bluuebunny/crossref_metadata_2025 huggingface dataset:
Homeobox gene repertoire in adult rat dorsal root ganglia
Authors: Vogelaar Christina F. , Smits Simone M. , Brakkee Jan H. , Gispen Willem H. , Smidt Marten P. , Schrama Louise H. , Hoekman Marco F. M. , Burbach J. Peter H.
Published: March 2003

Homeobox genes encode transcription factors that play key roles in embryonic development of the nervous system. Dorsal root ganglia are part of the peripheral nervous system that arises from the neural crest. Several homeobox genes are known to play important roles in the development of neural crest and dorsal root ganglia. Some of these remain expressed in the adult dorsal root ganglia (DRG). In order to get more insight into the homeobox gene repertoire in adult rat DRG, we performed RT‐PCR with degenerate primers and identified twenty‐two homeobox genes. We found homeobox genes that were reported before in embryonic or adult DRG, as well as homeobox genes associated before with neural crest (derivatives). Some of the genes were not reported in relation to neural crest or DRG before. Two homeobox genes displayed sequence differences with their mouse counterparts, possibly being close homologues. The diversity of homeobox genes expressed in adult DRG suggests that gene regulatory events initiated during development remain operative in the mature DRG.
An improved numerical simulator for different types of flows in porous media
Authors: Wang Hong , Liang Dong , Ewing Richard E. , Lyons Stephen L. , Qin Guan
Published: March 2003

We develop an improved numerical simulator for subsurface compressible flows through porous media with point sources and sinks, which are governed by different equations of state. Computational experiments show that the simulator can generate stable simulation for different types of incompressible or compressible flows involving light or heavy components in porous media with point sources and sinks, large mobility ratios, discontinuous permeabilities and porosities, and anisotropic dispersion in tensor form, even though very large time steps and spatial grids are used. © 2003 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 19: 343–362, 2003.
Time discretizations for Maxwell‐Bloch equations
Authors: Bidégaray B.
Published: March 2003

In this article we derive new time discretizations for the numerical simulation of Maxwell‐Bloch equations. These discretizations decouple the equations, thus leading to improved efficiency. This approach may be combined with the fulfilment of physical properties, such as positiveness properties, which are not accounted for by classical schemes. Our time discretizations are moreover proved to be nonlinearly stable. © 2003 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 19: 284–300, 2003.
Numerical methods and error analysis for one dimensional elliptic problems containing singularities
Authors: Kim Hoonjoo , Lee Sung‐Jin , Oh Hae‐Soo
Published: March 2003

The method of auxiliary mapping (MAM), introduced by Babuška and Oh, was proven to be very successful in dealing with monotone singularities arising in two‐dimensional problems. In this article, in the framework of the p‐version of FEM, MAM is presented for one‐dimensional elliptic boundary value problems containing singularities. Moreover, in order to show the effectiveness of MAM, a detailed proof of an error estimate is also presented, which gives a sharp error bound of MAM. © 2003 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 19: 399–420, 2003.
Has welfare reform changed teenage behaviors?
Authors: Kaestner Robert , Korenman Sanders , O'Neill June
Published: March 2003

Data from the National Longitudinal Surveys of Youth 1979 and 1997 cohorts were used to compare welfare use,
fertility, educational attainment, and marriage among teenage women in the years before and immediately
following welfare reform. The first objective was to document differences between these cohorts in welfare use
and outcomes and behavior correlated with entry into welfare and with future economic and social
well‐being. The second objective was to investigate the causal role of welfare reform in behavioral
change. Significant differences were found between cohorts in welfare use and in outcomes related to welfare
use. Furthermore, difference‐in‐differences estimates suggest that welfare reform has been
associated with reduced welfare receipt, reduced fertility, and reduced marriage among young women who, because
of a disadvantaged family background, are at high risk of welfare receipt. Finally, in the post‐welfare
reform era, teenage mothers are less likely to receive welfare and are more likely to live with at least one
parent than in the pre‐reform era. Establishing more definitively that welfare reform is responsible for
these changes will require further investigation. © 2003 by the Association for Public Policy Analysis and
Management.
Role for macrophage migration inhibitory factor in acute respiratory distress syndrome
Authors: Lai Kar Neng , Leung Joseph CK , Metz Christine N , Lai Fernand M , Bucala Richard , Lan Hui Yao
Published: March 2003

The critical role of macrophage migration inhibitory factor (MIF) in mediating inflammatory lung injury in acute respiratory distress syndrome (ARDS) has been raised recently. The present study has identified enhanced MIF protein expression in alveolar capillary endothelium and infiltrating macrophages in lung tissues from ARDS patients. The possibility that MIF up‐regulates its synthesis in an autocrine fashion in ARDS was tested using cultured endothelial cells stimulated with MIF and a murine model of lipopolysaccharide (LPS)‐induced acute lung injury. MIF induced significant MIF and tumour necrosis factor (TNF)‐α synthesis in cultured endothelial cells and the effect was blocked by neutralizing anti‐MIF antibody. A similar blocking effect was observed when MIF‐stimulated endothelial cells were pretreated with neutralizing anti‐TNF‐α antibody or glucocorticoid, supporting the notion that MIF induced TNF‐α production via an amplifying pro‐inflammatory loop. Treatment with anti‐MIF or glucocorticoid effectively attenuated pulmonary pathology and the synthesis of MIF or TNF‐α in mice with LPS‐induced acute lung injury. Mildly augmented expression of aquaporin 1 (AQP1) was also detected in alveolar capillary endothelium in ARDS. In vitro studies revealed that both MIF and TNF‐α induced a small increase of AQP1 synthesis in cultured endothelial cells. These findings suggest that MIF plays a crucial pathological role leading to alveolar inflammation in ARDS. Anti‐MIF and early glucocorticoid therapy may represent a novel therapeutic approach for reducing alveolar inflammation in ARDS. Copyright © 2003 John Wiley & Sons, Ltd.
Therapieempfehlungen in der Apotheke: Topische Antimykotika
Authors: Kresken Joachim
Published: March 2003

