicides pKa (ionic dissociation constant, increasing pH can increase the solubility of herbicides, especially when the absorption limitation of herbicide is because of its solubility (14. To investigate the effect of water pH in herbicide spray tank, testing the effectiveness of weed control is appropriate method. The different species of weeds may have different amounts of ions in the tissue that showed different responses to herbicide solution (14. Accordingly, these basic experiment conducted to study the pH variation of water in spray tank on glyphosate (Roundup® and nicosulfuron (Cruse® performance on barnyardgrass [Echinochloa crus-galli (L. P. Beauv.] and velvetleaf (Abutilon theophrasti Medicus. control in the greenhouse condition. Materials and Methods: Two separate experiments were performed as factorial arrangement of treatments 2×7 based on completely randomized design with six replications at Research Greenhouse of the Ferdowsi University of Mashhad in 2010. Factors included were: pH at 7 levels (4, 5, 6, 7, 8, 9, and 10 obtained by using buffer prepared solutions (+3 control pots for each pH level, and two weeds (barnyardgrass and velvetleaf. Glyphosate and nicosulfuron herbicides were applied post emergent

  6. Inter fraction variations in rectum and bladder volumes and dose distributions during high dose rate brachytherapy treatment of the uterine cervix investigated by repetitive CT-examinations

    International Nuclear Information System (INIS)

    Hellebust, Taran Paulsen; Dale, Einar; Skjoensberg, Ane; Olsen, Dag Rune

    2001-01-01

    Purpose: To evaluate variation of dose to organs at risk for patients receiving fractionated high dose rate gynaecological brachytherapy by using CT-based 3D treatment planning and dose-volume histograms (DVH). Materials and methods: Fourteen patients with cancer of the uterine cervix underwent three to six CT examinations (mean 4.9) during their course of high-dose-rate brachytherapy using radiographically compatible applicators. The rectal and bladder walls were delineated and DVHs were calculated. Results: Inter fraction variation of the bladder volume (CV mean =44.1%) was significantly larger than the inter fraction variation of the mean dose (CV mean =19.9%, P=0.005) and the maximum dose (CV mean =17.5%, P=0.003) of the bladder wall. The same trend was seen for rectum, although the figures were not significantly different. Performing CT examinations at four of seven brachytherapy fractions reduced the uncertainty to 4 and 7% for the bladder and rectal doses, respectively. A linear regression analysis showed a significant, negative relationship between time after treatment start and the whole bladder volume (P=0.018), whereas no correlation was found for the rectum. For both rectum and bladder a linear regression analysis revealed a significant, negative relationship between the whole volume and median dose (P<0.05). Conclusion: Preferably a CT examination should be provided at every fraction. However, this is logistically unfeasible in most institutions. To obtain reliable DVHs the patients will in the future undergo 3-4 CT examinations during the course of brachytherapy at our institution. Since this study showed an association between large bladder volumes and dose reductions, the patients will be treated with a standardized bladder volume

  7. Decadal-scale variation in dune erosion and accretion rates: An investigation of the significance of changing storm tide frequency and magnitude on the Sefton coast, UK

    Science.gov (United States)

    Pye, K.; Blott, S. J.

    2008-12-01

    Monitoring of frontal dune erosion and accretion on the Sefton coast in northwest England over the past 50 years has revealed significant spatial and temporal variations. Previous work has shown that the spatial variations primarily reflect longshore differences in beach and nearshore morphology, energy regime and sediment budget, but the causes of temporal variations have not previously been studied in detail. This paper presents the results of work carried out to test the hypothesis that a major cause of temporal variation is changes in the frequency and magnitude of storms, surges and resulting high tides. Dune toe erosion/accretion records dating from 1958 have been compared with tide gauge records at Liverpool and Heysham. Relatively high dune erosion rates at Formby Point 1958-1968 were associated with a relatively large number of storm tides. Slower erosion at Formby, and relatively rapid accretion in areas to the north and south, occurred during the 1970's and 1980's when there were relatively few major storm tides. After 1990 rates of dune erosion at Formby increased again, and dunes to the north and south experienced slower accretion. During this period high storm tides have been more frequent, and the annual number of hours with water levels above the critical level for dune erosion has increased significantly. An increase in the rate of mean sea-level rise at both Liverpool and Heysham is evident since 1990, but we conclude that this factor is of less importance than the occurrence of extreme high tides and wave action associated with storms. The incidence of extreme high tides shows an identifiable relationship with the lunar nodal tidal cycle, but the evidence indicates that meteorological forcing has also had a significant effect. Storms and surges in the eastern Irish Sea are associated with Atlantic depressions whose direction and rate of movement have a strong influence on wind speeds, wave energy and the height of surge tides. However

  8. An investigation of ionospheric upper transition height variations at low and equatorial latitudes deduced from combined COSMIC and C/NOFS measurements

    Science.gov (United States)

    Yang, Changjun; Zhao, Biqiang; Zhu, Jie; Yue, Xinan; Wan, Weixing

    2017-10-01

    In this study we propose the combination of topside in-situ ion density data from the Communication/Navigation Outage Forecast System (C/NOFS) along with the electron density profile measurement from Constellation Observing System for Meteorology, Ionosphere & Climate (COSMIC) satellites Radio Occultation (RO) for studying the spatial and temporal variations of the ionospheric upper transition height (hT) and the oxygen ion (O+) density scale height. The latitudinal, local time and seasonal distributions of upper transition height show more consistency between hT re-calculated by the profile of the O+ using an α-Chapman function with linearly variable scale height and that determined from direct in-situ ion composition measurements, than with constant scale height and only the COSMIC data. The discrepancy in the values of hT between the C/NOFS measurement and that derived by the combination of COSMIC and C/NOFS satellites observations with variable scale height turns larger as the solar activity decreases, which suggests that the photochemistry and the electrodynamics of the equatorial ionosphere during the extreme solar minimum period produce abnormal structures in the vertical plasma distribution. The diurnal variation of scale heights (Hm) exhibits a minimum after sunrise and a maximum around noon near the geomagnetic equator. Further, the values of Hm exhibit a maximum in the summer hemisphere during daytime, whereas in the winter hemisphere the maximum is during night. Those features of Hm consistently indicate the prominent role of the vertical electromagnetic (E × B) drift in the equatorial ionosphere.

  9. Investigation of correlation of the variations in land subsidence (detected by continuous GPS measurements) and methodological data in the surrounding areas of Lake Urmia

    Science.gov (United States)

    Moghtased-Azar, K.; Mirzaei, A.; Nankali, H. R.; Tavakoli, F.

    2012-11-01

    Lake Urmia, a salt lake in the north-west of Iran, plays a valuable role in the environment, wildlife and economy of Iran and the region, but now faces great challenges for survival. The Lake is in immediate and great danger and is rapidly going to become barren desert. As a result, the increasing demands upon groundwater resources due to expanding metropolitan and agricultural areas are a serious challenge in the surrounding regions of Lake Urmia. The continuous GPS measurements around the lake illustrate significant subsidence rate between 2005 and 2009. The objective of this study was to detect and specify the non-linear correlation of land subsidence and temperature activities in the region from 2005 to 2009. For this purpose, the cross wavelet transform (XWT) was carried out between the two types of time series, namely vertical components of GPS measurements and daily temperature time series. The significant common patterns are illustrated in the high period bands from 180-218 days band (~6-7 months) from September 2007 to February 2009. Consequently, the satellite altimetry data confirmed that the maximum rate of linear trend of water variation in the lake from 2005 to 2009, is associated with time interval from September 2007 to February 2009. This event was detected by XWT as a critical interval to be holding the strong correlation between the land subsidence phenomena and surface temperature. Eventually the analysis can be used for modeling and prediction purposes and probably stave off the damage from subsidence phenomena.

  10. An experimental investigation of the hemodynamic variations due to aplastic vessels within three-dimensional phantom models of the Circle of Willis.

    LENUS (Irish Health Repository)

    Fahy, Paul

    2013-09-10

    A complete circle of Willis (CoW) is found in approximately 30-50% of the population. Anatomical variations, such as absent or surgically clamped vessels, can result in undesirable flow patterns. These can affect the brain\\'s ability to maintain cerebral perfusion and the formation of cerebral aneurysms. An experimental test system was developed to simulate cerebral physiological conditions through three flexible 3D patient-specific models of complete and incomplete CoW geometries. Flow visualizations were performed with isobaric dyes and the mapped dye streamlines were tracked throughout the models. Three to seven flow impact locations were observed for all configurations, corresponding to known sites for aneurysmal formation. Uni and bi-directional cross-flows occurred along the communicating arteries. The greatest shunting of flow occurred for a missing pre-communicating anterior (A1) and posterior (P1) cerebral arteries. The anterior cerebral arteries had the greatest reduction (15-37%) in efferent flow rates for missing either a unilateral A1 or bilateral P1 segments. The bi-directional cross-flows, with multiple afferent flow mixing, observed along the communicating arteries may explain the propensity of aneurysm formation at these sites. Reductions in efferent flow rates due to aplastic vessel configurations may affect normal brain function.

  11. Numerical investigation of heat transfer in a laminar flow in a helical pipe filled with a fluid saturated porous medium: the sensitivity to parameter variations

    International Nuclear Information System (INIS)

    Cheng, L.; Kuznetsov, A.V.

    2005-01-01

    This paper presents the first attempt to investigate numerically heat transfer in a helical pipe filled with a fluid saturated porous medium; the analysis is based on the full momentum equation for porous media that accounts for the Brinkman and Forchheimer extensions of the Darcy law as well as for the flow inertia. Numerical computations are performed in an orthogonal helical coordinate system. The effects of the Darcy number, the Forchheimer coefficient as well as the Dean and Germano numbers on the axial flow velocity, secondary flow, temperature distribution, and the Nusselt number are investigated. (authors)

  12. Numerical investigation of heat transfer in a laminar flow in a helical pipe filled with a fluid saturated porous medium: the sensitivity to parameter variations

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, L.; Kuznetsov, A.V. [North Carolina State Univ., Raleigh, NC (United States). Dept. of Mechanical and Aerospace Engineering

    2005-07-01

    This paper presents the first attempt to investigate numerically heat transfer in a helical pipe filled with a fluid saturated porous medium; the analysis is based on the full momentum equation for porous media that accounts for the Brinkman and Forchheimer extensions of the Darcy law as well as for the flow inertia. Numerical computations are performed in an orthogonal helical coordinate system. The effects of the Darcy number, the Forchheimer coefficient as well as the Dean and Germano numbers on the axial flow velocity, secondary flow, temperature distribution, and the Nusselt number are investigated. (authors)

  13. SU-G-201-13: Investigation of Dose Variation Induced by HDR Ir-192 Source Global Shift Within the Varian Ring Applicator Using Monte Carlo Methods

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Y; Cai, J; Meltsner, S; Chang, Z; Craciunescu, O [Duke University Medical Center, Durham, NC (United States)

    2016-06-15

    Purpose: The Varian tandem and ring applicators are used to deliver HDR Ir-192 brachytherapy for cervical cancer. The source path within the ring is hard to predict due to the larger interior ring lumen. Some studies showed the source could be several millimeters different from planned positions, while other studies demonstrated minimal dosimetric impact. A global shift can be applied to limit the effect of positioning offsets. The purpose of this study was to assess the necessities of implementing a global source shift using Monte Carlo (MC) simulations. Methods: The MCNP5 radiation transport code was used for all MC simulations. To accommodate TG-186 guidelines and eliminate inter-source attenuation, a BrachyVision plan with 10 dwell positions (0.5cm step sizes) was simulated as the summation of 10 individual sources with equal dwell times for simplification. To simplify the study, the tandem was also excluded from the MC model. Global shifts of ±0.1, ±0.3, ±0.5 cm were then simulated as distal and proximal from the reference positions. Dose was scored in water for all MC simulations and was normalized to 100% at the normalization point 0.5 cm from the cap in the ring plane. For dose comparison, Point A was 2 cm caudal from the buildup cap and 2 cm lateral on either side of the ring axis. With seventy simulations, 108 photon histories gave a statistical uncertainties (k=1) <2% for (0.1 cm)3 voxels. Results: Compared to no global shift, average Point A doses were 0.0%, 0.4%, and 2.2% higher for distal global shifts, and 0.4%, 2.8%, and 5.1% higher for proximal global shifts, respectively. The MC Point A doses differed by < 1% when compared to BrachyVision. Conclusion: Dose variations were not substantial for ±0.3 cm global shifts, which is common in clinical practice.

  14. SU-G-201-13: Investigation of Dose Variation Induced by HDR Ir-192 Source Global Shift Within the Varian Ring Applicator Using Monte Carlo Methods

    International Nuclear Information System (INIS)

    Yang, Y; Cai, J; Meltsner, S; Chang, Z; Craciunescu, O

    2016-01-01

    Purpose: The Varian tandem and ring applicators are used to deliver HDR Ir-192 brachytherapy for cervical cancer. The source path within the ring is hard to predict due to the larger interior ring lumen. Some studies showed the source could be several millimeters different from planned positions, while other studies demonstrated minimal dosimetric impact. A global shift can be applied to limit the effect of positioning offsets. The purpose of this study was to assess the necessities of implementing a global source shift using Monte Carlo (MC) simulations. Methods: The MCNP5 radiation transport code was used for all MC simulations. To accommodate TG-186 guidelines and eliminate inter-source attenuation, a BrachyVision plan with 10 dwell positions (0.5cm step sizes) was simulated as the summation of 10 individual sources with equal dwell times for simplification. To simplify the study, the tandem was also excluded from the MC model. Global shifts of ±0.1, ±0.3, ±0.5 cm were then simulated as distal and proximal from the reference positions. Dose was scored in water for all MC simulations and was normalized to 100% at the normalization point 0.5 cm from the cap in the ring plane. For dose comparison, Point A was 2 cm caudal from the buildup cap and 2 cm lateral on either side of the ring axis. With seventy simulations, 108 photon histories gave a statistical uncertainties (k=1) <2% for (0.1 cm)3 voxels. Results: Compared to no global shift, average Point A doses were 0.0%, 0.4%, and 2.2% higher for distal global shifts, and 0.4%, 2.8%, and 5.1% higher for proximal global shifts, respectively. The MC Point A doses differed by < 1% when compared to BrachyVision. Conclusion: Dose variations were not substantial for ±0.3 cm global shifts, which is common in clinical practice.

  15. Investigation of correlation of the variations in land subsidence (detected by continuous GPS measurements and methodological data in the surrounding areas of Lake Urmia

    Directory of Open Access Journals (Sweden)

    K. Moghtased-Azar

    2012-11-01

    Full Text Available Lake Urmia, a salt lake in the north-west of Iran, plays a valuable role in the environment, wildlife and economy of Iran and the region, but now faces great challenges for survival. The Lake is in immediate and great danger and is rapidly going to become barren desert. As a result, the increasing demands upon groundwater resources due to expanding metropolitan and agricultural areas are a serious challenge in the surrounding regions of Lake Urmia. The continuous GPS measurements around the lake illustrate significant subsidence rate between 2005 and 2009. The objective of this study was to detect and specify the non-linear correlation of land subsidence and temperature activities in the region from 2005 to 2009. For this purpose, the cross wavelet transform (XWT was carried out between the two types of time series, namely vertical components of GPS measurements and daily temperature time series. The significant common patterns are illustrated in the high period bands from 180–218 days band (~6–7 months from September 2007 to February 2009. Consequently, the satellite altimetry data confirmed that the maximum rate of linear trend of water variation in the lake from 2005 to 2009, is associated with time interval from September 2007 to February 2009. This event was detected by XWT as a critical interval to be holding the strong correlation between the land subsidence phenomena and surface temperature. Eventually the analysis can be used for modeling and prediction purposes and probably stave off the damage from subsidence phenomena.

  16. Variations of the Functional Brain Network Efficiency in a Young Clinical Sample within the Autism Spectrum: A fNIRS Investigation

    OpenAIRE

    Li, Yanwei; Yu, Dongchuan

    2018-01-01

    Autism is a neurodevelopmental disorder with dimensional behavioral symptoms and various damages in the structural and functional brain. Previous neuroimaging studies focused on exploring the differences of brain development between individuals with and without autism spectrum disorders (ASD). However, few of them have attempted to investigate the individual differences of the brain features among subjects within the Autism spectrum. Our main goal was to explore the individual differences of ...

  17. INVESTIGATING THE fFORMATION OF INTERMETALLIC COMPOUNDS AND THE VARIATION OF BOND STRENGTH BETWEEN Al-Cu LAYERS AFTER ANNEALING IN PRESENCE OF NICKEL BETWEEN LAYERS

    Directory of Open Access Journals (Sweden)

    A. Shabani

    2016-06-01

    Full Text Available In the present study, the effect of post-rolling annealing heat treatment on the formation of intermetallic compounds between Al-Cu strips, in the presence of nickel coating on the Cu strips, was investigated. In addition, the effect of post-rolling annealing and intermetallic compounds on the bond strength of Al-Cu strips was evaluated. In order to prepare samples, Cu strips were coated with nickel by electroplating process. After surface preparing, Cu strips were placed between two Al strips and roll bonded. This method is used for producing Al-Ni-Cu composites. Then the samples were annealed at 773K for 2 h. The formation of intermetallic compounds was studied using energy dispersive spectroscopy (EDS and X-ray diffraction (XRD. Also, in order to investigate bond strength of Al-Cu after post-rolling annealing heat treatment, samples were produced using nickel powder and nickel coating. Then bond strength of strips was investigated using peeling test. The results revealed that by post-rolling annealing of layers, the bond strength between Al-Cu strips decreases dramatically.

  18. Preparation of zinc ferrite nano powders by high energy wet-milling method and investigation of Crystallites size variation during this process

    International Nuclear Information System (INIS)

    Masoudi, H.; Aftabi, A.; Mozafari, M.; Amighian, J.

    2007-01-01

    In this research work ZnFe 2 O 4 nano powders were prepared by high-energy wet-milling process, using metallic Fe and Zn powders. The process was investigated by XRD technique. 10% of the zinc ferrite was formed after 10 h milling. The as-milled sample was annealed at 500, 550 and 600 d egree C . Ultimately a single sample was obtained at 600 d egree C . Using sherrer's formula, the mean crystallite size of the as-milled and annealed powders were calculated. These were in the range of 17.9 to 20.4 nm.

  19. Variational principles

    CERN Document Server

    Moiseiwitsch, B L

    2004-01-01

    This graduate-level text's primary objective is to demonstrate the expression of the equations of the various branches of mathematical physics in the succinct and elegant form of variational principles (and thereby illuminate their interrelationship). Its related intentions are to show how variational principles may be employed to determine the discrete eigenvalues for stationary state problems and to illustrate how to find the values of quantities (such as the phase shifts) that arise in the theory of scattering. Chapter-by-chapter treatment consists of analytical dynamics; optics, wave mecha

  20. Numerical investigation on the variation of welding stresses after material removal from a thick titanium alloy plate joined by electron beam welding

    International Nuclear Information System (INIS)

    Liu, Chuan; Zhang, Jianxun; Wu, Bing; Gong, Shuili

    2012-01-01

    Highlights: → After less materials removal from the top, stresses on the bottom remain unchanged. → The transverse stress within the weld decreases significantly with material removal. → Local material removal does not influence the longitudinal stress significantly. -- Abstract: The stress modification after material removal from a 50 mm thick titanium alloy plate jointed by electron beam welding (EBW) was investigated through the finite element method (FEM). The welding experiment and milling process were carried out to experimentally determine the stresses induced by EBW and their modification after local material removal. The modification of as-welded stresses due to the local material removal method and the whole layer removal method was discussed with the finite element analysis. Investigated results showed that with less materials removal from the top, the stresses on the bottom surface remain almost unchanged; after material removal from the top and bottom part, the transverse stress on the newly-formed surface decreases significantly as compared to the as-welded stresses at the same locations; however, the stress modification only occurs at the material removal region in the case of local region removal method; the longitudinal stress decreases with the whole layer removal method while remains almost unchanged with the local region removal method.

  1. Research of some operating parameters and the emissions level variation in a spark ignited engine through on-board investigation methods in different loading conditions

    Science.gov (United States)

    Iosif, Ferenti; Baldean, Doru Laurean

    2014-06-01

    The present paper shows research made on a spark ignited engine with port fuel injection in different operation conditions in order to improve the comprehension about the cold start sequence, acceleration when changing the gear ratios, quality of combustion process and also any measures to be taken for pollutant reduction in such cases. The engineering endeavor encompasses the pollutants investigation during the operation time of gasoline supplied engine with four inline cylinders in different conditions. The temperature and any other parameters were measured with specific sensors installed on the engine or in the exhaust pipes. All the data collected has been evaluated using electronic investigation systems and highly developed equipment. In this manner it has enabled the outline of the idea of how pollutants of engine vary in different operating conditions. Air quality in the everyday environment is very important for the human health, and thus the ambient air quality has a well-known importance in the European pollution standards and legislation. The high level of attention directed to the pollution problem in the European lifestyle is a driving force for all kinds of studies in the field of the reduction of engine emission.

  2. Investigation of Relative Time Constant Influence of Inertial Part of Superheater on Quality of Steam Temperature Control Behind Boiler in Broad Band of Loading Variations

    Directory of Open Access Journals (Sweden)

    G. T. Kulakov

    2008-01-01

    Full Text Available The paper is devoted to computational investigation of influence relative time constant of an object which changes in broad band on quality of steam temperature control behind a boiler with due account of value of regulating action in the system with PI- and PID- regulator. The simulation has been based on a single-loop automatic control system (ACS. It has been revealed that the less value of the relative time constant of an object leads to more integral control error in system with PID- regulator while operating external ACS perturbation. Decrease of numerical value of relative time constant of an object while operating external perturbation causes decrease of relative time concerning appearance of maximum dynamic control error from common relative control time.

  3. Investigation of heart proteome of different consomic mouse strains. Testing the effect of polymorphisms on the proteome-wide trans-variation of proteins

    Directory of Open Access Journals (Sweden)

    Stefanie Forler

    2015-06-01

    Full Text Available We investigated to which extent polymorphisms of an individual affect the proteomic network. Consomic mouse strains (CS were used to study the trans-effect of the cis-variant (polymorphic proteins of the strain PWD/Ph on the proteins of the host strain C57BL/6J. The cardiac proteome of ten CSs was analyzed by 2-DE and MS. Cis-variant PWD proteins altered a high number of C57BL/6J proteins, but the number of trans-variant proteins differed considerably between different CSs. Cardiac hypertrophy was induced in CSs. We found that high variability of the proteome, as induced by polymorphisms in CS14, acts protective against the complex disease.

  4. Using ecological momentary assessment to investigate short-term variations in sexual functioning in a sample of peri-menopausal women from Iran.

    Directory of Open Access Journals (Sweden)

    Amir H Pakpour

    Full Text Available The investigation of short-term changes in female sexual functioning has received little attention so far. The aims of the study were to gain empirical knowledge on within-subject and within- and across-variable fluctuations in women's sexual functioning over time. More specifically, to investigate the stability of women´s self-reported sexual functioning and the moderating effects of contextual and interpersonal factors. A convenience sample of 206 women, recruited across eight Health care Clinics in Rasht, Iran. Ecological momentary assessment was used to examine fluctuations of sexual functioning over a six week period. A shortened version of the Female Sexual Function Index (FSFI was applied to assess sexual functioning. Self-constructed questions were included to assess relationship satisfaction, partner's sexual performance and stress levels. Mixed linear two-level model analyses revealed a link between orgasm and relationship satisfaction (Beta = 0.125, P = 0.074 with this link varying significantly between women. Analyses further revealed a significant negative association between stress and all six domains of women's sexual functioning. Women not only reported differing levels of stress over the course of the assessment period, but further differed from each other in how much stress they experienced and how much this influenced their sexual response. Orgasm and sexual satisfaction were both significantly associated with all other domains of sexual function (P<0.001. And finally, a link between partner performance and all domains of women`s sexual functioning (P<0.001 could be detected. Except for lubrication (P = 0.717, relationship satisfaction had a significant effect on all domains of the sexual response (P<0.001. Overall, our findings support the new group of criteria introduced in the DSM-5, called "associated features" such as partner factors and relationship factors. Consideration of these criteria is important and necessary for

  5. SU-E-I-22: A Comprehensive Investigation of Noise Variations Between the GE Discovery CT750 HD and GE LightSpeed VCT

    International Nuclear Information System (INIS)

    Bache, S; Loyer, E; Stauduhar, P; Liu, X; Rong, J

    2015-01-01

    Purpose: To quantify and compare the noise properties between two GE CT models-the Discovery CT750 HD (aka HD750) and LightSpeed VCT, with the overall goal of assessing the impact in clinical diagnostic practice. Methods: Daily QC data from a fleet of 9 CT scanners currently in clinical use were investigated – 5 HD750 and 4 VCT (over 600 total acquisitions for each scanner). A standard GE QC phantom was scanned daily using two sets of scan parameters with each scanner over 1 year. Water CT number and standard deviation were recorded from the image of water section of the QC phantom. The standard GE QC scan parameters (Pitch = 0.516, 120kVp, 0.4s, 335mA, Small Body SFOV, 5mm thickness) and an in-house developed protocol (Axial, 120kVp, 1.0s, 240mA, Head SFOV, 5mm thickness) were used, with Standard reconstruction algorithm. Noise was measured as the standard deviation in the center of the water phantom image. Inter-model noise distributions and tube output in mR/mAs were compared to assess any relative differences in noise properties. Results: With the in-house protocols, average noise for the five HD750 scanners was ∼9% higher than the VCT scanners (5.8 vs 5.3). For the GE QC protocol, average noise with the HD750 scanners was ∼11% higher than with the VCT scanners (4.8 vs 4.3). This discrepancy in noise between the two models was found despite the tube output in mR/mAs being comparable with the HD750 scanners only having ∼4% lower output (8.0 vs 8.3 mR/mAs). Conclusion: Using identical scan protocols, average noise in images from the HD750 group was higher than that from the VCT group. This confirms feedback from an institutional radiologist’s feedback regarding grainier patient images from HD750 scanners. Further investigation is warranted to assess the noise texture and distribution, as well as clinical impact

  6. Somato-synaptic variation of GABA(A) receptors in cultured murine cerebellar granule cells: investigation of the role of the alpha6 subunit.

    Science.gov (United States)

    Mellor, J R; Wisden, W; Randall, A D

    2000-07-10

    Electrophysiological investigation of cultured cerebellar murine granule cells revealed differences between the GABA(A) receptors at inhibitory synapses and those on the cell body. Specifically, mIPSCs decayed more rapidly than cell body receptors deactivated, the mean single channel conductance at the synapse (32 pS) was greater than that at cell body (21 pS) and only cell body receptors were sensitive to Zn(2+) (150 microM), which depressed response amplitude by 82+/-5% and almost doubled the rate of channel deactivation. The GABA(A) receptor alpha6 subunit is selectively expressed in cerebellar granule cells. Although concentrated at synapses, it is also found on extrasynaptic membranes. Using a mouse line (Deltaalpha6lacZ) lacking this subunit, we investigated its role in the somato-synaptic differences in GABA(A) receptor function. All differences between cell body and synaptic GABA(A) receptors observed in wild-type (WT) granule cells persisted in Deltaalpha6lacZ cells, thus demonstrating that they are not specifically due to the cellular distribution of the alpha6 subunit. However, mIPSCs from WT and Deltaalpha6lacZ cells differed in both their kinetics (faster decay in WT cells) and underlying single channel conductance (32 pS WT, 25 pS Deltaalpha6lacZ). This provides good evidence for a functional contribution of the alpha6 subunit to postsynaptic GABA(A) receptors in these cells. Despite this, deactivation kinetics of mIPSCs in WT and Deltaalpha6lacZ granule cells exhibited similar benzodiazepene (BDZ) sensitivity. This suggests that the enhanced BDZ-induced ataxia seen in Deltaalpha6lacZ mice may reflect physiological activity at extrasynaptic receptors which, unlike those at synapses, display differential BDZ-sensitivity in WT and Deltaalpha6lacZ granule cells (Jones, A.M., Korpi, E.R., McKernan, R.M., Nusser, Z., Pelz, R., Makela, R., Mellor, J.R., Pollard, S., Bahn, S., Stephenson, F.A., Randall, A.D., Sieghart, W., Somogyi, P., Smith, A.J.H., Wisden

  7. Investigation on the variation of channel resistance and contact resistance of SiZnSnO semiconductor depending on Si contents using transmission line method

    Science.gov (United States)

    Lee, Byeong Hyeon; Han, Sangmin; Lee, Sang Yeol

    2018-01-01

    Amorphous silicon-zinc-tin-oxide (a-SZTO) thin film transistors (TFTs) have been fabricated depending on the silicon ratio in channel layers. The a-SZTO TFT exhibited high electrical properties, such as high mobility of 23 cm2 V-1 s-1, subthreshold swing of 0.74 V/decade and ION/OFF of 2.8 × 108, despite of the addition of Si suppressor. The physical mechanism on the change of the sheet resistance and the contact resistance in a-SZTO TFT has been investigated and proposed closely related with the Si ratio. Both resistances were increased as increasing Si ratio, which clearly indicated that the role of Si is a carrier suppressor directly leading to the increase of channel and contact resistances. To explain the role of Si as a carrier suppressor, the conduction band offset mechanism has been also proposed depending on the change of carrier concentration in channel layer and at the interface between electrode and channel layer. 2007.01-2011.12 Senior Researcher at korea institute of science and technology (KOREA). 2008.01-2011.12 Professor at University of Science and Technology (KOREA). 1995.01-2007.12 Professor at Yonsei University (KOREA). 2002.01-2003.12 Inviting Researcher at Los Alamos National Lab (USA). 1993.01-1995.12 Senior Researcher at Electronics and Telecommunications Research Institute (KOREA). 1992.01-1993.01 Research Associate at State University of New York at Buffalo (USA).

  8. Variations of the Functional Brain Network Efficiency in a Young Clinical Sample within the Autism Spectrum: A fNIRS Investigation

    Directory of Open Access Journals (Sweden)

    Yanwei Li

    2018-02-01

    Full Text Available Autism is a neurodevelopmental disorder with dimensional behavioral symptoms and various damages in the structural and functional brain. Previous neuroimaging studies focused on exploring the differences of brain development between individuals with and without autism spectrum disorders (ASD. However, few of them have attempted to investigate the individual differences of the brain features among subjects within the Autism spectrum. Our main goal was to explore the individual differences of neurodevelopment in young children with Autism by testing for the association between the functional network efficiency and levels of autistic behaviors, as well as the association between the functional network efficiency and age. Forty-six children with Autism (ages 2.0–8.9 years old participated in the current study, with levels of autistic behaviors evaluated by their parents. The network efficiency (global and local network efficiency were obtained from the functional networks based on the oxy-, deoxy-, and total-Hemoglobin series, respectively. Results indicated that the network efficiency decreased with age in young children with Autism in the deoxy- and total-Hemoglobin-based-networks, and children with a relatively higher level of autistic behaviors showed decreased network efficiency in the oxy-hemoglobin-based network. Results suggest individual differences of brain development in young children within the Autism spectrum, providing new insights into the psychopathology of ASD.

  9. An electrochemical investigation of TMJ implant metal alloys in an artificial joint fluid environment: the influence of pH variation.

    Science.gov (United States)

    Royhman, Dmitry; Radhakrishnan, Rashmi; Yuan, Judy Chia-Chun; Mathew, Mathew T; Mercuri, Louis G; Sukotjo, Cortino

    2014-10-01

    To investigate the corrosion behaviour of commonly used TMJ implants alloys (CoCrMo and Ti6Al4V) under simulated physiological conditions. Corrosion behaviour was evaluated using standard electrochemical corrosion techniques and galvanic corrosion techniques as per ASTM standards. Standard electrochemical tests (E(corr), I(corr), R(p) and C(f)) were conducted in bovine calf serum (BCS), as a function of alloys type and different pHs. Galvanic corrosion tests were conducted in BCS at a pH of 7.6. Alloy surfaces were characterized using white-light interferometry (WLI) and scanning electron microscopy (SEM). The potentiodynamic test results exhibited the enhanced passive layer growth and a better corrosion resistance of Ti6Al4V compared to CoCrMo. Electrochemical impedance spectroscopy measurements demonstrated the influence of protein as a function of pH on corrosion mechanisms/kinetics. Galvanic coupling was not a major contributor to corrosion. SEM and WLI images demonstrated a significantly higher in surface roughness in CoCrMo after corrosion. The results of this study suggest that Ti6Al4V shows superior corrosion behaviour to CoCrMo due to its strong passive layer, simulated joint fluid components can affect the electrochemical nature of the metal/electrolyte interface as a function of pH, and the galvanic effect of coupling CoCrMo and Ti6Al4V in a single joint is weak. Published by Elsevier Ltd.

  10. The association between Mediterranean Diet Score and glucokinase regulatory protein gene variation on the markers of cardiometabolic risk: an analysis in the European Prospective Investigation into Cancer (EPIC)-Norfolk study.

    Science.gov (United States)

    Sotos-Prieto, Mercedes; Luben, Robert; Khaw, Kay-Tee; Wareham, Nicholas J; Forouhi, Nita G

    2014-07-14

    Consumption of a Mediterranean diet (MD) and genetic variation in the glucokinase regulatory protein (GCKR) gene have been reported to be associated with TAG and glucose metabolism. It is uncertain whether there is any interaction between these factors. Therefore, the aims of the present study were to test the association of adherence to a MD and rs780094 (G>A) SNP in the GCKR gene with the markers of cardiometabolic risk, and to investigate the interaction between genetic variation and MD adherence. We studied 20 986 individuals from the European Prospective Investigation into Cancer (EPIC)-Norfolk study. The relative Mediterranean Diet Score (rMED: range 0-18) was used to assess MD adherence. Linear regression was used to estimate the association between the rMED, genotype and cardiometabolic continuous traits, adjusting for potential confounders. In adjusted analyses, we observed independent associations of MD adherence and genotype with cardiometabolic risk, with the highest risk group (AA genotype; lowest rMED) having higher concentrations of TAG, total cholesterol and apoB (12·5, 2·3 and 3·1%, respectively) v. those at the lowest risk (GG genotype; highest rMED). However, the associations of MD adherence with metabolic markers did not differ by genotype, with no significant gene-diet interactions for lipids or for glycated Hb. In conclusion, we found independent associations of the rMED and of the GCKR genotype with cardiometabolic profile, but found no evidence of interaction between them.

  11. Using a 2D Model of the Io Plasma Torus to Investigate the Effects of Density Variations on the Morphology and Intensity of the Io Footprint

    Science.gov (United States)

    Payan, A. P.; Rajendar, A.; Paty, C. S.; Bonfond, B.; Crary, F.

    2012-12-01

    Alfvén waves are capable of accelerating charged particles along magnetic field lines, we assume that the discrete Io footprint features are created at these longitudes, and that the intensity of each of these features is positively correlated to the energy transported by the wave front as it exits the plasma torus. Therefore, the model allows us to investigate both the effects of density changes and of Io's position in the plasma torus on the intensity and the morphology of the Io footprint. In this context, the model enables us to determine the density increase in the plasma torus required to explain the apparent disappearance of Io footprint given its position at that time.

  12. Metaleptic Variations

    OpenAIRE

    Pernot, Dominique

    2014-01-01

    Les derniers romans de Gabriel Josipovici offrent beaucoup de variété, allant de la parodie, de la fiction comique légère, dans Only Joking et Making Mistakes, à des sujets plus graves, plus personnels, ontologiques. Dans un court roman, Everything Passes, et dans un roman majeur, Goldberg: Variations, le lecteur est amené à se poser des questions sur la nature mystérieuse de la réalité, qui est, trop souvent, acceptée sans conteste par de nombreux roma...

  13. Experiencing variation

    DEFF Research Database (Denmark)

    Kobayashi, Sofie; Berge, Maria; Grout, Brian William Wilson

    2017-01-01

    This study contributes towards a better understanding of learning dynamics in doctoral supervision by analysing how learning opportunities are created in the interaction between supervisors and PhD students, using the notion of experiencing variation as a key to learning. Empirically, we have based...... the study on four video-recorded sessions, with four different PhD students and their supervisors, all from life sciences. Our analysis revealed that learning opportunities in the supervision sessions concerned either the content matter of research (for instance, understanding soil structure......), or the research methods— more specifically how to produce valid results. Our results illustrate how supervisors and PhD students create a space of learning together in their particular discipline by varying critical aspects of their research in their discussions. Situations where more openended research issues...

  14. Genetic variation in California oaks

    Science.gov (United States)

    Constance I. Millar; Diane L. Delany; Lawrence A. Riggs

    1990-01-01

    In forestry the importance of genetic variation for successful reproduction, survival and growth has been widely documented for commercial conifers; until recently, little genetic work has been done on the California oaks. Even before the nature of genetic variation was scientifically investigated, its importance was suspected in operational forestry. Many failures of...

  15. SU-F-J-55: Feasibility of Supraclavicular Field Treatment by Investigating Variation of Junction Position Between Breast Tangential and Supraclavicular Fields for Deep Inspiration Breath Hold (DIBH) Left Breast Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, H; Sarkar, V; Paxton, A; Rassiah-Szegedi, P; Huang, Y; Szegedi, M; Huang, L; Su, F; Salter, B [University Utah, Salt Lake City, UT (United States)

    2016-06-15

    Purpose: To explore the feasibility of supraclavicular field treatment by investigating the variation of junction position between tangential and supraclavicular fields during left breast radiation using DIBH technique. Methods: Six patients with left breast cancer treated using DIBH technique were included in this study. AlignRT system was used to track patient’s breast surface. During daily treatment, when the patient’s DIBH reached preset AlignRT tolerance of ±3mm for all principle directions (vertical, longitudinal, and lateral), the remaining longitudinal offset was recorded. The average with standard-deviation and the range of daily longitudinal offset for the entire treatment course were calculated for all six patients (93 fractions totally). The ranges of average ± 1σ and 2σ were calculated, and they represent longitudinal field edge error with the confidence level of 68% and 95%. Based on these longitudinal errors, dose at junction between breast tangential and supraclavicular fields with variable gap/overlap sizes was calculated as a percentage of prescription (on a representative patient treatment plan). Results: The average of longitudinal offset for all patients is 0.16±1.32mm, and the range of longitudinal offset is −2.6 to 2.6mm. The range of longitudinal field edge error at 68% confidence level is −1.48 to 1.16mm, and at 95% confidence level is −2.80 to 2.48mm. With a 5mm and 1mm gap, the junction dose could be as low as 37.5% and 84.9% of prescription dose; with a 5mm and 1mm overlap, the junction dose could be as high as 169.3% and 117.6%. Conclusion: We observed longitudinal field edge error at 95% confidence level is about ±2.5mm, and the junction dose could reach 70% hot/cold between different DIBH. However, over the entire course of treatment, the average junction variation for all patients is within 0.2mm. The results from our study shows it is potentially feasible to treat supraclavicular field with breast tangents.

