Oxidative conditions prevail in severe IUGR with vascular disease and Doppler anomalies.
Maisonneuve, Emeline; Delvin, Edgard; Edgard, Annie; Morin, Lucie; Dubé, Johanne; Boucoiran, Isabelle; Moutquin, Jean-Marie; Fouron, Jean-Claude; Klam, Stephanie; Levy, Emile; Leduc, Line
2015-08-01
Intrauterine growth restriction (IUGR) and prenatal exposure to oxidative stress are thought to lead to increased risks of cardiovascular disease later in life. The objective of the present study was to document whether cord blood oxidative stress biomarkers vary with the severity of IUGR and of vascular disease in the twin pregnancy model in which both fetuses share the same maternal environment. This prospective cohort study involved dichorionic twin pairs, with one co-twin with IUGR. Oxidative stress biomarkers were measured in venous cord blood samples from each neonate of 32 twin pairs, and compared, according to severity of IUGR (IUGR <5th percentile), Doppler anomalies of the umbilical artery and early onset IUGR (in the second trimester) of the growth restricted twin. Oxidized Low-Density Lipoproteins (oxLDL) and Malondialdehyde (MDA) concentrations were increased proportionally in cases of severe IUGR. OxLDL concentrations were also increased in cases of IUGR with Doppler anomaly. Our data indicate that severe IUGR, is related to a derangement in redox balance, illustrated by increased venous cord blood oxidative stress biomarkers concentrations. Severe IUGR and IUGR with abnormal Doppler can be translated into conditions with intense oxidative stress.
[Prenatal management of isolated IUGR].
Senat, M-V; Tsatsaris, V
2013-12-01
To evaluate the performance of different antenatal tools for the monitoring of fetuses with isolated intrauterine growth restriction (IUGR). To define the prenatal management of IUGR and indications for delivery before and after 32 weeks of gestation. PubMed, Embase and the Cochrane databases were searched using the keywords "IUGR", "fetal growth restriction", "cardiotocography", "amniotic fluid", "ultrasound assessment", "biophysical profile", "Doppler ultrasonography", "randomized trial", "meta-analysis". These terms were also combined together. Fetal monitoring of isolated IUGR should be based on the combined use of fetal heart rate (FHR) and ultrasound Doppler. The use of computerized FHR, with short-term variability (STV) measurement allows longitudinal monitoring and provides objective values upon which to decide very premature delivery (LE3). The use of umbilical Doppler is associated with a decrease in perinatal morbidity, especially in IUGR (LE1). It should be the first-line mean for the monitoring of SGA and IUGR fetuses (LE1). The additional use of cerebral Doppler is associated with a better predictive value for a poor perinatal outcome than the umbilical Doppler alone (LE3). Therefore, cerebral Doppler should be used in fetuses with IUGR, whether the umbilical Doppler is normal or not. As morbidity and mortality is increased in IUGR with pathological ductus venosus, the use of this Doppler should be considered in the monitoring of IUGR at before 32 weeks (professional consensus). Routine hospitalization is not mandatory for the monitoring of fetuses with IUGR/SGA. However, tertiary referral is advisable in cases of severe IUGR at between 26 to 32 weeks (professional consensus). The decision for delivery cannot be standardized and should be based on the combined analysis of gestational age, fetal heart rate analysis and Doppler study (professional consensus). Monitoring of fetuses with IUGR and decision for delivery should be based on the combined
Perrotin, F; Simon, E G; Potin, J; Laffon, M
2013-12-01
The purpose of this paper is to review available data regarding the management of delivery in intra uterine growth retarded fetuses and try to get recommendations for clinical obstetrical practice. Bibliographic research performed by consulting PubMed database and recommendations from scientific societies with the following words: small for gestational age, intra-uterine growth restriction, fetal growth restriction, very low birth weight infants, as well as mode of delivery, induction of labor, cesarean section and operative delivery. The diagnosis of severe IUGR justifies the orientation of the patient to a referral centre with all necessary resources for very low birth weight or premature infants Administration of corticosteroids for fetal maturation (before 34 WG) and a possible neuroprotective treatment by with magnesium sulphate (before 32-33 WG) should be discussed. Although elective caesarean section is common, there is no current evidence supporting the use of systematic cesarean section, especially when the woman is in labor. Induction of labor, even with unfavorable cervix is possible under continuous FHR monitoring, in favorable obstetric situations and in the absence of severe fetal hemodynamic disturbances. Instrumental delivery and routine episiotomy are not recommended. For caesarean section under spinal anesthesia, an adequate anesthetic management must ensure the maintenance of basal blood pressure. Compared with appropriate for gestational age fetus, IUGR fetus is at increased risk of metabolic acidosis or perinatal asphyxia during delivery. Copyright © 2013 Elsevier Masson SAS. All rights reserved.
IUGR Management: New Perspectives
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N. Giuliano
2014-01-01
Full Text Available Aim of the Study. Analyzing velocimetric (umbilical artery, UA; ductus venosus, DV; middle cerebral artery, MCA and computerized cardiotocographic (cCTG (fetal heart rate, FHR; short term variability, STV; approximate entropy, ApEn parameters in intrauterine growth restriction, IUGR, in order to detect early signs of fetal compromise. Population Study. 375 pregnant women assisted from the 28th week of amenorrhea to delivery and monitored through cCTG and Doppler ultrasound investigation. The patients were divided into three groups according to the age of gestation at the time of delivery, before the 34th week, from 34th to 37th week, and after the 37th week. Data were analyzed in relation to the days before delivery and according to the physiology or pathology of velocimetry. Statistical analysis was performed through the t-test, chi-square test, and Pearson correlation test (P<0.05. Our results evidenced an earlier alteration of UA, DV, and MCA. The analysis between cCTG and velocimetric parameters (the last distinguished into physiological and pathological values suggests a possible relation between cCTG alterations and Doppler ones. The present study emphasizes the need for an antenatal testing in IUGR fetuses using multiple surveillance modalities to enhance prediction of neonatal outcome.
[Managing and identifying the causes of IUGR].
Salomon, L J; Malan, V
2013-12-01
The management and identification of the causes for a small for gestational age (SGA) and/or an intrauterine growth restriction (IUGR) fetus is a common but complex problem in Obstetrics. The Medline, Embase and the Cochrane Library databases were examined over the last 15 years, with no language restrictions, using a combination of the words PAG (SGA), IUGR (IUGR), fetal weight (Fetal weight), sonography (ultrasound), management, cause (etiology), examinations (examinations). Some references not selected by this strategy, but associated with these publications or suggested by members of the working group were also added. The relevant articles were used to establish the text of recommendation following discussion between experts of the working group. Once the diagnosis of SGA is raised (whether on clinical, echocardiographic or Doppler), a management strategy to look for potential causes must be proposed and discussed with parents (Expert reviews). The extent of additional explorations varies depending on the exact presentation of the case (term at diagnosis, severity of anomalies). Additional explorations only make sense if they are likely to change the management of the current pregnancy and particularly to reduce perinatal morbidity and mortality. Explorations have two main objectives: (i) assess fetal vitality and possibilities for continuing the pregnancy in terms of safety for the mother and the foetus; (ii) establish the origin of SGA. The latter is detailed in this chapter recommendation. The earlier and the more severe the biometric anomalies, the more comprehensive the investigations. Maternal symptoms or fetal Doppler anomalies also require urgent management. Explorations to establish the origin of SGA and/or IUGR must follow a rigorous and systematic approach. In all cases, the practitioner will provide clear information to parents and collect information including detailed clinical and ultrasound examinations. Additional tests and in particular fetal
The impact of IUGR on pancreatic islet development and β-cell function.
Boehmer, Brit H; Limesand, Sean W; Rozance, Paul J
2017-11-01
Placental insufficiency is a primary cause of intrauterine growth restriction (IUGR). IUGR increases the risk of developing type 2 diabetes mellitus (T2DM) throughout life, which indicates that insults from placental insufficiency impair β-cell development during the perinatal period because β-cells have a central role in the regulation of glucose tolerance. The severely IUGR fetal pancreas is characterized by smaller islets, less β-cells, and lower insulin secretion. Because of the important associations among impaired islet growth, β-cell dysfunction, impaired fetal growth, and the propensity for T2DM, significant progress has been made in understanding the pathophysiology of IUGR and programing events in the fetal endocrine pancreas. Animal models of IUGR replicate many of the observations in severe cases of human IUGR and allow us to refine our understanding of the pathophysiology of developmental and functional defects in islet from IUGR fetuses. Almost all models demonstrate a phenotype of progressive loss of β-cell mass and impaired β-cell function. This review will first provide evidence of impaired human islet development and β-cell function associated with IUGR and the impact on glucose homeostasis including the development of glucose intolerance and diabetes in adulthood. We then discuss evidence for the mechanisms regulating β-cell mass and insulin secretion in the IUGR fetus, including the role of hypoxia, catecholamines, nutrients, growth factors, and pancreatic vascularity. We focus on recent evidence from experimental interventions in established models of IUGR to understand better the pathophysiological mechanisms linking placental insufficiency with impaired islet development and β-cell function. © 2017 Society for Endocrinology.
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Magdalena Sanz-Cortés
Full Text Available OBJECTIVES: To characterize via NMR spectroscopy the full spectrum of metabolic changes in umbilical vein blood plasma of newborns diagnosed with different clinical forms of intrauterine growth restriction (IUGR. METHODS: 23 early IUGR cases and matched 23 adequate-for-gestational-age (AGA controls and 56 late IUGR cases with 56 matched AGAs were included in this study. Early IUGR was defined as a birth weight 35 weeks. This group was subdivided in 18 vasodilated (VD and 38 non-VD late IUGR fetuses. All AGA patients had a birth weight >10(th centile. (1H nuclear magnetic resonance (NMR metabolomics of the blood samples collected from the umbilical vein at delivery was obtained. Multivariate statistical analysis identified several metabolites that allowed the discrimination between the different IUGR subgroups, and their comparative levels were quantified from the NMR data. RESULTS: The NMR-based analysis showed increased unsaturated lipids and VLDL levels in both early and late IUGR samples, decreased glucose and increased acetone levels in early IUGR. Non-significant trends for decreased glucose and increased acetone levels were present in late IUGR, which followed a severity gradient when the VD and non-VD subgroups were considered. Regarding amino acids and derivatives, early IUGR showed significantly increased glutamine and creatine levels, whereas the amounts of phenylalanine and tyrosine were decreased in early and late-VD IUGR samples. Valine and leucine were decreased in late IUGR samples. Choline levels were decreased in all clinical subforms of IUGR. CONCLUSIONS: IUGR is not associated with a unique metabolic profile, but important changes are present in different clinical subsets used in research and clinical practice. These results may help in characterizing comprehensively specific alterations underlying different IUGR subsets.
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Janna L. Morrison
2012-01-01
Full Text Available Glucocorticoids are administered to pregnant women at risk of preterm labour to promote fetal lung surfactant maturation. Intrauterine growth restriction (IUGR is associated with an increased risk of preterm labour. Hence, IUGR babies may be exposed to antenatal glucocorticoids. The ability of the placenta or blood brain barrier to remove glucocorticoids from the fetal compartment or the brain is compromised in the IUGR fetus, which may have implications for lung, brain, and heart development. There is conflicting evidence on the effect of exogenous glucocorticoids on surfactant protein expression in different animal models of IUGR. Furthermore, the IUGR fetus undergoes significant cardiovascular adaptations, including altered blood pressure regulation, which is in conflict with glucocorticoid-induced alterations in blood pressure and flow. Hence, antenatal glucocorticoid therapy in the IUGR fetus may compromise regulation of cardiovascular development. The role of cortisol in cardiomyocyte development is not clear with conflicting evidence in different species and models of IUGR. Further studies are required to study the effects of antenatal glucocorticoids on lung, brain, and heart development in the IUGR fetus. Of specific interest are the aetiology of IUGR and the resultant degree, duration, and severity of hypoxemia.
Morrison, Janna L; Botting, Kimberley J; Soo, Poh Seng; McGillick, Erin V; Hiscock, Jennifer; Zhang, Song; McMillen, I Caroline; Orgeig, Sandra
2012-01-01
Glucocorticoids are administered to pregnant women at risk of preterm labour to promote fetal lung surfactant maturation. Intrauterine growth restriction (IUGR) is associated with an increased risk of preterm labour. Hence, IUGR babies may be exposed to antenatal glucocorticoids. The ability of the placenta or blood brain barrier to remove glucocorticoids from the fetal compartment or the brain is compromised in the IUGR fetus, which may have implications for lung, brain, and heart development. There is conflicting evidence on the effect of exogenous glucocorticoids on surfactant protein expression in different animal models of IUGR. Furthermore, the IUGR fetus undergoes significant cardiovascular adaptations, including altered blood pressure regulation, which is in conflict with glucocorticoid-induced alterations in blood pressure and flow. Hence, antenatal glucocorticoid therapy in the IUGR fetus may compromise regulation of cardiovascular development. The role of cortisol in cardiomyocyte development is not clear with conflicting evidence in different species and models of IUGR. Further studies are required to study the effects of antenatal glucocorticoids on lung, brain, and heart development in the IUGR fetus. Of specific interest are the aetiology of IUGR and the resultant degree, duration, and severity of hypoxemia.
Wölter, M; Röwer, C; Koy, C; Rath, W; Pecks, U; Glocker, M O
2016-10-21
Intrauterine growth restriction (IUGR) is an important cause of perinatal morbidity and mortality and contributes substantially to medically indicated preterm birth; preventing fetal death. Molecular profiling of the mothers' peripheral blood was desired to monitor the health conditions of the fetuses. To develop such a minimally invasive assay, we applied a protein affinity fractionation method to peripheral blood serum samples from pregnant women belonging to either the IUGR or to the control group. Proof-of-principle was shown by relative quantitation analysis of mixtures of intact proteoforms using MALDI-ToF mass spectrometry. The two best differentiating proteins and proteoforms, respectively, were apolipoprotein C-II and apolipoprotein C-III 0 . Together with three robustly expressed protein proteoforms proapolipoprotein C-II, apolipoprotein C-III 1 , and apolipoprotein C-III 2 , which served as landmarks for relative quantitation analysis, they constituted the maternal IUGR proteome signature. Separation confidence of our IUGR proteoform signature reached a sensitivity of 0.73 and a specificity of 0.87 with an area under curve of 0.86 in receiver operator characteristics. Identification of IUGR newborns in the case room is required as children are severely diseased and need specialized care during infancy. Yet, at time of birth there is no readily applicable clinical test available. Hence, a molecular profiling assay is highly desired. It needs to be mentioned that current clinical definitions and recommendations for IUGR are unfortunately misleading and are not universally applicable. The most commonly adopted definition is an abdominal circumference (AC) or estimated fetal weight measurement protein composition (IUGR signature) which can be determined just ahead of delivery and at date of delivery, respectively using a minimal invasive blood sampling approach. With this manuscript we describe the use of a mass spectrometric profiling method of 30
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Stefan Hutter
2016-04-01
Full Text Available Galectins (gal are members of the mammalian β-galactoside-binding proteins and recognize Galβ1-4GlcNAc and Galβ1-4GalNac (Thomsen-Friedenreich antigen (TF sequences of several cell surface oligosaccharides. In this study, gal-1, -2, -3 and -13 were investigated systematically in the trophoblast and decidua compartment of intrauterine growth restriction (IUGR placentas and normal third trimester control placentas and stratified by fetal gender and gestational age. Within this study, 29 third trimester placentas after delivery were analyzed. Fetal gender was equally divided within both groups, and immunohistochemical staining was analyzed according to fetal gender and gestational age. Double immune-fluorescence with trophoblast-specific markers was used to identify galectin-expressing cells at the feto-maternal interface in the decidua. Gal-3 was significantly downregulated only in the extravillous trophoblast of IUGR placentas. In contrast, expressions of gal-2 and gal-13 were downregulated in both villous and extravillous trophoblast cells of IUGR placentas. In addition, gal-2 and gal-13 showed a highly correlated expression scheme in the placenta. There are significant gender-specific expression patterns for single prototype galectins with downregulation of gal-2 and gal-13 of male gender placentas in cases of IUGR. Gal-3 as the chimera type galectin shows only little gender-specific differences in expression, which disappear in IUGR cases.
International Nuclear Information System (INIS)
Moreno, Nicolás; Malagón, Andrés; Buchner, Richard; Vargas, Edgar F.
2014-01-01
Highlights: • Apparent molal volumes of five isomers of Bu 4 NBr in water have been measured. • The structural effect of branched and linear chains is discussed. • The structural contributions to the ionic volume were calculated. -- Abstract: Apparent molal volumes of a series of differently substituted quaternary ammonium bromides, namely tetra-iso-butyl-, tetra-sec-butyl-, tetra-n-butyl-, di-n-butyl-di-sec-butyl- and di-n-butyl-di-iso-butylammonium bromide have been determined as a function of molal concentration at (298.15, 303.15 and 308.15) K. Partial molar volumes at infinite dilution and ionic molar volumes of these quaternary ammonium cations were determined. Structural volume contributions to the ionic molar volume were also calculated. The symmetric and asymmetric quaternary ammonium cations are “structure making” ions. The contribution of the branched butyl chains predominates over the linear butyl chains in the asymmetric cations
Buffat, C; Mondon, F; Rigourd, V; Boubred, F; Bessières, B; Fayol, L; Feuerstein, J-M; Gamerre, M; Jammes, H; Rebourcet, R; Miralles, F; Courbières, B; Basire, A; Dignat-Georges, F; Carbonne, B; Simeoni, U; Vaiman, D
2007-11-01
Intra-uterine growth restriction (IUGR) is a frequent disease, affecting up to 10% of human pregnancies and responsible for increased perinatal morbidity and mortality. Moreover, low birth weight is an important cause of the metabolic syndrome in the adult. Protein depletion during the gestation of rat females has been widely used as a model for human IUGR. By transcriptome analysis of control and protein-deprived rat placentas, we were able to identify 2543 transcripts modified more than 2.5 fold (1347 induced and 1196 repressed). Automatic functional classification enabled us to identify clusters of induced genes affecting chromosome structure, transcription, intracellular transport, protein modifications and apoptosis. In particular, we suggest the existence of a complex balance regulating apoptosis. Among repressed genes, we noted several groups of genes involved in immunity, signalling and degradation of noxious chemicals. These observations suggest that IUGR placentas have a decreased resistance to external aggression. The promoters of the most induced and most repressed genes were contrasted for their composition in putative transcription factor binding sites. There was an over-representation of Zn finger (ZNF) proteins and Pdx1 (pancreatic and duodenal homeobox protein 1) putative binding sites. Consistently, Pdx1 and a high proportion of ZNF genes were induced at the transcriptional level. A similar analysis of ZNF promoters showed an increased presence of putative binding sites for the Tata box binding protein (Tbp). Consistently again, we showed that the Tbp and TBP-associated factors (Tafs) were up-regulated in IUGR placentas. Also, samples of human IUGR and control placentas showed that human orthologous ZNFs and PDX1 were transcriptionally induced, especially in non-vascular IUGR. Immunohistochemistry revealed increased expression of PDX1 in IUGR human placentas. In conclusion, our approach permitted the proposition of hypotheses on a hierarchy of
ACUTE HYPOGLYCEMIA RESULTS IN REDUCED CORTICAL NEURONAL INJURY IN THE DEVELOPING IUGR RAT
Maliszewski-Hall, Anne M.; Stein, Ariel B.; Alexander, Michelle; Ennis, Kathleen; Rao, Raghavendra
2015-01-01
Background Hypoglycemia (HG) is common in IUGR neonates. In normally grown (NG) neonatal rats, acute HG causes neuronal injury in the brain, cerebral cortex more vulnerable than the hippocampus (HPC). We hypothesized that the IUGR brain is less vulnerable to hypoglycemia-induced injury while preserving the regional variation in vulnerability. Methods We induced IUGR via bilateral uterine artery ligation on gestational day 19 (term 22d) rats. On postnatal day 14, insulin-induced HG of equivale...
Soto, Susan M; Blake, Amy C; Wesolowski, Stephanie R; Rozance, Paul J; Barthel, Kristen B; Gao, Bifeng; Hetrick, Byron; McCurdy, Carrie E; Garza, Natalia G; Hay, William W; Leinwand, Leslie A; Friedman, Jacob E; Brown, Laura D
2017-03-01
Adults who were affected by intrauterine growth restriction (IUGR) suffer from reductions in muscle mass and insulin resistance, suggesting muscle growth may be restricted by molecular events that occur during fetal development. To explore the basis of restricted fetal muscle growth, we used a sheep model of progressive placental insufficiency-induced IUGR to assess myoblast proliferation within intact skeletal muscle in vivo and isolated myoblasts stimulated with insulin in vitro Gastrocnemius and soleus muscle weights were reduced by 25% in IUGR fetuses compared to those in controls (CON). The ratio of PAX7+ nuclei (a marker of myoblasts) to total nuclei was maintained in IUGR muscle compared to CON, but the fraction of PAX7+ myoblasts that also expressed Ki-67 (a marker of cellular proliferation) was reduced by 23%. Despite reduced proliferation in vivo, fetal myoblasts isolated from IUGR biceps femoris and cultured in enriched media in vitro responded robustly to insulin in a dose- and time-dependent manner to increase proliferation. Similarly, insulin stimulation of IUGR myoblasts upregulated key cell cycle genes and DNA replication. There were no differences in the expression of myogenic regulatory transcription factors that drive commitment to muscle differentiation between CON and IUGR groups. These results demonstrate that the molecular machinery necessary for transcriptional control of proliferation remains intact in IUGR fetal myoblasts, indicating that in vivo factors such as reduced insulin and IGF1, hypoxia and/or elevated counter-regulatory hormones may be inhibiting muscle growth in IUGR fetuses. © 2017 Society for Endocrinology.
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Xu Xue-Feng
2013-02-01
Full Text Available Abstract Background Accumulating evidence reveals that intrauterine growth retardation (IUGR can cause varying degrees of pulmonary arterial hypertension (PAH later in life. Moreover, epigenetics plays an important role in the fetal origin of adult disease. The goal of this study was to investigate the role of epigenetics in the development of PAH following IUGR. Methods The IUGR rats were established by maternal undernutrition during pregnancy. Pulmonary vascular endothelial cells (PVEC were isolated from the rat lungs by magnetic-activated cell sorting (MACS. We investigated epigenetic regulation of the endothelin-1 (ET-1 gene in PVEC of 1-day and 6-week IUGR rats, and response of IUGR rats to hypoxia. Results The maternal nutrient restriction increased the histone acetylation and hypoxia inducible factor-1α (HIF-1α binding levels in the ET-1 gene promoter of PVEC in IUGR newborn rats, and continued up to 6 weeks after birth. These epigenetic changes could result in an IUGR rat being highly sensitive to hypoxia later in life, causing more significant PAH or pulmonary vascular remodeling. Conclusions These findings suggest that epigenetics is closely associated with the development of hypoxic PAH following IUGR, further providing a new insight for improved prevention and treatment of IUGR-related PAH.
Predictable progressive Doppler deterioration in IUGR: does it really exist?
LENUS (Irish Health Repository)
Unterscheider, Julia
2013-12-01
An objective of the Prospective Observational Trial to Optimize Pediatric Health in IUGR (PORTO) study was to evaluate multivessel Doppler changes in a large cohort of intrauterine growth restriction (IUGR) fetuses to establish whether a predictable progressive sequence of Doppler deterioration exists and to correlate these Doppler findings with respective perinatal outcomes.
ROLE OF PARENTERAL AMINO ACIDS SUPPLEMENATION IN OLIGOHYDRAMNIOS & IUGR COMPLICATED PREGNANCIES
Anuradha; Malini; Sumit
2015-01-01
OBJECTIVES: To see whether parenteral nutritional supplementation of women with oligohydramnios/IUGR can improve the amount of liquor and to evaluate the role of pareneral therapy in improving maternal and perinatal outcome and to correlate between the occurrence of oligohydramnios and IUGR among women of different age, parity, education and socioe...
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Heidi N. Bagley
2013-01-01
Full Text Available Intrauterine growth restriction (IUGR predisposes to obesity and adipose dysfunction. We previously demonstrated IUGR-induced increased visceral adipose deposition and dysregulated expression of peroxisome proliferator activated receptor-γ2 (PPARγ2 in male adolescent rats, prior to the onset of obesity. In other studies, activation of PPARγ increases subcutaneous adiponectin expression and normalizes visceral adipose deposition. We hypothesized that maternal supplementation with docosahexaenoic acid (DHA, a PPARγ agonist, would normalize IUGR adipose deposition in association with increased PPARγ, adiponectin, and adiponectin receptor expression in subcutaneous adipose. To test these hypotheses, we used a well-characterized model of uteroplacental-insufficiency-(UPI- induced IUGR in the rat with maternal DHA supplementation. Our primary findings were that maternal DHA supplementation during rat pregnancy and lactation (1 normalizes IUGR-induced changes in adipose deposition and visceral PPARγ expression in male rats and (2 increases serum adiponectin, as well as adipose expression of adiponectin and adiponectin receptors in former IUGR rats. Our novel findings suggest that maternal DHA supplementation may normalize adipose dysfunction and promote adiponectin-induced improvements in metabolic function in IUGR.
Bagley, Heidi N; Wang, Yan; Campbell, Michael S; Yu, Xing; Lane, Robert H; Joss-Moore, Lisa A
2013-01-01
Intrauterine growth restriction (IUGR) predisposes to obesity and adipose dysfunction. We previously demonstrated IUGR-induced increased visceral adipose deposition and dysregulated expression of peroxisome proliferator activated receptor- γ 2 (PPAR γ 2) in male adolescent rats, prior to the onset of obesity. In other studies, activation of PPAR γ increases subcutaneous adiponectin expression and normalizes visceral adipose deposition. We hypothesized that maternal supplementation with docosahexaenoic acid (DHA), a PPAR γ agonist, would normalize IUGR adipose deposition in association with increased PPAR γ , adiponectin, and adiponectin receptor expression in subcutaneous adipose. To test these hypotheses, we used a well-characterized model of uteroplacental-insufficiency-(UPI-) induced IUGR in the rat with maternal DHA supplementation. Our primary findings were that maternal DHA supplementation during rat pregnancy and lactation (1) normalizes IUGR-induced changes in adipose deposition and visceral PPAR γ expression in male rats and (2) increases serum adiponectin, as well as adipose expression of adiponectin and adiponectin receptors in former IUGR rats. Our novel findings suggest that maternal DHA supplementation may normalize adipose dysfunction and promote adiponectin-induced improvements in metabolic function in IUGR.
Symmetric cryptographic protocols
Ramkumar, Mahalingam
2014-01-01
This book focuses on protocols and constructions that make good use of symmetric pseudo random functions (PRF) like block ciphers and hash functions - the building blocks for symmetric cryptography. Readers will benefit from detailed discussion of several strategies for utilizing symmetric PRFs. Coverage includes various key distribution strategies for unicast, broadcast and multicast security, and strategies for constructing efficient digests of dynamic databases using binary hash trees. • Provides detailed coverage of symmetric key protocols • Describes various applications of symmetric building blocks • Includes strategies for constructing compact and efficient digests of dynamic databases
International Nuclear Information System (INIS)
Chen Wen; Zhong Jianhui; Shen Junnan
2005-01-01
Objective: To explore the interrelationship between presence of serum ACA and development of IUGR. Methods: Serum ACA contents were examined with ELISA in 5330 apparently normal pregnant women. The placentae in 16 pregnancies with IUGR and positive ACA were examined with immunofluorescence microscopy. Results: Among the 5330 pregnant women there were 144 with positive ACA (2.70%), in whom there were 22 IUGR cases (22/144, 15.28% ). The rate of IUGR in the remaining ACA negative women was only 1.77% (92/5186), the difference being very significant (P<0.01 ). ACA IgG was positive in 5 of the IUGR neonates, All the placental tissues examined with immunofluorescence microscopy showed positive immunoglobulin fluorescence antibody and complement discoloration. Conclusion: Positive ACA is one of the causative factors of development of IUGR and determination of ACA in pregnant women was helpful for early detection of IUGR. (authors)
International Nuclear Information System (INIS)
Ramond, P.
1993-01-01
The Wolfenstein parametrization is extended to the quark masses in the deep ultraviolet, and an algorithm to derive symmetric textures which are compatible with existing data is developed. It is found that there are only five such textures
Puga, B; Ferrández Longás, A; García Romero, R; Mayayo, E; Labarta, J I
2004-03-01
The possible impact of IUGR on the intellectual outcome of children born with IUGR gives special relevance to this condition. In order to determine the psychomotor and intellectual development of such children, we analyzed the evolution of 60 children through appropriate tests, along the years, and the possible influence of two factors, the socio-economic status of the family, and whether or not there was catch-up growth. Our results show a negative impact of IUGR on the intellectual outcome of these children, independent of catch-up growth, although those with catch-up growth showed better evolution. The socio-economic status plays a limited role only at older age. Those children followed longitudinally for 1 year did not show any amelioration of their IQ.
Candel Pau, Júlia; Castillo Salinas, Félix; Perapoch López, Josep; Carrascosa Lezcano, Antonio; Sánchez García, Olga; Llurba Olivé, Elisa
2016-10-01
Intrauterine growth restriction (IUGR) and prematurity have been associated with increased perinatal morbidity and mortality and also with cardiovascular foetal programming. However, there are few studies on the impact of placenta-related IUGR on perinatal outcomes and cardiovascular biomarkers in pre-term infants. To determine differences in neonatal morbidity, mortality and cord blood biomarkers of cardiovascular dysfunction between pre-term placenta-related IUGR and non-IUGR new-borns, and to analyse their relationship with the severity of IUGR according to foetal Doppler evaluation. Prospective cohort study: pre-term infants with placenta-related IUGR and matched pre-term infants without IUGR. A Doppler scan was performed, and placenta-IUGR was classified according to severity. Comparative analysis of perinatal outcomes, neonatal morbidity and mortality, and cord blood levels of biomarkers of cardiovascular dysfunction was performed. IUGR new-borns present lower weight, length, head circumference, and Apgar score at birth, as well as increased neonatal and cardiovascular dysfunction biomarker levels, compared with pre-term new-borns without IUGR. These differences increase with the severity of IUGR determined by prenatal umbilical artery Doppler scan. Placenta-related-IUGR pre-term infants, irrespective of gestational age, present increased neonatal morbidity and mortality that is significantly proportional to the severity of IUGR. Placental impairment and severity also determine levels of cardiovascular dysfunction biomarkers at birth. Copyright © 2015 Asociación Española de Pediatría. Publicado por Elsevier España, S.L.U. All rights reserved.
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Siddiqui Saad
2011-04-01
Full Text Available Abstract Background There is a strong association between stillbirth and fetal growth restriction. Early detection and management of IUGR can lead to reduce related morbidity and mortality. In this paper we have reviewed effectiveness of fetal movement monitoring and Doppler velocimetry for the detection and surveillance of high risk pregnancies and the effect of this on prevention of stillbirths. We have also reviewed effect of maternal body mass index (BMI screening, symphysial-fundal height measurement and targeted ultrasound in detection and triage of IUGR in the community. Methods We systematically reviewed all published literature to identify studies related to our interventions. We searched PubMed, Cochrane Library, and all World Health Organization Regional Databases and included publications in any language. Quality of available evidence was assessed using GRADE criteria. Recommendations were made for the Lives Saved Tool (LiST based on rules developed by the Child Health Epidemiology Group. Given the paucity of evidence related to the effect of detection and management of IUGR on stillbirths, we undertook Delphi based evaluation from experts in the field. Results There was insufficient evidence to recommend against or in favor of routine use of fetal movement monitoring for fetal well being. (1 Detection and triage of IUGR with the help of (1a maternal BMI screening, (1b symphysial-fundal height measurement and (1c targeted ultrasound can be an effective method of reducing IUGR related perinatal morbidity and mortality. Pooled results from sixteen studies shows that Doppler velocimetry of umbilical and fetal arteries in ‘high risk’ pregnancies, coupled with the appropriate intervention, can reduce perinatal mortality by 29 % [RR 0.71, 95 % CI 0.52-0.98]. Pooled results for impact on stillbirth showed a reduction of 35 % [RR 0.65, 95 % CI 0.41-1.04]; however, the results did not reach the conventional limits of statistical
Hepatic aminotransferases of normal and IUGR fetuses in cord blood at birth.
Kocylowski, Rafal; Dubiel, Mariusz; Gudmundsson, Saemundur; Fritzer, Elfriede; Kiserud, Torvid; von Kaisenberg, Constantin
2012-07-01
The accepted standard for assessing the wellbeing of the newborn is the Apgar score and blood gas analysis. However, the prediction of neonatal morbidity or mortality is limited. In small-for-gestation (SGA) fetuses at 18-38 weeks of gestation, pO(2) is normals. To test the hypothesis, that fetuses with intra uterine growth restriction (IUGR) have elevated AST (GOT) and ALT (GPT) aminotransferases as a result of hypoxic liver cell injury, and to establish references ranges. Prospective cohort study, serum of umbilical artery (n=156) and vein (n=180), 599 normal singletons at 37(+0)-42(+0)weeks, neonates with IUGR (n=41), analysis for pH, birthweight and maternal weight, spontaneous vs cesarean section, vein vs artery and for the sex. Aspartate aminotransferase (AST, GOT) and Alanine aminotransferase (ALT, GPT) were measured in normals and IUGR neonates. Neonates with IUGR (n=41) had AST values that were not different from the reference group, but had significantly lower ALT (-1.49, 95% CI -1.98 to -1.00 vs 0.14, 95% CI -0.42-0.13), (pblood were not elevated. Rather, a substantially reduced ALT suggests a down-regulated hepatic activity. Copyright © 2011 Elsevier Ltd. All rights reserved.
Growth pattern of preterm and IUGR babies in an urban slum of ...
African Journals Online (AJOL)
The present study was carried out to analyze the growth pattern of preterm and IUGR infants from birth up to nine months of age. A longitudinal study was conducted in an urban slum of Chetla, Kolkata, India. Study population comprised of 36 low birth weight babies, out of which 13 were preterms and rest 23 were IUGR ...
Perinatal asphyxia and oxidative stress: studies in preterm IUGR pregnancies and term acute asphyxia
Torrance, H.L.
2008-01-01
Pregnancies complicated by intrauterine growth restriction (IUGR), preeclampsia (PE) or HELLP syndrome often have to be terminated prematurely. As a consequence of the early gestational age (GA) at delivery, infants born from these pregnancies are at increased risk of developing respiratory
Gender-specific heart rate dynamics in severe intrauterine growth-restricted fetuses.
Gonçalves, Hernâni; Bernardes, João; Ayres-de-Campos, Diogo
2013-06-01
Management of intrauterine growth restriction (IUGR) remains a major issue in perinatology. The objective of this paper was the assessment of gender-specific fetal heart rate (FHR) dynamics as a diagnostic tool in severe IUGR. FHR was analyzed in the antepartum period in 15 severe IUGR fetuses and 18 controls, matched for gestational age, in relation to fetal gender. Linear and entropy methods, such as mean FHR (mFHR), low (LF), high (HF) and movement frequency (MF), approximate, sample and multiscale entropy. Sensitivities and specificities were estimated using Fisher linear discriminant analysis and the leave-one-out method. Overall, IUGR fetuses presented significantly lower mFHR and entropy compared with controls. However, gender-specific analysis showed that significantly lower mFHR was only evident in IUGR males and lower entropy in IUGR females. In addition, lower LF/(MF+HF) was patent in IUGR females compared with controls, but not in males. Rather high sensitivities and specificities were achieved in the detection of the FHR recordings related with IUGR male fetuses, when gender-specific analysis was performed at gestational ages less than 34 weeks. Severe IUGR fetuses present gender-specific linear and entropy FHR changes, compared with controls, characterized by a significantly lower entropy and sympathetic-vagal balance in females than in males. These findings need to be considered in order to achieve better diagnostic results. Copyright © 2013 Elsevier Ltd. All rights reserved.
Learning and memory disabilities in IUGR babies: Functional and molecular analysis in a rat model.
Camprubí Camprubí, Marta; Balada Caballé, Rafel; Ortega Cano, Juan A; Ortega de la Torre, Maria de Los Angeles; Duran Fernández-Feijoo, Cristina; Girabent-Farrés, Montserrat; Figueras-Aloy, Josep; Krauel, Xavier; Alcántara, Soledad
2017-03-01
1Intrauterine growth restriction (IUGR) is the failure of the fetus to achieve its inherent growth potential, and it has frequently been associated with neurodevelopmental problems in childhood. Neurological disorders are mostly associated with IUGR babies with an abnormally high cephalization index (CI) and a brain sparing effect. However, a similar correlation has never been demonstrated in an animal model. The aim of this study was to determine the correlations between CI, functional deficits in learning and memory and alterations in synaptic proteins in a rat model of IUGR. 2Utero-placental insufficiency was induced by meso-ovarian vessel cauterization (CMO) in pregnant rats at embryonic day 17 (E17). Learning performance in an aquatic learning test was evaluated 25 days after birth and during 10 days. Some synaptic proteins were analyzed (PSD95, Synaptophysin) by Western blot and immunohistochemistry. 3Placental insufficiency in CMO pups was associated with spatial memory deficits, which are correlated with a CI above the normal range. CMO pups presented altered levels of synaptic proteins PSD95 and synaptophysin in the hippocampus. 4The results of this study suggest that learning disabilities may be associated with altered development of excitatory neurotransmission and synaptic plasticity. Although interspecific differences in fetal response to placental insufficiency should be taken into account, the translation of these data to humans suggest that both IUGR babies and babies with a normal birth weight but with intrauterine Doppler alterations and abnormal CI should be closely followed to detect neurodevelopmental alterations during the postnatal period.
Relationship between cord blood IGF-I, IGFBP-3 levels and intrauterine growth retardation (IUGR)
International Nuclear Information System (INIS)
Yu Suqing; Chu Kaiqiu; Chen Shengjie
2008-01-01
Objective: To study the cord blood insulin-like growth factor-I (IGF-I) and its binding protein-3 (IGFBP-3) levels in neonates with intrauterine growth retardation (IUGR). Methods: Cord serum IGF-I (with RIA) and IGFBP-3 (with IRMA) levels were measured in 22 neonates with IUGR and 64 neonates with appropriate gestational age (AGA). Results: Cord blood IGF-I and IGFBP-3 levels in IUGR neonates were significantly lower than those in AGA neonates (P<0.001). Among the 86 neonates studied in this article, 44 were born pre-term and 42 were born full term. From the data, we could see that the cord blood IGF-I and IGFBP-3 levels in pre-term neonates were significantly lower than those in full-term neonates (P also <0.001). IGF-I and IGFBP-3 levels were mutually positively correlated (P<0.01). Conclusion: Cord blood IGF-I and IGFBP-3 levels were useful indicator of neonates growth. (authors)
Directory of Open Access Journals (Sweden)
M.D. Ruiz-González
2016-12-01
Full Text Available The data are related to the proteomic analysis of 43 newborns with intrauterine growth retardation (IUGR and 45 newborns with appropriate weight for gestational age (AGA carried out by separation via 2DE and analyzed by MS–TOF/TOF. All newborns were separated into three gestational age groups, "Very Preterm" 29–32 weeks, "Moderate Preterm" 33–36 weeks, and, "Term" ≥37weeks. From each newborn, blood was drawn three times from birth to 1 month life. High-abundant serum proteins were depleted, and the minority ones were separated by 2DE and analyzed for significant expression differences. The data reflect analytic and clinic variables analyzed globally and categorized by gestational age in relation to IUGR and the optimization of conditions for 2-DE separation. The data from this study are related to the research article entitled "Alterations of Protein Expression in Serum of Infants with Intrauterine Growth Restriction and Different Gestational Ages" (M.D. Ruis-González, M.D. Cañete, J.L. Gómez-Chaparro, N. Abril, R. Cañete, J. López-Barea, 2015 [1]. The present dataset of serum IUGR newborn proteome can be used as a reference for any study involving intrauterine growth restriction during the first month of life.
Escobar, R S; O'Donnell, K A; Colalillo, S; Pawlby, S; Steiner, M; Meaney, M J; Levitan, R D; Silveira, P P
2014-10-01
While most "fetal programming" area focused on metabolic disease, intrauterine growth restriction (IUGR) is also associated with a preference for less healthy food. Post-natal factors such as strained maternal-child interactions are equally related to obesogenic eating behaviors. We investigated if IUGR and the quality of the mother/child relationship affect emotional overeating in children. Participants were 196 children from a prospective birth cohort (the MAVAN project). As part of the protocol at 4 years of age, mothers completed the Children Eating Behavior Questionnaire (CEBQ) and mother-child interactions were scored during a structured task. A GLM adjusted for BMI examined the interaction between the "Atmosphere" score (ATM) task, sex and IUGR on the emotional over-eating domain of the CEBQ. There was a significant interaction of BWR vs. sex vs. ATM (P = .02), with no effects of IUGR, sex or ATM. The model was significant for girls with low ATM scores (B = -2.035, P = .014), but not for girls with high (P = 0.94) or boys with high (P = .27) or low (P = .19) ATM scores. Only in IUGR girls, 48 months emotional over-eating correlated with BMI at that age (r = 0.560, P = 0.013) and predicted BMI in the subsequent years (r = 0.654, P = 0.006 at 60 months and r = 0.750, P = 0.005 at 72 months). IUGR and exposure to a negative emotional atmosphere during maternal-child interactions predicted emotional overeating in girls but not in boys. The quality of mother-infant interaction may be an important target for interventions to prevent emotional overeating and overweight in early development, particularly in girls with a history of IUGR. Copyright © 2014 Elsevier Ltd. All rights reserved.
Olafsson, Gestur; Helgason, Sigurdur
1996-01-01
This book is intended to introduce researchers and graduate students to the concepts of causal symmetric spaces. To date, results of recent studies considered standard by specialists have not been widely published. This book seeks to bring this information to students and researchers in geometry and analysis on causal symmetric spaces.Includes the newest results in harmonic analysis including Spherical functions on ordered symmetric space and the holmorphic discrete series and Hardy spaces on compactly casual symmetric spacesDeals with the infinitesimal situation, coverings of symmetric spaces, classification of causal symmetric pairs and invariant cone fieldsPresents basic geometric properties of semi-simple symmetric spacesIncludes appendices on Lie algebras and Lie groups, Bounded symmetric domains (Cayley transforms), Antiholomorphic Involutions on Bounded Domains and Para-Hermitian Symmetric Spaces
Directory of Open Access Journals (Sweden)
Salvatore Tagliaferri
2015-01-01
Full Text Available Objective. This study used a new method called Acceleration (or Deceleration Phase-Rectified Slope, APRS (or DPRS to analyze computerized Cardiotocographic (cCTG traces in intrauterine growth restriction (IUGR, in order to calculate acceleration- and deceleration-related fluctuations of the fetal heart rate, and to enhance the prediction of neonatal outcome. Method. Cardiotocograms from a population of 59 healthy and 61 IUGR fetuses from the 30th gestation week matched for gestational age were included. APRS and DPRS analysis was compared to the standard linear and nonlinear cCTG parameters. Statistical analysis was performed through the t-test, ANOVA test, Pearson correlation test and receiver operator characteristic (ROC curves (p<0,05. Results. APRS and DPRS showed high performance to discriminate between Healthy and IUGR fetuses, according to gestational week. A linear correlation with the fetal pH at birth was found in IUGR. The area under the ROC curve was 0.865 for APRS and 0.900 for DPRS before the 34th gestation week. Conclusions. APRS and DPRS could be useful in the identification and management of IUGR fetuses and in the prediction of the neonatal outcome, especially before the 34th week of gestation.
Jiang, Haiyong
2016-04-11
We present an automatic algorithm for symmetrizing facade layouts. Our method symmetrizes a given facade layout while minimally modifying the original layout. Based on the principles of symmetry in urban design, we formulate the problem of facade layout symmetrization as an optimization problem. Our system further enhances the regularity of the final layout by redistributing and aligning boxes in the layout. We demonstrate that the proposed solution can generate symmetric facade layouts efficiently. © 2015 IEEE.
Symmetrization of Facade Layouts
Jiang, Haiyong; Yan, Dong-Ming; Dong, Weiming; Wu, Fuzhang; Nan, Liangliang; Zhang, Xiaopeng
2016-01-01
We present an automatic approach for symmetrizing urban facade layouts. Our method can generate a symmetric layout through minimally modifying the original input layout. Based on the principles of symmetry in urban design, we formulate facade layout symmetrization as an optimization problem. Our method further enhances the regularity of the final layout by redistributing and aligning elements in the layout. We demonstrate that the proposed solution can effectively generate symmetric facade layouts.
Jiang, Haiyong; Dong, Weiming; Yan, Dongming; Zhang, Xiaopeng
2016-01-01
We present an automatic algorithm for symmetrizing facade layouts. Our method symmetrizes a given facade layout while minimally modifying the original layout. Based on the principles of symmetry in urban design, we formulate the problem of facade layout symmetrization as an optimization problem. Our system further enhances the regularity of the final layout by redistributing and aligning boxes in the layout. We demonstrate that the proposed solution can generate symmetric facade layouts efficiently. © 2015 IEEE.
Symmetrization of Facade Layouts
Jiang, Haiyong
2016-02-26
We present an automatic approach for symmetrizing urban facade layouts. Our method can generate a symmetric layout through minimally modifying the original input layout. Based on the principles of symmetry in urban design, we formulate facade layout symmetrization as an optimization problem. Our method further enhances the regularity of the final layout by redistributing and aligning elements in the layout. We demonstrate that the proposed solution can effectively generate symmetric facade layouts.
Directory of Open Access Journals (Sweden)
Rui V Simões
Full Text Available Intrauterine growth restriction (IUGR is a risk factor for abnormal neurodevelopment. We studied a rabbit model of IUGR by magnetic resonance imaging (MRI and spectroscopy (MRS, to assess in vivo brain structural and metabolic consequences, and identify potential metabolic biomarkers for clinical translation.IUGR was induced in 3 pregnant rabbits at gestational day 25, by 40-50% uteroplacental vessel ligation in one horn; the contralateral horn was used as control. Fetuses were delivered at day 30 and weighted. A total of 6 controls and 5 IUGR pups underwent T2-w MRI and localized proton MRS within the first 8 hours of life, at 7T. Changes in brain tissue volumes and respective contributions to each MRS voxel were estimated by semi-automated registration of MRI images with a digital atlas of the rabbit brain. MRS data were used for: (i absolute metabolite quantifications, using linear fitting; (ii local temperature estimations, based on the water chemical shift; and (iii classification, using spectral pattern analysis.Lower birth weight was associated with (i smaller brain sizes, (ii slightly lower brain temperatures, and (iii differential metabolite profile changes in specific regions of the brain parenchyma. Specifically, we found estimated lower levels of aspartate and N-acetylaspartate (NAA in the cerebral cortex and hippocampus (suggesting neuronal impairment, and higher glycine levels in the striatum (possible marker of brain injury. Our results also suggest that the metabolic changes in cortical regions are more prevalent than those detected in hippocampus and striatum.IUGR was associated with brain metabolic changes in vivo, which correlate well with the neurostructural changes and neurodevelopment problems described in IUGR. Metabolic parameters could constitute non invasive biomarkers for the diagnosis and abnormal neurodevelopment of perinatal origin.
Comprehensive asynchronous symmetric rendezvous algorithm in ...
Indian Academy of Sciences (India)
Meenu Chawla
2017-11-10
Nov 10, 2017 ... Simulation results affirm that CASR algorithm performs better in terms of average time-to-rendezvous as compared ... process; neighbour discovery; symmetric rendezvous algorithm. 1. .... dezvous in finite time under the symmetric model. The CH ..... CASR algorithm in Matlab 7.11 and performed several.
Geva, Ronny; Yosipof, Rina; Eshel, Rina; Leitner, Yael; Valevski, Aviva Fattal; Harel, Shaul
2009-01-01
This long-term, prospective study evaluated repeatedly school readiness and adjustment at kindergarten and first grade of children with extreme intrauterine growth restriction (IUGR; n = 20) in relation to controls (n = 19). Methods included individual testing of cognitive competence, self-perception, motivation, loneliness and academic…
Golden, Ryan; Cho, Ilwoo
2015-01-01
In this paper, we study structure theorems of algebras of symmetric functions. Based on a certain relation on elementary symmetric polynomials generating such algebras, we consider perturbation in the algebras. In particular, we understand generators of the algebras as perturbations. From such perturbations, define injective maps on generators, which induce algebra-monomorphisms (or embeddings) on the algebras. They provide inductive structure theorems on algebras of symmetric polynomials. As...
Directory of Open Access Journals (Sweden)
VALERIE Solomon
2001-09-01
Full Text Available The study was conducted to fi ll the gap in the dearth of information on systematic approach to ascertain the severity as well as the magnitude of the constraints responsible for the sub-optimal operation of fi sh farming in Nigeria. 120 randomly selected fish farmers from a list of 186 fi sh farmers in the state were interviewed. Participatory appraisal technique and econometric technique were adopted to ascertain the most severe major constraints and also the severity index of each of the sub-constraints that are responsible for the sub-optimal aquaculture operation in the Niger Delta region of Nigeria and the cause of withdrawal from aquaculture by some fi sh farmers. The sub-constraints severity within the major constraints, across the region gave more insight into the causes of the high rate of withdrawals from aquaculture and the decline in aquaculture productivity in the region. How productive the regional aquaculture would be, even in the nearest future, would depend to a large extent on these major factors: production, marketing and advancement in related technology. Unless pragmatic approach is used to reduce the constraints responsible for the high rate of withdrawal, fi sh food security in the Niger Delta Region of Nigeria would still be elusive.
Liu, Pengbo; Mongelli, Max; Mondry, Adrian
2004-07-01
The purpose of this study is to verify by Receiver Operating Characteristics (ROC) a mathematical model supporting the hypothesis that IUGR can be diagnosed by estimating growth velocity. The ROC compare computerized simulation results with clinical data from 325 pregnant British women. Each patient had 6 consecutive ultrasound examinations for fetal abdominal circumference (fac). Customized and un-customized fetal weights were calculated according to Hadlock"s formula. IUGR was diagnosed by the clinical standard, i.e. estimated weight below the tenth percentile. Growth velocity was estimated by calculating the changes of fac (Dzfac/dt) at various time intervals from 3 to 10 weeks. Finally, ROC was used to compare the methods. At 3~4 weeks scan interval, the area under the ROC curve is 0.68 for customized data and 0.66 for the uncustomized data with 95% confidence interval. Comparison between simulation data and real pregnancies verified that the model is clinically acceptable.
