bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Sampling Strategy on Microbiologic Results Before and After Periodontal Treatment
Authors: Casas Agustín , Herrera David , Martín‐Carnes Javier , González Itziar , O'Connor Ana , Sanz Mariano
Published: May 2007

Background: The aim of this study was to test whether different sampling strategies would influence the microbiologic outcomes by assessing the bacterial load and composition of the subgingival microbiota by means of anaerobic culturing before and after periodontal treatment.

Methods: The first study (1 versus 4 [1vs4]) included 33 patients with generalized chronic periodontitis. Two sampling strategies were compared, sampling one site from the deepest pocket in the mouth (M1) versus a pooled sample of four sites from the deepest pockets in each quadrant (M4). The second study (2 versus 4 [2vs4]) included 20 patients with generalized chronic periodontitis. The strategy M4 was compared to a pooled sample of two non‐adjacent sites in the same quadrant (M2). All samples were processed identically by means of anaerobic culturing. In both studies, a pretreatment sampling was taken. However, in the second study (2vs4), subgingival samples were also taken at 1, 3, and 6 months after periodontal therapy. Quantitative data were compared between strategies by means of t test and signed‐rank test; qualitative data were compared by means of 2 × 2 contingency tables.

Results: Pretreatment samples showed that total anaerobic counts were significantly higher for M4 compared to M1 (P <0.001) and M2 (P = 0.025). However, there were no significant differences in regard to percentage of microbiota and counts for each pathogen. Most of the qualitative differences between strategies were caused by false negatives in M1 and M2. Post‐treatment samples showed a reduction in total counts and a limited impact in the frequency of detection of periodontal pathogens. M2 detected a significant decrease in the frequency of detection of Porphyromonas gingivalis, which was not confirmed by the M4 strategy.

Conclusion: The criteria of selection and the number of sites selected when sampling the subgingival biofilm in patients with generalized chronic periodontitis may influence the detection and quantitation of periodontal pathogens when evaluated by culture especially after treatment.
The Additional Effect of a Dentifrice on the Instant Efficacy of Toothbrushing: A Crossover Study
Authors: Paraskevas S. , Rosema N.A.F. , Versteeg P. , Timmerman M.F. , van der Velden U. , van der Weijden G.A.
Published: May 2007

Background: Inconclusive evidence exists in the literature with regard to the additional (beneficial) mechanical effect of a dentifrice on plaque removal. A previous split‐mouth study found that a dentifrice did not contribute to plaque removal. Because of limitations of the split‐mouth model, a crossover design was used to evaluate whether a commercially available dentifrice had an additional effect on mechanical plaque removal during manual toothbrushing.

Methods: Thirty‐six subjects were given a manual toothbrush and a standard dentifrice. After a 48‐hour plaque accumulation, subjects brushed under supervision with or without a dentifrice (total time of 2 minutes) in a 2 × 2 crossover design.

Results: Plaque reductions were 50% with and 56% without the use of dentifrice. This 6% difference was statistically significant (P = 0.034). Explorative analysis showed that brushing without a dentifrice was more effective in removing plaque on the approximal surfaces.

Conclusions: The use of a dentifrice did not contribute to mechanical plaque removal during manual toothbrushing. It seemed that the mechanical action provided by the toothbrush was the main factor in the plaque‐removing process.
Radiographic Study of Ethnic Variation in Alveolar Bone Height Among New Zealand Dental Students
Authors: Wong Benedicta K.J. , Leichter Jonathan W. , Chandler Nick P. , Cullinan Mary P. , Holborow Doug W.
Published: May 2007

Background: The aim of this study was to determine anatomical variations in the radiographic distance between the cemento‐enamel junction and the alveolar crest with respect to ethnic heritage and gender in New Zealand dental students.

Methods: Digitized bitewing films of 123 second‐year New Zealand dental students were examined with a computer imaging program on a desktop computer screen. The race of parents and grandparents was obtained by questionnaire.

Results: The mean distance from the cemento‐enamel junction to the alveolar crest across the sample was 0.97 mm. Eighteen (14.6%) of the participants had measurements >2 mm, of whom 17 were Asians. Asians had a significantly larger mean distance than did non‐Asians (1.10 mm compared to 0.83 mm; P <0.001). Gender was not a significant variable.

Conclusions: Students of Asian origin had a significantly greater distance between the cemento‐enamel junction and the alveolar crest. It remains to be determined whether this is anatomical or disease related.
Excessive Gingival Bleeding in Two Patients With Glanzmann Thrombasthenia
Authors: Toygar Hilal Uslu , Guzeldemir Esra
Published: May 2007

Background: Glanzmann thrombasthenia (GT) is an exceedingly rare but well‐defined inherited disorder of platelet function caused by a defect in the glycoprotein IIb/IIIa complex. The association of GT with consanguinity has been noted, especially in geographic regions in which intermarriage is common. In most patients, GT is diagnosed during early infancy or before the age of 5 years. Common manifestations of this disorder are gingival hemorrhage, purpura, epistaxis, petechiae, and menorrhagia. Chronic, prolonged, untreated, or unsuccessfully treated bleeding may be life threatening.

Methods: We report two female patients with GT who were referred by our hematology clinic to our periodontology department for the treatment of excessive gingival bleeding. The first patient was treated with a platelet transfusion and underwent periodontal therapy (scaling and root planing and dental polishing). The second patient, whose GT was undiagnosed at the time of her referral to our department, applied to our emergency service because of uncontrolled gingival bleeding that developed after scaling and root planing was performed by her dentist. Both patients had been called for regular dental visits.

Results: All treated sites healed without complications. The first patient was monitored for 2 years, during which she practiced proper oral hygiene and experienced no periodontal complications. The other patient did not participate in follow‐up.