  16. The nonholonomic variational principle

    Energy Technology Data Exchange (ETDEWEB)

    Krupkova, Olga [Department of Algebra and Geometry, Faculty of Science, Palacky University, Tomkova 40, 779 00 Olomouc (Czech Republic); Department of Mathematics, La Trobe University, Bundoora, Victoria 3086 (Australia)], E-mail: krupkova@inf.upol.cz

    2009-05-08

    A variational principle for mechanical systems and fields subject to nonholonomic constraints is found, providing Chetaev-reduced equations as equations for extremals. Investigating nonholonomic variations of the Chetaev type and their properties, we develop foundations of the calculus of variations on constraint manifolds, modelled as fibred submanifolds in jet bundles. This setting is appropriate to study general first-order 'nonlinear nonitegrable constraints' that locally are given by a system of first-order ordinary or partial differential equations. We obtain an invariant constrained first variation formula and constrained Euler-Lagrange equations both in intrinsic and coordinate forms, and show that the equations are the same as Chetaev equations 'without Lagrange multipliers', introduced recently by other methods. We pay attention to two possible settings: first, when the constrained system arises from an unconstrained Lagrangian system defined in a neighbourhood of the constraint, and second, more generally, when an 'internal' constrained system on the constraint manifold is given. In the latter case a corresponding unconstrained system need not be a Lagrangian, nor even exist. We also study in detail an important particular case: nonholonomic constraints that can be alternatively modelled by means of (co)distributions in the total space of the fibred manifold; in nonholonomic mechanics this happens whenever constraints affine in velocities are considered. It becomes clear that (and why) if the distribution is completely integrable (= the constraints are semiholonomic), the principle of virtual displacements holds and can be used to obtain the constrained first variational formula by a more or less standard procedure, traditionally used when unconstrained or holonomic systems are concerned. If, however, the constraint is nonintegrable, no significant simplifications are available. Among others, some properties of nonholonomic

  17. Diurnal variations of Titan

    Science.gov (United States)

    Cui, J.; Galand, M.; Yelle, R. V.; Vuitton, V.; Wahlund, J.-E.; Lavvas, P. P.; Mueller-Wodarg, I. C. F.; Kasprzak, W. T.; Waite, J. H.

    2009-04-01

    We present our analysis of the diurnal variations of Titan's ionosphere (between 1,000 and 1,400 km) based on a sample of Ion Neutral Mass Spectrometer (INMS) measurements in the Open Source Ion (OSI) mode obtained from 8 close encounters of the Cassini spacecraft with Titan. Though there is an overall ion depletion well beyond the terminator, the ion content on Titan's nightside is still appreciable, with a density plateau of ~700 cm-3 below ~1,300 km. Such a plateau is associated with the combination of distinct diurnal variations of light and heavy ions. Light ions (e.g. CH5+, HCNH+, C2H5+) show strong diurnal variation, with clear bite-outs in their nightside distributions. In contrast, heavy ions (e.g. c-C3H3+, C2H3CNH+, C6H7+) present modest diurnal variation, with significant densities observed on the nightside. We propose that the distinctions between light and heavy ions are associated with their different chemical loss pathways, with the former primarily through "fast" ion-neutral chemistry and the latter through "slow" electron dissociative recombination. The INMS data suggest day-to-night transport as an important source of ions on Titan's nightside, to be distinguished from the conventional scenario of auroral ionization by magnetospheric particles as the only ionizing source on the nightside. This is supported by the strong correlation between the observed night-to-day ion density ratios and the associated ion lifetimes. We construct a time-dependent ion chemistry model to investigate the effects of day-to-night transport on the ionospheric structures of Titan. The predicted diurnal variation has similar general characteristics to those observed, with some apparent discrepancies which could be reconciled by imposing fast horizontal thermal winds in Titan's upper atmosphere.

  18. The relative contribution of provider and ED-level factors to variation among the top 15 reasons for ED admission.

    Science.gov (United States)

    Khojah, Imad; Li, Suhui; Luo, Qian; Davis, Griffin; Galarraga, Jessica E; Granovsky, Michael; Litvak, Ori; Davis, Samuel; Shesser, Robert; Pines, Jesse M

    2017-09-01

    We examine adult emergency department (ED) admission rates for the top 15 most frequently admitted conditions, and assess the relative contribution in admission rate variation attributable to the provider and hospital. This was a retrospective, cross-sectional study of ED encounters (≥18years) from 19 EDs and 603 providers (January 2012-December 2013), linked to the Area Health Resources File for county-level information on healthcare resources. "Hospital admission" was the outcome, a composite of inpatient, observation, or intra-hospital transfer. We studied the 15 most commonly admitted conditions, and calculated condition-specific risk-standardized hospital admission rates (RSARs) using multi-level hierarchical generalized linear models. We then decomposed the relative contribution of provider-level and hospital-level variation for each condition. The top 15 conditions made up 34% of encounters and 49% of admissions. After adjustment, the eight conditions with the highest hospital-level variation were: 1) injuries, 2) extremity fracture (except hip fracture), 3) skin infection, 4) lower respiratory disease, 5) asthma/chronic obstructive pulmonary disease (A&C), 6) abdominal pain, 7) fluid/electrolyte disorders, and 8) chest pain. Hospital-level intra-class correlation coefficients (ICC) ranged from 0.042 for A&C to 0.167 for extremity fractures. Provider-level ICCs ranged from 0.026 for abdominal pain to 0.104 for chest pain. Several patient, hospital, and community factors were associated with admission rates, but these varied across conditions. For different conditions, there were different contributions to variation at the hospital- and provider-level. These findings deserve consideration when designing interventions to optimize admission decisions and in value-based payment programs. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Exploring language variation across Europe

    DEFF Research Database (Denmark)

    Hovy, Dirk; Johannsen, Anders Trærup

    2016-01-01

    Language varies not only between countries, but also along regional and sociodemographic lines. This variation is one of the driving factors behind language change. However, investigating language variation is a complex undertaking: the more factors we want to consider, the more data we need. Tra...... use of large amounts of data and provides statistical analyses, maps, and interactive features that enable scholars to explore language variation in a data-driven way.......Language varies not only between countries, but also along regional and sociodemographic lines. This variation is one of the driving factors behind language change. However, investigating language variation is a complex undertaking: the more factors we want to consider, the more data we need...... training in both variational linguistics and computational methods, a combination that is still not common. We take a first step here to alleviate the problem by providing an interface to explore large-scale language variation along several socio-demographic factors without programming knowledge. It makes...

  20. Variational and quasi-variational inequalities in mechanics

    CERN Document Server

    Kravchuk, Alexander S

    2007-01-01

    The essential aim of the present book is to consider a wide set of problems arising in the mathematical modelling of mechanical systems under unilateral constraints. In these investigations elastic and non-elastic deformations, friction and adhesion phenomena are taken into account. All the necessary mathematical tools are given: local boundary value problem formulations, construction of variational equations and inequalities, and the transition to minimization problems, existence and uniqueness theorems, and variational transformations (Friedrichs and Young-Fenchel-Moreau) to dual and saddle-point search problems. Important new results concern contact problems with friction. The Coulomb friction law and some others are considered, in which relative sliding velocities appear. The corresponding quasi-variational inequality is constructed, as well as the appropriate iterative method for its solution. Outlines of the variational approach to non-stationary and dissipative systems and to the construction of the go...

  1. Variational principles for locally variational forms

    International Nuclear Information System (INIS)

    Brajercik, J.; Krupka, D.

    2005-01-01

    We present the theory of higher order local variational principles in fibered manifolds, in which the fundamental global concept is a locally variational dynamical form. Any two Lepage forms, defining a local variational principle for this form, differ on intersection of their domains, by a variationally trivial form. In this sense, but in a different geometric setting, the local variational principles satisfy analogous properties as the variational functionals of the Chern-Simons type. The resulting theory of extremals and symmetries extends the first order theories of the Lagrange-Souriau form, presented by Grigore and Popp, and closed equivalents of the first order Euler-Lagrange forms of Hakova and Krupkova. Conceptually, our approach differs from Prieto, who uses the Poincare-Cartan forms, which do not have higher order global analogues

  2. Diural TSH variations in hypothyroidism.

    Science.gov (United States)

    Weeke, J; Laurberg, P

    1976-07-01

    There is a circadian variation in serum TSH in euthyroid subjects. A similar diurnal variation has been demonstrated in patients with hypothyroidism. In the present study the 24-hour pattern of serum TSH was investigated in eight patients with hypothyroidism of varying severity and in five hypothyroid patients treated with thyroxine (T4). There was a circadian variation in serum TSH in patients with hypothyroidism of moderate degree, and in patients treated for severe hypothyrodism with thyroxine. The pattern was similar to that found in normal subjects, i.e., low TSH levels in the daytime and higher levels at night. In severely hypothyroid patients, no diurnal variation in serum TSH was observed. A practical consequence is that blood samples for TSH measurements in patients with moderately elevated TSH levels are best taken after 1100 h, when the low day levels are reached.

  3. Variation and Mathematics Pedagogy

    Science.gov (United States)

    Leung, Allen

    2012-01-01

    This discussion paper put forwards variation as a theme to structure mathematical experience and mathematics pedagogy. Patterns of variation from Marton's Theory of Variation are understood and developed as types of variation interaction that enhance mathematical understanding. An idea of a discernment unit comprising mutually supporting variation…

  4. Calculus of variations

    CERN Document Server

    Elsgolc, L E; Stark, M

    1961-01-01

    Calculus of Variations aims to provide an understanding of the basic notions and standard methods of the calculus of variations, including the direct methods of solution of the variational problems. The wide variety of applications of variational methods to different fields of mechanics and technology has made it essential for engineers to learn the fundamentals of the calculus of variations. The book begins with a discussion of the method of variation in problems with fixed boundaries. Subsequent chapters cover variational problems with movable boundaries and some other problems; sufficiency

  5. Vascular Variations Associated with Intracranial Aneurysms.

    Science.gov (United States)

    Orakdogen, Metin; Emon, Selin Tural; Somay, Hakan; Engin, Taner; Is, Merih; Hakan, Tayfun

    2017-01-01

    To investigate the vascular variations in patients with intracranial aneurysm in circle of Willis. We used the data on 128 consecutive intracranial aneurysm cases. Cerebral angiography images were analyzed retrospectively. Arteries were grouped as anterior cerebral arterial system (ACS), posterior cerebral arterial system (PCS) and middle cerebral arterial system (MCS) for grouping vascular variations. Lateralization, being single/multiple, gender; and also any connection with accompanying aneurysms" number, localization, dimension, whether bleeding/incidental aneurysm has been inspected. Variations were demonstrated in 57.8% of the cases. The most common variation was A1 variation (34.4%). The rate of variations was 36.7%, 24.2% and 10.2% respectively in ACS, PCS and MCS. MCS variations were significantly higher in males. Anterior communicating artery (ACoA) aneurysm observance rates were significantly higher and posterior communicating artery (PCoA) aneurysm and middle cerebral artery (MCA) aneurysm observance rates were significantly lower when compared to "no ACS variation detected" cases. In "PCS variation detected" cases, PCoA aneurysm observance rates and coexistence of multiple variations were significantly higher. The rate of vascular variations in patients with aneurysms was 57.8%. Arterial hypoplasia and aplasia were the most common variations. ACS was the most common region that variations were located in; they were mostly detected on the right side. Coexistence of ACoA aneurysm was higher than PCoA and MCA aneurysms. In the PCS variations group, PCoA aneurysms were the most common aneurysms that accompanying the variation and multiple variations were more common than in the other two groups. The variations in MCS were most common in males.

  6. A numerical investigation of the sCO2 recompression cycle off-design behaviour, coupled to a sodium cooled fast reactor, for seasonal variation in the heat sink temperature

    International Nuclear Information System (INIS)

    Floyd, J.; Alpy, N.; Moisseytsev, A.; Haubensack, D.; Rodriguez, G.; Sienicki, J.; Avakian, G.

    2013-01-01

    Highlights: • Year-round behaviour of the supercritical CO 2 recompression cycle is simulated. • Behaviour of the system was uncertain due to large changes in the fluid properties. • Cycle thermodynamic optimisation and component preliminary designs were performed. • No off design cycle stability issues, compressors operate away from surge region. • Independent speed control of compressors maintains power and cycle efficiency. -- Abstract: Supercritical CO 2 cycles are particularly attractive for Generation IV Sodium-Cooled Fast Reactors (SFRs) as they can be simple and compact, but still offer steam-cycle equivalent efficiency while also removing potential for Na/H 2 O reactions. However, CO 2 thermophysical properties are very sensitive close to the critical point which raises, in particular, questions about the compressor and so cycle off-design behaviour when subject to inevitable temperature increases that result from seasonal variations in the heat sink temperature. This publication reports the numerical investigation of such an issue that has been performed using the Plant Dynamics Code (ANL, USA), the cycle being optimised for the next French SFR, ASTRID (1500 MW th ), as a test-case. On design, the net plant efficiency is 42.2% for a high pressure (25 MPa) turbine with an inlet temperature of 515 °C and considering a cycle low temperature of 35 °C. The off-design cycle behaviour is studied based on preliminary designs for the main components and assuming the use of a fixed heat sink flow rate. First results obtained using a common fixed shaft speed for all turbomachines, without any other active control, show no stability issues and roughly constant density (and volumetric flow rate) at the main compressor inlet for the range of heat sink temperature considered (21–40 °C). This occurs because the new stationary states are found without requiring a significant shift of mass to the higher pressure level, meaning the compressor inlet pressure

  7. Calculus of variations

    CERN Document Server

    Elsgolc, Lev D

    2007-01-01

    This concise text offers both professionals and students an introduction to the fundamentals and standard methods of the calculus of variations. In addition to surveys of problems with fixed and movable boundaries, it explores highly practical direct methods for the solution of variational problems.Topics include the method of variation in problems with fixed boundaries; variational problems with movable boundaries and other problems; sufficiency conditions for an extremum; variational problems of constrained extrema; and direct methods of solving variational problems. Each chapter features nu

  8. Biological variation of cystatin C

    DEFF Research Database (Denmark)

    Reinhard, Mark; Erlandsen, Erland; Randers, Else

    2009-01-01

    Introduction: Cystatin C has been investigated as a marker of the glomerular filtration rate. However, previous studies have reported conflicting results concerning the biological variation of cystatin C. The aim of the present study was to evaluate the biological variation of cystatin C...... in comparison to creatinine. Methods: Eight weekly morning blood samples were taken from twenty healthy volunteers (13 females, 7 males) aged 25-61 years. Mean creatinine clearance was 99.7 ml/min/1.73 m2 (range 61.8-139.5) and mean body mass index 23.9 kg/m2 (range 20.3-28.7). A total of 155 samples were...

  9. Quantum Variational Calculus

    OpenAIRE

    Malinowska , Agnieszka B.; Torres , Delfim

    2014-01-01

    International audience; Introduces readers to the treatment of the calculus of variations with q-differences and Hahn difference operators Provides the reader with the first extended treatment of quantum variational calculus Shows how the techniques described can be applied to economic models as well as other mathematical systems This Brief puts together two subjects, quantum and variational calculi by considering variational problems involving Hahn quantum operators. The main advantage of it...

  10. Bilateral renal artery variation

    OpenAIRE

    Üçerler, Hülya; Üzüm, Yusuf; İkiz, Z. Aslı Aktan

    2014-01-01

    Each kidney is supplied by a single renal artery, although renal artery variations are common. Variations of the renal arteryhave become important with the increasing number of renal transplantations. Numerous studies describe variations in renalartery anatomy. Especially the left renal artery is among the most critical arterial variations, because it is the referred side forresecting the donor kidney. During routine dissection in a formalin fixed male cadaver, we have found a bilateral renal...

  11. Genetics and variation

    Science.gov (United States)

    John R. Jones; Norbert V. DeByle

    1985-01-01

    The broad genotypic variability in quaking aspen (Populus tremuloides Michx.), that results in equally broad phenotypic variability among clones is important to the ecology and management of this species. This chapter considers principles of aspen genetics and variation, variation in aspen over its range, and local variation among clones. For a more...

  12. Studying Variation in Tunes

    NARCIS (Netherlands)

    Janssen, B.; van Kranenburg, P.

    2014-01-01

    Variation in music can be caused by different phenomena: conscious, creative manipulation of musical ideas; but also unconscious variation during music recall. It is the latter phenomenon that we wish to study: variation which occurs in oral transmission, in which a melody is taught without the help

  13. Investigation of spectral distribution and variation of irradiance with the passage time of CSI lamps which constitute a solar simulator; Solar simulator ni shiyosuru CSI lamp no supekutoru bunpu, hosha shodo no keiji henka ni kansuru chosa

    Energy Technology Data Exchange (ETDEWEB)

    Sugiyama, T; Yamada, T; Noguchi, T [Japan Quality Assurance Organization, Tokyo (Japan)

    1997-11-25

    Study was made on time-variation of the performance of CSI lamps for solar simulators. In order to accurately evaluate the standard heat collection performance of solar systems in a room, MITI installed an artificial solar light source in the Solar Techno-Center of Japan Quality Assurance Organization for trial use and evaluation. CSI lamp is superior in durability, and can simulate the solar light in the daytime. The light source is composed of 72 metal halide lamps of 1kW arranged in a plane of 3.5times3.5m. The study result on time-variation of a spectral distribution and irradiance by intermittent switching of lamps showed a sufficient durability of 2000h. To ensure the accuracy of a solar heat collector measurement system enough, periodic calibration is being carried out using reference goods. To ensure the reliability and stability for a switching system, periodic maintenance of a power source, stabilizer and electric system is also being carried out in addition to CSI lamps. The stable irradiance and accuracy are being kept by such maintenance and periodic exchange of lamps. 6 figs., 4 tabs.

  14. Polarizer reflectivity variations

    International Nuclear Information System (INIS)

    Ozarski, R.G.; Prior, J.

    1980-01-01

    On Shiva the beam energy along the chain is monitored using available reflections and/or transmission through beam steering, splitting, and polarizing optics without the intrusion of any additional glass for diagnostics. On the preamp table the diagnostic signal is obtained from the signal transmitted through turning mirrors. At the input of each chain the signal is obtained from the transmission through one of the mirrors used for the chain input alignment sensor (CHIP). At the chain output the transmission through the final turning mirror is used. These diagnostics have proved stable and reliable. However, one of the prime diagnostic locations is at the output of the beta rod. The energy at this location is measured by collecting small reflections from the last polarizer surface of the beta Pockels cell polarizer package. Unfortunately, calibration of this diagnostic has varied randomly, seldom remaining stable for a week or more. The cause of this fluctuation has been investigated for the past year and'it has been discovered that polarizer reflectivity varies with humidity. This report will deal with the possible causes that were investigated, the evidence that humidity is causing the variation, and the associated mechanism

  15. Exploring Duopoly Markets with Conjectural Variations

    Science.gov (United States)

    Julien, Ludovic A.; Musy, Olivier; Saïdi, Aurélien W.

    2014-01-01

    In this article, the authors investigate competitive firm behaviors in a two-firm environment assuming linear cost and demand functions. By introducing conjectural variations, they capture the different market structures as specific configurations of a more general model. Conjectural variations are based on the assumption that each firm believes…

  16. Variational Dropout and the Local Reparameterization Trick

    NARCIS (Netherlands)

    Kingma, D.P.; Salimans, T.; Welling, M.; Cortes, C.; Lawrence, N.D.; Lee, D.D.; Sugiyama, M.; Garnett, R.

    2015-01-01

    We investigate a local reparameterizaton technique for greatly reducing the variance of stochastic gradients for variational Bayesian inference (SGVB) of a posterior over model parameters, while retaining parallelizability. This local reparameterization translates uncertainty about global parameters

  17. Solutions to variational inequalities of parabolic type

    Science.gov (United States)

    Zhu, Yuanguo

    2006-09-01

    The existence of strong solutions to a kind of variational inequality of parabolic type is investigated by the theory of semigroups of linear operators. As an application, an abstract semi permeable media problem is studied.

  18. Investigation of neutronic and safety parameters variation in 5 MW research reactor due to U{sub 3}O{sub 8}Al fuel conversion to ThO{sub 2} + U{sub 3}O{sub 8}Al

    Energy Technology Data Exchange (ETDEWEB)

    Gholamzadeh, Zohreh; Alipoor, Zahra; Mirvakili, Seyed Mohammad [Nuclear Science and Technology Research Institute, Tehran (Iran, Islamic Republic of). Reactor Research School; Feghhi, Seyed Amir Hossein [Shahid Beheshti Univ., Tehran (Iran, Islamic Republic of). Dept. of Radiation Application; Vahedi, M.; Bagheri, H. [Univ. of Science and Technology, Tehran (Iran, Islamic Republic of). Energy Dept.; Tenreiro, Claudio [Talca Univ. (Chile). Energy Dept.

    2017-05-15

    Thorium-based fuels could comprise several advantages and are being investigated as a potentially competitive option with uranium-based fuels for research or power reactors. The present study investigates computationally the application of two different thorium-based fuels in a research reactor. Void and temperature reactivity coefficients, safety factor, power peaking factor, neutron generation time, effective delayed neutron fraction and {sup 135}Xe worth parameter were investigated for the fuel conversions. The results showed both the investigated fuels would not significantly disturb neutronic and safety parameters of the modeled core in comparison with its routine fuel loading. However, 235-enriched thorium based fuel concluded in noticeably reduction of High Level Waste (HLW) but 233-enriched type could be taken in attention because of its longer fuel cycle (∝15 %) and integrated neutron flux (∝23 %).

  19. Investigation on the variation of annual ring thicknesses and word densities in South African Pinus radiata stands under the influence of climate and different thinning measures by means of radiodensitometry

    International Nuclear Information System (INIS)

    Bues, C.T.

    1984-01-01

    The present work investigates three phenomena of growth biology in Pinus radiata stands: In the first investigation project: the thickness of the annual rings in relation to climate factors; In the second project: the variability of annual ring thickness and wood density as a function of different thinning measures; In the third project the variability of wood density within a Pinus radiate stand is analyzed. To determine the thickness of the annual rings and the wood density values within the annual rings, the method of radiodensitometry, developed during the last decade, is adopted: In the first investigation project the thicknesses of 800 annual rings are determined, in the second project 3808 annual ring structures are investigated, and in the third project 2000 annual rings are evaluated for their density characteristics. (orig./MG) [de

  20. [Investigation into the relationship between mitochondrial 12 S rRNA gene, tRNA gene and cytochrome oxidase Ⅱ gene variations and the risk of noise-induced hearing loss].

    Science.gov (United States)

    Jiao, J; Gu, G Z; Chen, G S; Li, Y H; Zhang, H L; Yang, Q Y; Xu, X R; Zhou, W H; Wu, H; He, L H; Zheng, Y X; Yu, S F

    2017-01-06

    Objective: To explore the relationship between mitochondrial 12 S rRNA gene variation, tRNA gene variation and cytochrome oxidase Ⅱ gene point mutations and the risk of noise-induced hearing loss (NIHL). Methods: A nested case-control study was performed that followed a cohort of 7 445 noise-exposed workers in a steel factory in Henan province, China, from January 1, 2006 to December 31, 2015. Subjects whose average hearing threshold was more than 40 dB(A) in high frequency were defined as the case group, and subjects whose average hearing threshold was less than 35 dB(A) in high frequency and less than 25 dB (A) in speech frequency were defined as the control group. Subjects was recruited into the case group ( n =286) and the control group ( n= 286) according to gender, age, job category and time of exposure to noise, and a 1∶1 case-control study was carried out. We genotyped eight single nucleotide polymorphisms in the mitochondrial 12 S rRNA gene, the mitochondrial tRNA gene and the mitochondrial cytochrome oxidase Ⅱ gene using SNPscan high-throughput genotyping technology from the recruited subjects. The relationship between polymorphic sites and NIHL, adjusted for covariates, was analyzed using conditional logistic regression analysis, as were the subgroup data. Results: The average age of the recruited subjects was (40.3±8.1) years and the length of service exposure to noise was (18.6±8.9) years. The range of noise exposed levels and cumulative noise exposure (CNE) was 80.1- 93.4 dB (A) and 86.8- 107.9 dB (A) · year, respectively. For workers exposed to noise at a CNE level<98 dB (A) · year, smokers showed an increased risk of NIHL of 1.88 (1.16-3.05) compared with non-smokers; for workers exposed to noise at a CNE level ≥98 dB(A) · year, smokers showed an increased risk of NIHL of 2.53 (1.49- 4.30) compared with non-smokers. For workers exposed to noise at a CNE level<98 dB (A) · year, the results of univariate analysis and multifactor analysis

  1. Influence of Design Variations on Systems Performance

    Science.gov (United States)

    Tumer, Irem Y.; Stone, Robert B.; Huff, Edward M.; Norvig, Peter (Technical Monitor)

    2000-01-01

    High-risk aerospace components have to meet very stringent quality, performance, and safety requirements. Any source of variation is a concern, as it may result in scrap or rework. poor performance, and potentially unsafe flying conditions. The sources of variation during product development, including design, manufacturing, and assembly, and during operation are shown. Sources of static and dynamic variation during development need to be detected accurately in order to prevent failure when the components are placed in operation. The Systems' Health and Safety (SHAS) research at the NASA Ames Research Center addresses the problem of detecting and evaluating the statistical variation in helicopter transmissions. In this work, we focus on the variations caused by design, manufacturing, and assembly of these components, prior to being placed in operation (DMV). In particular, we aim to understand and represent the failure and variation information, and their correlation to performance and safety and feed this information back into the development cycle at an early stage. The feedback of such critical information will assure the development of more reliable components with less rework and scrap. Variations during design and manufacturing are a common source of concern in the development and production of such components. Accounting for these variations, especially those that have the potential to affect performance, is accomplished in a variety ways, including Taguchi methods, FMEA, quality control, statistical process control, and variation risk management. In this work, we start with the assumption that any of these variations can be represented mathematically, and accounted for by using analytical tools incorporating these mathematical representations. In this paper, we concentrate on variations that are introduced during design. Variations introduced during manufacturing are investigated in parallel work.

  2. Ensembl variation resources

    Directory of Open Access Journals (Sweden)

    Marin-Garcia Pablo

    2010-05-01

    Full Text Available Abstract Background The maturing field of genomics is rapidly increasing the number of sequenced genomes and producing more information from those previously sequenced. Much of this additional information is variation data derived from sampling multiple individuals of a given species with the goal of discovering new variants and characterising the population frequencies of the variants that are already known. These data have immense value for many studies, including those designed to understand evolution and connect genotype to phenotype. Maximising the utility of the data requires that it be stored in an accessible manner that facilitates the integration of variation data with other genome resources such as gene annotation and comparative genomics. Description The Ensembl project provides comprehensive and integrated variation resources for a wide variety of chordate genomes. This paper provides a detailed description of the sources of data and the methods for creating the Ensembl variation databases. It also explores the utility of the information by explaining the range of query options available, from using interactive web displays, to online data mining tools and connecting directly to the data servers programmatically. It gives a good overview of the variation resources and future plans for expanding the variation data within Ensembl. Conclusions Variation data is an important key to understanding the functional and phenotypic differences between individuals. The development of new sequencing and genotyping technologies is greatly increasing the amount of variation data known for almost all genomes. The Ensembl variation resources are integrated into the Ensembl genome browser and provide a comprehensive way to access this data in the context of a widely used genome bioinformatics system. All Ensembl data is freely available at http://www.ensembl.org and from the public MySQL database server at ensembldb.ensembl.org.

  3. Variational Transition State Theory

    Energy Technology Data Exchange (ETDEWEB)

    Truhlar, Donald G. [Univ. of Minnesota, Minneapolis, MN (United States)

    2016-09-29

    This is the final report on a project involving the development and applications of variational transition state theory. This project involved the development of variational transition state theory for gas-phase reactions, including optimized multidimensional tunneling contributions and the application of this theory to gas-phase reactions with a special emphasis on developing reaction rate theory in directions that are important for applications to combustion. The development of variational transition state theory with optimized multidimensional tunneling as a useful computational tool for combustion kinetics involved eight objectives.

  4. Quantum variational calculus

    CERN Document Server

    Malinowska, Agnieszka B

    2014-01-01

    This Brief puts together two subjects, quantum and variational calculi by considering variational problems involving Hahn quantum operators. The main advantage of its results is that they are able to deal with nondifferentiable (even discontinuous) functions, which are important in applications. Possible applications in economics are discussed. Economists model time as continuous or discrete. Although individual economic decisions are generally made at discrete time intervals, they may well be less than perfectly synchronized in ways discrete models postulate. On the other hand, the usual assumption that economic activity takes place continuously, is nothing else than a convenient abstraction that in many applications is far from reality. The Hahn quantum calculus helps to bridge the gap between the two families of models: continuous and discrete. Quantum Variational Calculus is self-contained and unified in presentation. It provides an opportunity for an introduction to the quantum calculus of variations fo...

  5. Variational Monte Carlo Technique

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 19; Issue 8. Variational Monte Carlo Technique: Ground State Energies of Quantum Mechanical Systems. Sukanta Deb. General Article Volume 19 Issue 8 August 2014 pp 713-739 ...

  6. Variational principles in physics

    CERN Document Server

    Basdevant, Jean-Louis

    2007-01-01

    Optimization under constraints is an essential part of everyday life. Indeed, we routinely solve problems by striking a balance between contradictory interests, individual desires and material contingencies. This notion of equilibrium was dear to thinkers of the enlightenment, as illustrated by Montesquieu’s famous formulation: "In all magistracies, the greatness of the power must be compensated by the brevity of the duration." Astonishingly, natural laws are guided by a similar principle. Variational principles have proven to be surprisingly fertile. For example, Fermat used variational methods to demonstrate that light follows the fastest route from one point to another, an idea which came to be known as Fermat’s principle, a cornerstone of geometrical optics. Variational Principles in Physics explains variational principles and charts their use throughout modern physics. The heart of the book is devoted to the analytical mechanics of Lagrange and Hamilton, the basic tools of any physicist. Prof. Basdev...

  7. General quantum variational calculus

    Directory of Open Access Journals (Sweden)

    Artur M. C. Brito da Cruz

    2018-02-01

    Full Text Available We develop a new variational calculus based in the general quantum difference operator recently introduced by Hamza et al. In particular, we obtain optimality conditions for generalized variational problems where the Lagrangian may depend on the endpoints conditions and a real parameter, for the basic and isoperimetric problems, with and without fixed boundary conditions. Our results provide a generalization to previous results obtained for the $q$- and Hahn-calculus.

  8. Generalized quasi variational inequalities

    Energy Technology Data Exchange (ETDEWEB)

    Noor, M.A. [King Saud Univ., Riyadh (Saudi Arabia)

    1996-12-31

    In this paper, we establish the equivalence between the generalized quasi variational inequalities and the generalized implicit Wiener-Hopf equations using essentially the projection technique. This equivalence is used to suggest and analyze a number of new iterative algorithms for solving generalized quasi variational inequalities and the related complementarity problems. The convergence criteria is also considered. The results proved in this paper represent a significant improvement and refinement of the previously known results.

  9. Variational Integrals of a Class of Nonhomogeneous -Harmonic Equations

    Directory of Open Access Journals (Sweden)

    Guanfeng Li

    2014-01-01

    Full Text Available We introduce a class of variational integrals whose Euler equations are nonhomogeneous -harmonic equations. We investigate the relationship between the minimization problem and the Euler equation and give a simple proof of the existence of some nonhomogeneous -harmonic equations by applying direct methods of the calculus of variations. Besides, we establish some interesting results on variational integrals.

  10. Short-term variations of radiocarbon during the last century

    International Nuclear Information System (INIS)

    Burchuladze, A.A.; Pagava, S.V.; Jurina, V.; Povinec, P.; Usacev, S.

    1982-01-01

    Radiocarbon variations related to the 11-year solar cycle during the last century are discussed. Previous investigations on short term 14 C variations in tree rings are compared with 14 C measurements in Georgian wine samples. The amplitude of 14 C variations as obtained by various authors ranges from 0.2 to about 1%. (author)

  11. Variation as a main feature of norm

    Directory of Open Access Journals (Sweden)

    S. Poladova

    2017-09-01

    Full Text Available The past half-century has witnessed remarkable growth in the study of language variation, and it has now become a highly productive subfield of research in sociolinguistics. Variability is everywhere in language, from the unique details in each production of a sound or sign to the auditory or visual processing of the linguistic signal. All languages that we can observe today show variation; what is more, they vary in identical ways, namely geographically and socially. It’s no secret that languages like English are full of variation. So, the aim of the article is to detect the reasons of variation and to uncover rates of usage of different free variations for a given set of lexical items. The research work is carried out by using the descriptive, comparative methods by subjecting to analysis the specific language materials. The discovery of law of variation became a starting point for the evolution of linguistics. The problem of search of variation facts and its role in the functioning of language system concerns many specialists from the outset. The scope of the investigation was to set up a system out of chaos of phenomena. Currently, the fact of conditionality of variation by system relations existing in the language is considered to be established.

  12. Exploring subdomain variation in biomedical language

    Directory of Open Access Journals (Sweden)

    Séaghdha Diarmuid Ó

    2011-05-01

    Full Text Available Abstract Background Applications of Natural Language Processing (NLP technology to biomedical texts have generated significant interest in recent years. In this paper we identify and investigate the phenomenon of linguistic subdomain variation within the biomedical domain, i.e., the extent to which different subject areas of biomedicine are characterised by different linguistic behaviour. While variation at a coarser domain level such as between newswire and biomedical text is well-studied and known to affect the portability of NLP systems, we are the first to conduct an extensive investigation into more fine-grained levels of variation. Results Using the large OpenPMC text corpus, which spans the many subdomains of biomedicine, we investigate variation across a number of lexical, syntactic, semantic and discourse-related dimensions. These dimensions are chosen for their relevance to the performance of NLP systems. We use clustering techniques to analyse commonalities and distinctions among the subdomains. Conclusions We find that while patterns of inter-subdomain variation differ somewhat from one feature set to another, robust clusters can be identified that correspond to intuitive distinctions such as that between clinical and laboratory subjects. In particular, subdomains relating to genetics and molecular biology, which are the most common sources of material for training and evaluating biomedical NLP tools, are not representative of all biomedical subdomains. We conclude that an awareness of subdomain variation is important when considering the practical use of language processing applications by biomedical researchers.

  13. Sequences for Student Investigation

    Science.gov (United States)

    Barton, Jeffrey; Feil, David; Lartigue, David; Mullins, Bernadette

    2004-01-01

    We describe two classes of sequences that give rise to accessible problems for undergraduate research. These problems may be understood with virtually no prerequisites and are well suited for computer-aided investigation. The first sequence is a variation of one introduced by Stephen Wolfram in connection with his study of cellular automata. The…

  14. Fimbrial phase variation

    DEFF Research Database (Denmark)

    Khandige, Surabhi; Møller-Jensen, Jakob

    2016-01-01

    Surface fimbriae of pathogenic Escherichia coli facilitate sensing, adhesion and even invasion of host epithelial cells. While it is known that the pathogen has the potential to express a plethora of fimbrial variants susceptible to rapid phase ON/OFF variation, it is an open question if the fimb......Surface fimbriae of pathogenic Escherichia coli facilitate sensing, adhesion and even invasion of host epithelial cells. While it is known that the pathogen has the potential to express a plethora of fimbrial variants susceptible to rapid phase ON/OFF variation, it is an open question...... if the fimbrial diversity seen at the population level is the product of random stochasticity or a concerted effort based on active communication. Here we discuss the possibility of a mechanism alternative to a stochastic fimbrial phase variation model affecting the dynamics of a heterogeneous population....

  15. Variation, structure and norms

    DEFF Research Database (Denmark)

    Harder, Peter

    2014-01-01

    in linguistics: those that see linguistic norms as antithetical to a descriptive and variational linguistics. Once such a re-evaluation has taken place, however, the social recontextualization of cognition will enable linguistics (including sociolinguistics as an integral part), to eliminate the cracks...... that an evolutionary account can reintegrate the opposed fragments into a whole picture that puts each of them in their ‘ecological position’ with respect to each other. Empirical usage facts should be seen in the context of operational norms in relation to which actual linguistic choices represent adaptations....... Variational patterns should be seen in the context of structural categories without which there would be only ‘differences’ rather than variation. And emergence, individual choice, and flux should be seen in the context of the individual’s dependence on lineages of community practice sustained by collective...

  16. Ladder variational autoencoders

    DEFF Research Database (Denmark)

    Sønderby, Casper Kaae; Raiko, Tapani; Maaløe, Lars

    2016-01-01

    Variational autoencoders are powerful models for unsupervised learning. However deep models with several layers of dependent stochastic variables are difficult to train which limits the improvements obtained using these highly expressive models. We propose a new inference model, the Ladder...... Variational Autoencoder, that recursively corrects the generative distribution by a data dependent approximate likelihood in a process resembling the recently proposed Ladder Network. We show that this model provides state of the art predictive log-likelihood and tighter log-likelihood lower bound compared...

  17. Ladder Variational Autoencoder

    DEFF Research Database (Denmark)

    Sønderby, Casper Kaae; Raiko, Tapani; Maaløe, Lars

    2016-01-01

    Variational autoencoders are powerful models for unsupervised learning. However deep models with several layers of dependent stochastic variables are difficult to train which limits the improvements obtained using these highly expressive models. We propose a new inference model, the Ladder...... Variational Autoencoder, that recursively corrects the generative distribution by a data dependent approximate likelihood in a process resembling the recently proposed Ladder Network. We show that this model provides state of the art predictive log-likelihood and tighter log-likelihood lower bound compared...

  18. Splines and variational methods

    CERN Document Server

    Prenter, P M

    2008-01-01

    One of the clearest available introductions to variational methods, this text requires only a minimal background in calculus and linear algebra. Its self-contained treatment explains the application of theoretic notions to the kinds of physical problems that engineers regularly encounter. The text's first half concerns approximation theoretic notions, exploring the theory and computation of one- and two-dimensional polynomial and other spline functions. Later chapters examine variational methods in the solution of operator equations, focusing on boundary value problems in one and two dimension

  19. Cosmological constants and variations

    International Nuclear Information System (INIS)

    Barrow, John D

    2005-01-01

    We review properties of theories for the variation of the gravitation and fine structure 'constants'. We highlight some general features of the cosmological models that exist in these theories with reference to recent quasar data that is consistent with time-variation in the fine structure 'constant' since a redshift of 3.5. The behaviour of a simple class of varying alpha cosmologies is outlined in the light of all the observational constraints. We also discuss some of the consequences of varying 'constants' for oscillating universes and show by means of exact solutions that they appear to evolve monotonically in time even though the scale factor of the universe oscillates

  20. Variation and Linguistic Theory.

    Science.gov (United States)

    Bailey, Charles-James N.