Roifman, Maian; Choufani, Sanaa; Turinsky, Andrei L; Drewlo, Sascha; Keating, Sarah; Brudno, Michael; Kingdom, John; Weksberg, Rosanna
2016-01-01
Intrauterine growth restriction (IUGR), which refers to reduced fetal growth in the context of placental insufficiency, is etiologically heterogeneous. IUGR is associated not only with perinatal morbidity and mortality but also with adult-onset disorders, such as cardiovascular disease and diabetes, posing a major health burden. Placental epigenetic dysregulation has been proposed as one mechanism that causes IUGR; however, the spectrum of epigenetic pathophysiological mechanisms leading to IUGR remains to be elucidated. Monozygotic monochorionic twins are particularly affected by IUGR, in the setting of severe discordant growth. Because monozygotic twins have the same genotype at conception and a shared maternal environment, they provide an ideal model system for studying epigenetic dysregulation of the placenta. We compared genome-wide placental DNA methylation patterns of severely growth-discordant twins to identify novel candidate genes for IUGR. Snap-frozen placental samples for eight severely growth-discordant monozygotic monochorionic twin pairs were obtained at delivery from each twin. A high-resolution DNA methylation array platform was used to identify methylation differences between IUGR and normal twins. Our analysis revealed differentially methylated regions in the promoters of eight genes: DECR1, ZNF300, DNAJA4, CCL28, LEPR, HSPA1A/L, GSTO1, and GNE. The largest methylation differences between the two groups were in the promoters of DECR1 and ZNF300. The significance of these group differences was independently validated by bisulfite pyrosequencing, implicating aberrations in fatty acid beta oxidation and transcriptional regulation, respectively. Further analysis of the array data identified methylation changes most prominently affecting the Wnt and cadherin pathways in the IUGR cohort. Our results suggest that IUGR in monozygotic twins is associated with impairments in lipid metabolism and transcriptional regulation as well as cadherin and Wnt
Centrioles in Symmetric Spaces
Quast, Peter
2011-01-01
We describe all centrioles in irreducible simply connected pointed symmetric spaces of compact type in terms of the root system of the ambient space, and we study some geometric properties of centrioles.
A symmetrical rail accelerator
International Nuclear Information System (INIS)
Igenbergs, E.
1991-01-01
This paper reports on the symmetrical rail accelerator that has four rails, which are arranged symmetrically around the bore. The opposite rails have the same polarity and the adjacent rails the opposite polarity. In this configuration the radial force acting upon the individual rails is significantly smaller than in a conventional 2-rail configuration and a plasma armature is focussed towards the axis of the barrel. Experimental results indicate a higher efficiency compared to a conventional rail accelerator
International Nuclear Information System (INIS)
Matsuki, Takayuki
1976-01-01
Symmetric eikonal expansion for the scattering amplitude is formulated for nonrelativistic and relativistic potential scatterings and also for the quantum field theory. The first approximations coincide with those of Levy and Sucher. The obtained scattering amplitudes are time reversal invariant for all cases and are crossing symmetric for the quantum field theory in each order of approximation. The improved eikonal phase introduced by Levy and Sucher is also derived from the different approximation scheme from the above. (auth.)
International Nuclear Information System (INIS)
2003-01-01
The International Atomic Energy Agency (IAEA) at its Headquarters in Vienna convened a consultants meeting from 9-13 December, 2002, to provide the Agency current insights into the application of nuclear and isotopic techniques as tool to support studies aimed at assessing the causes of Intrauterine Growth Retardation (IUGR). The consultants were: Dr. B. Caballero, Dr. D. Labadarios, Dr. G. Carroli, Dr. L.S. Bakketeig and Dr. P.T.V Nair. Representatives from the World Health Organization (WHO), Dr. G. Glugston and Dr. S. Khanum, were present as observers during the initial part of the meeting. Given the Consultants' areas of expertise and the topics covered in the discussions, the scope of the Meeting was modified to 'The application of isotopic and nuclear techniques to address the problem of intrauterine growth retardation (IUGR) in populations from developing countries'. The objectives of the meeting were to: (i) Evaluate the overall scope of a new co-ordinated research project (CRP) and suggest options for specific areas of research within that scope; (ii) Examine the applicability of nuclear and isotope based techniques in researches related to practical approaches for monitoring maternal weight and weight gain during pregnancy (e.g. body composition and energy balance assessment); (iii) Establish harmonised methods and criteria for appropriate weight gain and foetal growth charts for pregnant women in developing countries; (iv) Suggest approaches to assess the effectiveness of nutrition interventions aimed at reducing IUGR and its consequences. This meeting benefited from the broad areas of experience of scientists from both developed and developing countries. Their expertise in the use of isotopes and nuclear techniques, and in studies on human nutrition, epidemiology, IUGR, Low birth weight and undernutrition provided the advocacy and approaches to fellow in the application of nuclear and isotopic techniques as part of maternal malnutrition and IUGR studies
Multiparty symmetric sum types
DEFF Research Database (Denmark)
Nielsen, Lasse; Yoshida, Nobuko; Honda, Kohei
2010-01-01
This paper introduces a new theory of multiparty session types based on symmetric sum types, by which we can type non-deterministic orchestration choice behaviours. While the original branching type in session types can represent a choice made by a single participant and accepted by others...... determining how the session proceeds, the symmetric sum type represents a choice made by agreement among all the participants of a session. Such behaviour can be found in many practical systems, including collaborative workflow in healthcare systems for clinical practice guidelines (CPGs). Processes...... with the symmetric sums can be embedded into the original branching types using conductor processes. We show that this type-driven embedding preserves typability, satisfies semantic soundness and completeness, and meets the encodability criteria adapted to the typed setting. The theory leads to an efficient...
Counting with symmetric functions
Mendes, Anthony
2015-01-01
This monograph provides a self-contained introduction to symmetric functions and their use in enumerative combinatorics. It is the first book to explore many of the methods and results that the authors present. Numerous exercises are included throughout, along with full solutions, to illustrate concepts and also highlight many interesting mathematical ideas. The text begins by introducing fundamental combinatorial objects such as permutations and integer partitions, as well as generating functions. Symmetric functions are considered in the next chapter, with a unique emphasis on the combinatorics of the transition matrices between bases of symmetric functions. Chapter 3 uses this introductory material to describe how to find an assortment of generating functions for permutation statistics, and then these techniques are extended to find generating functions for a variety of objects in Chapter 4. The next two chapters present the Robinson-Schensted-Knuth algorithm and a method for proving Pólya’s enu...
Symmetric Tensor Decomposition
DEFF Research Database (Denmark)
Brachat, Jerome; Comon, Pierre; Mourrain, Bernard
2010-01-01
We present an algorithm for decomposing a symmetric tensor, of dimension n and order d, as a sum of rank-1 symmetric tensors, extending the algorithm of Sylvester devised in 1886 for binary forms. We recall the correspondence between the decomposition of a homogeneous polynomial in n variables...... of polynomial equations of small degree in non-generic cases. We propose a new algorithm for symmetric tensor decomposition, based on this characterization and on linear algebra computations with Hankel matrices. The impact of this contribution is two-fold. First it permits an efficient computation...... of the decomposition of any tensor of sub-generic rank, as opposed to widely used iterative algorithms with unproved global convergence (e.g. Alternate Least Squares or gradient descents). Second, it gives tools for understanding uniqueness conditions and for detecting the rank....
Energy Technology Data Exchange (ETDEWEB)
Xu, D. [Department of Pharmacology, Basic Medical School of Wuhan University, Wuhan 430071 (China); Research Center of Food and Drug Evaluation, Wuhan University, Wuhan 430071 (China); Wu, Y.; Liu, F.; Liu, Y.S.; Shen, L.; Lei, Y.Y.; Liu, J. [Department of Pharmacology, Basic Medical School of Wuhan University, Wuhan 430071 (China); Ping, J. [Department of Pharmacology, Basic Medical School of Wuhan University, Wuhan 430071 (China); Research Center of Food and Drug Evaluation, Wuhan University, Wuhan 430071 (China); Qin, J. [Department of Orthopedic Surgery, Zhongnan Hospital of Wuhan University, Wuhan 430071 (China); Zhang, C. [Department of Pharmacology, Basic Medical School of Wuhan University, Wuhan 430071 (China); Chen, L.B. [Department of Orthopedic Surgery, Zhongnan Hospital of Wuhan University, Wuhan 430071 (China); Magdalou, J. [UMR 7561 CNRS-Nancy Université, Faculté de Médicine, Vandoeuvre-lès-Nancy (France); Wang, H., E-mail: wanghui19@whu.edu.cn [Department of Pharmacology, Basic Medical School of Wuhan University, Wuhan 430071 (China); Research Center of Food and Drug Evaluation, Wuhan University, Wuhan 430071 (China)
2012-11-01
Caffeine is a definite factor of intrauterine growth retardation (IUGR). Previously, we have confirmed that prenatal caffeine ingestion inhibits the development of hypothalamic–pituitary–adrenal (HPA) axis, and alters the glucose and lipid metabolism in IUGR fetal rats. In this study, we aimed to verify a programmed alteration of neuroendocrine metabolism in prenatal caffeine ingested-offspring rats. The results showed that prenatal caffeine (120 mg/kg.day) ingestion caused low body weight and high IUGR rate of pups; the concentrations of blood adrenocorticotropic hormone (ACTH) and corticosterone in caffeine group were significantly increased in the early postnatal period followed by falling in late stage; the level of blood glucose was unchanged, while blood total cholesterol (TCH) and triglyceride (TG) were markedly enhanced in adult. After chronic stress, the concentrations and the gain rates of blood ACTH and corticosterone were obviously increased, meanwhile, the blood glucose increased while the TCH and TG decreased in caffeine group. Further, the hippocampal mineralocorticoid receptor (MR) expression in caffeine group was initially decreased and subsequently increased after birth. After chronic stress, the 11β-hydroxysteroid dehydrogenase-1, glucocorticoid receptor (GR), MR as well as the MR/GR ratio were all significantly decreased. These results suggested that prenatal caffeine ingestion induced the dysfunction of HPA axis and associated neuroendocrine metabolic programmed alteration in IUGR offspring rats, which might be related with the functional injury of hippocampus. These observations provide a valuable experimental basis for explaining the susceptibility of IUGR offspring to metabolic syndrome and associated diseases. -- Highlights: ► Prenatal caffeine ingestion induced HPA axis dysfunction in IUGR offspring rats. ► Caffeine induced a neuroendocrine metabolic programmed alteration in offspring rats. ► Caffeine induced a functional injury
International Nuclear Information System (INIS)
Xu, D.; Wu, Y.; Liu, F.; Liu, Y.S.; Shen, L.; Lei, Y.Y.; Liu, J.; Ping, J.; Qin, J.; Zhang, C.; Chen, L.B.; Magdalou, J.; Wang, H.
2012-01-01
Caffeine is a definite factor of intrauterine growth retardation (IUGR). Previously, we have confirmed that prenatal caffeine ingestion inhibits the development of hypothalamic–pituitary–adrenal (HPA) axis, and alters the glucose and lipid metabolism in IUGR fetal rats. In this study, we aimed to verify a programmed alteration of neuroendocrine metabolism in prenatal caffeine ingested-offspring rats. The results showed that prenatal caffeine (120 mg/kg.day) ingestion caused low body weight and high IUGR rate of pups; the concentrations of blood adrenocorticotropic hormone (ACTH) and corticosterone in caffeine group were significantly increased in the early postnatal period followed by falling in late stage; the level of blood glucose was unchanged, while blood total cholesterol (TCH) and triglyceride (TG) were markedly enhanced in adult. After chronic stress, the concentrations and the gain rates of blood ACTH and corticosterone were obviously increased, meanwhile, the blood glucose increased while the TCH and TG decreased in caffeine group. Further, the hippocampal mineralocorticoid receptor (MR) expression in caffeine group was initially decreased and subsequently increased after birth. After chronic stress, the 11β-hydroxysteroid dehydrogenase-1, glucocorticoid receptor (GR), MR as well as the MR/GR ratio were all significantly decreased. These results suggested that prenatal caffeine ingestion induced the dysfunction of HPA axis and associated neuroendocrine metabolic programmed alteration in IUGR offspring rats, which might be related with the functional injury of hippocampus. These observations provide a valuable experimental basis for explaining the susceptibility of IUGR offspring to metabolic syndrome and associated diseases. -- Highlights: ► Prenatal caffeine ingestion induced HPA axis dysfunction in IUGR offspring rats. ► Caffeine induced a neuroendocrine metabolic programmed alteration in offspring rats. ► Caffeine induced a functional injury
Distributed Searchable Symmetric Encryption
Bösch, C.T.; Peter, Andreas; Leenders, Bram; Lim, Hoon Wei; Tang, Qiang; Wang, Huaxiong; Hartel, Pieter H.; Jonker, Willem
Searchable Symmetric Encryption (SSE) allows a client to store encrypted data on a storage provider in such a way, that the client is able to search and retrieve the data selectively without the storage provider learning the contents of the data or the words being searched for. Practical SSE schemes
Directory of Open Access Journals (Sweden)
Marta Vazquez-Gomez
Full Text Available Hydroxytyrosol is a polyphenol with antioxidant, metabolism-regulatory, anti-inflammatory and immuno-modulatory properties. The present study aimed to determine whether supplementing the maternal diet with hydroxytyrosol during pregnancy can improve pre- and early post-natal developmental patterns and metabolic traits of the offspring. Experiment was performed in Iberian sows fed a restricted diet in order to increase the risk of IUGR. Ten sows were treated daily with 1.5 mg of hydroxytyrosol per kg of feed between Day 35 of pregnancy (30% of total gestational period until delivery whilst 10 animals were left untreated as controls. Number and weight of offspring were assessed at birth, on post-natal Day 15 and at weaning (25 days-old. At weaning, body composition and plasma indexes of glucose and lipids were measured. Treatment with hydroxytyrosol was associated with higher mean birth weight, lower incidence of piglets with low birth weight. Afterwards, during the lactation period, piglets in the treated group showed a higher body-weight than control piglets; such effects were even stronger in the most prolific litters. These results suggest that maternal supplementation with hydroxytyrosol may improve pre- and early post-natal development of offspring in pregnancies at risk of IUGR.
Roth, Christian J.; Haeussner, Eva; Ruebelmann, Tanja; Koch, Franz V.; Schmitz, Christoph; Frank, Hans-Georg; Wall, Wolfgang A.
2017-01-01
Ischemic placental disease is a concept that links intrauterine growth retardation (IUGR) and preeclampsia (PE) back to insufficient remodeling of uterine spiral arteries. The rheological consequences of insufficient remodeling of uterine spiral arteries were hypothesized to mediate the considerably later manifestation of obstetric disease. However, the micro-rheology in the intervillous space (IVS) cannot be examined clinically and rheological animal models of the human IVS do not exist. Thus, an in silico approach was implemented to provide in vivo inaccessible data. The morphology of a spiral artery and the inflow region of the IVS were three-dimensionally reconstructed to provide a morphological stage for the simulations. Advanced high-end supercomputing resources were used to provide blood flow simulations at high spatial resolution. Our simulations revealed turbulent blood flow (high-velocity jets and vortices) combined with elevated blood pressure in the IVS and increased wall shear stress at the villous surface in conjunction with insufficient spiral artery remodeling only. Post-hoc histological analysis of uterine veins showed evidence of increased trophoblast shedding in an IUGR placenta. Our data support that rheological alteration in the IVS is a relevant mechanism linking ischemic placental disease to altered structural integrity and function of the placenta.
Chen, Yan; Feng, Huijuan; Ma, Jiayao; Peng, Rui; You, Zhong
2016-06-01
The traditional waterbomb origami, produced from a pattern consisting of a series of vertices where six creases meet, is one of the most widely used origami patterns. From a rigid origami viewpoint, it generally has multiple degrees of freedom, but when the pattern is folded symmetrically, the mobility reduces to one. This paper presents a thorough kinematic investigation on symmetric folding of the waterbomb pattern. It has been found that the pattern can have two folding paths under certain circumstance. Moreover, the pattern can be used to fold thick panels. Not only do the additional constraints imposed to fold the thick panels lead to single degree of freedom folding, but the folding process is also kinematically equivalent to the origami of zero-thickness sheets. The findings pave the way for the pattern being readily used to fold deployable structures ranging from flat roofs to large solar panels.
Rome, J.A.; Harris, J.H.
1984-01-01
A fusion reactor device is provided in which the magnetic fields for plasma confinement in a toroidal configuration is produced by a plurality of symmetrical modular coils arranged to form a symmetric modular torsatron referred to as a symmotron. Each of the identical modular coils is helically deformed and comprise one field period of the torsatron. Helical segments of each coil are connected by means of toroidally directed windbacks which may also provide part of the vertical field required for positioning the plasma. The stray fields of the windback segments may be compensated by toroidal coils. A variety of magnetic confinement flux surface configurations may be produced by proper modulation of the winding pitch of the helical segments of the coils, as in a conventional torsatron, winding the helix on a noncircular cross section and varying the poloidal and radial location of the windbacks and the compensating toroidal ring coils.
Seferovic, Maxim D; Goodspeed, Danielle M; Chu, Derrick M; Krannich, Laura A; Gonzalez-Rodriguez, Pablo J; Cox, James E; Aagaard, Kjersti M
2015-06-01
Metabolic syndrome (MetS), following intrauterine growth restriction (IUGR), is epigenetically heritable. Recently, we abrogated the F2 adult phenotype with essential nutrient supplementation (ENS) of intermediates along the 1-carbon pathway. With the use of the same grandparental uterine artery ligation model, we profiled the F2 serum metabolome at weaning [postnatal day (d)21; n = 76] and adulthood (d160; n = 12) to test if MetS is preceded by alterations in the metabolome. Indicative of developmentally programmed MetS, adult F2, formerly IUGR rats, were obese (621 vs. 461 g; P metabolome at weaning (randomForest analysis; class error metabolome accompany heritable IUGR, precede adult-onset MetS, and are partially amenable to dietary intervention. © FASEB.
Symmetric vectors and algebraic classification
International Nuclear Information System (INIS)
Leibowitz, E.
1980-01-01
The concept of symmetric vector field in Riemannian manifolds, which arises in the study of relativistic cosmological models, is analyzed. Symmetric vectors are tied up with the algebraic properties of the manifold curvature. A procedure for generating a congruence of symmetric fields out of a given pair is outlined. The case of a three-dimensional manifold of constant curvature (''isotropic universe'') is studied in detail, with all its symmetric vector fields being explicitly constructed
Representations of locally symmetric spaces
International Nuclear Information System (INIS)
Rahman, M.S.
1995-09-01
Locally symmetric spaces in reference to globally and Hermitian symmetric Riemannian spaces are studied. Some relations between locally and globally symmetric spaces are exhibited. A lucid account of results on relevant spaces, motivated by fundamental problems, are formulated as theorems and propositions. (author). 10 refs
Holographic Spherically Symmetric Metrics
Petri, Michael
The holographic principle (HP) conjectures, that the maximum number of degrees of freedom of any realistic physical system is proportional to the system's boundary area. The HP has its roots in the study of black holes. It has recently been applied to cosmological solutions. In this article we apply the HP to spherically symmetric static space-times. We find that any regular spherically symmetric object saturating the HP is subject to tight constraints on the (interior) metric, energy-density, temperature and entropy-density. Whenever gravity can be described by a metric theory, gravity is macroscopically scale invariant and the laws of thermodynamics hold locally and globally, the (interior) metric of a regular holographic object is uniquely determined up to a constant factor and the interior matter-state must follow well defined scaling relations. When the metric theory of gravity is general relativity, the interior matter has an overall string equation of state (EOS) and a unique total energy-density. Thus the holographic metric derived in this article can serve as simple interior 4D realization of Mathur's string fuzzball proposal. Some properties of the holographic metric and its possible experimental verification are discussed. The geodesics of the holographic metric describe an isotropically expanding (or contracting) universe with a nearly homogeneous matter-distribution within the local Hubble volume. Due to the overall string EOS the active gravitational mass-density is zero, resulting in a coasting expansion with Ht = 1, which is compatible with the recent GRB-data.
Symmetric extendibility of quantum states
Nowakowski, Marcin L.
2015-01-01
Studies on symmetric extendibility of quantum states become especially important in a context of analysis of one-way quantum measures of entanglement, distilabillity and security of quantum protocols. In this paper we analyse composite systems containing a symmetric extendible part with a particular attention devoted to one-way security of such systems. Further, we introduce a new one-way monotone based on the best symmetric approximation of quantum state. We underpin those results with geome...
Xu, D; Wu, Y; Liu, F; Liu, Y S; Shen, L; Lei, Y Y; Liu, J; Ping, J; Qin, J; Zhang, C; Chen, L B; Magdalou, J; Wang, H
2012-11-01
Caffeine is a definite factor of intrauterine growth retardation (IUGR). Previously, we have confirmed that prenatal caffeine ingestion inhibits the development of hypothalamic-pituitary-adrenal (HPA) axis, and alters the glucose and lipid metabolism in IUGR fetal rats. In this study, we aimed to verify a programmed alteration of neuroendocrine metabolism in prenatal caffeine ingested-offspring rats. The results showed that prenatal caffeine (120 mg/kg.day) ingestion caused low body weight and high IUGR rate of pups; the concentrations of blood adrenocorticotropic hormone (ACTH) and corticosterone in caffeine group were significantly increased in the early postnatal period followed by falling in late stage; the level of blood glucose was unchanged, while blood total cholesterol (TCH) and triglyceride (TG) were markedly enhanced in adult. After chronic stress, the concentrations and the gain rates of blood ACTH and corticosterone were obviously increased, meanwhile, the blood glucose increased while the TCH and TG decreased in caffeine group. Further, the hippocampal mineralocorticoid receptor (MR) expression in caffeine group was initially decreased and subsequently increased after birth. After chronic stress, the 11β-hydroxysteroid dehydrogenase-1, glucocorticoid receptor (GR), MR as well as the MR/GR ratio were all significantly decreased. These results suggested that prenatal caffeine ingestion induced the dysfunction of HPA axis and associated neuroendocrine metabolic programmed alteration in IUGR offspring rats, which might be related with the functional injury of hippocampus. These observations provide a valuable experimental basis for explaining the susceptibility of IUGR offspring to metabolic syndrome and associated diseases. Copyright © 2012 Elsevier Inc. All rights reserved.
International Nuclear Information System (INIS)
Burtraw, Dallas; Palmer, Karen; Kahn, Danny
2010-01-01
How to set policy in the presence of uncertainty has been central in debates over climate policy. Concern about costs has motivated the proposal for a cap-and-trade program for carbon dioxide, with a 'safety valve' that would mitigate against spikes in the cost of emission reductions by introducing additional emission allowances into the market when marginal costs rise above the specified allowance price level. We find two significant problems, both stemming from the asymmetry of an instrument that mitigates only against a price increase. One is that most important examples of price volatility in cap-and-trade programs have occurred not when prices spiked, but instead when allowance prices collapsed. Second, a single-sided safety valve may have unintended consequences for investment. We illustrate that a symmetric safety valve provides environmental and welfare improvements relative to the conventional one-sided approach.
Directory of Open Access Journals (Sweden)
Giuseppe Dattoli
1996-05-01
Full Text Available q analog of bessel functions, symmetric under the interchange of q and q^ −1 are introduced. The definition is based on the generating function realized as product of symmetric q-exponential functions with appropriate arguments. Symmetric q-Bessel function are shown to satisfy various identities as well as second-order q-differential equations, which in the limit q → 1 reproduce those obeyed by the usual cylindrical Bessel functions. A brief discussion on the possible algebraic setting for symmetric q-Bessel functions is also provided.
Conformally symmetric traversable wormholes
International Nuclear Information System (INIS)
Boehmer, Christian G.; Harko, Tiberiu; Lobo, Francisco S. N.
2007-01-01
Exact solutions of traversable wormholes are found under the assumption of spherical symmetry and the existence of a nonstatic conformal symmetry, which presents a more systematic approach in searching for exact wormhole solutions. In this work, a wide variety of solutions are deduced by considering choices for the form function, a specific linear equation of state relating the energy density and the pressure anisotropy, and various phantom wormhole geometries are explored. A large class of solutions impose that the spatial distribution of the exotic matter is restricted to the throat neighborhood, with a cutoff of the stress-energy tensor at a finite junction interface, although asymptotically flat exact solutions are also found. Using the 'volume integral quantifier', it is found that the conformally symmetric phantom wormhole geometries may, in principle, be constructed by infinitesimally small amounts of averaged null energy condition violating matter. Considering the tidal acceleration traversability conditions for the phantom wormhole geometry, specific wormhole dimensions and the traversal velocity are also deduced
Lewis, Joshua B; Mejia, Camilo; Jordan, Clinton; Monson, Troy D; Bodine, Jared S; Dunaway, Todd M; Egbert, Kaleb M; Lewis, Adam L; Wright, Tanner J; Ogden, K Connor; Broberg, Dallin S; Hall, Parker D; Nelson, Shawn M; Hirschi, Kelsey M; Reynolds, Paul R; Arroyo, Juan A
2017-12-01
Intrauterine growth restriction (IUGR) is a disease affecting 10% of all pregnancies. IUGR is associated with maternal, fetal, or placental abnormalities. Studies investigating the effects of secondhand smoke (SHS) exposure and IUGR are limited. The receptor for advanced glycation end-products (RAGE) is a pro-inflammatory transmembrane receptor increased by SHS in the placenta. We tested the hypothesis that inhibition of RAGE during SHS exposure protects from smoke-induced IUGR. C57BL/6 mice were exposed to SHS or SHS + semi-synthetic glycosaminoglycan ethers (SAGEs) known to inhibit RAGE signaling. Trophoblast cells were treated with cigarette smoke extract (CSE) with or without SAGEs in order to address the effects of RAGE inhibition during trophoblast invasion in vitro. SHS-treated mice demonstrated a significant reduction in fetal weight (7.35-fold, P ≤ 0.0001) and placental weight (1.13-fold, P ≤ 0.0001) compared with controls. Mice co-treated with SHS and SAGEs were protected from SHS-induced fetal weights decreases. SHS treatment of C57BL/6 mice activated placental extracellular signal-regulated kinase (ERK) (3.0-fold, P ≤ 0.05), JNK (2.4-fold, P ≤ 0.05) and p38 (2.1-fold, P ≤ 0.05) and the expression of inflammatory mediators including TNF-α (1.34-fold, P ≤ 0.05) and IL-1β (1.03-fold, P ≤ 0.05). SHS-mediated activation of these molecules was reduced to basal levels when SAGE was co-administered. Invasion of trophoblast cells decreased 92% (P < 0.002) when treated with CSE and CSE-mediated invasion was completely reversed by SAGEs. We conclude that RAGE inhibition protects against fetal weight loss during SHS-induced IUGR. These studies provide insight into tobacco-mediated IUGR development and clarify avenues that may be helpful in the alleviation of placental complications.
Symmetric vs. asymmetric punishment regimes for bribery
Engel, Christoph; Goerg, Sebastian J.; Yu, Gaoneng
2012-01-01
In major legal orders such as UK, the U.S., Germany, and France, bribers and recipients face equally severe criminal sanctions. In contrast, countries like China, Russia, and Japan treat the briber more mildly. Given these differences between symmetric and asymmetric punishment regimes for bribery, one may wonder which punishment strategy is more effective in curbing corruption. For this purpose, we designed and ran a lab experiment in Bonn (Germany) and Shanghai (China) with exactly the same...
Spherically symmetric charged compact stars
Energy Technology Data Exchange (ETDEWEB)
Maurya, S.K. [University of Nizwa, Department of Mathematical and Physical Sciences, College of Arts and Science, Nizwa (Oman); Gupta, Y.K. [Jaypee Institute of Information Technology University, Department of Mathematics, Noida, Uttar Pradesh (India); Ray, Saibal [Government College of Engineering and Ceramic Technology, Department of Physics, Kolkata, West Bengal (India); Chowdhury, Sourav Roy [Seth Anandaram Jaipuria College, Department of Physics, Kolkata, West Bengal (India)
2015-08-15
In this article we consider the static spherically symmetric metric of embedding class 1. When solving the Einstein-Maxwell field equations we take into account the presence of ordinary baryonic matter together with the electric charge. Specific new charged stellar models are obtained where the solutions are entirely dependent on the electromagnetic field, such that the physical parameters, like density, pressure etc. do vanish for the vanishing charge. We systematically analyze altogether the three sets of Solutions I, II, and III of the stellar models for a suitable functional relation of ν(r). However, it is observed that only the Solution I provides a physically valid and well-behaved situation, whereas the Solutions II and III are not well behaved and hence not included in the study. Thereafter it is exclusively shown that the Solution I can pass through several standard physical tests performed by us. To validate the solution set presented here a comparison has also been made with that of the compact stars, like RX J 1856 - 37, Her X - 1, PSR 1937+21, PSRJ 1614-2230, and PSRJ 0348+0432, and we have shown the feasibility of the models. (orig.)
Exact axially symmetric galactic dynamos
Henriksen, R. N.; Woodfinden, A.; Irwin, J. A.
2018-05-01
We give a selection of exact dynamos in axial symmetry on a galactic scale. These include some steady examples, at least one of which is wholly analytic in terms of simple functions and has been discussed elsewhere. Most solutions are found in terms of special functions, such as associated Lagrange or hypergeometric functions. They may be considered exact in the sense that they are known to any desired accuracy in principle. The new aspect developed here is to present scale-invariant solutions with zero resistivity that are self-similar in time. The time dependence is either a power law or an exponential factor, but since the geometry of the solution is self-similar in time we do not need to fix a time to study it. Several examples are discussed. Our results demonstrate (without the need to invoke any other mechanisms) X-shaped magnetic fields and (axially symmetric) magnetic spiral arms (both of which are well observed and documented) and predict reversing rotation measures in galaxy haloes (now observed in the CHANG-ES sample) as well as the fact that planar magnetic spirals are lifted into the galactic halo.
Mesotherapy for benign symmetric lipomatosis.
Hasegawa, Toshio; Matsukura, Tomoyuki; Ikeda, Shigaku
2010-04-01
Benign symmetric lipomatosis, also known as Madelung disease, is a rare disorder characterized by fat distribution around the shoulders, arms, and neck in the context of chronic alcoholism. Complete excision of nonencapsulated lipomas is difficult. However, reports describing conservative therapeutic measures for lipomatosis are rare. The authors present the case of a 42-year-old man with a diagnosis of benign symmetric lipomatosis who had multiple, large, symmetrical masses in his neck. Multiple phosphatidylcholine injections in the neck were administered 4 weeks apart, a total of seven times to achieve lipolysis. The patient's lipomatosis improved in response to the injections, and he achieved good cosmetic results. Intralesional injection, termed mesotherapy, using phosphatidylcholine is a potentially effective therapy for benign symmetric lipomatosis that should be reconsidered as a therapeutic option for this disease.
Looking for symmetric Bell inequalities
Bancal, Jean-Daniel; Gisin, Nicolas; Pironio, Stefano
2010-01-01
Finding all Bell inequalities for a given number of parties, measurement settings and measurement outcomes is in general a computationally hard task. We show that all Bell inequalities which are symmetric under the exchange of parties can be found by examining a symmetrized polytope which is simpler than the full Bell polytope. As an illustration of our method, we generate 238 885 new Bell inequalities and 1085 new Svetlichny inequalities. We find, in particular, facet inequalities for Bell e...
Factored Facade Acquisition using Symmetric Line Arrangements
Ceylan, Duygu
2012-05-01
We introduce a novel framework for image-based 3D reconstruction of urban buildings based on symmetry priors. Starting from image-level edges, we generate a sparse and approximate set of consistent 3D lines. These lines are then used to simultaneously detect symmetric line arrangements while refining the estimated 3D model. Operating both on 2D image data and intermediate 3D feature representations, we perform iterative feature consolidation and effective outlier pruning, thus eliminating reconstruction artifacts arising from ambiguous or wrong stereo matches. We exploit non-local coherence of symmetric elements to generate precise model reconstructions, even in the presence of a significant amount of outlier image-edges arising from reflections, shadows, outlier objects, etc. We evaluate our algorithm on several challenging test scenarios, both synthetic and real. Beyond reconstruction, the extracted symmetry patterns are useful towards interactive and intuitive model manipulations.
Multiple symmetrical lipomatosis (Madelung's disease) - a case report
International Nuclear Information System (INIS)
Vieira, Marcelo Vasconcelos; Abreu, Marcelo de; Furtado, Claudia Dietz; Silveira, Marcio Fleck da; Furtado, Alvaro Porto Alegre; Genro, Carlos Horacio; Grazziotin, Rossano Ughini
2001-01-01
Multiple symmetrical lipomatosis (Madelung's disease) is a rare disorder characterized by deep accumulation of fat tissue, involving mainly the neck, shoulders and chest. This disease is associated with heavy alcohol intake and it is more common in men of Mediterranean origin. This disease can cause severe aesthetic deformities and progressive respiratory dysfunction. We report a case of a patient with multiple symmetrical lipomatosis and describe the clinical and radiological features of this disorder. (author)
Harmonic analysis on symmetric spaces
Terras, Audrey
This text explores the geometry and analysis of higher rank analogues of the symmetric spaces introduced in volume one. To illuminate both the parallels and differences of the higher rank theory, the space of positive matrices is treated in a manner mirroring that of the upper-half space in volume one. This concrete example furnishes motivation for the general theory of noncompact symmetric spaces, which is outlined in the final chapter. The book emphasizes motivation and comprehensibility, concrete examples and explicit computations (by pen and paper, and by computer), history, and, above all, applications in mathematics, statistics, physics, and engineering. The second edition includes new sections on Donald St. P. Richards’s central limit theorem for O(n)-invariant random variables on the symmetric space of GL(n, R), on random matrix theory, and on advances in the theory of automorphic forms on arithmetic groups.
Looking for symmetric Bell inequalities
International Nuclear Information System (INIS)
Bancal, Jean-Daniel; Gisin, Nicolas; Pironio, Stefano
2010-01-01
Finding all Bell inequalities for a given number of parties, measurement settings and measurement outcomes is in general a computationally hard task. We show that all Bell inequalities which are symmetric under the exchange of parties can be found by examining a symmetrized polytope which is simpler than the full Bell polytope. As an illustration of our method, we generate 238 885 new Bell inequalities and 1085 new Svetlichny inequalities. We find, in particular, facet inequalities for Bell experiments involving two parties and two measurement settings that are not of the Collins-Gisin-Linden-Massar-Popescu type.
Symmetric normalisation for intuitionistic logic
DEFF Research Database (Denmark)
Guenot, Nicolas; Straßburger, Lutz
2014-01-01
We present two proof systems for implication-only intuitionistic logic in the calculus of structures. The first is a direct adaptation of the standard sequent calculus to the deep inference setting, and we describe a procedure for cut elimination, similar to the one from the sequent calculus......, but using a non-local rewriting. The second system is the symmetric completion of the first, as normally given in deep inference for logics with a DeMorgan duality: all inference rules have duals, as cut is dual to the identity axiom. We prove a generalisation of cut elimination, that we call symmetric...
Diagrams for symmetric product orbifolds
International Nuclear Information System (INIS)
Pakman, Ari; Rastelli, Leonardo; Razamat, Shlomo S.
2009-01-01
We develop a diagrammatic language for symmetric product orbifolds of two-dimensional conformal field theories. Correlation functions of twist operators are written as sums of diagrams: each diagram corresponds to a branched covering map from a surface where the fields are single-valued to the base sphere where twist operators are inserted. This diagrammatic language facilitates the study of the large N limit and makes more transparent the analogy between symmetric product orbifolds and free non-abelian gauge theories. We give a general algorithm to calculate the leading large N contribution to four-point correlators of twist fields.
Looking for symmetric Bell inequalities
Energy Technology Data Exchange (ETDEWEB)
Bancal, Jean-Daniel; Gisin, Nicolas [Group of Applied Physics, University of Geneva, 20 rue de l' Ecole-de Medecine, CH-1211 Geneva 4 (Switzerland); Pironio, Stefano, E-mail: jean-daniel.bancal@unige.c [Laboratoire d' Information Quantique, Universite Libre de Bruxelles (Belgium)
2010-09-24
Finding all Bell inequalities for a given number of parties, measurement settings and measurement outcomes is in general a computationally hard task. We show that all Bell inequalities which are symmetric under the exchange of parties can be found by examining a symmetrized polytope which is simpler than the full Bell polytope. As an illustration of our method, we generate 238 885 new Bell inequalities and 1085 new Svetlichny inequalities. We find, in particular, facet inequalities for Bell experiments involving two parties and two measurement settings that are not of the Collins-Gisin-Linden-Massar-Popescu type.
Symmetric autocompensating quantum key distribution
Walton, Zachary D.; Sergienko, Alexander V.; Levitin, Lev B.; Saleh, Bahaa E. A.; Teich, Malvin C.
2004-08-01
We present quantum key distribution schemes which are autocompensating (require no alignment) and symmetric (Alice and Bob receive photons from a central source) for both polarization and time-bin qubits. The primary benefit of the symmetric configuration is that both Alice and Bob may have passive setups (neither Alice nor Bob is required to make active changes for each run of the protocol). We show that both the polarization and the time-bin schemes may be implemented with existing technology. The new schemes are related to previously described schemes by the concept of advanced waves.
Severe cell reduction in the future brain cortex in human growth-restricted fetuses and infants
DEFF Research Database (Denmark)
Samuelsen, Grethe B; Pakkenberg, Bente; Bogdanović, Nenad
2007-01-01
with controls. The daily increase in brain cells in the future cortex was only half of that of the controls. In the 3 other developmental zones, no significant differences in cell numbers could be demonstrated. CONCLUSIONS: IUGR in humans is associated with a severe reduction in cortical growth...
Symmetric relations of finite negativity
Kaltenbaeck, M.; Winkler, H.; Woracek, H.; Forster, KH; Jonas, P; Langer, H
2006-01-01
We construct and investigate a space which is related to a symmetric linear relation S of finite negativity on an almost Pontryagin space. This space is the indefinite generalization of the completion of dom S with respect to (S.,.) for a strictly positive S on a Hilbert space.
Tilting-connected symmetric algebras
Aihara, Takuma
2010-01-01
The notion of silting mutation was introduced by Iyama and the author. In this paper we mainly study silting mutation for self-injective algebras and prove that any representation-finite symmetric algebra is tilting-connected. Moreover we give some sufficient conditions for a Bongartz-type Lemma to hold for silting objects.
Symmetric group representations and Z
Adve, Anshul; Yong, Alexander
2017-01-01
We discuss implications of the following statement about the representation theory of symmetric groups: every integer appears infinitely often as an irreducible character evaluation, and every nonnegative integer appears infinitely often as a Littlewood-Richardson coefficient and as a Kronecker coefficient.
Symmetric Key Authentication Services Revisited
Crispo, B.; Popescu, B.C.; Tanenbaum, A.S.
2004-01-01
Most of the symmetric key authentication schemes deployed today are based on principles introduced by Needham and Schroeder [15] more than twenty years ago. However, since then, the computing environment has evolved from a LAN-based client-server world to include new paradigms, including wide area
Quantum systems and symmetric spaces
International Nuclear Information System (INIS)
Olshanetsky, M.A.; Perelomov, A.M.
1978-01-01
Certain class of quantum systems with Hamiltonians related to invariant operators on symmetric spaces has been investigated. A number of physical facts have been derived as a consequence. In the classical limit completely integrable systems related to root systems are obtained
The symmetric longest queue system
van Houtum, Geert-Jan; Adan, Ivo; van der Wal, Jan
1997-01-01
We derive the performance of the exponential symmetric longest queue system from two variants: a longest queue system with Threshold Rejection of jobs and one with Threshold Addition of jobs. It is shown that these two systems provide lower and upper bounds for the performance of the longest queue
Symmetric imaging findings in neuroradiology
International Nuclear Information System (INIS)
Zlatareva, D.
2015-01-01
Full text: Learning objectives: to make a list of diseases and syndromes which manifest as bilateral symmetric findings on computed tomography and magnetic resonance imaging; to discuss the clinical and radiological differential diagnosis for these diseases; to explain which of these conditions necessitates urgent therapy and when additional studies and laboratory can precise diagnosis. There is symmetry in human body and quite often we compare the affected side to the normal one but in neuroradiology we might have bilateral findings which affected pair structures or corresponding anatomic areas. It is very rare when clinical data prompt diagnosis. Usually clinicians suspect such an involvement but Ct and MRI can reveal symmetric changes and are one of the leading diagnostic tool. The most common location of bilateral findings is basal ganglia and thalamus. There are a number of diseases affecting these structures symmetrically: metabolic and systemic diseases, intoxication, neurodegeneration and vascular conditions, toxoplasmosis, tumors and some infections. Malformations of cortical development and especially bilateral perisylvian polymicrogyria requires not only exact report on the most affected parts but in some cases genetic tests or combination with other clinical symptoms. In the case of herpes simplex encephalitis bilateral temporal involvement is common and this finding very often prompt therapy even before laboratory results. Posterior reversible encephalopathy syndrome (PReS) and some forms of hypoxic ischemic encephalopathy can lead to symmetric changes. In these acute conditions MR plays a crucial role not only in diagnosis but also in monitoring of the therapeutic effect. Patients with neurofibromatosis type 1 or type 2 can demonstrate bilateral optic glioma combined with spinal neurofibroma and bilateral acoustic schwanoma respectively. Mirror-image aneurysm affecting both internal carotid or middle cerebral arteries is an example of symmetry in
Parity-Time Symmetric Photonics
Zhao, Han
2018-01-17
The establishment of non-Hermitian quantum mechanics (such as parity-time (PT) symmetry) stimulates a paradigmatic shift for studying symmetries of complex potentials. Owing to the convenient manipulation of optical gain and loss in analogy to the complex quantum potentials, photonics provides an ideal platform for visualization of many conceptually striking predictions from the non-Hermitian quantum theory. A rapidly developing field has emerged, namely, PT symmetric photonics, demonstrating intriguing optical phenomena including eigenstate coalescence and spontaneous PT symmetry breaking. The advance of quantum physics, as the feedback, provides photonics with brand-new paradigms to explore the entire complex permittivity plane for novel optical functionalities. Here, we review recent exciting breakthroughs in PT symmetric photonics while systematically presenting their underlying principles guided by non-Hermitian symmetries. The potential device applications for optical communication and computing, bio-chemical sensing, and healthcare are also discussed.
Homotheties of cylindrically symmetric static spacetimes
International Nuclear Information System (INIS)
Qadir, A.; Ziad, M.; Sharif, M.
1998-08-01
In this note we consider the homotheties of cylindrically symmetric static spacetimes. We find that we can provide a complete list of all metrics that admit non-trivial homothetic motions and are cylindrically symmetric static. (author)
Maximally Symmetric Composite Higgs Models.
Csáki, Csaba; Ma, Teng; Shu, Jing
2017-09-29
Maximal symmetry is a novel tool for composite pseudo Goldstone boson Higgs models: it is a remnant of an enhanced global symmetry of the composite fermion sector involving a twisting with the Higgs field. Maximal symmetry has far-reaching consequences: it ensures that the Higgs potential is finite and fully calculable, and also minimizes the tuning. We present a detailed analysis of the maximally symmetric SO(5)/SO(4) model and comment on its observational consequences.
On symmetric structures of order two
Directory of Open Access Journals (Sweden)
Michel Bousquet
2008-04-01
Full Text Available Let (ω n 0 < n be the sequence known as Integer Sequence A047749 http://www.research.att.com/ njas/sequences/A047749 In this paper, we show that the integer ω n enumerates various kinds of symmetric structures of order two. We first consider ternary trees having a reflexive symmetry and we relate all symmetric combinatorial objects by means of bijection. We then generalize the symmetric structures and correspondences to an infinite family of symmetric objects.
Baryon symmetric big bang cosmology
International Nuclear Information System (INIS)
Stecker, F.W.
1978-01-01
It is stated that the framework of baryon symmetric big bang (BSBB) cosmology offers our greatest potential for deducting the evolution of the Universe because its physical laws and processes have the minimum number of arbitrary assumptions about initial conditions in the big-bang. In addition, it offers the possibility of explaining the photon-baryon ratio in the Universe and how galaxies and galaxy clusters are formed. BSBB cosmology also provides the only acceptable explanation at present for the origin of the cosmic γ-ray background radiation. (author)
Symmetric functions and orthogonal polynomials
Macdonald, I G
1997-01-01
One of the most classical areas of algebra, the theory of symmetric functions and orthogonal polynomials has long been known to be connected to combinatorics, representation theory, and other branches of mathematics. Written by perhaps the most famous author on the topic, this volume explains some of the current developments regarding these connections. It is based on lectures presented by the author at Rutgers University. Specifically, he gives recent results on orthogonal polynomials associated with affine Hecke algebras, surveying the proofs of certain famous combinatorial conjectures.
Immanant Conversion on Symmetric Matrices
Directory of Open Access Journals (Sweden)
Purificação Coelho M.
2014-01-01
Full Text Available Letr Σn(C denote the space of all n χ n symmetric matrices over the complex field C. The main objective of this paper is to prove that the maps Φ : Σn(C -> Σn (C satisfying for any fixed irre- ducible characters X, X' -SC the condition dx(A +aB = dχ·(Φ(Α + αΦ(Β for all matrices A,В ε Σ„(С and all scalars a ε C are automatically linear and bijective. As a corollary of the above result we characterize all such maps Φ acting on ΣИ(С.
Directory of Open Access Journals (Sweden)
Ilona Hromadnikova
Full Text Available A nested case control study of a longitudinal cohort comparing pregnant women enrolled at 10 to 13 gestational weeks was carried out to evaluate risk assessment for preeclampsia and IUGR based on circulating placental specific C19MC microRNAs in early pregnancy.The expression of placental specific C19MC microRNAs (miR-516b-5p, miR-517-5p, miR-518b, miR-520a-5p, miR-520h, and miR-525-5p was determined in plasma samples from pregnancies that subsequently developed preeclampsia (n = 21, IUGR (n = 18, and 58 normal pregnancies using real-time PCR and comparative Ct method relative to synthetic Caenorhabditis elegans microRNA (cel-miR-39.Circulating C19MC microRNAs were up-regulated (miR-517-5p, p = 0.005; miR-518b, p = 0.013; miR-520h, p = 0.021 or showed a trend toward up-regulation in patients destined to develop preeclampsia (miR-520a-5p, p = 0.067; miR-525-5p, p = 0.073. MiR-517-5p had the best predictive performance for preeclampsia with a sensitivity of 42.9%, a specificity of 86.2%, a PPV of 52.9% and a NPV of 80.6%. The combination of all examined circulating C19MC microRNAs had no advantage over using only the miR-517-5p biomarker to predict the occurrence of preeclampsia (a sensitivity of 20.6%, a specificity of 90.8%, a PPV of 44.8%, and a NPV of 76.0%.Up-regulation of miR-517-5p, miR-518b and miR-520h was associated with a risk of later development of preeclampsia. First trimester screening of extracellular miR-517-5p identified a proportion of women with subsequent preeclampsia. No circulating C19MC microRNA biomarkers were identified that could predict later occurrence of IUGR.
Ruff, Crystal A; Faulkner, Stuart D; Rumajogee, Prakasham; Beldick, Stephanie; Foltz, Warren; Corrigan, Jennifer; Basilious, Alfred; Jiang, Shangjun; Thiyagalingam, Shanojan; Yager, Jerome Y; Fehlings, Michael G
2017-01-01
weeks of age. Furthermore, neurobehavioural testing demonstrated neuromotor impairments in animals with IUGR in paw intensities, swing speed, relative print positions, and phase dispersions. We have characterized a rodent model of IUGR and have demonstrated that the neuroanatomical and neurobehavioural deficits mirror the severity of the IUGR injury. This model has the potential to be applied to examine the pathobiology of and potential therapeutic strategies for IUGR-related brain injury. Thus, this work has potential translational relevance for the study of CP.
Directory of Open Access Journals (Sweden)
Crystal A Ruff
changes at 3 weeks of age. Furthermore, neurobehavioural testing demonstrated neuromotor impairments in animals with IUGR in paw intensities, swing speed, relative print positions, and phase dispersions.We have characterized a rodent model of IUGR and have demonstrated that the neuroanatomical and neurobehavioural deficits mirror the severity of the IUGR injury. This model has the potential to be applied to examine the pathobiology of and potential therapeutic strategies for IUGR-related brain injury. Thus, this work has potential translational relevance for the study of CP.
Geometric inequalities for axially symmetric black holes
International Nuclear Information System (INIS)
Dain, Sergio
2012-01-01
A geometric inequality in general relativity relates quantities that have both a physical interpretation and a geometrical definition. It is well known that the parameters that characterize the Kerr-Newman black hole satisfy several important geometric inequalities. Remarkably enough, some of these inequalities also hold for dynamical black holes. This kind of inequalities play an important role in the characterization of the gravitational collapse; they are closely related with the cosmic censorship conjecture. Axially symmetric black holes are the natural candidates to study these inequalities because the quasi-local angular momentum is well defined for them. We review recent results in this subject and we also describe the main ideas behind the proofs. Finally, a list of relevant open problems is presented. (topical review)
Design and Analysis of Symmetric Primitives
DEFF Research Database (Denmark)
Lauridsen, Martin Mehl
. In the second part, we delve into the matter of the various aspects of designing a symmetric cryptographic primitive. We start by considering generalizations of the widely acclaimed Advanced Encryption Standard (AES) block cipher. In particular, our focus is on a component operation in the cipher which permutes...... analyze and implement modes recommended by the National Institute of Standards and Technology (NIST), as well as authenticated encryption modes from the CAESAR competition, when instantiated with the AES. The data processed in our benchmarking has sizes representative to that of typical Internet traffic...... linear cryptanalysis. We apply this model to the standardized block cipher PRESENT. Finally, we present very generic attacks on two authenticated encryption schemes, AVALANCHE and RBS, by pointing out severe design flaws that can be leveraged to fully recover the secret key with very low complexity...
Cryptanalysis of Some Lightweight Symmetric Ciphers
DEFF Research Database (Denmark)
Abdelraheem, Mohamed Ahmed Awadelkareem Mohamed Ahmed
In recent years, the need for lightweight encryption systems has been increasing as many applications use RFID and sensor networks which have a very low computational power and thus incapable of performing standard cryptographic operations. In response to this problem, the cryptographic community...... on a variant of PRESENT with identical round keys. We propose a new attack named the Invariant Subspace Attack that was specifically mounted against the lightweight block cipher PRINTcipher. Furthermore, we mount several attacks on a recently proposed stream cipher called A2U2....... of the international standards in lightweight cryptography. This thesis aims at analyzing and evaluating the security of some the recently proposed lightweight symmetric ciphers with a focus on PRESENT-like ciphers, namely, the block cipher PRESENT and the block cipher PRINTcipher. We provide an approach to estimate...