Conclusions: Gingival bleeding is usually the first sign of most hematologic disorders, and dentists must be alert for the signs of unusual gingival bleeding. In such cases, collaboration with a hematologist is essential. Under the proper circumstances, periodontal treatment can be performed with an acceptable outcome. With proper oral hygiene, we believe that there will be no complications and no gingival bleeding.
Securing Maternal Health Through Comprehensive Reproductive Health Services: Lessons from Bangladesh
Authors: Jahan Rounaq
Published: May 2007

During the past decade, there has been a noticeable reduction of maternal mortality in Bangladesh, in part because of government policy and program initiatives. Of particular note is the comprehensive reproductive health strategy adopted in 1996 under the country’s first Health and Population Sector Strategy and the 5-year Health and Population Sector Programme (1998–2003). The latter includes actions in most of the areas recommended in the World Health Organization’s 2004 report, Reproductive Health Strategy to Accelerate Progress Towards the Attainment of International Development Goals and Targets. After assessing Bangladesh’s achievements and challenges in the design and implementation of a maternal health strategy, I concluded that mobilizing and nurturing political will is the key to sustaining policy commitment to comprehensive reproductive health.
Overt and Subtle Racial Discrimination and Mental Health: Preliminary Findings for Korean Immigrants
Authors: Noh Samuel , Kaspar Violet , Wickrama K.A.S.
Published: May 2007

Objectives. We examined differential effects of overt and subtle forms of racial discrimination on 2 dimensions of mental health—positive affect and depressive symptoms, and explored the mediating roles of emotional arousal and cognitive appraisal.

Methods. Cross-sectional survey data were collected through face-to-face interviews with a sample (N=180) of adult Korean immigrants living in Toronto, Ontario. Maximum likelihood estimates of path coefficients were obtained using structural equation models.

Results. Perceived racial discrimination was associated with both the erosion of positive affect and depressive symptoms. Overt discrimination was associated with the erosion of positive affect, and subtle discrimination was associated with depressive symptoms. Effects of subtle discrimination on depressive symptoms were mediated through cognitive appraisal.

Conclusions. The results emphasize the salience of subtle discrimination for the mental health of Asian immigrants. Experiences of overt racial bias seemed to be of little importance for the levels of depressive symptoms among those in our sample, although the experience of blatant discrimination tended to reduce positive mood.
The Impact of Safer Breastfeeding Practices on Postnatal HIV-1 Transmission in Zimbabwe
Authors: Piwoz Ellen G. , Humphrey Jean H. , Tavengwa Naume V. , Iliff Peter J. , Marinda Edmore T. , Zunguza Clare D. , Nathoo Kusum J. , Mutasa Kuda , Moulton Lawrence H. , Ward Brian J.
Published: May 2007

Objectives. We assessed the association between exposure to an educational intervention that emphasized safer breastfeeding practices and postnatal HIV transmission among 437 HIV-positive mothers in Zimbabwe, 365 of whom did not know their infection status.

Methods. Mothers were tested for HIV and were encouraged—but not required—to learn their HIV status. Intervention exposure was assessed by a questionnaire, Turnbull methods were used to estimate postnatal HIV transmission, and multivariate Cox proportional hazard models were constructed to assess the association between intervention exposure and postnatal HIV transmission.

Results. Cumulative postnatal HIV transmission was 8.2%; each additional intervention contact was associated with a 38% reduction in postnatal HIV transmission. HIV-positive mothers who were exposed to both print and video materials were 79% less likely to infect their infants compared with mothers who had no exposure. These findings were similar for mothers who did not know their HIV status.

Conclusions. The promotion of exclusive breastfeeding has the potential to reduce postnatal HIV transmission among women who do not know their HIV status, and child survival and HIV prevention programs should support this practice.
Circumstances of First Injection Among Illicit Drug Users Accessing a Medically Supervised Safer Injection Facility
Authors: Kerr Thomas , Tyndall Mark W. , Zhang Ruth , Lai Calvin , Montaner Julio S.G. , Wood Evan
Published: May 2007

There have been concerns that safer injecting facilities may promote initiation into injection drug use. We examined length of injecting career and circumstances surrounding initiation into injection drug use among 1065 users of North America’s first safer injecting facility and found that the median years of injection drug use were 15.9 years, and that only 1 individual reported performing a first injection at the safer injecting facility. These findings indicate that the safer injecting facility’s benefits have not been offset by a rise in initiation into injection drug use.
The Influence of Social Context on Changes in Fruit and Vegetable Consumption: Results of the Healthy Directions Studies
Authors: Sorensen Glorian , Stoddard Anne M. , Dubowitz Tamara , Barbeau Elizabeth M. , Bigby JudyAnn , Emmons Karen M. , Berkman Lisa F. , Peterson Karen E.
Published: May 2007

As part of the Harvard Cancer Prevention Program Project, we used a social contextual model of health behavior change to test an intervention targeting multiple risk-related behaviors in working-class, multiethnic populations. We examined the relationships between the social contextual factors in our conceptual model and changes in fruit and vegetable consumption from baseline to completion of intervention in health centers and small business studies. We analyzed change in fruit and vegetable consumption, measured at baseline and final assessments by self-report, in 2 randomized controlled prevention trials: 1 in small businesses (n = 974) and 1 in health centers (n = 1954).

Stronger social networks, social norms that were more supportive, food sufficiency, and less household crowding were associated with greater change in fruit and vegetable intake. We also observed differences between our intervention sites. Social context can play an important role in promoting changes in fruit and vegetable consumption.
The Political Economy of Marriage and HIV: The ABC Approach, “Safe” Infidelity, and Managing Moral Risk in Uganda
Authors: Parikh Shanti A.
Published: May 2007

Research has shown that married women’s greatest risk for HIV infection is their husbands’ extramarital sexual activities. Using 6 months of ethnographic research in southeastern Uganda, I examined how the social and economic contexts surrounding men’s extramarital sexuality and the dynamics of marriage put men and women at risk for HIV infection.