    This volume presents principles and models for describing language variation, and introduces a time-based, dynamic framework for linguistic description. The book first summarizes some of the problems of grammatical description encountered from Saussure through the present and then outlines possibilities for new descriptions of language which take…

  1. On exterior variational calculus

    International Nuclear Information System (INIS)

    Aldrovandi, R.; Kraenkel, R.A.

    1987-01-01

    Exterior variational calculus is introduced through examples in field theory. It provides a very simple technique to decide on the existence of Lagrangians for given equations of motions and, in the case, to find them. Only local aspects are discussed but the analogy to exterior calculus on finite dimensional manifolds is complete, strongly suggesting its suitability to the study of topological aspects. (Author) [pt

  2. Variational transition state theory

    International Nuclear Information System (INIS)

    Truhlar, D.G.

    1986-01-01

    This project is concerned with the development and applications of generalized transition state theory and multidimensional tunneling approximations to chemical reaction rates. They have developed and implemented several practical versions of variational transition state theory (VTST), namely canonical variational theory (CVT), improved canonical variational theory (ICVT), and microcanonical variational theory (μVT). They have also developed and implemented several accurate multidimensional semiclassical tunneling approximations, the most accurate of which are the small-curvature semiclassical adiabatic (SCSA), large-curvature version-3 (LC3), and least-action (LA) approximations. They have applied the methods to thermal rate constants, using transmission coefficients based on ground-state tunneling, and they have also presented and applied adiabatic and diabatic extensions to calculated rate constants for vibrationally excited reactants. Their general goal is to develop accurate methods for calculating chemical reaction rate constants that remain practical even for reasonably complicated molecules. The approximations mentioned above yield rate constants for systems whose potential energy surface is known or assumed. Thus a second, equally important aspect of their work is the determination or modeling, semi-empirically and/or from electronic structure calculations, of potential energy surfaces

  3. Variation in decision making

    NARCIS (Netherlands)

    Dall, Sasha R. X.; Gosling, Samuel; Gordon D.A., Brown,; Dingemanse, Niels; Ido, Erev,; Martin, Kocher,; Laura, Schulz,; Todd, Peter M; Weissing, Franz; Wolf, Max; Hammerstein, Peter; Stevens, Jeffrey R.

    2012-01-01

    Variation in how organisms allocate their behavior over their lifetimes is key to determining Darwinian fitness., and thus the evolution of human and nonhuman decision making. This chapter explores how decision making varies across biologically and societally significant scales and what role such

  4. Seasonal Variation in Epidemiology

    Science.gov (United States)

    Marrero, Osvaldo

    2013-01-01

    Seasonality analyses are important in medical research. If the incidence of a disease shows a seasonal pattern, then an environmental factor must be considered in its etiology. We discuss a method for the simultaneous analysis of seasonal variation in multiple groups. The nuts and bolts are explained using simple trigonometry, an elementary…

  5. The variational spiked oscillator

    International Nuclear Information System (INIS)

    Aguilera-Navarro, V.C.; Ullah, N.

    1992-08-01

    A variational analysis of the spiked harmonic oscillator Hamiltonian -d 2 / d x 2 + x 2 + δ/ x 5/2 , δ > 0, is reported in this work. A trial function satisfying Dirichlet boundary conditions is suggested. The results are excellent for a large range of values of the coupling parameter. (author)

  6. Bounded variation and around

    CERN Document Server

    Appell, Jürgen; Merentes Díaz, Nelson José

    2013-01-01

    This monographis a self-contained exposition of the definition and properties of functionsof bounded variation and their various generalizations; the analytical properties of nonlinear composition operators in spaces of such functions; applications to Fourier analysis, nonlinear integral equations, and boundary value problems. The book is written for non-specialists. Every chapter closes with a list of exercises and open problems.

  7. Solar ultraviolet irradiance variations: a review

    International Nuclear Information System (INIS)

    Lean, J.

    1987-01-01

    Despite the geophysical importance of solar ultraviolet radiation, specific aspects of its temporal variations have not yet been adequately determined experimentally, nor are the mechanisms for the variability completely understood. Satellite observations have verified the reality of solar ultraviolet irradiance variations over time scales of days and months, and model calculations have confirmed the association of these short-term variations with the evolution and rotation of regions of enhanced magnetic activity on the solar disc. However, neither rocket nor satellite measurements have yet been made with sufficient accuracy and regularity to establish unequivocally the nature of the variability over the longer time of the 11-year solar cycle. The comparative importance for the long-term variations of local regions of enhanced magnetic activity and global scale activity perturbations is still being investigated. Solar ultraviolet irradiance variations over both short and long time scales are reviewed, with emphasis on their connection to solar magnetic activity. Correlations with ground-based measures of solar variability are examined because of the importance of the ground-based observations as historical proxies of ultraviolet irradiance variations. Current problems in understanding solar ultraviolet irradiance variations are discussed, and the measurements planned for solar cycle 22, which may resolve these problems, are briefly described. copyright American Geophysical Union 1987

  8. Investigation of W/O microemulsion droplets by contrast variation ...

    Indian Academy of Sciences (India)

    various molar ratios (µ) of water to AOT and temperatures on water-in-oil (W/O) mi- croemulsions dispersed in n-heptane, ... tures composed of surfactant, water, and oil have attracted much interest since they form thermodynamically stable phases .... filter into dust-free sample cells. The cylindrical sample cells are made of ...

  9. Vowel variation in Southern Sotho: an acoustic investigation

    CSIR Research Space (South Africa)

    Barnard, E

    2008-01-01

    Full Text Available the developers of HLT systems to select from sometimes contradictory accounts of basic linguistic facts (while somehow filling in those portions that are necessary for their systems but not available in the published literature). For spoken language... Linguistics and Applied Language Studies 2008, 26(2): 255?265 Printed in South Africa ? All rights reserved Copyright ? NISC Pty Ltd SOUTHERN AFRICAN LINGUISTICS AND APPLIED LANGUAGE STUDIES ISSN 1607?3614 EISSN 1727?9461 DOI: 10.2989/SALALS.2008...

  10. Investigation of Seasonal Variation of groundwater Quality in Jimeta ...

    African Journals Online (AJOL)

    Sadiq

    chloride exceeded the recommended standards of drinking water quality in the rainy season ... supply, hygiene and exacerbating public health (Okoro ... source for human consumption and changes in quality ... Nigeria, has affected the availability of groundwater due .... carried out to define the impacts of waste water on.

  11. Transducer frequency response variations investigated by time reversal calibration

    Czech Academy of Sciences Publication Activity Database

    Kober, Jan; Převorovský, Zdeněk

    2016-01-01

    Roč. 26, č. 2 (2016), A16-A16 ISSN 1213-3825. [Europen Conference on Acoustic Emission Testing /32./. 07.09.2016-09.09.2016, Praha] Institutional support: RVO:61388998 Keywords : calibration * time reversal * transducer * frequency response Subject RIV: BI - Acoustics

  12. Variation tolerant SoC design

    Science.gov (United States)

    Kozhikkottu, Vivek J.

    allocation of shared system resources as a means to combat the adverse impact of within-die variations on multi-core platforms. For multi-threaded programs executing on variation-impacted multi-cores platforms, we make the key observation that thread performance is not only a function of the frequency of the core on which it is executing on, but also depends upon the amount of shared system resources allocated to it. We utilize this insight to design a variation-aware runtime scheme which allocates the ways of a last-level shared L2 cache amongst the different cores/threads of a multi-core platform taking into account both application characteristics as well as chip specific variation profiles. Our experiments on 100 quad-core chips, each with a distinct variation profile, shows on an average 15% performance improvements for a suite of multi-threaded benchmarks. Our final contribution investigates the variation-tolerant design of domain-specific accelerators and demonstrates how the unique architectural properties of these accelerators can be leveraged to create highly effective variation tolerance mechanisms. We explore this concept through the variation-tolerant design of a vector processor that efficiently executes applications from the domains of recognition, mining and synthesis (RMS). We develop a novel design approach for variation tolerance, which leverages the unique nature of the vector reduction operations performed by this processor to effectively predict and preempt the occurrence of timing errors under variations and subsequently restore the correct output at the end of each vector reduction operation. We implement the above predict, preempt and restore operations by suitably enhancing the processor hardware and the application software and demonstrate considerable energy benefits (on an average 32%) across six applications from the domains of RMS. In conclusion, our work provides system designers with powerful tools and mechanisms in their efforts to combat

  13. Conformable variational iteration method

    Directory of Open Access Journals (Sweden)

    Omer Acan

    2017-02-01

    Full Text Available In this study, we introduce the conformable variational iteration method based on new defined fractional derivative called conformable fractional derivative. This new method is applied two fractional order ordinary differential equations. To see how the solutions of this method, linear homogeneous and non-linear non-homogeneous fractional ordinary differential equations are selected. Obtained results are compared the exact solutions and their graphics are plotted to demonstrate efficiency and accuracy of the method.

  14. Diurnal variations of Titan's ionosphere

    Science.gov (United States)

    Cui, J.; Galand, M.; Yelle, R. V.; Vuitton, V.; Wahlund, J.-E.; Lavvas, P. P.; Müller-Wodarg, I. C. F.; Cravens, T. E.; Kasprzak, W. T.; Waite, J. H.

    2009-06-01

    We present our analysis of the diurnal variations of Titan's ionosphere (between 1000 and 1300 km) based on a sample of Ion Neutral Mass Spectrometer (INMS) measurements in the Open Source Ion (OSI) mode obtained from eight close encounters of the Cassini spacecraft with Titan. Although there is an overall ion depletion well beyond the terminator, the ion content on Titan's nightside is still appreciable, with a density plateau of ˜700 cm-3 below ˜1300 km. Such a plateau is a combined result of significant depletion of light ions and modest depletion of heavy ones on Titan's nightside. We propose that the distinctions between the diurnal variations of light and heavy ions are associated with their different chemical loss pathways, with the former primarily through “fast” ion-neutral chemistry and the latter through “slow” electron dissociative recombination. The strong correlation between the observed night-to-day ion density ratios and the associated ion lifetimes suggests a scenario in which the ions created on Titan's dayside may survive well to the nightside. The observed asymmetry between the dawn and dusk ion density profiles also supports such an interpretation. We construct a time-dependent ion chemistry model to investigate the effect of ion survival associated with solid body rotation alone as well as superrotating horizontal winds. For long-lived ions, the predicted diurnal variations have similar general characteristics to those observed. However, for short-lived ions, the model densities on the nightside are significantly lower than the observed values. This implies that electron precipitation from Saturn's magnetosphere may be an additional and important contributor to the densities of the short-lived ions observed on Titan's nightside.

  15. Somaclonal variation in rice

    International Nuclear Information System (INIS)

    Kucherenko, L.

    1990-01-01

    Full text: 32 varieties of Oryza sativa L. ssp. japonica were used as donors for callus induction from somatic tissues. In some cases, the callus was treated before regeneration with the chemical mutagen MNU. Some of the regenerated plants demonstrated heritable alterations, among them chlorophyll deficiencies, variation in plant height, awness, glume colouring and fertility. Along with these, a number of lines with agronomically valuable alterations concerning maturity time, panicle structure, plant productivity and grain quality were found. The spectrum of variability was very wide. Vivipary was noticed. Superdwarfs with plant height of about 15 cm were found. Plants with no visible distinctions could be variants too, for example, with increased protein content or disease resistance. The rate and the spectrum of the somaclonal variation were not influenced by the culture media but depended on the donor's genotype. On the basis of somaclonal variation a variety 'Bioryza' was developed. It is an early maturing (about 95-100 days), long grain variety, with grain yield up to 8 t/ha. (author)

  16. Canonical variate regression.

    Science.gov (United States)

    Luo, Chongliang; Liu, Jin; Dey, Dipak K; Chen, Kun

    2016-07-01

    In many fields, multi-view datasets, measuring multiple distinct but interrelated sets of characteristics on the same set of subjects, together with data on certain outcomes or phenotypes, are routinely collected. The objective in such a problem is often two-fold: both to explore the association structures of multiple sets of measurements and to develop a parsimonious model for predicting the future outcomes. We study a unified canonical variate regression framework to tackle the two problems simultaneously. The proposed criterion integrates multiple canonical correlation analysis with predictive modeling, balancing between the association strength of the canonical variates and their joint predictive power on the outcomes. Moreover, the proposed criterion seeks multiple sets of canonical variates simultaneously to enable the examination of their joint effects on the outcomes, and is able to handle multivariate and non-Gaussian outcomes. An efficient algorithm based on variable splitting and Lagrangian multipliers is proposed. Simulation studies show the superior performance of the proposed approach. We demonstrate the effectiveness of the proposed approach in an [Formula: see text] intercross mice study and an alcohol dependence study. © The Author 2016. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  17. Evaluation of natural language processing from emergency department computerized medical records for intra-hospital syndromic surveillance

    Directory of Open Access Journals (Sweden)

    Pagliaroli Véronique

    2011-07-01

    Full Text Available Abstract Background The identification of patients who pose an epidemic hazard when they are admitted to a health facility plays a role in preventing the risk of hospital acquired infection. An automated clinical decision support system to detect suspected cases, based on the principle of syndromic surveillance, is being developed at the University of Lyon's Hôpital de la Croix-Rousse. This tool will analyse structured data and narrative reports from computerized emergency department (ED medical records. The first step consists of developing an application (UrgIndex which automatically extracts and encodes information found in narrative reports. The purpose of the present article is to describe and evaluate this natural language processing system. Methods Narrative reports have to be pre-processed before utilizing the French-language medical multi-terminology indexer (ECMT for standardized encoding. UrgIndex identifies and excludes syntagmas containing a negation and replaces non-standard terms (abbreviations, acronyms, spelling errors.... Then, the phrases are sent to the ECMT through an Internet connection. The indexer's reply, based on Extensible Markup Language, returns codes and literals corresponding to the concepts found in phrases. UrgIndex filters codes corresponding to suspected infections. Recall is defined as the number of relevant processed medical concepts divided by the number of concepts evaluated (coded manually by the medical epidemiologist. Precision is defined as the number of relevant processed concepts divided by the number of concepts proposed by UrgIndex. Recall and precision were assessed for respiratory and cutaneous syndromes. Results Evaluation of 1,674 processed medical concepts contained in 100 ED medical records (50 for respiratory syndromes and 50 for cutaneous syndromes showed an overall recall of 85.8% (95% CI: 84.1-87.3. Recall varied from 84.5% for respiratory syndromes to 87.0% for cutaneous syndromes. The most frequent cause of lack of processing was non-recognition of the term by UrgIndex (9.7%. Overall precision was 79.1% (95% CI: 77.3-80.8. It varied from 81.4% for respiratory syndromes to 77.0% for cutaneous syndromes. Conclusions This study demonstrates the feasibility of and interest in developing an automated method for extracting and encoding medical concepts from ED narrative reports, the first step required for the detection of potentially infectious patients at epidemic risk.

  18. On polar daily geomagnetic variation

    Directory of Open Access Journals (Sweden)

    Paola De Michelis

    2015-11-01

    Full Text Available The aim of this work is to investigate the nature of the daily magnetic field perturbations produced by ionospheric and magnetospheric currents at high latitudes. We analyse the hourly means of the X and Y geomagnetic field components recorded by a meridian chain of permanent geomagnetic observatories in the polar region of the Northern Hemisphere during a period of four years (1995-1998 around the solar minimum. We apply a mathematical method, known as natural orthogonal component (NOC, which is capable of characterizing the dominant modes of the geomagnetic field daily variability through a set of empirical orthogonal functions (EOFs. Using the first two modes we reconstruct a two-dimensional equivalent current representation of the ionospheric electric currents, which contribute substantially to the geomagnetic daily variations. The obtained current structures resemble the equivalent current patterns of DP2 and DP1. We characterize these currents by studying their evolution with the geomagnetic activity level and by analysing their dependence on the interplanetary magnetic field. The obtained results support the idea of a coexistence of two main processes during all analysed period although one of them, the directly driven process, represents the dominant component of the geomagnetic daily variation.

  19. Massless quantum electrodynamics: a variational study

    International Nuclear Information System (INIS)

    Piquini, P.C.

    1990-01-01

    The variational method was used to study the probable existence of a compound vacuum in quantum electrodynamics. An Ansatz containing a condensate of electron-positron pairs was investigated and an optimization equation for the condensate wave function found. (L.C.J.A.)

  20. Genetic variation of contact dermatitis in broilers

    DEFF Research Database (Denmark)

    Ask, Birgitte

    2010-01-01

    This study aimed to investigate the presence of genetic variation in footpad dermatitis (FPD) and hock burns (HB) and the possibility to genetically select against these. A field trial including 10 commercial broiler lines (n = 102 to 265) was carried out at 2 Dutch farms. Footpad dermatitis and HB...

  1. Equilibrium models and variational inequalities

    CERN Document Server

    Konnov, Igor

    2007-01-01

    The concept of equilibrium plays a central role in various applied sciences, such as physics (especially, mechanics), economics, engineering, transportation, sociology, chemistry, biology and other fields. If one can formulate the equilibrium problem in the form of a mathematical model, solutions of the corresponding problem can be used for forecasting the future behavior of very complex systems and, also, for correcting the the current state of the system under control. This book presents a unifying look on different equilibrium concepts in economics, including several models from related sciences.- Presents a unifying look on different equilibrium concepts and also the present state of investigations in this field- Describes static and dynamic input-output models, Walras, Cassel-Wald, spatial price, auction market, oligopolistic equilibrium models, transportation and migration equilibrium models- Covers the basics of theory and solution methods both for the complementarity and variational inequality probl...

  2. Genomic Sequence Variation Markup Language (GSVML).

    Science.gov (United States)

    Nakaya, Jun; Kimura, Michio; Hiroi, Kaei; Ido, Keisuke; Yang, Woosung; Tanaka, Hiroshi

    2010-02-01

    With the aim of making good use of internationally accumulated genomic sequence variation data, which is increasing rapidly due to the explosive amount of genomic research at present, the development of an interoperable data exchange format and its international standardization are necessary. Genomic Sequence Variation Markup Language (GSVML) will focus on genomic sequence variation data and human health applications, such as gene based medicine or pharmacogenomics. We developed GSVML through eight steps, based on case analysis and domain investigations. By focusing on the design scope to human health applications and genomic sequence variation, we attempted to eliminate ambiguity and to ensure practicability. We intended to satisfy the requirements derived from the use case analysis of human-based clinical genomic applications. Based on database investigations, we attempted to minimize the redundancy of the data format, while maximizing the data covering range. We also attempted to ensure communication and interface ability with other Markup Languages, for exchange of omics data among various omics researchers or facilities. The interface ability with developing clinical standards, such as the Health Level Seven Genotype Information model, was analyzed. We developed the human health-oriented GSVML comprising variation data, direct annotation, and indirect annotation categories; the variation data category is required, while the direct and indirect annotation categories are optional. The annotation categories contain omics and clinical information, and have internal relationships. For designing, we examined 6 cases for three criteria as human health application and 15 data elements for three criteria as data formats for genomic sequence variation data exchange. The data format of five international SNP databases and six Markup Languages and the interface ability to the Health Level Seven Genotype Model in terms of 317 items were investigated. GSVML was developed as

  3. Coarse Grained Exponential Variational Autoencoders

    KAUST Repository

    Sun, Ke; Zhang, Xiangliang

    2017-01-01

    Variational autoencoders (VAE) often use Gaussian or category distribution to model the inference process. This puts a limit on variational learning because this simplified assumption does not match the true posterior distribution, which is usually

  4. Variational submanifolds of Euclidean spaces

    Science.gov (United States)

    Krupka, D.; Urban, Z.; Volná, J.

    2018-03-01

    Systems of ordinary differential equations (or dynamical forms in Lagrangian mechanics), induced by embeddings of smooth fibered manifolds over one-dimensional basis, are considered in the class of variational equations. For a given non-variational system, conditions assuring variationality (the Helmholtz conditions) of the induced system with respect to a submanifold of a Euclidean space are studied, and the problem of existence of these "variational submanifolds" is formulated in general and solved for second-order systems. The variational sequence theory on sheaves of differential forms is employed as a main tool for the analysis of local and global aspects (variationality and variational triviality). The theory is illustrated by examples of holonomic constraints (submanifolds of a configuration Euclidean space) which are variational submanifolds in geometry and mechanics.

  5. Introduction to global variational geometry

    CERN Document Server

    Krupka, Demeter

    2015-01-01

    The book is devoted to recent research in the global variational theory on smooth manifolds. Its main objective is an extension of the classical variational calculus on Euclidean spaces to (topologically nontrivial) finite-dimensional smooth manifolds; to this purpose the methods of global analysis of differential forms are used. Emphasis is placed on the foundations of the theory of variational functionals on fibered manifolds - relevant geometric structures for variational principles in geometry, physical field theory and higher-order fibered mechanics. The book chapters include: - foundations of jet bundles and analysis of differential forms and vector fields on jet bundles, - the theory of higher-order integral variational functionals for sections of a fibred space, the (global) first variational formula in infinitesimal and integral forms- extremal conditions and the discussion of Noether symmetries and generalizations,- the inverse problems of the calculus of variations of Helmholtz type- variational se...

  6. Gauging Variational Inference

    Energy Technology Data Exchange (ETDEWEB)

    Chertkov, Michael [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Ahn, Sungsoo [Korea Advanced Inst. Science and Technology (KAIST), Daejeon (Korea, Republic of); Shin, Jinwoo [Korea Advanced Inst. Science and Technology (KAIST), Daejeon (Korea, Republic of)

    2017-05-25

    Computing partition function is the most important statistical inference task arising in applications of Graphical Models (GM). Since it is computationally intractable, approximate methods have been used to resolve the issue in practice, where meanfield (MF) and belief propagation (BP) are arguably the most popular and successful approaches of a variational type. In this paper, we propose two new variational schemes, coined Gauged-MF (G-MF) and Gauged-BP (G-BP), improving MF and BP, respectively. Both provide lower bounds for the partition function by utilizing the so-called gauge transformation which modifies factors of GM while keeping the partition function invariant. Moreover, we prove that both G-MF and G-BP are exact for GMs with a single loop of a special structure, even though the bare MF and BP perform badly in this case. Our extensive experiments, on complete GMs of relatively small size and on large GM (up-to 300 variables) confirm that the newly proposed algorithms outperform and generalize MF and BP.

  7. Variations in brain DNA

    Directory of Open Access Journals (Sweden)

    Jesus eAvila

    2014-11-01

    Full Text Available It is assumed that DNA sequences are conserved in the diverse cell types present in a multicellular organism like the human being. Thus, in order to compare the sequences in the genome of DNA from different individuals, nucleic acid is commonly isolated from a single tissue. In this regard, blood cells are widely used for this purpose because of their availability. Thus blood DNA has been used to study genetic familiar diseases that affect other tissues and organs, such as the liver, heart, and brain. While this approach is valid for the identification of familial diseases in which mutations are present in parental germinal cells and, therefore, in all the cells of a given organism, it is not suitable to identify sporadic diseases in which mutations might occur in specific somatic cells. This review addresses somatic DNA variations in different tissues or cells (mainly in the brain of single individuals and discusses whether the dogma of DNA invariance between cell types is indeed correct. We will also discuss how single nucleotide somatic variations arise, focusing on the presence of specific DNA mutations in the brain.

  8. Harmonically excited orbital variations

    International Nuclear Information System (INIS)

    Morgan, T.

    1985-01-01

    Rephrasing the equations of motion for orbital maneuvers in terms of Lagrangian generalized coordinates instead of Newtonian rectangular cartesian coordinates can make certain harmonic terms in the orbital angular momentum vector more readily apparent. In this formulation the equations of motion adopt the form of a damped harmonic oscillator when torques are applied to the orbit in a variationally prescribed manner. The frequencies of the oscillator equation are in some ways unexpected but can nonetheless be exploited through resonant forcing functions to achieve large secular variations in the orbital elements. Two cases are discussed using a circular orbit as the control case: (1) large changes in orbital inclination achieved by harmonic excitation rather than one impulsive velocity change, and (2) periodic and secular changes to the longitude of the ascending node using both stable and unstable excitation strategies. The implications of these equations are also discussed for both artificial satellites and natural satellites. For the former, two utilitarian orbits are suggested, each exploiting a form of harmonic excitation. 5 refs

  9. Variationally Asymptotically Stable Difference Systems

    Directory of Open Access Journals (Sweden)

    Goo YoonHoe

    2007-01-01

    Full Text Available We characterize the h-stability in variation and asymptotic equilibrium in variation for nonlinear difference systems via n∞-summable similarity and comparison principle. Furthermore we study the asymptotic equivalence between nonlinear difference systems and their variational difference systems by means of asymptotic equilibria of two systems.

  10. Evaluation of variational approximations

    International Nuclear Information System (INIS)

    Trevisan, L.A.

    1991-01-01

    In Feynman's approach to quantum statistical mechanics, the partition function can e represented as a path integral. A recently proposed variation method of Feynman-Kleinert is able to transform the path integral into an integral in phase space, in which the quantum fluctuations have been taken care of by introducing the effective classical potential. This method has been testes with succeed for the smooth potentials and for the singular potential of delta. The method to the strong singular potentials is applied: a quadratic potential and a linear potential both with a rigid wall at the origin. By satisfying the condition that the density of the particle be vanish at the origin, and adapted method of Feynman-Kleinert in order to improve the method is introduced. (author)

  11. Investigative psychology

    OpenAIRE

    Canter, David V.

    2010-01-01

    The domain of Investigative Psychology covers all aspects of psychology that are relevant to the conduct of criminal or civil investigations. Its focus is on the ways in which criminal activities may be examined and understood in order for the detection of crime to be effective and legal proceedings to be appropriate. As such Investigative Psychology is concerned with psychological input to the full range of issues that relate to the management, investigation and prosecution of crime

  12. Dynamics of nonholonomic systems from variational principles embedded variation identity

    International Nuclear Information System (INIS)

    Guo Yongxin; Liu Shixing; Liu Chang; Chang Peng

    2009-01-01

    Nondeterminacy of dynamics, i.e., the nonholonomic or the vakonomic, fundamental variational principles, e.g., the Lagrange-d'Alembert or Hamiltonian, and variational operators, etc., of nonholonomic mechanical systems can be attributed to the non-uniqueness of ways how to realize nonholonomic constraints. Making use of a variation identity of nonholonomic constraints embedded into the Hamilton's principle with the method of Lagrange undetermined multipliers, three kinds of dynamics for the nonholonomic systems including the vakonomic and nonholonomic ones and a new one are obtained if the variation is respectively reduced to three conditional variations: vakonomic variation, Hoelder's variation and Suslov's variation, defined by the identity. Therefore, different dynamics of nonholonomic systems can be derived from an integral variational principle, utilizing one way of embedding constraints into the principle, with different variations. It is verified that the similar embedding of the identity into the Lagrange-d'Alembert principle gives rise to the nonholonomic dynamics but fails to give the vakonomic one unless the constraints are integrable.

  13. Dynamics of nonholonomic systems from variational principles embedded variation identity

    Energy Technology Data Exchange (ETDEWEB)

    Guo Yongxin, E-mail: yxguo@lnu.edu.c [College of Physics, Liaoning University, Shenyang 110036 (China); Liu Shixing [College of Physics, Liaoning University, Shenyang 110036 (China); Liu Chang; Chang Peng [Department of Applied Mechanics, Beijing Institute of Technology, Beijing 100081 (China)

    2009-10-19

    Nondeterminacy of dynamics, i.e., the nonholonomic or the vakonomic, fundamental variational principles, e.g., the Lagrange-d'Alembert or Hamiltonian, and variational operators, etc., of nonholonomic mechanical systems can be attributed to the non-uniqueness of ways how to realize nonholonomic constraints. Making use of a variation identity of nonholonomic constraints embedded into the Hamilton's principle with the method of Lagrange undetermined multipliers, three kinds of dynamics for the nonholonomic systems including the vakonomic and nonholonomic ones and a new one are obtained if the variation is respectively reduced to three conditional variations: vakonomic variation, Hoelder's variation and Suslov's variation, defined by the identity. Therefore, different dynamics of nonholonomic systems can be derived from an integral variational principle, utilizing one way of embedding constraints into the principle, with different variations. It is verified that the similar embedding of the identity into the Lagrange-d'Alembert principle gives rise to the nonholonomic dynamics but fails to give the vakonomic one unless the constraints are integrable.

  14. MtDNA T4216C variation in multiple sclerosis

    DEFF Research Database (Denmark)

    Andalib, Sasan; Emamhadi, Mohammadreza; Yousefzadeh-Chabok, Shahrokh

    2016-01-01

    MtDNA T4216C variation has frequently been investigated in Multiple Sclerosis (MS) patients; nonetheless, controversy has existed about the evidence of association of this variation with susceptibility to MS. The present systematic review and meta-analysis converge the results of the preceding pu...

  15. Task demands and individual variation in referring expressions

    NARCIS (Netherlands)

    Baltaretu, Adriana-Alexandra; Castro Ferreira, Thiago

    Aiming to improve the human-likeness of natural language generation systems, this study investigates different sources of variation that might influence the production of referring expressions (REs), namely the effect of task demands and inter- intra- individual variation. We collected REs using a

  16. Variational formulation based analysis on growth of yield front in ...

    African Journals Online (AJOL)

    The present study investigates the growth of elastic-plastic front in rotating solid disks of non-uniform thickness having exponential and parabolic geometry variation. The problem is solved through an extension of a variational method in elastoplastic regime. The formulation is based on von-Mises yield criterion and linear ...

  17. Variation in VIP latrine sludge contents | Bakare | Water SA

    African Journals Online (AJOL)

    This study investigated variations in the characteristics of the sludge content from different ventilated improved pit (VIP) latrines and variation in these characteristics at specific depths within each pit. Faecal sludge from 16 VIP latrines within the eThekwini Municipality was collected and laboratory characterisation including ...

  18. Annual variation in the net longshore sediment transport rate

    CSIR Research Space (South Africa)

    Schoonees, JS

    2000-05-01

    Full Text Available The annual variation in the net long shore sediment transport rates at three South African and at one North African site is investigated. The net rates at these sites, given in the first table, showed large variations. It was found that measurements...

  19. Seismic noise level variation in South Korea

    Science.gov (United States)

    Sheen, D.; Shin, J.

    2008-12-01

    The variations of seismic background noise in South Korea have been investigated by means of power spectral analysis. The Korea Institute of Geoscience and Mineral Resources (KIGAM) and the Korea Meteorological Administation (KMA) have national wide seismic networks in South Korea, and, in the end of 2007, there are 30 broadband stations which have been operating for more than a year. In this study, we have estimated the power spectral density of seismic noise for 30 broadband stations from 2005 to 2007. Since we estimate PSDs from a large dataset of continuous waveform in this study, a robust PSD estimate of McNamara and Buland (2004) is used. In the frequency range 1-5 Hz, the diurnal variations of noise are observed at most of stations, which are especially larger at coastal stations and at insular than at inland. Some stations shows daily difference of diurnal variations, which represents that cultural activities contribute to the noise level of a station. The variation of number of triggered stations, however, shows that cultural noise has little influence on the detection capability of seismic network in South Korea. Seasonal variations are observed well in the range 0.1-0.5 Hz, while much less found in the frequency range 1-5 Hz. We observed that strong peaks in the range 0.1-0.5 Hz occur at the summer when Pacific typhoons are close to the Korean Peninsula.

  20. Testing the Processing Hypothesis of word order variation using a probabilistic language model

    NARCIS (Netherlands)

    Bloem, J.

    2016-01-01

    This work investigates the application of a measure of surprisal to modeling a grammatical variation phenomenon between near-synonymous constructions. We investigate a particular variation phenomenon, word order variation in Dutch two-verb clusters, where it has been established that word order

  1. Variations in the magnetopause current layer

    Science.gov (United States)

    Laakso, H. E.; Middleton, H. R.

    2017-12-01

    We use multi-point observations from the Cluster spacecraft to investigate the variations in the magnetopause current layer. With help of the curlometer technique one can determine the magnetopause current and its variability. Most of the time the magnetopause location is moving back and forth, so during any given pass the current layer is crossed several times. We use such crossings to investigate the characteristics of the current layer as the solar wind pressure varies (and the magnetopause moves accordingly). In addition we take an advantage of the ambient electron measurements from the EDI experiment which have been calibrated against the PEACE electron spectrometer data. These data can be used to detect fast variations of 1 keV electrons at resolution of 1-100 ms. Overall, Cluster observations are highly complimentary to the MMS observations due to the polar orbit of the Cluster spacecraft which provide fast vertical profiles of the magnetopause current layer.

  2. Geographical variation and the determinants of domestic endotoxin levels in mattress dust in Europe

    NARCIS (Netherlands)

    Chen, C.M.; Thiering, E.; Doekes, G.; Zock, J.P.; Bakolis, I.; Norbäck, D.; Sunyer, J.; Villani, S.; Verlato, G.; Täubel, M.; Jarvis, D.

    2012-01-01

    Endotoxin exposures have manifold effects on human health. The geographical variation and determinants of domestic endotoxin levels in Europe have not yet been extensively described. To investigate the geographical variation and determinants of domestic endotoxin concentrations in mattress dust in

  3. Event Investigation

    International Nuclear Information System (INIS)

    Korosec, D.

    2000-01-01

    The events in the nuclear industry are investigated from the license point of view and from the regulatory side too. It is well known the importance of the event investigation. One of the main goals of such investigation is to prevent the circumstances leading to the event and the consequences of the event. The protection of the nuclear workers against nuclear hazard, and the protection of general public against dangerous effects of an event could be achieved by systematic approach to the event investigation. Both, the nuclear safety regulatory body and the licensee shall ensure that operational significant events are investigated in a systematic and technically sound manner to gather information pertaining to the probable causes of the event. One of the results should be appropriate feedback regarding the lessons of the experience to the regulatory body, nuclear industry and general public. In the present paper a general description of systematic approach to the event investigation is presented. The systematic approach to the event investigation works best where cooperation is present among the different divisions of the nuclear facility or regulatory body. By involving management and supervisors the safety office can usually improve their efforts in the whole process. The end result shall be a program which serves to prevent events and reduce the time and efforts solving the root cause which initiated each event. Selection of the proper method for the investigation and an adequate review of the findings and conclusions lead to the higher level of the overall nuclear safety. (author)

  4. A survey of variational principles

    International Nuclear Information System (INIS)

    Lewins, J.D.

    1993-01-01

    In this article survey of variational principles has been given. Variational principles play a significant role in mathematical theory with emphasis on the physical aspects. There are two principals used i.e. to represent the equation of the system in a succinct way and to enable a particular computation in the system to be carried out with greater accuracy. The survey of variational principles has ranged widely from its starting point in the Lagrange multiplier to optimisation principles. In an age of digital computation, these classic methods can be adapted to improve such calculations. We emphasize particularly the advantage of basic finite element methods on variational principles. (A.B.)

  5. Stored ions in the Paul trap. Preliminary investigations on life-time measurement of the metastable 6D3/2 state of 226Ra+, storage properties of 138Ba+ and 28N2+ at variation of the buffer-gas pressure

    International Nuclear Information System (INIS)

    Leuthner, Heiko

    2011-01-01

    Paul-traps are a widely used tool in scientific research and play an important role in atomic physics and mass spectrometry. (1) From the earth-alkaline ions only spectroscopic data of Ra + are lacking. Those are important for the test of theoretical models and for a future atomic parity violation experiment. The first part of this work describes the setting up of a Paul-trap based Laser-experiment for measuring the lifetime of the 6D 3/2 state of 226 Ra + . Basic tests with 138 Ba + ions are presented. (2) Damping and space charge effects on resonances in the stability region strongly affect the use of Paul-traps in mass spectrometry and analysis of reaction products. The second part of this work presents detailed investigations on the storage of big, buffer-gas-cooled ion clouds in two different Paul-trap experiments; the first of them uses 138 Ba + ions detected continuously by electronic and optical detection systems, the second one uses N 2 + molecular ions and an automated destructive time-of-flight-detection method. A high precision measurement with N 2 + of the first stability region of the trap not only gives the possibility of direct comparison of experimental and theoretical resonances but also provides absolute ion numbers over the whole region for the first time. Unlike previous measurements, the investigations on nonlinear resonances where done on the superimposed stability regions of 4 simultaneously stored ion species. The nonlinear resonances were studied by varying buffer gas pressure and ion number and showed collective resonances without external excitation. By varying the buffer gas pressure the spatial distribution of a Ba + -ion cloud was investigated as well as the change of the optimal storing parameters using N 2 + -ions. Optimum Pressures for catching and trapping of ions turned out to be unequal. Shape and position of externally excited collective and individual resonances were studied under variation of ion number, buffer-gas pressure

  6. A variational approach to closed bosonic strings on bordered Riemann surfaces

    International Nuclear Information System (INIS)

    Ohrndorf, T.

    1987-01-01

    Polyakov's path integral for bosonic closed strings defined on a bordered Riemann surface is investigated by variational methods. It is demonstrated that boundary variations are generated by the Virasoro operators. The investigation is performed for both, simply connected Riemann surfaces as well as ringlike domains. It is shown that the form of the variational operator is the same on both kinds of surfaces. The Virasoro algebra arises as a consistency condition for the variation. (orig.)

  7. Seasonal variation in food allergy to apple

    DEFF Research Database (Denmark)

    Skamstrup Hansen, K; Vieths, S; Vestergaard, H

    2001-01-01

    The aim of the study was to investigate the possibility of a seasonal variation in reactivity to apples in 27 birch pollen allergic patients. Before and during the birch pollen season 1998, the patients were subjected to double-blind, placebo-controlled food challenges (DBPCFCs) with grated fresh...... Golden Delicious apple followed by an open food challenge with whole fresh apple. The clinical reactions elicited during the challenges were evaluated both by the patients and the investigators. Moreover, the skin reactivity and the in vitro reactivity to apple were evaluated by skin prick test (SPT...

  8. Exploiting natural variation in Arabidopsis

    NARCIS (Netherlands)

    Molenaar, J.A.; Keurentjes, J.J.B.; Sanchez-Serrano, J.J.; Salinas, J.

    2014-01-01

    Natural variation for many traits is present within the species Arabidopsis thaliana. This chapter describes the use of natural variation to elucidate genes underlying the regulation of quantitative traits. It deals with the development and use of mapping populations, the detection and handling of

  9. General strongly nonlinear variational inequalities

    International Nuclear Information System (INIS)

    Siddiqi, A.H.; Ansari, Q.H.