Mit der Entlassung zahlreicher topischer Antimykotika aus der Verschreibungspflicht und den damit verbundenen erweiterten Möglichkeiten zur Selbstmedikation hat die Apotheke bei der Behandlung von Dermatomykosen an Bedeutung und Verantwortung gewonnen. Da sie häufig die erste Anlaufstelle der Betroffenen ist, beeinflussen die dort ausgesprochenen Therapieempfehlungen den weiteren Krankheitsverlauf. Außerdem kann die Apotheke mit ihrer Beratung einen wichtigen Beitrag zur Förderung der insbesondere bei den Azolderivaten suboptimalen Patientencompliance leisten. Um diesen Aufgaben nachkommen zu können, sind Kenntnisse über die Symptome, mögliche Folgeerkrankungen, Differentialdiagnosen und Behandlungsmaßnahmen der zahlenmäßig bedeutsamsten Dermatomykosen notwendig, die durch geeignete Fortbildungsmaßnahmen erworben werden müssen.
Neues zum alten Histamin I. Ein weiteres Mitglied in der Rezeptorfamilie
Authors: Stark Holger , Schlegel Birgit , Sippl Wolfgang
Published: March 2003

Die Entdeckung eines neuen Histamin‐H4‐Subrezeptors beim Menschen könnte zu neuen Kenntnissen über immunologische Prozesse führen.
Comparison of models of maternal age‐specific risk for Down syndrome live births
Authors: Morris J. K. , Wald N. J. , Mutton D. E. , Alberman E.
Published: March 2003

Objectives

To display and compare the different published formulae that specify the association between maternal age and the risk of a Down syndrome live birth.

Methods

Papers published since 1987 on the prevalence of Down syndrome live births in relation to maternal age were located using MEDLINE and the references given in other papers. The data series and the models fitted to them were plotted to obtain a visual idea of their similarities and differences.

Results

The observed and modelled age‐specific rates for Down syndrome births were remarkably similar in all published series of data for women up to the age of 35, were reasonably similar for women aged 35 to 45, but differed for women older than 45.

Conclusion

In practice, the overall small differences in age‐related risk between the different studies did not materially affect the performance of antenatal screening for Down syndrome. If a choice is to be made, the analysis based on the National Down Syndrome Cytogenetic Register (NDSCR) has marginal advantages since it is based on the largest data set and the corresponding model fits the data well. More data is needed to clarify the pattern of risk with maternal age among women over 45 years of age. Copyright © 2003 John Wiley & Sons, Ltd.
First‐trimester nuchal translucency measurement and echocardiography at 16 to 18 weeks of gestation in prenatal detection for trisomy 18
Authors: Cheng Po‐Jen , Liu Ching‐Ming , Chueh Ho‐Yen , Lin Chien‐Ming , Soong Yung‐Kwei
Published: March 2003

Background

Trisomy 18, the second most common autosomal trisomy, has the highest incidence of congenital heart disease of all chromosomal abnormalities. This study assessed the use of nuchal translucency (NT) measurement and fetal echocardiography at 16 to 18 weeks of gestation in prenatal detection for trisomy 18.

Methods

Screening for chromosomal aneuploidy using fetal NT measurement was performed at 10 to 14 weeks of gestation. Detailed fetal echocardiography was performed at 16 to 18 weeks of gestation immediately before genetic amniocentesis for fetal karyotyping in singleton pregnancies with increased fetal NT thickness.

Results

Of the 3151 singleton pregnancies included in our study, 171 cases (5.4%) of increased (≥3.0 mm) NT were noted. Fetal chromosomal abnormalities were identified in 22 (12.9%) of these pregnancies, including 9 with trisomy 21, 5 with trisomy 18, 4 with 45,X and 4 with unbalanced structural abnormalities. Major defects of the heart and the great arteries were identified in 13 (7.6%) of these pregnancies with increased NT. These included eight pregnancies that also had the diagnosis of chromosomal aneuploidy. Among the 22 fetuses with confirmed aneuploidy, all 5 fetuses with trisomy 18, 1 of the 4 fetuses with 45,X and 2 of the 9 fetuses with trisomy 21 had increased fetal NT thickness associated with abnormal fetal echocardiography findings.