Yokoi, Ryohei; Hayashi, Morimichi; Tamura, Toru; Kobayashi, Kazuo; Kuroda, Junji; Kusama, Hiroshi; Kagami, Hiroshi; Ono, Tamao
2008-12-01
Embryonic mortality and intrauterine growth retardation (IUGR) are induced by exposure of rodents to xenobiotic agents during the pregastrulation period of development. We examined the time course of the effects of methyl methanesulfonate (MMS), an alkylating agent, on conceptus development in order to clarify the relative roles of the embryo and the placenta in their induction. Pregnant rats were treated orally with a single dose of MMS (200 mg/kg) in the morning of gestation day (GD) 6 (peri-implantation stage). Embryonic mortality was increased on GD12 and thereafter by MMS treatment, with newly dead embryos showing placental hypoplasia at GD12. Embryo or fetal weight was also smaller for MMS-treated dams than for control dams from GD14 to GD20. The labyrinth zone and junctional zone (JZ) of the placenta were thinner in MMS-treated rats from GD12 to GD17 and from GD12 to GD20 (except for GD17), respectively. Furthermore, MMS-treated dams showed a smaller number of glycogen cells in the JZ on GD14. In contrast, the placental glycogen concentration was higher and the expression of glucose transporter 1 in the JZ remained at GD20. These results indicate that exposure of pregnant rats to MMS at the peri-implantation stage of embryogenesis affects placental development and growth. The placental impairment induced by MMS was likely responsible for the embryonic death observed 6 days after exposure of dams to this agent as well as for the IUGR of surviving embryos or fetuses throughout the gestation period.
Probabilistic cloning of three symmetric states
International Nuclear Information System (INIS)
Jimenez, O.; Bergou, J.; Delgado, A.
2010-01-01
We study the probabilistic cloning of three symmetric states. These states are defined by a single complex quantity, the inner product among them. We show that three different probabilistic cloning machines are necessary to optimally clone all possible families of three symmetric states. We also show that the optimal cloning probability of generating M copies out of one original can be cast as the quotient between the success probability of unambiguously discriminating one and M copies of symmetric states.
Classification of symmetric toroidal orbifolds
Energy Technology Data Exchange (ETDEWEB)
Fischer, Maximilian; Ratz, Michael; Torrado, Jesus [Technische Univ. Muenchen, Garching (Germany). Physik-Department; Vaudrevange, Patrick K.S. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2012-09-15
We provide a complete classification of six-dimensional symmetric toroidal orbifolds which yield N{>=}1 supersymmetry in 4D for the heterotic string. Our strategy is based on a classification of crystallographic space groups in six dimensions. We find in total 520 inequivalent toroidal orbifolds, 162 of them with Abelian point groups such as Z{sub 3}, Z{sub 4}, Z{sub 6}-I etc. and 358 with non-Abelian point groups such as S{sub 3}, D{sub 4}, A{sub 4} etc. We also briefly explore the properties of some orbifolds with Abelian point groups and N=1, i.e. specify the Hodge numbers and comment on the possible mechanisms (local or non-local) of gauge symmetry breaking.
Nonlinear PT-symmetric plaquettes
International Nuclear Information System (INIS)
Li Kai; Kevrekidis, P G; Malomed, Boris A; Günther, Uwe
2012-01-01
We introduce four basic two-dimensional (2D) plaquette configurations with onsite cubic nonlinearities, which may be used as building blocks for 2D PT-symmetric lattices. For each configuration, we develop a dynamical model and examine its PTsymmetry. The corresponding nonlinear modes are analyzed starting from the Hamiltonian limit, with zero value of the gain–loss coefficient, γ. Once the relevant waveforms have been identified (chiefly, in an analytical form), their stability is examined by means of linearization in the vicinity of stationary points. This reveals diverse and, occasionally, fairly complex bifurcations. The evolution of unstable modes is explored by means of direct simulations. In particular, stable localized modes are found in these systems, although the majority of identified solutions are unstable. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Quantum physics with non-Hermitian operators’. (paper)
Relativistic fluids in spherically symmetric space
International Nuclear Information System (INIS)
Dipankar, R.
1977-12-01
Some of McVittie and Wiltshire's (1977) solutions of Walker's (1935) isotropy conditions for relativistic perfect fluid spheres are generalized. Solutions are spherically symmetric and conformally flat
Symmetric splitting of very light systems
International Nuclear Information System (INIS)
Grotowski, K.; Majka, Z.; Planeta, R.
1985-01-01
Fission reactions that produce fragments close to one half the mass of the composite system are traditionally observed in heavy nuclei. In light systems, symmetric splitting is rarely observed and poorly understood. It would be interesting to verify the existence of the symmetric splitting of compound nuclei with A 12 C + 40 Ca, 141 MeV 9 Be + 40 Ca and 153 MeV 6 Li + 40 Ca. The out-of-plane correlation of symmetric products was also measured for the reaction 186 MeV 12 C + 40 Ca. The coincidence measurements of the 12 C + 40 Ca system demonstrated that essentially all of the inclusive yield of symmetric products around 40 0 results from a binary decay. To characterize the dependence of the symmetric splitting process on the excitation energy of the 12 C + 40 C system, inclusive measurements were made at bombarding energies of 74, 132, 162, and 185 MeV
Baryon symmetric big bang cosmology
Stecker, F. W.
1978-01-01
Both the quantum theory and Einsteins theory of special relativity lead to the supposition that matter and antimatter were produced in equal quantities during the big bang. It is noted that local matter/antimatter asymmetries may be reconciled with universal symmetry by assuming (1) a slight imbalance of matter over antimatter in the early universe, annihilation, and a subsequent remainder of matter; (2) localized regions of excess for one or the other type of matter as an initial condition; and (3) an extremely dense, high temperature state with zero net baryon number; i.e., matter/antimatter symmetry. Attention is given to the third assumption, which is the simplest and the most in keeping with current knowledge of the cosmos, especially as pertains the universality of 3 K background radiation. Mechanisms of galaxy formation are discussed, whereby matter and antimatter might have collided and annihilated each other, or have coexisted (and continue to coexist) at vast distances. It is pointed out that baryon symmetric big bang cosmology could probably be proved if an antinucleus could be detected in cosmic radiation.
Substring-Searchable Symmetric Encryption
Directory of Open Access Journals (Sweden)
Chase Melissa
2015-06-01
Full Text Available In this paper, we consider a setting where a client wants to outsource storage of a large amount of private data and then perform substring search queries on the data – given a data string s and a search string p, find all occurrences of p as a substring of s. First, we formalize an encryption paradigm that we call queryable encryption, which generalizes searchable symmetric encryption (SSE and structured encryption. Then, we construct a queryable encryption scheme for substring queries. Our construction uses suffix trees and achieves asymptotic efficiency comparable to that of unencrypted suffix trees. Encryption of a string of length n takes O(λn time and produces a ciphertext of size O(λn, and querying for a substring of length m that occurs k times takes O(λm+k time and three rounds of communication. Our security definition guarantees correctness of query results and privacy of data and queries against a malicious adversary. Following the line of work started by Curtmola et al. (ACM CCS 2006, in order to construct more efficient schemes we allow the query protocol to leak some limited information that is captured precisely in the definition. We prove security of our substring-searchable encryption scheme against malicious adversaries, where the query protocol leaks limited information about memory access patterns through the suffix tree of the encrypted string.
Beig, Robert; Siddiqui, Azad A.
2007-11-01
It is known that spherically symmetric static spacetimes admit a foliation by flat hypersurfaces. Such foliations have explicitly been constructed for some spacetimes, using different approaches, but none of them have proved or even discussed the uniqueness of these foliations. The issue of uniqueness becomes more important due to suitability of flat foliations for studying black hole physics. Here, flat spherically symmetric spacelike hypersurfaces are obtained by a direct method. It is found that spherically symmetric static spacetimes admit flat spherically symmetric hypersurfaces, and that these hypersurfaces are unique up to translation under the timelike Killing vector. This result guarantees the uniqueness of flat spherically symmetric foliations for such spacetimes.
The symmetric extendibility of quantum states
International Nuclear Information System (INIS)
Nowakowski, Marcin L
2016-01-01
Studies on the symmetric extendibility of quantum states have become particularly important in the context of the analysis of one-way quantum measures of entanglement, and the distillability and security of quantum protocols. In this paper we analyze composite systems containing a symmetric extendible part, with particular attention devoted to the one-way security of such systems. Further, we introduce a new one-way entanglement monotone based on the best symmetric approximation of a quantum state and the extendible number of a quantum state. We underpin these results with geometric observations about the structures of multi-party settings which posses substantial symmetric extendible components in their subspaces. The impossibility of reducing the maximal symmetric extendibility by means of the one-way local operations and classical communication method is pointed out on multiple copies. Finally, we state a conjecture linking symmetric extendibility with the one-way distillability and security of all quantum states, analyzing the behavior of a private key in the neighborhood of symmetric extendible states. (paper)
Averaging in spherically symmetric cosmology
International Nuclear Information System (INIS)
Coley, A. A.; Pelavas, N.
2007-01-01
The averaging problem in cosmology is of fundamental importance. When applied to study cosmological evolution, the theory of macroscopic gravity (MG) can be regarded as a long-distance modification of general relativity. In the MG approach to the averaging problem in cosmology, the Einstein field equations on cosmological scales are modified by appropriate gravitational correlation terms. We study the averaging problem within the class of spherically symmetric cosmological models. That is, we shall take the microscopic equations and effect the averaging procedure to determine the precise form of the correlation tensor in this case. In particular, by working in volume-preserving coordinates, we calculate the form of the correlation tensor under some reasonable assumptions on the form for the inhomogeneous gravitational field and matter distribution. We find that the correlation tensor in a Friedmann-Lemaitre-Robertson-Walker (FLRW) background must be of the form of a spatial curvature. Inhomogeneities and spatial averaging, through this spatial curvature correction term, can have a very significant dynamical effect on the dynamics of the Universe and cosmological observations; in particular, we discuss whether spatial averaging might lead to a more conservative explanation of the observed acceleration of the Universe (without the introduction of exotic dark matter fields). We also find that the correlation tensor for a non-FLRW background can be interpreted as the sum of a spatial curvature and an anisotropic fluid. This may lead to interesting effects of averaging on astrophysical scales. We also discuss the results of averaging an inhomogeneous Lemaitre-Tolman-Bondi solution as well as calculations of linear perturbations (that is, the backreaction) in an FLRW background, which support the main conclusions of the analysis
Linac design algorithm with symmetric segments
International Nuclear Information System (INIS)
Takeda, Harunori; Young, L.M.; Nath, S.; Billen, J.H.; Stovall, J.E.
1996-01-01
The cell lengths in linacs of traditional design are typically graded as a function of particle velocity. By making groups of cells and individual cells symmetric in both the CCDTL AND CCL, the cavity design as well as mechanical design and fabrication is simplified without compromising the performance. We have implemented a design algorithm in the PARMILA code in which cells and multi-cavity segments are made symmetric, significantly reducing the number of unique components. Using the symmetric algorithm, a sample linac design was generated and its performance compared with a similar one of conventional design
Symmetric charge transfer cross section of uranium
International Nuclear Information System (INIS)
Shibata, Takemasa; Ogura, Koichi
1995-03-01
Symmetric charge transfer cross section of uranium was calculated under consideration of reaction paths. In the charge transfer reaction a d 3/2 electron in the U atom transfers into the d-electron site of U + ( 4 I 9/2 ) ion. The J value of the U atom produced after the reaction is 6, 5, 4 or 3, at impact energy below several tens eV, only resonant charge transfer in which the product atom is ground state (J=6) takes place. Therefore, the cross section is very small (4-5 x 10 -15 cm 2 ) compared with that considered so far. In the energy range of 100-1000eV the cross section increases with the impact energy because near resonant charge transfer in which an s-electron in the U atom transfers into the d-electron site of U + ion. Charge transfer cross section between U + in the first excited state (289 cm -1 ) and U in the ground state was also obtained. (author)
Directory of Open Access Journals (Sweden)
Gurudutt S. Joshi
2017-10-01
Full Text Available A full term newborn small for gestational age Intra Uterine Growth Retardation (IUGR admitted with congenital dysmorphic features with icthyosis, atrichia, microcephaly and eye abnormalities, when explored further for other congenital malformations, revealed Corpus callosum hypoplasia and closely related features with two rare syndromes Icthyosis Follicularis Atrichia Photophobia (IFAP or Brain Anomalies Retardation, Ectodermal Dysplasia, Skeletal Deformities, Hirschsprung Disease, Hemivertebrae, Ear/Eye Anomalies, and Kidney Dysplasia (BRESHECK.
Symmetric nuclear matter with Skyrme interaction
International Nuclear Information System (INIS)
Manisa, K.; Bicer, A.; Atav, U.
2010-01-01
The equation of state (EOS) and some properties of symmetric nuclear matter, such as the saturation density, saturation energy and incompressibility, are obtained by using Skyrme's density-dependent effective nucleon-nucleon interaction.
Performance limitations of translationally symmetric nonimaging devices
Bortz, John C.; Shatz, Narkis E.; Winston, Roland
2001-11-01
The component of the optical direction vector along the symmetry axis is conserved for all rays propagated through a translationally symmetric optical device. This quality, referred to herein as the translational skew invariant, is analogous to the conventional skew invariant, which is conserved in rotationally symmetric optical systems. The invariance of both of these quantities is a consequence of Noether's theorem. We show how performance limits for translationally symmetric nonimaging optical devices can be derived from the distributions of the translational skew invariant for the optical source and for the target to which flux is to be transferred. Examples of computed performance limits are provided. In addition, we show that a numerically optimized non-tracking solar concentrator utilizing symmetry-breaking surface microstructure can overcome the performance limits associated with translational symmetry. The optimized design provides a 47.4% increase in efficiency and concentration relative to an ideal translationally symmetric concentrator.
Symmetrical parahiliar infiltrated, cough and dyspnoea
International Nuclear Information System (INIS)
Giraldo Estrada, Horacio; Escalante, Hector
2004-01-01
It is the case a patient to who is diagnosed symmetrical parahiliar infiltrated; initially she is diagnosed lymphoma Hodgkin, treaty with radiotherapy and chemotherapy, but the X rays of the thorax demonstrated parahiliars and paramediastinals infiltrated
Introduction to left-right symmetric models
International Nuclear Information System (INIS)
Grimus, W.
1993-01-01
We motivate left-right symmetric models by the possibility of spontaneous parity breaking. Then we describe the multiplets and the Lagrangian of such models. Finally we discuss lower bounds on the right-handed scale. (author)
A cosmological problem for maximally symmetric supergravity
International Nuclear Information System (INIS)
German, G.; Ross, G.G.
1986-01-01
Under very general considerations it is shown that inflationary models of the universe based on maximally symmetric supergravity with flat potentials are unable to resolve the cosmological energy density (Polonyi) problem. (orig.)
Theorem on axially symmetric gravitational vacuum configurations
Energy Technology Data Exchange (ETDEWEB)
Papadopoulos, A; Le Denmat, G [Paris-6 Univ., 75 (France). Inst. Henri Poincare
1977-01-24
A theorem is proved which asserts the non-existence of axially symmetric gravitational vacuum configurations with non-stationary rotation only. The eventual consequences in black-hole physics are suggested.
Symmetric Imidazolium-Based Paramagnetic Ionic Liquids
2017-11-29
Charts N/A Unclassified Unclassified Unclassified SAR 14 Kamran Ghiassi N/A 1 Symmetric Imidazolium-Based Paramagnetic Ionic Liquids Kevin T. Greeson...NUMBER (Include area code) 29 November 2017 Briefing Charts 01 November 2017 - 30 November 2017 Symmetric Imidazolium-Based Paramagnetic Ionic ... Liquids K. Greeson, K. Ghiassi, J. Alston, N. Redeker, J. Marcischak, L. Gilmore, A. Guenthner Air Force Research Laboratory (AFMC) AFRL/RQRP 9 Antares
The Symmetric Rudin-Shapiro Transform
DEFF Research Database (Denmark)
Harbo, Anders La-Cour
2003-01-01
A method for constructing spread spectrum sequences is presented. The method is based on a linear, orthogonal, and symmetric transform given as the Rudin-Shapiro transform (RST), which is in many respects quite similar to the Haar wavelet packet transform. The RST provides the means for generatin...... large sets of spread spectrum signals. This presentation provides a simple definition of the symmetric RST that leads to a fast N log(N) and numerically stable implementation of the transform....
The Symmetric Rudin-Shapiro Transform
DEFF Research Database (Denmark)
Harbo, Anders La-Cour
2003-01-01
A method for constructing spread spectrum sequences is presented. The method is based on a linear, orthogonal, symmetric transform, the Rudin-Shapiro transform (RST), which is in many respects quite similar to the Haar wavelet packet transform. The RST provides the means for generating large sets...... of spread spectrum signals. This presentation provides a simple definition of the symmetric RST that leads to a fast N log(N) and numerically stable implementation of the transform....
Pion condensation in symmetric nuclear matter
International Nuclear Information System (INIS)
Kabir, K.; Saha, S.; Nath, L.M.
1987-09-01
Using a model which is based essentially on the chiral SU(2)xSU(2) symmetry of the pion-nucleon interaction, we examine the possibility of pion condensation in symmetric nucleon matter. We find that the pion condensation is not likely to occur in symmetric nuclear matter for any finite value of the nuclear density. Consequently, no critical opalescence phenomenon is expected to be seen in the pion-nucleus interaction. (author). 20 refs
Pion condensation in symmetric nuclear matter
Kabir, K.; Saha, S.; Nath, L. M.
1988-01-01
Using a model which is based essentially on the chiral SU(2)×SU(2) symmetry of the pion-nucleon interaction, we examine the possibility of pion condensation in symmetric nucleon matter. We find that the pion condensation is not likely to occur in symmetric nuclear matter for any finite value of the nuclear density. Consequently, no critical opalescence phenomenom is expected to be seen in the pion-nucleus interaction.
Construction of symmetric Hadamard matrices of order 4v for v = 47, 73, 113
Directory of Open Access Journals (Sweden)
Balonin N. A.
2018-01-01
Full Text Available We continue our systematic search for symmetric Hadamard matrices based on the so called propus construction. In a previous paper this search covered the orders 4v with odd v ≤ 41. In this paper we cover the cases v = 43, 45, 47, 49, 51. The odd integers v < 120 for which no symmetric Hadamard matrices of order 4v are known are the following: 47, 59, 65, 67, 73, 81, 89, 93, 101, 103, 107, 109, 113, 119. By using the propus construction, we found several symmetric Hadamard matrices of order 4v for v = 47, 73, 113.
Comparison of eigensolvers for symmetric band matrices.
Moldaschl, Michael; Gansterer, Wilfried N
2014-09-15
We compare different algorithms for computing eigenvalues and eigenvectors of a symmetric band matrix across a wide range of synthetic test problems. Of particular interest is a comparison of state-of-the-art tridiagonalization-based methods as implemented in Lapack or Plasma on the one hand, and the block divide-and-conquer (BD&C) algorithm as well as the block twisted factorization (BTF) method on the other hand. The BD&C algorithm does not require tridiagonalization of the original band matrix at all, and the current version of the BTF method tridiagonalizes the original band matrix only for computing the eigenvalues. Avoiding the tridiagonalization process sidesteps the cost of backtransformation of the eigenvectors. Beyond that, we discovered another disadvantage of the backtransformation process for band matrices: In several scenarios, a lot of gradual underflow is observed in the (optional) accumulation of the transformation matrix and in the (obligatory) backtransformation step. According to the IEEE 754 standard for floating-point arithmetic, this implies many operations with subnormal (denormalized) numbers, which causes severe slowdowns compared to the other algorithms without backtransformation of the eigenvectors. We illustrate that in these cases the performance of existing methods from Lapack and Plasma reaches a competitive level only if subnormal numbers are disabled (and thus the IEEE standard is violated). Overall, our performance studies illustrate that if the problem size is large enough relative to the bandwidth, BD&C tends to achieve the highest performance of all methods if the spectrum to be computed is clustered. For test problems with well separated eigenvalues, the BTF method tends to become the fastest algorithm with growing problem size.
Crossing-symmetric solutions to low equations
International Nuclear Information System (INIS)
McLeod, R.J.; Ernst, D.J.
1985-01-01
Crossing symmetric models of the pion-nucleon interaction in which crossing symmetry is kept to lowest order in msub(π)/msub(N) are investigated. Two iterative techniques are developed to solve the crossing-symmetric Low equation. The techniques are used to solve the original Chew-Low equations and their generalizations to include the coupling to the pion-production channels. Small changes are found in comparison with earlier results which used an iterative technique proposed by Chew and Low and which did not produce crossing-symmetric results. The iterative technique of Chew and Low is shown to fail because of its inability to produce zeroes in the amplitude at complex energies while physical solutions to the model require such zeroes. We also prove that, within the class of solutions such that phase shifts approach zero for infinite energy, the solution to the Low equation is unique. (orig.)
Revisiting the Optical PT-Symmetric Dimer
Directory of Open Access Journals (Sweden)
José Delfino Huerta Morales
2016-08-01
Full Text Available Optics has proved a fertile ground for the experimental simulation of quantum mechanics. Most recently, optical realizations of PT -symmetric quantum mechanics have been shown, both theoretically and experimentally, opening the door to international efforts aiming at the design of practical optical devices exploiting this symmetry. Here, we focus on the optical PT -symmetric dimer, a two-waveguide coupler where the materials show symmetric effective gain and loss, and provide a review of the linear and nonlinear optical realizations from a symmetry-based point of view. We go beyond a simple review of the literature and show that the dimer is just the smallest of a class of planar N-waveguide couplers that are the optical realization of the Lorentz group in 2 + 1 dimensions. Furthermore, we provide a formulation to describe light propagation through waveguide couplers described by non-Hermitian mode coupling matrices based on a non-Hermitian generalization of the Ehrenfest theorem.
PT symmetric Aubry–Andre model
International Nuclear Information System (INIS)
Yuce, C.
2014-01-01
PT symmetric Aubry–Andre model describes an array of N coupled optical waveguides with position-dependent gain and loss. We show that the reality of the spectrum depends sensitively on the degree of quasi-periodicity for small number of lattice sites. We obtain the Hofstadter butterfly spectrum and discuss the existence of the phase transition from extended to localized states. We show that rapidly changing periodical gain/loss materials almost conserve the total intensity. - Highlights: • We show that PT symmetric Aubry–Andre model may have real spectrum. • We show that the reality of the spectrum depends sensitively on the degree of disorder. • We obtain the Hofstadter butterfly spectrum for PT symmetric Aubry–Andre model. • We discuss that phase transition from extended to localized states exists
PT symmetric Aubry–Andre model
Energy Technology Data Exchange (ETDEWEB)
Yuce, C., E-mail: cyuce@anadolu.edu.tr
2014-06-13
PT symmetric Aubry–Andre model describes an array of N coupled optical waveguides with position-dependent gain and loss. We show that the reality of the spectrum depends sensitively on the degree of quasi-periodicity for small number of lattice sites. We obtain the Hofstadter butterfly spectrum and discuss the existence of the phase transition from extended to localized states. We show that rapidly changing periodical gain/loss materials almost conserve the total intensity. - Highlights: • We show that PT symmetric Aubry–Andre model may have real spectrum. • We show that the reality of the spectrum depends sensitively on the degree of disorder. • We obtain the Hofstadter butterfly spectrum for PT symmetric Aubry–Andre model. • We discuss that phase transition from extended to localized states exists.
All-optical symmetric ternary logic gate
Chattopadhyay, Tanay
2010-09-01
Symmetric ternary number (radix=3) has three logical states (1¯, 0, 1). It is very much useful in carry free arithmetical operation. Beside this, the logical operation using this type of number system is also effective in high speed computation and communication in multi-valued logic. In this literature all-optical circuits for three basic symmetrical ternary logical operations (inversion, MIN and MAX) are proposed and described. Numerical simulation verifies the theoretical model. In this present scheme the different ternary logical states are represented by different polarized state of light. Terahertz optical asymmetric demultiplexer (TOAD) based interferometric switch has been used categorically in this manuscript.
Symmetry theorems via the continuous steiner symmetrization
Directory of Open Access Journals (Sweden)
L. Ragoub
2000-06-01
Full Text Available Using a new approach due to F. Brock called the Steiner symmetrization, we show first that if $u$ is a solution of an overdetermined problem in the divergence form satisfying the Neumann and non-constant Dirichlet boundary conditions, then $Omega$ is an N-ball. In addition, we show that we can relax the condition on the value of the Dirichlet boundary condition in the case of superharmonicity. Finally, we give an application to positive solutions of some semilinear elliptic problems in symmetric domains for the divergence case.
The Axially Symmetric One-Monopole
International Nuclear Information System (INIS)
Wong, K.-M.; Teh, Rosy
2009-01-01
We present new classical generalized one-monopole solution of the SU(2) Yang-Mills-Higgs theory with the Higgs field in the adjoint representation. We show that this solution with θ-winding number m = 1 and φ-winding number n = 1 is an axially symmetric generalization of the 't Hooft-Polyakov one-monopole. We construct this axially symmetric one-monopole solution by generalizing the large distance asymptotic solutions of the 't Hooft-Polyakov one-monopole to the Jacobi elliptic functions and solving the second order equations of motion numerically when the Higgs potential is vanishing. This solution is a non-BPS solution.
Symmetric splitting of very light systems
International Nuclear Information System (INIS)
Grotowski, K.; Majka, Z.; Planeta, R.
1984-01-01
Inclusive and coincidence measurements have been performed to study symmetric products from the reactions 74--186 MeV 12 C+ 40 Ca, 141 MeV 9 Be+ 40 Ca, and 153 MeV 6 Li+ 40 Ca. The binary decay of the composite system has been verified. Energy spectra, angular distributions, and fragment correlations are presented. The total kinetic energies for the symmetric products from these very light composite systems are compared to liquid drop model calculations and fission systematics
Symmetric low-voltage powering system for relativistic electronic devices
International Nuclear Information System (INIS)
Agafonov, A.V.; Lebedev, A.N.; Krastelev, E.G.
2005-01-01
A special driver for double-sided powering of relativistic magnetrons and several methods of localized electron flow forming in the interaction region of relativistic magnetrons are proposed and discussed. Two experimental installations are presented and discussed. One of them is designed for laboratory research and demonstration experiments at a rather low voltage. The other one is a prototype of a full-scale installation for an experimental research at relativistic levels of voltages on the microwave generation in the new integrated system consisting of a relativistic magnetron and symmetrical induction driver
Krein signature for instability of PT-symmetric states
Chernyavsky, Alexander; Pelinovsky, Dmitry E.
2018-05-01
Krein quantity is introduced for isolated neutrally stable eigenvalues associated with the stationary states in the PT-symmetric nonlinear Schrödinger equation. Krein quantity is real and nonzero for simple eigenvalues but it vanishes if two simple eigenvalues coalesce into a defective eigenvalue. A necessary condition for bifurcation of unstable eigenvalues from the defective eigenvalue is proved. This condition requires the two simple eigenvalues before the coalescence point to have opposite Krein signatures. The theory is illustrated with several numerical examples motivated by recent publications in physics literature.
All spherically symmetric charged anisotropic solutions for compact stars
Energy Technology Data Exchange (ETDEWEB)
Maurya, S.K. [University of Nizwa, Department of Mathematical and Physical Sciences, College of Arts and Science, Nizwa (Oman); Gupta, Y.K. [Raj Kumar Goel Institute of Technology, Department of Mathematics, Ghaziabad, UP (India); Ray, Saibal [Government College of Engineering and Ceramic Technology, Department of Physics, Kolkata, West Bengal (India)
2017-06-15
In the present paper we develop an algorithm for all spherically symmetric anisotropic charged fluid distributions. Considering a new source function ν(r) we find a set of solutions which is physically well behaved and represents compact stellar models. A detailed study specifically shows that the models actually correspond to strange stars in terms of their mass and radius. In this connection we investigate several physical properties like energy conditions, stability, mass-radius ratio, electric charge content, anisotropic nature and surface redshift through graphical plots and mathematical calculations. All the features from these studies are in excellent agreement with the already available evidence in theory as well as observations. (orig.)
Small diameter symmetric networks from linear groups
Campbell, Lowell; Carlsson, Gunnar E.; Dinneen, Michael J.; Faber, Vance; Fellows, Michael R.; Langston, Michael A.; Moore, James W.; Multihaupt, Andrew P.; Sexton, Harlan B.
1992-01-01
In this note is reported a collection of constructions of symmetric networks that provide the largest known values for the number of nodes that can be placed in a network of a given degree and diameter. Some of the constructions are in the range of current potential engineering significance. The constructions are Cayley graphs of linear groups obtained by experimental computation.
Sobolev spaces on bounded symmetric domains
Czech Academy of Sciences Publication Activity Database
Engliš, Miroslav
Roč. 60, č. 12 ( 2015 ), s. 1712-1726 ISSN 1747-6933 Institutional support: RVO:67985840 Keywords : bounded symmetric domain * Sobolev space * Bergman space Subject RIV: BA - General Mathematics Impact factor: 0.466, year: 2015 http://www.tandfonline.com/doi/abs/10.1080/17476933. 2015 .1043910
Cuspidal discrete series for semisimple symmetric spaces
DEFF Research Database (Denmark)
Andersen, Nils Byrial; Flensted-Jensen, Mogens; Schlichtkrull, Henrik
2012-01-01
We propose a notion of cusp forms on semisimple symmetric spaces. We then study the real hyperbolic spaces in detail, and show that there exists both cuspidal and non-cuspidal discrete series. In particular, we show that all the spherical discrete series are non-cuspidal. (C) 2012 Elsevier Inc. All...
Exact solutions of the spherically symmetric multidimensional ...
African Journals Online (AJOL)
The complete orthonormalised energy eigenfunctions and the energy eigenvalues of the spherically symmetric isotropic harmonic oscillator in N dimensions, are obtained through the methods of separation of variables. Also, the degeneracy of the energy levels are examined. KEY WORDS: - Schrödinger Equation, Isotropic ...
Super-symmetric informationally complete measurements
Energy Technology Data Exchange (ETDEWEB)
Zhu, Huangjun, E-mail: hzhu@pitp.ca
2015-11-15
Symmetric informationally complete measurements (SICs in short) are highly symmetric structures in the Hilbert space. They possess many nice properties which render them an ideal candidate for fiducial measurements. The symmetry of SICs is intimately connected with the geometry of the quantum state space and also has profound implications for foundational studies. Here we explore those SICs that are most symmetric according to a natural criterion and show that all of them are covariant with respect to the Heisenberg–Weyl groups, which are characterized by the discrete analog of the canonical commutation relation. Moreover, their symmetry groups are subgroups of the Clifford groups. In particular, we prove that the SIC in dimension 2, the Hesse SIC in dimension 3, and the set of Hoggar lines in dimension 8 are the only three SICs up to unitary equivalence whose symmetry groups act transitively on pairs of SIC projectors. Our work not only provides valuable insight about SICs, Heisenberg–Weyl groups, and Clifford groups, but also offers a new approach and perspective for studying many other discrete symmetric structures behind finite state quantum mechanics, such as mutually unbiased bases and discrete Wigner functions.
Harmonic maps of the bounded symmetric domains
International Nuclear Information System (INIS)
Xin, Y.L.
1994-06-01
A shrinking property of harmonic maps into R IV (2) is proved which is used to classify complete spacelike surfaces of the parallel mean curvature in R 4 2 with a reasonable condition on the Gauss image. Liouville-type theorems of harmonic maps from the higher dimensional bounded symmetric domains are also established. (author). 25 refs
On isotropic cylindrically symmetric stellar models
International Nuclear Information System (INIS)
Nolan, Brien C; Nolan, Louise V
2004-01-01
We attempt to match the most general cylindrically symmetric vacuum spacetime with a Robertson-Walker interior. The matching conditions show that the interior must be dust filled and that the boundary must be comoving. Further, we show that the vacuum region must be polarized. Imposing the condition that there are no trapped cylinders on an initial time slice, we can apply a result of Thorne's and show that trapped cylinders never evolve. This results in a simplified line element which we prove to be incompatible with the dust interior. This result demonstrates the impossibility of the existence of an isotropic cylindrically symmetric star (or even a star which has a cylindrically symmetric portion). We investigate the problem from a different perspective by looking at the expansion scalars of invariant null geodesic congruences and, applying to the cylindrical case, the result that the product of the signs of the expansion scalars must be continuous across the boundary. The result may also be understood in relation to recent results about the impossibility of the static axially symmetric analogue of the Einstein-Straus model
The Mathematics of Symmetrical Factorial Designs
Indian Academy of Sciences (India)
The Mathematics of Symmetrical Factorial Designs. Mausumi Bose (nee Sen) obtained her MSc degree in. Statistics from the Calcutta. University and PhD degree from the Indian Statistical. Institute. She is on the faculty of the Indian. Statistical Institute. Her main field of research interest is design and analysis of experiments.
Symmetric intersections of Rauzy fractals | Sellami | Quaestiones ...
African Journals Online (AJOL)
In this article we study symmetric subsets of Rauzy fractals of unimodular irreducible Pisot substitutions. The symmetry considered is re ection through the origin. Given an unimodular irreducible Pisot substitution, we consider the intersection of its Rauzy fractal with the Rauzy fractal of the reverse substitution. This set is ...
Fourier inversion on a reductive symmetric space
Ban, E.P. van den
1999-01-01
Let X be a semisimple symmetric space. In previous papers, [8] and [9], we have dened an explicit Fourier transform for X and shown that this transform is injective on the space C 1 c (X) ofcompactly supported smooth functions on X. In the present paper, which is a continuation of these papers, we
A viewpoint on nearly conformally symmetric manifold
International Nuclear Information System (INIS)
Rahman, M.S.
1990-06-01
Some observations, with definition, on Nearly Conformally Symmetric (NCS) manifold are made. A number of theorems concerning conformal change of metric and parallel tensors on NCS manifolds are presented. It is illustrated that a manifold M = R n-1 x R + 1 , endowed with a special metric, is NCS but not of harmonic curvature. (author). 8 refs
Harmonic analysis on reductive symmetric spaces
Ban, E.P. van den; Schlichtkrull, H.
2000-01-01
We give a relatively non-technical survey of some recent advances in the Fourier theory for semisimple symmetric spaces. There are three major results: An inversion formula for the Fourier transform, a Palley-Wiener theorem, which describes the Fourier image of the space of completely supported
Fourier transforms on a semisimple symmetric space
Ban, E.P. van den; Schlichtkrull, H.
1994-01-01
Let G=H be a semisimple symmetric space, that is, G is a connected semisimple real Lie group with an involution ?, and H is an open subgroup of the group of xed points for ? in G. The main purpose of this paper is to study an explicit Fourier transform on G=H. In terms of general representation
Fourier transforms on a semisimple symmetric space
Ban, E.P. van den; Carmona, J.; Delorme, P.
1997-01-01
Let G=H be a semisimple symmetric space, that is, G is a connected semisimple real Lie group with an involution ?, and H is an open subgroup of the group of xed points for ? in G. The main purpose of this paper is to study an explicit Fourier transform on G=H. In terms of general representation
Weakly Interacting Symmetric and Anti-Symmetric States in the Bilayer Systems
Marchewka, M.; Sheregii, E. M.; Tralle, I.; Tomaka, G.; Ploch, D.
We have studied the parallel magneto-transport in DQW-structures of two different potential shapes: quasi-rectangular and quasi-triangular. The quantum beats effect was observed in Shubnikov-de Haas (SdH) oscillations for both types of the DQW structures in perpendicular magnetic filed arrangement. We developed a special scheme for the Landau levels energies calculation by means of which we carried out the necessary simulations of beating effect. In order to obtain the agreement between our experimental data and the results of simulations, we introduced two different quasi-Fermi levels which characterize symmetric and anti-symmetric states in DQWs. The existence of two different quasi Fermi-Levels simply means, that one can treat two sub-systems (charge carriers characterized by symmetric and anti-symmetric wave functions) as weakly interacting and having their own rate of establishing the equilibrium state.
Representations of the infinite symmetric group
Borodin, Alexei
2016-01-01
Representation theory of big groups is an important and quickly developing part of modern mathematics, giving rise to a variety of important applications in probability and mathematical physics. This book provides the first concise and self-contained introduction to the theory on the simplest yet very nontrivial example of the infinite symmetric group, focusing on its deep connections to probability, mathematical physics, and algebraic combinatorics. Following a discussion of the classical Thoma's theorem which describes the characters of the infinite symmetric group, the authors describe explicit constructions of an important class of representations, including both the irreducible and generalized ones. Complete with detailed proofs, as well as numerous examples and exercises which help to summarize recent developments in the field, this book will enable graduates to enhance their understanding of the topic, while also aiding lecturers and researchers in related areas.
Symmetric, discrete fractional splines and Gabor systems
DEFF Research Database (Denmark)
Søndergaard, Peter Lempel
2006-01-01
In this paper we consider fractional splines as windows for Gabor frames. We introduce two new types of symmetric, fractional splines in addition to one found by Unser and Blu. For the finite, discrete case we present two families of splines: One is created by sampling and periodizing the continu......In this paper we consider fractional splines as windows for Gabor frames. We introduce two new types of symmetric, fractional splines in addition to one found by Unser and Blu. For the finite, discrete case we present two families of splines: One is created by sampling and periodizing...... the continuous splines, and one is a truly finite, discrete construction. We discuss the properties of these splines and their usefulness as windows for Gabor frames and Wilson bases....
Symmetric configurations highlighted by collective quantum coherence
Energy Technology Data Exchange (ETDEWEB)
Obster, Dennis [Radboud University, Institute for Mathematics, Astrophysics and Particle Physics, Nijmegen (Netherlands); Kyoto University, Yukawa Institute for Theoretical Physics, Kyoto (Japan); Sasakura, Naoki [Kyoto University, Yukawa Institute for Theoretical Physics, Kyoto (Japan)
2017-11-15
Recent developments in quantum gravity have shown the Lorentzian treatment to be a fruitful approach towards the emergence of macroscopic space-times. In this paper, we discuss another related aspect of the Lorentzian treatment: we argue that collective quantum coherence may provide a simple mechanism for highlighting symmetric configurations over generic non-symmetric ones. After presenting the general framework of the mechanism, we show the phenomenon in some concrete simple examples in the randomly connected tensor network, which is tightly related to a certain model of quantum gravity, i.e., the canonical tensor model. We find large peaks at configurations invariant under Lie-group symmetries as well as a preference for charge quantization, even in the Abelian case. In future study, this simple mechanism may provide a way to analyze the emergence of macroscopic space-times with global symmetries as well as various other symmetries existing in nature, which are usually postulated. (orig.)
Overlap-free symmetric D 0 Lwords
Directory of Open Access Journals (Sweden)
Anna Frid
2001-12-01
Full Text Available A D0L word on an alphabet Σ={0,1,…,q-1} is called symmetric if it is a fixed point w=φ(w of a morphism φ:Σ * → Σ * defined by φ(i= t 1 + i t 2 + i … t m + i for some word t 1 t 2 … t m (equal to φ(0 and every i ∈ Σ; here a means a mod q. We prove a result conjectured by J. Shallit: if all the symbols in φ(0 are distinct (i.e., if t i ≠ t j for i ≠ j, then the symmetric D0L word w is overlap-free, i.e., contains no factor of the form axaxa for any x ∈ Σ * and a ∈ Σ.
Young—Capelli symmetrizers in superalgebras†
Brini, Andrea; Teolis, Antonio G. B.
1989-01-01
Let Supern[U [unk] V] be the nth homogeneous subspace of the supersymmetric algebra of U [unk] V, where U and V are Z2-graded vector spaces over a field K of characteristic zero. The actions of the general linear Lie superalgebras pl(U) and pl(V) span two finite-dimensional K-subalgebras B and [unk] of EndK(Supern[U [unk] V]) that are the centralizers of each other. Young—Capelli symmetrizers and Young—Capelli *-symmetrizers give rise to K-linear bases of B and [unk] containing orthogonal systems of idempotents; thus they yield complete decompositions of B and [unk] into minimal left and right ideals, respectively. PMID:16594014
Commutative curvature operators over four-dimensional generalized symmetric
Directory of Open Access Journals (Sweden)
Ali Haji-Badali
2014-12-01
Full Text Available Commutative properties of four-dimensional generalized symmetric pseudo-Riemannian manifolds were considered. Specially, in this paper, we studied Skew-Tsankov and Jacobi-Tsankov conditions in 4-dimensional pseudo-Riemannian generalized symmetric manifolds.
Irreducible complexity of iterated symmetric bimodal maps
Directory of Open Access Journals (Sweden)
J. P. Lampreia
2005-01-01
Full Text Available We introduce a tree structure for the iterates of symmetric bimodal maps and identify a subset which we prove to be isomorphic to the family of unimodal maps. This subset is used as a second factor for a ∗-product that we define in the space of bimodal kneading sequences. Finally, we give some properties for this product and study the ∗-product induced on the associated Markov shifts.
A symmetric Roos bound for linear codes
Duursma, I.M.; Pellikaan, G.R.
2006-01-01
The van Lint–Wilson AB-method yields a short proof of the Roos bound for the minimum distance of a cyclic code. We use the AB-method to obtain a different bound for the weights of a linear code. In contrast to the Roos bound, the role of the codes A and B in our bound is symmetric. We use the bound
Symmetric voltage-controlled variable resistance
Vanelli, J. C.
1978-01-01
Feedback network makes resistance of field-effect transistor (FET) same for current flowing in either direction. It combines control voltage with source and load voltages to give symmetric current/voltage characteristics. Since circuit produces same magnitude output voltage for current flowing in either direction, it introduces no offset in presense of altering polarity signals. It is therefore ideal for sensor and effector circuits in servocontrol systems.
Resistor Networks based on Symmetrical Polytopes
Directory of Open Access Journals (Sweden)
Jeremy Moody
2015-03-01
Full Text Available This paper shows how a method developed by Van Steenwijk can be generalized to calculate the resistance between any two vertices of a symmetrical polytope all of whose edges are identical resistors. The method is applied to a number of cases that have not been studied earlier such as the Archimedean polyhedra and their duals in three dimensions, the regular polytopes in four dimensions and the hypercube in any number of dimensions.
Symmetric scrolled packings of multilayered carbon nanoribbons
Savin, A. V.; Korznikova, E. A.; Lobzenko, I. P.; Baimova, Yu. A.; Dmitriev, S. V.
2016-06-01
Scrolled packings of single-layer and multilayer graphene can be used for the creation of supercapacitors, nanopumps, nanofilters, and other nanodevices. The full atomistic simulation of graphene scrolls is restricted to consideration of relatively small systems in small time intervals. To overcome this difficulty, a two-dimensional chain model making possible an efficient calculation of static and dynamic characteristics of nanoribbon scrolls with allowance for the longitudinal and bending stiffness of nanoribbons is proposed. The model is extended to the case of scrolls of multilayer graphene. Possible equilibrium states of symmetric scrolls of multilayer carbon nanotribbons rolled up so that all nanoribbons in the scroll are equivalent are found. Dependences of the number of coils, the inner and outer radii, lowest vibrational eigenfrequencies of rolled packages on the length L of nanoribbons are obtained. It is shown that the lowest vibrational eigenfrequency of a symmetric scroll decreases with a nanoribbon length proportionally to L -1. It is energetically unfavorable for too short nanoribbons to roll up, and their ground state is a stack of plane nanoribbons. With an increasing number k of layers, the nanoribbon length L necessary for creation of symmetric scrolls increases. For a sufficiently small number of layers k and a sufficiently large nanoribbon length L, the scrolled packing has the lowest energy as compared to that of stack of plane nanoribbons and folded structures. The results can be used for development of nanomaterials and nanodevices on the basis of graphene scrolled packings.
Is the Universe matter-antimatter symmetric
International Nuclear Information System (INIS)
Alfven, H.
1976-09-01
According to the symmetric cosmology there should be antimatter regions in space which are equally as large as the matter regions. The regions of different kind are separated by Leidenfrost layers, which may be very thin and not observable from a distance. This view has met resistance which in part is based on the old view that the dilute interstellar and intergalactic medium is more or less homogeneous. However, through space research in the magnetosphere and interplanetary space we know that thin layers, dividing space into regions of different magnetisation, exist and based on this it is concluded that space in general has a cellular structure. This result may break down the psychological resistance to the symmetric theory. The possibility that every second star in our galaxy consists of antimatter is discussed, and it is shown that this view is not in conflict with any observations. As most stars are likely to be surrounded by solar systems of a structure like our own, it is concluded that collisions between comets and antistars (or anticomets and stars) would be rather frequent. Such collisions would result in phenomena of the same type as the observed cosmic γ-ray bursts. Another support for the symmetric cosmology is the continuous X-ray background radiation. Also many of the observed large energy releases in cosmos are likely to be due to annihilation
On the harmonic starlike functions with respect to symmetric ...
African Journals Online (AJOL)
In the present paper, we introduce the notions of functions harmonic starlike with respect to symmetric, conjugate and symmetric conjugate points. Such results as coefficient inequalities and structural formulae for these function classes are proved. Keywords: Harmonic functions, harmonic starlike functions, symmetric points, ...
Dual formulation of covariant nonlinear duality-symmetric action of kappa-symmetric D3-brane
Vanichchapongjaroen, Pichet
2018-02-01
We study the construction of covariant nonlinear duality-symmetric actions in dual formulation. Essentially, the construction is the PST-covariantisation and nonlinearisation of Zwanziger action. The covariantisation made use of three auxiliary scalar fields. Apart from these, the construction proceed in a similar way to that of the standard formulation. For example, the theories can be extended to include interactions with external fields, and that the theories possess two local PST symmetries. We then explicitly demonstrate the construction of covariant nonlinear duality-symmetric actions in dual formulation of DBI theory, and D3-brane. For each of these theories, the twisted selfduality condition obtained from duality-symmetric actions are explicitly shown to match with the duality relation between field strength and its dual from the one-potential actions. Their on-shell actions between the duality-symmetric and the one-potential versions are also shown to match. We also explicitly prove kappa-symmetry of the covariant nonlinear duality-symmetric D3-brane action in dual formulation.
Email authentication using symmetric and asymmetric key algorithm encryption
Halim, Mohamad Azhar Abdul; Wen, Chuah Chai; Rahmi, Isredza; Abdullah, Nurul Azma; Rahman, Nurul Hidayah Ab.
2017-10-01
Protection of sensitive or classified data from unauthorized access, hackers and other personals is virtue. Storage of data is done in devices such as USB, external hard disk, laptops, I-Pad or at cloud. Cloud computing presents with both ups and downs. However, storing information elsewhere increases risk of being attacked by hackers. Besides, the risk of losing the device or being stolen is increased in case of storage in portable devices. There are array of mediums of communications and even emails used to send data or information but these technologies come along with severe weaknesses such as absence of confidentiality where the message sent can be altered and sent to the recipient. No proofs are shown to the recipient that the message received is altered. The recipient would not find out unless he or she checks with the sender. Without encrypted of data or message, sniffing tools and software can be used to hack and read the information since it is in plaintext. Therefore, an electronic mail authentication is proposed, namely Hybrid Encryption System (HES). The security of HES is protected using asymmetric and symmetric key algorithms. The asymmetric algorithm is RSA and symmetric algorithm is Advance Encryption Standard. With the combination for both algorithms in the HES may provide the confidentiality and authenticity to the electronic documents send from the sender to the recipient. In a nutshell, the HES will help users to protect their valuable documentation and data from illegal third party user.
A computer controlled ultrasonic measurement and testequipment for rotation-symmetrical products
International Nuclear Information System (INIS)
Abend, K.; Lang, R.; Schmidt, U.; Schuett, U.; Sterberg, W.
1976-01-01
During production of rotation-symmetrical thin wall precision tubes, dimensions must be measured and the tubes have to be inspected for surface defects. Within the production area of the tubes, several measurement points for different applications are located at different places. The paper describes their on-line connection to a process-computer system
Conditions for Effective Application of Analysis of Symmetrically-Predicted Endogenous Subgroups
Peck, Laura R.
2015-01-01
Several analytic strategies exist for opening up the "black box" to reveal more about what drives policy and program impacts. This article focuses on one of these strategies: the Analysis of Symmetrically-Predicted Endogenous Subgroups (ASPES). ASPES uses exogenous baseline data to identify endogenously-defined subgroups, keeping the…
Spherically symmetric self-similar universe
Energy Technology Data Exchange (ETDEWEB)
Dyer, C C [Toronto Univ., Ontario (Canada)
1979-10-01
A spherically symmetric self-similar dust-filled universe is considered as a simple model of a hierarchical universe. Observable differences between the model in parabolic expansion and the corresponding homogeneous Einstein-de Sitter model are considered in detail. It is found that an observer at the centre of the distribution has a maximum observable redshift and can in principle see arbitrarily large blueshifts. It is found to yield an observed density-distance law different from that suggested by the observations of de Vaucouleurs. The use of these solutions as central objects for Swiss-cheese vacuoles is discussed.
Dijet rates with symmetric Et cuts
International Nuclear Information System (INIS)
Banfi, Andrea; Dasgupta, Mrinal
2004-01-01
We consider dijet production in the region where symmetric cuts on the transverse energy, E t , are applied to the jets. In this region next-to-leading order calculations are unreliable and an all-order resummation of soft gluon effects is needed, which we carry out. Although, for illustrative purposes, we choose dijets produced in deep inelastic scattering, our general ideas apply additionally to dijets produced in photoproduction or gamma-gamma processes and should be relevant also to the study of prompt di-photon E t spectra in association with a recoiling jet, in hadron-hadron processes. (author)
Covariant, chirally symmetric, confining model of mesons
International Nuclear Information System (INIS)
Gross, F.; Milana, J.
1991-01-01
We introduce a new model of mesons as quark-antiquark bound states. The model is covariant, confining, and chirally symmetric. Our equations give an analytic solution for a zero-mass pseudoscalar bound state in the case of exact chiral symmetry, and also reduce to the familiar, highly successful nonrelativistic linear potential models in the limit of heavy-quark mass and lightly bound systems. In this fashion we are constructing a unified description of all the mesons from the π through the Υ. Numerical solutions for other cases are also presented
Symmetric Logic Synthesis with Phase Assignment
Benschop, N. F.
2001-01-01
Decomposition of any Boolean Function BF_n of n binary inputs into an optimal inverter coupled network of Symmetric Boolean functions SF_k (k \\leq n) is described. Each SF component is implemented by Threshold Logic Cells, forming a complete and compact T-Cell Library. Optimal phase assignment of input polarities maximizes local symmetries. The "rank spectrum" is a new BF_n description independent of input ordering, obtained by mapping its minterms onto an othogonal n \\times n grid of (transi...