    1990-07-01

    In this paper we develop iterative algorithms for finding approximate solutions for new classes of variational and quasi-variational inequalities which include, as special case, some known results in this field. It is shown that the solutions of the iterative schemes converge to the exact solutions. (author). 15 refs

  10. Comparing variation across European countries

    DEFF Research Database (Denmark)

    Thygesen, Lau C; Baixauli-Pérez, Cristobal; Librero-López, Julián

    2015-01-01

    BACKGROUND: In geographical studies, population distribution is a key issue. An unequal distribution across units of analysis might entail extra-variation and produce misleading conclusions on healthcare performance variations. This article aims at assessing the impact of building more homogeneou...

  11. Strongly nonlinear parabolic variational inequalities.

    Science.gov (United States)

    Browder, F E; Brézis, H

    1980-02-01

    An existence and uniqueness result is established for a general class of variational inequalities for parabolic partial differential equations of the form partial differentialu/ partial differentialt + A(u) + g(u) = f with g nondecreasing but satisfying no growth condition. The proof is based upon a type of compactness result for solutions of variational inequalities that should find a variety of other applications.

  12. Time variations in geomagnetic intensity

    Science.gov (United States)

    Valet, Jean-Pierre

    2003-03-01

    After many years spent by paleomagnetists studying the directional behavior of the Earth's magnetic field at all possible timescales, detailed measurements of field intensity are now needed to document the variations of the entire vector and to analyze the time evolution of the field components. A significant step has been achieved by combining intensity records derived from archeological materials and from lava flows in order to extract the global field changes over the past 12 kyr. A second significant step was due to the emergence of coherent records of relative paleointensity using the remanent magnetization of sediments to retrace the evolution of the dipole field. A third step was the juxtaposition of these signals with those derived from cosmogenic isotopes. Contemporaneous with the acquisition of records, new techniques have been developed to constrain the geomagnetic origin of the signals. Much activity has also been devoted to improving the quality of determinations of absolute paleointensity from volcanic rocks with new materials, proper selection of samples, and investigations of complex changes in magnetization during laboratory experiments. Altogether these developments brought us from a situation where the field changes were restricted to the past 40 kyr to the emergence of a coherent picture of the changes in the geomagnetic dipole moment for at least the past 1 Myr. On longer timescales the field variability and its average behavior is relatively well documented for the past 400 Myr. Section 3 gives a summary of most methods and techniques that are presently used to track the field intensity changes in the past. In each case, current limits and potential promises are discussed. The section 4 describes the field variations measured so far over various timescales covered by the archeomagnetic and the paleomagnetic records. Preference has always been given to composite records and databases in order to extract and discuss major and global geomagnetic

  13. On minimizers of causal variational principles

    International Nuclear Information System (INIS)

    Schiefeneder, Daniela

    2011-01-01

    Causal variational principles are a class of nonlinear minimization problems which arise in a formulation of relativistic quantum theory referred to as the fermionic projector approach. This thesis is devoted to a numerical and analytic study of the minimizers of a general class of causal variational principles. We begin with a numerical investigation of variational principles for the fermionic projector in discrete space-time. It is shown that for sufficiently many space-time points, the minimizing fermionic projector induces non-trivial causal relations on the space-time points. We then generalize the setting by introducing a class of causal variational principles for measures on a compact manifold. In our main result we prove under general assumptions that the support of a minimizing measure is either completely timelike, or it is singular in the sense that its interior is empty. In the examples of the circle, the sphere and certain flag manifolds, the general results are supplemented by a more detailed analysis of the minimizers. (orig.)

  14. Water quality, Multivariate statistical techniques, submarine out fall, spatial variation, temporal variation

    International Nuclear Information System (INIS)

    Garcia, Francisco; Palacio, Carlos; Garcia, Uriel

    2012-01-01

    Multivariate statistical techniques were used to investigate the temporal and spatial variations of water quality at the Santa Marta coastal area where a submarine out fall that discharges 1 m3/s of domestic wastewater is located. Two-way analysis of variance (ANOVA), cluster and principal component analysis and Krigging interpolation were considered for this report. Temporal variation showed two heterogeneous periods. From December to April, and July, where the concentration of the water quality parameters is higher; the rest of the year (May, June, August-November) were significantly lower. The spatial variation reported two areas where the water quality is different, this difference is related to the proximity to the submarine out fall discharge.

  15. Investigating Drama.

    Science.gov (United States)

    Pickering, Kenneth; And Others

    The purpose of this book is to provide an opportunity for investigating drama by a series of units, each of which examines an aspect of drama or theater. The 20 units discuss such topics as the definition of drama, dialogue in a poem by W. H. Auden, various aspects of the stage, improvisation, the visual impact of plays, "The Death of Grass" by…

  16. Variational approach to 68 Se

    International Nuclear Information System (INIS)

    Petrovici, A.; Schmid, K.W.; Faessler, A.; Baktash, C.; Shashi, P.

    1999-01-01

    For a unified description of the structure of medium mass proton-rich nuclei at low as well as high angular momenta we used the complex version of the Excited Vampir approach. We employed chains of variational calculations based on symmetry-projected essentially complex Hartree-Fock-Bogoliubov (HFB) vacua which include neutron-proton pairing and unnatural-parity correlations. Since the Vampir approaches allow the use of rather large model spaces and of general two-body interactions, large-scale nuclear structure studies going far beyond the abilities of the conventional shell-model configuration-mixing approach are possible. Furthermore, since these approaches provide detailed spectroscopic information for the lowest few states for each spin and parity, they also have considerable advantages with respect to the shell-model Monte Carlo method in which only expectation values of operators in the thermodynamic ensembles or the ground state can be calculated. Our previous investigations on microscopic aspects of shape coexistence in N∼Z nuclei in the A∼70 mass region indicated the presence of a strong competition between particular configurations based on large and small oblate and prolate quadrupole deformations. Furthermore, since in N = Z nuclei neutrons and protons fill the same single particle orbits, the isovector neutron-proton and the like-nucleon pairing correlations were found to be strongly competitive in even-even systems. In addition, the neutron and proton alignments with increasing angular momentum occur simultaneously in these nuclei. On the other hand the theoretical results suggest that certain properties of these nuclei are extremely sensitive to small variations of particular parts of the effective Hamiltonian. Thus, our results indicate that the oblate-prolate coexistence and mixing at low spins depend on the strengths of the neutron-proton T = 0 matrix elements involving nucleons occupying f 5/2 (f 7/2 ) and g 9/2 single particle orbits

  17. Observer variation in skeletal radiology

    Energy Technology Data Exchange (ETDEWEB)

    Cockshott, W.P.; Park, W.M.

    1983-08-01

    The factors that affect observer variation in bone radiology are analysed from data in the literature and on the basis of studies carried out at McMaster University on the hands and sacroiliac joints. A plea is made for presenting results in terms of Kappa statistics so that agreement due purely to chance is eliminated. In the conclusions the main variables that affect concordance are listed so that strategies can be developed to reduce observer variation. This is important in serial studies to ensure that the observer variations are smaller than the effect one wishes to measure.

  18. Seasonal variations of equatorial spread-F

    Directory of Open Access Journals (Sweden)

    B. V. Krishna Murthy

    Full Text Available The occurrence of spread-F at Trivandrum (8.5°N, 77°E, dip 0.5°N has been investigated on a seasonal basis in sunspot maximum and minimum years in terms of the growth rate of irregularities by the generalized collisional Rayleigh-Taylor (GRT instability mechanism which includes the gravitational and cross-field instability terms. The occurrence statistics of spread-F at Trivandrum have been obtained using quarter hourly ionograms. The nocturnal variations of the growth rate of irregularities by the GRT mechanism have been estimated for different seasons in sunspot maximum and minimum years at Trivandrum using h'F values and vertical drift velocities obtained from ionograms. It is found that the seasonal variation of spread-F occurrence at Trivandrum can, in general, be accounted for on the basis of the GRT mechanism.

  19. Seasonal variations of equatorial spread-F

    Directory of Open Access Journals (Sweden)

    K. S. V. Subbarao

    1994-01-01

    Full Text Available The occurrence of spread-F at Trivandrum (8.5°N, 77°E, dip 0.5°N has been investigated on a seasonal basis in sunspot maximum and minimum years in terms of the growth rate of irregularities by the generalized collisional Rayleigh-Taylor (GRT instability mechanism which includes the gravitational and cross-field instability terms. The occurrence statistics of spread-F at Trivandrum have been obtained using quarter hourly ionograms. The nocturnal variations of the growth rate of irregularities by the GRT mechanism have been estimated for different seasons in sunspot maximum and minimum years at Trivandrum using h'F values and vertical drift velocities obtained from ionograms. It is found that the seasonal variation of spread-F occurrence at Trivandrum can, in general, be accounted for on the basis of the GRT mechanism.

  20. Pulse pressure and diurnal blood pressure variation

    DEFF Research Database (Denmark)

    Knudsen, Søren Tang; Poulsen, Per Løgstrup; Hansen, Klavs Würgler

    2002-01-01

    retinopathy, nephropathy, macrovascular disease, PP, and diurnal BP variation in a group of type 2 diabetic patients. METHODS: In 80 type 2 diabetic patients we performed 24-h ambulatory BP (AMBP) and fundus photographs. Urinary albumin excretion was evaluated by urinary albumin/creatinine ratio. Presence...... or absence of macrovascular disease was assessed by an independent physician. RESULTS: Forty-nine patients had no detectable retinal changes (grade 1), 13 had grade 2 retinopathy, and 18 had more advanced retinopathy (grades 3-6). Compared to patients without retinopathy (grade 1), patients with grades 2......BACKGROUND: In nondiabetic subjects pulse pressure (PP) is an independent predictor of cardiovascular disease and microalbuminuria. Reduced circadian blood pressure (BP) variation is a potential risk factor for the development of diabetic complications. We investigated the association between...

  1. Seasonal variations of volcanic eruption frequencies

    Science.gov (United States)

    Stothers, Richard B.

    1989-01-01

    Do volcanic eruptions have a tendency to occur more frequently in the months of May and June? Some past evidence suggests that they do. The present study, based on the new eruption catalog of Simkin et al.(1981), investigates the monthly statistics of the largest eruptions, grouped according to explosive magnitude, geographical latitude, and year. At the 2-delta level, no month-to-month variations in eruption frequency are found to be statistically significant. Examination of previously published month-to-month variations suggests that they, too, are not statistically significant. It is concluded that volcanism, at least averaged over large portions of the globe, is probably not periodic on a seasonal or annual time scale.

  2. Clinical Investigation.

    Science.gov (United States)

    1979-09-30

    Zbylski, LaRossa, Cullington: A Simple Method of Rapid Assessment of Malar Depression . Annals of Plastic Surgery, Aug 79. Urology Service Fauver, H.E...J.R.: ST Depression Suggesting Subendocardial Ischemia in Neonates with PDA. Presented: Eighth Annual Army Association of Cardiok yy tt,eting, Tacoma...79/100 Investigation of the Tumor Reduction Effect of Combined Sodium-L-Ascorbate and 5FU Chemotherapy in Transplanted B16 Melanoma of Mice. (O

  3. Paleosecular variations from lake sediments

    International Nuclear Information System (INIS)

    Lund, S.P.; Banerjee, S.K.

    1979-01-01

    Data are presented on the secular variations of the magnetization of wet and dry lake sediments for 17 North American locations. The usefullness of this data in terms of the geomagnetic field is discussed

  4. Explaining variation in nascent entrepreneurship

    NARCIS (Netherlands)

    A.J. van Stel (André); A.R.M. Wennekers (Sander); P. Reynolds (Paul); A.R. Thurik (Roy)

    2004-01-01

    textabstractThis paper aims at explaining cross-country variation in nascent entrepreneurship. Regression analysis is applied using various explanatory variables derived from three different approaches. We make use of the Global Entrepreneurship Monitor database, including nascent entrepreneurship

  5. Thematic Composition and Idiom Variation

    Directory of Open Access Journals (Sweden)

    Cserép Attila

    2017-11-01

    Full Text Available The Corpus of Contemporary American English (COCA has been studied to retrieve variant forms of semantically decomposable idioms that have no thematic composition for the purpose of determining whether thematic composition is a necessary criterion for idiom variation as claimed by Horn (2003. The syntactic variants searched for include passive, raising, tough-movement, relative clauses and wh-questions. Horn’s (2003 hypothesis is not fully confirmed, as some variation has been found.

  6. A compiler for variational forms

    OpenAIRE

    Kirby, Robert C.; Logg, Anders

    2011-01-01

    As a key step towards a complete automation of the finite element method, we present a new algorithm for automatic and efficient evaluation of multilinear variational forms. The algorithm has been implemented in the form of a compiler, the FEniCS Form Compiler FFC. We present benchmark results for a series of standard variational forms, including the incompressible Navier-Stokes equations and linear elasticity. The speedup compared to the standard quadrature-based approach is impressive; in s...

  7. Variational integrators for electric circuits

    International Nuclear Information System (INIS)

    Ober-Blöbaum, Sina; Tao, Molei; Cheng, Mulin; Owhadi, Houman; Marsden, Jerrold E.

    2013-01-01

    In this contribution, we develop a variational integrator for the simulation of (stochastic and multiscale) electric circuits. When considering the dynamics of an electric circuit, one is faced with three special situations: 1. The system involves external (control) forcing through external (controlled) voltage sources and resistors. 2. The system is constrained via the Kirchhoff current (KCL) and voltage laws (KVL). 3. The Lagrangian is degenerate. Based on a geometric setting, an appropriate variational formulation is presented to model the circuit from which the equations of motion are derived. A time-discrete variational formulation provides an iteration scheme for the simulation of the electric circuit. Dependent on the discretization, the intrinsic degeneracy of the system can be canceled for the discrete variational scheme. In this way, a variational integrator is constructed that gains several advantages compared to standard integration tools for circuits; in particular, a comparison to BDF methods (which are usually the method of choice for the simulation of electric circuits) shows that even for simple LCR circuits, a better energy behavior and frequency spectrum preservation can be observed using the developed variational integrator

  8. Variational model for one-dimensional quantum magnets

    Science.gov (United States)

    Kudasov, Yu. B.; Kozabaranov, R. V.

    2018-04-01

    A new variational technique for investigation of the ground state and correlation functions in 1D quantum magnets is proposed. A spin Hamiltonian is reduced to a fermionic representation by the Jordan-Wigner transformation. The ground state is described by a new non-local trial wave function, and the total energy is calculated in an analytic form as a function of two variational parameters. This approach is demonstrated with an example of the XXZ-chain of spin-1/2 under a staggered magnetic field. Generalizations and applications of the variational technique for low-dimensional magnetic systems are discussed.

  9. Continuous radon measurements in schools: time variations and related parameters

    International Nuclear Information System (INIS)

    Giovani, C.; Cappelletto, C.; Garavaglia, M.; Pividore, S.; Villalta, R.

    2004-01-01

    Some results are reported of observations made within a four-year survey, during different seasons and in different conditions of school building use. Natural radon variations (day-night cycles, seasonal and temperature dependent variations etc..) and artificial ones (opening of windows, weekends and vacations, deployment of air conditioning or heating systems. etc.) were investigated as parameters affecting time dependent radon concentrations. (P.A.)

  10. Planck intermediate results XXIV. Constraints on variations in fundamental constants

    DEFF Research Database (Denmark)

    Ade, P. A. R.; Aghanim, N.; Arnaud, M.

    2015-01-01

    cosmological probes. We conclude that independent time variations of the fine structure constant and of the mass of the electron are constrained by Planck to Δ Α/Α = (3.6±3.7) x 10-3 and Δ me/me = (4 ±11) x 10-3 at the 68% confidence level. We also investigate the possibility of a spatial variation of the fine...

  11. Is there much variation in variation? Revisiting statistics of small area variation in health services research

    Directory of Open Access Journals (Sweden)

    Ibáñez Berta

    2009-04-01

    Full Text Available Abstract Background The importance of Small Area Variation Analysis for policy-making contrasts with the scarcity of work on the validity of the statistics used in these studies. Our study aims at 1 determining whether variation in utilization rates between health areas is higher than would be expected by chance, 2 estimating the statistical power of the variation statistics; and 3 evaluating the ability of different statistics to compare the variability among different procedures regardless of their rates. Methods Parametric bootstrap techniques were used to derive the empirical distribution for each statistic under the hypothesis of homogeneity across areas. Non-parametric procedures were used to analyze the empirical distribution for the observed statistics and compare the results in six situations (low/medium/high utilization rates and low/high variability. A small scale simulation study was conducted to assess the capacity of each statistic to discriminate between different scenarios with different degrees of variation. Results Bootstrap techniques proved to be good at quantifying the difference between the null hypothesis and the variation observed in each situation, and to construct reliable tests and confidence intervals for each of the variation statistics analyzed. Although the good performance of Systematic Component of Variation (SCV, Empirical Bayes (EB statistic shows better behaviour under the null hypothesis, it is able to detect variability if present, it is not influenced by the procedure rate and it is best able to discriminate between different degrees of heterogeneity. Conclusion The EB statistics seems to be a good alternative to more conventional statistics used in small-area variation analysis in health service research because of its robustness.

  12. Existence of evolutionary variational solutions via the calculus of variations

    Science.gov (United States)

    Bögelein, Verena; Duzaar, Frank; Marcellini, Paolo

    In this paper we introduce a purely variational approach to time dependent problems, yielding the existence of global parabolic minimizers, that is ∫0T ∫Ω [uṡ∂tφ+f(x,Du)] dx dt⩽∫0T ∫Ω f(x,Du+Dφ) dx dt, whenever T>0 and φ∈C0∞(Ω×(0,T),RN). For the integrand f:Ω×R→[0,∞] we merely assume convexity with respect to the gradient variable and coercivity. These evolutionary variational solutions are obtained as limits of maps depending on space and time minimizing certain convex variational functionals. In the simplest situation, with some growth conditions on f, the method provides the existence of global weak solutions to Cauchy-Dirichlet problems of parabolic systems of the type ∂tu-divDξf(x,Du)=0 in Ω×(0,∞).

  13. Crosshole investigations

    International Nuclear Information System (INIS)

    Olsson, O.; Pihl, J.

    1987-09-01

    The analysis of the radar and seismic data has given a consistent description of the fracture zones at the Crosshole site in agreement with geological and other geophysical observations made in the boreholes. The hydraulic investigations within the Crosshole project have yielded substantial progress in assessing the hydrogeology of fractured granitic rocks. The crosshole hydraulic testing concentrated on measuring the distribution of hydraulic properties within the extensive fractured zones identified by geophysics. A new analysis involving the 'dimension' of the flow test has been developed to analyse the results of the crosshole sinusoidal testing. The combined analysis of the geophysical and the hydraulic data set has shown that groundwater flow is concentrated within a few major features which have been identified by the geophysical methods. (orig./DG)

  14. Laboratory investigations

    International Nuclear Information System (INIS)

    Handin, J.

    1980-01-01

    Our task is to design mined-repository systems that will adequately secure high-level nuclear waste for at least 10,000 yr and that will be mechanically stable for 50 to 100-yr periods of retrievability during which mistakes could be corrected and a valuable source of energy could be reclaimed, should national policy on the reprocessing of spent fuel ever change. The only credible path for the escape of radionuclides from the repository to the biosphere is through ground-water, and in hard rock, bulk permeability is largely governed by natural and artificial fracture systems. Catastrophic failure of an excavation in hard rock is likely to occur at the weakest links - the discontinuities in the rock mass that is perturbed first by mining and then by radiogenic heating. The laboratory can contribute precise measurements of the pertinent thermomechanical, hydrological and chemical properties and improve our understanding of the fundamental processes through careful experiments under well controlled conditions that simulate the prototype environment. Thus laboratory investigations are necessary, but they are not sufficient, for conventional sample sizes are small relative to natural defects like joints - i.e., the rock mass is not a continuum - and test durations are short compared to those that predictive modeling must take into account. Laboratory investigators can contribute substantially more useful data if they are provided facilities for testing large specimens(say one cubic meter) and for creep testing of all candidate host rocks. Even so, extrapolations of laboratory data to the field in neither space nor time are valid without the firm theoretical foundations yet to be built. Meanwhile in-situ measurements of structure-sensitive physical properties and access to direct observations of rock-mass character will be absolutely necessary

  15. Short period tidal variations of earth rotation

    Science.gov (United States)

    Yoder, C. F.; Williams, J. G.; Parke, M. E.; Dickey, J. O.

    1981-01-01

    It is explained that the tidal deformation of the earth's polar moment of inertia by the moon and sun cause periodic variations in rotation. The short period oscillations give rise to a meter-sized, diurnal signature in the lunar laser ranging data obtained at McDonald Observatory. A solution is given for the scale parameter k/C at fortnightly and monthly tidal frequencies. The results are compared with those obtained by other investigators and with a theoretical estimate which includes the effect of oceans and a decoupled fluid core.

  16. Variation of Natural Gamma Radiation in Isparta

    International Nuclear Information System (INIS)

    Akkurt, I.

    2004-01-01

    There is always a radiation in the earth, and its level is generated primarily by galactic cosmic rays (GCR), consisting of energetic nuclei of all naturally occurring elements, interacting with atmospheric constituents, through atomic and nuclear collisions. The other sources of natural radiations are global average background radiation from terrestrial sources such as soils, rocks ete. Background radiation levels in the atmosphere vary in intensity with latitude, altitude and phase of the solar cycle. Variation of natural radiation as a function of altitude, geological structure etc has been investigated. The measurements were performed using portable radiation counter which connected to NaI(Tl) probe

  17. Total Variation Depth for Functional Data

    KAUST Repository

    Huang, Huang

    2016-11-15

    There has been extensive work on data depth-based methods for robust multivariate data analysis. Recent developments have moved to infinite-dimensional objects such as functional data. In this work, we propose a new notion of depth, the total variation depth, for functional data. As a measure of depth, its properties are studied theoretically, and the associated outlier detection performance is investigated through simulations. Compared to magnitude outliers, shape outliers are often masked among the rest of samples and harder to identify. We show that the proposed total variation depth has many desirable features and is well suited for outlier detection. In particular, we propose to decompose the total variation depth into two components that are associated with shape and magnitude outlyingness, respectively. This decomposition allows us to develop an effective procedure for outlier detection and useful visualization tools, while naturally accounting for the correlation in functional data. Finally, the proposed methodology is demonstrated using real datasets of curves, images, and video frames.

  18. Light Curve Variations of AR Lacertae

    Directory of Open Access Journals (Sweden)

    Il-Seong Nha

    1991-12-01

    Full Text Available Sixteen unitary Light curves of AR Lac in B and V are made at Yonsei University Observatory in the period of 1980-1988. Some overview findings of light variations are made. (1 The light variations outside eclipse follow none of the wave migration patterns reported by previous investigators. (2 Complicated shapes outside eclipse are apparently much reduced in the light curves of 1983-1984. This suggests that, in the future, AR Lac has a chance to attain a normal state with mo complicated interactions. (3 The depths of the primary and the secondary mid-eclipses are changing year-to-year. (4 The K0 star, the larger component, has brightened by 0.m14 V, while the G2 star has shown a fluctuation of about 0.m05 in V. (5 The B-V values at primary mid-eclipse have no correlation with the depth variations. (6 Independently of the increase of maximum brightness, the B-V colors in the non-eclipsed phases changed slightly over the years.

  19. Variation in prescribing for anxiety and depression: a reflection of health inequalities, cultural differences or variations in access to care?

    OpenAIRE

    Peters Jean; Grimsley Michael; Dibben Chris; Goyder Elizabeth; Blank Lindsay; Ellis Elizabeth

    2006-01-01

    Abstract Background There are large variations in mental health prescribing in UK populations. However the underlying reasons for these differences, which may be related to differences in prevalence, cultural expectations or practical difficulties in access to treatment, remain uncertain. Methods Linear modelling was used to investigate whether population characteristics or access to primary care account for variations in mental health prescribing across 39 deprived neighbourhoods. Results Th...

  20. Seasonal variation in sports participation.

    Science.gov (United States)

    Schüttoff, Ute; Pawlowski, Tim

    2018-02-01

    This study explores indicators describing socio-demographics, sports participation characteristics and motives which are associated with variation in sports participation across seasons. Data were drawn from the German Socio-Economic Panel which contains detailed information on the sports behaviour of adults in Germany. Overall, two different measures of seasonal variation are developed and used as dependent variables in our regression models. The first variable measures the coefficient of (seasonal) variation in sport-related energy expenditure per week. The second variable measures whether activity drops below the threshold as defined by the World Health Organization (WHO). Results suggest that the organisational setting, the intensity and number of sports practised, and the motive for participation are strongly correlated with the variation measures used. For example, both, participation in a sports club and a commercial facility, are associated with reduced seasonal variation and a significantly higher probability of participating at a volume above the WHO threshold across all seasons. These findings give some impetus for policymaking and the planning of sports programmes as well as future research directions.

  1. Understanding human DNA sequence variation.

    Science.gov (United States)

    Kidd, K K; Pakstis, A J; Speed, W C; Kidd, J R

    2004-01-01

    Over the past century researchers have identified normal genetic variation and studied that variation in diverse human populations to determine the amounts and distributions of that variation. That information is being used to develop an understanding of the demographic histories of the different populations and the species as a whole, among other studies. With the advent of DNA-based markers in the last quarter century, these studies have accelerated. One of the challenges for the next century is to understand that variation. One component of that understanding will be population genetics. We present here examples of many of the ways these new data can be analyzed from a population perspective using results from our laboratory on multiple individual DNA-based polymorphisms, many clustered in haplotypes, studied in multiple populations representing all major geographic regions of the world. These data support an "out of Africa" hypothesis for human dispersal around the world and begin to refine the understanding of population structures and genetic relationships. We are also developing baseline information against which we can compare findings at different loci to aid in the identification of loci subject, now and in the past, to selection (directional or balancing). We do not yet have a comprehensive understanding of the extensive variation in the human genome, but some of that understanding is coming from population genetics.

  2. Normal variation of hepatic artery

    International Nuclear Information System (INIS)

    Kim, Inn; Nam, Myung Hyun; Rhim, Hyun Chul; Koh, Byung Hee; Seo, Heung Suk; Kim, Soon Yong

    1987-01-01

    This study was an analyses of blood supply of the liver in 125 patients who received hepatic arteriography and abdominal aortography from Jan. 1984 to Dec. 1986 at the Department of Radiology of Hanyang University Hospital. A. Variations in extrahepatic arteries: 1. The normal extrahepatic artery pattern occurred in 106 of 125 cases (84.8%) ; Right hepatic and left hepatic arteries arising from the hepatic artery proper and hepatic artery proper arising from the common hepatic artery. 2. The most common type of variation of extrahepatic artery was replaced right hepatic artery from superior mesenteric artery: 6 of 125 cases (4.8%). B. Variations in intrahepatic arteries: 1. The normal intrahepatic artery pattern occurred in 83 of 125 cases (66.4%). Right hepatic and left hepatic arteries arising from the hepatic artery proper and middle hepatic artery arising from lower portion of the umbilical point of left hepatic artery. 2. The most common variation of intrahepatic arteries was middle hepatic artery. 3. Among the variation of middle hepatic artery; Right, middle and left hepatic arteries arising from the same location at the hepatic artery proper was the most common type; 17 of 125 cases (13.6%)

  3. Geographic variation in gorilla limb bones.

    Science.gov (United States)

    Jabbour, Rebecca S; Pearman, Tessa L

    2016-06-01

    Gorilla systematics has received increased attention over recent decades from primatologists, conservationists, and paleontologists. Studies of geographic variation in DNA, skulls, and teeth have led to new taxonomic proposals, such as recognition of two gorilla species, Gorilla gorilla (western gorilla) and Gorilla beringei (eastern gorilla). Postcranial differences between mountain gorillas (G. beringei beringei) and western lowland gorillas (G. g. gorilla) have a long history of study, but differences between the limb bones of the eastern and western species have not yet been examined with an emphasis on geographic variation within each species. In addition, proposals for recognition of the Cross River gorilla as Gorilla gorilla diehli and gorillas from Tshiaberimu and Kahuzi as G. b. rex-pymaeorum have not been evaluated in the context of geographic variation in the forelimb and hindlimb skeletons. Forty-three linear measurements were collected from limb bones of 266 adult gorillas representing populations of G. b. beringei, Gorilla beringei graueri, G. g. gorilla, and G. g. diehli in order to investigate geographic diversity. Skeletal elements included the humerus, radius, third metacarpal, third proximal hand phalanx, femur, tibia, calcaneus, first metatarsal, third metatarsal, and third proximal foot phalanx. Comparisons of means and principal components analyses clearly differentiate eastern and western gorillas, indicating that eastern gorillas have absolutely and relatively smaller hands and feet, among other differences. Gorilla subspecies and populations cluster consistently by species, although G. g. diehli may be similar to the eastern gorillas in having small hands and feet. The subspecies of G. beringei are distinguished less strongly and by different variables than the two gorilla species. Populations of G. b. graueri are variable, and Kahuzi and Tshiaberimu specimens do not cluster together. Results support the possible influence of

  4. Variational principles for nonpotential operators

    CERN Document Server

    Filippov, V M

    1989-01-01

    This book develops a variational method for solving linear equations with B-symmetric and B-positive operators and generalizes the method to nonlinear equations with nonpotential operators. The author carries out a constructive extension of the variational method to "nonvariational" equations (including parabolic equations) in classes of functionals which differ from the Euler-Lagrange functionals. In this connection, some new functions spaces are considered. Intended for mathematicians working in the areas of functional analysis and differential equations, this book would also prove useful for researchers in other areas and students in advanced courses who use variational methods in solving linear and nonlinear boundary value problems in continuum mechanics and theoretical physics.

  5. Solid mechanics a variational approach

    CERN Document Server

    Dym, Clive L

    2013-01-01

    Solid Mechanics: A Variational Approach, Augmented Edition presents a lucid and thoroughly developed approach to solid mechanics for students engaged in the study of elastic structures not seen in other texts currently on the market. This work offers a clear and carefully prepared exposition of variational techniques as they are applied to solid mechanics. Unlike other books in this field, Dym and Shames treat all the necessary theory needed for the study of solid mechanics and include extensive applications. Of particular note is the variational approach used in developing consistent structural theories and in obtaining exact and approximate solutions for many problems.  Based on both semester and year-long courses taught to undergraduate seniors and graduate students, this text is geared for programs in aeronautical, civil, and mechanical engineering, and in engineering science. The authors’ objective is two-fold: first, to introduce the student to the theory of structures (one- and two-dimensional) as ...

  6. Variational methods in molecular modeling

    CERN Document Server

    2017-01-01

    This book presents tutorial overviews for many applications of variational methods to molecular modeling. Topics discussed include the Gibbs-Bogoliubov-Feynman variational principle, square-gradient models, classical density functional theories, self-consistent-field theories, phase-field methods, Ginzburg-Landau and Helfrich-type phenomenological models, dynamical density functional theory, and variational Monte Carlo methods. Illustrative examples are given to facilitate understanding of the basic concepts and quantitative prediction of the properties and rich behavior of diverse many-body systems ranging from inhomogeneous fluids, electrolytes and ionic liquids in micropores, colloidal dispersions, liquid crystals, polymer blends, lipid membranes, microemulsions, magnetic materials and high-temperature superconductors. All chapters are written by leading experts in the field and illustrated with tutorial examples for their practical applications to specific subjects. With emphasis placed on physical unders...

  7. Lexical Variation and Change in British Sign Language

    Science.gov (United States)

    Stamp, Rose; Schembri, Adam; Fenlon, Jordan; Rentelis, Ramas; Woll, Bencie; Cormier, Kearsy

    2014-01-01

    This paper presents results from a corpus-based study investigating lexical variation in BSL. An earlier study investigating variation in BSL numeral signs found that younger signers were using a decreasing variety of regionally distinct variants, suggesting that levelling may be taking place. Here, we report findings from a larger investigation looking at regional lexical variants for colours, countries, numbers and UK placenames elicited as part of the BSL Corpus Project. Age, school location and language background were significant predictors of lexical variation, with younger signers using a more levelled variety. This change appears to be happening faster in particular sub-groups of the deaf community (e.g., signers from hearing families). Also, we find that for the names of some UK cities, signers from outside the region use a different sign than those who live in the region. PMID:24759673

  8. Structure variations of carbonizing lignin

    International Nuclear Information System (INIS)

    Otani, C.; Polidoro, H.A.; Otani, S.; Craievich, A.F.

    1984-01-01

    The studied lignin is a by-product of the process of ethanol production from eucaliptus. It was heat-treated under inert atmosphere conditions at increasing temperatures from 300C up to 2400C. The structural variations were studied by wide-angle X-ray diffraction, small-angle X-ray scattering and infrared absorption spectroscopy. The bulk and 'real' density of the compacted materials have also been determined as functions of the final temperature. These experimental results enabled us to establish a mechanism of structure variation based on the formation of a turbostratic graphite-like and porous structure within the initially amorphous lignin matrix. (Author) [pt

  9. Variational principle in quantum mechanics

    International Nuclear Information System (INIS)

    Popiez, L.

    1986-01-01

    The variational principle in a standard, path integral formulation of quantum mechanics (as proposed by Dirac and Feynman) appears only in the context of a classical limit n to 0 and manifests itself through the method of abstract stationary phase. Symbolically it means that a probability amplitude averaged over trajectories denotes a classical evolution operator for points in a configuration space. There exists, however, the formulation of quantum dynamics in which variational priniple is one of basic postulates. It is explained that the translation between stochastic and quantum mechanics in this case can be understood as in Nelson's stochastic mechanics

  10. A survey of variational principles

    International Nuclear Information System (INIS)

    Lewins, J.D.

    1993-01-01

    The survey of variational principles has ranged widely from its starting point in the Lagrange multiplier to optimisation principles. In an age of digital computation, these classic methods can be adapted to improve such calculations. We emphasize particularly the advantage of basing finite element methods on variational principles, especially if, as maximum and minimum principles, these can provide bounds and hence estimates of accuracy. The non-symmetric (and hence stationary rather than extremum principles) are seen however to play a significant role in optimisation theory. (Orig./A.B.)

  11. Circadian variation in sports performance.

    Science.gov (United States)

    Atkinson, G; Reilly, T

    1996-04-01

    Chronobiology is the science concerned with investigations of time-dependent changes in physiological variables. Circadian rhythms refer to variations that recur every 24 hours. Many physiological circadian rhythms at rest are endogenously controlled, and persist when an individual is isolated from environmental fluctuations. Unlike physiological variables, human performance cannot be monitored continuously in order to describe circadian rhythmicity. Experimental studies of the effect of circadian rhythms on performance need to be carefully designed in order to control for serial fatigue effects and to minimise disturbances in sleep. The detection of rhythmicity in performance variables is also highly influenced by the degree of test-retest repeatability of the measuring equipment. The majority of components of sports performance, e.g. flexibility, muscle strength, short term high power output, vary with time of day in a sinusoidal manner and peak in the early evening close to the daily maximum in body temperature. Psychological tests of short term memory, heart rate-based tests of physical fitness, and prolonged submaximal exercise performance carried out in hot conditions show peak times in the morning. Heart rate-based tests of work capacity appear to peak in the morning because the heart rate responses to exercise are minimal at this time of day. Post-lunch declines are evident with performance variables such as muscle strength, especially if measured frequently enough and sequentially within a 24-hour period to cause fatigue in individuals. More research work is needed to ascertain whether performance in tasks demanding fine motor control varies with time of day. Metabolic and respiratory rhythms are flattened when exercise becomes strenuous whilst the body temperature rhythm persists during maximal exercise. Higher work-rates are selected spontaneously in the early evening. At present, it is not known whether time of day influences the responses of a set

  12. Seasonal variations in sleep disorders of nurses.

    Science.gov (United States)

    Chang, Yuanmay; Lam, Calvin; Chen, Su-Ru; Sithole, Trevor; Chung, Min-Huey

    2017-04-01

    To investigate the difference between nurses and the general population regarding seasonal variations in sleep disorders during 2004-2008. The effects of season and group interaction on sleep disorders with regard to different comorbidities were also examined. Studies on seasonal variations in sleep disorders were mainly conducted in Norway for the general population. Furthermore, whether different comorbidities cause seasonal variations in sleep disorders in nurses remains unknown. A retrospective study. Data from the Taiwan National Health Insurance Research Database were used in generalised estimating equation Poisson distribution models to investigate the differences in sleep disorders between nurses and the general population diagnosed with sleep disorders (each n = 7643) as well as the interaction effects of sleep disorders between the groups with respect to different seasons. Furthermore, the interaction effects between groups and seasons on sleep disorders in the subgroups of comorbid anxiety disorders and depressive disorders were studied. Both the nurses and the general population had fewer outpatient visits for sleep disorders in winter than in other seasons. The nurses had fewer outpatient visits for sleep disorders than the general population did in each season. The nurses had more outpatient visits for sleep disorders in winter than in summer compared with the general population in the comorbid depressive disorder subgroup but not in the comorbid anxiety disorder subgroup. Nurses and the general population exhibited similar seasonal patterns of sleep disorders, but nurses had fewer outpatient visits for sleep disorders than the general population did in each season. For nurses with comorbid depressive disorders, outpatient visits for sleep disorders were more numerous in winter than in summer, potentially because nurses with comorbid depressive disorders are affected by shorter daylight exposure during winter. Depression and daylight exposure may

  13. Epigenetic variation during the adult lifespan

    DEFF Research Database (Denmark)

    Talens, Rudolf P; Christensen, Kaare; Putter, Hein

    2012-01-01

    The accumulation of epigenetic changes was proposed to contribute to the age-related increase in the risk of most common diseases. In this study on 230 monozygotic twin pairs (MZ pairs), aged 18-89 years, we investigated the occurrence of epigenetic changes over the adult lifespan. Using mass...... individuals, ranging from 1.2-fold larger at ABCA1 (P = 0.010) to 1.6-fold larger at INS (P = 3.7 × 10(-07) ). Similarly, there was more within-MZ-pair discordance in old as compared with young MZ pairs, except for GNASAS, ranging from an 8% increase in discordance each decade at CRH (P = 8.9 × 10...... spectrometry, we investigated variation in global (LINE1) DNA methylation and in DNA methylation at INS, KCNQ1OT1, IGF2, GNASAS, ABCA1, LEP, and CRH, candidate loci for common diseases. Except for KCNQ1OT1, interindividual variation in locus-specific DNA methylation was larger in old individuals than in young...

  14. Variational linear algebraic equations method

    International Nuclear Information System (INIS)

    Moiseiwitsch, B.L.

    1982-01-01

    A modification of the linear algebraic equations method is described which ensures a variational bound on the phaseshifts for potentials having a definite sign at all points. The method is illustrated by the elastic scattering of s-wave electrons by the static field of atomic hydrogen. (author)

  15. Visualization of Variation and Variability

    NARCIS (Netherlands)

    Busking, S.