Conclusions

Screening for Down syndrome and cardiac defects using first‐trimester fetal NT measurement in combination with fetal echocardiography at 16 to 18 weeks of gestation is a feasible and sensitive procedure for the prenatal detection of trisomy 18. Copyright © 2003 John Wiley & Sons, Ltd.
Bulk passivation of multicrystalline silicon solar cells induced by high‐rate‐deposited (> 1 nm/s) silicon nitride films
Authors: Hong J. , Kessels W. M. M. , van Assche F. J. H. , Rieffe H. C. , Soppe W. J. , Weeber A. W. , van de Sanden M. C. M.
Published: March 2003

Silicon nitride (a‐SiNx:H) films deposited by the expanding thermal plasma at high rate (> 1 nm/s) have been studied for application as anti‐reflection coatings for multicrystalline silicon (mc‐Si) solar cells. Internal quantum efficiency measurements have revealed that bulk passivation is achieved after a firing‐through process of the a‐SiNx:H as deposited from NH3/SiH4 and N2/SiH4 plasmas. However, the a‐SiNx:H films deposited from N2/SiH4 show a lower passivation quality than those deposited from NH3/SiH4. This has been attributed to a poorer thermal stability of the films deposited from the N2/SiH4 plasma, resulting in structural changes within the film during the firing step. Copyright © 2002 John Wiley & Sons, Ltd.
Das Sterninterferometer auf dem Paranal: Teleskoptechnik
Authors: Glindemann Andreas
Published: March 2003

Mit der Interferometrie kann das Winkelauflösungsvermögen gegenüber der Beobachtung mit einem Einzelteleskop enorm gesteigert werden. Im Jahr 2001 wurden zum ersten Mal die 8‐m‐Teleskope der ESO auf dem Cerro Paranal zu einem Sterninterferometer kombiniert. In den nächsten Jahren wird sich herausstellen, ob Sterninterferometer die Astronomie genau so prägen werden, wie es Radiointerferometern in den letzten Jahrzehnten gelungen ist.
Das Spiel mit der kritischen Masse
Authors: Loos Andreas
Published: March 2003

Er wird in ein wohlhabendes Elternhaus geboren. Als Jugendlicher besitzt er eine Segeljacht, als Student trägt er Anzüge, die sich keiner seiner Kommilitonen leisten kann, und als junger Professor verdient er mit privaten Einkünften doppelt so viel wie mit dem Professorengehalt.
Evaluation of nonionic and zwitterionic detergents as membrane protein solubilizers in two‐dimensional electrophoresis
Authors: Luche Sylvie , Santoni Véronique , Rabilloud Thierry
Published: March 2003

The solubilizing power of various nonionic and zwitterionic detergents as membrane protein solubilizers for two‐dimensional electrophoresis was investigated. Human red blood cell ghosts and Arabidopsis thaliana leaf membrane proteins were used as model systems. Efficient detergents could be found in each class, i.e. with oligooxyethylene, sugar or sulfobetaine polar heads. Among the commercially available nonionic detergents, dodecyl maltoside and decaethylene glycol mono hexadecyl ether proved most efficient. They complement the more classical sulfobetaine detergents to widen the scope of useful detergents for the solubilization of membrane proteins in proteomics.
Degradation of a poly(ester urethane) elastomer. III. Estane 5703 hydrolysis: Experiments and modeling
Authors: Salazar Michael R. , Lightfoot J. Michael , Russell Bobby G. , Rodin Wayne A. , McCarty Melanie , Wrobleski Debra A. , Orler E. Bruce , Spieker David A. , Assink Roger A. , Pack Russell T
Published: March 2003

Hydrolytic degradation data from a wide variety of experiments on Estane 5703, a commercial poly(ester urethane), are modeled with an AAC2 mechanism of reversible esterification and hydrolysis together with a cluster model for water concentration. The experimental conditions spanned a range of temperatures from 21 to 95 °C, relative humidities from 0 to 100%, times up to more than 30 years, and different initial molecular weights and acidities. In addition, the experiments were performed in several different laboratories with a number of different instruments and techniques. All the experimental data, both for molecular weight and acidity, are modeled with a single set of concentration‐independent rate coefficients, and the kinetic model fits the data well and constitutes a robust model of the hydrolytic degradation of this polymer. The results also show that ester hydrolysis is the dominant cause of the molecular weight loss of Estane 5703 in indoor storage at ambient temperatures and humidities. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1136–1151, 2003
Modification of the universal calibration of gel permeation chromatography to include macromolecules presenting a draining effect
Authors: Dondos Anastasios , Papanagopoulos Dimitrios
Published: March 2003

A new universal calibration for gel permeation chromatography is proposed in which the hydrodynamic volume of the macromolecular chains is expressed by the quantity [η]M/Φ instead of the commonly used quantity [η]M (where [η] is the intrinsic viscosity, M is the molecular mass, and Φ is Flory's parameter). Introducing Φ into the hydrodynamic volume is necessary because its value changes from one polymer to another when the polymers present a certain draining effect. The proposed procedure also allows the determination of Φ of any wormlike polymer. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 707–710, 2003
Comparisons of distress in adolescents of cancer patients and controls
Authors: Harris Casey A. , Zakowski Sandra G.
Published: March 2003

Having a family member with cancer has been associated with symptoms of distress. While studies have reported distress in adolescents with a parent with cancer, few have included control groups of adolescents with healthy parents. Adolescents who had at least one parent diagnosed with cancer (n=27) and controls (n=23) completed questionnaires on PTSD, anxiety, depression, cancer risk perceptions, and family environment. Groups did not differ on anxiety and depression, but adolescents with an ill parent perceived their own risk for developing cancer as significantly higher than controls. Controls reported significantly higher levels of intrusive thoughts and avoidance regarding other stressful life events. A positive family environment was correlated with higher anxiety and depression, and expressiveness mediated the relations between family cohesion and anxiety. These preliminary findings suggest that distress reported in previous studies of adolescents with parents with cancer may be due to this transitional period of life. Copyright © 2002 John Wiley & Sons, Ltd.
Cancer knowledge among Spanish women participating in literacy schemes
Authors: Estapé Tania , Estapé Jordi , Grau Juan J. , Ferrer Conxita
Published: March 2003

Access to information on cancer prevention and treatment is often difficult for ethnic or low socio‐economic groups. This study aimed to ascertain level of knowledge about cancer, and breast cancer in particular, in Spanish women from low socio‐economic groups participating in literacy schemes. A study specific questionnaire was administered to 541 women All participants were married with a median of 2 children, and a total family income of less than 10,000 euros per year. The main themes covered: understanding of and access to screening, knowledge about cancer risk, diagnosis and prognosis.