I found that Uganda’s HIV prevention messages may be inadvertently contributing to increased difficulty in acknowledging HIV risk and to newer forms of sexual secrecy and that structural determinants, including persistent poverty, intersect with gender inequalities to shape marital risk. After examining a community effort to regulate men’s sexuality, I suggest that HIV prevention strategies should focus more on endogenous forms of risk reduction while simultaneously addressing structural factors that facilitate opportunities for men’s extramarital sex.
Perpetration of Intimate Partner Violence Among Men in Methadone Treatment Programs in New York City
Authors: El-Bassel Nabila , Gilbert Louisa , Wu Elwin , Chang Mingway , Fontdevila Jorge
Published: May 2007

This study examined the prevalence of perpetration of intimate partner violence among 356 men recruited from methadone maintenance treatment programs. We used logistic regression with covariance adjustment to examine the associations between intimate partner violence and illicit drug use by the participants, their female partners, or both. We found a high prevalence of intimate partner violence among the men in our sample. Significant associations between intimate partner violence and illicit drug use varied by types of drugs and whether the female partner or both partners were using drugs.
Rethinking Mandatory HIV Testing During Pregnancy in Areas With High HIV Prevalence Rates: Ethical and Policy Issues
Authors: Schuklenk Udo , Kleinsmidt Anita
Published: May 2007

We analyzed the ethical and policy issues surrounding mandatory HIV testing of pregnant women in areas with high HIV prevalence rates. Through this analysis, we seek to demonstrate that a mandatory approach to testing and treatment has the potential to significantly reduce perinatal transmission of HIV and defend the view that mandatory testing is morally required if a number of conditions can be met.

If such programs are to be introduced, continuing medical care, including highly active antiretroviral therapy, must be provided and pregnant women must have reasonable alternatives to compulsory testing and treatment. We propose that a liberal regime entailing abortion rights up to the point of fetal viability would satisfy these requirements.

Pilot studies in the high-prevalence region of southern African countries should investigate the feasibility of this approach.
Mechanistic studies on the effect of veratryl alcohol on the lignin peroxidase catalyzed oxidation of pyrogallol red in reversed micelles
Authors: Lan Jing , Huang Xirong , Hu Ming , Liu Weifeng , Li Yuezhong , Qu Yinbo , Gao Peiji
Published: May 2007

The lignin peroxidase (LiP) catalyzed oxidation of pyrogallol red (PR) in the absence and presence of veratryl alcohol (3,4-dimethoxybenzyl alcohol, VA) was carried out in bis (2-ethylhexyl) sulfosuccinate sodium (AOT)/ polyoxyethylene lauryl ether (Brij30) reversed micelles to elucidate the role of VA. Results indicated that VA could accelerate the LiP catalyzed oxidation of PR, especially at low H2O2 concentrations. Unlike in bulk aqueous medium, the protection of LiP by VA in the present medium was relatively unsubstantial, even at high H2O2 concentrations. Analysis of data from a series of experiments showed that the enhancement of the PR oxidation caused by VA was mainly due to the indirect oxidation of PR by VA+∙ from the LiP catalyzed oxidation of VA. It was also found that at the same protector concentration (40 μM), VA (the physiological substrate of LiP) was less effective than PR (a phenolic compound) in protecting LiP from the H2O2 derived inactivation. This novel phenomenon deserves further study.
Possible association of the pro‐melanin‐concentrating hormone gene with a greater body mass index as a side effect of the antipsychotic olanzapine
Authors: Chagnon Y.C. , Bureau A. , Gendron D. , Bouchard R.H. , Mérette C. , Roy M.‐A. , Maziade M.
Published: May 2007

Following our report of a linkage at 12q24 with a phenotype of obesity under antipsychotics, we tested the pro‐melanin‐concentrating hormone (PMCH) candidate gene for a possible association in humans with the body mass index (BMI; kg/m2) in unrelated schizophrenic patients (SZ) receiving antipsychotics (N = 300) and in controls (CTL; N = 150). Subjects were classified in obese (OB) (BMI ≥ 30 kg/m2), overweight (25 ≤ BMI < 30 kg/m2), and normal weight (BMI < 25 kg/m2) groups. Single nucleotide polymorphisms (SNP) rs7973796 and rs11111201, located 5′ at −4.5 kb and 3′ at +1.8 kb, respectively, of PMCH were genotyped. Interaction effects of genotypes and antipsychotic treatment on BMI were tested in a covariance analysis with age and gender as covariates. Interaction effects on the prevalence of obesity were tested in a logistic regression analysis. For subjects under 50 years, the effect of the rs7973796 genotype on BMI differed between the SZ patients taking olanzapine and CTL group (interaction P = 0.025). Olanzapine‐treated SZ patients carrying the ancestral homozygote genotype showed a higher BMI for rs7973796 (P = 0.016 with the LSMeans t‐test) than the variant homozygotes. Accordingly, the ORs for obesity associated with rs7973796 genotypes differed in the SZ patients taking olanzapine compared to the CTL group (interaction P = 0.0094). The G allele was associated with an increase in the odds of obesity in SZ patients taking olanzapine. No association was observed for those over 50 years, or for rs11111201. These results suggest that the common allele of PMCH rs7973796 may be associated with a greater BMI in olanzapine‐treated SZ patients. © 2007 Wiley‐Liss, Inc.
Zur negativen Zeitentwicklung bei der kernmagnetischen Resonanz in Festkörpern
Authors: Schmiedel H. , Schneider H.
Published: May 2007