    2014-01-01

    As datasets grow in size and complexity, the importance of comparison as a tool for analysis is growing. We define comparison as the act of analyzing variation or variability based on two or more specific instances of the data. This thesis explores a number of cases spread across the range of

  16. Regularization of Nonmonotone Variational Inequalities

    International Nuclear Information System (INIS)

    Konnov, Igor V.; Ali, M.S.S.; Mazurkevich, E.O.

    2006-01-01

    In this paper we extend the Tikhonov-Browder regularization scheme from monotone to rather a general class of nonmonotone multivalued variational inequalities. We show that their convergence conditions hold for some classes of perfectly and nonperfectly competitive economic equilibrium problems

  17. Sea level and climate variations

    NARCIS (Netherlands)

    Oerlemans, J.

    1985-01-01

    Review paper, ESA Symposium on Application of Satellite Data to Climate Modelling. Alpbach (Austria) Sea level is an essential component of the climate system, on which many human activities in the coastal zone depend. Climate variations leading to changes in relative sea level are

  18. On quadratic variation of martingales

    Indian Academy of Sciences (India)

    On quadratic variation of martingales. 459. The proof relied on the theory of stochastic integration. Subsequently, in Karandikar. [4], the formula was derived using only Doob's maximal inequality. Thus this could be the starting point for the development of stochastic calculus for continuous semimartingales without bringing in ...

  19. Evolutionary significance of epigenetic variation

    NARCIS (Netherlands)

    Richards, C.L.; Verhoeven, K.J.F.; Bossdorf, O.; Wendel, J.F.; Greilhuber, J.; Dolezel, J.; Leitch, I.J.

    2012-01-01

    Several chapters in this volume demonstrate how epigenetic work at the molecular level over the last few decades has revolutionized our understanding of genome function and developmental biology. However, epigenetic processes not only further our understanding of variation and regulation at the

  20. Genetisk variation og langt liv

    DEFF Research Database (Denmark)

    Sørensen, Mette

    2013-01-01

    andre ikke gør. I dette ph.d.-projekt undersøgte vi sammenhængen mellem levetid og variation i tre biologiske skadesprocesser. De tre er: antioxidanter, væksthormon/insulin-signalering og DNA-reparation. Vi fandt nye genvariationer, hvoraf nogle har positiv indflydelse på chancen for at blive meget...

  1. Linking numbers and variational method

    International Nuclear Information System (INIS)

    Oda, I.; Yahikozawa, S.

    1989-09-01

    The ordinary and generalized linking numbers for two surfaces of dimension p and n-p-1 in an n dimensional manifold are derived. We use a variational method based on the properties of topological quantum field theory in order to derive them. (author). 13 refs, 2 figs

  2. Spatial variation in messaging effects

    Science.gov (United States)

    Warshaw, Christopher

    2018-05-01

    There is large geographic variation in the public's views about climate change in the United States. Research now shows that climate messages can influence public beliefs about the scientific consensus on climate change, particularly in the places that are initially more skeptical.

  3. Comparison of respiratory-induced variations in photoplethysmographic signals

    International Nuclear Information System (INIS)

    Li, Jin; Jin, Jie; Chen, Xiang; Sun, Weixin; Guo, Ping

    2010-01-01

    Photoplethysmography (PPG) is an optical method for detecting blood volume changes in tissue. Respiratory-induced intensity, frequency and amplitude variations are contained in the PPG signal; thus, an understanding of the relationships between all of these variations and respiration is essential to advancing respiration monitoring based on PPG. This study investigated correlations between respiratory-induced variations extracted from PPG and simultaneous respiratory signals. PPG signals were recorded from 28 healthy subjects under eight different conditions. Six respiratory-induced variations, i.e. the period of the systole, diastole and pulse, the amplitude of the systole and diastole, and the intensity variation, were determined from the PPG signal. The results indicate that, compared with the period of the pulse, the period of the systole and diastole correlates weakly with respiration; the amplitude of the diastole has a stronger correlation with respiration than the amplitude of the systole. For men, when the respiratory rate is less than 10 breaths min −1 , the period of the pulse has the strongest correlation with respiration, whereas up to or above 15 breaths min −1 , the intensity variation becomes strongest in the sitting posture, while the amplitude of the diastole is strongest in the supine posture. For women, compared with the other variations, the period of the pulse has nearly the strongest correlation with respiration, independent of respiratory rate or posture

  4. Variational integrators in plasma physics

    Energy Technology Data Exchange (ETDEWEB)

    Kraus, Michael

    2013-07-01

    To a large extent, research in plasma physics is concerned with the description and analysis of energy and momentum transfer between different scales and different kinds of waves. In the numerical modelling of such phenomena it appears to be crucial to describe the transfer processes preserving the underlying conservation laws in order to prevent physically spurious solutions. In this work, special numerical methods, so called variational integrators, are developed for several models of plasma physics. Special attention is given to conservation properties like conservation of energy and momentum. By design, variational integrators are applicable to all systems that have a Lagrangian formulation. Usually, equations of motion are derived by Hamilton's action principle and then discretised. In the application of the variational integrator theory, the order of these steps is reversed. At first, the Lagrangian and the accompanying variational principle are discretised, such that discrete equations of motion can be obtained directly by applying the discrete variational principle to the discrete Lagrangian. The advantage of this approach is that the resulting discretisation automatically retains the conservation properties of the continuous system. Following an overview of the geometric formulation of classical mechanics and field theory, which forms the basis of the variational integrator theory, variational integrators are introduced in a framework adapted to problems from plasma physics. The applicability of variational integrators is explored for several important models of plasma physics: particle dynamics (guiding centre dynamics), kinetic theory (the Vlasov-Poisson system) and fluid theory (magnetohydrodynamics). These systems, with the exception of guiding centre dynamics, do not possess a Lagrangian formulation to which the variational integrator methodology is directly applicable. Therefore the theory is extended by linking it to Ibragimov's theory of

  5. Variational integrators in plasma physics

    International Nuclear Information System (INIS)

    Kraus, Michael

    2013-01-01

    To a large extent, research in plasma physics is concerned with the description and analysis of energy and momentum transfer between different scales and different kinds of waves. In the numerical modelling of such phenomena it appears to be crucial to describe the transfer processes preserving the underlying conservation laws in order to prevent physically spurious solutions. In this work, special numerical methods, so called variational integrators, are developed for several models of plasma physics. Special attention is given to conservation properties like conservation of energy and momentum. By design, variational integrators are applicable to all systems that have a Lagrangian formulation. Usually, equations of motion are derived by Hamilton's action principle and then discretised. In the application of the variational integrator theory, the order of these steps is reversed. At first, the Lagrangian and the accompanying variational principle are discretised, such that discrete equations of motion can be obtained directly by applying the discrete variational principle to the discrete Lagrangian. The advantage of this approach is that the resulting discretisation automatically retains the conservation properties of the continuous system. Following an overview of the geometric formulation of classical mechanics and field theory, which forms the basis of the variational integrator theory, variational integrators are introduced in a framework adapted to problems from plasma physics. The applicability of variational integrators is explored for several important models of plasma physics: particle dynamics (guiding centre dynamics), kinetic theory (the Vlasov-Poisson system) and fluid theory (magnetohydrodynamics). These systems, with the exception of guiding centre dynamics, do not possess a Lagrangian formulation to which the variational integrator methodology is directly applicable. Therefore the theory is extended by linking it to Ibragimov's theory of

  6. Genomic variation in Salmonella enterica core genes for epidemiological typing

    DEFF Research Database (Denmark)

    Leekitcharoenphon, Pimlapas; Lukjancenko, Oksana; Rundsten, Carsten Friis

    2012-01-01

    Background: Technological advances in high throughput genome sequencing are making whole genome sequencing (WGS) available as a routine tool for bacterial typing. Standardized procedures for identification of relevant genes and of variation are needed to enable comparison between studies and over...... genomes and evaluate their value as typing targets, comparing whole genome typing and traditional methods such as 16S and MLST. A consensus tree based on variation of core genes gives much better resolution than 16S and MLST; the pan-genome family tree is similar to the consensus tree, but with higher...... that there is a positive selection towards mutations leading to amino acid changes. Conclusions: Genomic variation within the core genome is useful for investigating molecular evolution and providing candidate genes for bacterial genome typing. Identification of genes with different degrees of variation is important...

  7. Nuclear level density variation with angular momentum induced shape transition

    International Nuclear Information System (INIS)

    Aggarwal, Mamta

    2016-01-01

    Variation of Nuclear level density (NLD) with the excitation energy and angular momentum in particular has been a topic of interest in the recent past and there have been continuous efforts in this direction on the theoretical and experimental fronts but a conclusive trend in the variation of nuclear level density parameter with angular momentum has not been achieved so far. A comprehensive investigation of N=68 isotones around the compound nucleus 119 Sb from neutron rich 112 Ru (Z=44) to neutron deficient 127 Pr (Z= 59) nuclei is presented to understand the angular momentum induced variations in inverse level density parameter and the possible influence of deformation and structural transitions on the variations on NLd

  8. Model of Dipole Field Variations in the LEP Bending Magnets

    CERN Document Server

    Bravin, Enrico; Drees, A; Mugnai, G

    1998-01-01

    The determination of the Z mass at LEP requires a knowledge of the relative beam energy in the order of 10 ppm, therefore it is essential to understand the dipole field variations to the same level of accuracy. In LEP the bending magnet field shows a relative increase of the order of 100 ppm over 10 hours, which was found to be caused by leakage currents from railways flowing along the vacuum cham ber and temperature variations. A LEP dipole test bench was set up for systematic investigations. Field variations were monitored with NMR probes while the cooling water temperature of both coil and vacuum chamber was kept under control. The results lead to a parametrisation of the magnetic field variation as a function of the vacuum chamber current and temperature.

  9. Y-Chromosome variation in hominids: intraspecific variation is limited to the polygamous chimpanzee.

    Directory of Open Access Journals (Sweden)

    Gabriele Greve

    Full Text Available BACKGROUND: We have previously demonstrated that the Y-specific ampliconic fertility genes DAZ (deleted in azoospermia and CDY (chromodomain protein Y varied with respect to copy number and position among chimpanzees (Pan troglodytes. In comparison, seven Y-chromosomal lineages of the bonobo (Pan paniscus, the chimpanzee's closest living relative, showed no variation. We extend our earlier comparative investigation to include an analysis of the intraspecific variation of these genes in gorillas (Gorilla gorilla and orangutans (Pongo pygmaeus, and examine the resulting patterns in the light of the species' markedly different social and mating behaviors. METHODOLOGY/PRINCIPAL FINDINGS: Fluorescence in situ hybridization analysis (FISH of DAZ and CDY in 12 Y-chromosomal lineages of western lowland gorilla (G. gorilla gorilla and a single lineage of the eastern lowland gorilla (G. beringei graueri showed no variation among lineages. Similar findings were noted for the 10 Y-chromosomal lineages examined in the Bornean orangutan (Pongo pygmaeus, and 11 Y-chromosomal lineages of the Sumatran orangutan (P. abelii. We validated the contrasting DAZ and CDY patterns using quantitative real-time polymerase chain reaction (qPCR in chimpanzee and bonobo. CONCLUSION/SIGNIFICANCE: High intraspecific variation in copy number and position of the DAZ and CDY genes is seen only in the chimpanzee. We hypothesize that this is best explained by sperm competition that results in the variant DAZ and CDY haplotypes detected in this species. In contrast, bonobos, gorillas and orangutans-species that are not subject to sperm competition-showed no intraspecific variation in DAZ and CDY suggesting that monoandry in gorillas, and preferential female mate choice in bonobos and orangutans, probably permitted the fixation of a single Y variant in each taxon. These data support the notion that the evolutionary history of a primate Y chromosome is not simply encrypted in its DNA

  10. General inverse problems for regular variation

    DEFF Research Database (Denmark)

    Damek, Ewa; Mikosch, Thomas Valentin; Rosinski, Jan

    2014-01-01

    Regular variation of distributional tails is known to be preserved by various linear transformations of some random structures. An inverse problem for regular variation aims at understanding whether the regular variation of a transformed random object is caused by regular variation of components ...

  11. Variation of Parameters in Differential Equations (A Variation in Making Sense of Variation of Parameters)

    Science.gov (United States)

    Quinn, Terry; Rai, Sanjay

    2012-01-01

    The method of variation of parameters can be found in most undergraduate textbooks on differential equations. The method leads to solutions of the non-homogeneous equation of the form y = u[subscript 1]y[subscript 1] + u[subscript 2]y[subscript 2], a sum of function products using solutions to the homogeneous equation y[subscript 1] and…

  12. Outdoor radon variation in Romania

    International Nuclear Information System (INIS)

    Simion, Elena; Simion, Florin

    2008-01-01

    Full text: The results of a long-term survey (1992 - 2006) of the variations of outdoor radon concentrations in semi-natural location from Romania are reported in the present paper. Measurements, covering between two and four sessions of the day (morning, afternoon, evening and night), were performed on a daily bases by 37 Environmental Radioactivity Monitoring Stations from National Environmental Radioactivity Survey Network. The method used was based on indirect determination of outdoor radon from aerosol samples collected on glass micro-fibre filters by drawing the air through the filters. The sampling was performed in a fixed place at a height of 2 m above the ground surface. Total beta counting of aerosol samples collected was performed immediately and after 20 hours. Values recorded during the years of continuous measurement indicated the presence of several patterns in the long-term variation of outdoor radon concentration: diurnal, seasonal and annual variation. For diurnal variation, outdoor radon concentration shows a maximum values in the night (early hours) and minimum values by day (in the afternoon). On average, this maximum is a factor of 2 higher than the minimum. Late autumn - beginning of winter maximum and an early spring minimum are characteristic for seasonal patterns. In the long term a seasonal pattern was observed for diurnal variation, with an average diurnal maximum to minimum ratio of 1.33 in winter compared with 3.0 in the summer months. The variations of outdoor radon levels showed little correlation with the uranium concentration of the ground and were attributed to changes in soil moisture content. In dry seasons, because of the low precipitation, the soil was drying out in the summer allowing fractures to develop and radon to migrate easily through the ground. Depending on micro-climatic and geological conditions, outdoor radon average concentrations in different regions of Romania are from 1200 mBq/mc to 13065 mBq/mc. The smallest

  13. Characteristics of seasonal variation and solar activity dependence of the geomagnetic solar quiet daily variation

    Science.gov (United States)

    Shinbori, A.; Koyama, Y.; Nose, M.; Hori, T.

    2017-12-01

    Characteristics of seasonal variation and solar activity dependence of the X- and Y-components of the geomagnetic solar quiet (Sq) daily variation at Memanbetsu in mid-latitudes and Guam near the equator have been investigated using long-term geomagnetic field data with 1-h time resolution from 1957 to 2016. In this analysis, we defined the quiet day when the maximum value of the Kp index is less than 3 for that day. In this analysis, we used the monthly average of the adjusted daily F10.7 corresponding to geomagnetically quiet days. For identification of the monthly mean Sq variation in the X and Y components (Sq-X and Sq-Y), we first determined the baseline of the X and Y components from the average value from 22 to 2 h (LT: local time) for each quiet day. Next, we calculated a deviation from the baseline of the X- and Y-components of the geomagnetic field for each quiet day, and computed the monthly mean value of the deviation for each local time. As a result, Sq-X and Sq-Y shows a clear seasonal variation and solar activity dependence. The amplitude of seasonal variation increases significantly during high solar activities, and is proportional to the solar F10.7 index. The pattern of the seasonal variation is quite different between Sq-X and Sq-Y. The result of the correlation analysis between the solar F10.7 index and Sq-X and Sq-Y shows almost the linear relationship, but the slope and intercept of the linear fitted line varies as function of local time and month. This implies that the sensitivity of Sq-X and Sq-Y to the solar activity is different for different local times and seasons. The local time dependence of the offset value of Sq-Y at Guam and its seasonal variation suggest a magnetic field produced by inter-hemispheric field-aligned currents (FACs). From the sign of the offset value of Sq-Y, it is infer that the inter-hemispheric FACs flow from the summer to winter hemispheres in the dawn and dusk sectors and from the winter to summer hemispheres in

  14. Environmental variation partitioned into separate heritable components

    DEFF Research Database (Denmark)

    Ørsted, Michael; Rohde, Palle Duun; Hoffmann, Ary A

    2018-01-01

    Trait variation is normally separated into genetic and environmental components, yet genetic factors also control the expression of environmental variation, encompassing plasticity across environmental gradients and within-environment responses. We defined four components of environmental variation......: plasticity across environments, variability in plasticity, variation within environments, and differences in within-environment variation across environments. We assessed these components for cold tolerance across five rearing temperatures using the Drosophila melanogaster Genetic Reference Panel (DGRP...

  15. Individual diet variation in a marine fish assemblage: Optimal Foraging Theory, Niche Variation Hypothesis and functional identity

    Science.gov (United States)

    Cachera, M.; Ernande, B.; Villanueva, M. C.; Lefebvre, S.

    2017-02-01

    Individual diet variation (i.e. diet variation among individuals) impacts intra- and inter-specific interactions. Investigating its sources and relationship with species trophic niche organization is important for understanding community structure and dynamics. Individual diet variation may increase with intra-specific phenotypic (or "individual state") variation and habitat variability, according to Optimal Foraging Theory (OFT), and with species trophic niche width, according to the Niche Variation Hypothesis (NVH). OFT proposes "proximate sources" of individual diet variation such as variations in habitat or size whereas NVH relies on "ultimate sources" related to the competitive balance between intra- and inter-specific competitions. The latter implies as a corollary that species trophic niche overlap, taken as inter-specific competition measure, decreases as species niche width and individual niche variation increase. We tested the complementary predictions of OFT and NVH in a marine fish assemblage using stomach content data and associated trophic niche metrics. The NVH predictions were tested between species of the assemblage and decomposed into a between- and a within-functional group component to assess the potential influence of species' ecological function. For most species, individual diet variation and niche overlap were consistently larger than expected. Individual diet variation increased with intra-specific variability in individual state and habitat, as expected from OFT. It also increased with species niche width but in compliance with the null expectation, thus not supporting the NVH. In contrast, species niche overlap increased significantly less than null expectation with both species niche width and individual diet variation, supporting NVH corollary. The between- and within-functional group components of the NVH relationships were consistent with those between species at the assemblage level. Changing the number of prey categories used to

  16. Ethnic variations in lung cancer.

    Science.gov (United States)

    Groeger, A M; Mueller, M R; Odocha, O; Dekan, G; Salat, A; Röthy, W; Esposito, V; Caputi, M; Wolner, E; Kaiser, H E

    1997-01-01

    Cancer of the lung is the most frequent cancer in the world, but with wide geographical variation in risk. It is most spread among males of all races worldwide, the only exception being its incidence among Chinese women aged 70 years and older. When comparing the different ethnic groups we have to consider that besides inhaling cigarette smoke actively or as a passive smoker the exposure to occupational carcinogens varies considerably according to different work places. In our study we compared 10 years of data from African-Americans in Howard University Hospital, Washington D.C. with 20 years of data from the white population in the University Hospital of Vienna, Austria. Ethnic patterns are generally consistent within each group in terms of both incidence and mortality. The difference in susceptibility between the sexes, the three major racial groups and already proven differences in genetic variations indicate the difference between individuals concerning the initiation and progression of lung cancer.

  17. Variational principles for dissipative waves

    Science.gov (United States)

    Dodin, I. Y.; Ruiz, D. E.

    2016-10-01

    Variational methods are a powerful tool in plasma theory. However, their applications are typically restricted to conservative systems or require doubling of variables, which often contradicts the purpose of the variational approach altogether. We show that these restrictions can be relaxed for some classes of dynamical systems that are of practical interest in plasma physics, particularly including dissipative plasma waves. Applications will be discussed to calculating dispersion relations and modulational dynamics of individual plasma waves and wave ensembles. The work was supported by the NNSA SSAA Program through DOE Research Grant No. DE-NA0002948, by the U.S. DOE through Contract No. DE-AC02-09CH11466, and by the U.S. DOD NDSEG Fellowship through Contract No. 32-CFR-168a.

  18. Periodic weather and climate variations

    International Nuclear Information System (INIS)

    Ivanov, Vladimir V

    2002-01-01

    Variations in meteorological parameters are largely due to periodic processes and can be forecast for several years. Many such processes are related to astronomical factors such as the gravitational influences of the Moon and the Sun, and the modulation of solar irradiance by lunar and planetary motion. The Moon, Jupiter, and Venus have the strongest effect. These influences produce lines in the spectra of meteorological variations, which are combinations of the harmonics of the frequencies of revolution of the planets, the Earth, and the Moon around the Sun with the harmonics of the lunar revolution around the Earth. Due to frequency differences between the orbital and radial motions, fine spectral features of three types appear: line splitting, line-profile complications due to radial oscillations, and additional lines due to the combination of radial-oscillation frequencies with perturbation harmonics. (reviews of topical problems)

  19. VARIATIONAL PRINCIPLE FOR PLANETARY INTERIORS

    International Nuclear Information System (INIS)

    Zeng, Li; Jacobsen, Stein B.

    2016-01-01

    In the past few years, the number of confirmed planets has grown above 2000. It is clear that they represent a diversity of structures not seen in our own solar system. In addition to very detailed interior modeling, it is valuable to have a simple analytical framework for describing planetary structures. The variational principle is a fundamental principle in physics, entailing that a physical system follows the trajectory, which minimizes its action. It is alternative to the differential equation formulation of a physical system. Applying the variational principle to the planetary interior can beautifully summarize the set of differential equations into one, which provides us some insight into the problem. From this principle, a universal mass–radius relation, an estimate of the error propagation from the equation of state to the mass–radius relation, and a form of the virial theorem applicable to planetary interiors are derived.

  20. Variational approach in transport theory

    International Nuclear Information System (INIS)

    Panta Pazos, R.; Tullio de Vilhena, M.

    2004-01-01

    In this work we present a variational approach to some methods to solve transport problems of neutral particles. We consider a convex domain X (for example the geometry of a slab, or a convex set in the plane, or a convex bounded set in the space) and we use discrete ordinates quadrature to get a system of differential equations derived from the neutron transport equation. The boundary conditions are vacuum for a subset of the boundary, and of specular reflection for the complementary subset of the boundary. Recently some different approximation methods have been presented to solve these transport problems. We introduce in this work the adjoint equations and the conjugate functions obtained by means of the variational approach. First we consider the general formulation, and then some numerical methods such as spherical harmonics and spectral collocation method. (authors)

  1. Variational approach in transport theory

    Energy Technology Data Exchange (ETDEWEB)

    Panta Pazos, R. [Nucler Engineering Department, UFRGS, Porto-Alegre (Brazil); Tullio de Vilhena, M. [Institute of Mathematics, UFRGS, Porto-Alegre (Brazil)

    2004-07-01

    In this work we present a variational approach to some methods to solve transport problems of neutral particles. We consider a convex domain X (for example the geometry of a slab, or a convex set in the plane, or a convex bounded set in the space) and we use discrete ordinates quadrature to get a system of differential equations derived from the neutron transport equation. The boundary conditions are vacuum for a subset of the boundary, and of specular reflection for the complementary subset of the boundary. Recently some different approximation methods have been presented to solve these transport problems. We introduce in this work the adjoint equations and the conjugate functions obtained by means of the variational approach. First we consider the general formulation, and then some numerical methods such as spherical harmonics and spectral collocation method. (authors)

  2. Tidal variations of earth rotation

    Science.gov (United States)

    Yoder, C. F.; Williams, J. G.; Parke, M. E.

    1981-01-01

    The periodic variations of the earths' rotation resulting from the tidal deformation of the earth by the sun and moon were rederived including terms with amplitudes of 0.002 millisec and greater. The series applies to the mantle, crust, and oceans which rotate together for characteristic tidal periods; the scaling parameter is the ratio of the fraction of the Love number producing tidal variations in the moment of inertia of the coupled mantle and oceans (k) to the dimensionless polar moment of inertia of the coupled moments (C). The lunar laser ranging data shows that k/C at monthly and fortnightly frequencies equals 0.99 + or - 0.15 and 0.99 + or - 0.20 as compared to the theoretical value of 0.94 + or - 0.04.

  3. Decadal variations in groundwater quality

    DEFF Research Database (Denmark)

    Jessen, Søren; Postma, Dieke; Thorling, Lærke

    2017-01-01

    Twenty-five years of groundwater quality monitoring in a sandy aquifer beneath agricultural fields showed large temporal and spatial variations in major ion groundwater chemistry, which were linked closely to the nitrate (NO3) content of agricultural recharge. Between 1988 and 2013, the NO3 content...... of water in the oxidized zone of the aquifer nearly halved, following implementation of action plans to reduce N leaching from agriculture. However, due to denitrification by pyrite oxidation in the aquifer, a plume of sulfate-rich water migrates through the aquifer as a legacy of the historical NO3...... loading. Agriculture thus is an important determinant of major ion groundwater chemistry. Temporal and spatial variations in the groundwater quality were simulated using a 2D reactive transport model, which combined effects of the historical NO3 leaching and denitrification, with dispersive mixing...

  4. Quantitative variation in natural populations

    International Nuclear Information System (INIS)

    Parsons, P.A.

    1975-01-01

    Quantitative variation is considered in natural populations using Drosophila as the example. A knowledge of such variation enables its rapid exploitation in directional selection experiments as shown for scutellar chaeta number. Where evidence has been obtained, genetic architectures are in qualitative agreement with Mather's concept of balance for traits under stabilizing selection. Additive genetic control is found for acute environmental stresses, but not for less acute stresses as shown by exposure to 60 Co-γ rays. D. simulans probably has a narrower ecological niche than its sibling species D. melanogaster associated with lower genetic heterogeneity. One specific environmental stress to which D. simulans is sensitive in nature is ethyl alcohol as shown by winery data. (U.S.)

  5. Bernoulli Variational Problem and Beyond

    KAUST Repository

    Lorz, Alexander

    2013-12-17

    The question of \\'cutting the tail\\' of the solution of an elliptic equation arises naturally in several contexts and leads to a singular perturbation problem under the form of a strong cut-off. We consider both the PDE with a drift and the symmetric case where a variational problem can be stated. It is known that, in both cases, the same critical scale arises for the size of the singular perturbation. More interesting is that in both cases another critical parameter (of order one) arises that decides when the limiting behaviour is non-degenerate. We study both theoretically and numerically the values of this critical parameter and, in the symmetric case, ask if the variational solution leads to the same value as for the maximal solution of the PDE. Finally we propose a weak formulation of the limiting Bernoulli problem which incorporates both Dirichlet and Neumann boundary condition. © 2013 Springer-Verlag Berlin Heidelberg.

  6. Coarse Grained Exponential Variational Autoencoders

    KAUST Repository

    Sun, Ke

    2017-02-25

    Variational autoencoders (VAE) often use Gaussian or category distribution to model the inference process. This puts a limit on variational learning because this simplified assumption does not match the true posterior distribution, which is usually much more sophisticated. To break this limitation and apply arbitrary parametric distribution during inference, this paper derives a \\\\emph{semi-continuous} latent representation, which approximates a continuous density up to a prescribed precision, and is much easier to analyze than its continuous counterpart because it is fundamentally discrete. We showcase the proposition by applying polynomial exponential family distributions as the posterior, which are universal probability density function generators. Our experimental results show consistent improvements over commonly used VAE models.

  7. On the use of antithetic variates in particle transport problems

    International Nuclear Information System (INIS)

    Milgram, M.S.

    2001-01-01

    The possible use of antithetic variates as a method of variance reduction in particle transport problems is investigated, by performing some numerical experiments. It is found that if variance reduction is not very carefully defined, it is possible, with antithetic variates, to spuriously detect reduction, or not detect true reduction. Once such subtleties are overcome, it is shown that antithetic variates can reduce variance in multidimensional integration up to a point. The phenomenon of spontaneous correlation is defined and identified as the cause of failure. The surprising result that it sometimes pays to track non-contributing particle histories is demonstrated by means of a zero variance integration analogue. The principles developed in the investigation of multi-variable integration are then employed in a simple calculation of energy deposition using the EGS4 computer code. Promising results are obtained for the total energy deposition problem, but the depth/dose problem remains unsolved. Possible means of overcoming the difficulties are suggested

  8. On Quadratic Variation of Martingales

    Indian Academy of Sciences (India)

    where D ( [ 0 , ∞ ) , R ) denotes the class of real valued r.c.l.l. functions on [ 0 , ∞ ) such that for a locally square integrable martingale ( M t ) with r.c.l.l. paths,. Ψ ( M . ( ) ) = A . ( ). gives the quadratic variation process (written usually as [ M , M ] t ) of ( M t ) . We also show that this process ( A t ) is the unique increasing ...

  9. Fractional variational principles in action

    Energy Technology Data Exchange (ETDEWEB)

    Baleanu, Dumitru [Department of Mathematics and Computer Science, Faculty of Art and Sciences, Cankaya University, 06530 Ankara (Turkey); Institute of Space Sciences, PO Box MG-23, R 76900, Magurele-Bucharest (Romania)], E-mail: dumitru@cankaya.edu.tr

    2009-10-15

    The fractional calculus has gained considerable importance in various fields of science and engineering, especially during the last few decades. An open issue in this emerging field is represented by the fractional variational principles area. Therefore, the fractional Euler-Lagrange and Hamilton equations started to be examined intensely during the last decade. In this paper, we review some new trends in this field and we discuss some of their potential applications.

  10. Variations of posterior vitreous detachment

    OpenAIRE

    Kakehashi, A.; Kado, M.; Akiba, J.; Hirokawa, H.

    1997-01-01

    AIMS—To identify variations in posterior vitreous detachment (PVD) and establish a clinical classification system for PVD.
METHODS—400 consecutive eyes were examined using biomicroscopy and vitreous photography and classified the PVD variations—complete PVD with collapse, complete PVD without collapse, partial PVD with thickened posterior vitreous cortex (TPVC), or partial PVD without TPVC.
RESULTS—In each PVD type, the most frequently seen ocular pathologies were as follows: in complete PVD ...

  11. Deep Feature Consistent Variational Autoencoder

    OpenAIRE

    Hou, Xianxu; Shen, Linlin; Sun, Ke; Qiu, Guoping

    2016-01-01

    We present a novel method for constructing Variational Autoencoder (VAE). Instead of using pixel-by-pixel loss, we enforce deep feature consistency between the input and the output of a VAE, which ensures the VAE's output to preserve the spatial correlation characteristics of the input, thus leading the output to have a more natural visual appearance and better perceptual quality. Based on recent deep learning works such as style transfer, we employ a pre-trained deep convolutional neural net...

  12. Variational integrators for reduced magnetohydrodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Kraus, Michael, E-mail: michael.kraus@ipp.mpg.de [Max-Planck-Institut für Plasmaphysik, Boltzmannstraße 2, 85748 Garching (Germany); Technische Universität München, Zentrum Mathematik, Boltzmannstraße 3, 85748 Garching (Germany); Tassi, Emanuele, E-mail: tassi@cpt.univ-mrs.fr [Aix-Marseille Université, Université de Toulon, CNRS, CPT, UMR 7332, 163 avenue de Luminy, case 907, 13288 cedex 9 Marseille (France); Grasso, Daniela, E-mail: daniela.grasso@infm.polito.it [ISC-CNR and Politecnico di Torino, Dipartimento Energia, C.so Duca degli Abruzzi 24, 10129 Torino (Italy)

    2016-09-15

    Reduced magnetohydrodynamics is a simplified set of magnetohydrodynamics equations with applications to both fusion and astrophysical plasmas, possessing a noncanonical Hamiltonian structure and consequently a number of conserved functionals. We propose a new discretisation strategy for these equations based on a discrete variational principle applied to a formal Lagrangian. The resulting integrator preserves important quantities like the total energy, magnetic helicity and cross helicity exactly (up to machine precision). As the integrator is free of numerical resistivity, spurious reconnection along current sheets is absent in the ideal case. If effects of electron inertia are added, reconnection of magnetic field lines is allowed, although the resulting model still possesses a noncanonical Hamiltonian structure. After reviewing the conservation laws of the model equations, the adopted variational principle with the related conservation laws is described both at the continuous and discrete level. We verify the favourable properties of the variational integrator in particular with respect to the preservation of the invariants of the models under consideration and compare with results from the literature and those of a pseudo-spectral code.

  13. Fast axisymmetric stability calculations using variational techniques

    International Nuclear Information System (INIS)

    Haney, S.W., Pearlstein, L.D.; Bulmer, R.H.

    1991-01-01

    A procedure for treating the axisymmetric (n = 0) stability of diverted plasmas in the presence of arbitrary, but toroidally symmetric, structures and active feedback circuits has been developed and implemented as a module in the TEQ free-boundary equilibrium code. This procedure is based on a variational solution of the ideal MHD normal mode equations. Inertia is ordered small but provides a constraint to allow the calculation of the poloidal and toroidal components of the plasma displacement. Feedback based on flux loop measurements is handled by introducing an adjoint system into the variational principle. Approximately 200 trial functions for the radial component of the plasma displacement and 200 magnetic surfaces are employed to obtain highly accurate estimates of the passive growth rate and the non-rigid eigenfunction. Nevertheless, the method is extremely fast: typically 10-20 sec of Cray 2 CPU time are required to analyze a realistic tokamak configuration. This speed, along with the direct coupling to the MHD equilibrium solver, allows interactive investigations of tokamak axisymmetric stability. Benchmarks with TSC and GATO are presented along with parameter scans for ITER and BPX. The results emphasize the importance of considering non-rigid mode effects which for ITER, yield higher nominal growth rates (non-rigid: 45 Hz, rigid: 25 Hz) and atypical internal inductance dependence (smaller l i more unstable)

  14. Spatio-temporal Variations of Abundance, Biomass, and ...

    African Journals Online (AJOL)

    The spatio-seasonal variations of Pseudodiaptomus hessei abundance, biomass and reproductive parameters were investigated in the Grand-Lahou lagoon at five stations during the dry and wet (or rainy) seasons from September 2005 to August 2006. In all sampling stations, abundance and biomass of P. hessei in the dry ...

  15. Multidimensional analysis of Drosophila wing variation in Evolution ...

    Indian Academy of Sciences (India)

    In this study, using Drosophila melanogaster isofemale lines derived from wild flies collected on both slopes of the canyon, we investigated the effect of developmental temperature upon the different components of phenotypic variation of a complex trait: the wing. Combining geometric and traditional morphometrics, we find ...

  16. Seasonal variations in aerosol optical properties over China

    Science.gov (United States)

    Yuesi Wang; Jinyuan Xin; Zhanqing Li; Shigong Wang; Pucai Wang; Wei Min Hao; Bryce L. Nordgren; Hongbin Chen; Lili Wang; Yang Sun

    2012-01-01

    Seasonal variations in background aerosol optical depth (AOD) and aerosol type are investigated over various ecosystems in China based upon three years' worth of meteorological data and data collected by the Chinese Sun Hazemeter Network. In most parts of China, AODs are at a maximum in spring or summer and at a minimum in autumn or winter. Minimum values (0.10~0....

  17. Secular variations in carbon-14 and their geophysical implications

    CSIR Research Space (South Africa)

    Vogel

    2002-03-01

    Full Text Available . The identification of the causes and magnitudes of these deviations has created a new too that is contributing to the investigation of different geophysical: phenomena. Variations in the activity of the Sun produce fluctuations of the C-14 level in the atmosphere...

  18. A Variational Approach to Perturbed Discrete Anisotropic Equations

    Directory of Open Access Journals (Sweden)

    Amjad Salari

    2016-01-01

    Full Text Available We continue the study of discrete anisotropic equations and we will provide new multiplicity results of the solutions for a discrete anisotropic equation. We investigate the existence of infinitely many solutions for a perturbed discrete anisotropic boundary value problem. The approach is based on variational methods and critical point theory.

  19. Seasonal variation of the South Indian tropical gyre

    NARCIS (Netherlands)

    Aguiar-González, B.; Ponsoni, Leandro; Ridderinkhof, H.; van Aken, H.M.; de Ruijter, W.P.M.; Maas, L.R.M.

    2016-01-01

    Based on satellite altimeter data and global atlases of temperature, salinity, wind stress and wind-driven circulation we investigate the seasonal variation of the South Indian tropical gyre and its associated open-ocean upwelling system, known as the Seychelles–Chagos Thermocline Ridge (SCTR).

  20. Seasonal variations in heavy metal concentrations in soil and some ...

    African Journals Online (AJOL)

    In this study, the seasonal variations in concentrations of the heavy metals - As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn - in soil and crops from a farm near the refuse dump site of Obafemi Awolowo University, Ile-Ife, Nigeria were investigated during the two major seasons of Nigeria. This was done to assess the pollution ...

  1. Identifying and correcting epigenetics measurements for systematic sources of variation.

    NARCIS (Netherlands)

    Perrier, Flavie; Novoloaca, Alexei; Ambatipudi, Srikant; Baglietto, Laura; Ghantous, Akram; Perduca, Vittorio; Barrdahl, Myrto; Harlid, Sophia; Ong, Ken K; Cardona, Alexia; Polidoro, Silvia; Nøst, Therese Haugdahl; Overvad, Kim; Omichessan, Hanane; Dollé, Martijn; Bamia, Christina; Huerta, José Marìa; Vineis, Paolo; Herceg, Zdenko; Romieu, Isabelle; Ferrari, Pietro

    2018-01-01

    Methylation measures quantified by microarray techniques can be affected by systematic variation due to the technical processing of samples, which may compromise the accuracy of the measurement process and contribute to bias the estimate of the association under investigation. The quantification of

  2. Applications of exterior difference systems to variations in discrete mechanics

    International Nuclear Information System (INIS)

    Xie Zheng; Li Hongbo

    2008-01-01

    In discrete mechanics, difference equations describe the fundamental physical laws and exhibit many geometric properties. Can these equations be obtained in a geometric way? Using some techniques in exterior difference systems, we investigate the discrete variational problem. As an application, we give a positive answer to the above question for the discrete Newton's, Euler-Lagrange, and Hamilton's equations

  3. Genetic variation of 12 rice cultivars grown in Brunei Darussalam ...

    African Journals Online (AJOL)

    Dell

    2015-03-25

    Mar 25, 2015 ... Quantum yield for B. berminyak were unaffected and it showed the least reduction in growth parameters studied when expose to salinity stress. From both salinity tolerance and genetic variation investigations for these 12 cultivars, it may probably be better to intercross between Arat (moderately tolerant) ...

  4. Individual variation in children's reading comprehension across digital text types

    NARCIS (Netherlands)

    Fesel, S.S.; Segers, P.C.J.; Verhoeven, L.T.W.