The majority of these women (66%) feel they have no control over getting cancer and 26% report that it can be caught from others. Most believe that a mammogram is the best method of diagnosis (87%) but a minority (14%) agree with the statement that breast cancer can be caused by breast feeding. In general, younger women are better informed and more optimistic about prognosis.

In Spain there are problems in disseminating information about cancer to lower social‐economic groups. These results confirm that more cancer education needs to be directed to low income and socially deprived groups. Copyright © 2003 John Wiley & Sons, Ltd.
Risk factors for initial acquisition of Pseudomonas aeruginosa in children with cystic fibrosis identified by newborn screening
Authors: Maselli Judith H. , Sontag Marci K. , Norris Jill M. , MacKenzie Todd , Wagener Jeff S. , Accurso Frank J.
Published: March 2003

The objective of this study was to identify risk factors for initial detection of Pseudomonas aeruginosa (P. aeruginosa) in children with cystic fibrosis (CF) identified by newborn screening. Life history data on 180 patients, collected prospectively in a follow‐up study of infants and children diagnosed with CF, were examined for factors associated with the initial detection of P. aeruginosa ascertained by oropharyngeal cultures. Univariate and multivariate Cox proportional hazards regression analyses were used to assess the effect of baseline and time‐varying covariates on age at first positive culture for P. aeruginosa. Seventy‐nine patients (44%) had at least one culture positive for P. aeruginosa during the study. The median age of detection was 8.1 years (95% CI, 7.0, 10.0). Median length of follow‐up was 4.1 years, ranging from 0.2–15.5 years. Multivariate Cox regression analysis identified female gender (RR, 1.85; 95% CI, 1.14, 3.01), the ΔF508 homozygous genotype (RR, 2.23; 95% CI, 1.30, 3.80), and S. aureus isolations (RR, 1.30; 95% CI, 1.11, 1.52) to be independently associated with acquisition of P. aeruginosa. Other marginally independent associations were found with days hospitalized and increased height. We conclude that female gender, homozygous ΔF508 mutation, and S. aureus isolations are important risk factors for early P. aeruginosa detection in children with CF identified through newborn screening. Pediatr Pulmonol. 2003; 35:257–262. © 2003 Wiley‐Liss, Inc.
Anti‐inflammatory treatment for recurrent wheezing in the first five years of life
Authors: Kaditis Athanasios G. , Gourgoulianis Konstantinos , Winnie Glenna
Published: March 2003

Medications identified for the treatment of recurrent wheezing in preschool children by the Expert Panel Report of the NHLBI Guidelines for the Diagnosis and Management of Asthma include inhaled corticosteroids, chromones, theophylline, and leukotriene pathway modifiers. However, these various agents differ in their mechanism, extent of action on the airway inflammatory process, and degree of clinical efficacy. Inhaled corticosteroids can control symptoms in many young children with even severe persistent wheezing, but data on their long‐term safety when administered in preschool‐age children are scarce. There is some information on the uninterrupted use of inhaled corticosteroids in school‐age children and the absence of an adverse effect on ultimate adult height. Despite laboratory evidence of adrenal suppression in some studies, few pediatric cases of clinical adrenal insufficiency have been reported. Low‐dose inhaled corticosteroid (<400 mcg/day for beclomethasone), which is adequate for controlling mild persistent symptoms, is generally safe. Chromones have a remarkable safety profile, but they are most effective for symptoms of mild severity. Promising data have been published on the efficacy and safety of leukotriene pathway modifiers when used in young children with persistent symptoms. It is uncertain whether early introduction and long‐term administration of inhaled corticosteroids prevent development of irreversible airway obstruction. Nevertheless, they may be especially useful for patients with moderate to severe disease in whom other agents (chromones or leukotriene pathway modifiers) will most likely fail to control symptoms. Pediatr Pulmonol. 2003; 35:241–252. © 2003 Wiley‐Liss, Inc.
Pulmonary edema of enterovirus 71 encephalomyelitis is associated with left ventricular failure: Implications for treatment
Authors: Fu Yun‐Ching , Chi Ching‐Shiang , Jan Sheng‐Ling , Wang Teh‐Ming , Chen Po‐Yen , Chang Yen , Chou Guan , Lin Chieh‐Chung , Hwang Betau , Hsu Shih‐Lan
Published: March 2003