Elastic energy for reflection-symmetric topologies
International Nuclear Information System (INIS)
Majumdar, A; Robbins, J M; Zyskin, M
2006-01-01
Nematic liquid crystals in a polyhedral domain, a prototype for bistable displays, may be described by a unit-vector field subject to tangent boundary conditions. Here we consider the case of a rectangular prism. For configurations with reflection-symmetric topologies, we derive a new lower bound for the one-constant elastic energy. For certain topologies, called conformal and anticonformal, the lower bound agrees with a previous result. For the remaining topologies, called nonconformal, the new bound is an improvement. For nonconformal topologies we derive an upper bound, which differs from the lower bound by a factor depending only on the aspect ratios of the prism
Nanotribology of Symmetric and Asymmetric Liquid Lubricants
Directory of Open Access Journals (Sweden)
Shinji Yamada
2010-03-01
Full Text Available When liquid molecules are confined in a narrow gap between smooth surfaces, their dynamic properties are completely different from those of the bulk. The molecular motions are highly restricted and the system exhibits solid-like responses when sheared slowly. This solidification behavior is very dependent on the molecular geometry (shape of liquids because the solidification is induced by the packing of molecules into ordered structures in confinement. This paper reviews the measurements of confined structures and friction of symmetric and asymmetric liquid lubricants using the surface forces apparatus. The results show subtle and complex friction mechanisms at the molecular scale.
Unary self-verifying symmetric difference automata
CSIR Research Space (South Africa)
Marais, Laurette
2016-07-01
Full Text Available stream_source_info Marais_2016_ABSTRACT.pdf.txt stream_content_type text/plain stream_size 796 Content-Encoding ISO-8859-1 stream_name Marais_2016_ABSTRACT.pdf.txt Content-Type text/plain; charset=ISO-8859-1 18th... International Workshop on Descriptional Complexity of Formal Systems, 5 - 8 July 2016, Bucharest, Romania Unary self-verifying symmetric difference automata Laurette Marais1,2 and Lynette van Zijl1(B) 1 Department of Computer Science, Stellenbosch...
Characterisation of an AGATA symmetric prototype detector
International Nuclear Information System (INIS)
Nelson, L.; Dimmock, M.R.; Boston, A.J.; Boston, H.C.; Cresswell, J.R.; Nolan, P.J.; Lazarus, I.; Simpson, J.; Medina, P.; Santos, C.; Parisel, C.
2007-01-01
The Advanced GAmma Tracking Array (AGATA) symmetric prototype detector has been tested at University of Liverpool. A 137 Ce source, collimated to a 2 mm diameter, was scanned across the front face of the detector and data were acquired utilising digital electronics. Pulse shapes from a selection of well-defined photon interaction positions have been analysed to investigate the position sensitivity of the detector. Furthermore, the application of the electric field simulation software, Multi Geometry Simulation (MGS) to generate theoretical pulse shapes for AGATA detectors has been presented
How Symmetrical Assumptions Advance Strategic Management Research
DEFF Research Database (Denmark)
Foss, Nicolai Juul; Hallberg, Hallberg
2014-01-01
We develop the case for symmetrical assumptions in strategic management theory. Assumptional symmetry obtains when assumptions made about certain actors and their interactions in one of the application domains of a theory are also made about this set of actors and their interactions in other...... application domains of the theory. We argue that assumptional symmetry leads to theoretical advancement by promoting the development of theory with greater falsifiability and stronger ontological grounding. Thus, strategic management theory may be advanced by systematically searching for asymmetrical...
Characterisation of an AGATA symmetric prototype detector
Energy Technology Data Exchange (ETDEWEB)
Nelson, L. [Oliver Lodge Laboratory, University of Liverpool, Oxford Street, Liverpool L69 7ZE (United Kingdom)]. E-mail: ln@ns.ph.liv.ac.uk; Dimmock, M.R. [Oliver Lodge Laboratory, University of Liverpool, Oxford Street, Liverpool L69 7ZE (United Kingdom)]. E-mail: mrd@ns.ph.liv.ac.uk; Boston, A.J. [Oliver Lodge Laboratory, University of Liverpool, Oxford Street, Liverpool L69 7ZE (United Kingdom)]. E-mail: ajb@ns.ph.liv.ac.uk; Boston, H.C. [Oliver Lodge Laboratory, University of Liverpool, Oxford Street, Liverpool L69 7ZE (United Kingdom); Cresswell, J.R. [Oliver Lodge Laboratory, University of Liverpool, Oxford Street, Liverpool L69 7ZE (United Kingdom); Nolan, P.J. [Oliver Lodge Laboratory, University of Liverpool, Oxford Street, Liverpool L69 7ZE (United Kingdom); Lazarus, I. [CCLRC Daresbury Laboratory, Daresbury, Warrington WA4 4AD (United Kingdom); Simpson, J. [CCLRC Daresbury Laboratory, Daresbury, Warrington WA4 4AD (United Kingdom); Medina, P. [Institut de Recherches Subatomiques, Strasbourg BP28 67037 (France); Santos, C. [Institut de Recherches Subatomiques, Strasbourg BP28 67037 (France); Parisel, C. [Institut de Recherches Subatomiques, Strasbourg BP28 67037 (France)
2007-04-01
The Advanced GAmma Tracking Array (AGATA) symmetric prototype detector has been tested at University of Liverpool. A {sup 137}Ce source, collimated to a 2 mm diameter, was scanned across the front face of the detector and data were acquired utilising digital electronics. Pulse shapes from a selection of well-defined photon interaction positions have been analysed to investigate the position sensitivity of the detector. Furthermore, the application of the electric field simulation software, Multi Geometry Simulation (MGS) to generate theoretical pulse shapes for AGATA detectors has been presented.
Soft theorems for shift-symmetric cosmologies
Finelli, Bernardo; Goon, Garrett; Pajer, Enrico; Santoni, Luca
2018-03-01
We derive soft theorems for single-clock cosmologies that enjoy a shift symmetry. These so-called consistency conditions arise from a combination of a large diffeomorphism and the internal shift symmetry and fix the squeezed limit of all correlators with a soft scalar mode. As an application, we show that our results reproduce the squeezed bispectrum for ultra-slow-roll inflation, a particular shift-symmetric, nonattractor model which is known to violate Maldacena's consistency relation. Similar results have been previously obtained by Mooij and Palma using background-wave methods. Our results shed new light on the infrared structure of single-clock cosmological spacetimes.
Pion condensation in symmetric nuclear matter
International Nuclear Information System (INIS)
Shamsunnahar, T.; Saha, S.; Kabir, K.; Nath, L.M.
1991-01-01
We have investigated the possibility of pion condensation in symmetric nuclear matter using a model of pion-nucleon interaction based essentially on chiral SU(2) x SU(2) symmetry. We have found that pion condensation is not possible for any finite value of the density. Consequently, no critical opalescence phenomenon is likely to be seen in pion-nucleus scattering nor is it likely to be possible to explain the EMC effect in terms of an increased number of pions in the nucleus. (author)
Baryon symmetric big-bang cosmology
Energy Technology Data Exchange (ETDEWEB)
Stecker, F.W.
1978-04-01
The framework of baryon-symmetric big-bang cosmology offers the greatest potential for deducing the evolution of the universe as a consequence of physical laws and processes with the minimum number of arbitrary assumptions as to initial conditions in the big-bang. In addition, it offers the possibility of explaining the photon-baryon ratio in the universe and how galaxies and galaxy clusters are formed, and also provides the only acceptable explanation at present for the origin of the cosmic gamma ray background radiation.
Baryon symmetric big-bang cosmology
International Nuclear Information System (INIS)
Stecker, F.W.
1978-04-01
The framework of baryon-symmetric big-bang cosmology offers the greatest potential for deducing the evolution of the universe as a consequence of physical laws and processes with the minimum number of arbitrary assumptions as to initial conditions in the big-bang. In addition, it offers the possibility of explaining the photon-baryon ratio in the universe and how galaxies and galaxy clusters are formed, and also provides the only acceptable explanation at present for the origin of the cosmic gamma ray background radiation
Geometrodynamics of spherically symmetric Lovelock gravity
International Nuclear Information System (INIS)
Kunstatter, Gabor; Taves, Tim; Maeda, Hideki
2012-01-01
We derive the Hamiltonian for spherically symmetric Lovelock gravity using the geometrodynamics approach pioneered by Kuchar (1994 Phys. Rev. D 50 3961) in the context of four-dimensional general relativity. When written in terms of the areal radius, the generalized Misner-Sharp mass and their conjugate momenta, the generic Lovelock action and Hamiltonian take on precisely the same simple forms as in general relativity. This result supports the interpretation of Lovelock gravity as the natural higher dimensional extension of general relativity. It also provides an important first step towards the study of the quantum mechanics, Hamiltonian thermodynamics and formation of generic Lovelock black holes. (fast track communication)
Wu, Jiaye; Yang, Xiangbo
2017-10-30
In this paper, we construct a 1D PT-symmetric Thue-Morse aperiodic optical waveguide network (PTSTMAOWN) and mainly investigate the ultrastrong extraordinary transmission and reflection. We propose an approach to study the photonic modes and solve the problem of calculating photonic modes distributions in aperiodic networks due to the lack of dispersion functions and find that in a PTSTMAOWN there exist more photonic modes and more spontaneous PT-symmetric breaking points, which are quite different from other reported PT-symmetric optical systems. Additionally, we develop a method to sort spontaneous PT-symmetric breaking point zones to seek the strongest extraordinary point and obtain that at this point the strongest extraordinary transmission and reflection arrive at 2.96316 × 10 5 and 1.32761 × 10 5 , respectively, due to the PT-symmetric coupling resonance and the special symmetry pattern of TM networks. These enormous gains are several orders of magnitude larger than the previous results. This optical system may possess potential in designing optical amplifier, optical logic elements in photon computers and ultrasensitive optical switches with ultrahigh monochromatity.
International Nuclear Information System (INIS)
Martin Sanchez, A.; Vera Tome, F.; Caceres Marzal, D.; Bland, C.J.
1994-01-01
A pulse-height spectrum of alpha-particle emissions at discrete energies can be fitted by the peak-shape functions generated by combining asymmetric truncated exponential functions with a symmetric Gaussian distribution. These functions have been applied successfully by several workers. A correlation was previously found between the variance of the symmetric Gaussian portion of the fitting function, and the parameter characterising the principal exponential tailing function. The results of a more detailed experimental study are reported, which involve varying the angle and the distance between the source and the detector. This analysis shows that the parameters of the symmetric and asymmetric parts of the fitted functions seem to depend on either the detector or the source. These parameters are influenced by the energy loss suffered by the alpha-particles as well as by the efficiency of charge collection in the solid-state detector. (orig.)
Conjugate gradient type methods for linear systems with complex symmetric coefficient matrices
Freund, Roland
1989-01-01
We consider conjugate gradient type methods for the solution of large sparse linear system Ax equals b with complex symmetric coefficient matrices A equals A(T). Such linear systems arise in important applications, such as the numerical solution of the complex Helmholtz equation. Furthermore, most complex non-Hermitian linear systems which occur in practice are actually complex symmetric. We investigate conjugate gradient type iterations which are based on a variant of the nonsymmetric Lanczos algorithm for complex symmetric matrices. We propose a new approach with iterates defined by a quasi-minimal residual property. The resulting algorithm presents several advantages over the standard biconjugate gradient method. We also include some remarks on the obvious approach to general complex linear systems by solving equivalent real linear systems for the real and imaginary parts of x. Finally, numerical experiments for linear systems arising from the complex Helmholtz equation are reported.
Electroweak Baryogenesis in R-symmetric Supersymmetry
Energy Technology Data Exchange (ETDEWEB)
Fok, R.; Kribs, Graham D.; Martin, Adam; Tsai, Yuhsin
2013-03-01
We demonstrate that electroweak baryogenesis can occur in a supersymmetric model with an exact R-symmetry. The minimal R-symmetric supersymmetric model contains chiral superfields in the adjoint representation, giving Dirac gaugino masses, and an additional set of "R-partner" Higgs superfields, giving R-symmetric \\mu-terms. New superpotential couplings between the adjoints and the Higgs fields can simultaneously increase the strength of the electroweak phase transition and provide additional tree-level contributions to the lightest Higgs mass. Notably, no light stop is present in this framework, and in fact, we require both stops to be above a few TeV to provide sufficient radiative corrections to the lightest Higgs mass to bring it up to 125 GeV. Large CP-violating phases in the gaugino/higgsino sector allow us to match the baryon asymmetry of the Universe with no constraints from electric dipole moments due to R-symmetry. We briefly discuss some of the more interesting phenomenology, particularly of the of the lightest CP-odd scalar.
Calculating the C operator in PT-symmetric quantum mechanics
International Nuclear Information System (INIS)
Bender, C.M.
2004-01-01
It has recently been shown that a non-Hermitian Hamiltonian H possessing an unbroken PT-symmetry (i) has a real spectrum that is bounded below, and (ii) defines a unitary theory of quantum mechanics with positive norm. The proof of unitarity requires a linear operator C, which was originally defined as a sum over the eigenfunctions of H. However, using this definition it is cumbersome to calculate C in quantum mechanics and impossible in quantum field theory. An alternative method is devised here for calculating C directly in terms of the operator dynamical variables of the quantum theory. This new method is general and applies to a variety of quantum mechanical systems having several degrees of freedom. More importantly, this method can be used to calculate the C operator in quantum field theory. The C operator is a new time-independent observable in PT-symmetric quantum field theory. (author)
Using a commercial symmetric multiprocessor for lattice QCD
International Nuclear Information System (INIS)
Brower, R.C.; Chen, D.; Negele, J.W.
1998-01-01
In its evolution, the computer industry has reached the point when considerable computing power can be packaged on a single microprocessor chip. At the same time, costs of designing a computer system around such a CPU are growing. For these reasons we decided to explore a possibility of using commercially available symmetric multiprocessors (SMP) as building blocks for the LQCD computer. Careful analysis of the architecture allowed us to build a QCD primitive library running close to the peak performance on the UltraSPARC processor. As a result, multithreaded QCD code (both the heatbath and the Wilson fermion inverter) runs at about 50% efficiency on a single SMP. The communication between different CPUs is handled by a coherent memory system. Currently we are planning to connect several SMPs with a high bandwidth network into a single system. (orig.)
A symmetric geometric measure and the dynamics of quantum discord
International Nuclear Information System (INIS)
Jiang Feng-Jian; Shi Ming-Jun; Lü Hai-Jiang; Yan Xin-Hu
2013-01-01
A symmetric measure of quantum correlation based on the Hilbert—Schmidt distance is presented in this paper. For two-qubit states, we considerably simplify the optimization procedure so that numerical evaluation can be performed efficiently. Analytical expressions for the quantum correlation are attained for some special states. We further investigate the dynamics of quantum correlation of the system qubits in the presence of independent dissipative environments. Several nontrivial aspects are demonstrated. We find that the quantum correlation can increase even if the system state is suffering from dissipative noise. Sudden changes occur, even twice, in the time evolution of quantum correlation. There exists a certain correspondence between the evolution of quantum correlation in the systems and that in the environments, and the quantum correlation in the systems will be transferred into the environments completely and asymptotically. (general)
Rings of continuous functions, symmetric products, and Frobenius algebras
International Nuclear Information System (INIS)
Buchstaber, Viktor M; Rees, E G
2004-01-01
A constructive proof is given for the classical theorem of Gel'fand and Kolmogorov (1939) characterising the image of the evaluation map from a compact Hausdorff space X into the linear space C(X)* dual to the ring C(X) of continuous functions on X. Our approach to the proof enabled us to obtain a more general result characterising the image of the evaluation map from the symmetric products Sym n (X) into C(X)*. A similar result holds if X=C m and leads to explicit equations for symmetric products of affine algebraic varieties as algebraic subvarieties in the linear space dual to the polynomial ring. This leads to a better understanding of the algebra of multisymmetric polynomials. The proof of all these results is based on a formula used by Frobenius in 1896 in defining higher characters of finite groups. This formula had no further applications for a long time; however, it has appeared in several independent contexts during the last fifteen years. It was used by A. Wiles and R.L. Taylor in studying representations and by H.-J. Hoehnke and K.W. Johnson and later by J. McKay in studying finite groups. It plays an important role in our work concerning multivalued groups. Several properties of this remarkable formula are described. It is also used to prove a theorem on the structure constants of Frobenius algebras, which have recently attracted attention due to constructions taken from topological field theory and singularity theory. This theorem develops a result of Hoehnke published in 1958. As a corollary, a direct self-contained proof is obtained for the fact that the 1-, 2-, and 3-characters of the regular representation determine a finite group up to isomorphism. This result was first published by Hoehnke and Johnson in 1992
A symmetric bipolar nebula around MWC 922.
Tuthill, P G; Lloyd, J P
2007-04-13
We report regular and symmetric structure around dust-enshrouded Be star MWC 922 obtained with infrared imaging. Biconical lobes that appear nearly square in aspect, forming this "Red Square" nebula, are crossed by a series of rungs that terminate in bright knots or "vortices," and an equatorial dark band crossing the core delimits twin hyperbolic arcs. The intricate yet cleanly constructed forms that comprise the skeleton of the object argue for minimal perturbation from global turbulent or chaotic effects. We also report the presence of a linear comb structure, which may arise from optically projected shadows of a periodic feature in the inner regions, such as corrugations in the rim of a circumstellar disk. The sequence of nested polar rings draws comparison with the triple-ring system seen around the only naked-eye supernova in recent history: SN1987A.
Minimal Left-Right Symmetric Dark Matter.
Heeck, Julian; Patra, Sudhanwa
2015-09-18
We show that left-right symmetric models can easily accommodate stable TeV-scale dark matter particles without the need for an ad hoc stabilizing symmetry. The stability of a newly introduced multiplet either arises accidentally as in the minimal dark matter framework or comes courtesy of the remaining unbroken Z_{2} subgroup of B-L. Only one new parameter is introduced: the mass of the new multiplet. As minimal examples, we study left-right fermion triplets and quintuplets and show that they can form viable two-component dark matter. This approach is, in particular, valid for SU(2)×SU(2)×U(1) models that explain the recent diboson excess at ATLAS in terms of a new charged gauge boson of mass 2 TeV.
Quasiaxially symmetric stellarators with three field periods
International Nuclear Information System (INIS)
Garabedian, P.; Ku, L.
1999-01-01
Compact hybrid configurations with two field periods have been studied recently as candidates for a proof of principle experiment at the Princeton Plasma Physics Laboratory. This project has led us to the discovery of a family of quasiaxially symmetric stellarators with three field periods that have significant advantages, although their aspect ratios are a little larger. They have reversed shear and perform better in a local analysis of ballooning modes. Nonlinear equilibrium and stability calculations predict that the average beta limit will be at least as high as 4% if the bootstrap current turns out to be as big as that expected in comparable tokamaks. The concept relies on a combination of helical fields and bootstrap current to achieve adequate rotational transform at low aspect ratio. copyright 1999 American Institute of Physics
Primordial two-component maximally symmetric inflation
Enqvist, K.; Nanopoulos, D. V.; Quirós, M.; Kounnas, C.
1985-12-01
We propose a two-component inflation model, based on maximally symmetric supergravity, where the scales of reheating and the inflation potential at the origin are decoupled. This is possible because of the second-order phase transition from SU(5) to SU(3)×SU(2)×U(1) that takes place when φ≅φcinflation at the global minimum, and leads to a reheating temperature TR≅(1015-1016) GeV. This makes it possible to generate baryon asymmetry in the conventional way without any conflict with experimental data on proton lifetime. The mass of the gravitinos is m3/2≅1012 GeV, thus avoiding the gravitino problem. Monopoles are diluted by residual inflation in the broken phase below the cosmological bounds if φcUSA.
Lovelock black holes with maximally symmetric horizons
Energy Technology Data Exchange (ETDEWEB)
Maeda, Hideki; Willison, Steven; Ray, Sourya, E-mail: hideki@cecs.cl, E-mail: willison@cecs.cl, E-mail: ray@cecs.cl [Centro de Estudios CientIficos (CECs), Casilla 1469, Valdivia (Chile)
2011-08-21
We investigate some properties of n( {>=} 4)-dimensional spacetimes having symmetries corresponding to the isometries of an (n - 2)-dimensional maximally symmetric space in Lovelock gravity under the null or dominant energy condition. The well-posedness of the generalized Misner-Sharp quasi-local mass proposed in the past study is shown. Using this quasi-local mass, we clarify the basic properties of the dynamical black holes defined by a future outer trapping horizon under certain assumptions on the Lovelock coupling constants. The C{sup 2} vacuum solutions are classified into four types: (i) Schwarzschild-Tangherlini-type solution; (ii) Nariai-type solution; (iii) special degenerate vacuum solution; and (iv) exceptional vacuum solution. The conditions for the realization of the last two solutions are clarified. The Schwarzschild-Tangherlini-type solution is studied in detail. We prove the first law of black-hole thermodynamics and present the expressions for the heat capacity and the free energy.
Polyhomogeneous expansions from time symmetric initial data
Gasperín, E.; Valiente Kroon, J. A.
2017-10-01
We make use of Friedrich’s construction of the cylinder at spatial infinity to relate the logarithmic terms appearing in asymptotic expansions of components of the Weyl tensor to the freely specifiable parts of time symmetric initial data sets for the Einstein field equations. Our analysis is based on the assumption that a particular type of formal expansions near the cylinder at spatial infinity corresponds to the leading terms of actual solutions to the Einstein field equations. In particular, we show that if the Bach tensor of the initial conformal metric does not vanish at the point at infinity then the most singular component of the Weyl tensor decays near null infinity as O(\\tilde{r}-3\\ln \\tilde{r}) so that spacetime will not peel. We also provide necessary conditions on the initial data which should lead to a peeling spacetime. Finally, we show how to construct global spacetimes which are candidates for non-peeling (polyhomogeneous) asymptotics.
From Symmetric Glycerol Derivatives to Dissymmetric Chlorohydrins
Directory of Open Access Journals (Sweden)
Gemma Villorbina
2011-03-01
Full Text Available The anticipated worldwide increase in biodiesel production will result in an accumulation of glycerol for which there are insufficient conventional uses. The surplus of this by-product has increased rapidly during the last decade, prompting a search for new glycerol applications. We describe here the synthesis of dissymmetric chlorohydrin esters from symmetric 1,3-dichloro-2-propyl esters obtained from glycerol. We studied the influence of two solvents: 1,4-dioxane and 1-butanol and two bases: sodium carbonate and 1-butylimidazole, on the synthesis of dissymmetric chlorohydrin esters. In addition, we studied the influence of other bases (potassium and lithium carbonates in the reaction using 1,4-dioxane as the solvent. The highest yield was obtained using 1,4-dioxane and sodium carbonate.
Bidding behavior in a symmetric Chinese auction
Directory of Open Access Journals (Sweden)
Mauricio Benegas
2015-01-01
Full Text Available This paper purposes a symmetric all-pay auction where the bidders compete neither for an object nor the object itself but for a lottery on receive. That lottery is determined endogenously through the bids. This auction is known as chance auction or more popularly as Chinese auction. The model considers the possibility that for some bidders the optimal strategy is to bid zero and to rely on luck. It showed that bidders become less aggressive when the lottery satisfies a variational condition. It was also shown that luck factor is decisive to determine if the expected payoff in Chinese auction is bigger or smaller than expected payoff in standard all-pay auction.
Canonical quantization of static spherically symmetric geometries
International Nuclear Information System (INIS)
Christodoulakis, T; Dimakis, N; Terzis, P A; Doulis, G; Grammenos, Th; Melas, E; Spanou, A
2013-01-01
The conditional symmetries of the reduced Einstein–Hilbert action emerging from a static, spherically symmetric geometry are used as supplementary conditions on the wave function. Based on their integrability conditions, only one of the three existing symmetries can be consistently imposed, while the unique Casimir invariant, being the product of the remaining two symmetries, is calculated as the only possible second condition on the wave function. This quadratic integral of motion is identified with the reparametrization generator, as an implication of the uniqueness of the dynamical evolution, by fixing a suitable parametrization of the r-lapse function. In this parametrization, the determinant of the supermetric plays the role of the mesure. The combined Wheeler – DeWitt and linear conditional symmetry equations are analytically solved. The solutions obtained depend on the product of the two ''scale factors''
Cosmic ray antimatter and baryon symmetric cosmology
Stecker, F. W.; Protheroe, R. J.; Kazanas, D.
1982-01-01
The relative merits and difficulties of the primary and secondary origin hypotheses for the observed cosmic-ray antiprotons, including the new low-energy measurement of Buffington, et al. We conclude that the cosmic-ray antiproton data may be evidence for antimatter galaxies and baryon symmetric cosmology. The present bar P data are consistent with a primary extragalactic component having /p=/equiv 1+/- 3.2/0.7x10 = to the -4 independent of energy. We propose that the primary extragalactic cosmic ray antiprotons are most likely from active galaxies and that expected disintegration of bar alpha/alpha ban alpha/alpha. We further predict a value for ban alpha/alpha =/equiv 10 to the -5, within range of future cosmic ray detectors.
Symmetric Topological Phases and Tensor Network States
Jiang, Shenghan
Classification and simulation of quantum phases are one of main themes in condensed matter physics. Quantum phases can be distinguished by their symmetrical and topological properties. The interplay between symmetry and topology in condensed matter physics often leads to exotic quantum phases and rich phase diagrams. Famous examples include quantum Hall phases, spin liquids and topological insulators. In this thesis, I present our works toward a more systematically understanding of symmetric topological quantum phases in bosonic systems. In the absence of global symmetries, gapped quantum phases are characterized by topological orders. Topological orders in 2+1D are well studied, while a systematically understanding of topological orders in 3+1D is still lacking. By studying a family of exact solvable models, we find at least some topological orders in 3+1D can be distinguished by braiding phases of loop excitations. In the presence of both global symmetries and topological orders, the interplay between them leads to new phases termed as symmetry enriched topological (SET) phases. We develop a framework to classify a large class of SET phases using tensor networks. For each tensor class, we can write down generic variational wavefunctions. We apply our method to study gapped spin liquids on the kagome lattice, which can be viewed as SET phases of on-site symmetries as well as lattice symmetries. In the absence of topological order, symmetry could protect different topological phases, which are often referred to as symmetry protected topological (SPT) phases. We present systematic constructions of tensor network wavefunctions for bosonic symmetry protected topological (SPT) phases respecting both onsite and spatial symmetries.
The radiation chemistry of symmetric aliphatic polyesters
International Nuclear Information System (INIS)
Babanalbandi, A.; Hill, D.J.T.; Pomery, P.J.; Whittaker, A.K.
1996-01-01
Full text: Naturally occurring, symmetric polyesters, including polyglycolic acid, polylactic acid and polyhydroxybutyrate, have found biomedical applications in areas as diverse as the controlled release of pharmaceuticals and the manufacture of surgical sutures. As biomedical products, the materials require sterilization by high energy radiation. This has provided the motivation for the present work. D'Alelio et al. have reported that linear, asymmetric polyesters undergo scission on irradiation, but that branched polyesters containing a methyl group in the diol segments undergo crosslinking. However, for the symmetric polyhydroxybutyrate, Carswell-Pomerantz et al. have reported that only scission occurs on radiolysis, with the evolution of CO and CO 2 as a result of the loss of ester linkages. These workers also found that G(CO + CO 2 ) was approximately equal to G(S) for this polyester. By contrast, Collett et al. have reported that G(S) = 1.26 and G(X) = 0.53 for polylactic acid, which indicates that the polymer undergoes nett crosslinking on radiolysis to form a gel. They have also reported that poly(lactic-co-glycolic acid) should form a gel on radiolysis, since G(S) = 1.66 and G(X) = 0.65 for a 1:1 copolymer composition. In the present work the radiolysis of polylactic acid and poly(lactic-co-glycolic acid) have been reinvestigated in order to resolve the differences between the work of Collett et al. and that of Carswell-Pomerantz et al. In these studies, ESR has been used to study the radicals formed, GPC has been used to investigate scission and crosslinking, GC has been used to study the small molecule volatile products and NMR spectroscopy has been used to identify and measure the new chemical structures formed in the polymers
FFLP problem with symmetric trapezoidal fuzzy numbers
Directory of Open Access Journals (Sweden)
Reza Daneshrad
2015-04-01
Full Text Available The most popular approach for solving fully fuzzy linear programming (FFLP problems is to convert them into the corresponding deterministic linear programs. Khan et al. (2013 [Khan, I. U., Ahmad, T., & Maan, N. (2013. A simplified novel technique for solving fully fuzzy linear programming problems. Journal of Optimization Theory and Applications, 159(2, 536-546.] claimed that there had been no method in the literature to find the fuzzy optimal solution of a FFLP problem without converting it into crisp linear programming problem, and proposed a technique for the same. Others showed that the fuzzy arithmetic operation used by Khan et al. (2013 had some problems in subtraction and division operations, which could lead to misleading results. Recently, Ezzati et al. (2014 [Ezzati, R., Khorram, E., & Enayati, R. (2014. A particular simplex algorithm to solve fuzzy lexicographic multi-objective linear programming problems and their sensitivity analysis on the priority of the fuzzy objective functions. Journal of Intelligent and Fuzzy Systems, 26(5, 2333-2358.] defined a new operation on symmetric trapezoidal fuzzy numbers and proposed a new algorithm to find directly a lexicographic/preemptive fuzzy optimal solution of a fuzzy lexicographic multi-objective linear programming problem by using new fuzzy arithmetic operations, but their model was not fully fuzzy optimization. In this paper, a new method, by using Ezzati et al. (2014’s fuzzy arithmetic operation and a fuzzy version of simplex algorithm, is proposed for solving FFLP problem whose parameters are represented by symmetric trapezoidal fuzzy number without converting the given problem into crisp equivalent problem. By using the proposed method, the fuzzy optimal solution of FFLP problem can be easily obtained. A numerical example is provided to illustrate the proposed method.
Axially symmetric Lorentzian wormholes in general relativity
International Nuclear Information System (INIS)
Schein, F.
1997-11-01
The field equations of Einstein's theory of general relativity, being local, do not fix the global structure of space-time. They admit topologically non-trivial solutions, including spatially closed universes and the amazing possibility of shortcuts for travel between distant regions in space and time - so-called Lorentzian wormholes. The aim of this thesis is to (mathematically) construct space-times which contain traversal wormholes connecting arbitrary distant regions of an asymptotically flat or asymptotically de Sitter universe. Since the wormhole mouths appear as two separate masses in the exterior space, space-time can at best be axially symmetric. We eliminate the non-staticity caused by the gravitational attraction of the mouths by anchoring them by strings held at infinity or, alternatively, by electric repulsion. The space-times are obtained by surgically grafting together well-known solutions of Einstein's equations along timelike hypersurfaces. This surgery naturally concentrates a non-zero stress-energy tensor on the boundary between the two space-times which can be investigated by using the standard thin shell formalism. It turns out that, when using charged black holes, the provided constructions are possible without violation of any of the energy conditions. In general, observers living in the axially symmetric, asymptotically flat (respectively asymptotically de Sitter) region axe able to send causal signals through the topologically non-trivial region. However, the wormhole space-times contain closed timelike curves. Because of this explicit violation of global hyperbolicity these models do not serve as counterexamples to known topological censorship theorems. (author)
Magnetospectroscopy of symmetric and anti-symmetric states in double quantum wells
Marchewka, M.; Sheregii, E. M.; Tralle, I.; Ploch, D.; Tomaka, G.; Furdak, M.; Kolek, A.; Stadler, A.; Mleczko, K.; Zak, D.; Strupinski, W.; Jasik, A.; Jakiela, R.
2008-02-01
The experimental results obtained for magnetotransport in the InGaAs/InAlAs double quantum well (DQW) structures of two different shapes of wells are reported. A beating effect occurring in the Shubnikov-de Haas (SdH) oscillations was observed for both types of structures at low temperatures in the parallel transport when the magnetic field was perpendicular to the layers. An approach for the calculation of the Landau level energies for DQW structures was developed and then applied to the analysis and interpretation of the experimental data related to the beating effect. We also argue that in order to account for the observed magnetotransport phenomena (SdH and integer quantum Hall effect), one should introduce two different quasi-Fermi levels characterizing two electron subsystems regarding the symmetry properties of their states, symmetric and anti-symmetric ones, which are not mixed by electron-electron interaction.
Entangling capabilities of symmetric two-qubit gates
Indian Academy of Sciences (India)
Com- putational investigation of entanglement of such ensembles is therefore impractical for ... the computational complexity. Pairs of spin-1 ... tensor operators which can also provide different symmetric logic gates for quantum pro- ... that five of the eight, two-qubit symmetric quantum gates expressed in terms of our newly.
SUSY formalism for the symmetric double well potential
Indian Academy of Sciences (India)
symmetric double well potential barrier we have obtained a class of exactly solvable potentials subject to moving boundary condition. The eigenstates are also obtained by the same technique. Keywords. SUSY; moving boundary condition; exactly solvable; symmetric double well; NH3 molecule. PACS Nos 02.30.Ik; 03.50.
A New Formulation for Symmetric Implicit Runge-Kutta-Nystrom ...
African Journals Online (AJOL)
In this paper we derive symmetric stable Implicit Runge-Kutta –Nystrom Method for the Integration of General Second Order ODEs by using the collocation approach.The block hybrid method obtained by the evaluation of the continuous interpolant at different nodes of the polynomial is symmetric and suitable for stiff intial ...
Crossing symmetric solution of the Chew-Low equation
International Nuclear Information System (INIS)
McLeod, R.J.; Ernst, D.J.
1982-01-01
An N/D dispersion theory is developed which solves crossing symmetric Low equations. The method is used to generate crossing symmetric solutions to the Chew-Low model. We show why the technique originally proposed by Chew and Low was incapable of producing solutions. (orig.)
Sparse symmetric preconditioners for dense linear systems in electromagnetism
Carpentieri, Bruno; Duff, Iain S.; Giraud, Luc; Monga Made, M. Magolu
2004-01-01
We consider symmetric preconditioning strategies for the iterative solution of dense complex symmetric non-Hermitian systems arising in computational electromagnetics. In particular, we report on the numerical behaviour of the classical incomplete Cholesky factorization as well as some of its recent
Stability of transparent spherically symmetric thin shells and wormholes
International Nuclear Information System (INIS)
Ishak, Mustapha; Lake, Kayll
2002-01-01
The stability of transparent spherically symmetric thin shells (and wormholes) to linearized spherically symmetric perturbations about static equilibrium is examined. This work generalizes and systematizes previous studies and explores the consequences of including the cosmological constant. The approach shows how the existence (or not) of a domain wall dominates the landscape of possible equilibrium configurations
Coupled dilaton and electromagnetic field in cylindrically symmetric ...
Indian Academy of Sciences (India)
The dilaton black hole solutions have attracted considerable attention for the ... theory and study the corresponding cylindrically symmetric spacetime, where .... where Йm and Йe are integration constants to be interpreted later as the ..... feature is apparent for the cylindrically symmetric spacetime in the presence of the dila-.
Radon transformation on reductive symmetric spaces: support theorems
Kuit, J.J.|info:eu-repo/dai/nl/313872589
2011-01-01
In this thesis we introduce a class of Radon transforms for reductive symmetric spaces, including the horospherical transforms, and study some of their properties. In particular we obtain a generalization of Helgason's support theorem for the horospherical transform on a Riemannian symmetric space.
New approach to solve symmetric fully fuzzy linear systems
Indian Academy of Sciences (India)
In this paper, we present a method to solve fully fuzzy linear systems with symmetric coefﬁcient matrix. The symmetric coefﬁcient matrix is decomposed into two systems of equations by using Cholesky method and then a solution can be obtained. Numerical examples are given to illustrate our method.
Synthesis & Characterization of New bis-Symmetrical Adipoyl ...
African Journals Online (AJOL)
Full Title: Synthesis and Characterization of New bis-Symmetrical Adipoyl, Terepthaloyl, Chiral Diimido-di-L-alanine Diesters and Chiral Phthaloyl-L-alanine Ester of Tripropoxy p-tert-Butyl Calix[4]arene and Study of Their Hosting Ability for Alanine and Na+. Bis-symmetrical tripropoxy p-tert-butyl calix[4]arene esters were ...
FACES WITH LARGE DIAMETER ON THE SYMMETRICAL TRAVELING SALESMAN POLYTOPE
SIERKSMA, G; TIJSSEN, GA
This paper deals with the symmetric traveling salesman polytope and contains three main theorems. The first one gives a new characterization of (non)adjacency. Based on this characterization a new upper bound for the diameter of the symmetric traveling salesman polytope (conjectured to be 2 by M.
Symmetric metamaterials based on flower-shaped structure
International Nuclear Information System (INIS)
Tuong, P.V.; Park, J.W.; Rhee, J.Y.; Kim, K.W.; Cheong, H.; Jang, W.H.; Lee, Y.P.
2013-01-01
We proposed new models of metamaterials (MMs) based on a flower-shaped structure (FSS), whose “meta-atoms” consist of two flower-shaped metallic parts separated by a dielectric layer. Like the non-symmetric MMs based on cut-wire-pairs or electric ring resonators, the symmetrical FSS demonstrates the negative permeability at GHz frequencies. Employing the results, we designed a symmetric negative-refractive-index MM [a symmetric combined structure (SCS)], which is composed of FSSs and cross continuous wires. The MM properties of the FSS and the SCS are presented numerically and experimentally. - Highlights: • A new designed of sub-wavelength metamaterial, flower-shaped structure was proposed. • Flower-shaped meta-atom illustrated effective negative permeability. • Based on the meta-atom, negative refractive index was conventionally gained. • Negative refractive index was demonstrated with symmetric properties for electromagnetic wave. • Dimensional parameters were studied under normal electromagnetic wave
Symmetric weak ternary quantum homomorphic encryption schemes
Wang, Yuqi; She, Kun; Luo, Qingbin; Yang, Fan; Zhao, Chao
2016-03-01
Based on a ternary quantum logic circuit, four symmetric weak ternary quantum homomorphic encryption (QHE) schemes were proposed. First, for a one-qutrit rotation gate, a QHE scheme was constructed. Second, in view of the synthesis of a general 3 × 3 unitary transformation, another one-qutrit QHE scheme was proposed. Third, according to the one-qutrit scheme, the two-qutrit QHE scheme about generalized controlled X (GCX(m,n)) gate was constructed and further generalized to the n-qutrit unitary matrix case. Finally, the security of these schemes was analyzed in two respects. It can be concluded that the attacker can correctly guess the encryption key with a maximum probability pk = 1/33n, thus it can better protect the privacy of users’ data. Moreover, these schemes can be well integrated into the future quantum remote server architecture, and thus the computational security of the users’ private quantum information can be well protected in a distributed computing environment.
Skyrmions and vector mesons: a symmetric approach
International Nuclear Information System (INIS)
Caldi, D.G.
1984-01-01
We propose an extension of the effective, low-energy chiral Lagrangian known as the Skyrme model, to one formulated by a non-linear sigma model generalized to include vector mesons in a symmetric way. The model is based on chiral SU(6) x SU(6) symmetry spontaneously broken to static SU(6). The rho and other vector mesons are dormant Goldstone bosons since they are in the same SU(6) multiplet as the pion and other pseudoscalars. Hence the manifold of our generalized non-linear sigma model is the coset space (SU(6) x SU(6))/Su(6). Relativistic effects, via a spin-dependent mass term, break the static SU(6) and give the vectors a mass. The model can then be fully relativistic and covariant. The lowest-lying Skyrmion in this model is the whole baryonic 56-plet, which splits into the octet and decuplet in the presence of relativistic SU(6)-breaking. Due to the built-in SU(6) and the presence of vector mesons, the model is expected to have better phenomenological results, as well as providing a conceptually more unified picture of mesons and baryons. 29 references
Randomized Symmetric Crypto Spatial Fusion Steganographic System
Directory of Open Access Journals (Sweden)
Viswanathan Perumal
2016-06-01
Full Text Available The image fusion steganographic system embeds encrypted messages in decomposed multimedia carriers using a pseudorandom generator but it fails to evaluate the contents of the cover image. This results in the secret data being embedded in smooth regions, which leads to visible distortion that affects the imperceptibility and confidentiality. To solve this issue, as well as to improve the quality and robustness of the system, the Randomized Symmetric Crypto Spatial Fusion Steganography System is proposed in this study. It comprises three-subsystem bitwise encryption, spatial fusion, and bitwise embedding. First, bitwise encryption encrypts the message using bitwise operation to improve the confidentiality. Then, spatial fusion decomposes and evaluates the region of embedding on the basis of sharp intensity and capacity. This restricts the visibility of distortion and provides a high embedding capacity. Finally, the bitwise embedding system embeds the encrypted message through differencing the pixels in the region by 1, checking even or odd options and not equal to zero constraints. This reduces the modification rate to avoid distortion. The proposed heuristic algorithm is implemented in the blue channel, to which the human visual system is less sensitive. It was tested using standard IST natural images with steganalysis algorithms and resulted in better quality, imperceptibility, embedding capacity and invulnerability to various attacks compared to other steganographic systems.
Triple symmetric key cryptosystem for data security
Fuzail, C. Md; Norman, Jasmine; Mangayarkarasi, R.
2017-11-01
As the technology is getting spreads in the macro seconds of speed and in which the trend changing era from human to robotics the security issue is also getting increased. By means of using machine attacks it is very easy to break the cryptosystems in very less amount of time. Cryptosystem is a process which provides the security in all sorts of processes, communications and transactions to be done securely with the help of electronical mechanisms. Data is one such thing with the expanded implication and possible scraps over the collection of data to secure predominance and achievement, Information Security is the process where the information is protected from invalid and unverified accessibilities and data from mishandling. So the idea of Information Security has risen. Symmetric key which is also known as private key.Whereas the private key is mostly used to attain the confidentiality of data. It is a dynamic topic which can be implemented over different applications like android, wireless censor networks, etc. In this paper, a new mathematical manipulation algorithm along with Tea cryptosystem has been implemented and it can be used for the purpose of cryptography. The algorithm which we proposed is straightforward and more powerful and it will authenticate in harder way and also it will be very difficult to break by someone without knowing in depth about its internal mechanisms.
Experimental pseudo-symmetric trap EPSILON
International Nuclear Information System (INIS)
Skovoroda, A.A.; Arsenin, V.V.; Dlougach, E.D.; Kulygin, V.M.; Kuyanov, A.Yu.; Timofeev, A.V.; Zhil'tsov, V.A.; Zvonkov, A.V.
2001-01-01
Within the framework of the conceptual project 'Adaptive Plasma EXperiment' a trap with the closed magnetic field lines 'Experimental Pseudo-Symmetric trap' is examined. The project APEX is directed at the theoretical and experimental development of physical foundations for stationary thermonuclear reactor on the basis of an alternative magnetic trap with tokamak-level confinement of high β plasma. The fundamental principle of magnetic field pseudosymmetry that should be satisfied for plasma to have tokamak-like confinement is discussed. The calculated in paraxial approximation examples of pseudosymmetric curvilinear elements with poloidal direction of B isolines are adduced. The EPSILON trap consisting of two straight axisymmetric mirrors linked by two curvilinear pseudosymmetric elements is considered. The plasma currents are short-circuited within the curvilinear element what increases the equilibrium β. The untraditional scheme of MHD stabilization of a trap with the closed field lines by the use of divertor inserted into axisymmetric mirror is analyzed. The experimental installation EPSILON-OME that is under construction for experimental check of divertor stabilization is discussed. The possibility of ECR plasma production in EPSILON-OME under conditions of high density and small magnetic field is examined. (author)
Left-right symmetric superstring supergravitation
International Nuclear Information System (INIS)
Burova, M.V.; Ter-Martirosyan, K.E.
1988-01-01
A left-right (L-R) symmetric model of four-dimensional supergravitation with a SO(10) gauge group obtained as the low-energy limit is superstring theory is considered. The spectrum of the gauge fields and their interactions are in agreement with the Weinberg-Salam theory. In addition, the model includes heavy W R ± and Z μ ' bosons. Beside the N g =3 generations of the 16-plets the SO(10) model includes the fragments of such generations which play the role of Higgs particles and also scalar chiral filds, the number of which exceeds by one the number of generations. As a result the neutrinos of each generation obtain a stable small Majorana mass. It is shown that the scalar field potential leads to spontaneous violation of the SU(2) R group and L-R symmetry and at low energies the standard Weinberg-Salam theory appears. However, reasonable values of X bosons masses M x and sun 2 Θ W (Θ W is the Weinberg angle) can be obtained in the model only in the case of high mass scale M R ∼10 10 -10 12 GeV of the right group SU(2) R violation
Canonic FFT flow graphs for real-valued even/odd symmetric inputs
Lao, Yingjie; Parhi, Keshab K.
2017-12-01
Canonic real-valued fast Fourier transform (RFFT) has been proposed to reduce the arithmetic complexity by eliminating redundancies. In a canonic N-point RFFT, the number of signal values at each stage is canonic with respect to the number of signal values, i.e., N. The major advantage of the canonic RFFTs is that these require the least number of butterfly operations and only real datapaths when mapped to architectures. In this paper, we consider the FFT computation whose inputs are not only real but also even/odd symmetric, which indeed lead to the well-known discrete cosine and sine transforms (DCTs and DSTs). Novel algorithms for generating the flow graphs of canonic RFFTs with even/odd symmetric inputs are proposed. It is shown that the proposed algorithms lead to canonic structures with N/2 +1 signal values at each stage for an N-point real even symmetric FFT (REFFT) or N/2 -1 signal values at each stage for an N-point RFFT real odd symmetric FFT (ROFFT). In order to remove butterfly operations, several twiddle factor transformations are proposed in this paper. We also discuss the design of canonic REFFT for any composite length. Performances of the canonic REFFT/ROFFT are also discussed. It is shown that the flow graph of canonic REFFT/ROFFT has less number of interconnections, less butterfly operations, and less twiddle factor operations, compared to prior works.
Modelling the air flow in symmetric and asymmetric street canyons
Energy Technology Data Exchange (ETDEWEB)
Santiago, J.L.; Martin, F. [Research Center for Energy, Environment and Technology (CIEMAT), Madrid (Spain). Fossil Fuels Dept., Numerical Simulation and Modelling Program
2004-07-01
In recent years a large amount of research has been conducted on urban scale and street canyon. Control of air quality inside cities is important for human health. To achieve this objective, street canyon modelling plays a significant role. Pollutant dispersion inside canyons are determined by wind flow around this complex geometry. Experimental investigations have been made by means of field measurements such as Vachon, G. et al. or wind tunnel experiences as Meroney, R.N. et al. or Kastner-Klein, P. and E.J. Plate. In many of these researches, they have used CFD models in several configurations, for instance Assimakopoulos, V.D. et al. or Sini, J.-F. et al. These models are based on a numerical resolution of Navier-Stokes equations with a turbulence closure. In this study, the aim is contribute to the understanding of air circulation inside street canyons. In order to achieve this purpose, several configurations of canyons are investigated. Two-dimensional sequences of real-scale street canyons (order to obstacles height is meters) with different features (symmetric canyons and asymmetric canyons forming step-up and step-down notch configurations) are simulated. These general configurations are modified to investigate some parameters such as aspect ratio, W/H, where W is the width of street and H is the height of buildings. Flows with high Reynolds numbers are modelling. FLUENT CFD software is used. (orig.)
Mechanisms and Management of Diabetic Painful Distal Symmetrical Polyneuropathy
Tesfaye, Solomon; Boulton, Andrew J.M.; Dickenson, Anthony H.
2013-01-01
Although a number of the diabetic neuropathies may result in painful symptomatology, this review focuses on the most common: chronic sensorimotor distal symmetrical polyneuropathy (DSPN). It is estimated that 15–20% of diabetic patients may have painful DSPN, but not all of these will require therapy. In practice, the diagnosis of DSPN is a clinical one, whereas for longitudinal studies and clinical trials, quantitative sensory testing and electrophysiological assessment are usually necessary. A number of simple numeric rating scales are available to assess the frequency and severity of neuropathic pain. Although the exact pathophysiological processes that result in diabetic neuropathic pain remain enigmatic, both peripheral and central mechanisms have been implicated, and extend from altered channel function in peripheral nerve through enhanced spinal processing and changes in many higher centers. A number of pharmacological agents have proven efficacy in painful DSPN, but all are prone to side effects, and none impact the underlying pathophysiological abnormalities because they are only symptomatic therapy. The two first-line therapies approved by regulatory authorities for painful neuropathy are duloxetine and pregabalin. α-Lipoic acid, an antioxidant and pathogenic therapy, has evidence of efficacy but is not licensed in the U.S. and several European countries. All patients with DSPN are at increased risk of foot ulceration and require foot care, education, and if possible, regular podiatry assessment. PMID:23970715
Natural Circulation Characteristics of a Symmetric Loop under Inclined Conditions
Directory of Open Access Journals (Sweden)
Xingtuan Yang
2014-01-01
Full Text Available Natural circulation is an important process for primary loops of some marine integrated reactors. The reactor works under inclined conditions when severe accidents happen to the ship. In this paper, to investigate the characteristics of natural circulation, experiments were conducted in a symmetric loop under the inclined angle of 0~45°. A CFD model was also set up to predict the behaviors of the loop beyond the experimental scope. Total circulation flow rate decreases with the increase of inclined angle. Meanwhile one circulation is depressed while the other is enhanced, and accordingly the disparity between the branch circulations arises and increases with the increase of inclined angle. Circulation only takes place in one branch circuit at large inclined angle. Also based on the CFD model, the influences of flow resistance distribution and loop configuration on natural circulation are predicted. The numerical results show that to design the loop with the configuration of big altitude difference and small width, it is favorable to reduce the influence of inclination; however too small loop width will cause severe reduction of circulation ability at large angle inclination.
Reaction mechanism for the symmetric breakup of 24Mg following an interaction with 12C
International Nuclear Information System (INIS)
Gyapong, G.J.; Watson, D.L.; Catford, W.N.; Clarke, N.M.; Bennett, S.J.; Freer, M.; Fulton, B.R.; Jones, C.D.; Leddy, M.; Murgatroyd, J.T.; Rae, W.D.M.; Simmons, P.
1994-01-01
Data on the yield of the symmetric breakup of 24 Mg as a function of beam energy are presented and compared with detailed calculations of the energy dependence. The 24 Mg states seen in symmetric breakup agree with previously observed breakup states having spin and parities J π =4 + ,(6 + ),8 + . The data allow the variations of yield for indivual states to be judged, as the beam energy is varied. The variation in the yield of the 4 + states is compared in detail with calculations assuming several possible compound nuclear or direct reaction mechanisms. It is concluded that a massive ( 12 C) transfer or a simple statistical compound process are unlikely mechanisms, but that each of several other mechanisms is consistent with the data. ((orig.))
Diabetic Retinopathy Is Associated With Elevated Serum Asymmetric and Symmetric Dimethylarginines
Abhary, Sotoodeh; Kasmeridis, Nicholas; Burdon, Kathryn P.; Kuot, Abraham; Whiting, Malcolm J.; Yew, Wai Ping; Petrovsky, Nikolai; Craig, Jamie E.