    2018-01-01

    The present study examined children's digital text comprehension of digital text types linear digital text vs hypertext, with or without graphical navigable overviews. We investigated to what extent individual variation in children's comprehension could be explained by lexical quality (word reading

  5. Influence of flood variation on seasonal floodplain vegetation ...

    African Journals Online (AJOL)

    This study investigated the influence of flooding variation on floodplain vegetation in the Nxaraga Lagoon seasonal floodplains by sampling community composition and soil nutrient content in 1997, when flood levels were unusually low, and again in 2010 when flood levels were unusually high. In each of the eight ...

  6. The spatial and temporal variations of nematofauna of recovering ...

    African Journals Online (AJOL)

    The spatio-temporal variations in physical sediment characteristics and nematode community assemblages were investigated and compared between a natural, a 10-year reforested, and a degraded Rhizophora mucronata mangrove ecosystem in Gazi Bay, Kenya. PCA showed a clear separation of the degraded site from ...

  7. Geotectonic variations of radon fields in Tashkent subway stations

    International Nuclear Information System (INIS)

    Yafasov, A.Ya.; Akimov, V.A.

    2001-01-01

    The anomalies of radon fields in the air of stations of Tashkent subway were investigated. These stations are located in areas with different tectonic characteristics. The influence of tectonic anomalies on formation and variations of radon fields in the environment was shown. (author)

  8. Road Traffic Accident Variations in Lagos State, Nigeria: A Synopsis ...

    African Journals Online (AJOL)

    FIRST LADY

    The major objective of this research is to examine the variation patterns of road traffic .... situation in Lagos state is bad because of the absence of effective transport ... environment as judged by the investigating officers. Also .... pattern of road traffic accident occurrence over that part of Lagos State. For ... Ph.D Thesis.

  9. Assessment of salivary flow rate: biologic variation and measure error.

    NARCIS (Netherlands)

    Jongerius, P.H.; Limbeek, J. van; Rotteveel, J.J.

    2004-01-01

    OBJECTIVE: To investigate the applicability of the swab method in the measurement of salivary flow rate in multiple-handicap drooling children. To quantify the measurement error of the procedure and the biologic variation in the population. STUDY DESIGN: Cohort study. METHODS: In a repeated

  10. Genetic variation among pelt sheep population using microsatellite ...

    African Journals Online (AJOL)

    Genetic variation in three Iranian pelt sheep breeds namely: Gray Shiraz, Zandi and Karakul were investigated using fifteen microsatellite loci. Genomic DNA was extracted from 360 blood samples by extraction kits and salting-out procedure with some modifications. The total number of alleles ranged from 6 to12 in loci.

  11. Towards Modelling Variation in Music as Foundation for Similarity

    NARCIS (Netherlands)

    Volk, A.; de Haas, W.B.; van Kranenburg, P.; Cambouropoulos, E.; Tsougras, C.; Mavromatis, P.; Pastiadis, K.

    2012-01-01

    This paper investigates the concept of variation in music from the perspective of music similarity. Music similarity is a central concept in Music Information Retrieval (MIR), however there exists no comprehensive approach to music similarity yet. As a consequence, MIR faces the challenge on how to

  12. Anatomical Variation in the Wall Thickness of Wood Fibres of ...

    African Journals Online (AJOL)

    The wall thickness of wood fibres of rubber (Hevea brasiliensis) grown and tapped for latex in south eastern Nigeria were investigated to determine anatomical variation. The rubber trees which were overmature for tapping and keeping were sampled in hierarchical order of plantations, bud classes, trees, discs, cardinal ...

  13. Variations in Wood Anatomical Characteristics of Nigerian grown ...

    African Journals Online (AJOL)

    obeche) were investigated to assess the variation pattern of fibre, vessel and ray elements. Test samples were obtained axially from butt, 10%, 30%, 50%, 70% and 90% of merchantable height (MH); and radially from inner wood, middle wood and ...

  14. Stochastic Variational Learning in Recurrent Spiking Networks

    Directory of Open Access Journals (Sweden)

    Danilo eJimenez Rezende

    2014-04-01

    Full Text Available The ability to learn and perform statistical inference with biologically plausible recurrent network of spiking neurons is an important step towards understanding perception and reasoning. Here we derive and investigate a new learning rule for recurrent spiking networks with hidden neurons, combining principles from variational learning and reinforcement learning. Our network defines a generative model over spike train histories and the derived learning rule has the form of a local Spike Timing Dependent Plasticity rule modulated by global factors (neuromodulators conveying information about ``novelty on a statistically rigorous ground.Simulations show that our model is able to learn bothstationary and non-stationary patterns of spike trains.We also propose one experiment that could potentially be performed with animals in order to test the dynamics of the predicted novelty signal.

  15. Mg II Line Variation of 32 Cygni

    Directory of Open Access Journals (Sweden)

    Young Woon Kang

    1992-12-01

    Full Text Available The Mg II lines have been extracted from the IUE archival spectra of 32 Cygni to investigate the effect of the atmospheric eclipse. The UV light curve has been reduced from the continuum flux at the center wavelength of 2807.5 Å in the IUE spectra. The equivalent width of the Mg II k absoption line has been measured for each spectra. The results of the light variation and flux tracing of the absorption line at the vicinity of the primary eclipse confirmed the atmospheric eclipse. The atmospheric effect lasted until the phase 0.06 in the absorptin line tracing, while it lasted until the phase 0.02 in the UV light curve, respectively.

  16. Stochastic variational learning in recurrent spiking networks.

    Science.gov (United States)

    Jimenez Rezende, Danilo; Gerstner, Wulfram

    2014-01-01

    The ability to learn and perform statistical inference with biologically plausible recurrent networks of spiking neurons is an important step toward understanding perception and reasoning. Here we derive and investigate a new learning rule for recurrent spiking networks with hidden neurons, combining principles from variational learning and reinforcement learning. Our network defines a generative model over spike train histories and the derived learning rule has the form of a local Spike Timing Dependent Plasticity rule modulated by global factors (neuromodulators) conveying information about "novelty" on a statistically rigorous ground. Simulations show that our model is able to learn both stationary and non-stationary patterns of spike trains. We also propose one experiment that could potentially be performed with animals in order to test the dynamics of the predicted novelty signal.

  17. Diaphasic variation and change in French pronouns

    DEFF Research Database (Denmark)

    Hansen, Anita Berit

    2013-01-01

    The French pronominal paradigm demonstrates a colloquial variation between expressing the 1st person plural as on and as nous (On est 19 dans ma classe meaning the same as Nous sommes 19 dans ma classe). This use of definite on is stigmatized by some as working class and incorrect and seen...... as a spreading feature, but seen by others as a stable stylistic ressource. The present article (inspired by Coveney 2000) investigates the speech of six young Parisians in different kinds of speech situations, in order not only to examine the possible diaphasic dimension of the on/no us alternation, but also...... to look into their other uses of on, in search of an explanation of the increasing popularity of this pronoun in French....

  18. Acquiring variation in an artificial language: Children and adults are sensitive to socially conditioned linguistic variation.

    Science.gov (United States)

    Samara, Anna; Smith, Kenny; Brown, Helen; Wonnacott, Elizabeth

    2017-05-01

    Languages exhibit sociolinguistic variation, such that adult native speakers condition the usage of linguistic variants on social context, gender, and ethnicity, among other cues. While the existence of this kind of socially conditioned variation is well-established, less is known about how it is acquired. Studies of naturalistic language use by children provide various examples where children's production of sociolinguistic variants appears to be conditioned on similar factors to adults' production, but it is difficult to determine whether this reflects knowledge of sociolinguistic conditioning or systematic differences in the input to children from different social groups. Furthermore, artificial language learning experiments have shown that children have a tendency to eliminate variation, a process which could potentially work against their acquisition of sociolinguistic variation. The current study used a semi-artificial language learning paradigm to investigate learning of the sociolinguistic cue of speaker identity in 6-year-olds and adults. Participants were trained and tested on an artificial language where nouns were obligatorily followed by one of two meaningless particles and were produced by one of two speakers (one male, one female). Particle usage was conditioned deterministically on speaker identity (Experiment 1), probabilistically (Experiment 2), or not at all (Experiment 3). Participants were given tests of production and comprehension. In Experiments 1 and 2, both children and adults successfully acquired the speaker identity cue, although the effect was stronger for adults and in Experiment 1. In addition, in all three experiments, there was evidence of regularization in participants' productions, although the type of regularization differed with age: children showed regularization by boosting the frequency of one particle at the expense of the other, while adults regularized by conditioning particle usage on lexical items. Overall, results

  19. Genetic variation in dieback resistance

    DEFF Research Database (Denmark)

    Lobo, Albin; Hansen, Jon Kehlet; McKinney, Lea Vig

    2014-01-01

    -eastern Zealand, Denmark, and confirmed the presence of substantial genetic variation in ash dieback susceptibility. The average crown damage increased in the trial from 61% in 2009 to 66% in 2012 and 72% in 2014, while the estimated heritability was 0.42 in both 2009 and 2012 but increased to 0.53 in 2014....... Genetic correlation between assessments was 0.88 between 2009 and 2012 and 0.91 between 2009 and 2014, suggesting fairly good possibilities for early selection of superior genotypes in the presence of high infection levels in the trial. The level of crown damage had strong negative effect on growth...

  20. Quadratic Variation by Markov Chains

    DEFF Research Database (Denmark)

    Hansen, Peter Reinhard; Horel, Guillaume

    We introduce a novel estimator of the quadratic variation that is based on the the- ory of Markov chains. The estimator is motivated by some general results concerning filtering contaminated semimartingales. Specifically, we show that filtering can in prin- ciple remove the effects of market...... microstructure noise in a general framework where little is assumed about the noise. For the practical implementation, we adopt the dis- crete Markov chain model that is well suited for the analysis of financial high-frequency prices. The Markov chain framework facilitates simple expressions and elegant analyti...

  1. Variational collocation on finite intervals

    International Nuclear Information System (INIS)

    Amore, Paolo; Cervantes, Mayra; Fernandez, Francisco M

    2007-01-01

    In this paper, we study a set of functions, defined on an interval of finite width, which are orthogonal and which reduce to the sinc functions when the appropriate limit is taken. We show that these functions can be used within a variational approach to obtain accurate results for a variety of problems. We have applied them to the interpolation of functions on finite domains and to the solution of the Schroedinger equation, and we have compared the performance of the present approach with others

  2. Neodymium isotopic variations in seawater

    Science.gov (United States)

    Piepgras, D. J.; Wasserburg, G. J.

    1980-01-01

    Direct measurement of the isotopic composition of Nd in the Atlantic agree with the Nd content in ferromanganese sediments and differ from the observed amounts in the Pacific samples. These data indicate the existence of distinctive differences in the isotopic composition of Nd in the waters of major oceans; the average values determined from seawater and ferromanganese sediments are considerably lower than in sources with oceanic mantle affinities showing that the REE in the oceans is dominated by continental sources. The Nd isotopic variations in seawater are applied to relate the residence time of Nd and mixing rates between the oceans.

  3. Solar cycles and climate variations

    International Nuclear Information System (INIS)

    Chistyakov, V.F.

    1990-01-01

    Climate oscillations with 100-, 200- and 300-year periods are positively correlated with solar activity oscillations: the higher is solar activity the warmer is climate. According to geological data (varved clays) it is determined, that length of cycles has decreased from 23.4 up to 11 years during latter 2.5 billion years. 12-year cycles occurred during the great glaciation periods, while 10-year cycles occurred during interglaciation periods. It is suggested, that these oscillations are related with variations of the solar activity and luminescence

  4. Variational inference & deep learning : A new synthesis

    NARCIS (Netherlands)

    Kingma, D.P.

    2017-01-01

    In this thesis, Variational Inference and Deep Learning: A New Synthesis, we propose novel solutions to the problems of variational (Bayesian) inference, generative modeling, representation learning, semi-supervised learning, and stochastic optimization.

  5. Variational inference & deep learning: A new synthesis

    OpenAIRE

    Kingma, D.P.

    2017-01-01

    In this thesis, Variational Inference and Deep Learning: A New Synthesis, we propose novel solutions to the problems of variational (Bayesian) inference, generative modeling, representation learning, semi-supervised learning, and stochastic optimization.

  6. Amazing variational approach to chemical reactions

    OpenAIRE

    Fernández, Francisco M.

    2009-01-01

    In this letter we analyse an amazing variational approach to chemical reactions. Our results clearly show that the variational expressions are unsuitable for the analysis of empirical data obtained from chemical reactions.

  7. Nonlinear variational inequalities of semilinear parabolic type

    Directory of Open Access Journals (Sweden)

    Park Jong-Yeoul

    2001-01-01

    Full Text Available The existence of solutions for the nonlinear functional differential equation governed by the variational inequality is studied. The regularity and a variation of solutions of the equation are also given.

  8. Variation along liquid isomorphs of the driving force for crystallization

    DEFF Research Database (Denmark)

    Pedersen, Ulf Rørbæk; Adrjanowicz, Karolina; Niss, Kristine

    2017-01-01

    at a reference temperature. More general analysis allows interpretation of experimental data for molecular liquids such as dimethyl phthalate and indomethacin, and suggests that the isomorph scaling exponent γ in these cases is an increasing function of density, although this cannot be seen in measurements......We investigate the variation of the driving force for crystallization of a supercooled liquid along isomorphs, curves along which structure and dynamics are invariant. The variation is weak, and can be predicted accurately for the Lennard-Jones fluid using a recently developed formalism and data...

  9. Short-time variations of the ground water level

    International Nuclear Information System (INIS)

    Nilsson, Lars Y.

    1977-09-01

    Investigations have demonstrated that the ground water level of aquifers in the Swedish bedrock shows shorttime variations without changing their water content. The ground water level is among other things affected by regular tidal movements occuring in the ''solid'' crust of the earth variations in the atmospheric pressure strong earthquakes occuring in different parts of the world These effects proves that the system of fissures in the bedrock are not stable and that the ground water flow is influenced by both water- and airfilled fissures

  10. Geographic variation in speed of seed germination in central Oregon ponderosa pine (Pinus ponderosa Dougl. ex Laws.).

    Science.gov (United States)

    John C. Weber; Frank C. Sorensen

    1992-01-01

    Variation in speed of seed germination was investigated among ponderosa pine trees representing 225 locations in central Oregon. Results suggested that at least some of the geographic variation is related to the severity of summer drought. In general, germination speed was greater in locations with shod, drought-limited growing seasons. Levels of geographic variation...

  11. Homogenization of variational inequalities for obstacle problems

    International Nuclear Information System (INIS)

    Sandrakov, G V

    2005-01-01

    Results on the convergence of solutions of variational inequalities for obstacle problems are proved. The variational inequalities are defined by a non-linear monotone operator of the second order with periodic rapidly oscillating coefficients and a sequence of functions characterizing the obstacles. Two-scale and macroscale (homogenized) limiting variational inequalities are obtained. Derivation methods for such inequalities are presented. Connections between the limiting variational inequalities and two-scale and macroscale minimization problems are established in the case of potential operators.

  12. Importance of Local Structural Variations on Recrystallization

    DEFF Research Database (Denmark)

    Juul Jensen, Dorte; Lin, Fengxiang; Zhang, Yubin

    2013-01-01

    Effects of local variations in the deformation microstructure on subsequent recrystallization are discussed and illustrated by three examples. The three examples consider local variations on different length scales and are: 1. Effects of local variations in the deformation microstructure on the f...

  13. Thermochemical investigation of lithium-vanadium bronzes

    International Nuclear Information System (INIS)

    Filippova, S.E.; Kesler, Ya.A.; Tret'yakov, Yu.D.; Gordeev, I.V.

    1979-01-01

    A thermochemical investigation was carried out of lithium-vanadium bronzes. The enthalpies of solution and the standard enthalpies of formation of the bronzes β-Lisub(x)Vsub(2)Osub(5) were determined. Investigated was the dependence of the enthalpy of mixing bronzes on the composition; a linear character of the dependence evidences of negligibly small, as compared to the experimental error, energy variations of the matrix V 2 O 5 on introduction of lithium. The variation was calculated of the partial molar enthalpy of lithium in the formation of β-Lisub(x)Vsub(2)Osub(5)

  14. Geographic variation in lumbar diskectomy: a protocol for evaluation.

    Science.gov (United States)

    Barron, M; Kazandjian, V A

    1992-03-01

    In 1989 the Maryland Hospital Association (MHA) began developing a protocol related to lumbar diskectomy, a procedure with widely reported geographic variation in its use. The MHA's Laminectomy Advisory Committee drafted three criteria for performance of lumbar diskectomy and also developed a data-collection instrument with which the eight hospitals participating in a pilot study could abstract the necessary data from medical records. Both individual hospital and aggregate results showed wide variation in compliance with the criteria. These findings suggest research and development activities such as refinement of the data-collection instrument, use of the protocol for bench-marking, further investigation of clinical and other determinants of rate variation, and study of the effect of new diagnostic technology on utilization rates for this procedure.

  15. Geographic Variations in the EPR Spectrum of Tooth Enamel

    International Nuclear Information System (INIS)

    Romanyukha, A.A.; Hayes, R.B.; Haskell, E.H.; Kenner, G.H.

    1999-01-01

    The presence of stable radiation-induced radicals in the mineral component of tooth enamel allows use of this material as a biological dosemeter. Estimation of the dose absorbed in tooth enamel can be done by EPR. Generally, for the purpose of dose reconstruction, the EPR spectrum of tooth enamel is interpreted in terms of two main components. The first is a broad background signal often called the native signal centered at a g value of 2.0045. The origin of this signal is not precisely known. The second main component in the tooth enamel spectrum is purely radiation induced and can be used for retrospective dosimetry. Internal structure of the native signal and variations of its amplitude and linewidth were investigated for the samples prepared from modern teeth obtained from different geographic locations (USA and Russia). Possible reasons for the variations observed are discussed as are the potential effects of the variations on the reliability of dose estimation. (author)

  16. Molecular Darwinism: the contingency of spontaneous genetic variation.

    Science.gov (United States)

    Arber, Werner

    2011-01-01

    The availability of spontaneously occurring genetic variants is an important driving force of biological evolution. Largely thanks to experimental investigations by microbial geneticists, we know today that several different molecular mechanisms contribute to the overall genetic variations. These mechanisms can be assigned to three natural strategies to generate genetic variants: 1) local sequence changes, 2) intragenomic reshuffling of DNA segments, and 3) acquisition of a segment of foreign DNA. In these processes, specific gene products are involved in cooperation with different nongenetic elements. Some genetic variations occur fully at random along the DNA filaments, others rather with a statistical reproducibility, although at many possible sites. We have to be aware that evolution in natural ecosystems is of higher complexity than under most laboratory conditions, not at least in view of symbiotic associations and the occurrence of horizontal gene transfer. The encountered contingency of genetic variation can possibly best ensure a long-term persistence of life under steadily changing living conditions.

  17. Optimally stopped variational quantum algorithms

    Science.gov (United States)

    Vinci, Walter; Shabani, Alireza

    2018-04-01

    Quantum processors promise a paradigm shift in high-performance computing which needs to be assessed by accurate benchmarking measures. In this article, we introduce a benchmark for the variational quantum algorithm (VQA), recently proposed as a heuristic algorithm for small-scale quantum processors. In VQA, a classical optimization algorithm guides the processor's quantum dynamics to yield the best solution for a given problem. A complete assessment of the scalability and competitiveness of VQA should take into account both the quality and the time of dynamics optimization. The method of optimal stopping, employed here, provides such an assessment by explicitly including time as a cost factor. Here, we showcase this measure for benchmarking VQA as a solver for some quadratic unconstrained binary optimization. Moreover, we show that a better choice for the cost function of the classical routine can significantly improve the performance of the VQA algorithm and even improve its scaling properties.

  18. Variational identities and Hamiltonian structures

    International Nuclear Information System (INIS)

    Ma Wenxiu

    2010-01-01

    This report is concerned with Hamiltonian structures of classical and super soliton hierarchies. In the classical case, basic tools are variational identities associated with continuous and discrete matrix spectral problems, targeted to soliton equations derived from zero curvature equations over general Lie algebras, both semisimple and non-semisimple. In the super case, a supertrace identity is presented for constructing Hamiltonian structures of super soliton equations associated with Lie superalgebras. We illustrate the general theories by the KdV hierarchy, the Volterra lattice hierarchy, the super AKNS hierarchy, and two hierarchies of dark KdV equations and dark Volterra lattices. The resulting Hamiltonian structures show the commutativity of each hierarchy discussed and thus the existence of infinitely many commuting symmetries and conservation laws.

  19. Circadian Variation Of Stroke Onset

    Directory of Open Access Journals (Sweden)

    Kamath vasantha

    2003-01-01

    Full Text Available Diurnal variations in various physiological and biochemical functions and certain pathological events like myocardial infarction and stroke have been documented. We studied prospectively one hundred and seven patients of acute onset stroke confirmed by computed tomography for the exact time of onset, risk factors and type of stroke. Patients who were unclear of time of onset and with a diagnosis of cerebral venous thrombosis or sub-arachnoid hemorrhage were excluded. Infarction was detected in 71 patients and hemorrhage in 33 patients. Men out numbered women (1:6:1. Hypertension was more frequent in hemorrhage in the morning time (5 AM-12 noon and more infarction between 12-6 pm. However there was no relation between the time of onset of stroke and various risk-factors of stroke.

  20. Generalized Multiparameters Fractional Variational Calculus

    Directory of Open Access Journals (Sweden)

    Om Prakash Agrawal

    2012-01-01

    Full Text Available This paper builds upon our recent paper on generalized fractional variational calculus (FVC. Here, we briefly review some of the fractional derivatives (FDs that we considered in the past to develop FVC. We first introduce new one parameter generalized fractional derivatives (GFDs which depend on two functions, and show that many of the one-parameter FDs considered in the past are special cases of the proposed GFDs. We develop several parts of FVC in terms of one parameter GFDs. We point out how many other parts could be developed using the properties of the one-parameter GFDs. Subsequently, we introduce two new two- and three-parameter GFDs. We introduce some of their properties, and discuss how they can be used to develop FVC. In addition, we indicate how these formulations could be used in various fields, and how the generalizations presented here can be further extended.

  1. Variation of the latissimus dorsi

    Directory of Open Access Journals (Sweden)

    Ishani P Shah

    2014-01-01

    Full Text Available A typical muscle variation of latissimus dorsi - the axillary arch is represented by the muscular or fibromuscular slip detached from the anteroinferior border of the musculus latissimus dorsi passing over the axilla under the axillary fascia crossing the medial side of the brachial plexus to continue as a septum intermusculare mediale brachii distally to the medial epicondyle of humerus. The full extent of the muscle is rarely present. Slips of muscle extend from the latissimus dorsi at the inferior angle of scapula to insert into pectoralis major (Langer, coracobrachilis, biceps or coracoid process forming what is described as a common variant - the muscular axillary arch. We report three cases of variants of latissimus dorsi, one of which has not been reported in the literature before.

  2. Variational transition-state theory

    International Nuclear Information System (INIS)

    Truhlar, D.G.; Garrett, B.C.

    1980-01-01

    A general introduction to and some results from studies of a procedure called variational transition-state theory are presented. A fundamental assumption of this theory is that the net rate of forward reaction at equilibrium equals the equilibrium flux in the product direction through the transition state where the transition state is a surface in phase space dividing reactants from products. Classical generalized-transition-state-theory calculations for nine collinear systems are compared to classical trajectory calculations. This new technique should provide useful insight into the successes and failures of the conventional theory and useful quantitative estimates of possible errors on the predictions of conventional transition-state theory. This should also contribute to a more accurate theory now available for the practical calculations of chemical reaction rates and thermochemical and structural interpretations of rate processes

  3. Variational methods for field theories

    Energy Technology Data Exchange (ETDEWEB)

    Ben-Menahem, S.

    1986-09-01

    Four field theory models are studied: Periodic Quantum Electrodynamics (PQED) in (2 + 1) dimensions, free scalar field theory in (1 + 1) dimensions, the Quantum XY model in (1 + 1) dimensions, and the (1 + 1) dimensional Ising model in a transverse magnetic field. The last three parts deal exclusively with variational methods; the PQED part involves mainly the path-integral approach. The PQED calculation results in a better understanding of the connection between electric confinement through monopole screening, and confinement through tunneling between degenerate vacua. This includes a better quantitative agreement for the string tensions in the two approaches. Free field theory is used as a laboratory for a new variational blocking-truncation approximation, in which the high-frequency modes in a block are truncated to wave functions that depend on the slower background modes (Boron-Oppenheimer approximation). This ''adiabatic truncation'' method gives very accurate results for ground-state energy density and correlation functions. Various adiabatic schemes, with one variable kept per site and then two variables per site, are used. For the XY model, several trial wave functions for the ground state are explored, with an emphasis on the periodic Gaussian. A connection is established with the vortex Coulomb gas of the Euclidean path integral approach. The approximations used are taken from the realms of statistical mechanics (mean field approximation, transfer-matrix methods) and of quantum mechanics (iterative blocking schemes). In developing blocking schemes based on continuous variables, problems due to the periodicity of the model were solved. Our results exhibit an order-disorder phase transition. The transfer-matrix method is used to find a good (non-blocking) trial ground state for the Ising model in a transverse magnetic field in (1 + 1) dimensions.

  4. MDCT evaluation of sternal variations: Pictorial essay

    International Nuclear Information System (INIS)

    Duraikannu, Chary; Noronha, Olma V; Sundarrajan, Pushparajan

    2016-01-01

    Sternal variations and anomalies have been identified in the past during autopsy or cadaveric studies. Recently, an increasing number of minor sternal variations have been reported with the advent of multidetector computed tomography (CT). Although there are many sternal variations that occur with varying appearance and prevalence, most of them are not recognized or are underreported during routine imaging of thorax. Identification of sternal variations is important to differentiate from pathological conditions and to prevent fatal complications prior to sternal interventions like marrow aspiration or acupuncture. This article aims to describe the minor and asymptomatic sternal variations by multidetector CT and their clinical significance

  5. The Body as a Substrate of Differentiation. Shifting the Focus from Race Science to Life Scientists' Research on Human Variation

    OpenAIRE

    Lipphardt, Veronika

    2017-01-01

    Abstract This article suggests to focus on the history of human variation instead of focussing on the history of race science. It views the latter as a subset of the former, hence views race science as embedded into the larger field of life scientists' investigations into human variation. This paper explores why human variation is such an attractive and productive object particularly for the life sciences. It proposes that knowledge about human variation is incomplete in a promising way, and ...

  6. Accommodating variation: dialects, idiolects, and speech processing.

    Science.gov (United States)

    Kraljic, Tanya; Brennan, Susan E; Samuel, Arthur G

    2008-04-01

    Listeners are faced with enormous variation in pronunciation, yet they rarely have difficulty understanding speech. Although much research has been devoted to figuring out how listeners deal with variability, virtually none (outside of sociolinguistics) has focused on the source of the variation itself. The current experiments explore whether different kinds of variation lead to different cognitive and behavioral adjustments. Specifically, we compare adjustments to the same acoustic consequence when it is due to context-independent variation (resulting from articulatory properties unique to a speaker) versus context-conditioned variation (resulting from common articulatory properties of speakers who share a dialect). The contrasting results for these two cases show that the source of a particular acoustic-phonetic variation affects how that variation is handled by the perceptual system. We also show that changes in perceptual representations do not necessarily lead to changes in production.

  7. Matter tensor from the Hilbert variational principle

    International Nuclear Information System (INIS)

    Pandres, D. Jr.

    1976-01-01

    We consider the Hilbert variational principle which is conventionally used to derive Einstein's equations for the source-free gravitational field. We show that at least one version of the equivalence principle suggests an alternative way of performing the variation, resulting in a different set of Einstein equations with sources automatically present. This illustrates a technique which may be applied to any theory that is derived from a variational principle and that admits a gauge group. The essential point is that, if one first imposes a gauge condition and then performs the variation, one obtains field equations with source terms which do not appear if one first performs the variation and then imposes the gauge condition. A second illustration is provided by the variational principle conventionally used to derive Maxwell's equations for the source-free electromagnetic field. If one first imposes the Lorentz gauge condition and then performs the variation, one obtains Maxwell's equations with sources present

  8. Unexpectedly high genetic variation in large unisexual clumps of the subdioecious plant Honckenya peploides

    DEFF Research Database (Denmark)

    Sánchez-Vilas, Julia; Philipp, Marianne; Retuerto, Rubén

    2010-01-01

    Honckenya peploides is a subdioecious dune plant that reproduces both sexually and by clonal growth. In northwest Spain this species was found to exhibit an extreme spatial segregation of the sexes, and our objective was to investigate genetic variation in unisexual clumps. Genetic variation was ...

  9. Developmental stage of strongyle eggs affects the outcome variations of real-time PCR analysis

    DEFF Research Database (Denmark)

    Andersen, Ulla Vestergaard; Haakansson, I. T.; Roust, Tina

    2013-01-01

    extent developmental stages can affect the variation of diagnostic test results. This study investigated the influence of developmental stages of strongyle eggs on the variation real-time polymerase chain reaction (PCR) results. Mixed species strongyle eggs were obtained from the faeces of a naturally...

  10. Spatial and seasonal variations of the contamination within water body of the Grand Canal, China

    NARCIS (Netherlands)

    Wang, X.L.; Han, Jingyi; Xu, L.G.; Zhang, Q.

    2010-01-01

    To delineate the character of contaminations in the Grand Canal, China, a three-year study (2004-2006) was conducted to investigate variations the water quality in the canal. Results showed that the variation of water quality within the Grand Canal was of there is remarkable spatial and seasonal

  11. Parents or predators: Examining intraseasonal variation in nest survival for migratory passerine

    Science.gov (United States)

    Robin Hirsch-Jacobson; W. Andrew Cox; Emily E. Tewes; Frank R., III Thompson; John. Faaborg

    2012-01-01

    For birds, risk of nest predation can vary within a breeding season, but few data exist that explain why such variation occurs. We investigated intraseasonal variation of nest survival of the Acadian Flycatcher (Empidonax virescens) in Midwestern forests and tested whether four of the adults' reproductive strategies (clutch size, nest...

  12. The Effect of Intertalker Variations on Acoustic-Perceptual Mapping in Cantonese and Mandarin Tone Systems

    Science.gov (United States)

    Peng, Gang; Zhang, Caicai; Zheng, Hong-Ying; Minett, James W.; Wang, William S.-Y.

    2012-01-01

    Purpose: This study investigates the impact of intertalker variations on the process of mapping acoustic variations on tone categories in two different tone languages. Method: Pitch stimuli manipulated from four voice ranges were presented in isolation through a blocked-talker design. Listeners were instructed to identify the stimuli that they…

  13. Radial variation in fiber length of some lesser used wood species in ...

    African Journals Online (AJOL)

    Variations in fibre length of ten lesser used wood species were investigated. The mean fibre length varied from 1.07mm in Lannea acida to 2.41mm in Sterculia setigera. Four patterns of within tree radial variations in fibre length were observed in the studied species. In pattern one, fibre length increased from the pith to the ...

  14. Structural genomic variation in ischemic stroke

    Science.gov (United States)

    Matarin, Mar; Simon-Sanchez, Javier; Fung, Hon-Chung; Scholz, Sonja; Gibbs, J. Raphael; Hernandez, Dena G.; Crews, Cynthia; Britton, Angela; Wavrant De Vrieze, Fabienne; Brott, Thomas G.; Brown, Robert D.; Worrall, Bradford B.; Silliman, Scott; Case, L. Douglas; Hardy, John A.; Rich, Stephen S.; Meschia, James F.; Singleton, Andrew B.

    2008-01-01

    Technological advances in molecular genetics allow rapid and sensitive identification of genomic copy number variants (CNVs). This, in turn, has sparked interest in the function such variation may play in disease. While a role for copy number mutations as a cause of Mendelian disorders is well established, it is unclear whether CNVs may affect risk for common complex disorders. We sought to investigate whether CNVs may modulate risk for ischemic stroke (IS) and to provide a catalog of CNVs in patients with this disorder by analyzing copy number metrics produced as a part of our previous genome-wide single-nucleotide polymorphism (SNP)-based association study of ischemic stroke in a North American white population. We examined CNVs in 263 patients with ischemic stroke (IS). Each identified CNV was compared with changes identified in 275 neurologically normal controls. Our analysis identified 247 CNVs, corresponding to 187 insertions (76%; 135 heterozygous; 25 homozygous duplications or triplications; 2 heterosomic) and 60 deletions (24%; 40 heterozygous deletions;3 homozygous deletions; 14 heterosomic deletions). Most alterations (81%) were the same as, or overlapped with, previously reported CNVs. We report here the first genome-wide analysis of CNVs in IS patients. In summary, our study did not detect any common genomic structural variation unequivocally linked to IS, although we cannot exclude that smaller CNVs or CNVs in genomic regions poorly covered by this methodology may confer risk for IS. The application of genome-wide SNP arrays now facilitates the evaluation of structural changes through the entire genome as part of a genome-wide genetic association study. PMID:18288507

  15. Anatomical variation of human thoracic rib in dry bone.

    Directory of Open Access Journals (Sweden)

    Dr. Nalini Konkani

    2017-12-01

    Full Text Available Introduction: The Ribs are essential structure of osseous thorax and provide information that aids in the interpretation of radiologic images. The purpose of this study to investigate variations in thoracic rib and its morphological & clinical importance. So, In present study attempted to find out additional intercostal spaces due to bifurcation of ribs, less intercostal space due to fusion of ribs, variation of the normal ribs like, gap in the rib, fusion of one rib to another at a shaft of rib. Congenital abnormalities of the ribs are usually asymptomatic, often discovered incidentally on chest X-ray. Effects of this neuroskeletal anomaly can include respiratory difficulties and neurological limitations.Material & Method: The study was carried out in Bone Store of Department of Anatomy, B. J. Medical College, Ahmedabad, Gujarat. Study was carried out on 500 human dried ribs. And the variations in the ribs are studied. We got variation in the human ribs and studied. Result : Variations were seen like out of 500 ribs, Bifid rib having two ends 9(1.8%, rib having bifid space 2(0.4%, fusion rib at the level of shaft 1(0.2%, fusion of first rib and second rib 1(0.2%,first rib having two ends 1(0.2%. Conclusion: Bifid rib is an anatomical variant where the sternal end of the rib is cleaved into two. So we can rule out mesodermal abnormalities, parenchymal lung disease, chest wall tumor or costal fracture.

  16. Variations in the origin of inferior phrenic arteries and their relationship to celiac axis variations on CT angiography

    Energy Technology Data Exchange (ETDEWEB)

    Aslaner, Ramazan; Pekcevik, Yeliz; Sahin, Hilal [Dept. of Radiology, Tepecik Training and Research Hospital, Izmir (Turkmenistan); Toka, Onur [Dept. of Statistics, Hacettepe University, Ankara (Turkmenistan)

    2017-04-15

    Knowing the origin of the inferior phrenic artery (IPA) is important prior to surgical interventions and interventional radiological procedures related to IPA. We aimed to identify variations in the origin of IPA and to investigate the relationship between the origin of IPA and celiac axis variations using computed tomography angiography (CTA). The CTA images of 1000 patients (737 male and 263 female, the mean age 60, range 18–94 years) were reviewed in an analysis of IPA and celiac axis variations. The origin of IPA was divided into two groups, those originating as a common trunk and those originating independently without a truncus. The relationship between the origin of IPA and celiac axis variation was analyzed using Pearson's chi-square test. Both IPAs originated from a common trunk in 295 (29.5%) patients. From which the majority of the common trunk originated from the aorta. Contrastingly, the inferior phrenic arteries originated from different origins in 705 (70.5%) patients. The majority of the right inferior phrenic artery (RIPA) and the left inferior phrenic artery (LIPA) originated independently from the celiac axis. Variation in the celiac axis were detected in 110 (11%) patients. The origin of IPA was found to be significantly different in the presence of celiac axis variation. The majority of IPA originated from the aorta in patients with a common IPA trunk, while the majority of RIPA and LIPA originating from the celiac axis in patients without a common IPA trunk. Thus, the origin of IPA may widely differ in the presence of celiac axis variation.

  17. Variations in the origin of inferior phrenic arteries and their relationship to celiac axis variations on CT angiography

    International Nuclear Information System (INIS)

    Aslaner, Ramazan; Pekcevik, Yeliz; Sahin, Hilal; Toka, Onur

    2017-01-01

    Knowing the origin of the inferior phrenic artery (IPA) is important prior to surgical interventions and interventional radiological procedures related to IPA. We aimed to identify variations in the origin of IPA and to investigate the relationship between the origin of IPA and celiac axis variations using computed tomography angiography (CTA). The CTA images of 1000 patients (737 male and 263 female, the mean age 60, range 18–94 years) were reviewed in an analysis of IPA and celiac axis variations. The origin of IPA was divided into two groups, those originating as a common trunk and those originating independently without a truncus. The relationship between the origin of IPA and celiac axis variation was analyzed using Pearson's chi-square test. Both IPAs originated from a common trunk in 295 (29.5%) patients. From which the majority of the common trunk originated from the aorta. Contrastingly, the inferior phrenic arteries originated from different origins in 705 (70.5%) patients. The majority of the right inferior phrenic artery (RIPA) and the left inferior phrenic artery (LIPA) originated independently from the celiac axis. Variation in the celiac axis were detected in 110 (11%) patients. The origin of IPA was found to be significantly different in the presence of celiac axis variation. The majority of IPA originated from the aorta in patients with a common IPA trunk, while the majority of RIPA and LIPA originating from the celiac axis in patients without a common IPA trunk. Thus, the origin of IPA may widely differ in the presence of celiac axis variation

  18. Variations in the Origin of Inferior Phrenic Arteries and Their Relationship to Celiac Axis Variations on CT Angiography.

    Science.gov (United States)

    Aslaner, Ramazan; Pekcevik, Yeliz; Sahin, Hilal; Toka, Onur

    2017-01-01

    Knowing the origin of the inferior phrenic artery (IPA) is important prior to surgical interventions and interventional radiological procedures related to IPA. We aimed to identify variations in the origin of IPA and to investigate the relationship between the origin of IPA and celiac axis variations using computed tomography angiography (CTA). The CTA images of 1000 patients (737 male and 263 female, the mean age 60, range 18-94 years) were reviewed in an analysis of IPA and celiac axis variations. The origin of IPA was divided into two groups, those originating as a common trunk and those originating independently without a truncus. The relationship between the origin of IPA and celiac axis variation was analyzed using Pearson's chi-square test. Both IPAs originated from a common trunk in 295 (29.5%) patients. From which the majority of the common trunk originated from the aorta. Contrastingly, the inferior phrenic arteries originated from different origins in 705 (70.5%) patients. The majority of the right inferior phrenic artery (RIPA) and the left inferior phrenic artery (LIPA) originated independently from the celiac axis. Variation in the celiac axis were detected in 110 (11%) patients. The origin of IPA was found to be significantly different in the presence of celiac axis variation. The majority of IPA originated from the aorta in patients with a common IPA trunk, while the majority of RIPA and LIPA originating from the celiac axis in patients without a common IPA trunk. Thus, the origin of IPA may widely differ in the presence of celiac axis variation.