Epidemics of enterovirus 71 infections caused the rapid death of many children in Malaysia in 1997 and in Taiwan in 1998. Pulmonary edema occurred in most of the fatal cases and was considered to be neurogenic. The role of the heart was rarely investigated before. Between January 1998–January 2001, 34 consecutive patients who were admitted to the intensive care unit due to enterovirus infection were studied prospectively. Patients were divided into two groups: group I with pulmonary edema, and group II without pulmonary edema. Comparisons were made between the two groups based upon demographic, neurological, and cardiovascular manifestations. Group I consisted of 11 patients (5 boys, 6 girls; mean age, 22.8 months), and group II of 23 patients (12 boys, 11 girls; mean age, 28.8 months). There were no significant differences between the two groups in comparing sex, age, body weight, neurological severity, intracranial pressure, cell count, protein and glucose levels in cerebral spinal fluid, and blood pressure. All group I patients had left ventricular dysfunction, and their ejection fractions were significantly lower than those of patients in group II (37 ± 11% vs. 75 ± 6%, P < 0.001). Group I heart rates were higher than those of group II (175 ± 24 vs. 137 ± 25, P < 0.001). In group I, 9 patients who received conventional treatment died, and the only two survivors received left ventricular assist devices. In conclusion, the pulmonary edema of fulminant enterovirus 71 infection is associated with left ventricular failure. Left ventricular function is the major determinant of outcome. Early recognition of heart failure and aggressive cardiac intervention are life‐saving. Pediatr Pulmonol. 2003; 35:263–268. © 2003 Wiley‐Liss, Inc
Novel Segmented Thermoplastic Polyurethanes Elastomers Based on Tetrahydrofuran Ethylene Oxide Copolyethers as High Energetic Propellant Binders
Authors: Chen Fu‐Tai , Duo Ying‐Quan , Luo Shan‐Guo , Luo Yun‐Jun , Tan Hui‐Min
Published: March 2003

Novel thermoplastic polyurethane (TPU) elastomers based on copolyether (tetrahydrofuran ethylene oxide) as soft segments, isophorone diisocyanate and 1,4‐butanediol as hard segments were synthesized for the purpose of using as propellant binders. In order to increase the miscibility of thermoplastic polyurethane elastomers with nitrate ester, polyethylene glycol (PEG) is incorporated in the co‐polyether (tetrahydrofuran ethylene oxide) as soft segment. When the molecular weight and content of polyethylene glycol are controlled to 4000 and 6% of soft segments, respectively, the properties of thermoplastic polyurethane elastomers are most perfect. If plasticizing ratio of nitrate ester to thermoplastic polyurethane elastomers exceeds 4 no crystallinities are determined at room temperature. The propellant samples were prepared by a conventional absorption‐rolling extrusion process and the mechanical and combustion properties evaluated afterwards. The maximum impulse reaches up to 265∼270 s which is a little bit higher than that of a HTPB propellant. The measured results reveal a promising TPE propellant candidate which shows good processing temperature (<393 K) and excellent mechanical properties. An attracting feature which can be pointed out is that the burning rate pressure exponent reaches as low as 0.36 without the addition of burning rate catalysts. This enables an easy control of propellant combustion.
Programmable quantum measurement device that approximates all projective measurements on a qubit
Authors: Fiurášek J. , Dušek M. , Filip R.
Published: March 2003

A “universal” quantum measurement device is proposed. It can approximate any projective measurement on a qubit. The measurement basis is selected by the quantum state of a “program register''. The device is optimized with respect to maximal average fidelity. A contra‐intuitive result is that if two qubits in the same state are used as a program the average fidelity is higher than if the second program qubit is in the respective orthogonal state.
Hidden nonlocality in quantum complementarity
Authors: Filip R.
Published: March 2003

Bell's inequality violation in the which‐way experiment, demonstrating duality between visibility and distinguishability, is analyzed with taking to account the decoherence in the interferometer and which‐way detector. Consequently, boundary of local hidden variable explanation of quantum complementarity is discussed, and usefulness of the collective tests reveling hidden nonlocality is demonstrated.
Robustness of coherent control with light induced potentials
Authors: Garraway B.M. , Suominen K.‐A.
Published: March 2003

Intense pulses of light can be used to guide a molecular system into particular molecular states even when the Franck‐Condon overlap is very small. The process of APLIP (Adiabatic Passage by Light Induced Potentials) is an example where light induced potentials effect the change of electronic state whilst maintaining the vibrational state. In this paper we look at the robustness of APLIP to some of its controlling parameters.
Antisymmetric multi‐partite quantum states and their applications
Authors: Jex I. , Alber G. , Barnett S.M. , Delgado A.
Published: March 2003

Entanglement is a powerful resource for processing quantum information. In this context pure, maximally entangled states have received considerable attention. In the case of bipartite qubit‐systems the four orthonormal Bell‐states are of this type. One of these Bell states, the singlet Bell‐state, has the additional property of being antisymmetric with respect to particle exchange. In this contribution we discuss possible generalizations of this antisymmetric Bell‐state to cases with more than two particles and with single‐particle Hilbert spaces involving more than two dimensions. We review basic properties of these totally antisymmetric states. Among possible applications of this class of states we analyze a new quantum key sharing protocol and methods for comparing quantum states.
Quantum trajectory approach to stochastically‐induced quantum interference
Authors: Karpati A. , Adam P. , Gawlik W. , Lobodzinski B. , Janszky J.
Published: March 2003

Stochastic perturbation of two‐level atoms strongly driven by a coherent light field is analyzed by the quantum trajectory method. Narrow resonances as hole burning and dispersive Fano‐like profile occur in the spectra in the regime where the noise dominates the Rabi oscillations. It is shown that in this case the stochastic noise can unexpectedly create phase correlation between the neighboring atomic dressed states. This phase correlation is responsible for quantum interference between the related transitions resulting in anomalous modifications of the resonance fluorescence spectra.
Revealing non‐classical behaviours in the oscillatory motion of a trapped ion
Authors: Militello B. , Messina A. , Napoli A.
Published: March 2003