2009-01-01
OBJECTIVE Asymmetric dimethylarginine (ADMA), symmetric dimethylarginine (SDMA), and l-arginine directly influence nitric oxide production. Our objective was to test whether serum ADMA, SDMA, or l-arginine levels correlate with diabetic retinopathy subtype or severity. RESEARCH DESIGN AND METHODS A total of 162 subjects with type 1 diabetes and 343 with type 2 diabetes, of whom 329 subjects had no diabetic retinopathy, 27 had nonproliferative diabetic retinopathy (NPDR), 101 had proliferative...
Survival and transmission of symmetrical chromosomal aberrations
International Nuclear Information System (INIS)
Savage, J.R.K.
1979-01-01
The interaction between the lesions to produce chromosomal structural changes may be either asymmetrical (A) or symmetrical (S). In A, one or more acentric fragments are always produced, and there may also be the mechanical separation problems resulting from bridges at anaphase, while S-changes never produce fragment, and pose no mechanical problem in cell division. If A and S events occur with equal frequency, it might be an indication that they are truly the alternative modes of lesion interaction. Unstimulated lymphocytes were irradiated with 2.68 Gy 250 kV X-ray, and metaphases were sampled at 50 h after the stimulation. Preparations were complete diploid cells, and any obvious second division cells were rejected. So far as dermal repair and fibroblast functions are concerned, aberration burden seems to have little consequence from the view-point of the long-term survival in vivo. Large numbers of aberrations (mainly S translocation and terminal deletion) were found in the samples taken up to 60 years after therapy. Skin biopsies were removed 1 day and 6 months after irradiation and cultured. In irradiated cells, reciprocal translocations dominated, followed by terminal deletions, then inversions, while no chromosome-type aberration was seen in the control cells. a) The relative occurrence of A : S changes, b) long-term survival in vivo, c) the possibility of in vivo repair, and d) some unusual features of translocation found in Syrian hamsters are reviewed. The relevance or importance of major S events is clearly dependent upon the cells, the tissues or the organisms in which they occur. (Yamashita, S.)
Radon transformation on reductive symmetric spaces:Support theorems
DEFF Research Database (Denmark)
Kuit, Job Jacob
2013-01-01
We introduce a class of Radon transforms for reductive symmetric spaces, including the horospherical transforms, and derive support theorems for these transforms. A reductive symmetric space is a homogeneous space G/H for a reductive Lie group G of the Harish-Chandra class, where H is an open sub...... is based on the relation between the Radon transform and the Fourier transform on G/H, and a Paley–Wiener-shift type argument. Our results generalize the support theorem of Helgason for the Radon transform on a Riemannian symmetric space....
Nilpotent orbits in real symmetric pairs and stationary black holes
International Nuclear Information System (INIS)
Dietrich, Heiko; De Graaf, Willem A.; Ruggeri, Daniele; Trigiante, Mario
2017-01-01
In the study of stationary solutions in extended supergravities with symmetric scalar manifolds, the nilpotent orbits of a real symmetric pair play an important role. In this paper we discuss two approaches to determine the nilpotent orbits of a real symmetric pair. We apply our methods to an explicit example, and thereby classify the nilpotent orbits of (SL 2 (R)) 4 acting on the fourth tensor power of the natural 2-dimensional SL 2 (R)-module. This makes it possible to classify all stationary solutions of the so-called STU-supergravity model. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Color symmetrical superconductivity in a schematic nuclear quark model
DEFF Research Database (Denmark)
Bohr, Henrik; Providencia, C.; da Providencia, J.
2010-01-01
In this letter, a novel BCS-type formalism is constructed in the framework of a schematic QCD inspired quark model, having in mind the description of color symmetrical superconducting states. In the usual approach to color superconductivity, the pairing correlations affect only the quasi-particle...... states of two colors, the single-particle states of the third color remaining unaffected by the pairing correlations. In the theory of color symmetrical superconductivity here proposed, the pairing correlations affect symmetrically the quasi-particle states of the three colors and vanishing net color...
Highly-dispersive electromagnetic induced transparency in planar symmetric metamaterials.
Lu, Xiqun; Shi, Jinhui; Liu, Ran; Guan, Chunying
2012-07-30
We propose, design and experimentally demonstrate highly-dispersive electromagnetically induced transparency (EIT) in planar symmetric metamaterials actively switched and controlled by angles of incidence. Full-wave simulation and measurement results show EIT phenomena, trapped-mode excitations and the associated local field enhancement of two symmetric metamaterials consisting of symmetrically split rings (SSR) and a fishscale (FS) metamaterial pattern, respectively, strongly depend on angles of incidence. The FS metamaterial shows much broader spectral splitting than the SSR metamaterial due to the surface current distribution variation.
Geometric characteristics of aberrations of plane-symmetric optical systems
International Nuclear Information System (INIS)
Lu Lijun; Deng Zhiyong
2009-01-01
The geometric characteristics of aberrations of plane-symmetric optical systems are studied in detail with a wave-aberration theory. It is dealt with as an extension of the Seidel aberrations to realize a consistent aberration theory from axially symmetric to plane-symmetric systems. The aberration distribution is analyzed with the spot diagram of a ray and an aberration curve. Moreover, the root-mean-square value and the centroid of aberration distribution are discussed. The numerical results are obtained with the focusing optics of a toroidal mirror at grazing incidence.
Meissner effect for axially symmetric charged black holes
Gürlebeck, Norman; Scholtz, Martin
2018-04-01
In our previous work [N. Gürlebeck and M. Scholtz, Phys. Rev. D 95, 064010 (2017), 10.1103/PhysRevD.95.064010], we have shown that electric and magnetic fields are expelled from the horizons of extremal, stationary and axially symmetric uncharged black holes; this is called the Meissner effect for black holes. Here, we generalize this result in several directions. First, we allow that the black hole carries charge, which requires a generalization of the definition of the Meissner effect. Next, we introduce the notion of almost isolated horizons, which is weaker than the usual notion of isolated horizons, since the geometry of the former is not necessarily completely time independent. Moreover, we allow the horizon to be pierced by strings, thereby violating the usual assumption on the spherical topology made in the definition of the weakly isolated horizon. Finally, we spell out in detail all assumptions entering the proof and show that the Meissner effect is an inherent property of black holes even in full nonlinear theory.
Constructing exact symmetric informationally complete measurements from numerical solutions
Appleby, Marcus; Chien, Tuan-Yow; Flammia, Steven; Waldron, Shayne
2018-04-01
Recently, several intriguing conjectures have been proposed connecting symmetric informationally complete quantum measurements (SIC POVMs, or SICs) and algebraic number theory. These conjectures relate the SICs to their minimal defining algebraic number field. Testing or sharpening these conjectures requires that the SICs are expressed exactly, rather than as numerical approximations. While many exact solutions of SICs have been constructed previously using Gröbner bases, this method has probably been taken as far as is possible with current computer technology (except in special cases where there are additional symmetries). Here, we describe a method for converting high-precision numerical solutions into exact ones using an integer relation algorithm in conjunction with the Galois symmetries of an SIC. Using this method, we have calculated 69 new exact solutions, including nine new dimensions, where previously only numerical solutions were known—which more than triples the number of known exact solutions. In some cases, the solutions require number fields with degrees as high as 12 288. We use these solutions to confirm that they obey the number-theoretic conjectures, and address two questions suggested by the previous work.
Path integral representation of the symmetric Rosen-Morse potential
International Nuclear Information System (INIS)
Duru, I.H.
1983-09-01
An integral formula for the Green's function of symmetric Rosen-Morse potential is obtained by solving path integrals. The correctly normalized wave functions and bound state energy spectrum are derived. (author)
The geometrical theory of diffraction for axially symmetric reflectors
DEFF Research Database (Denmark)
Rusch, W.; Sørensen, O.
1975-01-01
The geometrical theory of diffraction (GTD) (cf. [1], for example) may be applied advantageously to many axially symmetric reflector antenna geometries. The material in this communication presents analytical, computational, and experimental results for commonly encountered reflector geometries...
Filtering microfluidic bubble trains at a symmetric junction.
Parthiban, Pravien; Khan, Saif A
2012-02-07
We report how a nominally symmetric microfluidic junction can be used to sort all bubbles of an incoming train exclusively into one of its arms. The existence of this "filter" regime is unexpected, given that the junction is symmetric. We analyze this behavior by quantifying how bubbles modulate the hydrodynamic resistance in microchannels and show how speeding up a bubble train whilst preserving its spatial periodicity can lead to filtering at a nominally symmetric junction. We further show how such an asymmetric traffic of bubble trains can be triggered in symmetric geometries by identifying conditions wherein the resistance to flow decreases with an increase in the number of bubbles in the microchannel and derive an exact criterion to predict the same.
Symmetric Pin Diversion Detection using a Partial Defect Detector (PDET)
International Nuclear Information System (INIS)
Sitaraman, S.; Ham, Y.S.
2009-01-01
Since the signature from the Partial Defect Detector (PDET) is principally dependent on the geometric layout of the guide tube locations, the capability of the technique in detecting symmetric diversion of pins needs to be determined. The Monte Carlo simulation study consisted of cases where pins were removed in a symmetric manner and the resulting signatures were examined. In addition to the normalized gamma-to-neutron ratios, the neutron and gamma signatures normalized to their maximum values, were also examined. Examination of the shape of the three curves as well as of the peak-to-valley differences in excess of the maximum expected in intact assemblies, indicated pin diversion. A set of simulations with various symmetric patterns of diversion were examined. The results from these studies indicated that symmetric diversions as low as twelve percent could be detected by this methodology
Systems of Differential Equations with Skew-Symmetric, Orthogonal Matrices
Glaister, P.
2008-01-01
The solution of a system of linear, inhomogeneous differential equations is discussed. The particular class considered is where the coefficient matrix is skew-symmetric and orthogonal, and where the forcing terms are sinusoidal. More general matrices are also considered.
A Paley-Wiener theorem for reductive symmetric spaces
Ban, E.P. van den; Schlichtkrull, H.
2006-01-01
Let X = G/H be a reductive symmetric space and K a maximal compact subgroup of G. The image under the Fourier transform of the space of K-finite compactly supported smooth functions on X is characterized.
Report on the Dynamical Evolution of an Axially Symmetric Quasar ...
Indian Academy of Sciences (India)
retical arguments together with some numerical evidence. The evolution of the orbits is studied, as mass is transported from the disk to the nucleus. ... galaxies and non-axially symmetric quasar models (see Papadopoulos & Caranicolas.
first principles derivation of a stress function for axially symmetric
African Journals Online (AJOL)
HOD
governing partial differential equations of linear isotropic elasticity were reduced to the solution of the biharmonic ... The stress function was then applied to solve the axially symmetric ..... [1] Borg S.K.: Fundamentals of Engineering Elasticity,.
Symmetrization of mathematical model of charge transport in semiconductors
Directory of Open Access Journals (Sweden)
Alexander M. Blokhin
2002-11-01
Full Text Available A mathematical model of charge transport in semiconductors is considered. The model is a quasilinear system of differential equations. A problem of finding an additional entropy conservation law and system symmetrization are solved.
An algebraic approach to the non-symmetric Macdonald polynomial
International Nuclear Information System (INIS)
Nishino, Akinori; Ujino, Hideaki; Wadati, Miki
1999-01-01
In terms of the raising and lowering operators, we algebraically construct the non-symmetric Macdonald polynomials which are simultaneous eigenfunctions of the commuting Cherednik operators. We also calculate Cherednik's scalar product of them
Hardware Realization of Chaos Based Symmetric Image Encryption
Barakat, Mohamed L.
2012-01-01
This thesis presents a novel work on hardware realization of symmetric image encryption utilizing chaos based continuous systems as pseudo random number generators. Digital implementation of chaotic systems results in serious degradations
Experimental technique of calibration of symmetrical air pollution ...
Indian Academy of Sciences (India)
Based on the inherent property of symmetry of air pollution models, a Symmetrical Air Pollution. Model ... process is in compliance with air pollution regula- ..... Ground simulation is achieved through MATLAB package which is based on least-.
Hardware Realization of Chaos-based Symmetric Video Encryption
Ibrahim, Mohamad A.
2013-01-01
This thesis reports original work on hardware realization of symmetric video encryption using chaos-based continuous systems as pseudo-random number generators. The thesis also presents some of the serious degradations caused by digitally
Invariant subspaces in some function spaces on symmetric spaces. II
International Nuclear Information System (INIS)
Platonov, S S
1998-01-01
Let G be a semisimple connected Lie group with finite centre, K a maximal compact subgroup of G, and M=G/K a Riemannian symmetric space of non-compact type. We study the problem of describing the structure of closed linear subspaces in various function spaces on M that are invariant under the quasiregular representation of the group G. We consider the case when M is a symplectic symmetric space of rank 1
Symmetric coupling of four spin-1/2 systems
Suzuki, Jun; Englert, Berthold-Georg
2012-06-01
We address the non-binary coupling of identical angular momenta based upon the representation theory for the symmetric group. A correspondence is pointed out between the complete set of commuting operators and the reference-frame-free subsystems. We provide a detailed analysis of the coupling of three and four spin-1/2 systems and discuss a symmetric coupling of four spin-1/2 systems.
Symmetrized neutron transport equation and the fast Fourier transform method
International Nuclear Information System (INIS)
Sinh, N.Q.; Kisynski, J.; Mika, J.
1978-01-01
The differential equation obtained from the neutron transport equation by the application of the source iteration method in two-dimensional rectangular geometry is transformed into a symmetrized form with respect to one of the angular variables. The discretization of the symmetrized equation leads to finite difference equations based on the five-point scheme and solved by use of the fast Fourier transform method. Possible advantages of the approach are shown on test calculations
Koichi, Shungo; Iwata, Satoru; Uno, Takeaki; Koshino, Hiroyuki; Satoh, Hiroko
2007-01-01
We describe a rigorous and fast algorithm for advanced canonical coding of planar chemical structures based on the algorithm of Faulon et al. (J. Chem. Inf. Comput. Sci. 2004, 44, 427-436). Our algorithm works well even for highly symmetric structures; moreover, an advantage of our algorithm includes providing a rigorous canonical numbering of atoms with a consideration of stereochemistry and recognizing symmetric moieties. The planar structural line notation with the canonical numbering is also fit for use with stereochemical line notation. These capabilities are usable for general purposes in chemical structural coding and are particularly essential for detecting equivalent atoms in NMR studies. This algorithm was implemented on a 13C NMR chemical shift prediction system CAST/CNMR. Applications of the algorithm to several organic compounds demonstrate the practical efficiency of the rigorous coding.
Wu, Lingxia; Li, Ruizhi; Guo, Junling; Zhou, Cheng; Zhang, Wenpei; Wang, Chong; Huang, Yu; Li, Yuanyuan; Liu, Jinping
2013-08-01
Flexible solid-state symmetric supercapacitor was fabricated using MnO2 nanofilms growing directly on carbon cloth as the electrodes and PVA/H3PO4 gel as the electrolyte/separator. The device can be operated at a stable cell-voltage up to 1.4 V, obviously larger than that of conventional solid-state symmetric supercapacitors (≤1 V). It exhibited excellent rate capability with a scan rate as high as 20 V s-1 and a long cyclability (˜60000 cycles) even under severe mechanical deformation. The charge storage mechanism at different scan rates was also quantitatively analyzed.
Directory of Open Access Journals (Sweden)
Lingxia Wu
2013-08-01
Full Text Available Flexible solid-state symmetric supercapacitor was fabricated using MnO2 nanofilms growing directly on carbon cloth as the electrodes and PVA/H3PO4 gel as the electrolyte/separator. The device can be operated at a stable cell-voltage up to 1.4 V, obviously larger than that of conventional solid-state symmetric supercapacitors (≤1 V. It exhibited excellent rate capability with a scan rate as high as 20 V s−1 and a long cyclability (∼60000 cycles even under severe mechanical deformation. The charge storage mechanism at different scan rates was also quantitatively analyzed.
Nasir, M. N. M.; Seman, M. A.; Mezeix, L.; Aminanda, Y.; Rivai, A.; Ali, K. M.
2017-03-01
The residual stresses that develop within fibre-reinforced laminate composites during autoclave processing lead to dimensional warpage known as spring-back deformation. A number of experiments have been conducted on flat laminate composites with unidirectional fibre orientation to examine the effects of both the intrinsic and extrinsic parameters on the warpage. This paper extends the study on to the symmetrical layup effect on spring-back for flat laminate composites. Plies stacked at various symmetrical sequences were fabricated to observe the severity of the resulting warpage. Essentially, the experimental results demonstrated that the symmetrical layups reduce the laminate stiffness in its principal direction compared to the unidirectional laminate thus, raising the spring-back warpage with the exception of the [45/-45]S layup due to its quasi-isotropic property.
Some aspects of symmetrical relativistic cosmology
International Nuclear Information System (INIS)
Goto, M.
1977-01-01
A qualitative study of the cosmological model of Omnes is presented, as well as some numerical results. Studies are made in a chronological or historical way involving several subjects like matter and anti-matter emulsions, density of galactic clusters, the annihilation problem, quasars, etc. One solution for the matter diffusion equation is presented
Cotangent bundles over all the Hermitian symmetric spaces
International Nuclear Information System (INIS)
Arai, Masato; Baba, Kurando
2016-01-01
We construct the N = 2 supersymmetric nonlinear sigma models on the cotangent bundles over all the compact and non-compact Hermitian symmetric spaces. In order to construct them we use the projective superspace formalism which is an N = 2 off-shell superfield formulation in four-dimensional space-time. This formalism allows us to obtain the explicit expression of N = 2 supersymmetric nonlinear sigma models on the cotangent bundles over any Hermitian symmetric spaces in terms of the N =1 superfields, once the Kähler potentials of the base manifolds are obtained. Starting with N = 1 supersymmetric Kähler nonlinear sigma models on the Hermitian symmetric spaces, we extend them into the N = 2 supersymmetric models by using the projective superspace formalism and derive the general formula for the cotangent bundles over all the compact and non-compact Hermitian symmetric spaces. We apply to the formula for the non-compact Hermitian symmetric space E 7 /E 6 × U(1) 1 . (paper)
Optomechanically induced absorption in parity-time-symmetric optomechanical systems
Zhang, X. Y.; Guo, Y. Q.; Pei, P.; Yi, X. X.
2017-06-01
We explore the optomechanically induced absorption (OMIA) in a parity-time- (PT -) symmetric optomechanical system (OMS). By numerically calculating the Lyapunov exponents, we find out the stability border of the PT -symmetric OMS. The results show that in the PT -symmetric phase the system can be either stable or unstable depending on the coupling constant and the decay rate. In the PT -symmetric broken phase the system can have a stable state only for small gain rates. By calculating the transmission rate of the probe field, we find that there is an inverted optomechanically induced transparency (OMIT) at δ =-ωM and an OMIA at δ =ωM for the PT -symmetric optomechanical system. At each side of δ =-ωM there is an absorption window due to the resonance absorption of the two generated supermodes. Comparing with the case of optomechanics coupled to a passive cavity, we find that the active cavity can enhance the resonance absorption. The absorption rate at δ =ωM increases as the coupling strength between the two cavities increases. Our work provides us with a promising platform for controlling light propagation and light manipulation in terms of PT symmetry, which might have potential applications in quantum information processing and quantum optical devices.
A cascaded three-phase symmetrical multistage voltage multiplier
International Nuclear Information System (INIS)
Iqbal, Shahid; Singh, G K; Besar, R; Muhammad, G
2006-01-01
A cascaded three-phase symmetrical multistage Cockcroft-Walton voltage multiplier (CW-VM) is proposed in this report. It consists of three single-phase symmetrical voltage multipliers, which are connected in series at their smoothing columns like string of batteries and are driven by three-phase ac power source. The smoothing column of each voltage multiplier is charged twice every cycle independently by respective oscillating columns and discharged in series through load. The charging discharging process completes six times a cycle and therefore the output voltage ripple's frequency is of sixth order of the drive signal frequency. Thus the proposed approach eliminates the first five harmonic components of load generated voltage ripples and sixth harmonic is the major ripple component. The proposed cascaded three-phase symmetrical voltage multiplier has less than half the voltage ripple, and three times larger output voltage and output power than the conventional single-phase symmetrical CW-VM. Experimental and simulation results of the laboratory prototype are given to show the feasibility of proposed cascaded three-phase symmetrical CW-VM
Problem of the coexistence of several non-Hermitian observables in PT -symmetric quantum mechanics
Czech Academy of Sciences Publication Activity Database
Znojil, Miloslav; Semorádová, Iveta; Růžička, František; Moulla, H.; Leghrib, I.
2017-01-01
Roč. 95, č. 4 (2017), č. článku 042122. ISSN 2469-9926 R&D Projects: GA ČR GA16-22945S Institutional support: RVO:61389005 Keywords : operators * Hilbert space * non-Hermitian Subject RIV: BE - Theoretical Physics OBOR OECD: Atomic, molecular and chemical physics (physics of atoms and molecules including collision, interaction with radiation, magnetic resonances, Mössbauer effect) Impact factor: 2.925, year: 2016
A new approach to spherically symmetric junction surfaces and the matching of FLRW regions
International Nuclear Information System (INIS)
Kirchner, U
2004-01-01
We investigate timelike junctions (with surface layer) between spherically symmetric solutions of the Einstein-field equation. In contrast to previous investigations, this is done in a coordinate system in which the junction surface motion is absorbed in the metric, while all coordinates are continuous at the junction surface. The evolution equations for all relevant quantities are derived. We discuss the no-surface layer case (boundary surface) and study the behaviour for small surface energies. It is shown that one should expect cases in which the speed of light is reached within a finite proper time. We carefully discuss necessary and sufficient conditions for a possible matching of spherically symmetric sections. For timelike junctions between spherically symmetric spacetime sections we show explicitly that the time component of the Lanczos equation always reduces to an identity (independent of the surface equation of state). The results are applied to the matching of Friedmann-LemaItre-Robertson-Walker (FLRW) models. We discuss 'vacuum bubbles' and closed-open junctions in detail. As illustrations several numerical integration results are presented, some of them indicate that (observers comoving with) the junction surface can reach the speed of light within a finite time
Ghatak, Ananya; Das, Tanmoy
2018-01-01
Recently developed parity (P ) and time-reversal (T ) symmetric non-Hermitian systems govern a rich variety of new and characteristically distinct physical properties, which may or may not have a direct analog in their Hermitian counterparts. We study here a non-Hermitian, PT -symmetric superconducting Hamiltonian that possesses a real quasiparticle spectrum in the PT -unbroken region of the Brillouin zone. Within a single-band mean-field theory, we find that real quasiparticle energies are possible when the superconducting order parameter itself is either Hermitian or anti-Hermitian. Within the corresponding Bardeen-Cooper-Schrieffer (BCS) theory, we find that several properties are characteristically distinct and novel in the non-Hermitian pairing case than its Hermitian counterpart. One of our significant findings is that while a Hermitian superconductor gives a second-order phase transition, the non-Hermitian one produces a robust first-order phase transition. The corresponding thermodynamic properties and the Meissner effect are also modified accordingly. Finally, we discuss how such a PT -symmetric pairing can emerge from an antisymmetric potential, such as the Dzyloshinskii-Moriya interaction, but with an external bath, or complex potential, among others.
Convex trace functions of several variables
DEFF Research Database (Denmark)
Hansen, Frank
2002-01-01
We prove that the function (x1,...,xk)¿Tr(f(x1,...,xk)), defined on k-tuples of symmetric matrices of order (n1,...,nk) in the domain of f, is convex for any convex function f of k variables. The matrix f(x1,...,xk) is defined by the functional calculus for functions of several variables, and it ...
Witsenburg, C P J; Rosendaal, F R; Middeldorp, J M; Van der Meer, F J M; Scherjon, S A
2005-01-01
Recently, acquired as well as genetic prothrombotic factors are associated with thrombotic events. These factors have also been related to conditions of uteroplacental insufficiency such as pre-eclampsia, HELLP syndrome and severe intrauterine growth restriction (IUGR). The aim of this study was to determine whether elevated factor VIII levels are associated with uteroplacental insufficiency, in particular pre-eclampsia, HELLP syndrome or pregnancy-induced hypertension and intrauterine growth retardation. Plasma samples of 75 women with a history of pregnancy complicated by pre-eclampsia, HELLP syndrome, pregnancy induced hypertension or intrauterine growth restriction were tested for factor VIII:C (FVIII:C) levels at a minimum of 10 weeks post-partum. Laboratory results were compared to factor VIII:C levels found in a healthy control group of 272 women. Mean factor VIII:C levels were similar at 123 IU/dl in both the patient group and the controls. In a logistic regression model, after adjusting for age and blood group, no effect of factor VIII:C levels on the risk of pregnancy complications was observed, with the exception of IUGR with (OR 2.9, CI 1.0-8.7) or without hypertension (OR 2.0, CI 0.7-6.4). If the elevated level of factor VIII would be the sole factor responsible for the increased risk observed, one would expect to find an effect of blood group on risk as well (blood group being an important determinant of FVIII:C). While no such effect could be shown a causal relationship between elevated levels of factor VIII and conditions of uteroplacental insufficiency such as pre-eclampsia, HELLP syndrome, pregnancy-induced hypertension and IUGR is not very likely.
Decomposition of a symmetric second-order tensor
Heras, José A.
2018-05-01
In the three-dimensional space there are different definitions for the dot and cross products of a vector with a second-order tensor. In this paper we show how these products can uniquely be defined for the case of symmetric tensors. We then decompose a symmetric second-order tensor into its ‘dot’ part, which involves the dot product, and the ‘cross’ part, which involves the cross product. For some physical applications, this decomposition can be interpreted as one in which the dot part identifies with the ‘parallel’ part of the tensor and the cross part identifies with the ‘perpendicular’ part. This decomposition of a symmetric second-order tensor may be suitable for undergraduate courses of vector calculus, mechanics and electrodynamics.
Solitons in PT-symmetric potential with competing nonlinearity
International Nuclear Information System (INIS)
Khare, Avinash; Al-Marzoug, S.M.; Bahlouli, Hocine
2012-01-01
We investigate the effect of competing nonlinearities on beam dynamics in PT-symmetric potentials. In particular, we consider the stationary nonlinear Schrödinger equation (NLSE) in one dimension with competing cubic and generalized nonlinearity in the presence of a PT-symmetric potential. Closed form solutions for localized states are obtained. These solitons are shown to be stable over a wide range of potential parameters. The transverse power flow associated with these complex solitons is also examined. -- Highlights: ► Effect of competing nonlinearities on beam dynamics in PT-symmetric potentials. ► Closed form solutions for localized states are. ► The transverse power flow associated with these complex solitons is also examined.
Nilpotent orbits in real symmetric pairs and stationary black holes
Energy Technology Data Exchange (ETDEWEB)
Dietrich, Heiko [School of Mathematical Sciences, Monash University, VIC (Australia); De Graaf, Willem A. [Department of Mathematics, University of Trento, Povo (Italy); Ruggeri, Daniele [Universita di Torino, Dipartimento di Fisica (Italy); INFN, Sezione di Torino (Italy); Trigiante, Mario [DISAT, Politecnico di Torino (Italy)
2017-02-15
In the study of stationary solutions in extended supergravities with symmetric scalar manifolds, the nilpotent orbits of a real symmetric pair play an important role. In this paper we discuss two approaches to determine the nilpotent orbits of a real symmetric pair. We apply our methods to an explicit example, and thereby classify the nilpotent orbits of (SL{sub 2}(R)){sup 4} acting on the fourth tensor power of the natural 2-dimensional SL{sub 2}(R)-module. This makes it possible to classify all stationary solutions of the so-called STU-supergravity model. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Tourist Demand Reactions: Symmetric or Asymmetric across the Business Cycle?
Bronner, Fred; de Hoog, Robert
2017-09-01
Economizing and spending priorities on different types of vacations are investigated during two periods: an economic downturn and returning prosperity. Two nation-wide samples of vacationers are used: one during a downturn, the other one at the start of the recovery period. Through comparing the results, conclusions can be drawn about symmetric or asymmetric tourist demand across the business cycle. The main summer holiday has an asymmetric profile: being fairly crisis-resistant during a recession and showing considerable growth during an expansion. This does not apply to short vacations and day trips, each having a symmetric profile: during a recession they experience substantial reductions and during expansion comparable growth. So when talking about tourist demand in general , one cannot say that it is symmetric or asymmetric across the business cycle: it depends on the type of vacation. Differences in tourist demand are best explained by the role of Quality-of-Life for vacationers.
Symmetric spaces and the Kashiwara-Vergne method
Rouvière, François
2014-01-01
Gathering and updating results scattered in journal articles over thirty years, this self-contained monograph gives a comprehensive introduction to the subject. Its goal is to: - motivate and explain the method for general Lie groups, reducing the proof of deep results in invariant analysis to the verification of two formal Lie bracket identities related to the Campbell-Hausdorff formula (the "Kashiwara-Vergne conjecture"); - give a detailed proof of the conjecture for quadratic and solvable Lie algebras, which is relatively elementary; - extend the method to symmetric spaces; here an obstruction appears, embodied in a single remarkable object called an "e-function"; - explain the role of this function in invariant analysis on symmetric spaces, its relation to invariant differential operators, mean value operators and spherical functions; - give an explicit e-function for rank one spaces (the hyperbolic spaces); - construct an e-function for general symmetric spaces, in the spirit of Kashiwara and Vergne's or...
Rings with involution whose symmetric elements are central
Directory of Open Access Journals (Sweden)
Taw Pin Lim
1980-01-01
Full Text Available In a ring R with involution whose symmetric elements S are central, the skew-symmetric elements K form a Lie algebra over the commutative ring S. The classification of such rings which are 2-torsion free is equivalent to the classification of Lie algebras K over S equipped with a bilinear form f that is symmetric, invariant and satisfies [[x,y],z]=f(y,zx−f(z,xy. If S is a field of char ≠2, f≠0 and dimK>1 then K is a semisimple Lie algebra if and only if f is nondegenerate. Moreover, the derived algebra K′ is either the pure quaternions over S or a direct sum of mutually orthogonal abelian Lie ideals of dim≤2.
Kinetic-energy distribution for symmetric fission of 236U
International Nuclear Information System (INIS)
Brissot, R.; Bocquet, J.P.; Ristori, C.; Crancon, J.; Guet, C.R.; Nifenecker, H.A.; Montoya, M.
1980-01-01
Fission fragment kinetic-energy distributions have been measured at the Grenoble high-flux reactor with the Lohengrin facility. Spurious events were eliminated in the symmetric region by a coherence test based on a time-of-flight measurement of fragment velocities. A Monte-Carlo calculation is then performed to correct the experimental data for neutron evaporation. The difference between the most probable kinetic energy in symmetric fission and the fission in which the heavy fragment is 'magic' (Zsub(H)=50) is found to be approximately =30 MeV. The results suggest that for the symmetric case the total excitation energy available at scission is shared equally among the fragments. (author)
The discrete dynamics of symmetric competition in the plane.
Jiang, H; Rogers, T D
1987-01-01
We consider the generalized Lotka-Volterra two-species system xn + 1 = xn exp(r1(1 - xn) - s1yn) yn + 1 = yn exp(r2(1 - yn) - s2xn) originally proposed by R. M. May as a model for competitive interaction. In the symmetric case that r1 = r2 and s1 = s2, a region of ultimate confinement is found and the dynamics therein are described in some detail. The bifurcations of periodic points of low period are studied, and a cascade of period-doubling bifurcations is indicated. Within the confinement region, a parameter region is determined for the stable Hopf bifurcation of a pair of symmetrically placed period-two points, which imposes a second component of oscillation near the stable cycles. It is suggested that the symmetric competitive model contains much of the dynamical complexity to be expected in any discrete two-dimensional competitive model.
Bound states for non-symmetric evolution Schroedinger potentials
Energy Technology Data Exchange (ETDEWEB)
Corona, Gulmaro Corona [Area de Analisis Matematico y sus Aplicaciones, Universidad Autonoma Metropolitana-Azcapotalco, Atzcapotzalco, DF (Mexico)). E-mail: ccg@correo.azc.uam.mx
2001-09-14
We consider the spectral problem associated with the evolution Schroedinger equation, (D{sup 2}+ k{sup 2}){phi}=u{phi}, where u is a matrix-square-valued function, with entries in the Schwartz class defined on the real line. The solution {phi}, called the wavefunction, consists of a function of one real variable, matrix-square-valued with entries in the Schwartz class. This problem has been dealt for symmetric potentials u. We found for the present case that the bound states are localized similarly to the scalar and symmetric cases, but by the zeroes of an analytic matrix-valued function. If we add an extra condition to the potential u, we can determine these states by an analytic scalar function. We do this by generalizing the scalar and symmetric cases but without using the fact that the Wronskian of a pair of wavefunction is constant. (author)
Solution of generalized shifted linear systems with complex symmetric matrices
International Nuclear Information System (INIS)
Sogabe, Tomohiro; Hoshi, Takeo; Zhang, Shao-Liang; Fujiwara, Takeo
2012-01-01
We develop the shifted COCG method [R. Takayama, T. Hoshi, T. Sogabe, S.-L. Zhang, T. Fujiwara, Linear algebraic calculation of Green’s function for large-scale electronic structure theory, Phys. Rev. B 73 (165108) (2006) 1–9] and the shifted WQMR method [T. Sogabe, T. Hoshi, S.-L. Zhang, T. Fujiwara, On a weighted quasi-residual minimization strategy of the QMR method for solving complex symmetric shifted linear systems, Electron. Trans. Numer. Anal. 31 (2008) 126–140] for solving generalized shifted linear systems with complex symmetric matrices that arise from the electronic structure theory. The complex symmetric Lanczos process with a suitable bilinear form plays an important role in the development of the methods. The numerical examples indicate that the methods are highly attractive when the inner linear systems can efficiently be solved.
Parallel coupling of symmetric and asymmetric exclusion processes
International Nuclear Information System (INIS)
Tsekouras, K; Kolomeisky, A B
2008-01-01
A system consisting of two parallel coupled channels where particles in one of them follow the rules of totally asymmetric exclusion processes (TASEP) and in another one move as in symmetric simple exclusion processes (SSEP) is investigated theoretically. Particles interact with each other via hard-core exclusion potential, and in the asymmetric channel they can only hop in one direction, while on the symmetric lattice particles jump in both directions with equal probabilities. Inter-channel transitions are also allowed at every site of both lattices. Stationary state properties of the system are solved exactly in the limit of strong couplings between the channels. It is shown that strong symmetric couplings between totally asymmetric and symmetric channels lead to an effective partially asymmetric simple exclusion process (PASEP) and properties of both channels become almost identical. However, strong asymmetric couplings between symmetric and asymmetric channels yield an effective TASEP with nonzero particle flux in the asymmetric channel and zero flux on the symmetric lattice. For intermediate strength of couplings between the lattices a vertical-cluster mean-field method is developed. This approximate approach treats exactly particle dynamics during the vertical transitions between the channels and it neglects the correlations along the channels. Our calculations show that in all cases there are three stationary phases defined by particle dynamics at entrances, at exits or in the bulk of the system, while phase boundaries depend on the strength and symmetry of couplings between the channels. Extensive Monte Carlo computer simulations strongly support our theoretical predictions. Theoretical calculations and computer simulations predict that inter-channel couplings have a strong effect on stationary properties. It is also argued that our results might be relevant for understanding multi-particle dynamics of motor proteins
Symmetric vs. asymmetric stem cell divisions: an adaptation against cancer?
Directory of Open Access Journals (Sweden)
Leili Shahriyari
Full Text Available Traditionally, it has been held that a central characteristic of stem cells is their ability to divide asymmetrically. Recent advances in inducible genetic labeling provided ample evidence that symmetric stem cell divisions play an important role in adult mammalian homeostasis. It is well understood that the two types of cell divisions differ in terms of the stem cells' flexibility to expand when needed. On the contrary, the implications of symmetric and asymmetric divisions for mutation accumulation are still poorly understood. In this paper we study a stochastic model of a renewing tissue, and address the optimization problem of tissue architecture in the context of mutant production. Specifically, we study the process of tumor suppressor gene inactivation which usually takes place as a consequence of two "hits", and which is one of the most common patterns in carcinogenesis. We compare and contrast symmetric and asymmetric (and mixed stem cell divisions, and focus on the rate at which double-hit mutants are generated. It turns out that symmetrically-dividing cells generate such mutants at a rate which is significantly lower than that of asymmetrically-dividing cells. This result holds whether single-hit (intermediate mutants are disadvantageous, neutral, or advantageous. It is also independent on whether the carcinogenic double-hit mutants are produced only among the stem cells or also among more specialized cells. We argue that symmetric stem cell divisions in mammals could be an adaptation which helps delay the onset of cancers. We further investigate the question of the optimal fraction of stem cells in the tissue, and quantify the contribution of non-stem cells in mutant production. Our work provides a hypothesis to explain the observation that in mammalian cells, symmetric patterns of stem cell division seem to be very common.
Some curvature properties of quarter symmetric metric connections
International Nuclear Information System (INIS)
Rastogi, S.C.
1986-08-01
A linear connection Γ ji h with torsion tensor T j h P i -T i h P j , where T j h is an arbitrary (1,1) tensor field and P i is a 1-form, has been called a quarter-symmetric connection by Golab. Some properties of such connections have been studied by Rastogi, Mishra and Pandey, and Yano and Imai. In this paper based on the curvature tensor of quarter-symmetric metric connection we define a tensor analogous to conformal curvature tensor and study some properties of such a tensor. (author)
Symmetric bends how to join two lengths of cord
Miles, Roger E
1995-01-01
A bend is a knot securely joining together two lengths of cord (or string or rope), thereby yielding a single longer length. There are many possible different bends, and a natural question that has probably occurred to many is: "Is there a 'best' bend and, if so, what is it?"Most of the well-known bends happen to be symmetric - that is, the two constituent cords within the bend have the same geometric shape and size, and interrelationship with the other. Such 'symmetric bends' have great beauty, especially when the two cords bear different colours. Moreover, they have the practical advantage o
Norm estimates of complex symmetric operators applied to quantum systems
International Nuclear Information System (INIS)
Prodan, Emil; Garcia, Stephan R; Putinar, Mihai
2006-01-01
This paper communicates recent results in the theory of complex symmetric operators and shows, through two non-trivial examples, their potential usefulness in the study of Schroedinger operators. In particular, we propose a formula for computing the norm of a compact complex symmetric operator. This observation is applied to two concrete problems related to quantum mechanical systems. First, we give sharp estimates on the exponential decay of the resolvent and the single-particle density matrix for Schroedinger operators with spectral gaps. Second, we provide new ways of evaluating the resolvent norm for Schroedinger operators appearing in the complex scaling theory of resonances
Exploring plane-symmetric solutions in f(R) gravity
Energy Technology Data Exchange (ETDEWEB)
Shamir, M. F., E-mail: farasat.shamir@nu.edu.pk [National University of Computer and Emerging Sciences, Department of Sciences and Humanities (Pakistan)
2016-02-15
The modified theories of gravity, especially the f(R) gravity, have attracted much attention in the last decade. This paper is devoted to exploring plane-symmetric solutions in the context of metric f(R) gravity. We extend the work on static plane-symmetric vacuum solutions in f(R) gravity already available in the literature [1, 2]. The modified field equations are solved using the assumptions of both constant and nonconstant scalar curvature. Some well-known solutions are recovered with power-law and logarithmic forms of f(R) models.
Characterization of Generalized Young Measures Generated by Symmetric Gradients
De Philippis, Guido; Rindler, Filip
2017-06-01
This work establishes a characterization theorem for (generalized) Young measures generated by symmetric derivatives of functions of bounded deformation (BD) in the spirit of the classical Kinderlehrer-Pedregal theorem. Our result places such Young measures in duality with symmetric-quasiconvex functions with linear growth. The "local" proof strategy combines blow-up arguments with the singular structure theorem in BD (the analogue of Alberti's rank-one theorem in BV), which was recently proved by the authors. As an application of our characterization theorem we show how an atomic part in a BD-Young measure can be split off in generating sequences.
Integrability and symmetric spaces. II- The coset spaces
International Nuclear Information System (INIS)
Ferreira, L.A.
1987-01-01
It shown that a sufficient condition for a model describing the motion of a particle on a coset space to possess a fundamental Poisson bracket relation, and consequently charges involution, is that it must be a symmetric space. The conditions a hamiltonian, or any function of the canonical variables, has to satisfy in order to commute with these charges are studied. It is shown that, for the case of non compact symmetric space, these conditions lead to an algebraic structure which plays an important role in the construction of conserved quantities. (author) [pt
Color-symmetric superconductivity in a phenomenological QCD model
DEFF Research Database (Denmark)
Bohr, Henrik; Providencia, C.; Providencia, J. da
2009-01-01
In this paper, we construct a theory of the NJL type where superconductivity is present, and yet the superconducting state remains, in the average, color symmetric. This shows that the present approach to color superconductivity is consistent with color singletness. Indeed, quarks are free...... in the deconfined phase, but the deconfined phase itself is believed to be a color singlet. The usual description of the color superconducting state violates color singletness. On the other hand, the color superconducting state here proposed is color symmetric in the sense that an arbitrary color rotation leads...
(Anti)symmetric multivariate exponential functions and corresponding Fourier transforms
International Nuclear Information System (INIS)
Klimyk, A U; Patera, J
2007-01-01
We define and study symmetrized and antisymmetrized multivariate exponential functions. They are defined as determinants and antideterminants of matrices whose entries are exponential functions of one variable. These functions are eigenfunctions of the Laplace operator on the corresponding fundamental domains satisfying certain boundary conditions. To symmetric and antisymmetric multivariate exponential functions there correspond Fourier transforms. There are three types of such Fourier transforms: expansions into the corresponding Fourier series, integral Fourier transforms and multivariate finite Fourier transforms. Eigenfunctions of the integral Fourier transforms are found
Positive projections of symmetric matrices and Jordan algebras
DEFF Research Database (Denmark)
Fuglede, Bent; Jensen, Søren Tolver
2013-01-01
An elementary proof is given that the projection from the space of all symmetric p×p matrices onto a linear subspace is positive if and only if the subspace is a Jordan algebra. This solves a problem in a statistical model.......An elementary proof is given that the projection from the space of all symmetric p×p matrices onto a linear subspace is positive if and only if the subspace is a Jordan algebra. This solves a problem in a statistical model....
Algorithms for sparse, symmetric, definite quadratic lambda-matrix eigenproblems
International Nuclear Information System (INIS)
Scott, D.S.; Ward, R.C.
1981-01-01
Methods are presented for computing eigenpairs of the quadratic lambda-matrix, M lambda 2 + C lambda + K, where M, C, and K are large and sparse, and have special symmetry-type properties. These properties are sufficient to insure that all the eigenvalues are real and that theory analogous to the standard symmetric eigenproblem exists. The methods employ some standard techniques such as partial tri-diagonalization via the Lanczos Method and subsequent eigenpair calculation, shift-and- invert strategy and subspace iteration. The methods also employ some new techniques such as Rayleigh-Ritz quadratic roots and the inertia of symmetric, definite, quadratic lambda-matrices
Determination of symmetrical index for 3H in river waters
International Nuclear Information System (INIS)
Jankovic, M.; Todorovic, D.; Jankovic, B.; Nikolic, J.; Sarap, N.
2011-01-01
The paper presents the results of determining the symmetric index, which describes the magnitude of the tritium content changes with time, for samples of Sava and Danube river waters and Mlaka creek water. The results cover the period from 2003 to 2008. It was shown that the value of the symmetric index is the highest for Mlaka samples, which is in accordance with the fact that in these samples the highest concentration of tritium was found in comparison with samples of the Sava and Danube. [sr
Flat synchronizations in spherically symmetric space-times
International Nuclear Information System (INIS)
Herrero, Alicia; Morales-Lladosa, Juan Antonio
2010-01-01
It is well known that the Schwarzschild space-time admits a spacelike slicing by flat instants and that the metric is regular at the horizon in the associated adapted coordinates (Painleve-Gullstrand metric form). We consider this type of flat slicings in an arbitrary spherically symmetric space-time. The condition ensuring its existence is analyzed, and then, we prove that, for any spherically symmetric flat slicing, the densities of the Weinberg momenta vanish. Finally, we deduce the Schwarzschild solution in the extended Painleve-Gullstrand-LemaItre metric form by considering the coordinate decomposition of the vacuum Einstein equations with respect to a flat spacelike slicing.
Time-symmetric integration in astrophysics
Hernandez, David M.; Bertschinger, Edmund
2018-04-01
Calculating the long-term solution of ordinary differential equations, such as those of the N-body problem, is central to understanding a wide range of dynamics in astrophysics, from galaxy formation to planetary chaos. Because generally no analytic solution exists to these equations, researchers rely on numerical methods that are prone to various errors. In an effort to mitigate these errors, powerful symplectic integrators have been employed. But symplectic integrators can be severely limited because they are not compatible with adaptive stepping and thus they have difficulty in accommodating changing time and length scales. A promising alternative is time-reversible integration, which can handle adaptive time-stepping, but the errors due to time-reversible integration in astrophysics are less understood. The goal of this work is to study analytically and numerically the errors caused by time-reversible integration, with and without adaptive stepping. We derive the modified differential equations of these integrators to perform the error analysis. As an example, we consider the trapezoidal rule, a reversible non-symplectic integrator, and show that it gives secular energy error increase for a pendulum problem and for a Hénon-Heiles orbit. We conclude that using reversible integration does not guarantee good energy conservation and that, when possible, use of symplectic integrators is favoured. We also show that time-symmetry and time-reversibility are properties that are distinct for an integrator.
International Nuclear Information System (INIS)
Wiliardy, Abednego; Gunara, Bobby Eka
2016-01-01
An n dimensional flat manifold N is embedded into an n +1 dimensional stationary manifold M. The metric of M is derived from a general form of stationary manifold. By taking several assumption, such as 1) the ambient manifold M to be maximally symmetric space and satisfying a pure gauge condition, and 2) the submanifold is taken to be flat, then we find the solution that satisfies Ricci scalar of N . Moreover, we determine whether the solution is compatible with the Ricci and Riemann tensor of manifold N depending on the dimension. (paper)
THE COVARIATION FUNCTION FOR SYMMETRIC &ALPHA;-STABLE RANDOM VARIABLES WITH FINITE FIRST MOMENTS
Directory of Open Access Journals (Sweden)
Dedi Rosadi
2012-05-01
Full Text Available In this paper, we discuss a generalized dependence measure which is designed to measure dependence of two symmetric α-stable random variables with finite mean(1<α<=2 and contains the covariance function as the special case (when α=2. Weshortly discuss some basic properties of the function and consider several methods to estimate the function and further investigate the numerical properties of the estimatorusing the simulated data. We show how to apply this function to measure dependence of some stock returns on the composite index LQ45 in Indonesia Stock Exchange.
Studies on radiation symmetrization in heavy-ion driven hohlraum targets
International Nuclear Information System (INIS)
Temporal, M.; Atzeni, S.
1993-01-01
Radiation symmetrization within spherical, ellipsoidal and cylindral hohlraum targets for heavy ion inertial confinement fusion (ICF) is studied by means of a 3-D numerical, static model, in which realistic assumptions are made concerning the geometry of the system and, particularly, of the radiation converters. Among the systems so far studied, only spherical hohlraums with six converters achieve the illumination symmetry of the fusion capsule considered necessary for ICF applications. A parametric study of cylindrical hohlraums enlightens the effect of several parameter changes, and suggests directions for further studies, aiming at the design of two-converter targets
Bilaterally symmetric Fourier approximations of the skull outlines of ...
Indian Academy of Sciences (India)
Present work illustrates a scheme of quantitative description of the shape of the skull outlines of temnospondyl amphibians using bilaterally symmetric closed Fourier curves. Some special points have been identified on the Fourier fits of the skull outlines, which are the local maxima, or minima of the distances from the ...
PEO nanocomposite polymer electrolyte for solid state symmetric
Indian Academy of Sciences (India)
Physical and electrochemical properties of polyethylene oxide (PEO)-based nanocomposite solid polymer electrolytes (NPEs) were investigated for symmetric capacitor applications. Nanosize fillers, i.e., Al2O3 and SiO2 incorporated polymer electrolyte exhibited higher ionic conductivity than those with filler-free composites ...
Symmetric approximations of the Navier-Stokes equations
International Nuclear Information System (INIS)
Kobel'kov, G M
2002-01-01
A new method for the symmetric approximation of the non-stationary Navier-Stokes equations by a Cauchy-Kovalevskaya-type system is proposed. Properties of the modified problem are studied. In particular, the convergence as ε→0 of the solutions of the modified problem to the solutions of the original problem on an infinite interval is established
Duality, phase structures, and dilemmas in symmetric quantum games
International Nuclear Information System (INIS)
Ichikawa, Tsubasa; Tsutsui, Izumi
2007-01-01
Symmetric quantum games for 2-player, 2-qubit strategies are analyzed in detail by using a scheme in which all pure states in the 2-qubit Hilbert space are utilized for strategies. We consider two different types of symmetric games exemplified by the familiar games, the Battle of the Sexes (BoS) and the Prisoners' Dilemma (PD). These two types of symmetric games are shown to be related by a duality map, which ensures that they share common phase structures with respect to the equilibria of the strategies. We find eight distinct phase structures possible for the symmetric games, which are determined by the classical payoff matrices from which the quantum games are defined. We also discuss the possibility of resolving the dilemmas in the classical BoS, PD, and the Stag Hunt (SH) game based on the phase structures obtained in the quantum games. It is observed that quantization cannot resolve the dilemma fully for the BoS, while it generically can for the PD and SH if appropriate correlations for the strategies of the players are provided
SUSY formalism for the symmetric double well potential
Indian Academy of Sciences (India)
Using first- and second-order supersymmetric Darboüx formalism and starting with symmetric double well potential barrier we have obtained a class of exactly solvable potentials subject to moving boundary condition. The eigenstates are also obtained by the same technique.
Initial value formulation for the spherically symmetric dust solution
International Nuclear Information System (INIS)
Liu, H.
1990-01-01
An initial value formulation for the dust solution with spherical symmetry is given explicitly in which the initial distributions of dust and its velocity on an initial surface are chosen to be the initial data. As special cases, the Friedmann universe, the Schwarzschild solution in comoving coordinates, and a spherically symmetric and radially inhomogeneous cosmological model are derived
Coupled dilaton and electromagnetic field in cylindrically symmetric ...
Indian Academy of Sciences (India)
An exact solution is obtained for coupled dilaton and electromagnetic ﬁeld in a cylindrically symmetric spacetime where an axial magnetic ﬁeld as well as a radial electric ﬁeld both are present. Depending on the choice of the arbitrary constants our solution reduces either to dilatonic gravity with pure electric ﬁeld or to that ...
