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This work presents an analytical approach for studying the cosmological 21cm background signal from the Dark Ages (DA) and subsequent Epoch of Reionization (EoR). We simulate differential observations of a galaxy cluster to demonstrate how these epochs can be studied with a specific form of the Sunyaev-Zel’dovich Effect called the SZE-21cm. This work produces simulated maps of the SZE-21cm and shows that the SZE-21cm can be extracted from future observations with low-frequency radio interferometers such as the Hydrogen Epoch of Reionization Array (HERA) and the Square Kilometre Array (SKA). In order to simulate near realistic scenarios, we look into cosmic variance noise, incorporate and take into account the effects of foregrounds, thermal noise, and angular resolution for our simulated observations. We further extend this exploration by averaging over a sample of galaxy clusters to mitigate the effects of cosmic variance and instrumental noise. The impact of point source contamination is also studied. Lastly, we apply this technique to the results of the EDGES collaboration, which in 2018 reported an absorption feature of the global 21cm background signal centred at 78 MHz. The challenges to be addressed in order to achieve the objectives of this work include errors that arise due to cosmic variation, instrumental noise and point source contamination. Our approach demonstrates the potential of the SZE-21cm as an indirect probe for the DA and EoR, and we conclude that the spectral features of the SZE-21cm from our simulated observations yield results that are close to prior theoretical predictions and that the SZE-21cm can be used to test the validity of the EDGES detection. [ABSTRACT FROM AUTHOR]

Background: The profession of the anesthetist in Germany includes the disciplines anesthesia, intensive care, emergency and pain medicine. Despite the versatility and competence of the profession, patients do not appear to have recognized anesthesiology as a medical discipline or anesthetists as medical doctors.Aim: This study was conducted with the aim of estimating how previous experience and information gathered before contact with the anesthetist for premedication have influenced and changed the perception of patients with regards to the professional fields and the characteristics of anesthetists.Material and Methods: A total of 3,950 patients from 3 German hospitals were asked to answer a questionnaire handed out by the assistance nurse in the premedication area prior to the medical consultation with the duty anesthetist. The questions involved the patient perception of the discipline, the characteristics of anesthetists and also evaluated the patient previous experience and provision of information. According to the answers 1,753 patients were considered eligible for the study and were categorized into subgroups I-IV (group I interested and experienced with operations, group II interested but inexperienced, group III uninterested but experienced and group IV neither interested nor experienced) for statistical analysis.Results: Of the respondents 56.2 % had obtained previous information from a general practitioner followed by acquaintances (21.4 %) and the internet (19.9 %), which significantly differed with age. Interested and experienced patients showed the best perception of the profession. Often, the knowledge of interested and uninterested persons did not significantly differ. Interested patients and those with experience of anesthesiology had the best knowledge of anesthesiology. Performing anesthesia was most often identified by all groups (50.9-95.3 %) as a function of anesthetists while the other professional fields were recognized correctly by only 5.8-26.6 %. Depending on the group 41.0-84.4 % regarded anesthetists as medical doctors. Only 15.0-78.3 % of other attributes were associated with anesthetists.Conclusion: Unfortunately, the perception of patients on the versatility and characteristics of anesthetists are poorly developed. However, the knowledge differs significantly depending on previous experience and gathered information. Interestingly patients with previous experience mostly showed better knowledge compared to interested patients. Results suggest that personal interaction, patient-physician communication in general and improved collaboration between general practitioners and anesthetists are the key elements for better patient knowledge, which could lead to increased patient satisfaction. [ABSTRACT FROM AUTHOR]

Silver-tin alloy coatings are electrodeposited from a newly developed EDTA containing cyanide-pyrophosphate electrolyte and some properties of the obtained coatings, such as microhardness, internal stress, abrasion resistance, plug-in forces and electrical contact resistance depending upon the applied current density or the tin content of the alloy, respectively, are investigated. The co-deposition of tin leads to the change of the tensile stress of pure silver coatings to compressive stress in the formed solid solution of the alloy and to almost stress free coatings at high current densities. The microhardness runs over a maximum at current densities, where the silver lattice is saturated with tin and the deposition of phase heterogeneous coatings starts. The abrasion resistance diminishes at increased tin content, and the changes of the electrical contact resistance are in the opposite direction. The measured plug-in forces show the lubricating properties of the alloy coatings. [ABSTRACT FROM AUTHOR]