  19. [Correlation of intraocular pressure variation after visual field examination with 24-hour intraocular pressure variations in primary open-angle glaucoma].

    Science.gov (United States)

    Noro, Takahiko; Nakamoto, Kenji; Sato, Makoto; Yasuda, Noriko; Ito, Yoshinori; Ogawa, Shumpei; Nakano, Tadashi; Tsuneoka, Hiroshi

    2014-10-01

    We retrospectively examined intraocular pressure variations after visual field examination in primary open angle glaucoma (POAG), together with its influencing factors and its association with 24-hour intraocular pressure variations. Subjects were 94 eyes (52 POAG patients) subjected to measurements of 24-hour intraocular pressure and of changes in intraocular pressure after visual field examination using a Humphrey Visual Field Analyzer. Subjects were classified into three groups according to the magnitude of variation (large, intermediate and small), and 24-hour intraocular pressure variations were compared among the three groups. Factors influencing intraocular pressure variations after visual field examination and those associated with the large variation group were investigated. Average intraocular pressure variation after visual field examination was -0.28 ± 1.90 (range - 6.0(-) + 5.0) mmHg. No significant influencing factors were identified. The intraocular pressure at 3 a.m. was significantly higher in the large variation group than other two groups (p field examination. Increases in intraocular pressure during the night might be associated with large intraocular pressure variations after visual field examination.

  20. Variations in the small-scale galactic magnetic field and short time-scale intensity variations of extragalactic radio sources

    International Nuclear Information System (INIS)

    Simonetti, J.H.

    1985-01-01

    Structure functions of the Faraday rotation measures (RMs) of extragalactic radio sources are used to investigate variations in the interstellar magnetic field on length scales of approx.0.01 to 100 pc. Model structure functions derived assuming a power-law power spectrum of irregularities in n/sub e/B, are compared with those observed. The results indicate an outer angular scale for RM variations of approximately less than or equal to 5 0 and evidence for RM variations on scales as small as 1'. Differences in the variance of n/sub e/B fluctuations for various lines of sight through the Galaxy are found. Comparison of pulsar scintillations in right- and left-circular polarizations yield an upper limit to the variations in n/sub e/ on a length scale of approx.10 11 cm. RMs were determined through high-velocity molecular flows in galactic star-formation regions, with the goal of constraining magnetic fields in and near the flows. RMs of 7 extragalactic sources with a approx.20 arcmin wide area seen through Cep A, fall in two groups separated by approx.150 rad m -2 - large given our knowledge of RM variations on small angular scales and possibly a result of the anisotropy of the high-velocity material

  1. Genetic variation in resistance to ionizing radiation

    International Nuclear Information System (INIS)

    Ayala, F.J.

    1991-01-01

    We proposed an investigation of genetically-determined individual differences in sensitivity to ionizing radiation. The model organism is Drosophila melanogaster. The gene coding for Cu,Zn superoxide dismutase (SOD) is the target locus, but the effects of variation in other components of the genome that modulate SOD levels are also taken into account. SOD scavenges oxygen radicals generated during exposure to ionizing radiation. It has been shown to protect against ionizing radiation damage to DNA, viruses, bacteria, mammalian cells, whole mice, and Drosophila. Two alleles, S and F, are commonly found in natural populations of D. melanogaster; in addition we have isolated from a natural population ''null'' (CA1) mutant that yields only 3.5% of normal SOD activity. The S, F, and CA1 alleles provide an ideal model system to investigate SOD-dependent radioresistance, because each allele yields different levels of SOD, so that S > F >> CA1. The roles of SOD level in radioresistance are being investigated in a series of experiments that measure the somatic and germ-line effects of increasing doses of ionizing radiation. In addition, we have pursued an unexpected genetic event-namely the nearly simultaneous transformation of several lines homozygous for the SOD ''null'' allele into predominately S lines. Using specifically designed probes and DNA amplification by means of the Tag polymerase chain reaction (PCR) we have shown that (1) the null allele was still present in the transformed lines, but was being gradually replaced by the S allele as a consequence of natural selection; and (2) that the transformation was due to the spontaneous deletion of a 0.68 Kb truncated P-element, the insertion of which is characteristic of the CA1 null allele

  2. Variations of microstructure and properties of 690 MPa grade low carbon bainitic steel after tempering

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Rui [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan Shandong 250061 (China); School of Materials Science and Engineering, Shandong University, Jinan Shandong 250061 (China); Li, Shengli, E-mail: lishengli@sdu.edu.cn [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan Shandong 250061 (China); School of Materials Science and Engineering, Shandong University, Jinan Shandong 250061 (China); Li, Zhenshun; Tian, Lei [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan Shandong 250061 (China); School of Materials Science and Engineering, Shandong University, Jinan Shandong 250061 (China)

    2012-12-15

    The variations of microstructure, mechanical properties and electrical resistivity of 690 MPa grade low carbon bainitic steel tempered at different temperatures were investigated with Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and double-arm Bridge. The results show that the appearance of granular bainite, decomposition of retained austenite, variations of dislocation density and solid solution of microalloying elements are the main reasons for variations of mechanical properties and electrical resistivity. Electrical resistivity reflects the solution content of microalloying elements and variations of dislocation density, which can be used as a fast and effective way to analyze the microstructure of materials.

  3. State Variation in Medical Imaging: Despite Great Variation, the Medicare Spending Decline Continues.

    Science.gov (United States)

    Rosenkrantz, Andrew B; Hughes, Danny R; Duszak, Richard

    2015-10-01

    The purpose of this study was to assess state-level trends in per beneficiary Medicare spending on medical imaging. Medicare part B 5% research identifiable files from 2004 through 2012 were used to compute national and state-by-state annual average per beneficiary spending on imaging. State-to-state geographic variation and temporal trends were analyzed. National average per beneficiary Medicare part B spending on imaging increased 7.8% annually between 2004 ($350.54) and its peak in 2006 ($405.41) then decreased 4.4% annually between 2006 and 2012 ($298.63). In 2012, annual per beneficiary spending was highest in Florida ($367.25) and New York ($355.67) and lowest in Ohio ($67.08) and Vermont ($72.78). Maximum state-to-state geographic variation increased over time, with the ratio of highest-spending state to lowest-spending state increasing from 4.0 in 2004 to 5.5 in 2012. Spending in nearly all states decreased since peaks in 2005 (six states) or 2006 (43 states). The average annual decrease among states was 5.1% ± 1.8% (range, 1.2-12.2%) The largest decrease was in Ohio. In only two states did per beneficiary spending increase (Maryland, 12.5% average annual increase since 2005; Oregon, 4.8% average annual increase since 2008). Medicare part B average per beneficiary spending on medical imaging declined in nearly every state since 2005 and 2006 peaks, abruptly reversing previously reported trends. Spending continued to increase, however, in Maryland and Oregon. Identification of state-level variation may facilitate future investigation of the potential effect of specific and regional changes in spending on patient access and outcomes.

  4. PLURILINGUAL COMPETENCE, STYLES AND VARIATION

    Directory of Open Access Journals (Sweden)

    Jyrki Kalliokoski

    2011-01-01

    Full Text Available The paper explores plurilingual competence in respect to language proficiency, language education and pluri- and multilingualism. The notion of communicative competence was introduced by Hymes (1972 as a reaction to chomskyan view of language as an autonomous system. Hymes’ notion of communicative competence originally included plurilingualism. The concept of communicative competence was quickly adopted to applied linguistics but the idea of a linguistic repertoire consisting of the competencies of linguistic varieties was not imported to SLA or language testing. The Hymesian perspective to plurilingualism as an essential dimension of communicative competence was revived in the Common European Framework (CEFR. However,the practice of applying the CEFR has mostly neglected the dimension on plurilingualism and plurilingual competence. The focus in the use of the CEFR has been on the different areas of language skills within one single language at a time, while the application of plurilingual practices has gained very little attention. The Hymesian notion of communicative competence has lived on in the sociolinguistic research tradition, especially within interactional sociolinguistics. The present paper relates the notion of plurilingual competence to its hymesian origin, to recent trends in plurilingual and pluricultural education, and to the sociolinguistic study of style and linguistic variation in multilingual communities. The article uses Finnish L2 data to show how plurilingual competence is used as an interactional resource.From the perspective of language learning, plurilingual competence enables speakers with different linguistic backgrounds to use their shared linguistic repertoire in order to ensure smooth interaction and achieve mutual understanding.

  5. Isotopic variations in primitive meteorites

    International Nuclear Information System (INIS)

    Clayton, R.N.; Chicago Univ., IL; Chicago Univ., IL

    1981-01-01

    The presence of large internal 16 O variability in ordinary chondrites greatly extends the range of meteorite types in which this phenomenon has been observed. These results may lead to identification of major gas and dust reservoirs in the cloud from which the Solar System formed. The demonstration that live 107 Pd was present in the differentiated parent bodies of some iron meteorites supports the million year time scale between a major nucleosynthetic event and Solar System formation, as implied by the presence of live 26 Al in carbonaceous chondrites. However, the variability of radiogenic 26 Mg abundances in these meteorites makes it clear that the data cannot be interpreted simply in terms of time variations. Models of nucleosynthesis for elements from calcium to the iron peak should be aided by the new observations of abundances of titanium isotopes. Progress has been made in establishing the carrier phases of isotopically anomalous xenon and krypton. The apparent location of anomalous xenon and 14 N-rich nitrogen in identical carriers supports the notion that nucleosynthetic anomalies in nitrogen are also present in Allende. (author)

  6. Variation of respiratory syncytial virus and the relation with meteorological factors in different winter seasons.

    NARCIS (Netherlands)

    Meerhoff, T.J.; Paget, W.J.; Kimpen, J.L.; Schellevis, F.

    2009-01-01

    Background: Respiratory syncytial virus (RSV) is the most important viral agent causing severe respiratory disease in infants and children. In temperate climates, RSV activity typically peaks during winter. We have described the seasonal variation in RSV activity and investigated which

  7. Seasonal variations in the fouling diatom community structure from a monsoon influenced tropical estuary

    Digital Repository Service at National Institute of Oceanography (India)

    Mitbavkar, S.; Anil, A.C.

    Seasonal variations in the fouling diatom community from a monsoon influenced tropical estuary were investigated. The community composition did not differ significantly between stainless steel and polystyrene substrata due to dominance by Navicula...

  8. Host genome variations and risk of infections during induction treatment for childhood acute lymphoblastic leukaemia

    DEFF Research Database (Denmark)

    Lund, Bendik; Wesolowska-Andersen, Agata; Lausen, Birgitte

    2014-01-01

    Objectives: To investigate association of host genomic variation and risk of infections during treatment for childhood acute lymphoblastic leukaemia (ALL). Methods: We explored association of 34 000 singlenucleotide polymorphisms (SNPs) related primarily to pharmacogenomics and immune function...

  9. seasonal variation in water quality of orle river basin, sw nigeria.

    African Journals Online (AJOL)

    LUCY

    The seasonal variation of water quality of Orle River and its tributatries in S.W. Nigeria was investigated forthnightly or two ... KEYWORD: water quality, river basin, wet and dry seasons; pollution. ..... Environmental Modeling and Software,.

  10. Nonlinear Variation of Parameters Formula for Impulsive Differential Equations with Initial Time Difference and Application

    Directory of Open Access Journals (Sweden)

    Peiguang Wang

    2014-01-01

    Full Text Available This paper establishes variation of parameters formula for impulsive differential equations with initial time difference. As an application, one of the results is used to investigate stability properties of solutions.

  11. Genetic Variation in Schizophrenia Liability is Shared With Intellectual Ability and Brain Structure

    NARCIS (Netherlands)

    Bohlken, Marc M; Brouwer, Rachel M; Mandl, René C W; Kahn, René S; Hulshoff Pol, Hilleke E

    2016-01-01

    BACKGROUND: Alterations in intellectual ability and brain structure are important genetic markers for schizophrenia liability. How variations in these phenotypes interact with variance in schizophrenia liability due to genetic or environmental factors is an area of active investigation. Studying

  12. Response variation in a batch of TLDS

    International Nuclear Information System (INIS)

    Burrage, J.; Campbell, A.

    2004-01-01

    Full text: At Royal Perth Hospital, LiF thermoluminescent dosimeter rods (TLDs) are handled in batches of 50. Rods in each batch are always annealed together to ensure the same thermal history and an individual batch is used with the same type and energy of radiation. A subset of a batch is used for calibration purposes by exposing them to a range of known doses and their output is used to calculate the dose received by other rods used for a dose measurement. Variation in TLD response is addressed by calculating 95% certainty levels from the calibration rods and applying this to the dose measurement rods. This approach relies on the sensitivity of rods within each batch being similar. This work investigates the validity of this assumption and considers possible benefits of applying individual rod sensitivities. The variation in response of TLD rods was assessed using 25 TLD-100 rods (Harshaw/Bicron) which were uniformly exposed to 1 Gy using 6 MeV photons in a linear accelerator on 5 separate occasions. Rods were read with a Harshaw 5500 reader. During the read process the Harshaw reader periodically checks for noise and PMT gain drift and the data were corrected for these parameters. Replicate exposure data were analysed using 1-way Analysis of Variance (ANOVA) to determine whether the between rod variations were significantly different to the variations within a single rod. A batch of 50 rods was also exposed on three occasions using the above technique. Individual TLD rod sensitivity values were determined using the rod responses from 2 exposures and these values were applied to correct charges on a rod-by-rod basis for the third exposure. ANOVA results on the 5 exposures of 25 rods showed the variance between rods was significantly greater than the within rod variance (p < 0.001). The precision of an individual rod was estimated to have a standard deviation of 2.8%. This suggests that the 95% confidence limits for repeated measurements using the same dose and

  13. Helicopter Acoustic Flight Test with Altitude Variation and Maneuvers

    Science.gov (United States)

    Watts, Michael E.; Greenwood, Eric; Sim, Ben; Stephenson, James; Smith, Charles D.

    2016-01-01

    A cooperative flight test campaign between NASA and the U.S. Army was performed from September 2014 to February 2015. The purposes of the testing were to: investigate the effects of altitude variation on noise generation, investigate the effects of gross weight variation on noise generation, establish the statistical variability in acoustic flight testing of helicopters, and characterize the effects of transient maneuvers on radiated noise for a medium-lift utility helicopter. This test was performed at three test sites (0, 4000, and 7000 feet above mean sea level) with two aircraft (AS350 SD1 and EH-60L) tested at each site. This report provides an overview of the test, documents the data acquired and describes the formats of the stored data.

  14. Procedural facade variations from a single layout

    KAUST Repository

    Bao, Fan

    2013-02-19

    We introduce a framework to generate many variations of a facade design that look similar to a given facade layout. Starting from an input image, the facade is hierarchically segmented and labeled with a collection of manual and automatic tools. The user can then model constraints that should be maintained in any variation of the input facade design. Subsequently, facade variations are generated for different facade sizes, where multiple variations can be produced for a certain size. Computing such new facade variations has many unique challenges, and we propose a new algorithm based on interleaving heuristic search and quadratic programming. In contrast to most previous work, we focus on the generation of new design variations and not on the automatic analysis of the input\\'s structure. Adding a modeling step with the user in the loop ensures that our results routinely are of high quality. © 2013 ACM.

  15. Procedural facade variations from a single layout

    KAUST Repository

    Bao, Fan; Schwarz, Michael; Wonka, Peter

    2013-01-01

    We introduce a framework to generate many variations of a facade design that look similar to a given facade layout. Starting from an input image, the facade is hierarchically segmented and labeled with a collection of manual and automatic tools. The user can then model constraints that should be maintained in any variation of the input facade design. Subsequently, facade variations are generated for different facade sizes, where multiple variations can be produced for a certain size. Computing such new facade variations has many unique challenges, and we propose a new algorithm based on interleaving heuristic search and quadratic programming. In contrast to most previous work, we focus on the generation of new design variations and not on the automatic analysis of the input's structure. Adding a modeling step with the user in the loop ensures that our results routinely are of high quality. © 2013 ACM.

  16. Interlanguage Variation: A Point Missed?

    Science.gov (United States)

    Tice, Bradley Scott

    A study investigated patterns in phonological errors occurring in the speaker's second language in both formal and informal speaking situations. Subjects were three adult learners of English as a second language, including a native Spanish-speaker and two Asians. Their speech was recorded during diagnostic testing (formal speech) and in everyday…

  17. MONTHLY VARIATION OF THE PHYSICOCHEMICAL ...

    African Journals Online (AJOL)

    The pH values of the effluent ranged between 4.0-7.8. For most part of the year the pH values were less than 5, suggesting that the effluent is generally slightly acidic. Based on analysis of data acquired, the investigation concluded that effluents from Rimco industries are polluting the Akwu Uru area of Nnewi with ...

  18. Stem anatomy variation in cottonwood

    Science.gov (United States)

    A.N. Foulger; J. Hacskaylo

    1968-01-01

    Investigations of mineral nutrient-tree growth relationships have dealt mainly with associations involving foliage composition, root formation, or volume production of wood. Few studies have been concerned with changes in wood anatomy associated with element deficiency. In 1949 Davis reported that calcium deficiency was accompanied by a reduction of primary tissue and...

  19. Spatial Distribution and Semiannual Variation of Cold-Dense Plasma Sheet

    Science.gov (United States)

    Bai, Shichen; Shi, Quanqi; Tian, Anmin; Nowada, Motoharu; Degeling, Alexander W.; Zhou, Xu-Zhi; Zong, Qiu-Gang; Rae, I. Jonathan; Fu, Suiyan; Zhang, Hui; Pu, Zuyin; Fazakerly, Andrew N.

    2018-01-01

    The cold-dense plasma sheet (CDPS) plays an important role in the entry process of the solar wind plasma into the magnetosphere. Investigating the seasonal variation of CDPS occurrences will help us better understand the long-term variation of plasma exchange between the solar wind and magnetosphere, but any seasonal variation of CDPS occurrences has not yet been reported in the literature. In this paper, we investigate the seasonal variation of the occurrence rate of CDPS using Geotail data from 1996 to 2015 and find a semiannual variation of the CDPS occurrences. Given the higher probability of solar wind entry under stronger northward interplanetary magnetic field (IMF) conditions, 20 years of IMF data (1996-2015) are used to investigate the seasonal variation of IMF Bz under northward IMF conditions. We find a semiannual variation of IMF Bz, which is consistent with the Russell-McPherron (R-M) effect. We therefore suggest that the semiannual variation of CDPS may be related to the R-M effect.

  20. HGVA: the Human Genome Variation Archive

    OpenAIRE

    Lopez, Javier; Coll, Jacobo; Haimel, Matthias; Kandasamy, Swaathi; Tarraga, Joaquin; Furio-Tari, Pedro; Bari, Wasim; Bleda, Marta; Rueda, Antonio; Gr?f, Stefan; Rendon, Augusto; Dopazo, Joaquin; Medina, Ignacio

    2017-01-01

    Abstract High-profile genomic variation projects like the 1000 Genomes project or the Exome Aggregation Consortium, are generating a wealth of human genomic variation knowledge which can be used as an essential reference for identifying disease-causing genotypes. However, accessing these data, contrasting the various studies and integrating those data in downstream analyses remains cumbersome. The Human Genome Variation Archive (HGVA) tackles these challenges and facilitates access to genomic...

  1. Temporal correlation in the Goldberg variations

    OpenAIRE

    Chestopal, Victor

    2010-01-01

    An interpreter of the Goldberg Variations is almost completely deprived of such utterly important guidance as the composer's tempo markings, which are as rare in the Goldberg Variations as they are in the other works of Bach. The final goal of my study is to suggest a logical foundation, upon which an interpreter of the Goldberg Variations can make his/her choice of tempi. Upon the analysis of opus's structure, which reveals an impressive panorama of symmetries, I suggest a multilevel system ...

  2. Regional variation in short distance homogamy

    OpenAIRE

    Haandrikman, Karen; van Wissen, Leo

    2011-01-01

    A third of all Dutch cohabiters choose a partner from the same municipality, so-called short distance homogamy. This article analyses the regional variation in this phenomenon, and it explains this variation in terms of geographical, socioeconomic, demographic and cultural determinants. Population register data on all new cohabiters in 2004 were used. Regression methods were employed to explain spatial patterns. Regional variation in short distance homogamy is largely explained by geographica...

  3. Temporal variation of clear-water scour at compound Abutments

    OpenAIRE

    Aminuddin Ab. Ghani; Reza Mohammadpour

    2016-01-01

    Most of actual abutments in rivers are built on foundation, while there is limited number of study available on the effects of the foundation on the local scour. In this study, temporal variation of local scour around compound abutment was investigated experimentally under clear-water conditions. The results showed that a suitable level of foundation is able to decrease the scour depth and increase scour time during the flood events. The trend of temporal scour depth at compound pier and abut...

  4. Variational method for magnetic impurities in metals: impurity pairs

    Energy Technology Data Exchange (ETDEWEB)

    Oles, A M [Max-Planck-Institut fuer Festkoerperforschung, Stuttgart (Germany, F.R.); Chao, K A [Linkoeping Univ. (Sweden). Dept. of Physics and Measurement Technology

    1980-01-01

    Applying a variational method to the generalized Wolff model, we have investigated the effect of impurity-impurity interaction on the formation of local moments in the ground state. The direct coupling between the impurities is found to be more important than the interaction between the impurities and the host conduction electrons, as far as the formation of local moments is concerned. Under certain conditions we also observe different valences on different impurities.

  5. Some new mathematical methods for variational objective analysis

    Science.gov (United States)

    Wahba, Grace; Johnson, Donald R.

    1994-01-01

    Numerous results were obtained relevant to remote sensing, variational objective analysis, and data assimilation. A list of publications relevant in whole or in part is attached. The principal investigator gave many invited lectures, disseminating the results to the meteorological community as well as the statistical community. A list of invited lectures at meetings is attached, as well as a list of departmental colloquia at various universities and institutes.

  6. Molecular Darwinism: The Contingency of Spontaneous Genetic Variation

    OpenAIRE

    Arber, Werner

    2011-01-01

    The availability of spontaneously occurring genetic variants is an important driving force of biological evolution. Largely thanks to experimental investigations by microbial geneticists, we know today that several different molecular mechanisms contribute to the overall genetic variations. These mechanisms can be assigned to three natural strategies to generate genetic variants: 1) local sequence changes, 2) intragenomic reshuffling of DNA segments, and 3) acquisition of a segment of foreign...

  7. Positive and negative variations in capacitive images for given defects under varying experimental conditions

    Science.gov (United States)

    Li, Chen; Yin, Xiaokang; Li, Zhen; Li, Wei; Chen, Guoming

    2018-04-01

    Capacitive imaging (CI) technique is a novel electromagnetic NDE technique. The Quasi-static electromagnetic field from the carefully designed electrode pair will vary when the electrical properties of the sample change, leading to the possibility of imaging. It is observed that for a given specimen, the targeted features appear as different variations in capacitive images under different experimental conditions. In some cases, even opposite variations occur, which brings confusion to indication interpretation. It is thus thought interesting to embark on investigations into the cause and effects of the negative variation phenomenon. In this work, the positive and negative variations were first explained from the measurement sensitivity distribution perspective. This was then followed by a detailed analysis using finite element models in COMSOL. A parametric experimental study on a glass fiber composite plate with artificial defects was then carried out to investigate how the experimental conditions affect the variation.

  8. Extensive Variation in Chromatin States Across Humans

    KAUST Repository

    Kasowski, M.

    2013-10-17

    The majority of disease-associated variants lie outside protein-coding regions, suggesting a link between variation in regulatory regions and disease predisposition. We studied differences in chromatin states using five histone modifications, cohesin, and CTCF in lymphoblastoid lines from 19 individuals of diverse ancestry. We found extensive signal variation in regulatory regions, which often switch between active and repressed states across individuals. Enhancer activity is particularly diverse among individuals, whereas gene expression remains relatively stable. Chromatin variability shows genetic inheritance in trios, correlates with genetic variation and population divergence, and is associated with disruptions of transcription factor binding motifs. Overall, our results provide insights into chromatin variation among humans.

  9. The circadian variation of premature atrial contractions

    DEFF Research Database (Denmark)

    Larsen, Bjørn Strøier; Kumarathurai, Preman; Nielsen, Olav W

    2016-01-01

    AIMS: The aim of the study was to assess a possible circadian variation of premature atrial contractions (PACs) in a community-based population and to determine if the daily variation could be used to assess a more vulnerable period of PACs in predicting later incidence of atrial fibrillation (AF...... variation in heart rate. After adjusting for relevant risk factors, the risk of AF was equal in all time intervals throughout the day. CONCLUSION: Premature atrial contractions showed a circadian variation in subjects with frequent PACs. No specific time interval of the day was more predictive of AF than...

  10. Extensive Variation in Chromatin States Across Humans

    KAUST Repository

    Kasowski, M.; Kyriazopoulou-Panagiotopoulou, S.; Grubert, F.; Zaugg, J. B.; Kundaje, A.; Liu, Y.; Boyle, A. P.; Zhang, Q. C.; Zakharia, F.; Spacek, D. V.; Li, J.; Xie, D.; Olarerin-George, A.; Steinmetz, L. M.; Hogenesch, J. B.; Kellis, M.; Batzoglou, S.; Snyder, M.

    2013-01-01

    The majority of disease-associated variants lie outside protein-coding regions, suggesting a link between variation in regulatory regions and disease predisposition. We studied differences in chromatin states using five histone modifications, cohesin, and CTCF in lymphoblastoid lines from 19 individuals of diverse ancestry. We found extensive signal variation in regulatory regions, which often switch between active and repressed states across individuals. Enhancer activity is particularly diverse among individuals, whereas gene expression remains relatively stable. Chromatin variability shows genetic inheritance in trios, correlates with genetic variation and population divergence, and is associated with disruptions of transcription factor binding motifs. Overall, our results provide insights into chromatin variation among humans.

  11. Factors influencing variation in dentist service rates.

    Science.gov (United States)

    Grembowski, D; Milgrom, P; Fiset, L

    1990-01-01

    In the previous article, we calculated dentist service rates for 200 general dentists based on a homogeneous, well-educated, upper-middle-class population of patients. Wide variations in the rates were detected. In this analysis, factors influencing variation in the rates were identified. Variation in rates for categories of dental services was explained by practice characteristics, patient exposure to fluoridated water supplies, and non-price competition in the dental market. Rates were greatest in large, busy practices in markets with high fees. Older practices consistently had lower rates across services. As a whole, these variables explained between 5 and 30 percent of the variation in the rates.

  12. [Influence of a variation potential on photosynthesis in pumpkin seedlings (Cucurbita pepo L.)].

    Science.gov (United States)

    Sukhov, V S; Shesterneva, O N; Surova, L M; Rumiantsev, E A; Vodeneev, V A

    2013-01-01

    The influence of a variation potential on photosynthesis in pumpkin seedlings (Cucurbita pepo L.) was investigated in our work. It was shown that the variation potential induced by cotyledon burning propagates into a leaf. It decreases CO2 assimilation and transpiration as well as increases nonphotochemical quenching. Investigation of isolated chloroplasts showed that lowering of the pH in incubation medium from 6.9-7.2 to 6.5 increases nonphotochemical quenching. It was proposed that lowering of the cytoplasmic pH induced by the variation potential takes place in the photosynthetic response development.

  13. Frequency variations of discrete cranial traits in major human populations. III. Hyperostotic variations.

    Science.gov (United States)

    Hanihara, T; Ishida, H

    2001-09-01

    Seven discrete cranial traits usually categorised as hyperostotic characters, the medial palatine canal, hypoglossal canal bridging, precondylar tubercle, condylus tertius, jugular foramen bridging, auditory exostosis, and mylohyoid bridging were investigated in 81 major human population samples from around the world. Significant asymmetric occurrences of the bilateral traits were detected in the medial palatine canal and jugular foramen bridging in several samples. Significant intertrait associations were found between some pairs of the traits, but not consistently across the large geographical samples. The auditory exostosis showed a predominant occurrence in males. With the exception of the auditory exostosis and mylohyoid bridging in a few samples, significant sex differences were slight. The frequency distributions of the traits (except for the auditory exostosis) showed some interregional clinality and intraregional discontinuity, suggesting that genetic drift could have contributed to the observed pattern of variation.

  14. Gravity and Height Variations at Medicina, Italy

    Science.gov (United States)

    Bruni, Sara; Zerbini, Susanna; Errico, Maddalena; Santi, Efisio; Wziontek, Hartmut

    2017-04-01

    Since 1996, at the Medicina station, height and gravity variations are monitored continuously by means of GPS, VLBI and superconducting gravimeter (SG) data. Additionally, absolute gravity observations are performed twice a year and environmental parameters, among others water table levels, are regularly acquired. Levelling between the different monuments at the site area is also carried out repeatedly to constrain local ties in the vertical position. Two GPS systems are located very close to each other, and both are in close proximity to the VLBI antenna. Twenty years of data are now available, which allow investigating both long- and short-period height and gravity signals together with their relevant correlations. Natural land subsidence, which is well known to occur in the area, is a major component of the observed long-term behavior; however, non-linear long-period signatures are also present in the time series. On a shorter time scale, fingerprints of the water table seasonal oscillations can be recognized in the data. The Medicina site is characterized by clayey soil subjected to consolidation effects when the water table lowers during summer periods. The pillar on which the SG is installed is especially affected because of its shallow foundation, causing height decreases in the order of 2.5-3 cm for water table lowering of 2 m. This study presents a comparative analysis of the different data sets with the aim of separating mass and deformation contributions in the SG gravity record.

  15. Process variation in electron beam sterilization

    International Nuclear Information System (INIS)

    Beck, Jeffrey A.

    2012-01-01

    The qualification and control of electron beam sterilization can be improved by the application of proven statistical analysis techniques such as Analysis of Variance (ANOVA) and Statistical Tolerance Limits. These statistical techniques can be useful tools in: •Locating and quantifying the minimum and maximum absorbed dose in a product. •Estimating the expected process maximum dose, given a minimum sterilizing dose. •Setting a process minimum dose target, based on an allowance for random measurement and process variation. •Determining the dose relationship between a reference dosimeter and process minimum and maximum doses. This study investigates and demonstrates the application of these tools in qualifying electron beam sterilization, and compares the conclusions obtained with those obtained using practices recommended in Guide for Process Control in Radiation Sterilization. The study supports the following conclusions for electron beam processes: 1.ANOVA is a more effective tool for evaluating the equivalency of absorbed doses than methods suggested in . 2.Process limits computed using statistical tolerance limits more accurately reflect actual process variability than the AAMI method, which applies +/−2 sample standard deviations (s) regardless of sample size. 3.The use of reference dose ratios lends itself to qualification using statistical tolerance limits. The current AAMI recommended approach may result in an overly optimistic estimate of the reference dose adjustment factor, as it is based on application of +/−2(s) tolerances regardless of sample size.

  16. Genetic basis of metabolome variation in yeast.

    Directory of Open Access Journals (Sweden)

    Jeffrey S Breunig

    2014-03-01

    Full Text Available Metabolism, the conversion of nutrients into usable energy and biochemical building blocks, is an essential feature of all cells. The genetic factors responsible for inter-individual metabolic variability remain poorly understood. To investigate genetic causes of metabolome variation, we measured the concentrations of 74 metabolites across ~ 100 segregants from a Saccharomyces cerevisiae cross by liquid chromatography-tandem mass spectrometry. We found 52 quantitative trait loci for 34 metabolites. These included linkages due to overt changes in metabolic genes, e.g., linking pyrimidine intermediates to the deletion of ura3. They also included linkages not directly related to metabolic enzymes, such as those for five central carbon metabolites to ira2, a Ras/PKA pathway regulator, and for the metabolites, S-adenosyl-methionine and S-adenosyl-homocysteine to slt2, a MAP kinase involved in cell wall integrity. The variant of ira2 that elevates metabolite levels also increases glucose uptake and ethanol secretion. These results highlight specific examples of genetic variability, including in genes without prior known metabolic regulatory function, that impact yeast metabolism.

  17. Ethnic variation in rhegmatogenous retinal detachments

    Science.gov (United States)

    Chandra, A; Banerjee, P; Davis, D; Charteris, D

    2015-01-01

    Purpose We aimed to investigate the clinical variation of rhegmatogenous retinal detachments (RD) in patients of different ethnicities. Methods Patients presenting with a primary RD from two ethnic groups were recruited from our tertiary referral hospital between August 2010 and December 2012. Patients who self-reported their ethnic origin either as European Caucasian (EC) or South Asian (SA) were included. Exclusion criteria included trauma, previous vitreoretinal procedures, age under 18 years, complicated cataract surgery and the presence of syndromes known to be associated with a high prevalence of RD. Detailed phenotypic data were collected. Descriptive and comparative statistical analyses were undertaken. Results 1269 Patients were recruited. 1173 (92.4%) were EC. Mean age of onset was 58.3 years (EC) and 54.5 years (SA) (P=0.006). 75.3% EC and 58.4% SA were phakic (Plattice retinal degeneration in the affected eye (P=0.003). Refractive myopia was greater in SA patients (mean: −6.1DS) than EC (−4.2DS) (P=0.032). Additionally, SA patients had a greater mean axial length (25.65 mm) than EC (25.06 mm) (P=0.014). No differences were demonstrated in laterality, family history, type of retinal break or macular status. Conclusions SA patients present with RD at an earlier age and have a more severe phenotype than ECs. Future management strategies for RD may need to reflect these differences. PMID:25853394

  18. Effects of temperature variation on MOSFET dosimetry

    International Nuclear Information System (INIS)

    Cheung Tsang; Butson, Martin J; Yu, Peter K N

    2004-01-01

    This note investigates temperature effects on dosimetry using a metal oxide semiconductor field effect transistor (MOSFET) for radiotherapy x-ray treatment. This was performed by analysing the dose response and threshold voltage outputs for MOSFET dosimeters as a function of ambient temperature. Results have shown that the clinical semiconductor dosimetry system (CSDS) MOSFET provides stable dose measurements with temperatures varying from 15 deg. C up to 40 deg. C. Thus standard irradiations performed at room temperature can be directly compared to in vivo dose assessments performed at near body temperature without a temperature correction function. The MOSFET dosimeter threshold voltage varies with temperature and this level is dependent on the dose history of the MOSFET dosimeter. However, the variation can be accounted for in the measurement method. For accurate dosimetry, the detector should be placed for approximately 60 s on a patient to allow thermal equilibrium before measurements are taken with the final reading performed whilst still attached to the patient or conversely left for approximately 120 s after removal from the patient if initial readout was measured at room temperature to allow temperature equilibrium to be established. (note)

  19. Factors influencing individual variation in perceptual directional microphone benefit.

    Science.gov (United States)

    Keidser, Gitte; Dillon, Harvey; Convery, Elizabeth; Mejia, Jorge

    2013-01-01

    Large variations in perceptual directional microphone benefit, which far exceed the variation expected from physical performance measures of directional microphones, have been reported in the literature. The cause for the individual variation has not been systematically investigated. To determine the factors that are responsible for the individual variation in reported perceptual directional benefit. A correlational study. Physical performance measures of the directional microphones obtained after they had been fitted to individuals, cognitive abilities of individuals, and measurement errors were related to perceptual directional benefit scores. Fifty-nine hearing-impaired adults with varied degrees of hearing loss participated in the study. All participants were bilaterally fitted with a Motion behind-the-ear device (500 M, 501 SX, or 501 P) from Siemens according to the National Acoustic Laboratories' non-linear prescription, version two (NAL-NL2). Using the Bamford-Kowal-Bench (BKB) sentences, the perceptual directional benefit was obtained as the difference in speech reception threshold measured in babble noise (SRTn) with the devices in directional (fixed hypercardioid) and in omnidirectional mode. The SRTn measurements were repeated three times with each microphone mode. Physical performance measures of the directional microphone included the angle of the microphone ports to loudspeaker axis, the frequency range dominated by amplified sound, the in situ signal-to-noise ratio (SNR), and the in situ three-dimensional, articulation-index weighted directivity index (3D AI-DI). The cognitive tests included auditory selective attention, speed of processing, and working memory. Intraparticipant variation on the repeated SRTn's and the interparticipant variation on the average SRTn were used to determine the effect of measurement error. A multiple regression analysis was used to determine the effect of other factors. Measurement errors explained 52% of the variation

  20. Stochastic variational approach to minimum uncertainty states

    Energy Technology Data Exchange (ETDEWEB)

    Illuminati, F.; Viola, L. [Dipartimento di Fisica, Padova Univ. (Italy)

    1995-05-21

    We introduce a new variational characterization of Gaussian diffusion processes as minimum uncertainty states. We then define a variational method constrained by kinematics of diffusions and Schroedinger dynamics to seek states of local minimum uncertainty for general non-harmonic potentials. (author)

  1. Macroinvertebrate variation in endorheic depression wetlands in ...

    African Journals Online (AJOL)

    Aquatic macroinvertebrates are rarely used in wetland assessments due to their variation. However, in terms of biodiversity, these invertebrates form an important component of wetland fauna. Spatial and temporal variation of macroinvertebrate assemblages in endorheic depressions (locally referred to as 'pans') in ...

  2. Size variation in Middle Pleistocene humans.

    Science.gov (United States)

    Arsuaga, J L; Carretero, J M; Lorenzo, C; Gracia, A; Martínez, I; Bermúdez de Castro, J M; Carbonell, E

    1997-08-22

    It has been suggested that European Middle Pleistocene humans, Neandertals, and prehistoric modern humans had a greater sexual dimorphism than modern humans. Analysis of body size variation and cranial capacity variation in the large sample from the Sima de los Huesos site in Spain showed instead that the sexual dimorphism is comparable in Middle Pleistocene and modern populations.

  3. Variation principle for nonlinear wave propagation

    International Nuclear Information System (INIS)

    Watanabe, T.; Lee, Y.C.; Nishikawa, Kyoji; Hojo, H.; Yoshida, Y.

    1976-01-01

    Variation principle is derived which determines stationary nonlinear propagation of electrostatic waves in the self-consistent density profile. Example is given for lower-hybrid waves and the relation to the variation principle for the Lagrangian density of electromagnetic fluids is discussed

  4. Genetic variation in bovine milk fat composition

    NARCIS (Netherlands)

    Stoop, W.M.