The possibility of revealing non‐classical behaviours in the dynamics of a trapped ion via measurements of the mean value of suitable operators is reported. In particular we focus on the manifestation known as “Parity Effect” which may be observed directly measuring the expectation value of an appropriate correlation operator. The experimental feasibility of our proposal is discussed.
Engineering QND measurements for continuous variable quantum information processing
Authors: Paris M.G.A.
Published: March 2003

A novel scheme to realize the whole class of quantum nondemolition (QND) measurements of a field quadrature is suggested. The setup requires linear optical components and squeezers, and allows optimal QND measurements of quadratures, which minimize the information gain versus state disturbance trade‐off.
Covariant phase observables
Authors: Pellonpää J.‐P.
Published: March 2003

Covariant phase observables constitute a simple solution of the quantum phase problem of a single‐mode optical field. They share three important properties: their range of values is the phase interval [0,2π), they are covariant under shifts generated by the number operator (which is necessary for coherent state phase measurements), and they have the uniform phase distribution in number states. Moreover, some phase observables have been measured (e.g. the phase observable associated to the Q‐function). The canonical phase observable has some additional properties which distinguish it from other covariant phase observables: it generates number shifts, it is uniquely associated to the polar decomposition of the lowering operator (Dirac's idea [1]), it has a projection valued covariant dilation (Newton's extension [2]), and it has a projection valued discretization (the Pegg‐Barnett formalism [3]). The single‐mode covariant phase theory can easily be extended to the two‐mode theory of covariant phase difference observables. Finally, most of all phase theories have connections to the covariant phase theory.
Cavity QED with a trapped ion
Authors: Vogel W. , Di Fidio C.
Published: March 2003

A trapped ion in a leaky cavity is studied in the regime of strong atom‐field coupling. Particular emphasis is paid on nonlinearities due to smooth localization of the ion's wavefunction and on decoherence effects caused by spontaneous emission and cavity losses. Possibilities of quantum‐state preparation are analyzed and single‐ion lasing is considered.
On the absence of large‐order divergences in superstring theory
Authors: Davis S.
Published: March 2003

The genus‐dependence of multi‐loop superstring amplitudes is estimated at large orders in perturbation theory using the super‐Schottky group parameterization of supermoduli space. Restriction of the integration region to a subset of supermoduli space and a single fundamental domain of the super‐modular group suggests an exponential dependence on the genus. Upper bounds for these estimates are obtained for arbitrary N‐point superstring scattering amplitudes and are shown to be consistent with exact results obtained for special type II string amplitudes for orbifold or Calabi‐Yau compactifications. The genus‐dependence is then obtained by considering the effect of the remaining contribution to the superstring amplitudes after the coefficients of the formally divergent parts of the integrals vanish as a result of a sum over spin structures. The introduction of supersymmetry therefore leads to the elimination of large‐order divergences in string perturbation theory, a result which is based only on the supersymmetric generalization of the Polyakov measure and not the gauge group of the string model.
Modelling of defects and surfaces in perovskite ferroelectrics
Authors: Borstel G. , Eglitis R. I. , Kotomin E. A. , Heifets E.
Published: March 2003

The results of electronic structure calculations for different terminations of SrTiO3 (100) and (110) perovskite thin films are discussed. These calculations are based on the ab initio Hartree‐Fock (HF) method and Density Functional Theory (DFT). Results are compared with previous ab initio plane‐wave LDA and classical Shell Model (SM) calculations. Calculated considerable increase of the Ti–O chemical bond covalency nearby the surface is confirmed by experimental data. Our quantum chemical calculations performed by means of the intermediate neglect of differential overlap (INDO) method confirm the existence of self‐trapped electrons in KNbO3, KTaO3 and BaTiO3 crystals. The relevant lattice relaxation energies are 0.21 eV, 0.27 eV and 0.24 eV, and the optical absorption energies 0.78 eV, 0.75 eV and 0.69 eV, respectively. We suggest a theoretical interpretation of the so‐called green luminescence (2.2–2.3 eV) in ABO3 perovskite crystals as a result of the recombination of electrons and holes forming the Charge‐Transfer‐Vibronic‐Exciton (CTVE). The calculated luminescence energies for SrTiO3, BaTiO3, KNbO3 and KTaO3 perovskite crystals are in a good agreement with the experimentally observed energies.
Orbital ordering and orbital fluctuations in transition metal oxides
Authors: Oleś Andrzej M.
Published: March 2003

We summarize some characteristic features of the frustrated magnetic interactions in spin‐orbital models adequate for cubic transition metal oxides with orbital degeneracy. A generic tendency towards dimerization, found already in the degenerate Hubbard model, is confirmed for t2g but not for eg systems. In the t2g case the quantum orbital fluctuations are more pronounced and contribute to a stronger competition between different magnetic and orbital states. Therefore the orbital liquid states exist in some undoped t2g systems, while in the manganites such states can be triggered only by doping.
Spinelectronics and its applications
Authors: Reiss G. , Brückl H. , Hütten A. , Schmalhorst J. , Justus M. , Thomas A. , Heitmann S.
Published: March 2003