Die Möglichkeit der Realisierung eines effektiven Hamiltonoperators, der sich von einem bekannten anderen nur durch das Vorzeichen unterscheidet, wird diskutiert. Diese ergibt sich bei Spinsystemen im Festkörper und führt zu einer “negativen Zeitenwicklung”. Verschiedene Impulsverfahren, die das ermöglichen, werden erläutert. Der Charakter dieses Phänomens wird an Hand des Spin‐Temperatur‐Konzeptes und von Vielteilchenoperatoren diskutiert. Anwendungsmöglichkeiten zur Bestimmung des 2. Momentes sowie zum Studium langsamer thermischer Bewegungen werden angedeutet.
Investigation of the Reaction 9Be(d, t0)8Be in the Deuteron Energy Range 0.9÷2.5 MeV
Authors: Bondouk I. I. , Asfour F. , Machali F.
Published: May 2007

The reaction 9Be (d, t0) 8Be has been investigated in the deuteron energy range 0.9 ÷ 2.5 MeV. The excitation functions were measured at laboratory angles 45° and 120° and showed no sharp resonances. The angular distributions (differential cross sections in mb/sr) were measured in 200 keV intervals. An analysis of the data has been made using the Butler and the distorted wave theories.
An DWBA Analysis of the Angular Distribution and Polarization of Neutrons from the Reaction 12C(d, n0)13N in the Deuteron Energy Range 1.7–2.8 MeV
Authors: Bondouk I. I.
Published: May 2007

The angular distribution and the polarization of neutrons from the reaction 12C(d, n0)13N in the deuteron energy range 1.7–2.8 MeV have been analyzed in terms of the DWBA theory.
On the Reconstructability of Ensembles by Measurements
Authors: Seeberg O.
Published: May 2007

A formal division of ensembles into pure ensembles is interpreted in physical terms. If the division of an ensemble can be generated by measurement of all properties, then the ensemble is called reconstructable. It is investigated in which cases an ensemble is reconstructable. Furthermore the hypothesis of random phases is discussed.
Die Erhaltung der Teilchenzahlen in der allgemeinen Relativitätstheorie
Authors: Treder H.‐J.
Published: May 2007

Gilt in einer speziell‐relativistischen Feldtheorie ein Erhaltungssatz für die Teilchenzahl als Konsequenz der Divergenzfreiheit eines Teilchenstroms, dann gilt derselbe Erhaltungssatz auch in der allgemeinen Relativitätstheorie.
Differential Cross‐Section for Excitation of Helium by Electron from Field Theoretic View Point
Authors: Roy T. , Bhattacharyya S.
Published: May 2007

Cross‐section for excitation of helium from ground state to 2s singlet state is computed by field theoretic methods. Comparisons are made with experimental and Born cross‐sections. Field theoretic cross‐section is found to be in good agreement with experimental results for all ejection angles.
Some Methodological Problems in Quantum Physics
Authors: Mayants L. S. , Yourgrau W. , van Der Merwe A. J.
Published: May 2007

A consistent application of probabilistic theory is able to resolve traditionally perplexing quantum‐theoretical issues, such as those concerned with quantum measurement procedures, wave‐corpuscle duality, the reality of particle motion, hidden variables, the proper choice of the energy operator, the energy‐time uncertainty relation, conservation laws, and the notion of wave packets. Germane to this resolution is the consideration that quantum physics deals with abstract physical systems and not with single measurements performed on concrete systems. We examine the two‐slit diffraction phenomenon and those hypothetical experiments which attempt the simultaneous measurement of any coordinate and its conjugate momentum; their customary interpretations are shown to be basically incorrect. A logical error is likewise found to underlie the usual assertion that the ordinary rule for the addition of probabilities breaks down in quantum physics. And the confusion of energy with the Hamiltonian function is identified as the cause for a number of prevailing wrong conclusions. The probabilistic approach furthermore invalidates PAULI'S proof that time is a socalled c‐number. Our treatment also readily exposes the fallacy in the common assumption that Schrödinger's wave equation goes over into the Hamilton‐Jacobi equation when the classical limit is approached.
Photo‐Production of Muons
Authors: El‐Khishen M. , Allam S. H.
Published: May 2007

The total cross‐section for the photo‐production of muons in the reaction γ + e− → μ− + ve + vμ is calculated. The dependence of the total cross‐section on the incident photon energy is explicitly shown.
Lepton‐Lepton Interactions under a Strong Magnetic Field
Authors: El‐Khishen M. , El‐Lakani A. , El‐Gowhari A.
Published: May 2007

The cross‐section for the reaction e+ + e− → v + v, under a strong magnetic field is calculated. The rate of energy loss is also calculated. These calculations may be of great importance for astrophysical estimations in neutron stars.
The O'RAIFEARTAIGH Theorem for the Generalized Lie Algebras
Authors: Kosiński P. , Rembieliński J. , Maślanka P.
Published: May 2007

The generalization of O'RAIFEARTAIGH'S theorem about mass splitting to the case of an algebra containing both commutators and anticommutators is given.
Rising Inelastic Cross Section and its Contribution to Steepening of the Cosmic Ray Energy Spectrum
Authors: Rao Y. V.
Published: May 2007

Calculations have been carried out to investigate the contribution of an increasing total cross section to steepening of the cosmic ray energy spectrum at very high energies (E ≳ 1012 eV). Our results suggest that increasing total cross section contributes only a part to the steepening of primary energy spectrum at very high energies even if the composition is pure primary iron flux.
Fermion Fields in Theories of Gravitation
Authors: Kasper U.
Published: May 2007