PT-Symmetric Waveguides and the Lack of Variational Techniques
Czech Academy of Sciences Publication Activity Database
Krejčiřík, David
2012-01-01
Roč. 73, č. 1 (2012), s. 1-2 ISSN 0378-620X Institutional support: RVO:61389005 Keywords : Robin Laplacian * non-self-adjoint boundary conditions * complex symmetric operator * PT-symmetry * waveguides * discrete and essential spectra Subject RIV: BA - General Mathematics Impact factor: 0.713, year: 2012
Confining but chirally symmetric dense and cold matter
International Nuclear Information System (INIS)
Glozman, L. Ya.
2012-01-01
The possibility for existence of cold, dense chirally symmetric matter with confinement is reviewed. The answer to this question crucially depends on the mechanism of mass generation in QCD and interconnection of confinement and chiral symmetry breaking. This question can be clarified from spectroscopy of hadrons and their axial properties. Almost systematical parity doubling of highly excited hadrons suggests that their mass is not related to chiral symmetry breaking in the vacuum and is approximately chirally symmetric. Then there is a possibility for existence of confining but chirally symmetric matter. We clarify a possible mechanism underlying such a phase at low temperatures and large density. Namely, at large density the Pauli blocking prevents the gap equation to generate a solution with broken chiral symmetry. However, the chirally symmetric part of the quark Green function as well as all color non-singlet quantities are still infrared divergent, meaning that the system is with confinement. A possible phase transition to such a matter is most probably of the first order. This is because there are no chiral partners to the lowest lying hadrons.
Technical report: Electric field in not completely symmetric systems
International Nuclear Information System (INIS)
Vila, F.
1994-08-01
In this paper it is studied theoretically the electric field in the not completely symmetric system earthed metallic sphere-uniformly charged dielectric plan, for sphere surface points situated in the plan that contains sphere's center and vertical symmetry axe of dielectric plan. (author). 11 refs, 1 fig
Symmetrical waveguide devices fabricated by direct UV writing
DEFF Research Database (Denmark)
Færch, Kjartan Ullitz; Svalgaard, Mikael
2002-01-01
Power splitters and directional couplers fabricated by direct UV writing in index matched silica-on-silicon samples can suffer from an asymmetrical device performance, even though the UV writing is carried out in a symmetrical fashion. This effect originates from a reduced photosensitivity...
On the axially symmetric equilibrium of a magnetically confined plasma
International Nuclear Information System (INIS)
Lehnert, B.
1975-01-01
The axially symmetric equilibrium of a magnetically confined plasma is reconsidered, with the special purpose of studying high-beta schemes with a purely poloidal magnetic field. A number of special solutions of the pressure and magnetic flux functions are shown to exist, the obtained results may form starting-points in a further analysis of physically relevant configurations. (Auth.)
Symmetric structures of coherent states in superfluid helium-4
International Nuclear Information System (INIS)
Ahmad, M.
1981-02-01
Coherent States in superfluid helium-4 are discussed and symmetric structures are assigned to these states. Discrete and continuous series functions are exhibited for such states. Coherent State structure has been assigned to oscillating condensed bosons and their inter-relations and their effects on the superfluid system are analysed. (author)
Spectra of PT -symmetric Hamiltonians on tobogganic contours
Indian Academy of Sciences (India)
The term PT -symmetric quantum mechanics, although defined to be of a much broader use, was coined in tight connection with C. Bender's analysis of one- ... on the other hand, the other members of the family were strange Hamiltonians with imaginary potentials which do not appear physical at all. The aim of the.
Symmetrical and asymmetrical growth restriction in preterm-born children
Bocca-Tjeertes, Inger; Bos, Arend; Kerstjens, Jorien; de Winter, Andrea; Reijneveld, Sijmen
OBJECTIVE: To determine how symmetric (proportionate; SGR) and asymmetric (disproportionate; AGR) growth restriction influence growth and development in preterms from birth to 4 years. METHODS: This community-based cohort study of 810 children comprised 86 SGR, 61 AGR, and 663 non-growth restricted
Perception of the Symmetrical Patterning of Human Gait by Infants.
Booth, Amy E.; Pinto, Jeannine; Bertenthal, Bennett I.
2002-01-01
Two experiments tested infants' sensitivity to properties of point-light displays of a walker and a runner that were equivalent regarding the phasing of limb movements. Found that 3-, but not 5-month-olds, discriminated these displays. When the symmetrical phase-patterning of the runner display was perturbed by advancing two of its limbs by 25…
Rotationally symmetric numerical solutions to the sine-Gordon equation
DEFF Research Database (Denmark)
Olsen, O. H.; Samuelsen, Mogens Rugholm
1981-01-01
We examine numerically the properties of solutions to the spherically symmetric sine-Gordon equation given an initial profile which coincides with the one-dimensional breather solution and refer to such solutions as ring waves. Expanding ring waves either exhibit a return effect or expand towards...
Symmetrical Womanhood: The Educational Ideology of Activism at Wellesley.
Palmieri, Patricia Ann
1995-01-01
The ideology of higher education for women at Wellesley College in the late 19th and early 20th centuries is discussed in the context of feminism and the women's suffrage movement. "Symmetrical womanhood," a concept emphasizing balance of traditional roles and intellectual and community involvement, was a goal of Wellesley faculty of…
Normalizations of Eisenstein integrals for reductive symmetric spaces
van den Ban, E.P.; Kuit, Job
2017-01-01
We construct minimal Eisenstein integrals for a reductive symmetric space G/H as matrix coefficients of the minimal principal series of G. The Eisenstein integrals thus obtained include those from the \\sigma-minimal principal series. In addition, we obtain related Eisenstein integrals, but with
Analytic families of eigenfunctions on a reductive symmetric space
Ban, E.P. van den; Schlichtkrull, H.
2000-01-01
In harmonic analysis on a reductive symmetric space X an important role is played by families of generalized eigenfunctions for the algebra D (X) of invariant dierential operators. Such families arise for instance as matrix coeÆcients of representations that come in series, such as the (generalized)
Whittaker Vector of Deformed Virasoro Algebra and Macdonald Symmetric Functions
Yanagida, Shintarou
2016-03-01
We give a proof of Awata and Yamada's conjecture for the explicit formula of Whittaker vector of the deformed Virasoro algebra realized in the Fock space. The formula is expressed as a summation over Macdonald symmetric functions with factored coefficients. In the proof, we fully use currents appearing in the Fock representation of Ding-Iohara-Miki quantum algebra.
Plane Symmetric Cosmological Model with Quark and Strange ...
Indian Academy of Sciences (India)
Keywords. f(R,T) theory of gravity—plane symmetric space-time—quark and strange quark matter—constant deceleration parameter. 1. Introduction. Modern astrophysical observations point out that present expansion of the Universe is an accelerated epoch. The most fascinating evidence for this is found in measurements ...
Separator-Integrated, Reversely Connectable Symmetric Lithium-Ion Battery.
Wang, Yuhang; Zeng, Jiren; Cui, Xiaoqi; Zhang, Lijuan; Zheng, Gengfeng
2016-02-24
A separator-integrated, reversely connectable, symmetric lithium-ion battery is developed based on carbon-coated Li3V2(PO4)3 nanoparticles and polyvinylidene fluoride-treated separators. The Li3V2(PO4)3 nanoparticles are synthesized via a facile solution route followed by calcination in Ar/H2 atmosphere. Sucrose solution is used as the carbon source for uniform carbon coating on the Li3V2(PO4)3 nanoparticles. Both the carbon and the polyvinylidene fluoride treatments substantially improve the cycling life of the symmetric battery by preventing the dissolution and shuttle of the electroactive Li3V2(PO4)3. The obtained symmetric full cell exhibits a reversible capacity of ≈ 87 mA h g(-1), good cycling stability, and capacity retention of ≈ 70% after 70 cycles. In addition, this type of symmetric full cell can be operated in both forward and reverse connection modes, without any influence on the cycling of the battery. Furthermore, a new separator integration approach is demonstrated, which enables the direct deposition of electroactive materials for the battery assembly and does not affect the electrochemical performance. A 10-tandem-cell battery assembled without differentiating the electrode polarity exhibits a low thickness of ≈ 4.8 mm and a high output voltage of 20.8 V. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Strong orientational coordinates and orientational order parameters for symmetric objects
International Nuclear Information System (INIS)
Haji-Akbari, Amir; Glotzer, Sharon C
2015-01-01
Recent advancements in the synthesis of anisotropic macromolecules and nanoparticles have spurred an immense interest in theoretical and computational studies of self-assembly. The cornerstone of such studies is the role of shape in self-assembly and in inducing complex order. The problem of identifying different types of order that can emerge in such systems can, however, be challenging. Here, we revisit the problem of quantifying orientational order in systems of building blocks with non-trivial rotational symmetries. We first propose a systematic way of constructing orientational coordinates for such symmetric building blocks. We call the arising tensorial coordinates strong orientational coordinates (SOCs) as they fully and exclusively specify the orientation of a symmetric object. We then use SOCs to describe and quantify local and global orientational order, and spatiotemporal orientational correlations in systems of symmetric building blocks. The SOCs and the orientational order parameters developed in this work are not only useful in performing and analyzing computer simulations of symmetric molecules or particles, but can also be utilized for the efficient storage of rotational information in long trajectories of evolving many-body systems. (paper)
Is PT -symmetric quantum theory false as a fundamental theory?
Czech Academy of Sciences Publication Activity Database
Znojil, Miloslav
2016-01-01
Roč. 56, č. 3 (2016), s. 254-257 ISSN 1210-2709 R&D Projects: GA ČR GA16-22945S Institutional support: RVO:61389005 Keywords : quantum mechanics * PT-symmetric representations of observables * masurement outcomes Subject RIV: BE - Theoretical Physics
A New Symmetrical Unit for Breakwater Armour : First Tests
Salauddin, M.; Broere, A.; Van der Meer, J.W.; Verhagen, H.J.; Bijl, E.
2015-01-01
A new and symmetrical single layer armour unit, the crablock, has been designed in the UAE. One breakwater was reconstructed with crablock, but very limited testing had been performed. Just to become more acquainted with this new unit, pre-competitive research at a university has been performed,
Helically symmetric experiment, (HSX) goals, design and status
International Nuclear Information System (INIS)
Anderson, F.S.B.; Almagri, A.F.; Anderson, D.T.; Matthews, P.G.; Talmadge, J.N.; Shohet, J.L.
1995-01-01
HSX is a quasi-helically symmetric (QHS) stellarator currently under construction at the Torsatron-Stellarator Laboratory of the University of Wisconsin-Madison. This device is unique in its magnetic design in that the magnetic field spectrum possesses only a single dominant (helical) component. This design avoids the large direct orbit losses and the low-collisionality neoclassical losses associated with conventional stellarators. The restoration of symmetry to the confining magnetic field makes the neoclassical confinement in this device analogous to an axisymmetric q=1/3 tokamak. The HSX device has been designed with a clear set of primary physics goals: demonstrate the feasibility of construction of a QHS device, examine single particle confinement of injected ions with regard to magnetic field symmetry breaking, compare density and temperature profiles in this helically symmetric system to those for axisymmetric tokamaks and conventional stellarators, examine electric fields and plasma rotation with edge biasing in relation to L-H transitions in symmetric versus non-symmetric stellarator systems, investigate QHS effects on 1/v regime electron confinement, and examine how greatly-reduced neoclassical electron thermal conductivity compares to the experimental χ e profile. 3 refs., 4 figs., 1 tab
On the random geometry of a symmetric matter antimatter universe
International Nuclear Information System (INIS)
Aldrovandi, R.; Goto, M.
1977-05-01
A statistical analysis is made of the randon geometry of an early symmetric matter-antimatter universe model. Such a model is shown to determine the total number of the largest agglomerations in the universe, as well as of some special configurations. Constraints on the time development of the protoagglomerations are also obtained
On Split Lie Algebras with Symmetric Root Systems
Indian Academy of Sciences (India)
... and any I j a well described ideal of , satisfying [ I j , I k ] = 0 if j ≠ k . Under certain conditions, the simplicity of is characterized and it is shown that is the direct sum of the family of its minimal ideals, each one being a simple split Lie algebra with a symmetric root system and having all its nonzero roots connected.
On split Lie algebras with symmetric root systems
Indian Academy of Sciences (India)
ideal of L, satisfying [Ij ,Ik] = 0 if j = k. Under certain conditions, the simplicity of L is characterized and it is shown that L is the direct sum of the family of its minimal ideals, each one being a simple split Lie algebra with a symmetric root system and having all its nonzero roots connected. Keywords. Infinite dimensional Lie ...
A summary view of the symmetric cosmological model
International Nuclear Information System (INIS)
Aldrovandi, R.
1975-01-01
A brief analysis of cosmological models is done, beginning with the standard model and following with the symmetric model of Omnes. Some attempts have been made for the phase transition in thermal radiation at high temperatures, to the annihilation period and to coalescence. One model with equal amounts of matter and antimatter seems to be reasonable [pt
Compactons in PT-symmetric generalized Korteweg–de Vries ...
Indian Academy of Sciences (India)
... Lecture Workshops · Refresher Courses · Symposia · Live Streaming. Home; Journals; Pramana – Journal of Physics; Volume 73; Issue 2. Compactons in P T -symmetric generalized Korteweg–de Vries equations. Carl M Bender Fred Cooper Avinash Khare Bogdan Mihaila Avadh Saxena. Volume 73 Issue 2 August 2009 ...
New algorithms for the symmetric tridiagonal eigenvalue computation
Energy Technology Data Exchange (ETDEWEB)
Pan, V. [City Univ. of New York, Bronx, NY (United States)]|[International Computer Sciences Institute, Berkeley, CA (United States)
1994-12-31
The author presents new algorithms that accelerate the bisection method for the symmetric eigenvalue problem. The algorithms rely on some new techniques, which include acceleration of Newton`s iteration and can also be further applied to acceleration of some other iterative processes, in particular, of iterative algorithms for approximating polynomial zeros.
Lee, Myoung-Jae; Jung, Young-Dae
2018-05-01
The dispersion properties of surface dust ion-acoustic waves in a self-gravitating magnetized dusty plasma layer with the (r, q) distribution are investigated. The result shows that the wave frequency of the symmetric mode in the plasma layer decreases with an increase in the wave number. It is also shown that the wave frequency of the symmetric mode decreases with an increase in the spectral index r. However, the wave frequency of the anti-symmetric mode increases with an increase in the wave number. It is also found that the anti-symmetric mode wave frequency increases with an increase in the spectral index r. In addition, it is found that the influence of the self-gravitation on the symmetric mode wave frequency decreases with increasing scaled Jeans frequency. Moreover, it is found that the wave frequency of the symmetric mode increases with an increase in the dust charge; however, the anti-symmetric mode shows opposite behavior.
Directory of Open Access Journals (Sweden)
Nuno Ricardo Gonçalves Baptista Pereira
2011-12-01
Full Text Available As lesões vasculares da placenta constituem um grupo de entidades distintas, mas inter-relacionadas, em que se incluem os corioangiomas e a corangiomatose multifocal difusa. O corioangioma é uma lesão nodular expansiva com incidência de cerca de 1%. A corangiomatose multifocal difusa é rara (0,2% e predominante em placentas em idade gestacional inferior a 32 semanas. Os autores apresentam um caso de gestação gemelar monocoriônica/biamniótica, no qual um dos fetos, à 26ª semana de gestação, apresentou quadro de restrição de crescimento intrauterino, hidropisia e anemia associado à formação tumoral da placenta com vascularização aumentada verificada pela doplervelocimetria. O estudo anatomopatológico da placenta permitiu o diagnóstico de corangiomatose multifocal difusa. Este raro caso de corioangiomatose multifocal difusa com forma de apresentação pré-natal mimetizando a de um corioangioma comprova que a detecção ultrassonográfica de um tumor da placenta com vascularização aumentada deve suscitar outras hipótese diagnóstica, além do corioangioma.Placenta vascular lesions are a group of distinct yet related entities that include chorangiomas and diffuse multifocal chorangiomatosis. Chorangioma is an expansive nodular lesion with an incidence of about 1%. Diffuse multifocal chorangiomatosis is rare (0.2% and mostly seen in placentas before the 32nd gestational week. The authors present a case of a monochorionic/biamniotic twin pregnancy, in which, at the 26th gestational week, one fetus developed intrauterine growth restriction (IUGR, hydrops, and anemia associated with a tumor of the placenta with increased vascularization in the Doppler study. Pathological examination of the placenta diagnosed diffuse multifocal chorangiomatosis. This rare case report of diffuse multifocal chorangiomatosis with prenatal manifestations resembling those of a chorangioma proves that prenatal ultrasound detection of a placenta tumor
Hati, Chandan; Patra, Sudhanwa; Pritimita, Prativa; Sarkar, Utpal
2018-03-01
In this review, we present several variants of left-right symmetric models in the context of neutrino masses and leptogenesis. In particular, we discuss various low scale seesaw mechanisms like linear seesaw, inverse seesaw, extended seesaw and their implications to lepton number violating process like neutrinoless double beta decay. We also visit an alternative framework of left-right models with the inclusion of vector-like fermions to analyze the aspects of universal seesaw. The symmetry breaking of left-right symmetric model around few TeV scale predicts the existence of massive right-handed gauge bosons W_R and Z_R which might be detected at the LHC in near future. If such signals are detected at the LHC that can have severe implications for leptogenesis, a mechanism to explain the observed baryon asymmetry of the Universe. We review the implications of TeV scale left-right symmetry breaking for leptogenesis.
On the pseudo-norm in some PT-symmetric potentials
International Nuclear Information System (INIS)
Levai, G.
2005-01-01
Complete text of publication follows. PT-symmetric quantum mechanical systems possess non-hermitian Hamiltonian, still they have some characteristics similar to hermitian problems. The most notable of these is their discrete energy spectrum, which can be partly or completely real. These systems are invariant under the simultaneous action of the P space and T time inversion operations. Perhaps the simplest PT-symmetric Hamiltonian contains a one-dimensional Schroedinger operator with a complex potential satisfying the V*(-x) = V (x) relation. Another typical feature PT-symmetric systems have in common with hermitian problems is that their basis states form an orthogonal set provided that the inner product is redefined as (ψ φ)PT ≡ (ψ Pφ). However, the norm defined by this inner product, the pseudo-norm turned out to possess indefinite sign, and this raised the question of the probabilistic interpretation of PT-symmetric systems. This problem was later put into a more general context when it was found that PT symmetry is a special case of pseudo-hermiticity, and this explains most of the peculiar features of PT-symmetric systems. There have been several attempts to link PT-symmetric, and in general, pseudo- hermitian systems with equivalent hermitian ones, and the sign of the pseudo-norm was found to play an important role in this respect. It is thus essential to evaluate the pseudo- norm for various potentials, especially considering the fact that there are some inconsistencies in the available results. Numerical studies indicated that the sign of the pseudo-norm typically alternates according to the n principal quantum number as (-1) n , and this was later proven for a class of potentials that are written in a polynomial form of ix. However, some potentials of other type did not fit into this line: this was the case for the Scarf II potential, the most well-known exactly solvable PT-symmetric potential. In contrast with the other examples, this potential is
PT-symmetric planar devices for field transformation and imaging
International Nuclear Information System (INIS)
Valagiannopoulos, C A; Monticone, F; Alù, A
2016-01-01
The powerful tools of transformation optics (TO) allow an effective distortion of a region of space by carefully engineering the material inhomogeneity and anisotropy, and have been successfully applied in recent years to control electromagnetic fields in many different scenarios, e.g., to realize invisibility cloaks and planar lenses. For various field transformations, it is not necessary to use volumetric inhomogeneous materials, and suitably designed ultrathin metasurfaces with tailored spatial or spectral responses may be able to realize similar functionalities within smaller footprints and more robust mechanisms. Here, inspired by the concept of metamaterial TO lenses, we discuss field transformations enabled by parity-time (PT) symmetric metasurfaces, which can emulate negative refraction. We first analyze a simple realization based on homogeneous and local metasurfaces to achieve negative refraction and imaging, and we then extend our results to arbitrary PT-symmetric two-port networks to realize aberration-free planar imaging. (paper)
Nonstandard jump functions for radically symmetric shock waves
International Nuclear Information System (INIS)
Baty, Roy S.; Tucker, Don H.; Stanescu, Dan
2008-01-01
Nonstandard analysis is applied to derive generalized jump functions for radially symmetric, one-dimensional, magnetogasdynamic shock waves. It is assumed that the shock wave jumps occur on infinitesimal intervals and the jump functions for the physical parameters occur smoothly across these intervals. Locally integrable predistributions of the Heaviside function are used to model the flow variables across a shock wave. The equations of motion expressed in nonconservative form are then applied to derive unambiguous relationships between the jump functions for the physical parameters for two families of self-similar flows. It is shown that the microstructures for these families of radially symmetric, magnetogasdynamic shock waves coincide in a nonstandard sense for a specified density jump function.
Random matrix ensembles for PT-symmetric systems
International Nuclear Information System (INIS)
Graefe, Eva-Maria; Mudute-Ndumbe, Steve; Taylor, Matthew
2015-01-01
Recently much effort has been made towards the introduction of non-Hermitian random matrix models respecting PT-symmetry. Here we show that there is a one-to-one correspondence between complex PT-symmetric matrices and split-complex and split-quaternionic versions of Hermitian matrices. We introduce two new random matrix ensembles of (a) Gaussian split-complex Hermitian; and (b) Gaussian split-quaternionic Hermitian matrices, of arbitrary sizes. We conjecture that these ensembles represent universality classes for PT-symmetric matrices. For the case of 2 × 2 matrices we derive analytic expressions for the joint probability distributions of the eigenvalues, the one-level densities and the level spacings in the case of real eigenvalues. (fast track communication)
Synthesis of novel symmetrical macrocycle via oxidative homocoupling of bisalkyne
Energy Technology Data Exchange (ETDEWEB)
Kamalulazmy, Nurulain; Hassan, Nurul Izzaty [School of Chemical Sciences and Food Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor Darul Ehsan (Malaysia)
2014-09-03
A novel symmetrical macrocycle has been synthesised via oxidative homocoupling of bisalkyne, diprop-2-ynyl pyridine-2,6-dicarboxylate mediated by copper (I) iodide (CuI) and 4-dimethylaminopyridine (DMAP). The precursor compound was synthesised from 2,6-pyridine dicarbonyl dichloride and propargyl alcohol in the presence of triethylamine. The reaction mixture was stirred overnight and further purified via column chromatograpy with 76% yield. Single crystal for X-ray study was obtained by recrystallization from acetone. Subsequently, a symmetrical macrocycle was synthesised from oxidative homocoupling of precursor compound in open atmosphere. The crude product was purified by column chromatography to furnish macrocycle compound with 5% yield. Both compounds were characterised by IR, {sup 1}H and {sup 13}C NMR and mass spectral techniques. The unusual conformation of the bisalkyne and twisted conformation of designed macrocycle has influence the percentage yield. This has been studied thoroughly by X-ray crystallography and electronic structure calculations.
Information Retrieval and Criticality in Parity-Time-Symmetric Systems.
Kawabata, Kohei; Ashida, Yuto; Ueda, Masahito
2017-11-10
By investigating information flow between a general parity-time (PT-)symmetric non-Hermitian system and an environment, we find that the complete information retrieval from the environment can be achieved in the PT-unbroken phase, whereas no information can be retrieved in the PT-broken phase. The PT-transition point thus marks the reversible-irreversible criticality of information flow, around which many physical quantities such as the recurrence time and the distinguishability between quantum states exhibit power-law behavior. Moreover, by embedding a PT-symmetric system into a larger Hilbert space so that the entire system obeys unitary dynamics, we reveal that behind the information retrieval lies a hidden entangled partner protected by PT symmetry. Possible experimental situations are also discussed.
Symmetrical and overloaded effect of diffusion in information filtering
Zhu, Xuzhen; Tian, Hui; Chen, Guilin; Cai, Shimin
2017-10-01
In physical dynamics, mass diffusion theory has been applied to design effective information filtering models on bipartite network. In previous works, researchers unilaterally believe objects' similarities are determined by single directional mass diffusion from the collected object to the uncollected, meanwhile, inadvertently ignore adverse influence of diffusion overload. It in some extent veils the essence of diffusion in physical dynamics and hurts the recommendation accuracy and diversity. After delicate investigation, we argue that symmetrical diffusion effectively discloses essence of mass diffusion, and high diffusion overload should be published. Accordingly, in this paper, we propose an symmetrical and overload penalized diffusion based model (SOPD), which shows excellent performances in extensive experiments on benchmark datasets Movielens and Netflix.
EXCEPTIONAL POINTS IN OPEN AND PT-SYMMETRIC SYSTEMS
Directory of Open Access Journals (Sweden)
Hichem Eleuch
2014-04-01
Full Text Available Exceptional points (EPs determine the dynamics of open quantum systems and cause also PT symmetry breaking in PT symmetric systems. From a mathematical point of view, this is caused by the fact that the phases of the wavefunctions (eigenfunctions of a non-Hermitian Hamiltonian relative to one another are not rigid when an EP is approached. The system is therefore able to align with the environment to which it is coupled and, consequently, rigorous changes of the system properties may occur. We compare analytically as well as numerically the eigenvalues and eigenfunctions of a 2 × 2 matrix that is characteristic either of open quantum systems at high level density or of PT symmetric optical lattices. In both cases, the results show clearly the influence of the environment on the system in the neighborhood of EPs. Although the systems are very different from one another, the eigenvalues and eigenfunctions indicate the same characteristic features.
Biophysical information in asymmetric and symmetric diurnal bidirectional canopy reflectance
Vanderbilt, Vern C.; Caldwell, William F.; Pettigrew, Rita E.; Ustin, Susan L.; Martens, Scott N.; Rousseau, Robert A.; Berger, Kevin M.; Ganapol, B. D.; Kasischke, Eric S.; Clark, Jenny A.
1991-01-01
The authors present a theory for partitioning the information content in diurnal bidirectional reflectance measurements in order to detect differences potentially related to biophysical variables. The theory, which divides the canopy reflectance into asymmetric and symmetric functions of solar azimuth angle, attributes asymmetric variation to diurnal changes in the canopy biphysical properties. The symmetric function is attributed to the effects of sunlight interacting with a hypothetical average canopy which would display the average diurnal properties of the actual canopy. The authors analyzed radiometer data collected diurnally in the Thematic Mapper wavelength bands from two walnut canopies that received differing irrigation treatments. The reflectance of the canopies varied with sun and view angles and across seven bands in the visible, near-infrared, and middle infrared wavelength regions. Although one of the canopies was permanently water stressed and the other was stressed in mid-afternoon each day, no water stress signature was unambiguously evident in the reflectance data.
Implications of the Cosmological Constant for Spherically Symmetric Mass Distributions
Zubairi, Omair; Weber, Fridolin
2013-04-01
In recent years, scientists have made the discovery that the expansion rate of the Universe is increasing rather than decreasing. This acceleration leads to an additional term in Albert Einstein's field equations which describe general relativity and is known as the cosmological constant. This work explores the aftermath of a non-vanishing cosmological constant for relativistic spherically symmetric mass distributions, which are susceptible to change against Einstein's field equations. We introduce a stellar structure equation known as the Tolman-Oppenhiemer-Volkoff (TOV) equation modified for a cosmological constant, which is derived from Einstein's modified field equations. We solve this modified TOV equation for these spherically symmetric mass distributions and obtain stellar properties such as mass and radius and investigate changes that may occur depending on the value of the cosmological constant.
Maximal slicing of D-dimensional spherically symmetric vacuum spacetime
International Nuclear Information System (INIS)
Nakao, Ken-ichi; Abe, Hiroyuki; Yoshino, Hirotaka; Shibata, Masaru
2009-01-01
We study the foliation of a D-dimensional spherically symmetric black-hole spacetime with D≥5 by two kinds of one-parameter families of maximal hypersurfaces: a reflection-symmetric foliation with respect to the wormhole slot and a stationary foliation that has an infinitely long trumpetlike shape. As in the four-dimensional case, the foliations by the maximal hypersurfaces avoid the singularity irrespective of the dimensionality. This indicates that the maximal slicing condition will be useful for simulating higher-dimensional black-hole spacetimes in numerical relativity. For the case of D=5, we present analytic solutions of the intrinsic metric, the extrinsic curvature, the lapse function, and the shift vector for the foliation by the stationary maximal hypersurfaces. These data will be useful for checking five-dimensional numerical-relativity codes based on the moving puncture approach.
Thermal properties of self-gravitating plane-symmetric configuration
Energy Technology Data Exchange (ETDEWEB)
Hara, T; Ikeuchi, S [Kyoto Univ. (Japan). Dept. of Physics; Sugimoto, D
1976-09-01
As a limiting case of rotating stars, thermal properties of infinite plane-symmetric self-gravitating gas are investigated. Such a configuration is characterized by surface density of the plane instead of stellar mass. In the Kelvin contraction, temperature of the interior decreases, if the surface density is kept constant. If the accretion of matter takes place, or if the angular momenta are transferred outward, the surface density will increase. In this case, the temperature of the interior may increase. When a nuclear burning is ignited, it is thermally unstable in most cases, even when electrons are non-degenerate. This thermal instability is one of the essential differences of the plane-symmetric configuration from the spherical star. Such instabilities are computed for different cases of nuclear fuels. This type of nuclear instability is the same phenomenon as thermal instability of a thin shell burning in a spherical star.
Continuous symmetric reductions of the Adler-Bobenko-Suris equations
International Nuclear Information System (INIS)
Tsoubelis, D; Xenitidis, P
2009-01-01
Continuously symmetric solutions of the Adler-Bobenko-Suris class of discrete integrable equations are presented. Initially defined by their invariance under the action of both of the extended three-point generalized symmetries admitted by the corresponding equations, these solutions are shown to be determined by an integrable system of partial differential equations. The connection of this system to the Nijhoff-Hone-Joshi 'generating partial differential equations' is established and an auto-Baecklund transformation and a Lax pair for it are constructed. Applied to the H1 and Q1 δ=0 members of the Adler-Bobenko-Suris family, the method of continuously symmetric reductions yields explicit solutions determined by the Painleve trancendents
Exotic fermions in the left-right symmetric model
International Nuclear Information System (INIS)
Choi, J.; Volkas, R.R.
1992-01-01
A systematic study is made of non-standard fermion multiplets in left-right symmetric models with gauge group SU(3) x SU(2) L x SU(2) R x U(1) BL . Constraints from gauge anomaly cancellation and invariance of Yukawa coupling terms are used to define interesting classes of exotic fermions. The standard quark lepton spectrum of left-right symmetric models was identified as the simplest member of an infinite class. Phenomenological implications of the next simplest member of this class are then studied. Classes of exotic fermions which may couple to the standard fermions through doublet Higgs bosons were also considered, then shown that some of these exotics may be used to induce a generalised universal see-saw mechanism. 12 refs., 1 tab
Long-term repetition priming with symmetrical polygons and words.
Kersteen-Tucker, Z
1991-01-01
In two different tasks, subjects were asked to make lexical decisions (word or nonword) and symmetry judgments (symmetrical or nonsymmetrical) about two-dimensional polygons. In both tasks, every stimulus was repeated at one of four lags (0, 1, 4, or 8 items interposed between the first and second stimulus presentations). This paradigm, known as repetition priming, revealed comparable short-term priming (Lag 0) and long-term priming (Lags 1, 4, and 8) both for symmetrical polygons and for words. A shorter term component (Lags 0 and 1) of priming was observed for nonwords, and only very short-term priming (Lag 0) was observed for nonsymmetrical polygons. These results indicate that response facilitation accruing from repeated exposure can be observed for stimuli that have no preexisting memory representations and suggest that perceptual factors contribute to repetition-priming effects.
Admissible perturbations and false instabilities in PT -symmetric quantum systems
Znojil, Miloslav
2018-03-01
One of the most characteristic mathematical features of the PT -symmetric quantum mechanics is the explicit Hamiltonian dependence of its physical Hilbert space of states H =H (H ) . Some of the most important physical consequences are discussed, with emphasis on the dynamical regime in which the system is close to phase transition. Consistent perturbation treatment of such a regime is proposed. An illustrative application of the innovated perturbation theory to a non-Hermitian but PT -symmetric user-friendly family of J -parametric "discrete anharmonic" quantum Hamiltonians H =H (λ ⃗) is provided. The models are shown to admit the standard probabilistic interpretation if and only if the parameters remain compatible with the reality of the spectrum, λ ⃗∈D(physical ) . In contradiction to conventional wisdom, the systems are then shown to be stable with respect to admissible perturbations, inside the domain D(physical ), even in the immediate vicinity of the phase-transition boundaries ∂ D(physical ) .
PT-symmetric ladders with a scattering core
Energy Technology Data Exchange (ETDEWEB)
D' Ambroise, J. [Department of Mathematics, Amherst College, Amherst, MA 01002-5000 (United States); Lepri, S. [CNR – Consiglio Nazionale delle Ricerche, Istituto dei Sistemi Complessi, via Madonna del piano 10, I-50019 Sesto Fiorentino (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Firenze, via G. Sansone 1, I-50019 Sesto Fiorentino (Italy); Malomed, B.A. [Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 69978 (Israel); Kevrekidis, P.G. [Department of Mathematics and Statistics, University of Massachusetts, Amherst, MA 01003-9305 (United States)
2014-08-01
We consider a PT-symmetric chain (ladder-shaped) system governed by the discrete nonlinear Schrödinger equation where the cubic nonlinearity is carried solely by two central “rungs” of the ladder. Two branches of scattering solutions for incident plane waves are found. We systematically construct these solutions, analyze their stability, and discuss non-reciprocity of the transmission associated with them. To relate the results to finite-size wavepacket dynamics, we also perform direct simulations of the evolution of the wavepackets, which confirm that the transmission is indeed asymmetric in this nonlinear system with the mutually balanced gain and loss. - Highlights: • We model a PT-symmetric ladder system with cubic nonlinearity on two central rungs. • We examine non-reciprocity and stability of incident plane waves. • Simulations of wavepackets confirm our results.
The inverse spatial Laplacian of spherically symmetric spacetimes
International Nuclear Information System (INIS)
Fernandes, Karan; Lahiri, Amitabha
2017-01-01
We derive the inverse spatial Laplacian for static, spherically symmetric backgrounds by solving Poisson’s equation for a point source. This is different from the electrostatic Green function, which is defined on the four dimensional static spacetime, while the equation we consider is defined on the spatial hypersurface of such spacetimes. This Green function is relevant in the Hamiltonian dynamics of theories defined on spherically symmetric backgrounds, and closed form expressions for the solutions we find are absent in the literature. We derive an expression in terms of elementary functions for the Schwarzschild spacetime, and comment on the relation of this solution with the known Green function of the spacetime Laplacian operator. We also find an expression for the Green function on the static pure de-Sitter space in terms of hypergeometric functions. We conclude with a discussion of the constraints of the electromagnetic field. (paper)
Entanglement of polar symmetric top molecules as candidate qubits.
Wei, Qi; Kais, Sabre; Friedrich, Bretislav; Herschbach, Dudley
2011-10-21
Proposals for quantum computing using rotational states of polar molecules as qubits have previously considered only diatomic molecules. For these the Stark effect is second-order, so a sizable external electric field is required to produce the requisite dipole moments in the laboratory frame. Here we consider use of polar symmetric top molecules. These offer advantages resulting from a first-order Stark effect, which renders the effective dipole moments nearly independent of the field strength. That permits use of much lower external field strengths for addressing sites. Moreover, for a particular choice of qubits, the electric dipole interactions become isomorphous with NMR systems for which many techniques enhancing logic gate operations have been developed. Also inviting is the wider chemical scope, since many symmetric top organic molecules provide options for auxiliary storage qubits in spin and hyperfine structure or in internal rotation states. © 2011 American Institute of Physics
Ltaief, Hatem; Luszczek, Piotr R.; Haidar, Azzam; Dongarra, Jack
2012-01-01
This paper proposes an efficient implementation of the generalized symmetric eigenvalue problem on multicore architecture. Based on a four-stage approach and tile algorithms, the original problem is first transformed into a standard symmetric
Complex group algebras of the double covers of the symmetric and alternating group
DEFF Research Database (Denmark)
Bessenrodt, Christine; Nguyen, Hung Ngoc; Olsson, Jørn Børling
2015-01-01
We prove that the double covers of the alternating and symmetric groups are determined by their complex group algebras......We prove that the double covers of the alternating and symmetric groups are determined by their complex group algebras...
Procrustes Problems for General, Triangular, and Symmetric Toeplitz Matrices
Directory of Open Access Journals (Sweden)
Juan Yang
2013-01-01
Full Text Available The Toeplitz Procrustes problems are the least squares problems for the matrix equation AX=B over some Toeplitz matrix sets. In this paper the necessary and sufficient conditions are obtained about the existence and uniqueness for the solutions of the Toeplitz Procrustes problems when the unknown matrices are constrained to the general, the triangular, and the symmetric Toeplitz matrices, respectively. The algorithms are designed and the numerical examples show that these algorithms are feasible.
Superfield Lax formalism of supersymmetric sigma model on symmetric spaces
International Nuclear Information System (INIS)
Saleem, U.; Hassan, M.
2006-01-01
We present a superfield Lax formalism of the superspace sigma model based on the target space G/H and show that a one-parameter family of flat superfield connections exists if the target space G/H is a symmetric space. The formalism has been related to the existence of an infinite family of local and non-local superfield conserved quantities. A few examples have been given to illustrate the results. (orig.)
Two-parametric PT-symmetric quartic family
International Nuclear Information System (INIS)
Eremenko, Alexandre; Gabrielov, Andrei
2012-01-01
We describe a parametrization of the real spectral locus of the two-parametric family of PT-symmetric quartic oscillators. For this family, we find a parameter region where all eigenvalues are real, extending the results of Dorey et al (2007 J. Phys. A: Math Theor. 40 R205–83) and Shin (2005 J. Phys. A: Math. Gen. 38 6147–66; 2002 Commun. Math. Phys. 229 543–64). (paper)
Quantum cloning of mixed states in symmetric subspaces
International Nuclear Information System (INIS)
Fan Heng
2003-01-01
Quantum-cloning machine for arbitrary mixed states in symmetric subspaces is proposed. This quantum-cloning machine can be used to copy part of the output state of another quantum-cloning machine and is useful in quantum computation and quantum information. The shrinking factor of this quantum cloning achieves the well-known upper bound. When the input is identical pure states, two different fidelities of this cloning machine are optimal
Research on Characteristics of New Energy Dissipation With Symmetrical Structure
Ming, Wen; Huang, Chun-mei; Huang, Hao-wen; Wang, Xin-fang
2018-03-01
Utilizing good energy consumption capacity of arc steel bar, a new energy dissipation with symmetrical structure was proposed in this article. On the base of collection experimental data of damper specimen Under low cyclic reversed loading, finite element models were built by using ANSYS software, and influences of parameter change (Conduction rod diameter, Actuation plate thickness, Diameter of arc steel rod, Curved bars initial bending) on energy dissipation performance were analyzed. Some useful conclusions which can lay foundations for practical application were drawn.
Some problems in operator theory on bounded symmetric domains
Czech Academy of Sciences Publication Activity Database
Engliš, Miroslav
2004-01-01
Roč. 81, č. 1 (2004), s. 51-71 ISSN 0167-8019. [Representations of Lie groups, harmonic analysis on homogeneous spaces and quantization. Leiden, 07.12.2002-13.12.2002] R&D Projects: GA ČR GA201/03/0041 Institutional research plan: CEZ:AV0Z1019905 Keywords : homogeneous multiplication operators * bounded symmetric domains Subject RIV: BA - General Mathematics Impact factor: 0.354, year: 2004
${ \\mathcal P }{ \\mathcal T }$-symmetric interpretation of unstable effective potentials
Bender, Carl M.; Mavromatos, Nick E.; Sarkar, Sarben
2016-01-01
The conventional interpretation of the one-loop effective potentials of the Higgs field in the Standard Model and the gravitino condensate in dynamically broken supergravity is that these theories are unstable at large field values. A ${ \\mathcal P }{ \\mathcal T }$-symmetric reinterpretation of these models at a quantum-mechanical level eliminates these instabilities and suggests that these instabilities may also be tamed at the quantum-field-theory level.
Communication: Symmetrical quasi-classical analysis of linear optical spectroscopy
Provazza, Justin; Coker, David F.
2018-05-01
The symmetrical quasi-classical approach for propagation of a many degree of freedom density matrix is explored in the context of computing linear spectra. Calculations on a simple two state model for which exact results are available suggest that the approach gives a qualitative description of peak positions, relative amplitudes, and line broadening. Short time details in the computed dipole autocorrelation function result in exaggerated tails in the spectrum.
Dp spaces on bounded symmetric domains of Cn
International Nuclear Information System (INIS)
Shi Jihuai.
1989-06-01
In this paper, the space D p (Ω) of functions holomorphic on bounded symmetric domain of C m is defined. We prove that H p (Ω) is contained in D p (Ω) if 0 p (Ω) is contained in H p (Ω) if p ≥2, and both inclusions are proper. Further we find that some theorems on H p (Ω) can be extended to the wider class D p (Ω) for 0 < p ≤ 2. (author). 12 refs
A time-symmetric Universe model and its observational implication
International Nuclear Information System (INIS)
Futamase, T.; Matsuda, T.
1987-01-01
A time-symmetric closed-universe model is discussed in terms of the radiation arrow of time. The time symmetry requires the occurrence of advanced waves in the recontracting phase of the Universe. The observational consequences of such advanced waves are considered, and it is shown that a test observer in the expanding phase can observe a time-reversed image of a source of radiation in the future recontracting phase
Time-symmetric universe model and its observational implication
Energy Technology Data Exchange (ETDEWEB)
Futamase, T.; Matsuda, T.
1987-08-01
A time-symmetric closed-universe model is discussed in terms of the radiation arrow of time. The time symmetry requires the occurrence of advanced waves in the recontracting phase of the Universe. We consider the observational consequences of such advanced waves, and it is shown that a test observer in the expanding phase can observe a time-reversed image of a source of radiation in the future recontracting phase.
Weaving and neural complexity in symmetric quantum states
Susa, Cristian E.; Girolami, Davide
2018-04-01
We study the behaviour of two different measures of the complexity of multipartite correlation patterns, weaving and neural complexity, for symmetric quantum states. Weaving is the weighted sum of genuine multipartite correlations of any order, where the weights are proportional to the correlation order. The neural complexity, originally introduced to characterize correlation patterns in classical neural networks, is here extended to the quantum scenario. We derive closed formulas of the two quantities for GHZ states mixed with white noise.
New Classes of Quasi-helically Symmetric Stellarators
International Nuclear Information System (INIS)
Ku, L.P.; Boozer, A.H.
2010-01-01
New classes of quasi-helically symmetric stellarators with aspect ratios (le) 10 have been found which are stable to the perturbation of magnetohydrodynamic modes at plasma pressures of practical interest. These configurations have large rotational transform and good quality of flux surfaces. Characteristics of some selected examples are discussed in detail. The feasibility of using modular coils for these stellarators has been investigated. It is shown that practical designs for modular coils can be achieved.
IDEALS GENERATED BY LINEAR FORMS AND SYMMETRIC ALGEBRAS
Directory of Open Access Journals (Sweden)
Gaetana Restuccia
2016-01-01
Full Text Available We consider ideals generated by linear forms in the variables X1 : : : ;Xn in the polynomial ring R[X1; : : : ;Xn], being R a commutative, Noetherian ring with identity. We investigate when a sequence a1; a2; : : : ; am of linear forms is an ssequence, in order to compute algebraic invariants of the symmetric algebra of the ideal I = (a1; a2; : : : ; am.
Factoring symmetric indefinite matrices on high-performance architectures
Jones, Mark T.; Patrick, Merrell L.
1990-01-01
The Bunch-Kaufman algorithm is the method of choice for factoring symmetric indefinite matrices in many applications. However, the Bunch-Kaufman algorithm does not take advantage of high-performance architectures such as the Cray Y-MP. Three new algorithms, based on Bunch-Kaufman factorization, that take advantage of such architectures are described. Results from an implementation of the third algorithm are presented.
Modulation of precipitation by conditional symmetric instability release
Glinton, Michael R.; Gray, Suzanne L.; Chagnon, Jeffrey M.; Morcrette, Cyril J.
2017-01-01
Although many theoretical and observational studies have investigated the mechanism of conditional symmetric instability (CSI) release and associated it with mesoscale atmospheric phenomena such as frontal precipitation bands, cloud heads in rapidly developing extratropical cyclones and sting jets, its climatology and contribution to precipitation have not been extensively documented. The aim of this paper is to quantify the contribution of CSI release, yielding slantwise convection, to clima...
Static axially symmetric gravitational fields with shell sources
International Nuclear Information System (INIS)
McCrea, J.D.
1976-01-01
Israel's (Israel, W., 1966, Nuovo Cim., vol.44, 1-14) method for treating surface layers in general relativity is applied to construct shell sources for exterior static axially symmetric gravitational fields. Consideration is restricted to cases in which the 3-cylinder representing the history of the shell is an equipotential surface of the exterior field and consequently the space-time inside this 3-cylinder is flat. (author)
Symmetric positive differential equations and first order hyperbolic systems
International Nuclear Information System (INIS)
Tangmanee, S.
1981-12-01
We prove that under some conditions the first order hyperbolic system and its associated mixed initial boundary conditions considered, for example, in Kreiss (Math. Comp. 22, 703-704 (1968)) and Kreiss and Gustafsson (Math. Comp. 26, 649-686 (1972)), can be transformed into a symmetric positive system of P.D.E.'s with admissible boundary conditions of Friedrich's type (Comm. Pure Appl. Math 11, 333-418 (1958)). (author)
The symmetric group and its relevance to fermion physics
International Nuclear Information System (INIS)
Harvey, M.
1981-04-01
Notes are given of a series of lectures presented at TRIUMF (Vancouver) during the week of October 17-24, 1980. The lectures, and accompanying notes were designed to give the student a working knowledge of the classification and construction of sets of n-particle states transforming according to a definite irreducible representation of the symmetric group Ssub(n). Applications are given for the classification of quark states of baryons and multibaryons
Vibrational motion in a symmetric, double minimum potential
DEFF Research Database (Denmark)
Spanget-Larsen, Jens
2015-01-01
Molecular vibrational motion in a symmetric, double minimum potential is treated by means of a quartic model potential, by reference to the tables published by Jaan Laane and the results of harmonic analyses for the stationary points. The inversion vibration of ammonia is treated in detail. - Not...... on the harmonic approximation for polyatomic molecules are appended. - Presented at a NORFA Workshop in Hirtshals, Denmark, August 1997....
Extensions of the Hardy-Littlewood inequalities for Schwarz symmetrization
Directory of Open Access Journals (Sweden)
H. Hajaiej
2004-01-01
Full Text Available For a class of functions H:(0,∞×ℝ+2→ℝ, including discontinuous functions of Carathéodory type, we establish that ∫ℝNH(|x|,u(x,v(xdx≤∫ℝNH(|x|,u*(x,v*(xdx, where u*(x and v*(x denote the Schwarz symmetrizations of nonnegative functions u and v.
A symmetric positive definite formulation for monolithic fluid structure interaction
Robinson-Mosher, Avi; Schroeder, Craig; Fedkiw, Ronald
2011-01-01
In this paper we consider a strongly coupled (monolithic) fluid structure interaction framework for incompressible flow, as opposed to a loosely coupled (partitioned) method. This requires solving a single linear system that combines the unknown velocities of the structure with the unknown pressures of the fluid. In our previous work, we were able to obtain a symmetric formulation of this coupled system; however, it was also indefinite, making it more difficult to solve. In fact in practice there have been cases where we have been unable to invert the system. In this paper we take a novel approach that consists of factoring the damping matrix of deformable structures and show that this can be used to obtain a symmetric positive definite system, at least to the extent that the uncoupled systems were symmetric positive definite. We use a traditional MAC grid discretization of the fluid and a fully Lagrangian discretization of the structures for the sake of exposition, noting that our procedure can be generalized to other scenarios. For the special case of rigid bodies, where there are no internal damping forces, we exactly recover the system of Batty et al. (2007) [4]. © 2010 Elsevier Inc.
Symmetric and asymmetric nuclear matter in the relativistic approach
International Nuclear Information System (INIS)
Huber, H.; Weber, F.; Weigel, M.K.
1995-01-01
Symmetric and asymmetric nuclear matter is studied in the framework of the relativistic Brueckner-Hartree-Fock and in the relativistic version of the so-called Λ 00 approximation. The equations are solved self-consistently in the full Dirac space, so avoiding the ambiguities in the choice of the effective scattering amplitude in matter. The calculations were performed for some modern meson-exchange potentials constructed by Brockmann and Machleidt. In some cases we used also the Groningen potentials. First, we examine the outcome for symmetric matter with respect to other calculations, which restrict themselves to positive-energy states only. The main part is devoted to the properties of asymmetric matter. In this case we obtain additionally to the good agreement with the parameters of symmetric matter, also a quite satisfactory agreement with the semiempirical macroscopic coefficients of asymmetric matter. Furthermore, we tested the assumption of a quadratic dependence of the asymmetry energy for a large range of asymmetries. Included is also the dependence of nucleon self-energies on density and neutron excess. For the purpose of comparison we discuss further the similarities and differences with relativistic Hartree and Hartree-Fock calculations and nonrelativistic Skyrme calculations
Symmetric large momentum transfer for atom interferometry with BECs
Abend, Sven; Gebbe, Martina; Gersemann, Matthias; Rasel, Ernst M.; Quantus Collaboration
2017-04-01
We develop and demonstrate a novel scheme for a symmetric large momentum transfer beam splitter for interferometry with Bose-Einstein condensates. Large momentum transfer beam splitters are a key technique to enhance the scaling factor and sensitivity of an atom interferometer and to create largely delocalized superposition states. To realize the beam splitter, double Bragg diffraction is used to create a superposition of two symmetric momentum states. Afterwards both momentum states are loaded into a retro-reflected optical lattice and accelerated by Bloch oscillations on opposite directions, keeping the initial symmetry. The favorable scaling behavior of this symmetric acceleration, allows to transfer more than 1000 ℏk of total differential splitting in a single acceleration sequence of 6 ms duration while we still maintain a fraction of approx. 25% of the initial atom number. As a proof of the coherence of this beam splitter, contrast in a closed Mach-Zehnder atom interferometer has been observed with up to 208 ℏk of momentum separation, which equals a differential wave-packet velocity of approx. 1.1 m/s for 87Rb. The presented work is supported by the CRC 1128 geo-Q and the DLR with funds provided by the Federal Ministry of Economic Affairs and Energy (BMWi) due to an enactment of the German Bundestag under Grant No. DLR 50WM1552-1557 (QUANTUS-IV-Fallturm).
Maximum-confidence discrimination among symmetric qudit states
International Nuclear Information System (INIS)
Jimenez, O.; Solis-Prosser, M. A.; Delgado, A.; Neves, L.