The discovery of antiferromagnetic coupling in metallic Fe/Cr multilayers by Grünberg has triggered enormous research activities in the area of magnetic thin films. Additionally, the resistance of multilayers in the antiferromagnetic state is higher than in the parallel state at magnetic saturation. This Giant Magneto Resistance is caused by spin‐dependent scattering of the conduction electrons in the magnetic layers. For applications, however, moderate saturation fields, tailorable resistance characteristics and good temperature stability are required. Additional opportunities are opened by a similar effect in magnetic tunnel junctions. Here, the tunneling probability depends on the relative orientation of the magnetizations of the electrodes and thus a large dependence of the tunneling current on an external magnetic field can be found. This effect is usually called Tunneling Magneto Resistance and can again be used both for detecting external fields as well as for information storage. Much more possible applications are still ahead, especially after the finding of magnetoelectronic effects in semiconductors. In this contribution, we will sketch basic physics of these effects and give examples for current developments.
Nanocrystalline soft magnetic materials: intergrain coupling and spin freezing effects
Authors: Škorvánek I. , Kováč J. , Kötzler J.
Published: March 2003

The static and dynamic magnetic properties of the nanocrystalline soft magnetic FeNbB alloys consisting of Fe‐nanograins embedded in an amorphous matrix were investigated by means of dc and ac susceptibility, magnetization and hysteresis loop measurements in a wide temperature range. We show that these alloys exhibit particular complex magnetic behaviour versus temperature. The spin‐glass like behaviour at cryogenic temperatures is followed by a very soft magnetic behaviour at intermediate temperatures, and finally, a marked magnetic hardening due to decoupling between the nanograins is observed when temperature approaches the Curie temperature of the amorphous matrix. Upon further increase of temperature, the thermal relaxation of magnetization plays a dominant role. The results are discussed within a model that takes into account the presence of weakly magnetic Nb‐rich shells around the nanocrystalline grains.
Stripe fractionalization: the quantum spin nematic and the Abrikosov lattice
Authors: Zaanen J. , Nussinov Z.
Published: March 2003

In part (I) of this two paper series on stripe fractionalization [J. Phys. IV (France) 12, Prg‐245 (2002)], we argued that in principle the “domain wall‐ness” of the stripe phase could persist in the spin and charge disordered superconductors, and we demonstrated how this physics is in one‐to‐one correspondence with Ising gauge theory. Here we focus on yet another type of order suggested by the gauge theory: the quantum spin nematic. Although it is not easy to measure this order directly, we argue that the superconducting vortices act as perturbations destroying the gauge symmetry locally. This turns out to give rise to a simple example of a gauge‐theoretical phenomenon known as topological interaction. As a consequence, at any finite vortex density a globally ordered antiferromagnet emerges. This offers a potential explanation for recent observations in the underdoped 214 system.
Kondo effect in the presence of crystal‐field in Ce–Ni–Ge compounds
Authors: Pikul A. P. , Kaczorowski D. , Rogl P. , Grin Yu.
Published: March 2003

Polycrystalline samples of CeNiGe3, Ce2Ni3Ge5, Ce3NiGe2, Ce3Ni2Ge7, and their nonmagnetic La or Y‐based analogues were studied by means of electrical resistivity measurements. The temperature dependencies of the electrical resistivity of YNiGe3, La2Ni3Ge5, La3NiGe2, and La3Ni2Ge7 are typical for simple intermetallics. In turn, the magnetic contributions ρmag(T) to the resistivity of the Ce‐based phases reveal in the paramagnetic region logarithmic slopes and humps, characteristic of Kondo systems with strong crystal‐field interactions, as predicted by the Cornut–Coqblin theory. The total crystal‐field splittings of the 2F5/2 ground multiplet of Ce3+ ions were estimated to be of 100–200 K. In the magnetically ordered region the resistivity strongly decreases showing at the lowest temperatures a behavior typical for electron–magnon scattering.
Correlated hopping in infinite dimensions: rigorous local approach
Authors: Shvaika A. M.
Published: March 2003

A general approach for the description of correlated hopping in the dynamical mean‐field theory, which is based on the expansion over electron hopping around the atomic limit, is developed. It is formulated in terms of the local irreducible parts (cumulants) of Green's functions and allows to calculate thermodynamical functions. As a limiting case the Falicov–Kimball model with correlated hopping is considered.
Vertical and diagonal stripes in the extended Hubbard model
Authors: Raczkowski M. , Normand B. , Oleś A. M.
Published: March 2003

We extend previous real‐space Hartree–Fock studies of static stripe stability to determine the phase diagram of the Hubbard model with anisotropic nearest‐neighbor hopping t, by varying the on‐site Coulomb repulsion U and investigating locally stable structures for representative hole doping levels x = 1/8 and x = 1/6. We also report the changes in stability of these stripes in the extended Hubbard model due to next‐neighbor hopping t′ and to a nearest‐neighbor Coulomb interaction V.
Tunneling current in ferromagnetic metal – odd parity superconductor junction
Authors: Wojciechowski R. J. , Kowalewski L. , Wojtuś P.
Published: March 2003

The properties of tunneling conductance spectra of a ferromagnetic metal–insulator‐spin triplet superconductor junction are investigated. We take into account higher (p‐wave and f‐wave) relative angular momentum contributions to the superconducting order parameter and investigate the quasiparticle tunneling for both the unitary and non‐unitary pairing states, which are consistent with the experimental data for Sr2RuO4. The zero‐bias conductance peaks due to the quasiparticle bound states at the interface boundary and the gap‐like structure of the conductance depending on the orientation of the junction are obtained and the role of the Andreev reflection in identifying the pairing symmetry in the odd‐parity superconductors is also discussed.
Non‐ergodicity of the 1D Heisenberg model
Authors: Bak M. , Avella A. , Mancini F.
Published: March 2003