After an introduction to the formalism used throughout the paper there follows a concise presentation of the theory of fermion fields in one‐tetrad gravitational theories. That presentation gives a hint to the construction of a bi‐tetrad theory, the two tetrad fields being denoted by hAk and h̄Ak. The tetrad field hAk. gives the Riemannian metric gkl while the tetrad field h̄hAk is orthonormalized with respect to the flat metric akl. Specializing h̄Ak in such a way that they have the form δAk in the preferred coordinates of Minkowski space and using a matter Lagrangian which contains these h̄Ak only by the anholonomic components of the metric Christoffel symbols, we obtain a dynamical energy momentum tensor which is equal to the canonical one. Then we consider the relations of the bi‐tetrad theory to other theories which are only covariant with respect to global Lorentz transformations from the beginning. As an example we formulate the main relations of the two‐component neutrino theory.
Über die Existenz von Entropiefunktionen in Nichtgleichgewichtszuständen chemischer Reaktionssysteme I
Authors: West G.
Published: May 2007

Für chemische Reaktionsprozesse und Energie‐Austauschprozesse zwischen inneren Energieniveaus eines Systems werden Axiome für die Reaktionskinetik mit Hilfe der Reaktionslaufzahlen und Reaktionsinvarianten formuliert. Das Axion der asymptotischen Stabilität führt auf die in Teil II dieser Arbeit dargelegte Existenz von Entropiefunktionen in Nichtgleichgewichtszuständen.
Selektion eines Pikosekundenimpulses aus einem lmpulszug mit Hilfe von sättigbaren Absorbern und Absorption in angeregten Zuständen
Authors: Herrmann J. , Weidner F.
Published: May 2007

Es wird die Absorption von Impulsen eines Impulszuges unter der kombinierten Einwirkung eines sättigbaren Einphotonenabsorbers (im Grundzustand) und eines Einphotonenabsorbers (nach Zweiphotonenabsorption) im angeregten Zustand berechnet. Für verschiedene Absorberanordnungen geltende Bilanzgleichungssysteme werden gelöst und die Selektionsmöglichkeiten dafür untersucht.
Anwendung der GRYZINSKY‐Theorie zur Berechnung der Ionisierungs‐ und Umladungwirkungsquerschnitte für die Wechselwirkung von Wasserstoffionen und Alkanolmolekülen
Authors: Mach R. , Drost H. , Behlke H. , Spangenberg H.‐J.
Published: May 2007

Die Ionisierungs‐ und Umladungswirkungsquerschnitte wurden für die Wechselwirkung von H+‐, H‐, und H‐ Ionen (Ionenenergie 5‐25 keV) mit den Alkanolen vom Methanol bis zum Butanol nach einer modifizierten GRYZINSKY‐Theorie berechnet. Ein Vergleich mit experimentell ermittelten Wirkungsquerschnitten ergab insgesamt eine zufriedenstellende Übereinstimmung.
Periodische Stromabweichungen bei Photofeldemission aus Wolfram und ihre Wellenlängenabhängigkeit
Authors: Radoń T. , Kleint Ch.
Published: May 2007

Es wird über weitere Untersuchungen der bei Photofeldemission gefundenen kurzperiodischen Stromabweichungen berichtet, die im Ultrahochvakuum unter Feldemissionsbedingungen mit modulierter monochromatischer Anregung durch Hg‐Linien gemessen wurden. Zur quantitativen Auswertung der durch statistische Stromfluktuationen beeinflußten Charakteristiken werden neben den Kennlinien auch Korrelationsdiagramme und ‐koeffizienten sowie die Mittelwerte der Perioden herangezogen. ‐ Es zeigte sich, daß die Periodizitäten nur wenig von der Anregungsenergie hv abhängen und sich mit verschiedenem hv reproduzieren lassen, dß sie in einem großen Feldstärkebereich beobachtbar sind und daß ein schwebungsartiger Verlauf auftritt.

Zur Erklärung der Periodizitäten wird ein Modell vorgeschlagen, wonach durch ein Adsorbat die Potentialbarriere an der Oberfläche so abgeändert wird, daß partielle Reflexionen der Elektronenwellen auftreten können. Eine ähnliche Vorstellung wurde von ALFERIEFF und DUKE zur Deutung der Jason‐Resonanzen bei Feldionisation durchgerechnet und diskutiert, eine formale Verwandtschaft besteht auch zur Erklärung der Tunnelstromperiodizitäten von MOS‐Strukturen.
Nucleon Isobar Production in Proton‐Nucleon Collision at 6 GeV/c Incident Proton Momentum
Authors: Badawy O. E. , Abdo K. M. , Hussein M. T.
Published: May 2007

Angular and momentum distributions as well as grain densities of charged secondaries emitted in inelastic proton‐nucleon interactions are measured. The cross‐section of the Δ (1236) isobar production in the events of the type pp →pnπ+ is calculated. The theoretical predictions of both the isobar and the O.P.E. model are compared with the experimental data. The transverse momentum distribution of both pions and protons is presented and explained by various theoretical models.
A Method of Calculating the Density Matrix for a System of Interacting Bosons in Coherent‐state Basis
Authors: Trung T. V. , Schütte F.‐J.
Published: May 2007

The time‐dependent behaviour of a system of several interacting boson modes is described in coherent state basis. In the Schrödinger picture the unitary time development operator is used. The variation of the density operator for the whole system is described for arbitrary situations (even such without P‐representation).

The method is applied to the parametric amplification process with strong pump field.
Einfluß des Randes auf das effektive Verhalten heterogener Körper ‐ Anwendung auf Rayleighwellen
Authors: Bahr Ute
Published: May 2007

Für die elastische Oberflächenwelle vom Rayleightyp in einem heterogenen Material (z. B. Gemisch aus mehreren Phasen, Verbundwerkstoff, Polykristall) werden die Wellen gleichung und Randbedingungen nach den selben störungstheoretischen Methoden, die für unendlich ausgedehnte heterogene Körper angewendet werden, hergeleitet. Diese Wellengleichung ist eine Integrodifferentialgleichung, was zur Folge hat, daß die Ausbreitungsgeschwindigkeit der Oberflächenwelle vs frequenzabhängig wird. Außerdem sind die Wellen gedämpft.