2011-01-01
We study the maximum-confidence (MC) measurement strategy for discriminating among nonorthogonal symmetric qudit states. Restricting to linearly dependent and equally likely pure states, we find the optimal positive operator valued measure (POVM) that maximizes our confidence in identifying each state in the set and minimizes the probability of obtaining inconclusive results. The physical realization of this POVM is completely determined and it is shown that after an inconclusive outcome, the input states may be mapped into a new set of equiprobable symmetric states, restricted, however, to a subspace of the original qudit Hilbert space. By applying the MC measurement again onto this new set, we can still gain some information about the input states, although with less confidence than before. This leads us to introduce the concept of sequential maximum-confidence (SMC) measurements, where the optimized MC strategy is iterated in as many stages as allowed by the input set, until no further information can be extracted from an inconclusive result. Within each stage of this measurement our confidence in identifying the input states is the highest possible, although it decreases from one stage to the next. In addition, the more stages we accomplish within the maximum allowed, the higher will be the probability of correct identification. We will discuss an explicit example of the optimal SMC measurement applied in the discrimination among four symmetric qutrit states and propose an optical network to implement it.
A symmetric positive definite formulation for monolithic fluid structure interaction
Robinson-Mosher, Avi
2011-02-01
In this paper we consider a strongly coupled (monolithic) fluid structure interaction framework for incompressible flow, as opposed to a loosely coupled (partitioned) method. This requires solving a single linear system that combines the unknown velocities of the structure with the unknown pressures of the fluid. In our previous work, we were able to obtain a symmetric formulation of this coupled system; however, it was also indefinite, making it more difficult to solve. In fact in practice there have been cases where we have been unable to invert the system. In this paper we take a novel approach that consists of factoring the damping matrix of deformable structures and show that this can be used to obtain a symmetric positive definite system, at least to the extent that the uncoupled systems were symmetric positive definite. We use a traditional MAC grid discretization of the fluid and a fully Lagrangian discretization of the structures for the sake of exposition, noting that our procedure can be generalized to other scenarios. For the special case of rigid bodies, where there are no internal damping forces, we exactly recover the system of Batty et al. (2007) [4]. © 2010 Elsevier Inc.
The critical current of point symmetric Josephson tunnel junctions
International Nuclear Information System (INIS)
Monaco, Roberto
2016-01-01
Highlights: • We disclose some geometrical properties of the critical current field dependence that apply to a large class of Josephson junctions characterized by a point symmetric shape. • The developed theory is valid for any orientation of the applied magnetic field, therefore it allows the determine the consequences of field misalignment in the experimental setups. • We also address that the threshold curves of Josephson tunnel junctions with complex shapes can be expressed as a linear combination of the threshold curves of junctions with simpler point symmetric shapes. - Abstract: The physics of Josephson tunnel junctions drastically depends on their geometrical configurations. The shape of the junction determines the specific form of the magnetic-field dependence of its Josephson current. Here we address the magnetic diffraction patterns of specially shaped planar Josephson tunnel junctions in the presence of an in-plane magnetic field of arbitrary orientations. We focus on a wide ensemble of junctions whose shape is invariant under point reflection. We analyze the implications of this type of isometry and derive the threshold curves of junctions whose shape is the union or the relative complement of two point symmetric plane figures.
Bright Solitons in a PT-Symmetric Chain of Dimers
Directory of Open Access Journals (Sweden)
Omar B. Kirikchi
2016-01-01
Full Text Available We study the existence and stability of fundamental bright discrete solitons in a parity-time- (PT- symmetric coupler composed by a chain of dimers that is modelled by linearly coupled discrete nonlinear Schrödinger equations with gain and loss terms. We use a perturbation theory for small coupling between the lattices to perform the analysis, which is then confirmed by numerical calculations. Such analysis is based on the concept of the so-called anticontinuum limit approach. We consider the fundamental onsite and intersite bright solitons. Each solution has symmetric and antisymmetric configurations between the arms. The stability of the solutions is then determined by solving the corresponding eigenvalue problem. We obtain that both symmetric and antisymmetric onsite mode can be stable for small coupling, in contrast to the reported continuum limit where the antisymmetric solutions are always unstable. The instability is either due to the internal modes crossing the origin or the appearance of a quartet of complex eigenvalues. In general, the gain-loss term can be considered parasitic as it reduces the stability region of the onsite solitons. Additionally, we analyse the dynamic behaviour of the onsite and intersite solitons when unstable, where typically it is either in the form of travelling solitons or soliton blow-ups.
Asymptotic properties of solvable PT-symmetric potentials
International Nuclear Information System (INIS)
Levai, G.
2010-01-01
Compete text of publication follows. The introduction of PT-symmetric quantum mechanics generated renewed interest in non-hermitian quantum mechanical systems in the past decade. PT symmetry means the invariance of a Hamiltonian under the simultaneous P space and T time reflection, the latter understood as complex conjugation. Considering the Schroedinger equation in one dimension, this corresponds to a potential with even real and odd imaginary components. This implies a delicate balance of emissive and absorptive regions that eventually manifests itself in properties that typically characterize real potentials, i.e. hermitian systems. These include partly or fully real energy spectrum and conserved (pseudo-)norm. A particularly notable feature of these systems is the spontaneous breakdown of PT symmetry, which typically occurs when the magnitude of the imaginary potential component exceeds a certain limit. At this point the real energy eigenvalues begin to merge pairwise and re-emerge as complex conjugate pairs. Another unusual property of PT-symmetric potentials is that they can, or sometimes have to be defined off the real x axis on trajectories that are symmetric with respect to the imaginary x axis. After more than a decade of theoretical investigations a remarkable recent development was the experimental verification of the existence of PT-symmetric systems in nature and the occurrence of spontaneous PT symmetry breaking in them. The experimental setup was a waveguide containing regions where loss and gain of flux occurred in a set out prescribed by PT symmetry. These experimental developments require the study of PT -symmetric potentials with various asymptotics, in which, furthermore, the complex potential component is finite in its range and/or its magnitude. Having in mind that PT symmetry allows for a wider variety of asymptotic properties than hermeticity, we studied three exactly solvable PT-symmetric potentials and compared their scattering and bound
Design of tryptophan-containing mutants of the symmetrical Pizza protein for biophysical studies.
Noguchi, Hiroki; Mylemans, Bram; De Zitter, Elke; Van Meervelt, Luc; Tame, Jeremy R H; Voet, Arnout
2018-03-18
β-propeller proteins are highly symmetrical, being composed of a repeated motif with four anti-parallel β-sheets arranged around a central axis. Recently we designed the first completely symmetrical β-propeller protein, Pizza6, consisting of six identical tandem repeats. Pizza6 is expected to prove a useful building block for bionanotechnology, and also a tool to investigate the folding and evolution of β-propeller proteins. Folding studies are made difficult by the high stability and the lack of buried Trp residues to act as monitor fluorophores, so we have designed and characterized several Trp-containing Pizza6 derivatives. In total four proteins were designed, of which three could be purified and characterized. Crystal structures confirm these mutant proteins maintain the expected structure, and a clear redshift of Trp fluorescence emission could be observed upon denaturation. Among the derivative proteins, Pizza6-AYW appears to be the most suitable model protein for future folding/unfolding kinetics studies as it has a comparable stability as natural β-propeller proteins. Copyright © 2018 Elsevier Inc. All rights reserved.
Ma, Yuanyuan; Hu, Xiaohua; He, Tingting; Jiang, Xingpeng
2016-12-01
Nonnegative matrix factorization (NMF) has received considerable attention due to its interpretation of observed samples as combinations of different components, and has been successfully used as a clustering method. As an extension of NMF, Symmetric NMF (SNMF) inherits the advantages of NMF. Unlike NMF, however, SNMF takes a nonnegative similarity matrix as an input, and two lower rank nonnegative matrices (H, H T ) are computed as an output to approximate the original similarity matrix. Laplacian regularization has improved the clustering performance of NMF and SNMF. However, Laplacian regularization (LR), as a classic manifold regularization method, suffers some problems because of its weak extrapolating ability. In this paper, we propose a novel variant of SNMF, called Hessian regularization based symmetric nonnegative matrix factorization (HSNMF), for this purpose. In contrast to Laplacian regularization, Hessian regularization fits the data perfectly and extrapolates nicely to unseen data. We conduct extensive experiments on several datasets including text data, gene expression data and HMP (Human Microbiome Project) data. The results show that the proposed method outperforms other methods, which suggests the potential application of HSNMF in biological data clustering. Copyright Â© 2016. Published by Elsevier Inc.
Directory of Open Access Journals (Sweden)
Kenichi Kondo
2013-11-01
Full Text Available Ultradiscretization with negative values is a long-standing problem and several attempts have been made to solve it. Among others, we focus on the symmetrized max-plus algebra, with which we ultradiscretize the discrete sine-Gordon equation. Another ultradiscretization of the discrete sine-Gordon equation has already been proposed by previous studies, but the equation and the solutions obtained here are considered to directly correspond to the discrete counterpart. We also propose a noncommutative discrete analogue of the sine-Gordon equation, reveal its relations to other integrable systems including the noncommutative discrete KP equation, and construct multisoliton solutions by a repeated application of Darboux transformations. Moreover, we derive a noncommutative ultradiscrete analogue of the sine-Gordon equation and its 1-soliton and 2-soliton solutions, using the symmetrized max-plus algebra. As a result, we have a complete set of commutative and noncommutative versions of continuous, discrete, and ultradiscrete sine-Gordon equations.
Azzam, R M A
2015-12-01
Conditions for achieving equal and opposite angular deflections of a light beam by reflection and refraction at an air-dielectric boundary are determined. Such angularly symmetric beam splitting (ASBS) is possible only if the angle of incidence is >60° by exactly one third of the angle of refraction. This simple law, plus Snell's law, leads to several analytical results that clarify all aspects of this phenomenon. In particular, it is shown that the intensities of the two symmetrically deflected beams can be equalized by proper choice of the prism refractive index and the azimuth of incident linearly polarized light. ASBS enables a geometrically attractive layout of optical systems that employ multiple prism beam splitters.
New Approaches to Treatment of Severe Intrauterine Growth Restriction
Directory of Open Access Journals (Sweden)
Zhanar Kurmangali
2014-12-01
Full Text Available Introduction. Intrauterine growth restriction (IUGR is a leading cause of perinatal morbidity and mortality due to placental insufficiency. Currently, one of the new approaches to treating this disease is the injection of nutrients to the fetus through intravascular port-systems (catheters.Objective. To assess the impact of nutrient injections as treatment to fetuses with severe growth retardation.Materials and methods. Pregnant women with IUGR (abdominal circumference (AC < 5th percentile with the absence of diastolic flow in the umbilical artery and a fetal gestational age of less than 30 weeks were randomly divided into two groups. The treatment group included six pregnant women who had an intravascular port-system for the infusion of nutrients (amino acids and glucose in the umbilical vein of the fetus for 14 ± 3 days. The control group consisted of eight patients who received only traditional dynamic monitoring and delivery at the optimum time of pregnancy. Fetal status was assessed using ultrasound equipment Accuvix V20 (Medison, South Korea by examining indicators of biometry and Doppler study of blood flow in utero, umbilical arteries, middle cerebral artery, and ductus venosus with fetal vascular resistance index calculation - pulsatility index (PI. Criteria for blood flow disturbances in the vessels were considered PI values above normal values for their gestational age, which were defined as absence or reverse blood flow in a diastole in the umbilical artery.Results. In a comparative analysis of the two groups, the treatment led to a 44.7% increase in AC of the fetus (121.0 ± 11.5 mm and 219.3 ± 18.3 mm, respectively, p ˂ 0.001. In all cases, the profile of blood flow in the umbilical artery had a positive diastolic component. As a result, there was a 45.3% decrease in PI in the umbilical artery (2.14 ± 0.54 and 1.17 ± 0.15, respectively, p < 0.05. Average fetal weight in the study group was not significantly higher than the
The rationality of EIA forecasts under symmetric and asymmetric loss
International Nuclear Information System (INIS)
Auffhammer, Maximilian
2007-01-01
The United States Energy Information Administration publishes annual forecasts of nationally aggregated energy consumption, production, prices, intensity and GDP. These government issued forecasts often serve as reference cases in the calibration of simulation and econometric models, which climate and energy policy are based on. This study tests for rationality of published EIA forecasts under symmetric and asymmetric loss. We find strong empirical evidence of asymmetric loss for oil, coal and electricity prices as well as natural gas consumption, electricity sales, GDP and energy intensity. (author)
20th International Workshop on Hermitian Symmetric Spaces and Submanifolds
Ohnita, Yoshihiro; Zhou, Jiazu; Kim, Byung; Lee, Hyunjin
2017-01-01
This book presents the proceedings of the 20th International Workshop on Hermitian Symmetric Spaces and Submanifolds, which was held at the Kyungpook National University from June 21 to 25, 2016. The Workshop was supported by the Research Institute of Real and Complex Manifolds (RIRCM) and the National Research Foundation of Korea (NRF). The Organizing Committee invited 30 active geometers of differential geometry and related fields from all around the globe to discuss new developments for research in the area. These proceedings provide a detailed overview of recent topics in the field of real and complex submanifolds.
The Topology of Three-Dimensional Symmetric Tensor Fields
Lavin, Yingmei; Levy, Yuval; Hesselink, Lambertus
1994-01-01
We study the topology of 3-D symmetric tensor fields. The goal is to represent their complex structure by a simple set of carefully chosen points and lines analogous to vector field topology. The basic constituents of tensor topology are the degenerate points, or points where eigenvalues are equal to each other. First, we introduce a new method for locating 3-D degenerate points. We then extract the topological skeletons of the eigenvector fields and use them for a compact, comprehensive description of the tensor field. Finally, we demonstrate the use of tensor field topology for the interpretation of the two-force Boussinesq problem.
Symmetric wetting heterogeneity suppresses fluid displacement hysteresis in granular piles
Moosavi, R.; Schröter, M.; Herminghaus, S.
2018-02-01
We investigate experimentally the impact of heterogeneity on the capillary pressure hysteresis in fluid invasion of model porous media. We focus on symmetric heterogeneity, where the contact angles the fluid interface makes with the oil-wet (θ1) and the water-wet (θ2) beads add up to π . While enhanced heterogeneity is usually known to increase hysteresis phenomena, we find that hysteresis is greatly reduced when heterogeneities in wettability are introduced. On the contrary, geometric heterogeneity (like bidisperse particle size) does not lead to such an effect. We provide a qualitative explanation of this surprising result, resting on rather general geometric arguments.
Optical force rectifiers based on PT-symmetric metasurfaces
Alaee, Rasoul; Gurlek, Burak; Christensen, Johan; Kadic, Muamer
2018-05-01
We introduce here the concept of optical force rectifier based on parity-time symmetric metasurfaces. Directly linked to the properties of non-Hermitian systems engineered by balanced loss and gain constituents, we show that light can exert asymmetric pulling or pushing forces on metasurfaces depending on the direction of the impinging light. This generates a complete force rectification in the vicinity of the exceptional point. Our findings have the potential to spark the design of applications in optical manipulation where the forces, strictly speaking, act unidirectionally.
Exact quantum solution for some symmetrical two-well potentials
International Nuclear Information System (INIS)
Ley-Koo, E.
1985-01-01
We construct the solutions of the Schroedinger equation for the rectangular-well, harmonic-oscillator and symmetric-linear potentials with a delta-function potential superimposed in their central positions. The odd-parity states are not affected by the presence of the delta-function potential. The even-parity states are determined by the condition that their wave functions have in the central position a fixed logarithmic derivative, which is proportional to the intensity the delta-function potential. (author)
Spherically symmetric solution and a satisfactory energy-momentum complex
International Nuclear Information System (INIS)
Nashed, G.G.L.
2005-01-01
Mikhail et al. obtained two spherically symmetric solution in Moeller tetrad theory of gravitation. They calculated their energy content and obtained a strange value for the second solution, in spite that the associated metric of these solutions is the same (the Schwarzschild metric). We use another method given bu Gibbons and Hawking to calculate the energy content of these solutions. We also obtained a strange value of energy for the second solution. Studying the requirements of the satisfactory energy-momentum complex given by Moeller we find that the second solution which behaves as 1/√r does not transform as a four-vector under Lorentz transformation
Dispersion in a bent-solenoid channel with symmetric focusing
Energy Technology Data Exchange (ETDEWEB)
Wang, Chun-xi [Argonne National Lab. (ANL), Argonne, IL (United States)
2001-08-21
Longitudinal ionization cooling of a muon beam is essential for muon colliders and will be useful for neutrino factories. Bent-solenoid channels with symmetric focusing has been considered for beam focusing and for generating the required dispersion in the ``emittance exchange'' scheme of longitudinal cooling. In this paper, we derive the Hamiltonian that governs the linear beam dynamics of a bent-solenoid channel, solve the single-particle dynamics, and give equations for determining the lattice functions, in particular, the dispersion functions.
Smooth Gowdy-symmetric generalized Taub–NUT solutions
International Nuclear Information System (INIS)
Beyer, Florian; Hennig, Jörg
2012-01-01
We study a class of S 3 -Gowdy vacuum models with a regular past Cauchy horizon which we call smooth Gowdy-symmetric generalized Taub–NUT solutions. In particular, we prove the existence of such solutions by formulating a singular initial value problem with asymptotic data on the past Cauchy horizon. We prove that also a future Cauchy horizon exists for generic asymptotic data, and derive an explicit expression for the metric on the future Cauchy horizon in terms of the asymptotic data on the past horizon. This complements earlier results about S 1 ×S 2 -Gowdy models. (paper)
Spherically symmetric near-critical accretion onto neutron stars
International Nuclear Information System (INIS)
Miller, G.S.
1990-01-01
Numerical and approximate analytic solutions for time-independent, spherically symmetric, radiation pressure-dominated accretion flows are presented. For flows with luminosities at infinity, L-infinity, sufficiently close to the Eddington limit L-crit, the flow velocity profile is qualitatively different from the modified free-fall profile v(r) = (1 - L-infinity/L-crit)exp 1/2 (2GM/r)exp 1/2. Advective contributions to the comoving radiation flux decelerate the flow within a criical radius, and, in this settling region, the velocity of the flow decreases linearly with decreasing radius. 14 refs
Spherically symmetric static spacetimes in vacuum f(T) gravity
International Nuclear Information System (INIS)
Ferraro, Rafael; Fiorini, Franco
2011-01-01
We show that Schwarzschild geometry remains as a vacuum solution for those four-dimensional f(T) gravitational theories behaving as ultraviolet deformations of general relativity. In the gentler context of three-dimensional gravity, we also find that the infrared-deformed f(T) gravities, like the ones used to describe the late cosmic speed up of the Universe, have as the circularly symmetric vacuum solution a Deser-de Sitter or a Banados, Teitelboim and Zanelli-like spacetime with an effective cosmological constant depending on the infrared scale present in the function f(T).
Rotationally symmetric structure in two extragalactic radio sources
International Nuclear Information System (INIS)
Lonsdale, C.J.; Morison, I.
1980-01-01
The new multi-telescope radio-linked interferometer (MTRLI) at Jodrell Bank was used during January and February 1980 at a frequency of 408 MHz to map the extragalactic radio sources 3C196 and 3C305 with a resolution of approximately 1 arc s. It is shown here that both the markedly symmetric structures observed and the spectral index distributions inferred from comparisons with previously published 5 GHz maps provide evidence for the source axes having rotated during the lifetime of the emitting regions. (U.K.)
Noise from Propellers with Symmetrical Sections at Zero Blade Angle
Deming, A F
1937-01-01
A theory has been deduced for the "rotation noise" from a propeller with blades of symmetrical section about the chord line and set at zero blade angle. Owing to the limitation of the theory, the equations give without appreciable error only the sound pressure for cases where the wave lengths are large compared with the blade lengths. With the aid of experimental data obtained from a two-blade arrangement, an empirical relation was introduced that permitted calculation of higher harmonics. The generality of the final relation given is indicated by the fundamental and second harmonic of a four-blade arrangement.
Hardware Realization of Chaos Based Symmetric Image Encryption
Barakat, Mohamed L.
2012-06-01
This thesis presents a novel work on hardware realization of symmetric image encryption utilizing chaos based continuous systems as pseudo random number generators. Digital implementation of chaotic systems results in serious degradations in the dynamics of the system. Such defects are illuminated through a new technique of generalized post proceeding with very low hardware cost. The thesis further discusses two encryption algorithms designed and implemented as a block cipher and a stream cipher. The security of both systems is thoroughly analyzed and the performance is compared with other reported systems showing a superior results. Both systems are realized on Xilinx Vetrix-4 FPGA with a hardware and throughput performance surpassing known encryption systems.
Minimal Length Effects on Tunnelling from Spherically Symmetric Black Holes
Directory of Open Access Journals (Sweden)
Benrong Mu
2015-01-01
Full Text Available We investigate effects of the minimal length on quantum tunnelling from spherically symmetric black holes using the Hamilton-Jacobi method incorporating the minimal length. We first derive the deformed Hamilton-Jacobi equations for scalars and fermions, both of which have the same expressions. The minimal length correction to the Hawking temperature is found to depend on the black hole’s mass and the mass and angular momentum of emitted particles. Finally, we calculate a Schwarzschild black hole's luminosity and find the black hole evaporates to zero mass in infinite time.
Symmetric-Galerkin BEM simulation of fracture with frictional contact
CSIR Research Space (South Africa)
Phan, AV
2003-06-14
Full Text Available FOR NUMERICAL METHODS IN ENGINEERING Int. J. Numer. Meth. Engng 2003; 57:835?851 (DOI: 10.1002/nme.707) Symmetric-Galerkin BEM simulation of fracture with frictional contact A.-V. Phan1;asteriskmath;?, J. A. L. Napier2, L. J. Gray3 and T. Kaplan3 1Department... Methods in Engineering 1975; 9:495?507. 35. Barsoum RS. On the use of isoparametric FFnite elements in linear fracture mechanics. International Journal for Numerical Methods in Engineering 1976; 10:25?37. 36. Gray LJ, Phan A-V, Paulino GH, Kaplan T...
Constructing quantum games from symmetric non-factorizable joint probabilities
Energy Technology Data Exchange (ETDEWEB)
Chappell, James M., E-mail: james.m.chappell@adelaide.edu.a [School of Chemistry and Physics, University of Adelaide, South Australia 5005 (Australia); School of Electrical and Electronic Engineering, University of Adelaide, South Australia 5005 (Australia); Iqbal, Azhar [School of Electrical and Electronic Engineering, University of Adelaide, South Australia 5005 (Australia); Centre for Advanced Mathematics and Physics, National University of Sciences and Technology, Peshawar Road, Rawalpindi (Pakistan); Abbott, Derek [School of Electrical and Electronic Engineering, University of Adelaide, South Australia 5005 (Australia)
2010-09-06
We construct quantum games from a table of non-factorizable joint probabilities, coupled with a symmetry constraint, requiring symmetrical payoffs between the players. We give the general result for a Nash equilibrium and payoff relations for a game based on non-factorizable joint probabilities, which embeds the classical game. We study a quantum version of Prisoners' Dilemma, Stag Hunt, and the Chicken game constructed from a given table of non-factorizable joint probabilities to find new outcomes in these games. We show that this approach provides a general framework for both classical and quantum games without recourse to the formalism of quantum mechanics.
Classically integrable boundary conditions for symmetric-space sigma models
International Nuclear Information System (INIS)
MacKay, N.J.; Young, C.A.S.
2004-01-01
We investigate boundary conditions for the non-linear sigma model on the compact symmetric space G/H. The Poisson brackets and the classical local conserved charges necessary for integrability are preserved by boundary conditions which correspond to involutions which commute with the involution defining H. Applied to SO(3)/SO(2), the non-linear sigma model on S 2 , these yield the great circles as boundary submanifolds. Applied to GxG/G, they reproduce known results for the principal chiral model
Baryon symmetric big-bang cosmology. [matter-antimatter symmetry
Stecker, F. W.
1978-01-01
The framework of baryon-symmetric big-bang cosmology offers the greatest potential for deducing the evolution of the universe as a consequence of physical laws and processes with the minimum number of arbitrary assumptions as to initial conditions in the big-bang. In addition, it offers the possibility of explaining the photon-baryon ratio in the universe and how galaxies and galaxy clusters are formed, and also provides the only acceptable explanation at present for the origin of the cosmic gamma ray background radiation.
Alignment of symmetric top molecules by short laser pulses
DEFF Research Database (Denmark)
Hamilton, Edward; Seideman, Tamar; Ejdrup, Tine
2005-01-01
-resolved photofragment imaging. Using methyliodide and tert-butyliodide as examples, we calculate and measure the alignment dynamics, focusing on the temporal structure and intensity of the revival patterns, including their dependence on the pulse duration, and their behavior at long times, where centrifugal distortion......Nonadiabatic alignment of symmetric top molecules induced by a linearly polarized, moderately intense picosecond laser pulse is studied theoretically and experimentally. Our studies are based on the combination of a nonperturbative solution of the Schrodinger equation with femtosecond time...
Broadband sound blocking in phononic crystals with rotationally symmetric inclusions.
Lee, Joong Seok; Yoo, Sungmin; Ahn, Young Kwan; Kim, Yoon Young
2015-09-01
This paper investigates the feasibility of broadband sound blocking with rotationally symmetric extensible inclusions introduced in phononic crystals. By varying the size of four equally shaped inclusions gradually, the phononic crystal experiences remarkable changes in its band-stop properties, such as shifting/widening of multiple Bragg bandgaps and evolution to resonance gaps. Necessary extensions of the inclusions to block sound effectively can be determined for given incident frequencies by evaluating power transmission characteristics. By arraying finite dissimilar unit cells, the resulting phononic crystal exhibits broadband sound blocking from combinational effects of multiple Bragg scattering and local resonances even with small-numbered cells.
A parallel algorithm for the non-symmetric eigenvalue problem
International Nuclear Information System (INIS)
Sidani, M.M.
1991-01-01
An algorithm is presented for the solution of the non-symmetric eigenvalue problem. The algorithm is based on a divide-and-conquer procedure that provides initial approximations to the eigenpairs, which are then refined using Newton iterations. Since the smaller subproblems can be solved independently, and since Newton iterations with different initial guesses can be started simultaneously, the algorithm - unlike the standard QR method - is ideal for parallel computers. The author also reports on his investigation of deflation methods designed to obtain further eigenpairs if needed. Numerical results from implementations on a host of parallel machines (distributed and shared-memory) are presented
Quantum Dialogue by Using Non-Symmetric Quantum Channel
International Nuclear Information System (INIS)
Zhan Youbang; Zhang Lingling; Zhang Qunyong; Wang Yuwu
2010-01-01
A protocol for quantum dialogue is proposed to exchange directly the communicator's secret messages by using a three-dimensional Bell state and a two-dimensional Bell state as quantum channel with quantum superdence coding, local collective unitary operations, and entanglement swapping. In this protocol, during the process of transmission of particles, the transmitted particles do not carry any secret messages and are transmitted only one time. The protocol has higher source capacity than protocols using symmetric two-dimensional states. The security is ensured by the unitary operations randomly performed on all checking groups before the particle sequence is transmitted and the application of entanglement swapping. (general)
Axially symmetric reconstruction of plasma emission and absorption coefficients
International Nuclear Information System (INIS)
Yang Lixin; Jia Hui; Yang Jiankun; Li Xiujian; Chen Shaorong; Liu Xishun
2013-01-01
A layered structure imaging model is developed in order to reconstruct emission coefficients and absorption coefficients simultaneously, in laser fusion core plasma diagnostics. A novel axially symmetric reconstruction method that utilizes the LM (Levenberg-Marquardt) nonlinear least squares minimization algorithm is proposed based on the layered structure. Numerical simulation results demonstrate that the proposed method is sufficiently accurate to reconstruct emission coefficients and absorption coefficients, and when the standard deviation of noise is 0.01, the errors of emission coefficients and absorption coefficients are 0.17, 0.22, respectively. Furthermore, this method could perform much better on reconstruction effect compared with traditional inverse Abel transform algorithms. (authors)
Asymmetrical and symmetrical embedded Z-source inverters
DEFF Research Database (Denmark)
Gao, F.; Loh, P.C.; Li, D.
2011-01-01
ends, which indirectly translates to a lowering of overall system cost. These noted advantages are indeed appropriate for applications like photovoltaic and fuel cell energy harnessing, and have already been confirmed in simulation and experimentally using a laboratory-implemented inverter prototype.......This study presents two types of embedded Z-source inverters with each type further divided into asymmetrical and symmetrical realisations. Being different from their traditional counterparts, the presented inverters have their dc sources inserted within their X-shaped impedance networks so...
The classification of static plane-symmetric spacetimes
International Nuclear Information System (INIS)
Ziad, M.
1999-01-01
According to the classical literature, here a complete classification of static plane-symmetric spacetimes according to their isometries and metrics is provided,without imposing any restriction on the stress-energy tensor. It turns out that these spacetimes admit G r as the maximal isometry groups whereas their Killing vector fields are obtained. The Einstein field equations are used to discuss the stress energy tensors of the spacetimes admitting higher symmetries along with their Segre' and Plebanski types and finally results are compared with those of Taub, Hall and Steele
The rationality of EIA forecasts under symmetric and asymmetric loss
Energy Technology Data Exchange (ETDEWEB)
Auffhammer, Maximilian [Department of Agricultural and Resource Economics, University of California, 207 Giannini Hall 3310, Berkeley, CA 94720 (United States)
2007-05-15
The United States Energy Information Administration publishes annual forecasts of nationally aggregated energy consumption, production, prices, intensity and GDP. These government issued forecasts often serve as reference cases in the calibration of simulation and econometric models, which climate and energy policy are based on. This study tests for rationality of published EIA forecasts under symmetric and asymmetric loss. We find strong empirical evidence of asymmetric loss for oil, coal and electricity prices as well as natural gas consumption, electricity sales, GDP and energy intensity. (author)
Symmetric reconfigurable capacity assignment in a bidirectional DWDM access network.
Ortega, Beatriz; Mora, José; Puerto, Gustavo; Capmany, José
2007-12-10
This paper presents a novel architecture for DWDM bidirectional access networks providing symmetric dynamic capacity allocation for both downlink and uplink signals. A foldback arrayed waveguide grating incorporating an optical switch enables the experimental demonstration of flexible assignment of multiservice capacity. Different analog and digital services, such as CATV, 10 GHz-tone, 155Mb/s PRBS and UMTS signals have been transmitted in order to successfully test the system performance under different scenarios of total capacity distribution from the Central Station to different Base Stations with two reconfigurable extra channels for each down and upstream direction.
Numerical study of two-dimensional moist symmetric instability
Directory of Open Access Journals (Sweden)
M. Fantini
2008-06-01
Full Text Available The 2-D version of the non-hydrostatic fully compressible model MOLOCH developed at ISAC-CNR was used in idealized set-up to study the start-up and finite amplitude evolution of symmetric instability. The unstable basic state was designed by numerical integration of the equation which defines saturated equivalent potential vorticity q_{e}^{*}. We present the structure and growth rates of the linear modes both for a supersaturated initial state ("super"-linear mode and for a saturated one ("pseudo"-linear mode and the modifications induced on the base state by their finite amplitude evolution.
Electromagnetically Induced Transparency in Symmetric Planar Metamaterial at THz Wavelengths
Directory of Open Access Journals (Sweden)
Abdelwaheb Ourir
2015-03-01
Full Text Available We report the experimental observation and the evidence of the analogue of electromagnetically-induced transparency (EIT in a symmetric planar metamaterial. This effect has been obtained in the THz range thanks to a destructive Fano-interference between the two first modes of an array of multi-gap split ring resonators deposited on a silicon substrate. This structure is a planar thin film material with four-fold symmetry. Thanks to this property, a polarization-independent transmission has been achieved. The proposed metamaterial is well adapted to variety of slow-light applications in the infrared and optical range.
Breaking the symmetry of a Brownian motor with symmetric potentials
International Nuclear Information System (INIS)
Hagman, H; Zelan, M; Dion, C M
2011-01-01
The directed transport of Brownian particles requires a system with an asymmetry and with non-equilibrium noise. Here we investigate numerically alternative ways of fulfilling these requirements for a two-state Brownian motor, realized with Brownian particles alternating between two phase-shifted, symmetric potentials. We show that, besides the previously known spatio-temporal asymmetry based on unequal transfer rates between the potentials, inequalities in the potential depths, the frictions, or the equilibrium temperatures of the two potentials also generate the required asymmetry. We also show that the effects of the thermal noise and the noise of the transfer's randomness depend on the way the asymmetry is induced.
Diagonalization of the symmetrized discrete i th right shift operator
Fuentes, Marc
2007-01-01
In this paper, we consider the symmetric part of the so-called ith right shift operator. We determine its eigenvalues as also the associated eigenvectors in a complete and closed form. The proposed proof is elementary, using only basical skills such as Trigonometry, Arithmetic and Linear algebra. The first section is devoted to the introduction of the tackled problem. Second and third parts contain almost all the ?technical? stuff of the proofE Afterwards, we continue with the end of the proof, provide a graphical illustration of the results, as well as an application on the polyhedral ?sandwiching? of a special compact of arising in Signal theory.
Helically symmetric equilibria with pressure anisotropy and incompressible plasma flow
Evangelias, A.; Kuiroukidis, A.; Throumoulopoulos, G. N.
2018-02-01
We derive a generalized Grad-Shafranov equation governing helically symmetric equilibria with pressure anisotropy and incompressible flow of arbitrary direction. Through the most general linearizing ansatz for the various free surface functions involved therein, we construct equilibrium solutions and study their properties. It turns out that pressure anisotropy can act either paramegnetically or diamagnetically, the parallel flow has a paramagnetic effect, while the non-parallel component of the flow associated with the electric field has a diamagnetic one. Also, pressure anisotropy and flow affect noticeably the helical current density.
Integral solution for the spherically symmetric Fokker-Planck equation
International Nuclear Information System (INIS)
Donoso, J.M.; Soler, M.
1993-01-01
We propose an integral method to deal with the spherically symmetric non-linear Fokker-Planck equation appearing in plasma physics. A probability transition expression is obtained, which takes into account the proper domain for the radial velocity component. The analytical and computational results are new, and the time evolution is completely satisfactory. The main achievement of the method is conservation of both the initial norm and energy for unlimited times, which has not been attained in the differential approach to the problem. (orig.)
A Searchable Symmetric Encryption Scheme using BlockChain
Li, Huige; Zhang, Fangguo; He, Jiejie; Tian, Haibo
2017-01-01
At present, the cloud storage used in searchable symmetric encryption schemes (SSE) is provided in a private way, which cannot be seen as a true cloud. Moreover, the cloud server is thought to be credible, because it always returns the search result to the user, even they are not correct. In order to really resist this malicious adversary and accelerate the usage of the data, it is necessary to store the data on a public chain, which can be seen as a decentralized system. As the increasing am...
Entanglement Classification of extended Greenberger-Horne-Zeilinger-Symmetric States
Jung, Eylee; Park, DaeKil
2013-01-01
In this paper we analyze entanglement classification of extended Greenberger-Horne-Zeilinger-symmetric states $\\rho^{ES}$, which is parametrized by four real parameters $x$, $y_1$, $y_2$ and $y_3$. The condition for separable states of $\\rho^{ES}$ is analytically derived. The higher classes such as bi-separable, W, and Greenberger-Horne-Zeilinger classes are roughly classified by making use of the class-specific optimal witnesses or map from the extended Greenberger-Horne-Zeilinger symmetry t...
Symmetric fusion of heavy ions around the Coulomb barrier energy
International Nuclear Information System (INIS)
Royer, G.; Remaud, B.
1983-01-01
Using the liquid drop model, we have performed a systematic study of the symmetric fusion with a neck degree of freedom and tunnelling effects, the nuclear potential being calculated with the proximity approach. Barrier heights and positions are in very good agreement with experimental data when they are known (light-medium systems); the recent experimental data of the reactions 58 Ni + 58 Ni and 64 Ni + 64 Ni are particularly investigated. For heavier systems double-humped fusion barriers and isomeric states are predicted which strongly limit the complete fusion probability
Elliptic Genera of Symmetric Products and Second Quantized Strings
Dijkgraaf, R; Verlinde, Erik; Verlinde, Herman L
1997-01-01
In this note we prove an identity that equates the elliptic genus partition function of a supersymmetric sigma model on the $N$-fold symmetric product $M^N/S_N$ of a manifold $M$ to the partition function of a second quantized string theory on the space $M \\times S^1$. The generating function of these elliptic genera is shown to be (almost) an automorphic form for $O(3,2,\\Z)$. In the context of D-brane dynamics, this result gives a precise computation of the free energy of a gas of D-strings inside a higher-dimensional brane.
Quasi-single helicity spectra in the Madison Symmetric Torus
International Nuclear Information System (INIS)
Marrelli, L.; Martin, P.; Spizzo, G.; Franz, P.; Chapman, B.E.; Craig, D.; Sarff, J.S.; Biewer, T.M.; Prager, S.C.; Reardon, J.C.
2002-01-01
Evidence of a self-organized collapse towards a narrow spectrum of magnetic instabilities in the Madison Symmetric Torus [R. N. Dexter, D. W. Kerst, T. W. Lovell, S. C. Prager, and J. C. Sprott, Fusion Technol. 19, 131 (1991)] reversed field pinch device is presented. In this collapsed state, dubbed quasi-single helicity (QSH), the spectrum of magnetic modes condenses spontaneously to one dominant mode more completely than ever before observed. The amplitudes of all but the largest of the m=1 modes decrease in QSH states. New results about thermal features of QSH spectra and the identification of global control parameters for their onset are also discussed
Constructing quantum games from symmetric non-factorizable joint probabilities
International Nuclear Information System (INIS)
Chappell, James M.; Iqbal, Azhar; Abbott, Derek
2010-01-01
We construct quantum games from a table of non-factorizable joint probabilities, coupled with a symmetry constraint, requiring symmetrical payoffs between the players. We give the general result for a Nash equilibrium and payoff relations for a game based on non-factorizable joint probabilities, which embeds the classical game. We study a quantum version of Prisoners' Dilemma, Stag Hunt, and the Chicken game constructed from a given table of non-factorizable joint probabilities to find new outcomes in these games. We show that this approach provides a general framework for both classical and quantum games without recourse to the formalism of quantum mechanics.
Feature Surfaces in Symmetric Tensor Fields Based on Eigenvalue Manifold.
Palacios, Jonathan; Yeh, Harry; Wang, Wenping; Zhang, Yue; Laramee, Robert S; Sharma, Ritesh; Schultz, Thomas; Zhang, Eugene
2016-03-01
Three-dimensional symmetric tensor fields have a wide range of applications in solid and fluid mechanics. Recent advances in the (topological) analysis of 3D symmetric tensor fields focus on degenerate tensors which form curves. In this paper, we introduce a number of feature surfaces, such as neutral surfaces and traceless surfaces, into tensor field analysis, based on the notion of eigenvalue manifold. Neutral surfaces are the boundary between linear tensors and planar tensors, and the traceless surfaces are the boundary between tensors of positive traces and those of negative traces. Degenerate curves, neutral surfaces, and traceless surfaces together form a partition of the eigenvalue manifold, which provides a more complete tensor field analysis than degenerate curves alone. We also extract and visualize the isosurfaces of tensor modes, tensor isotropy, and tensor magnitude, which we have found useful for domain applications in fluid and solid mechanics. Extracting neutral and traceless surfaces using the Marching Tetrahedra method can cause the loss of geometric and topological details, which can lead to false physical interpretation. To robustly extract neutral surfaces and traceless surfaces, we develop a polynomial description of them which enables us to borrow techniques from algebraic surface extraction, a topic well-researched by the computer-aided design (CAD) community as well as the algebraic geometry community. In addition, we adapt the surface extraction technique, called A-patches, to improve the speed of finding degenerate curves. Finally, we apply our analysis to data from solid and fluid mechanics as well as scalar field analysis.
Analysis of generic insertions made of two symmetric triplets
D'Amico, T E
1998-01-01
This paper reports on the study undertaken to explore the capabilities of a symmetric triplet to achieve the optics constraints required by the inner triplet of an insertion and more generally of a co mplete insertion made of two symmetric triplets to match a double focus to a FODO lattice. It is based on analytical treatment formulating a number of constraints equal to the parameters available. Th is thorough and systematic analysis made it possible to establish for an inner triplet as well as for a complete insertion the existence of solutions and to explicitly find out all the solutions, with out resorting to unguided numerical searches. As a by-product, a lattice transformer, made of a single triplet, that matches two different FODO cells has been singled out and studied in details. The r esults should be profitable in a number of cases. Here, the method is applied to an insertion of the type of an experimental LHC insertion in order to investigate its domain of validity and tunability .
Cylindrically symmetric Fresnel lens for high concentration photovoltaic
Hung, Yu-Ting; Su, Guo-Dung
2009-08-01
High concentration photovoltaic (HCPV) utilizes point-focus cost-effective plastic Fresnel lens. And a millimeter-sized Ill-V compound multi-junction solar cell is placed underneath focusing optics which can achieve cell efficiency potential of up to 40.7 %. The advantage of HCPV makes less solar cell area and higher efficiency; however, the acceptance angle of HCPV is about +/-1°, which is very small and the mechanical tracking of the sun is necessary. In order to reduce the power consumption and the angle tracking error of tracking systems, a light collector model with larger acceptance angle is designed with ZEMAXÂ®. In this model, the original radially symmetric Fresnel lens of HCPV is replaced by cylindrically symmetric Fresnel lens and a parabolic reflective surface. Light is collected in two dimensions separately. And a couple of lenses and a light pipe are added before the solar cell chip in order to collect more light when sun light deviates from incident angle of 00. An acceptance angle of +/-10° is achieved with GCR 400.
The theory of spherically symmetric thin shells in conformal gravity
Berezin, Victor; Dokuchaev, Vyacheslav; Eroshenko, Yury
The spherically symmetric thin shells are the nearest generalizations of the point-like particles. Moreover, they serve as the simple sources of the gravitational fields both in General Relativity and much more complex quadratic gravity theories. We are interested in the special and physically important case when all the quadratic in curvature tensor (Riemann tensor) and its contractions (Ricci tensor and scalar curvature) terms are present in the form of the square of Weyl tensor. By definition, the energy-momentum tensor of the thin shell is proportional to Diracs delta-function. We constructed the theory of the spherically symmetric thin shells for three types of gravitational theories with the shell: (1) General Relativity; (2) Pure conformal (Weyl) gravity where the gravitational part of the total Lagrangian is just the square of the Weyl tensor; (3) Weyl-Einstein gravity. The results are compared with these in General Relativity (Israel equations). We considered in detail the shells immersed in the vacuum. Some peculiar properties of such shells are found. In particular, for the traceless ( = massless) shell, it is shown that their dynamics cannot be derived from the matching conditions and, thus, is completely arbitrary. On the contrary, in the case of the Weyl-Einstein gravity, the trajectory of the same type of shell is completely restored even without knowledge of the outside solution.
Sirius-T, a symmetrically illuminated ICF tritium production facility
International Nuclear Information System (INIS)
Sviatoslavsky, I.N.; Sawan, M.E.; Moses, G.A.; Kulcinski, G.L.; Engelstad, R.L.; Larsen, E.; Lovell, E.; MacFarlane, J.; Peterson, R.R.; Wittenberg, L.J.
1989-01-01
A scoping study of a symmetrically illuminated ICF tritium production facility utilizing a KrF laser is presented. A single shell ICF target is illuminated by 92 beams symmetrically distributed around a spherical cavity filled with xenon gas at 1.0 torr. The driver energy and target gain are taken to be 2 MJ and 50 for the optimistic case and 1 MJ and 100 for the conservative case. Based on a graphite dry wall evaporation rate of 0.1 cm/y for a 100 MJ yield, the authors estimate a cavity radius of 3.5 m for a rep-rate of 10 Hz and 3.0 m for 5 Hz. A spherical structural frame has been scoped out capable of supporting 92 blanket modules, each with a beam port in the center. They have selected liquid lithium in vanadium structure as the primary breeding concept utilizing beryllium as a neutron multiplier. A tritium breeding ratio of 1.83 can be achieved in the 3 m radius cavity which at 10 Hz and an availability of 75% provides an annual tritium surplus of 32.6 kg. Assuming 100% debt financing over a 30 year reactor lifetime, the production cost of T 2 for the 2 MJ driver case is $7,325/g for a 5% interest rate and $12,370/g for a 10% interest rate. 8 refs., 3 figs., 4 tabs
Thermoacoustic focusing lens by symmetric Airy beams with phase manipulations
Liu, Chen; Xia, Jian-Ping; Sun, Hong-Xiang; Yuan, Shou-Qi
2017-12-01
We report the realization of broadband acoustic focusing lenses based on two symmetric thermoacoustic phased arrays of Airy beams, in which the units of thermoacoustic phase control are designed by employing air with different temperatures surrounded by rigid insulated boundaries and thermal insulation films. The phase delays of the transmitted and reflected units could cover a whole 2π interval, which arises from the change of the sound velocity of air induced by the variation of the temperature. Based on the units of phase control, we design the transmitted and reflected acoustic focusing lenses with two symmetric Airy beams, and verify the high self-healing focusing characteristic and the feasibility of the thermal insulation films. Besides, the influences of the bending angle of the Airy beam on the focusing performance are discussed in detail. The proposed acoustic lens has advantages of broad bandwidth (about 4.8 kHz), high focusing performance, self-healing feature, and simple structure, which enable it to provide more schemes for acoustic focusing. It has excellent potential applications in acoustic devices.
The Hall instability of unsteady inhomogeneous axially symmetric magnetized plasmas
International Nuclear Information System (INIS)
Shtemler, Yuri M.; Mond, Michael; Liverts, Edward
2004-01-01
The Hall instability in cylindrically symmetric resistive magnetized plasmas in vacuum is investigated. The unperturbed self-similar equilibrium solutions for imploding Z-pinches with time-dependent total current I t ∼t S ,S>1/3, are subjected by short-wave sausage perturbations. The instability criterion is derived in slow-time, frozen-radius approximation. In cylindrically symmetric configurations the instability is driven by the magnetic field curvature. The near-axis and near-edge branches of the neutral curve in the plane of the inverse Hall parameter and phase velocity with the frozen radial coordinate as a parameter are separated by the critical point, where the modified gradient from the unperturbed number density changes sign. The critical radius may be treated as a new characteristic size of the Z-pinch that emerges due to the instability: the pinch is envisaged restructured by the short-scale high-frequency Hall instability, in which a central stable core is surrounded by an outer shell. Such a modified equilibrium may explain the observed enhanced stability against magnetohydrodynamic modes
WKB analysis of PT-symmetric Sturm–Liouville problems
International Nuclear Information System (INIS)
Bender, Carl M; Jones, Hugh F
2012-01-01
Most studies of PT-symmetric quantum-mechanical Hamiltonians have considered the Schrödinger eigenvalue problem on an infinite domain. This paper examines the consequences of imposing the boundary conditions on a finite domain. As is the case with regular Hermitian Sturm–Liouville problems, the eigenvalues of the PT-symmetric Sturm–Liouville problem grow like n 2 for large n. However, the novelty is that a PT eigenvalue problem on a finite domain typically exhibits a sequence of critical points at which pairs of eigenvalues cease to be real and become complex conjugates of one another. For the potentials considered here this sequence of critical points is associated with a turning point on the imaginary axis in the complex plane. WKB analysis is used to calculate the asymptotic behaviours of the real eigenvalues and the locations of the critical points. The method turns out to be surprisingly accurate even at low energies. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Quantum physics with non-Hermitian operators’. (paper)
Markov Jump Processes Approximating a Non-Symmetric Generalized Diffusion
International Nuclear Information System (INIS)
Limić, Nedžad
2011-01-01
Consider a non-symmetric generalized diffusion X(⋅) in ℝ d determined by the differential operator A(x) = -Σ ij ∂ i a ij (x)∂ j + Σ i b i (x)∂ i . In this paper the diffusion process is approximated by Markov jump processes X n (⋅), in homogeneous and isotropic grids G n ⊂ℝ d , which converge in distribution in the Skorokhod space D([0,∞),ℝ d ) to the diffusion X(⋅). The generators of X n (⋅) are constructed explicitly. Due to the homogeneity and isotropy of grids, the proposed method for d≥3 can be applied to processes for which the diffusion tensor {a ij (x)} 11 dd fulfills an additional condition. The proposed construction offers a simple method for simulation of sample paths of non-symmetric generalized diffusion. Simulations are carried out in terms of jump processes X n (⋅). For piece-wise constant functions a ij on ℝ d and piece-wise continuous functions a ij on ℝ 2 the construction and principal algorithm are described enabling an easy implementation into a computer code.
Spherically symmetric solutions of general second-order gravity
International Nuclear Information System (INIS)
Whitt, B.
1988-01-01
The general second-order gravity theory, whose Lagrangian includes higher powers of the curvature, is considered in arbitrary dimensions. It is shown that spherically symmetric solutions are static, except in certain, special, unphysical cases. Spherically symmetric solutions are found and classified. Each theory's solutions fall into a number of distinct branches, which may represent finite space with two singular boundaries, or an asymptotically either flat or (anti--)de Sitter space with one singular boundary. A theory may contain at most one branch of solutions in which all singularities are hidden by event horizons. Such horizons generally emit Hawking radiation, though in certain cases the horizon may have zero temperature. Black holes do not necessarily radiate away all their mass: they may terminate in a zero-temperature black hole, a naked singularity, or a hot black hole in equilibrium with a ''cosmological'' event horizon. The thermodynamics of black-hole solutions is discussed; entropy is found to be an increasing function of horizon area, and the first law is shown to hold
Non-Archimedean analogues of orthogonal and symmetric operators
International Nuclear Information System (INIS)
Albeverio, S; Bayod, J M; Perez-Garsia, C; Khrennikov, A Yu; Cianci, R
1999-01-01
We study orthogonal and symmetric operators on non-Archimedean Hilbert spaces in connection with the p-adic quantization. This quantization describes measurements with finite precision. Symmetric (bounded) operators on p-adic Hilbert spaces represent physical observables. We study the spectral properties of one of the most important quantum operators, namely, the position operator (which is represented on p-adic Hilbert L 2 -space with respect to the p-adic Gaussian measure). Orthogonal isometric isomorphisms of p-adic Hilbert spaces preserve the precision of measurements. We study properties of orthogonal operators. It is proved that every orthogonal operator on non-Archimedean Hilbert space is continuous. However, there are discontinuous operators with dense domain of definition that preserve the inner product. There exist non-isometric orthogonal operators. We describe some classes of orthogonal isometric operators on finite-dimensional spaces. We study some general questions in the theory of non-Archimedean Hilbert spaces (in particular, general connections between the topology, norm and inner product)
Gout on CT of the feet: A symmetric arthropathy
International Nuclear Information System (INIS)
Doyle, Anthony J.; Boyer, Lucinda; Dong, Jing; Dalbeth, Nicola; McQueen, Fiona; Rome, Keith; Frecklington, Mike
2016-01-01
The aim of this study was to assess the distribution of bone erosions in the feet of patients with gout using CT and thereby to test the hypothesis that gout is an asymmetric arthropathy. CT scans of both feet were obtained from 25 patients with chronic gout. CT scans were scored for bone erosion using a semi-quantitative method based on the rheumatoid arthritis MRI scoring system (RAMRIS). CT bone erosion was assessed at 22 bones in each foot (total 1,100 bones) by two independent radiologists. Symmetry was assessed by two methods: (i) comparing right and left foot scores for each patient; and (ii) calculating the proportion of paired joints with or without erosions. Observer agreement was excellent (intra-class correlation coefficient 0.92). In the group overall, the difference in scores between the feet was not significant (Student's t-test P = 0.8). In 17 of 25 patients, the difference in erosion scores between the two feet was less than the inter-observer difference. In 24 of 25 patients, the proportion of paired joints was greater than 0.5, indicating symmetric disease. Erosive disease from gout is, in fact, a symmetric process in our patient group. This finding is contrary to the established view of gout as an asymmetric arthritis and lends new insight into the behaviour of this common disease.