    2009-01-01

    In her thesis, Stoop shows that there is considerable genetic variation in milk fat composition, which opens opportunities to improve milk fat composition by selective breeding. Short and medium chain fatty acids had high heritabilities, whereas variation due to herd (mainly feed effects) was

  5. Parkinson's disease and mitochondrial gene variations

    DEFF Research Database (Denmark)

    Andalib, Sasan; Vafaee, Manouchehr Seyedi; Gjedde, Albert

    2014-01-01

    Parkinson's disease (PD) is a common disorder of the central nervous system in the elderly. The pathogenesis of PD is a complex process, with genetics as an important contributing factor. This factor may stem from mitochondrial gene variations and mutations as well as from nuclear gene variations...

  6. Isozyme variation in wild and cultivated pineapple

    Science.gov (United States)

    Isozyme variation was studied in 161 accessions of pineapple including four species of Ananas and one of Pseudananas. Six enzyme systems (ADH, GPI, PGM, SKDH, TPI, UGPP) involving seven putative loci revealed 35 electromorphs . Considerable variation exists within and between species of Ananas. Sixt...

  7. Anatomy, Medical Education, and Human Ancestral Variation

    Science.gov (United States)

    Strkalj, Goran; Spocter, Muhammad A.; Wilkinson, A. Tracey

    2011-01-01

    It is argued in this article that the human body both in health and disease cannot be fully understood without adequately accounting for the different levels of human variation. The article focuses on variation due to ancestry, arguing that the inclusion of information pertaining to ancestry in human anatomy teaching materials and courses should…

  8. Ranking of Unwarranted Variations in Healthcare Treatments

    NARCIS (Netherlands)

    Moes, Herry; Brekelmans, Ruud; Hamers, Herbert; Hasaart, F.

    2017-01-01

    In this paper, we introduce a framework designed to identify and rank possible unwarranted variation of treatments in healthcare. The innovative aspect of this framework is a ranking procedure that aims to identify healthcare institutions where unwarranted variation is most severe, and diagnosis

  9. Genetic variation between ecotypic populations of Chloris ...

    African Journals Online (AJOL)

    Genetic variation between ecotypic populations of Chloris roxburghiana grass detected through RAPD analysis. ... frequency indicated that the four populations of C. roxburghiana were genetically distinct, probably as a result of variation in soil fertility, geographical isolation and socio-ecological history of the study sites.

  10. Genetic Variation in Cardiomyopathy and Cardiovascular Disorders.

    Science.gov (United States)

    McNally, Elizabeth M; Puckelwartz, Megan J

    2015-01-01

    With the wider deployment of massively-parallel, next-generation sequencing, it is now possible to survey human genome data for research and clinical purposes. The reduced cost of producing short-read sequencing has now shifted the burden to data analysis. Analysis of genome sequencing remains challenged by the complexity of the human genome, including redundancy and the repetitive nature of genome elements and the large amount of variation in individual genomes. Public databases of human genome sequences greatly facilitate interpretation of common and rare genetic variation, although linking database sequence information to detailed clinical information is limited by privacy and practical issues. Genetic variation is a rich source of knowledge for cardiovascular disease because many, if not all, cardiovascular disorders are highly heritable. The role of rare genetic variation in predicting risk and complications of cardiovascular diseases has been well established for hypertrophic and dilated cardiomyopathy, where the number of genes that are linked to these disorders is growing. Bolstered by family data, where genetic variants segregate with disease, rare variation can be linked to specific genetic variation that offers profound diagnostic information. Understanding genetic variation in cardiomyopathy is likely to help stratify forms of heart failure and guide therapy. Ultimately, genetic variation may be amenable to gene correction and gene editing strategies.

  11. A min-max variational principle

    International Nuclear Information System (INIS)

    Georgiev, P.G.

    1995-11-01

    In this paper a variational principle for min-max problems is proved that is of the same spirit as Deville-Godefroy-Zizler's variational principle for minimization problems. A localization theorem in which the mini-max points for the perturbed function with respect top a given ε-min-max point are localized is presented. 3 refs

  12. Regional variation in short distance homogamy

    NARCIS (Netherlands)

    Haandrikman, K.; van Wissen, L.J.G.

    2011-01-01

    A third of all Dutch cohabiters choose a partner from the same municipality, so-called short distance homogamy. This article analyses the regional variation in this phenomenon, and it explains this variation in terms of geographical, socioeconomic, demographic and cultural determinants. Population

  13. Atlas of temporal variations - interdisciplinary scientific work

    Science.gov (United States)

    Gamburtsev, A. G.; Oleinik, O. V.

    2003-04-01

    The year 2002 will culminate in the publication of the third volume of the fundamental interdisciplinary work "Atlas of Temporal Variations in Natural, Anthropogenic and Social Processes", which now will comprise three volumes (1994, 1998, 2002). The Atlas has pooled the information on the main peculiarities of processes' behaviour in various natural and humanitarian spheres over the widest temporal and spatial range. The main scientific goal of the work consists in discovering the behaviour pattern of natural, anthropogenic and social processes and the cause and effect links between them. Thus, the Atlas contains extensive comparative generalisation from the vastly different data. For one thing, it is a fundamental work on the law-governed nature of evolution in natural and social spheres; for another, it can be used as a reference book and valuable source of information for research in different directions. The authors seek to treat every piece of information as part of an integrated whole. When analysing the data, we operate on the premise that surrounding nature, society and their elements are open dynamic systems. Systems of this kind exhibit non-linear characteristics and a tendency towards ordered and chaotic behaviour. These features are revealed in the course of the analysis of time series. The data processing procedures applied are unified, all processes being generally expressed in terms of their time series and time-spectral diagrams. The technique is aimed at determination of investigated parameters' rhythms and the analysis of their evolution. This approach enables us to show the dynamics of processes occurring in absolutely dissimilar objects and performs their comparative analysis, with particular emphasis placed on rhythms and trends. As a result successions of illustrations are obtained and formed the basis of the Atlas. The Atlas covers processes that occur in objects belonging to the lithosphere, atmosphere, hydrosphere and social sphere as well

  14. Variation in radiographic protocols in paediatric interventional cardiology

    International Nuclear Information System (INIS)

    McFadden, S L; Hughes, C M; Winder, R J

    2013-01-01

    The aim of this work is to determine current radiographic protocols in paediatric interventional cardiology (IC) in the UK and Ireland. To do this we investigated which imaging parameters/protocols are commonly used in IC in different hospitals, to identify if a standard technique is used and illustrate any variation in practice. A questionnaire was sent to all hospitals in the UK and Ireland which perform paediatric IC to obtain information on techniques used in each clinical department and on the range of clinical examinations performed. Ethical and research governance approval was sought from the Office for Research Ethics Committees Northern Ireland and the individual trusts. A response rate of 79% was achieved, and a wide variation in technique was found between hospitals. The main differences in technique involved variations in the use of an anti-scatter grid and the use of additional filtration to the radiation beam, frame rates for digital acquisition and pre-programmed projections/paediatric specific programming in the equipment. We conclude that there is no standard protocol for carrying out paediatric IC in the UK or Ireland. Each hospital carries out the IC procedure according to its own local protocols resulting in a wide variation in radiation dose. (paper)

  15. Variations in Transverse Foramina of Cervical Vertebrae: Morphology & Clinical Importance

    Directory of Open Access Journals (Sweden)

    Vaishakhi Gonsai

    2015-12-01

    Full Text Available Background: The purpose of this study is to investigate variations in transverse foramina in the cervical vertebrae and its morphological and clinical importance. Materials and Method : The variations in the number and size of transverse foramina was studied in total 200 human dried cervical vertebrae, which were taken from the Department of Anatomy, B.J.Medical College, Ahmedabad. All the vertebrae were observed for variation in number and size of transverse foramina. Results: Out of 200 cervical vertebrae, complete double transverse foramina were observed in 40 vertebrae (20%, among them unilateral double foramina were found in 31 vertebrae (15.5% and the bilateral double foramina were found in 9 vertebrae (4.5%. Incomplete double transverse foramina were observed in 22 vertebrae (11%, among them unilateral double foramina were found in 16 vertebrae (8% and bilateral double foramina were observed in 6 vertebrae (3%. Conclusion: Complete unilateral double transverse foramina of cervical vertebrae were more common than bilateral. Also unilateral small size transverse foramina of cervical vertebrae were also common. This variation is important for the neurosurgeon during cervical surgery. Under such condition the course of the vertebral artery may be distorted. It is also useful for Radiologist during CT and MRI scan.

  16. Genomics technologies to study structural variations in the grapevine genome

    Directory of Open Access Journals (Sweden)

    Cardone Maria Francesca

    2016-01-01

    Full Text Available Grapevine is one of the most important crop plants in the world. Recently there was great expansion of genomics resources about grapevine genome, thus providing increasing efforts for molecular breeding. Current cultivars display a great level of inter-specific differentiation that needs to be investigated to reach a comprehensive understanding of the genetic basis of phenotypic differences, and to find responsible genes selected by cross breeding programs. While there have been significant advances in resolving the pattern and nature of single nucleotide polymorphisms (SNPs on plant genomes, few data are available on copy number variation (CNV. Furthermore association between structural variations and phenotypes has been described in only a few cases. We combined high throughput biotechnologies and bioinformatics tools, to reveal the first inter-varietal atlas of structural variation (SV for the grapevine genome. We sequenced and compared four table grape cultivars with the Pinot noir inbred line PN40024 genome as the reference. We detected roughly 8% of the grapevine genome affected by genomic variations. Taken into account phenotypic differences existing among the studied varieties we performed comparison of SVs among them and the reference and next we performed an in-depth analysis of gene content of polymorphic regions. This allowed us to identify genes showing differences in copy number as putative functional candidates for important traits in grapevine cultivation.

  17. Variation in radiographic protocols in paediatric interventional cardiology.

    Science.gov (United States)

    McFadden, S L; Hughes, C M; Winder, R J

    2013-06-01

    The aim of this work is to determine current radiographic protocols in paediatric interventional cardiology (IC) in the UK and Ireland. To do this we investigated which imaging parameters/protocols are commonly used in IC in different hospitals, to identify if a standard technique is used and illustrate any variation in practice. A questionnaire was sent to all hospitals in the UK and Ireland which perform paediatric IC to obtain information on techniques used in each clinical department and on the range of clinical examinations performed. Ethical and research governance approval was sought from the Office for Research Ethics Committees Northern Ireland and the individual trusts. A response rate of 79% was achieved, and a wide variation in technique was found between hospitals. The main differences in technique involved variations in the use of an anti-scatter grid and the use of additional filtration to the radiation beam, frame rates for digital acquisition and pre-programmed projections/paediatric specific programming in the equipment. We conclude that there is no standard protocol for carrying out paediatric IC in the UK or Ireland. Each hospital carries out the IC procedure according to its own local protocols resulting in a wide variation in radiation dose.

  18. Albedo matters: Understanding runaway albedo variations on Pluto

    Science.gov (United States)

    Earle, Alissa M.; Binzel, Richard P.; Young, Leslie A.; Stern, S. A.; Ennico, K.; Grundy, W.; Olkin, C. B.; Weaver, H. A.; New Horizons Surface Composition Theme

    2018-03-01

    The data returned from NASA's New Horizons reconnaissance of the Pluto system show striking albedo variations from polar to equatorial latitudes as well as sharp longitudinal boundaries. Pluto has a high obliquity (currently 119°) that varies by 23° over a period of less than 3 million years. This variation, combined with its regressing longitude of perihelion (360° over 3.7 million years), creates epochs of "Super Seasons" where one pole is pointed at the Sun at perihelion, thereby experiencing a short, relatively warm summer followed by its longest possible period of winter darkness. In contrast, the other pole experiences a much longer, less intense summer and a short winter season. We use a simple volatile sublimation and deposition model to explore the relationship between albedo variations, latitude, and volatile sublimation and deposition for the current epoch as well as historical epochs during which Pluto experienced these "Super Seasons." Our investigation quantitatively shows that Pluto's geometry creates the potential for runaway albedo and volatile variations, particularly in the equatorial region, which can sustain stark longitudinal contrasts like the ones we see between Tombaugh Regio and the informally named Cthulhu Regio.

  19. Characterising phase variations in MALDI-TOF data and correcting

    Directory of Open Access Journals (Sweden)

    Michael C Fitzgerald

    2005-01-01

    Full Text Available Abstract: The use of MALDI-TOF mass spectrometry as a means of analyzing the proteome has been evaluated extensively in recent years. One of the limitations of this technique that has impeded the development of robust data analysis algorithms is the variability in the location of protein ion signals along the x-axis. We studied technical variations of MALDI-TOF measurements in the context of proteomics profiling. By acquiring a benchmark data set with five replicates, we estimated 76% to 85% of the total variance is due to phase variation. We devised a lobster plot, so named because of the resemblance to a lobster claw, to help detect the phase variation in replicates. We also investigated a peak alignment algorithm to remove the phase variation. This operation is analogous to the normalization step in microarray data analysis. Only after this critical step can features of biological interest be clearly revealed. With the help of principal component analysis, we demonstrated that after peak alignment, the differences among replicates are reduced. We compared this approach to peak alignment with a model-based calibration approach in which there was known information about peaks in common among all spectra. Finally, we examined the potential value at each point in an analysis pipeline of having a set of methods available that includes parametric, semiparametric and nonparametric methods; among such methods are those that benefit from the use of prior information.

  20. Spiral phyllotaxis underlies constrained variation in Anemone (Ranunculaceae) tepal arrangement.

    Science.gov (United States)

    Kitazawa, Miho S; Fujimoto, Koichi

    2018-05-01

    Stabilization and variation of floral structures are indispensable for plant reproduction and evolution; however, the developmental mechanism regulating their structural robustness is largely unknown. To investigate this mechanism, we examined positional arrangement (aestivation) of excessively produced perianth organs (tepals) of six- and seven-tepaled (lobed) flowers in six Anemone species (Ranunculaceae). We found that the tepal arrangement that occurred in nature varied intraspecifically between spiral and whorled arrangements. Moreover, among the studied species, variation was commonly limited to three types, including whorls, despite five geometrically possible arrangements in six-tepaled flowers and two types among six possibilities in seven-tepaled flowers. A spiral arrangement, on the other hand, was unique to five-tepaled flowers. A spiral phyllotaxis model with stochasticity on initiating excessive primordia accounted for these limited variations in arrangement in cases when the divergence angle between preexisting primordia was less than 144°. Moreover, interspecific differences in the frequency of the observed arrangements were explained by the change of model parameters that represent meristematic growth and differential organ growth. These findings suggest that the phyllotaxis parameters are responsible for not only intraspecific stability but interspecific difference of floral structure. Decreasing arrangements from six-tepaled to seven-tepaled Anemone flowers demonstrate that the stabilization occurs as development proceeds to increase the component (organ) number, in contrast from the intuition that the variation will be larger due to increasing number of possible states (arrangements).

  1. INTERNAL-CYCLE VARIATION OF SOLAR DIFFERENTIAL ROTATION

    International Nuclear Information System (INIS)

    Li, K. J.; Xie, J. L.; Shi, X. J.

    2013-01-01

    The latitudinal distributions of the yearly mean rotation rates measured by Suzuki in 1998 and 2012 and Pulkkinen and Tuominen in 1998 are utilized to investigate internal-cycle variation of solar differential rotation. The rotation rate at the solar equator seems to have decreased since cycle 10 onward. The coefficient B of solar differential rotation, which represents the latitudinal gradient of rotation, is found to be smaller in the several years after the minimum of a solar cycle than in the several years after the maximum time of the cycle, and it peaks several years after the maximum time of the solar cycle. The internal-cycle variation of the solar rotation rates looks similar in profile to that of the coefficient B. A new explanation is proposed to address such a solar-cycle-related variation of the solar rotation rates. Weak magnetic fields may more effectively reflect differentiation at low latitudes with high rotation rates than at high latitudes with low rotation rates, and strong magnetic fields may more effectively repress differentiation at relatively low latitudes than at high latitudes. The internal-cycle variation is inferred as the result of both the latitudinal migration of the surface torsional pattern and the repression of strong magnetic activity in differentiation.

  2. Observing the variation of asteroid thermal inertia with heliocentric distance

    Science.gov (United States)

    Rozitis, B.; Green, S. F.; MacLennan, E.; Emery, J. P.

    2018-06-01

    Thermal inertia is a useful property to characterize a planetary surface, since it can be used as a qualitative measure of the regolith grain size. It is expected to vary with heliocentric distance because of its dependence on temperature. However, no previous investigation has conclusively observed a change in thermal inertia for any given planetary body. We have addressed this by using NEOWISE data and the Advanced Thermophysical Model to study the thermophysical properties of the near-Earth asteroids (1036) Ganymed, (1580) Betulia, and (276 049) 2002 CE26 as they moved around their highly eccentric orbits. We confirm that the thermal inertia values of Ganymed and 2002 CE26 do vary with heliocentric distance, although the degree of variation observed depends on the spectral emissivity assumed in the thermophysical modelling. We also confirm that the thermal inertia of Betulia did not change for three different observations obtained at the same heliocentric distance. Depending on the spectral emissivity, the variations for Ganymed and 2002 CE26 are potentially more extreme than that implied by theoretical models of heat transfer within asteroidal regoliths, which might be explained by asteroids having thermal properties that also vary with depth. Accounting for this variation reduces a previously observed trend of decreasing asteroid thermal inertia with increasing size, and suggests that the surfaces of small and large asteroids could be much more similar than previously thought. Furthermore, this variation can affect Yarkovsky orbital drift predictions by a few tens of per cent.

  3. Genetically-based olfactory signatures persist despite dietary variation.

    Directory of Open Access Journals (Sweden)

    Jae Kwak

    Full Text Available Individual mice have a unique odor, or odortype, that facilitates individual recognition. Odortypes, like other phenotypes, can be influenced by genetic and environmental variation. The genetic influence derives in part from genes of the major histocompatibility complex (MHC. A major environmental influence is diet, which could obscure the genetic contribution to odortype. Because odortype stability is a prerequisite for individual recognition under normal behavioral conditions, we investigated whether MHC-determined urinary odortypes of inbred mice can be identified in the face of large diet-induced variation. Mice trained to discriminate urines from panels of mice that differed both in diet and MHC type found the diet odor more salient in generalization trials. Nevertheless, when mice were trained to discriminate mice with only MHC differences (but on the same diet, they recognized the MHC difference when tested with urines from mice on a different diet. This indicates that MHC odor profiles remain despite large dietary variation. Chemical analyses of urinary volatile organic compounds (VOCs extracted by solid phase microextraction (SPME and analyzed by gas chromatography/mass spectrometry (GC/MS are consistent with this inference. Although diet influenced VOC variation more than MHC, with algorithmic training (supervised classification MHC types could be accurately discriminated across different diets. Thus, although there are clear diet effects on urinary volatile profiles, they do not obscure MHC effects.

  4. Individual Variation in the Late Positive Complex to Semantic Anomalies

    Science.gov (United States)

    Kos, Miriam; van den Brink, Danielle; Hagoort, Peter

    2012-01-01

    It is well-known that, within ERP paradigms of sentence processing, semantically anomalous words elicit N400 effects. Less clear, however, is what happens after the N400. In some cases N400 effects are followed by Late Positive Complexes (LPC), whereas in other cases such effects are lacking. We investigated several factors which could affect the LPC, such as contextual constraint, inter-individual variation, and working memory. Seventy-two participants read sentences containing a semantic manipulation (Whipped cream tastes sweet/anxious and creamy). Neither contextual constraint nor working memory correlated with the LPC. Inter-individual variation played a substantial role in the elicitation of the LPC with about half of the participants showing a negative response and the other half showing an LPC. This individual variation correlated with a syntactic ERP as well as an alternative semantic manipulation. In conclusion, our results show that inter-individual variation plays a large role in the elicitation of the LPC and this may account for the diversity in LPC findings in language research. PMID:22973249

  5. Mechanism and modelling of source/drain asymmetry variation in 65 nm CMOS devices for SRAM and logic applications

    International Nuclear Information System (INIS)

    Lee, T H; Fang, Y K; Chiang, Y T; Lin, C T; Chen, M S; Cheng, O

    2008-01-01

    The source/drain asymmetry variation of 65 nm CMOS devices for SRAM and logic applications has been investigated in detail. For the first time, we observe that the asymmetry variation is proportional to the inverse of the root square of the device area. In other words, the asymmetry variation should become worse for future advanced CMOS technologies. Fortunately, through the T-CAD simulations and experiments, we find the variation can be improved significantly with the optimization of the poly-gate grain size, extra laser annealing and using a vertical profile poly-gate. Furthermore, the improvement in asymmetry variation leads to a better static noise margin of SRAM

  6. Variation Tolerant On-Chip Interconnects

    CERN Document Server

    Nigussie, Ethiopia Enideg

    2012-01-01

    This book presents design techniques, analysis and implementation of high performance and power efficient, variation tolerant on-chip interconnects.  Given the design paradigm shift to multi-core, interconnect-centric designs and the increase in sources of variability and their impact in sub-100nm technologies, this book will be an invaluable reference for anyone concerned with the design of next generation, high-performance electronics systems. Provides comprehensive, circuit-level explanation of high-performance, energy-efficient, variation-tolerant on-chip interconnect; Describes design techniques to mitigate problems caused by variation; Includes techniques for design and implementation of self-timed on-chip interconnect, delay variation insensitive communication protocols, high speed signaling techniques and circuits, bit-width independent completion detection and process, voltage and temperature variation tolerance.                          

  7. Variational theory of nuclear and neutron matter

    International Nuclear Information System (INIS)

    Pandharipande, V.R.; Wiringa, R.B.

    1989-06-01

    In these lectures we will discuss attempts to solve the A = 3 to ∞ nuclear many-body problems with the variational method. We choose the form of a variational wave function Χ v (1, 2 hor-ellipsis A) to describe the ground state. The Χ v and the ground-state energy E v are obtained by minimizing E v = left-angle Χ v |H|Χ v right-angle/left-angle Χ v |Χ v right-angle with respect to variations in Χ v . If the form of the variational wave function is chosen properly we can expect Χ v ∼ Χ 0 and E v ∼ E 0 where Χ 0 and E 0 are the exact ground-state wave function and energy. In general E v ≥ E 0 in variational calculations. 63 refs., 11 figs

  8. Techniques to assess biological variation in destructive data

    NARCIS (Netherlands)

    Tijskens, L.M.M.; Schouten, R.E.; Jongbloed, G.; Konopacki, P.J.

    2018-01-01

    Variation is present in all measured data, due to variation between individuals (biological variation) and variation induced by the measuring system (technical variation). Biological variation present in experimental data is not the result of a random process but strictly subject to deterministic

  9. Genome Variation Map: a data repository of genome variations in BIG Data Center

    OpenAIRE

    Song, Shuhui; Tian, Dongmei; Li, Cuiping; Tang, Bixia; Dong, Lili; Xiao, Jingfa; Bao, Yiming; Zhao, Wenming; He, Hang; Zhang, Zhang

    2017-01-01

    Abstract The Genome Variation Map (GVM; http://bigd.big.ac.cn/gvm/) is a public data repository of genome variations. As a core resource in the BIG Data Center, Beijing Institute of Genomics, Chinese Academy of Sciences, GVM dedicates to collect, integrate and visualize genome variations for a wide range of species, accepts submissions of different types of genome variations from all over the world and provides free open access to all publicly available data in support of worldwide research a...

  10. Some remarks on variational and quasi-variational inequalities of monotone operators

    International Nuclear Information System (INIS)

    Siddiqi, A.H.

    1990-08-01

    In this paper we study a fairly general class of variational and quasi-variational inequalities problem which represent some important physical phenomena. Several well-known results concerning variational inequalities are special cases of our results. Existence, uniqueness and numerical analysis of this problem have been studied. (author). 39 refs

  11. Fast Variations In Spectrum of Comet Halley

    Science.gov (United States)

    Borysenko, S. A.

    The goal of this work is to research fast variations of spectral lines intensities in spectra of comet Halley. The present research was made on the basis of more then 500 high- resolution spectrogram obtained by L.M. Shulman and H.K. Nazarchuk in November- December, 1985 at the 6-m telescope (SAO, Russia). Some fast variations with different quasiperiods were detected in all the spectrograms. Quasiperiods of these variations were from 15 - 40 min to 1.5 - 2 hours. As data from spacecraft "Vega-2" show, more fast variations with quasiperiods 5 - 10 min are obviously present in cometary time variations. Only the most important lines so as C2, C3, CN, CH and NH2 were analyzed. False periods were checked by comparison of the power spectra of the variations with the computed spectral window of the data. Only false periods about 400 sec (the avarage period of exposition) were detected. An algorithm for analysis of locally Poisson's time series was proposed. Two types of fast variations are detected: 1)high amplitude variations with more long quasiperiods (1.5 - 2 hours) and the coefficient of crosscorrelations between line intensities about 0.9 - 0.95; 2)low amplitude variations with short periods (15 - 40 min), which look like white noise and have the coefficient of crosscorrelations about 0.1 - 0.3. This difference may be caused by nature of variations. The first type variations may be an effect of both active processes in cometary nucleus and streams of solar protons. Analysis of solar proton flux variation with energies >1 MeV in November - Decem- ber 1985 confirms the above-mentioned version. In the second case it may by only inner processes in the nucleus that generate the observed variations. For determination of general parameters of cometary atmosphere, such as the produc- tion rates of radicals C2, C3, CN, CH, and NH2 it was necessary to estimate the contri- bution of dust grains luminiscence into the continuum of the comet. Space and wave- length distribution

  12. The impact of nectar chemical features on phenotypic variation in two related nectar yeasts.

    Science.gov (United States)

    Pozo, María I; Herrera, Carlos M; Van den Ende, Wim; Verstrepen, Kevin; Lievens, Bart; Jacquemyn, Hans

    2015-06-01

    Floral nectars become easily colonized by microbes, most often species of the ascomycetous yeast genus Metschnikowia. Although it is known that nectar composition can vary tremendously among plant species, most probably corresponding to the nutritional requirements of their main pollinators, far less is known about how variation in nectar chemistry affects intraspecific variation in nectarivorous yeasts. Because variation in nectar traits probably affects growth and abundance of nectar yeasts, nectar yeasts can be expected to display large phenotypic variation in order to cope with varying nectar conditions. To test this hypothesis, we related variation in the phenotypic landscape of a vast collection of nectar-living yeast isolates from two Metschnikowia species (M. reukaufii and M. gruessii) to nectar chemical traits using non-linear redundancy analyses. Nectar yeasts were collected from 19 plant species from different plant families to include as much variation in nectar chemical traits as possible. As expected, nectar yeasts displayed large variation in phenotypic traits, particularly in traits related to growth performance in carbon sources and inhibitors, which was significantly related to the host plant from which they were isolated. Total sugar concentration and relative fructose content significantly explained the observed variation in the phenotypic profile of the investigated yeast species, indicating that sugar concentration and composition are the key traits that affect phenotypic variation in nectarivorous yeasts. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  13. Influence of the variation potential on photosynthetic flows of light energy and electrons in pea.

    Science.gov (United States)

    Sukhova, Ekaterina; Mudrilov, Maxim; Vodeneev, Vladimir; Sukhov, Vladimir

    2018-05-01

    Local damage (mainly burning, heating, and mechanical wounding) induces propagation of electrical signals, namely, variation potentials, which are important signals during the life of plants that regulate different physiological processes, including photosynthesis. It is known that the variation potential decreases the rate of CO 2 assimilation by the Calvin-Benson cycle; however, its influence on light reactions has been poorly investigated. The aim of our work was to investigate the influence of the variation potential on the light energy flow that is absorbed, trapped and dissipated per active reaction centre in photosystem II and on the flow of electrons through the chloroplast electron transport chain. We analysed chlorophyll fluorescence in pea leaves using JIP-test and PAM-fluorometry; we also investigated delayed fluorescence. The electrical signals were registered using extracellular electrodes. We showed that the burning-induced variation potential stimulated a nonphotochemical loss of energy in photosystem II under dark conditions. It was also shown that the variation potential gradually increased the flow of light energy absorbed, trapped and dissipated by photosystem II. These changes were likely caused by an increase in the fraction of absorbed light distributed to photosystem II. In addition, the variation potential induced a transient increase in electron flow through the photosynthetic electron transport chain. Some probable mechanisms for the influence of the variation potential on the light reactions of photosynthesis (including the potential role of intracellular pH decrease) are discussed in the work.

  14. Determinants of inter-specific variation in basal metabolic rate.

    Science.gov (United States)

    White, Craig R; Kearney, Michael R

    2013-01-01

    Basal metabolic rate (BMR) is the rate of metabolism of a resting, postabsorptive, non-reproductive, adult bird or mammal, measured during the inactive circadian phase at a thermoneutral temperature. BMR is one of the most widely measured physiological traits, and data are available for over 1,200 species. With data available for such a wide range of species, BMR is a benchmark measurement in ecological and evolutionary physiology, and is often used as a reference against which other levels of metabolism are compared. Implicit in such comparisons is the assumption that BMR is invariant for a given species and that it therefore represents a stable point of comparison. However, BMR shows substantial variation between individuals, populations and species. Investigation of the ultimate (evolutionary) explanations for these differences remains an active area of inquiry, and explanation of size-related trends remains a contentious area. Whereas explanations for the scaling of BMR are generally mechanistic and claim ties to the first principles of chemistry and physics, investigations of mass-independent variation typically take an evolutionary perspective and have demonstrated that BMR is ultimately linked with a range of extrinsic variables including diet, habitat temperature, and net primary productivity. Here we review explanations for size-related and mass-independent variation in the BMR of animals, and suggest ways that the various explanations can be evaluated and integrated.

  15. Random matrix approach to the dynamics of stock inventory variations

    International Nuclear Information System (INIS)

    Zhou Weixing; Mu Guohua; Kertész, János

    2012-01-01

    It is well accepted that investors can be classified into groups owing to distinct trading strategies, which forms the basic assumption of many agent-based models for financial markets when agents are not zero-intelligent. However, empirical tests of these assumptions are still very rare due to the lack of order flow data. Here we adopt the order flow data of Chinese stocks to tackle this problem by investigating the dynamics of inventory variations for individual and institutional investors that contain rich information about the trading behavior of investors and have a crucial influence on price fluctuations. We find that the distributions of cross-correlation coefficient C ij have power-law forms in the bulk that are followed by exponential tails, and there are more positive coefficients than negative ones. In addition, it is more likely that two individuals or two institutions have a stronger inventory variation correlation than one individual and one institution. We find that the largest and the second largest eigenvalues (λ 1 and λ 2 ) of the correlation matrix cannot be explained by random matrix theory and the projections of investors' inventory variations on the first eigenvector u(λ 1 ) are linearly correlated with stock returns, where individual investors play a dominating role. The investors are classified into three categories based on the cross-correlation coefficients C VR between inventory variations and stock returns. A strong Granger causality is unveiled from stock returns to inventory variations, which means that a large proportion of individuals hold the reversing trading strategy and a small part of individuals hold the trending strategy. Our empirical findings have scientific significance in the understanding of investors' trading behavior and in the construction of agent-based models for emerging stock markets. (paper)

  16. Size Matters: Individual Variation in Ectotherm Growth and Asymptotic Size.

    Directory of Open Access Journals (Sweden)

    Richard B King

    Full Text Available Body size, and, by extension, growth has impacts on physiology, survival, attainment of sexual maturity, fecundity, generation time, and population dynamics, especially in ectotherm animals that often exhibit extensive growth following attainment of sexual maturity. Frequently, growth is analyzed at the population level, providing useful population mean growth parameters but ignoring individual variation that is also of ecological and evolutionary significance. Our long-term study of Lake Erie Watersnakes, Nerodia sipedon insularum, provides data sufficient for a detailed analysis of population and individual growth. We describe population mean growth separately for males and females based on size of known age individuals (847 captures of 769 males, 748 captures of 684 females and annual growth increments of individuals of unknown age (1,152 males, 730 females. We characterize individual variation in asymptotic size based on repeated measurements of 69 males and 71 females that were each captured in five to nine different years. The most striking result of our analyses is that asymptotic size varies dramatically among individuals, ranging from 631-820 mm snout-vent length in males and from 835-1125 mm in females. Because female fecundity increases with increasing body size, we explore the impact of individual variation in asymptotic size on lifetime reproductive success using a range of realistic estimates of annual survival. When all females commence reproduction at the same age, lifetime reproductive success is greatest for females with greater asymptotic size regardless of annual survival. But when reproduction is delayed in females with greater asymptotic size, lifetime reproductive success is greatest for females with lower asymptotic size when annual survival is low. Possible causes of individual variation in asymptotic size, including individual- and cohort-specific variation in size at birth and early growth, warrant further

  17. Size Matters: Individual Variation in Ectotherm Growth and Asymptotic Size

    Science.gov (United States)

    King, Richard B.

    2016-01-01

    Body size, and, by extension, growth has impacts on physiology, survival, attainment of sexual maturity, fecundity, generation time, and population dynamics, especially in ectotherm animals that often exhibit extensive growth following attainment of sexual maturity. Frequently, growth is analyzed at the population level, providing useful population mean growth parameters but ignoring individual variation that is also of ecological and evolutionary significance. Our long-term study of Lake Erie Watersnakes, Nerodia sipedon insularum, provides data sufficient for a detailed analysis of population and individual growth. We describe population mean growth separately for males and females based on size of known age individuals (847 captures of 769 males, 748 captures of 684 females) and annual growth increments of individuals of unknown age (1,152 males, 730 females). We characterize individual variation in asymptotic size based on repeated measurements of 69 males and 71 females that were each captured in five to nine different years. The most striking result of our analyses is that asymptotic size varies dramatically among individuals, ranging from 631–820 mm snout-vent length in males and from 835–1125 mm in females. Because female fecundity increases with increasing body size, we explore the impact of individual variation in asymptotic size on lifetime reproductive success using a range of realistic estimates of annual survival. When all females commence reproduction at the same age, lifetime reproductive success is greatest for females with greater asymptotic size regardless of annual survival. But when reproduction is delayed in females with greater asymptotic size, lifetime reproductive success is greatest for females with lower asymptotic size when annual survival is low. Possible causes of individual variation in asymptotic size, including individual- and cohort-specific variation in size at birth and early growth, warrant further investigation. PMID

  18. Dispersion Measure Variation of Repeating Fast Radio Burst Sources

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yuan-Pei; Zhang, Bing, E-mail: yypspore@gmail.com, E-mail: zhang@physics.unlv.edu [Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China)

    2017-09-20

    The repeating fast radio burst (FRB) 121102 was recently localized in a dwarf galaxy at a cosmological distance. The dispersion measure (DM) derived for each burst from FRB 121102 so far has not shown significant evolution, even though an apparent increase was recently seen with newly detected VLA bursts. It is expected that more repeating FRB sources may be detected in the future. In this work, we investigate a list of possible astrophysical processes that might cause DM variation of a particular FRB source. The processes include (1) cosmological scale effects such as Hubble expansion and large-scale structure fluctuations; (2) FRB local effects such as gas density fluctuation, expansion of a supernova remnant (SNR), a pulsar wind nebula, and an H ii region; and (3) the propagation effect due to plasma lensing. We find that the DM variations contributed by the large-scale structure are extremely small, and any observable DM variation is likely caused by the plasma local to the FRB source. In addition to mechanisms that decrease DM over time, we suggest that an FRB source in an expanding SNR around a nearly neutral ambient medium during the deceleration (Sedov–Taylor and snowplow) phases or in a growing H ii region can increase DM. Some effects (e.g., an FRB source moving in an H ii region or plasma lensing) can produce either positive or negative DM variations. Future observations of DM variations of FRB 121102 and other repeating FRB sources can provide important clues regarding the physical origin of these sources.

  19. Addressing unwarranted clinical variation: A rapid review of current evidence.

    Science.gov (United States)

    Harrison, Reema; Manias, Elizabeth; Mears, Stephen; Heslop, David; Hinchcliff, Reece; Hay, Liz

    2018-05-15

    Unwarranted clinical variation (UCV) can be described as variation that can only be explained by differences in health system performance. There is a lack of clarity regarding how to define and identify UCV and, once identified, to determine whether it is sufficiently problematic to warrant action. As such, the implementation of systemic approaches to reducing UCV is challenging. A review of approaches to understand, identify, and address UCV was undertaken to determine how conceptual and theoretical frameworks currently attempt to define UCV, the approaches used to identify UCV, and the evidence of their effectiveness. Rapid evidence assessment (REA) methodology was used. A range of text words, synonyms, and subject headings were developed for the major concepts of unwarranted clinical variation, standards (and deviation from these standards), and health care environment. Two electronic databases (Medline and Pubmed) were searched from January 2006 to April 2017, in addition to hand searching of relevant journals, reference lists, and grey literature. Results were merged using reference-management software (Endnote) and duplicates removed. Inclusion criteria were independently applied to potentially relevant articles by 3 reviewers. Findings were presented in a narrative synthesis to highlight key concepts addressed in the published literature. A total of 48 relevant publications were included in the review; 21 articles were identified as eligible from the database search, 4 from hand searching published work and 23 from the grey literature. The search process highlighted the voluminous literature reporting clinical variation internationally; yet, there is a dearth of evidence regarding systematic approaches to identifying or addressing UCV. Wennberg's classification framework is commonly cited in relation to classifying variation, but no single approach is agreed upon to systematically explore and address UCV. The instances of UCV that warrant investigation and

  20. Dispersion Measure Variation of Repeating Fast Radio Burst Sources

    International Nuclear Information System (INIS)

    Yang, Yuan-Pei; Zhang, Bing

    2017-01-01

    The repeating fast radio burst (FRB) 121102 was recently localized in a dwarf galaxy at a cosmological distance. The dispersion measure (DM) derived for each burst from FRB 121102 so far has not shown significant evolution, even though an apparent increase was recently seen with newly detected VLA bursts. It is expected that more repeating FRB sources may be detected in the future. In this work, we investigate a list of possible astrophysical processes that might cause DM variation of a particular FRB source. The processes include (1) cosmological scale effects such as Hubble expansion and large-scale structure fluctuations; (2) FRB local effects such as gas density fluctuation, expansion of a supernova remnant (SNR), a pulsar wind nebula, and an H ii region; and (3) the propagation effect due to plasma lensing. We find that the DM variations contributed by the large-scale structure are extremely small, and any observable DM variation is likely caused by the plasma local to the FRB source. In addition to mechanisms that decrease DM over time, we suggest that an FRB source in an expanding SNR around a nearly neutral ambient medium during the deceleration (Sedov–Taylor and snowplow) phases or in a growing H ii region can increase DM. Some effects (e.g., an FRB source moving in an H ii region or plasma lensing) can produce either positive or negative DM variations. Future observations of DM variations of FRB 121102 and other repeating FRB sources can provide important clues regarding the physical origin of these sources.