Unter vereinfachenden Voraussetzungen (Isotropie, nichtstochastische elastische Konstanten) wird folgendes gezeigt: Beschränken sich die Dichtefluktuationen auf die Randnähe, so verhält sich der frequenzabhängige Teil der Ausbreitungsgeschwindigkeit wie \documentclass{article}\pagestyle{empty}\begin{document}$ \frac{{l^3 \omega ^3}}{{{\mathop c\limits^\circ} _t^3}} $\end{document} und die Dämpfung wie \documentclass{article}\pagestyle{empty}\begin{document}$ \frac{{l^4 \omega ^5}}{{{\mathop c\limits^\circ} _t^5}} $\end{document}, während sich bei Dichtefluktuationen im gesamten Halbraum \documentclass{article}\pagestyle{empty}\begin{document}$ \frac{{l^2 \omega ^2}}{{{\mathop c\limits^\circ} _t^2}} $\end{document} und \documentclass{article}\pagestyle{empty}\begin{document}$ \frac{{l^3 \omega ^4}}{{{\mathop c\limits^\circ} _t^4}} $\end{document} ergibt. Hieraus wird ersichtlich, unter welchen Umständen die Wellen hinreichend durch eine Differentialgleichung mit frequenzabhängiger Massendichte beschrieben werden können.
On a Generalization of Hilbert's Metrical Matter Tensor in Einstein's Field Equations
Authors: Treder H.‐J.
Published: May 2007

We construct a new source tensor T̂ik in Einstein's equations of gravitation. This matter tensor is a generalization of Hilbert's “metrical energy‐momentum tensor” Tik.
Depolarized Light Scattering from Paramagnetic Liquids in a Magnetic Field
Authors: Malomush N. P. , Latushkin S. D. , Gründer K.‐P.
Published: May 2007

In order to identify spectral features and molecular movement types the magnetic field's influence on rotational and diffuse shear modes of paramagnetic liquids is analysed. Consideration of the corresponding changes in depolarized (VH) light scattering spectra illustrates a systematic method of studying both paramagnetic and diamagnetic liquids.
Equations of Motion for Test Particles with Internal Structure
Authors: Fuchs Helmut
Published: May 2007

The general structure of equations of motion for test particles is considered with the help of a Lagrangian principle postulating a minimal coupling between internal and external variables. As an example the case of the Lorentz group as the basic internal group is considered in more detail. The connection with the Mathisson‐Papapetrou equations is established.
On Singularities of General Relativity and Gravitational Equations of Fourth Order
Authors: v. Borzeszkowski H.‐H.
Published: May 2007

Comparing Einstein's gravitational equations and equations containing fourth‐order derivative corrections we discuss some aspects of singularities of spherically symmetric static vacuum solutions from the point of view, first, of the coupling to non‐gravitational matter and, second, of the Einsteinian classical particle programme.
Paritätsverletzende Asymmetrie bei der Erzeugung zweier Jets bei Stößen polarisierter Protonen infolge der Interferenz der starken und schwachen Wechselwirkung
Authors: Ranft Gisela , Ranft Johannes
Published: May 2007

Durch die schwache Wechselwirkung und die Interferenz der schwachen und starken Wechselwirkung treten paritätsverletzende Spin‐Spin‐Asymmetrien bei der Streuung polarisierter Hadronen auf. Bei Stößen von Hadronen mehrerer hundert GeV erreichen diese Asymmetrien Werte von einigen Prozent und sind damit experimentell nachweisbar. Die Größe und Form der Asymmetrien gibt Auskunft über den schwachen Mischungswinkel sin2θWund die Strukturfunktionen polarisierter Quarks in polarisierten Hadronen.
Ein einfaches Modell für ein an einer isoelektronischen Störstelle schwach gebundenes Exziton
Authors: Geistlinger H. , Weller W.
Published: May 2007

Es wird ein Variationsverfahren angegeben, das die Bindung eines Exzitons an einer isoelektronischen Störstelle für den gesamten Bereich von starker Bindung bis zum freien Exziton beschreibt. Betrachtet wird ein direkter oder indirekter Halbleiter mit einem Leitungs‐ und einem Valenzband, für die Störstelle wird Einzentrennäherung verwendet. Der zentrale Teil der Elektronwellenfunktion wird ohne Effektive‐Masse‐Näherung behandelt. Der Bereich schwacher Bindung wird durch Entwicklung um den Grenzfall des freien Exzitons ausführlich diskutiert, dabei ergibt sich auch noch Bindung des Exzitons in einem kleinen Gebiet oberhalb der Potentialschwelle für Bindung des Elektrons.
The Equation of State for the Hydrogen Plasma on Account of Atom‐Atom Interaction
Authors: Schlanges M. , Kremp D.
Published: May 2007

The equation of state for the hydrogen plasma is investigated quantumstatistically in the case of chemical equilibrium between electrons protons, H‐atoms and H2‐molecules. In order to take into account the formation of H2‐molecules it is necessary to know the fourth cluster coefficient. For the numerical calculation a pair approximation of the fourth cluster coefficient is given on the basis of the many‐channel scattering theory.
Zur Kosmologie der unitären Feldtheorie mit gravo‐elektrischer Induktion
Authors: Kreisel Eckhard
Published: May 2007

Für den Robertson‐Walkerschen Ansatz existiert in der unitären Feldtheorie mit gravo‐elektrischer Induktion nur der Minkowski‐Raum als Lösung. Erst bei Einführung von phänomenologischer Staubmaterie erhält man als Lösung Einstein‐de Sitter‐Kosmen.
Non‐Linear Kinematics of Line‐Structures
Authors: Günther H.
Published: May 2007