The relevance of zero‐energy functions, coming from zero‐energy modes and present in the structure of bosonic Green's functions, is often underestimated. Usually, their values are fixed by assuming the ergodicity of the dynamics, but it can be shown that this is not always correct. As the zero‐energy functions are connected to fundamental response properties of the system under analysis (specific heat, compressibility, susceptibility, etc.), their correct determination is not an irrelevant issue. In this paper we present some results regarding the zero‐energy functions for the Heisenberg chain of spin‐1/2 with periodic boundary conditions as functions of the number of sites, temperature, and magnetic field. Calculations are pursued for finite chains, using equations of motion, exact diagonalization and Lanczos technique, and the extrapolation to the thermodynamic limit is studied.
Effect of randomness on superconductivity and CDWin the (hard‐core) boson‐fermion model
Authors: Pawłowski G. , Robaszkiewicz S.
Published: March 2003

We discuss the influence of diagonal disorder (random site energy) on superconductivity (SC) and charge orderings (CDW) in a system of coexisting itinerant electrons and local pairs, described by the (hard‐core) boson‐fermion model. The evolution of the ground state properties and critical temperatures with increasing disorder is analysed. One finds that both the SC and the CDW can be substantially suppressed by the disorder effects. This is in obvious contrast with the s‐wave BCS superconductors which, according to the Anderson's theorem, are rather insensitive to the diagonal disorder (i.e. to nonmagnetic impurities).
The variational approach to the superconductivity in the Holstein–Hubbard model
Authors: Grzybowski P. , Micnas R.
Published: March 2003

We examine the variational squeezed‐state and the correlated squeezed‐state approach to the ground state of the Holstein–Hubbard model in the case of strong electron–phonon interaction, paying special attention to the electron–hole symmetry of the model Hamiltonian. We have found differences with respect to the results previously reported for the normal and superconducting phases, and present an improved analysis.
Monte Carlo Simulations of the 3D Ashkin–Teller Model: continuous phase transition lines
Authors: Musiał G. , Dębski L. , Kamieniarz G.
Published: March 2003

Large‐scale Monte Carlo simulations, based on the invariance of the Binder cumulant Q, for continuous phase transitions in the three‐dimensional Ashkin–Teller spin‐lattice model on a cubic lattice, have been performed. Using the universality hypotesis and the finite‐size‐scaling analysis, the Ising character of phase transitions from the antiferro‐ to paramagnetic phase, where the cumulant Q behavior is different than in the Ising model, is demonstrated. Some preliminary results demonstrating the existance of the tricritical points are also presented.
Specific features in magnetic resistivity of RFe11Ti single crystals
Authors: Tereshina I. S. , Nikitin S. A. , Bezkorovajnaja G. A. , Suski W. , Badurski D.
Published: March 2003

Magnetic resistivity ρ and its anomalies in the vicinity of spin‐reorientation transitions (SRT) in single crystals of RFe11Ti (R = Y, Dy, and Er) are investigated in the temperatures range 4.2–130 K and in magnetic fields up to 8 T. Anomalous increases of magnetization σ(B) and ρ(B) are obtained for DyFe11Ti when a field of about 1–2 T is applied along the [001] axis at a temperature in the range 4.2–130 K. ErFe11Ti shows an SRT at T = 50 K from the c‐axis to a non‐collinear magnetic structure at low temperatures which also result in a sharp increase of ρ(B) at low magnetic fields.
Adiabatic sound velocity in the vicinity of phase transition in magnets
Authors: Pawlak A.
Published: March 2003

The Ginzburg‐Landau Hamiltonian of a magnetic system, containing magneto‐elastic as well as entropo‐elastic interactions in addition to usual magnetic ones, is considered in detail. Adiabatic longitudinal sound velocity is defined by the pressure correlation function and is found to be finite at the phase transition temperature in contrast to the behaviour of the isothermal sound velocity which goes asymptotically to zero. A weakly‐singular contribution to adiabatic sound velocity is also found. We show that it can be expressed entirely in terms of the static spin‐energy vertex function evaluated with an effective spin Hamiltonian. For the Ising‐type magnets the vertex function is found to exhibit a (T–TC)α singularity.
On–off intermittency and attractor bubbling in the Ising‐like cellular automaton with temperature random in time
Authors: Stępień L. , Krawiecki A. , Kosiński R. A.
Published: March 2003

The Ising‐like cellular automaton with global ferromagnetic coupling and parallel thermal bath dynamics is considered, with uniform in space temperature varying randomly in time in the neighbourhood of the critical point. The system is studied both by numerical simulations with a large number of spins, and analytically in the mean field approximation. The time series of magnetisation show a sequence of laminar phases during which the magnetisation is close to zero, corresponding to paramagnetic phase, and large bursts with non‐zero magnetisation, corresponding to abrupt occurrence of ordered phase. It is shown that this behaviour is an example of on‐off intermittency and attractor bubbling, which appear as collective phenomena due to interaction of a large number of spins subject to random temperature.
Finite‐temperature quantum transfer‐matrix simulations of the frustrated spin 1/2 chains: comparison with experiment
Authors: Bieliński M. , Kamieniarz G. , Szukowski G. , Baran M. , Gladczuk L. , Szymczak H.
Published: March 2003

This article presents the thermodynamical properties of quasi‐one dimensional magnetic systems CuGeO3 and new obtained Pb[Cu(SO4)(OH)2] evaluated by the numerically exact quantum transfer‐matrix method. Numerical results calculated for an infinite system and for a finite‐chain structure are compared successfully with experimental magnetic susceptibility data.