Separability of diagonal symmetric states: a quadratic conic optimization problem
Directory of Open Access Journals (Sweden)
Jordi Tura
2018-01-01
Full Text Available We study the separability problem in mixtures of Dicke states i.e., the separability of the so-called Diagonal Symmetric (DS states. First, we show that separability in the case of DS in $C^d\\otimes C^d$ (symmetric qudits can be reformulated as a quadratic conic optimization problem. This connection allows us to exchange concepts and ideas between quantum information and this field of mathematics. For instance, copositive matrices can be understood as indecomposable entanglement witnesses for DS states. As a consequence, we show that positivity of the partial transposition (PPT is sufficient and necessary for separability of DS states for $d \\leq 4$. Furthermore, for $d \\geq 5$, we provide analytic examples of PPT-entangled states. Second, we develop new sufficient separability conditions beyond the PPT criterion for bipartite DS states. Finally, we focus on $N$-partite DS qubits, where PPT is known to be necessary and sufficient for separability. In this case, we present a family of almost DS states that are PPT with respect to each partition but nevertheless entangled.
Symmetric Dimethylarginine in Cats with Hypertrophic Cardiomyopathy and Diabetes Mellitus
DEFF Research Database (Denmark)
Langhorn, R.; Kieler, I. N.; Koch, J.
2018-01-01
Background: Symmetric dimethylarginine (SDMA) has been increasingly used as a marker of early chronic kidney disease (CKD) in cats, but little is known about the influence of comorbidities on SDMA in this species. Hypothesis: Hypertrophic cardiomyopathy (HCM) and diabetes mellitus (DM), independe......Background: Symmetric dimethylarginine (SDMA) has been increasingly used as a marker of early chronic kidney disease (CKD) in cats, but little is known about the influence of comorbidities on SDMA in this species. Hypothesis: Hypertrophic cardiomyopathy (HCM) and diabetes mellitus (DM......), independently of CKD, are associated with changes in serum SDMA. Animals: Ninety-four cats (17 with CKD, 40 with HCM, 17 with DM, and 20 healthy controls). Methods: Case-control study. Clinical examination, echocardiography, ECG, blood pressure, CBC, biochemistry, thyroxine, and SDMA measurement were performed....... Urinalysis was performed in controls and cats with CKD and DM. Analysis of variance was used to compare overall differences in the log-transformed SDMA data among groups. A random forest algorithm was applied to explore which clinical and other factors influenced serum SDMA. Results: Median (range) serum...
Closed Form Aliasing Probability For Q-ary Symmetric Errors
Directory of Open Access Journals (Sweden)
Geetani Edirisooriya
1996-01-01
Full Text Available In Built-In Self-Test (BIST techniques, test data reduction can be achieved using Linear Feedback Shift Registers (LFSRs. A faulty circuit may escape detection due to loss of information inherent to data compaction schemes. This is referred to as aliasing. The probability of aliasing in Multiple-Input Shift-Registers (MISRs has been studied under various bit error models. By modeling the signature analyzer as a Markov process we show that the closed form expression derived for aliasing probability previously, for MISRs with primitive polynomials under q-ary symmetric error model holds for all MISRs irrespective of their feedback polynomials and for group cellular automata signature analyzers as well. If the erroneous behaviour of a circuit can be modelled with q-ary symmetric errors, then the test circuit complexity and propagation delay associated with the signature analyzer can be minimized by using a set of m single bit LFSRs without increasing the probability of aliasing.
Spherical aberration correction with threefold symmetric line currents.
Hoque, Shahedul; Ito, Hiroyuki; Nishi, Ryuji; Takaoka, Akio; Munro, Eric
2016-02-01
It has been shown that N-fold symmetric line current (henceforth denoted as N-SYLC) produces 2N-pole magnetic fields. In this paper, a threefold symmetric line current (N3-SYLC in short) is proposed for correcting 3rd order spherical aberration of round lenses. N3-SYLC can be realized without using magnetic materials, which makes it free of the problems of hysteresis, inhomogeneity and saturation. We investigate theoretically the basic properties of an N3-SYLC configuration which can in principle be realized by simple wires. By optimizing the parameters of a system with beam energy of 5.5keV, the required excitation current for correcting 3rd order spherical aberration coefficient of 400 mm is less than 1AT, and the residual higher order aberrations can be kept sufficiently small to obtain beam size of less than 1 nm for initial slopes up to 5 mrad. Copyright © 2015 Elsevier B.V. All rights reserved.
Mixed dark matter in left-right symmetric models
Energy Technology Data Exchange (ETDEWEB)
Berlin, Asher [Department of Physics, University of Chicago,Chicago, Illinois 60637 (United States); Fox, Patrick J. [Theoretical Physics Department, Fermilab,Batavia, Illinois 60510 (United States); Hooper, Dan [Center for Particle Astrophysics, Fermi National Accelerator Laboratory,Batavia, Illinois 60510 (United States); Department of Astronomy and Astrophysics, University of Chicago,Chicago, Illinois 60637 (United States); Mohlabeng, Gopolang [Center for Particle Astrophysics, Fermi National Accelerator Laboratory,Batavia, Illinois 60510 (United States); Department of Physics and Astronomy, University of Kansas,Lawrence, Kansas 66045 (United States)
2016-06-08
Motivated by the recently reported diboson and dijet excesses in Run 1 data at ATLAS and CMS, we explore models of mixed dark matter in left-right symmetric theories. In this study, we calculate the relic abundance and the elastic scattering cross section with nuclei for a number of dark matter candidates that appear within the fermionic multiplets of left-right symmetric models. In contrast to the case of pure multiplets, WIMP-nucleon scattering proceeds at tree-level, and hence the projected reach of future direct detection experiments such as LUX-ZEPLIN and XENON1T will cover large regions of parameter space for TeV-scale thermal dark matter. Decays of the heavy charged W{sup ′} boson to particles in the dark sector can potentially shift the right-handed gauge coupling to larger values when fixed to the rate of the Run 1 excesses, moving towards the theoretically attractive scenario, g{sub R}=g{sub L}. This region of parameter space may be probed by future collider searches for new Higgs bosons or electroweak fermions.
Quantum effects in non-maximally symmetric spaces
International Nuclear Information System (INIS)
Shen, T.C.
1985-01-01
Non-Maximally symmetric spaces provide a more general background to explore the relation between the geometry of the manifold and the quantum fields defined in the manifold than those with maximally symmetric spaces. A static Taub universe is used to study the effect of curvature anisotropy on the spontaneous symmetry breaking of a self-interacting scalar field. The one-loop effective potential on a λphi 4 field with arbitrary coupling xi is computed by zeta function regularization. For massless minimal coupled scalar fields, first order phase transitions can occur. Keeping the shape invariant but decreasing the curvature radius of the universe induces symmetry breaking. If the curvature radius is held constant, increasing deformation can restore the symmetry. Studies on the higher-dimensional Kaluza-Klein theories are also focused on the deformation effect. Using the dimensional regularization, the effective potential of the free scalar fields in M 4 x T/sup N/ and M 4 x (Taub) 3 spaces are obtained. The stability criterions for the static solutions of the self-consistent Einstein equations are derived. Stable solutions of the M 4 x S/sup N/ topology do not exist. With the Taub space as the internal space, the gauge coupling constants of SU(2), and U(1) can be determined geometrically. The weak angle is therefore predicted by geometry in this model
An Efficient Quantum Somewhat Homomorphic Symmetric Searchable Encryption
Sun, Xiaoqiang; Wang, Ting; Sun, Zhiwei; Wang, Ping; Yu, Jianping; Xie, Weixin
2017-04-01
In 2009, Gentry first introduced an ideal lattices fully homomorphic encryption (FHE) scheme. Later, based on the approximate greatest common divisor problem, learning with errors problem or learning with errors over rings problem, FHE has developed rapidly, along with the low efficiency and computational security. Combined with quantum mechanics, Liang proposed a symmetric quantum somewhat homomorphic encryption (QSHE) scheme based on quantum one-time pad, which is unconditional security. And it was converted to a quantum fully homomorphic encryption scheme, whose evaluation algorithm is based on the secret key. Compared with Liang's QSHE scheme, we propose a more efficient QSHE scheme for classical input states with perfect security, which is used to encrypt the classical message, and the secret key is not required in the evaluation algorithm. Furthermore, an efficient symmetric searchable encryption (SSE) scheme is constructed based on our QSHE scheme. SSE is important in the cloud storage, which allows users to offload search queries to the untrusted cloud. Then the cloud is responsible for returning encrypted files that match search queries (also encrypted), which protects users' privacy.
Conservation laws in baroclinic inertial-symmetric instabilities
Grisouard, Nicolas; Fox, Morgan B.; Nijjer, Japinder
2017-04-01
Submesoscale oceanic density fronts are structures in geostrophic and hydrostatic balance, but are more prone to instabilities than mesoscale flows. As a consequence, they are believed to play a large role in air-sea exchanges, near-surface turbulence and dissipation of kinetic energy of geostrophically and hydrostatically balanced flows. We will present two-dimensional (x, z) Boussinesq numerical experiments of submesoscale baroclinic fronts on the f-plane. Instabilities of the mixed inertial and symmetric types (the actual name varies across the literature) develop, with the absence of along-front variations prohibiting geostrophic baroclinic instabilities. Two new salient facts emerge. First, contrary to pure inertial and/or pure symmetric instability, the potential energy budget is affected, the mixed instability extracting significant available potential energy from the front and dissipating it locally. Second, in the submesoscale regime, the growth rate of this mixed instability is sufficiently large that significant radiation of near-inertial internal waves occurs. Although energetically small compared to e.g. local dissipation within the front, this process might be a significant source of near-inertial energy in the ocean.
Characteristic function-based semiparametric inference for skew-symmetric models
Potgieter, Cornelis J.
2012-12-26
Skew-symmetric models offer a very flexible class of distributions for modelling data. These distributions can also be viewed as selection models for the symmetric component of the specified skew-symmetric distribution. The estimation of the location and scale parameters corresponding to the symmetric component is considered here, with the symmetric component known. Emphasis is placed on using the empirical characteristic function to estimate these parameters. This is made possible by an invariance property of the skew-symmetric family of distributions, namely that even transformations of random variables that are skew-symmetric have a distribution only depending on the symmetric density. A distance metric between the real components of the empirical and true characteristic functions is minimized to obtain the estimators. The method is semiparametric, in that the symmetric component is specified, but the skewing function is assumed unknown. Furthermore, the methodology is extended to hypothesis testing. Two tests for a hypothesis of specific parameter values are considered, as well as a test for the hypothesis that the symmetric component has a specific parametric form. A resampling algorithm is described for practical implementation of these tests. The outcomes of various numerical experiments are presented. © 2012 Board of the Foundation of the Scandinavian Journal of Statistics.
Extension of PT-symmetric quantum mechanics to quantum field theory with cubic interaction
International Nuclear Information System (INIS)
Bender, Carl M.; Brody, Dorje C.; Jones, Hugh F.
2004-01-01
It has recently been shown that a non-Hermitian Hamiltonian H possessing an unbroken PT symmetry (i) has a real spectrum that is bounded below, and (ii) defines a unitary theory of quantum mechanics with positive norm. The proof of unitarity requires a linear operator C, which was originally defined as a sum over the eigenfunctions of H. However, using this definition to calculate C is cumbersome in quantum mechanics and impossible in quantum field theory. An alternative method is devised here for calculating C directly in terms of the operator dynamical variables of the quantum theory. This method is general and applies to a variety of quantum mechanical systems having several degrees of freedom. More importantly, this method is used to calculate the C operator in quantum field theory. The C operator is a time-independent observable in PT-symmetric quantum field theory
Dynamic Symmetric Key Mobile Commerce Scheme Based on Self-Verified Mechanism
Directory of Open Access Journals (Sweden)
Jiachen Yang
2014-01-01
Full Text Available In terms of the security and efficiency of mobile e-commerce, the authors summarized the advantages and disadvantages of several related schemes, especially the self-verified mobile payment scheme based on the elliptic curve cryptosystem (ECC and then proposed a new type of dynamic symmetric key mobile commerce scheme based on self-verified mechanism. The authors analyzed the basic algorithm based on self-verified mechanisms and detailed the complete transaction process of the proposed scheme. The authors analyzed the payment scheme based on the security and high efficiency index. The analysis shows that the proposed scheme not only meets the high efficiency of mobile electronic payment premise, but also takes the security into account. The user confirmation mechanism at the end of the proposed scheme further strengthens the security of the proposed scheme. In brief, the proposed scheme is more efficient and practical than most of the existing schemes.
Robust Solvers for Symmetric Positive Definite Operators and Weighted Poincaré Inequalities
Efendiev, Yalchin
2012-01-01
An abstract setting for robustly preconditioning symmetric positive definite (SPD) operators is presented. The term "robust" refers to the property of the condition numbers of the preconditioned systems being independent of mesh parameters and problem parameters. Important instances of such problem parameters are in particular (highly varying) coefficients. The method belongs to the class of additive Schwarz preconditioners. The paper gives an overview of the results obtained in a recent paper by the authors. It, furthermore, focuses on the importance of weighted Poincaré inequalities, whose notion is extended to general SPD operators, for the analysis of stable decompositions. To demonstrate the applicability of the abstract preconditioner the scalar elliptic equation and the stream function formulation of Brinkman\\'s equations in two spatial dimensions are considered. Several numerical examples are presented. © 2012 Springer-Verlag.
Higher spins tunneling from a time dependent and spherically symmetric black hole
International Nuclear Information System (INIS)
Siahaan, Haryanto M.
2016-01-01
The discussions of Hawking radiation via tunneling method have been performed extensively in the case of scalar particles. Moreover, there are also several works in discussing the tunneling method for Hawking radiation by using higher spins, e.g. neutrino, photon, and gravitino, in the background of static black holes. Interestingly, it is found that the Hawking temperature for static black holes using the higher spins particles has no difference compared to the one computed using scalars. In this paper, we study the Hawking radiation for a spherically symmetric and time dependent black holes using the tunneling of Dirac particles, photon, and gravitino. We find that the obtained Hawking temperature is similar to the one derived in the tunneling method by using scalars. (orig.)
Higher spins tunneling from a time dependent and spherically symmetric black hole
Energy Technology Data Exchange (ETDEWEB)
Siahaan, Haryanto M. [Parahyangan Catholic University, Physics Department, Bandung (Indonesia)
2016-03-15
The discussions of Hawking radiation via tunneling method have been performed extensively in the case of scalar particles. Moreover, there are also several works in discussing the tunneling method for Hawking radiation by using higher spins, e.g. neutrino, photon, and gravitino, in the background of static black holes. Interestingly, it is found that the Hawking temperature for static black holes using the higher spins particles has no difference compared to the one computed using scalars. In this paper, we study the Hawking radiation for a spherically symmetric and time dependent black holes using the tunneling of Dirac particles, photon, and gravitino. We find that the obtained Hawking temperature is similar to the one derived in the tunneling method by using scalars. (orig.)
A new model for spherically symmetric charged compact stars of embedding class 1
Energy Technology Data Exchange (ETDEWEB)
Maurya, S.K. [University of Nizwa, Department of Mathematical and Physical Sciences, College of Arts and Science, Nizwa (Oman); Gupta, Y.K. [Raj Kumar Goel Institute of Technology, Department of Mathematics, Ghaziabad, U.P. (India); Ray, Saibal [Government College of Engineering and Ceramic Technology, Department of Physics, Kolkata, West Bengal (India); Deb, Debabrata [Indian Institute of Engineering Science and Technology, Department of Physics, Howrah, West Bengal (India)
2017-01-15
In the present study we search for a new stellar model with spherically symmetric matter and a charged distribution in a general relativistic framework. The model represents a compact star of embedding class 1. The solutions obtained here are general in nature, having the following two features: first of all, the metric becomes flat and also the expressions for the pressure, energy density, and electric charge become zero in all the cases if we consider the constant A = 0, which shows that our solutions represent the so-called 'electromagnetic mass model' [17], and, secondly, the metric function ν(r), for the limit n tending to infinity, converts to ν(r) = Cr{sup 2}+ ln B, which is the same as considered by Maurya et al. [11]. We have investigated several physical aspects of the model and find that all the features are acceptable within the requirements of contemporary theoretical studies and observational evidence. (orig.)
Order-disorder transformations in the Σ3 (111)/[110] symmetrical tilt boundary in tungsten
International Nuclear Information System (INIS)
Wang, G.J.; Vitek, V.
1996-01-01
The structure of the Σ3 (111)/[110] symmetrical tilt boundary in tungsten was modeled by molecular statics using Finnis-Sinclair type many body potentials. Several multiple structures have been found which are composed of two types of structural units and the interaction energy between these units is negative. Hence, order-disorder structural transitions may occur in the boundary with structures being ordered and/or disordered mixtures of the two units. the transition temperature is found to be 1,158 K if only the internal energy and configurational entropy are included when evaluating the free energy. However, the transition temperature is 782 K if the vibrational entropy is also incorporated. This demonstrates that the vibrational contribution to the entropy may be as important as the configurational contribution when considering the interfacial transformations
Rovibrational Interaction and Vibrational Constants of the Symmetric Top Molecule 14NF3
Directory of Open Access Journals (Sweden)
Hamid Najib
2013-01-01
Full Text Available Several accurate experimental values of the and rotation-vibration interaction parameters and , , and vibrational constants have been extracted from the most recent high-resolution Fourier transform infrared, millimeter wave, and centimeter wave investigations in the spectra of the oblate symmetric top molecule 14NF3. The band-centres used are those of the four fundamental, the overtones, the combination, and hot bands identified in the region between 400 cm−1 and 2000 cm−1. Comparison of our constants with the ones measured previously, by infrared spectroscopy at low resolution, reveals orders of magnitude higher accuracy of the new values. The agreement between our values and those determined by ab initio calculations employing the TZ2Pf basis is excellent.
Separation of variables in anisotropic models and non-skew-symmetric elliptic r-matrix
Skrypnyk, Taras
2017-05-01
We solve a problem of separation of variables for the classical integrable hamiltonian systems possessing Lax matrices satisfying linear Poisson brackets with the non-skew-symmetric, non-dynamical elliptic so(3)⊗ so(3)-valued classical r-matrix. Using the corresponding Lax matrices, we present a general form of the "separating functions" B( u) and A( u) that generate the coordinates and the momenta of separation for the associated models. We consider several examples and perform the separation of variables for the classical anisotropic Euler's top, Steklov-Lyapunov model of the motion of anisotropic rigid body in the liquid, two-spin generalized Gaudin model and "spin" generalization of Steklov-Lyapunov model.
Effects of symmetrical voltage sags on squirrel-cage induction motors
Energy Technology Data Exchange (ETDEWEB)
Pedra, Joaquin; Sainz, Luis; Corcoles, Felipe [Department of Electrical Engineering, ETSEIB-UPC, Av. Diagonal, 647, 08028 Barcelona (Spain)
2007-10-15
This paper analyzes the symmetrical voltage sag consequences on the induction motor behavior when single- and double-cage models are considered, namely current and torque peaks, and speed loss. These effects depend on several variables like sag type, duration and depth. Voltage sag effects are studied by using single- and double-cage models for three motors of different rated power. The double-cage model always predicts torque and current peaks higher than those of the single-cage model. The single-cage model predicts that voltage sags can produce motor instability, whereas the double-cage model is always stable. Therefore, the double-cage model must be used for the simulation of the squirrel-cage induction motor, because the single-cage model can give erroneous results in some situations. (author)
Charge-exchange QRPA with the Gogny Force for Axially-symmetric Deformed Nuclei
Energy Technology Data Exchange (ETDEWEB)
Martini, M., E-mail: martini.marco@gmail.com [Institut d' Astronomie et d' Astrophysique, Université Libre de Bruxelles, CP-226, 1050 Brussels (Belgium); CEA, DAM, DIF, F-91297 Arpajon (France); Goriely, S. [Institut d' Astronomie et d' Astrophysique, Université Libre de Bruxelles, CP-226, 1050 Brussels (Belgium); Péru, S. [CEA, DAM, DIF, F-91297 Arpajon (France)
2014-06-15
In recent years fully consistent quasiparticle random-phase approximation (QRPA) calculations using finite range Gogny force have been performed to study electromagnetic excitations of several axially-symmetric deformed nuclei up to the {sup 238}U. Here we present the extension of this approach to the charge-exchange nuclear excitations (pnQRPA). In particular we focus on the Isobaric Analog and Gamow-Teller resonances. A comparison of the predicted GT strength distribution with existing experimental data is presented. The role of nuclear deformation is shown. Special attention is paid to β-decay half-lives calculations for which experimental data exist and for specific isotone chains of relevance for the r-process nucleosynthesis.
Topologically protected bound states in photonic parity-time-symmetric crystals.
Weimann, S; Kremer, M; Plotnik, Y; Lumer, Y; Nolte, S; Makris, K G; Segev, M; Rechtsman, M C; Szameit, A
2017-04-01
Parity-time (PT)-symmetric crystals are a class of non-Hermitian systems that allow, for example, the existence of modes with real propagation constants, for self-orthogonality of propagating modes, and for uni-directional invisibility at defects. Photonic PT-symmetric systems that also support topological states could be useful for shaping and routing light waves. However, it is currently debated whether topological interface states can exist at all in PT-symmetric systems. Here, we show theoretically and demonstrate experimentally the existence of such states: states that are localized at the interface between two topologically distinct PT-symmetric photonic lattices. We find analytical closed form solutions of topological PT-symmetric interface states, and observe them through fluorescence microscopy in a passive PT-symmetric dimerized photonic lattice. Our results are relevant towards approaches to localize light on the interface between non-Hermitian crystals.
Investigation of Universal Behavior in Symmetric Diblock Copolymer Melts
Medapuram, Pavani
Coarse-grained theories of dense polymer liquids such as block copolymer melts predict a universal dependence of equilibrium properties on a few dimensionless parameters. For symmetric diblock copolymer melts, such theories predict a universal dependence on only chieN and N¯, where chie is an effective interaction parameter, N is the degree of polymerization, and N¯ is a measure of overlap. This thesis focuses on testing the universal behavior hypothesis by comparing results for various properties obtained from different coarse-grained simulation models to each other. Specifically, results from pairs of simulations of different models that have been designed to have matched values of N¯ are compared over a range of values of chiN. The use of vastly different simulation models allows us to cover a vast range of chi eN ≃ 200 - 8000 that includes most of the experimentally relevant range. Properties studied here include collective and single-chain correlations in the disordered phase, block and chain radii of gyration in the disordered phase, the value of chieN at the order-disorder transition (ODT), the free energy per chain, the latent heat of transition, the layer spacing, the composition profile, and compression modulus in the ordered phase. All results strongly support the universal scaling hypothesis, even for rather short chains, confirming that it is indeed possible to give an accurate universal description of simulation models that differ in many details. The underlying universality becomes apparent, however, only if data are analyzed using an adequate estimate of chie, which we obtained by fitting the structure factor S( q) in the disordered state to predictions of the recently developed renormalized one-loop (ROL) theory. The ROL theory is shown to provide an excellent description of the dependence of S(q on chain length and thermodynamic conditions for all models, even for very short chains, if we allow for the existence of a nonlinear dependence of
Symmetric webs, Jones-Wenzl recursions and q-Howe duality
DEFF Research Database (Denmark)
Rose, David; Tubbenhauer, Daniel
We define and study the category of symmetric sl2-webs. This category is a combinatorial description of the category of all finite dimensional quantum sl2-modules. Explicitly, we show that (the additive closure of) the symmetric sl2-spider is (braided monoidally) equivalent to the latter. Our mai...... tool is a quantum version of symmetric Howe duality. As a corollary of our construction, we provide new insight into Jones-Wenzl projectors and the colored Jones polynomials....
Nurdiyanto, Heri; Rahim, Robbi; Wulan, Nur
2017-12-01
Symmetric type cryptography algorithm is known many weaknesses in encryption process compared with asymmetric type algorithm, symmetric stream cipher are algorithm that works on XOR process between plaintext and key, to improve the security of symmetric stream cipher algorithm done improvisation by using Triple Transposition Key which developed from Transposition Cipher and also use Base64 algorithm for encryption ending process, and from experiment the ciphertext that produced good enough and very random.
Hypercyclic operators on algebra of symmetric snalytic functions on $\\ell_p$
Directory of Open Access Journals (Sweden)
Z. H. Mozhyrovska
2016-06-01
Full Text Available In the paper, it is proposed a method of construction of hypercyclic composition operators on $H(\\mathbb{C}^n$ using polynomial automorphisms of $\\mathbb{C}^n$ and symmetric analytic functions on $\\ell_p.$ In particular, we show that an ``symmetric translation'' operator is hypercyclic on a Frechet algebra of symmetric entire functions on $\\ell_p$ which are bounded on bounded subsets.
Information entropy for static spherically symmetric black holes
Institute of Scientific and Technical Information of China (English)
Jiang Ji-Jian; Li Chuan-An
2009-01-01
By using the new equation of state density derived from the generalized uncertainty relation, the number of the quantum states near event horizon is obtained, with which then the information entropy of static spherically symmetric black holes has been discussed. It is found that the divergent integral of quantum states near the event horizon can be naturally avoided if using the new equation of state density without introducing the ultraviolet cut-off. The information entropy of black holes can be obtained precisely by the residue theorem, which is shown to be proportional to the horizon area. The information entropy of black holes obtained agrees with the Bechenstein-Hawking entropy when the suitable cutoff factor is adopted.
Notes on entropy force in general spherically symmetric spacetimes
International Nuclear Information System (INIS)
Cai Ronggen; Cao Liming; Ohta, Nobuyoshi
2010-01-01
In a recent paper [arXiv:1001.0785], Verlinde has shown that the Newton gravity appears as an entropy force. In this paper we show how gravity appears as entropy force in Einstein's equation of gravitational field in a general spherically symmetric spacetime. We mainly focus on the trapping horizon of the spacetime. We find that when matter fields are absent, the change of entropy associated with the trapping horizon indeed can be identified with an entropy force. When matter fields are present, we see that heat flux of matter fields also leads to the change of entropy. Applying arguments made by Verlinde and Smolin, respectively, to the trapping horizon, we find that the entropy force is given by the surface gravity of the horizon. The cases in the untrapped region of the spacetime are also discussed.
Directory of Open Access Journals (Sweden)
Omar Alsaed
2018-06-01
Full Text Available The most common cause of bilateral symmetrical polyarthritis in the small joints is rheumatoid arthritis. However, if seronegative arthritis is involved, it could be the case that other underlying causes need to be diagnosed. This is particularly important for those coming from or living in developing countries where infectious causes should always be considered. The case of a young Nepali woman is presented in this article. She was referred as a case of seronegative rheumatoid arthritis for DMARDs therapy but this was not the case due to her origin from Nepal and seronegativity for RF, Anti-ccp, and ANA as well as faint macular skin lesions over her face and upper extremities, which the patients are not aware of. Consequently, skin biopsy was carried out which subsequently confirmed that the infectious cause of her polyarthritis was leprosy.
Multiple Symmetric Lipomatosis: A Review of 3 Cases
Directory of Open Access Journals (Sweden)
Emilio Mevio
2012-01-01
Full Text Available Multiple symmetrical lipomatosis, or Madelung's disease, is a rare disease of unknown etiology. It is characterized by the presence of loose adipose tissue deposits localized in the cervical region and in the upper body. The neoformations grow slowly and their initial consequence is purely esthetic. They can, however, lead to compression of the laryngotacheal area and of the esophagus. This disease usually affects middle-aged males from the Mediterranean area with a history of alcohol abuse. Although most cases have been sporadic, a few authors have indicated that the disorder may be hereditary. It is thought that this pathology originates from an alteration in lipid metabolism. Since the patients were asymptomatic temperance and diet was proposed, surgical removal of the lipomatose mass is the treatment of choice in case of complications due to fat mass compression on upper aerodigestive tract. The authors present three cases of Madelung's disease with different and particular manifestations.
Manifest rotation symmetric expressions for angular momentum eigenfunctions
International Nuclear Information System (INIS)
Eeg, J.O.; Wroldsen, J.
1983-01-01
Manifest rotation symmetric expressions for eigenfunctions for spin s, orbital angular momentum l and total angular momentum j = l+s, .... , /l-s/ in terms of (2j+1) x (2s+1) multipole transition matrices (MTM) is given. These matrices, which are irreducible tensor matrices, have an algebra together with ordinary spin matrices for spin s and spin j. Explicit expressions for MTM's and their algebra are given for angular momenta <-3. By means of some examples it is shown that within this formalism angular integrations in central field problems will be simplified considerably. Thus the formalism turns out to be very useful for instance for calculations within the MIT-bag and also within spin-spin interactions in atomic physics. (Auth.)
Spherically symmetric solutions in abelian Kaluza-Klein theories
International Nuclear Information System (INIS)
Angus, I.G.
1986-01-01
We present the most general spherically symmetric solution to the field equations of the truncated five-dimensional Kaluza-Klein theory. We also detail some of the special forms of this solution. With the exception of the Gross-Perry-Sorkin monopole and the Schwarzschild solutions we find that most, and we conjecture all, of the solutions have naked curvature singularities. We then proceed to consider higher-dimensional theories with toroidal compactification and we exhibit a class of nonsingular monopole solutions which are the natural generalization of the Gross-Perry-Sorkin monopole to more than five dimensions. We also present some selected solutions including a solution pertaining to a model with a Ricci-flat, but not curvature-flat, internal manifold. All of these other solutions have naked curvature singularities. (orig.)
Duality in Left-Right Symmetric Seesaw Mechanism
International Nuclear Information System (INIS)
Akhmedov, E.Kh.; Frigerio, M.
2006-01-01
We consider type I+II seesaw mechanism, where the exchanges of both right-handed neutrinos and isotriplet Higgs bosons contribute to the neutrino mass. Working in the left-right symmetric framework and assuming the mass matrix of light neutrinos m ν and the Dirac-type Yukawa couplings to be known, we find the triplet Yukawa coupling matrix f, which carries the information about the masses and mixing of the right-handed neutrinos. We show that in this case there exists a duality: for any solution f, there is a dual solution f-circumflex=m ν /v L -f, where v L is the vacuum expectation value of the triplet Higgs boson. Thus, unlike in pure type I (II) seesaw, there is no unique allowed structure for the matrix f. For n lepton generations the number of solutions is 2 n . We develop an exact analytic method of solving the seesaw nonlinear matrix equation for f
Statistical properties of anti-symmetrized molecular dynamics
International Nuclear Information System (INIS)
Ohnishi, A.; Randrup, J.
1993-01-01
We study the statistical equilibrium properties of the recently developed anti-symmetrized molecular dynamics model for heavy-ion reactions. We consider A non-interacting fermions in one dimension, either bound in a common harmonic potential or moving freely within an interval, and perform a Metropolis sampling of the corresponding parameter space. Generally the average excitation and the specific heat, considered as functions of the imposed temperature, behave in a classical manner when the canonical weight is calculated in the mean-field approximation. However, it is possible to obtain results that are much closer to the quantal behavior by modifying the weight to take approximate account of the energy fluctuations within the individual wave packets. (orig.)
Spontaneous symmetry breaking in the $S_3$-symmetric scalar sector
Emmanuel-Costa, D.; Osland, P.; Rebelo, M.N.
2016-02-23
We present a detailed study of the vacua of the $S_3$-symmetric three-Higgs-doublet potential, specifying the region of parameters where these minimisation solutions occur. We work with a CP conserving scalar potential and analyse the possible real and complex vacua with emphasis on the cases in which the CP symmetry can be spontaneously broken. Results are presented both in the reducible-representation framework of Derman, and in the irreducible-representation framework. Mappings between these are given. Some of these implementations can in principle accommodate dark matter and for that purpose it is important to identify the residual symmetries of the potential after spontaneous symmetry breakdown. We are also concerned with constraints from vacuum stability.
Darboux transformations and the symmetric fourth Painleve equation
International Nuclear Information System (INIS)
Sen, A; Hone, A N W; Clarkson, P A
2005-01-01
This paper is concerned with the group symmetries of the fourth Painleve equation P IV , a second-order nonlinear ordinary differential equation. It is well known that the parameter space of P IV admits the action of the extended affine Weyl group A-tilde 2 (1) . As shown by Noumi and Yamada, the action of A-tilde 2 (1) as Baecklund transformations of P IV provides a derivation of its symmetric form SP 4 . The dynamical system SP 4 is also equivalent to the isomonodromic deformation of an associated three-by-three matrix linear system (Lax pair). The action of the generators of A-tilde 2 (1) on this Lax pair is derived using the Darboux transformation for an associated third-order operator
Critical properties of symmetric nanoscale metal-ferroelectric-metal capacitors
International Nuclear Information System (INIS)
Zheng Yue; Cai, M.Q.; Woo, C.H.
2010-01-01
The size, surface and interface effects on the magnitude and stability of spontaneous polarization in a symmetric nanoscale ferroelectric capacitor were studied by analyzing its evolutionary trajectory based on a thermodynamic model. Analytic expressions of the Curie temperature, spontaneous polarization, critical thickness and the Curie-Weiss relation were derived, taking into account the effects of the depolarization field, built-in electric field, interfaces and surfaces. Our results show that the critical properties are not only functions of the ambient temperature, misfit strain and electromechanical boundary conditions, but also depend on the characteristics of electrodes, surfaces and interfaces, through the incomplete charge compensation, near-surface variation of polarization and work function steps of ferroelectric-electrode interfaces, which are adjustable.
Current simulation of symmetric contacts on CdTe
International Nuclear Information System (INIS)
Ruzin, A.
2011-01-01
This article presents the calculated current-voltage characteristics of symmetric Metal-Semiconductor-Metal configurations for Schottky, Ohmic, and injecting-Ohmic contacts on high resistivity CdTe. The results clearly demonstrate that in the wide band-gap, semi-insulating semiconductors, such as high resistivity CdTe, the linearity of the I-V curves cannot be considered a proof of the ohmicity of the contacts. It is shown that the linear I-V curves are expected for a wide range of contact barriers. Furthermore, the slope of these linear curves is governed by the barrier height, rather than the bulk doping concentration. Therefore the deduction of bulk's resistivity from the I-V curves may be false.
Current simulation of symmetric contacts on CdTe
Energy Technology Data Exchange (ETDEWEB)
Ruzin, A., E-mail: aruzin@post.tau.ac.il [School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, 69978 Tel Aviv (Israel)
2011-12-01
This article presents the calculated current-voltage characteristics of symmetric Metal-Semiconductor-Metal configurations for Schottky, Ohmic, and injecting-Ohmic contacts on high resistivity CdTe. The results clearly demonstrate that in the wide band-gap, semi-insulating semiconductors, such as high resistivity CdTe, the linearity of the I-V curves cannot be considered a proof of the ohmicity of the contacts. It is shown that the linear I-V curves are expected for a wide range of contact barriers. Furthermore, the slope of these linear curves is governed by the barrier height, rather than the bulk doping concentration. Therefore the deduction of bulk's resistivity from the I-V curves may be false.
Design of a polynomial ring based symmetric homomorphic encryption scheme
Directory of Open Access Journals (Sweden)
Smaranika Dasgupta
2016-09-01
Full Text Available Security of data, especially in clouds, has become immensely essential for present-day applications. Fully homomorphic encryption (FHE is a great way to secure data which is used and manipulated by untrusted applications or systems. In this paper, we propose a symmetric FHE scheme based on polynomial over ring of integers. This scheme is somewhat homomorphic due to accumulation of noise after few operations, which is made fully homomorphic using a refresh procedure. After certain amount of homomorphic computations, large ciphertexts are refreshed for proper decryption. The hardness of the scheme is based on the difficulty of factorizing large integers. Also, it requires polynomial addition which is computationally cost effective. Experimental results are shown to support our claim.
Static spherically symmetric wormholes in f(R, T) gravity
Energy Technology Data Exchange (ETDEWEB)
Zubair, M.; Ahmad, Yasir [Institute Of Information Technology, Department of Mathematics, COMSATS, Lahore (Pakistan); Waheed, Saira [Prince Mohammad Bin Fahd University, Al Khobar (Saudi Arabia)
2016-08-15
In this work, we explore wormhole solutions in f(R, T) theory of gravity, where R is the scalar curvature and T is the trace of stress-energy tensor of matter. To investigate this, we consider a static spherically symmetric geometry with matter contents as anisotropic, isotropic, and barotropic fluids in three separate cases. By taking into account the Starobinsky f(R) model, we analyze the behavior of energy conditions for these different kinds of fluids. It is shown that the wormhole solutions can be constructed without exotic matter in few regions of space-time. We also give the graphical illustration of the results obtained and discuss the equilibrium picture for the anisotropic case only. It is concluded that the wormhole solutions with anisotropic matter are realistic and stable in this theory of gravity. (orig.)
Capacity Bounds and Mapping Design for Binary Symmetric Relay Channels
Directory of Open Access Journals (Sweden)
Majid Nasiri Khormuji
2012-12-01
Full Text Available Capacity bounds for a three-node binary symmetric relay channel with orthogonal components at the destination are studied. The cut-set upper bound and the rates achievable using decode-and-forward (DF, partial DF and compress-and-forward (CF relaying are first evaluated. Then relaying strategies with finite memory-length are considered. An efficient algorithm for optimizing the relay functions is presented. The Boolean Fourier transform is then employed to unveil the structure of the optimized mappings. Interestingly, the optimized relay functions exhibit a simple structure. Numerical results illustrate that the rates achieved using the optimized low-dimensional functions are either comparable to those achieved by CF or superior to those achieved by DF relaying. In particular, the optimized low-dimensional relaying scheme can improve on DF relaying when the quality of the source-relay link is worse than or comparable to that of other links.
Control of Wind Turbines during Symmetrical and Asymmetrical Grid Faults
DEFF Research Database (Denmark)
Göksu, Ömer
As installed capacity of the wind power plants (WPPs) in power system of certain countries increases, stability of the power system becomes more critical. In order to sustain stable power system operation with high share of wind power, system operators of some countries are enforcing more stringent...... grid code requirements, which are targeting to make the WPPs operate in a closer manner to the conventional power plants. Common to most of the grid codes, WPPs are required to stay connected during short-circuit grid faults, and also inject reactive current in order to support the grid voltage...... type wind turbines (WTs), in an AC connected WPP, is investigated and control algorithms are designed for minimum disrupted operation and improved grid support, for both symmetrical and asymmetrical grid faults. WTs’ response with conventional control algorithms is studied regarding the impact...
Waterbomb base: a symmetric single-vertex bistable origami mechanism
International Nuclear Information System (INIS)
Hanna, Brandon H; Lund, Jason M; Magleby, Spencer P; Howell, Larry L; Lang, Robert J
2014-01-01
The origami waterbomb base is a single-vertex bistable origami mechanism that has unique properties which may prove useful in a variety of applications. It also shows promise as a test bed for smart materials and actuation because of its straightforward geometry and multiple phases of motion, ranging from simple to more complex. This study develops a quantitative understanding of the symmetric waterbomb base's kinetic behavior. This is done by completing kinematic and potential energy analyses to understand and predict bistable behavior. A physical prototype is constructed and tested to validate the results of the analyses. Finite element and virtual work analyses based on the prototype are used to explore the locations of the stable equilibrium positions and the force–deflection response. The model results are verified through comparisons to measurements on a physical prototype. The resulting models describe waterbomb base behavior and provide an engineering tool for application development. (paper)
A Low Frequency FBG Accelerometer with Symmetrical Bended Spring Plates
Directory of Open Access Journals (Sweden)
Fufei Liu
2017-01-01
Full Text Available To meet the requirements for low-frequency vibration monitoring, a new type of FBG (fiber Bragg grating accelerometer with a bended spring plate is proposed. Two symmetrical bended spring plates are used as elastic elements, which drive the FBG to produce axial strains equal in magnitude but opposite in direction when exciting vibrations exist, leading to doubling the wavelength shift of the FBG. The mechanics model and a numerical method are presented in this paper, with which the influence of the structural parameters on the sensitivity and the eigenfrequency are discussed. The test results show that the sensitivity of the accelerometer is more than 1000 pm/g when the frequency is within the 0.7–20 Hz range.
Symmetric-bounce quantum state of the universe
Energy Technology Data Exchange (ETDEWEB)
Page, Don N., E-mail: don@phys.ualberta.ca [Theoretical Physics Institute, Department of Physics, University of Alberta, Room 238 CEB, 11322 – 89 Avenue, Edmonton, Alberta T6G 2G7 (Canada)
2009-09-01
A proposal is made for the quantum state of the universe that has an initial state that is macroscopically time symmetric about a homogeneous, isotropic bounce of extremal volume and that at that bounce is microscopically in the ground state for inhomogeneous and/or anisotropic perturbation modes. The coarse-grained entropy is minimum at the bounce and then grows during inflation as the modes become excited away from the bounce and interact (assuming the presence of an inflaton, and in the part of the quantum state in which the inflaton is initially large enough to drive inflation). The part of this pure quantum state that dominates for observations is well approximated by quantum processes occurring within a Lorentzian expanding macroscopic universe. Because this part of the quantum state has no negative Euclidean action, one can avoid the early-time Boltzmann brains and Boltzmann solar systems that appear to dominate observations in the Hartle-Hawking no-boundary wavefunction.
Symmetric-bounce quantum state of the universe
International Nuclear Information System (INIS)
Page, Don N.
2009-01-01
A proposal is made for the quantum state of the universe that has an initial state that is macroscopically time symmetric about a homogeneous, isotropic bounce of extremal volume and that at that bounce is microscopically in the ground state for inhomogeneous and/or anisotropic perturbation modes. The coarse-grained entropy is minimum at the bounce and then grows during inflation as the modes become excited away from the bounce and interact (assuming the presence of an inflaton, and in the part of the quantum state in which the inflaton is initially large enough to drive inflation). The part of this pure quantum state that dominates for observations is well approximated by quantum processes occurring within a Lorentzian expanding macroscopic universe. Because this part of the quantum state has no negative Euclidean action, one can avoid the early-time Boltzmann brains and Boltzmann solar systems that appear to dominate observations in the Hartle-Hawking no-boundary wavefunction
Symmetric coupling of angular momenta, quadratic algebras and discrete polynomials
International Nuclear Information System (INIS)
Aquilanti, V; Marinelli, D; Marzuoli, A
2014-01-01
Eigenvalues and eigenfunctions of the volume operator, associated with the symmetric coupling of three SU(2) angular momentum operators, can be analyzed on the basis of a discrete Schrödinger–like equation which provides a semiclassical Hamiltonian picture of the evolution of a 'quantum of space', as shown by the authors in [1]. Emphasis is given here to the formalization in terms of a quadratic symmetry algebra and its automorphism group. This view is related to the Askey scheme, the hierarchical structure which includes all hypergeometric polynomials of one (discrete or continuous) variable. Key tool for this comparative analysis is the duality operation defined on the generators of the quadratic algebra and suitably extended to the various families of overlap functions (generalized recoupling coefficients). These families, recognized as lying at the top level of the Askey scheme, are classified and a few limiting cases are addressed
Timelike geodesics around a charged spherically symmetric dilaton black hole
Directory of Open Access Journals (Sweden)
Blaga C.
2015-01-01
Full Text Available In this paper we study the timelike geodesics around a spherically symmetric charged dilaton black hole. The trajectories around the black hole are classified using the effective potential of a free test particle. This qualitative approach enables us to determine the type of orbit described by test particle without solving the equations of motion, if the parameters of the black hole and the particle are known. The connections between these parameters and the type of orbit described by the particle are obtained. To visualize the orbits we solve numerically the equation of motion for different values of parameters envolved in our analysis. The effective potential of a free test particle looks different for a non-extremal and an extremal black hole, therefore we have examined separately these two types of black holes.
Globally optimal superconducting magnets part II: symmetric MSE coil arrangement.
Tieng, Quang M; Vegh, Viktor; Brereton, Ian M
2009-01-01
A globally optimal superconducting magnet coil design procedure based on the Minimum Stored Energy (MSE) current density map is outlined. The method has the ability to arrange coils in a manner that generates a strong and homogeneous axial magnetic field over a predefined region, and ensures the stray field external to the assembly and peak magnetic field at the wires are in acceptable ranges. The outlined strategy of allocating coils within a given domain suggests that coils should be placed around the perimeter of the domain with adjacent coils possessing alternating winding directions for optimum performance. The underlying current density maps from which the coils themselves are derived are unique, and optimized to possess minimal stored energy. Therefore, the method produces magnet designs with the lowest possible overall stored energy. Optimal coil layouts are provided for unshielded and shielded short bore symmetric superconducting magnets.
Ultrasound beam characteristics of a symmetric nodal origami based array
Bilgunde, Prathamesh N.; Bond, Leonard J.
2018-04-01
Origami-the ancient art of paper folding-is being explored in acoustics for effective focusing of sound. In this short communication, we present a numerical investigation of beam characteristics for an origami based ultrasound array. A spatial re-configuration of array elements is performed based upon the symmetric nodal origami. The effect of fold angle on the ultrasound beam is evaluated using frequency domain and transient finite element analysis. It was found that increase in the fold angle reduces near field length by 58% and also doubles the beam intensity as compared to the linear array. Transient analysis also indicated 80% reduction in the -6dB beam width, which can improve the lateral resolution of phased array. Such a spatially re-configurable array could potentially be used in the future to reduce the cost of electronics in the phased array instrumentation.
Hardware Realization of Chaos-based Symmetric Video Encryption
Ibrahim, Mohamad A.
2013-05-01
This thesis reports original work on hardware realization of symmetric video encryption using chaos-based continuous systems as pseudo-random number generators. The thesis also presents some of the serious degradations caused by digitally implementing chaotic systems. Subsequently, some techniques to eliminate such defects, including the ultimately adopted scheme are listed and explained in detail. Moreover, the thesis describes original work on the design of an encryption system to encrypt MPEG-2 video streams. Information about the MPEG-2 standard that fits this design context is presented. Then, the security of the proposed system is exhaustively analyzed and the performance is compared with other reported systems, showing superiority in performance and security. The thesis focuses more on the hardware and the circuit aspect of the system’s design. The system is realized on Xilinx Vetrix-4 FPGA with hardware parameters and throughput performance surpassing conventional encryption systems.
Optimum detection for extracting maximum information from symmetric qubit sets
International Nuclear Information System (INIS)
Mizuno, Jun; Fujiwara, Mikio; Sasaki, Masahide; Akiba, Makoto; Kawanishi, Tetsuya; Barnett, Stephen M.
2002-01-01
We demonstrate a class of optimum detection strategies for extracting the maximum information from sets of equiprobable real symmetric qubit states of a single photon. These optimum strategies have been predicted by Sasaki et al. [Phys. Rev. A 59, 3325 (1999)]. The peculiar aspect is that the detections with at least three outputs suffice for optimum extraction of information regardless of the number of signal elements. The cases of ternary (or trine), quinary, and septenary polarization signals are studied where a standard von Neumann detection (a projection onto a binary orthogonal basis) fails to access the maximum information. Our experiments demonstrate that it is possible with present technologies to attain about 96% of the theoretical limit
Information entropy for static spherically symmetric black holes
International Nuclear Information System (INIS)
Ji-Jian, Jiang; Chuan-An, Li
2009-01-01
By using the new equation of state density derived from the generalized uncertainty relation, the number of the quantum states near event horizon is obtained, with which then the information entropy of static spherically symmetric black holes has been discussed. It is found that the divergent integral of quantum states near the event horizon can be naturally avoided if using the new equation of state density without introducing the ultraviolet cut-off. The information entropy of black holes can be obtained precisely by the residue theorem, which is shown to be proportional to the horizon area. The information entropy of black holes obtained agrees with the Bechenstein–Hawking entropy when the suitable cutoff factor is adopted. (general)
Symmetric and Asymmetric Tendencies in Stable Complex Systems.
Tan, James P L
2016-08-22
A commonly used approach to study stability in a complex system is by analyzing the Jacobian matrix at an equilibrium point of a dynamical system. The equilibrium point is stable if all eigenvalues have negative real parts. Here, by obtaining eigenvalue bounds of the Jacobian, we show that stable complex systems will favor mutualistic and competitive relationships that are asymmetrical (non-reciprocative) and trophic relationships that are symmetrical (reciprocative). Additionally, we define a measure called the interdependence diversity that quantifies how distributed the dependencies are between the dynamical variables in the system. We find that increasing interdependence diversity has a destabilizing effect on the equilibrium point, and the effect is greater for trophic relationships than for mutualistic and competitive relationships. These predictions are consistent with empirical observations in ecology. More importantly, our findings suggest stabilization algorithms that can apply very generally to a variety of complex systems.
Generalized transformations and coordinates for static spherically symmetric general relativity
Hill, James M.; O'Leary, Joseph
2018-04-01
We examine a static, spherically symmetric solution of the empty space field equations of general relativity with a non-orthogonal line element which gives rise to an opportunity that does not occur in the standard derivations of the Schwarzschild solution. In these derivations, convenient coordinate transformations and dynamical assumptions inevitably lead to the Schwarzschild solution. By relaxing these conditions, a new solution possibility arises and the resulting formalism embraces the Schwarzschild solution as a special case. The new solution avoids the coordinate singularity associated with the Schwarzschild solution and is achieved by obtaining a more suitable coordinate chart. The solution embodies two arbitrary constants, one of which can be identified as the Newtonian gravitational potential using the weak field limit. The additional arbitrary constant gives rise to a situation that allows for generalizations of the Eddington-Finkelstein transformation and the Kruskal-Szekeres coordinates.