In a preceding paper [3] we have formulated a geometrical theory of structural defects for a very large classe of materials e. g. ordinary crystals, line structured materials as polymers and others. The application to a special kind of material requires a physical interpretation of the geometrical terms for this material. Referring to the papers of ANTHONY [1, 2], we give here a generalization of the geometrical theory of line structures, that is comprising a general internal motion of the material including the motion of defects. In order to do this the theory is to be formulated within anholonimic coordinates, here defined by the Frenets triads of the structural lines, being generally in motion. The geometrical terms for the current of the dislocation of the line structure, the current of the torsion of the lines (without defects) as well as the current of line disclination are explained.
Impact Parameter Dependence of K‐Shell Vacancy Production in Collisions of 1 MeV/a. m. u. Cu lons with Cu, Ge and Ag Atoms
Authors: Frank W. , Jaracz P. , Kaun K.‐H. , Rüdiger J. , Stachura Z.
Published: May 2007

The mechanism of K‐shell vacancy production is studied in an X‐ray‐scattered ion coincidence experiment with 63 MeV 63Cu4+ ions colliding with natural Cu, Ge and Ag targets. The impact parameter dependent K‐shell vacancy production probability measured in the experiment is analysed in terms of the rotational coupling and the statistical models. The K‐shell vacancy sharing ratio between the collision partners is compared with the predictions to the Demkov model.
Aspects of an Unitary Classical Molecular Theory of the Crystalline and the Fluid State at Thermal Equilibrium
Authors: Klupsch Th.
Published: May 2007

It is shown that, in spite of the existence of localized particles in crystals, an unitary partition function and grand partition function, resp., exists for the fluid and the crystalline state if an auxiliary external potential is introduced and, following BOGOLYUBOV'S idea, its zero limit is taken after carrying out the thermodynamic limit. Therefore, an unitary description of both the states (including the phase boundary between them) based on molecular distribution functions is possible. A new class of exact correlation functions characterizing localized particles is considered. The excess part of the free energy functional which results from a functional integration of the direct correlation function shows finite self‐interaction contributions of localized particles which must be removed by an additional renormalization procedure.
On Treder‐Type Tetrad Theories of Gravitation II. Treder's Tetrad Theories in Linear Approximation
Authors: Bleyer U.
Published: May 2007

We consider some properties of TREDER'S tetrad theories, derived in I, using the field equations proposed by KASPER and LIEBSCHER. The linearized theory is considered, because the field energy becomes positive, if the energy of the weak field is a positive one. Using the dynamical equations, the field equations lead for the symmetric part of the field to the gauge invariant field equations in Hilbert gauge and to corresponding equations for the antisymmetric part. This means that in this approximation the dynamical equations replace the gauge invariance and the tetrad field corresponds to a mixture of tensor and scalar gravitons. We discuss possible experiments for showing the existence of scalar gravitons and limiting the free parameter of the theory.
A Simple Model for Describing Non‐Markovian Vibrational Relaxation
Authors: Süsse K. ‐E. , Vogel W. , Welsch D. ‐G.
Published: May 2007

Assuming bilinear coupling between the dynamical and dissipative system an analytically solvable model for calculation of non‐Markovian relaxation behaviour is proposed.
Optimum Conditions for Elliptical Focusing in Singly Resonant Optical Parametric Oscillators with Hemispherical Resonator
Authors: Fischer R. , Nickles P. V. , Chu Tran Bá , Wieczorek L. ‐W.
Published: May 2007

Optimum conditions for elliptical focusing are derived for singly resonant optical parametric oscillators with hemispherical resonator in dependence on double refraction. By elliptical focusing it is possible to focus more tightly in the non‐walk‐off plane. In a LiNbO3 oscillator pumped with 1,06 μm radiation the threshold pump power can be lowered about a factor 6 by elliptical focusing in comparison with circular focusing.
Das Spinproblem in der klassischen Elektrodynamik
Authors: Ternov I. M. , Bordowitsyn W. A.
Published: May 2007

Es werden die Hauptthesen der klassischen relativistischen Theorie des Spins eines punktförmigen Teilchens formuliert. Ausgehend davon wird die Ableitung der Spinbewegungsgleichungen angegeben und gezeigt, daß bei Berücksichtigung des anomalen magnetischen Momentes des Teilchens die BARGMANN‐MICHEL‐TELEGDI‐Gleichungen sowie die Gleichungen von Good, NYBORG und anderen als Spezialfälle in den klassischen Spin‐Gleichungen von FRENKEL enthalten sind.
Influence of Magnetic Susceptibility on Position and Line‐width of Proton Magnetic Resonance Lines in Powder Samples of Transition Metal Hydrides
Authors: Göring R. , Schnabel B.
Published: May 2007

The basic theoretical ideas about the influence of the magnetic susceptibility of the sample material on the nuclear magnetic resonance line position and width of powder samples are discussed. Three different effects may occur the respective influence of which could be derived from multiple‐pulse line‐narrowing experiments with and without rapid magic‐angle sample spinning using powder samples mixed from polymer and metal powders. Measures to avoid the influence of the susceptibility effects are proposed.
Comparison between Two Approaches to the Study of the Collision Dominated Electron Relaxation in Weakly Ionized Plasmas under the Action of an Electric Field
Authors: Braglia G. L. , Wilhelm J. , Winkler R.
Published: May 2007

Recently it has been shown that in steady‐state situations under certain parameter conditions the conventional Boltzmann equation solution approach using the well known two‐term Legendre polynomial expansion fails to provide a sufficiently accurate description of the energy distribution and resulting macroscopic quantities of the electrons. Over the past few years, detailed studies of the temporal relaxation of electrons in a homogeneous, collision dominated, weakly ionized plasma have been performed using always the same approximation technique. Thus it is of particular interest to check the applicability of such a two‐term approximation to temporal relaxation processes by an independent approach without such limitation. An important improvement of Monte Carlo methods recently obtained allows to determine the energy distribution function far into the high energy range for steady‐state situations; further simulations of the non‐stationary evolution are now possible with high accuracy for a limited time period. Using these Monte Carlo techniques and the conventional approach we compared the energy distribution functions and some macroscopic quantities, in particular the excitation collision frequencies, in the inert gas plasmas of Ne and Ar for three selected cases of temporal relaxation. The results obtained with these two methods for different initial situations and for both inert gas plasmas with their very different atomic data show a very good agreement and thus confirm the validity of the two‐term approximation over the whole relaxation process for the considered cases.
On Gauge Invariant Theories of Gravitation
Authors: Bleyer U.
Published: May 2007

Theories of gravitation are called gauge invariant if the invariance of the gravitational field lagrangian with respect to gauge transformations of the gravitational field variables is independend of the invariance of this lagrangian with respect to the Einstein group of general coordinate transformations. They are bimetric theories because the coordinate covariance is ensured by constructing scalar densities relative to a globally flat background metric. Such a theory is represented by the PAUL‐FIERZ equations for massless spin 2 particles. But this theory is inconsistent if nongravitational matter is enclosed as a source. All attempts to overcome this inconsistancy preserving gauge invariance lead to Einstein's GRT. We review this problem and compare the situation with a theory proposed by LOGUNOV showing that he overcomes the inconsistency of linear Einstein's equations by replacing the field variables by a gauge invariant combination of new ones, which turns out to be the first order form of v. FREUD'S superpotential.
Diagram Expansions in Nonequilibrium Statistical Mechanics Classical Limit Considerations
Authors: Der R. , Fritzsche S. , Haberlandt R.
Published: May 2007

A diagram expansion is proposed for calculating traces of the kind Tr{Ae−itLB} which are of interest for calculating time correlation functions and expectation values in nonequilibrium statistical mechanics. Arbitrary initial conditions are considered. In the classical limit the diagram expansion of FUJITA is obtained. A systematic method for obtaining quantum corrections including exchange and symmetry effects is proposed.
Field Theoretic Renormalization Group and the Scaling Behaviour in Polymer Solutions
Authors: Stepanow S.
Published: May 2007

Quantum field theoretic regularization methods are used to regularize the set of end‐to‐end chain correlation functions. The renormalization group invariance of the polymer theory allows to calculate the parameters g and S which in the regularized theory take on the role of z and Nl2 of the two parameter theory accordingly. The second virial coefficient A2 and the mean‐square end‐to‐end polymer distance R2 of a polymer solution are represented in powers of g. g and S are evaluated up to order ϵ2 (ϵ = 4 ‐ d, where d is the space dimension). A2 and R2 are calculated up to order g2 and g, respectively, and compared with results obtained by ELDERFIELD and des CLOIZEAUX.
Über analytische Eigenschaften der Einteilchengreenfunktionen in einem Zwei‐Band‐Modell
Authors: Schumann R. , Elk K.
Published: May 2007

Im Zusammenhang mit Integralen über Lorentz‐verteilte stochastische Parameter in der Ein‐Zentren‐Streumatrix werden deren analytische Eigenschaften diskutiert. Dazu werden optische Theoreme für die Greenschen Einteilchenfunktionen in einem Zwei‐Band‐Modell hergeleitet.
Über die dynamische Gleichung in der Hermiteschen Relativitätstheorie
Authors: Treder H.‐J.
Published: May 2007

Bemerkungen zur physikalischen Bedeutung der Bianchi‐Identität in der Einstein‐Strausschen Hermiteschen Relativitätstheorie.
Ein Verfahren zur Messung der Rauhigkeitsautokorrelationsfunktion von polierten Glasoberflächen mittels Streubildscherung
Authors: Walther H. G.
Published: May 2007

Es wird ein Verfahren zur Messung der Rauhigkeitsautokorrelationsfunktion von polierten Glasoberflächen vorgestellt, bei dem die Interferenz von zwei lateral gegeneinander verschobenen Streulichtabbildungen ausgewertet wird. Dieses Verfahren wird für verschiedene Polituren von BK 7‐ und BaK 4‐Proben getestet. Der auftretende systematische Meßfehler infolge Bildverwaschung wird abgeschätzt.
Untersuchung der Lichtstreuung von transparenten Einfachschichten auf Glassubstraten
Authors: Walther H.‐G. , Schirmer G.
Published: May 2007

In der vorliegenden Arbeit werden der Einfluß der statistischen Grenzflächenrauhigkeit sowie der Schichtdicke auf das Streulichtverhalten von dielektrischen Einfachschichten auf transparenten Substraten theoretisch und experimentell untersucht. In Modellrechnungen auf der Grundlage der Vektorstreutheorie von Elson wird besonders die Bedeutung der Korrelationseigenschaften der Mikrorauhigkeit analysiert. Die an gesputterten TiO2‐Schichten durchgeführten Messungen weisen auf dominierende Grenzflächenstreuung hin und zeigen in Übereinstimmung mit der Theorie eine ausgeprägte schichtdickenabhängige Streulichtinterferenz.
A Closed Friedmann Universe with a Scalar Field as Source
Authors: Gottlöber S.
Published: May 2007

The evolution is examined of a closed Friedmann universe, the source of which is a classical massive scalar field. Supposing a minimal value a0 the initial values are chosen in such a way that the solutions are time symmetric. The scale factor passes a maximal value and then decreases to zero (singularity). For special initial values a phase with exponential increasing scale factor exists.