The low efficiency of conventional therapies in achieving long-term survival of lung cancer patients calls for development of novel options. Aerosol gene delivery may provide the alternative for safe and effective treatment for lung cancer. Therefore, current study was performed to elucidate the potential effects of C-terminal modulator protein (CTMP) via aerosol on lung tumorigenesis. Lentiviral vector-CTMP was delivered into K-ras null lung cancer mice through the nose-only inhalation system for 30 min. After 48 h, the potential effects of CTMP on Akt1-related signals and cell cycle regulation in the lungs were evaluated by western blot, immunohistochemistry and zymography. Lentivirus-based CTMP delivery inhibited the Akt1 activity through selective suppression of Akt1 phosphorylation at Ser473. Aerosol delivery of CTMP inhibited proteins important for Akt1 signals, cell cycle and tumor metastasis in lungs of K-ras null mice. Together, our results suggest that lentivirus-mediated aerosol delivery of CTMP may be compatible with noninvasive in vivo gene therapy. Our results emphasize the importance of noninvasive-targeted delivery of CTMP for lung cancer therapy in the future. While the studies are conducted in mice, it is envisioned that noninvasive targeting the specific genes responsible for cancer progression is an attractive strategy for effective anticancer therapeutics.Gene Therapy (2007) 14, 1721–1730; doi:10.1038/sj.gt.3303042; published online 25 October 2007 [ABSTRACT FROM AUTHOR]

Objective: Resistant hypertension is an important clinical problem that is poorly studied and not well managed. The objective of this study was to identify factors associated with successful treatment of resistant hypertension in a specialty clinic. Methods: This was a retrospective observational study examining the medical records of patients seen at a specialty hypertension clinic at the University of Rochester, Rochester, New York, USA, in the year 2005. The records of 68 patients were reviewed. Those presenting with resistant hypertension (defined as BP ≥140/90mm Hg and receiving at least three antihypertensive medications, including a diuretic) were identified. Change in medication type and dosage, BP reduction, and percentage of patients at Joint National Committee (JNC)-7 goal were noted. Results: Twenty-eight patients were included in the analysis. Mean age was 62.5 ± 11.6 years, 54% were women, and mean presenting BP was 175.4 ± 23.5/87.5 ± 14.6mm Hg. After an average of 6.2 ± 3.2 visits over a mean of 13.9 ± 13.5 months, mean BP was reduced to 145.3 ± 27.7/73.9 ± 13.6mm Hg (paired t-test: p = 0.001 SBP, p = 0.0001 DBP), and 44.8% of the patients were at their JNC-7 goal. Change in the mean number of antihypertensive medications was not significantly different between the initial and final clinic visits (4.1 ± 1.2 vs 4.2 ± 1.0; p = 0.627). Combination pill use increased from four patients (14%) at initial visit to 19 (68%) at final visit. Numbers of patients treated with diuretics, β-adrenoceptor antagonists, calcium channel antagonists (CCB), and minoxidil increased at the final clinic visit. Significant dose-related changes included the up-titration of CCBs to high doses, and the initiation of moderate doses of thiazide diuretics; mainly chlorthalidone (67% final visit vs 0% at initial visit). Conclusions: Patients referred to a specialty clinic for the control of resistant hypertension achieved significant reductions in BP with frequent visits, combination pills, and greater use and higher doses of CCBs and thiazide diuretics. [ABSTRACT FROM AUTHOR]

Lung cancer has emerged as a leading cause of cancer death in the world; however, most of the current conventional therapies are not sufficiently effective in altering the progression of disease. Therefore, development of novel treatment approaches is needed. Although several genes and methods have been used for cancer gene therapy, a number of problems such as specificity, efficacy and toxicity reduce their application. This has led to re-emergence of aerosol gene delivery as a noninvasive method for lung cancer treatment. In this study, nano-sized glucosylated polyethyleneimine (GPEI) was used as a gene delivery carrier to investigate the effects of Akt wild type (WT) and kinase deficient (KD) on Akt-related signaling pathways and protein translation in the lungs of CMV- LucR-cMyc-IRES-LucF dual reporter mice. These mice are a powerful tool for the discrimination between cap-dependent/-independent protein translation. Aerosols containing self-assembled nano-sized GPEI/Akt WT or GPEI/Akt KD were delivered into the lungs of reporter mice through nose-only-inhalation-chamber with the aid of nebulizer. Aerosol delivery of Akt WT caused the increase of protein expression levels of Akt-related signals, whereas aerosol delivery of Akt KD did not. Furthermore, dual luciferase activity assay showed that aerosol delivery of Akt WT enhanced cap-dependent protein translation, whereas a reduction in cap-dependent protein translation by Akt KD was observed. Our results clearly showed that targeting Akt may be a good strategy for prevention as well as treatment of lung cancer. These studies suggest that our aerosol delivery is compatible for in vivo gene delivery which could be used as a noninvasive gene therapy in the future.Gene Therapy (2007) 14, 451–458. doi:10.1038/sj.gt.3302879; published online 19 October 2006 [ABSTRACT FROM AUTHOR]

In vitro and in vivo studies have demonstrated that apart from its hemodynamic action dopamine can modulate immune responses. Dopamine reduces the synthesis of proinflammatory and induces the synthesis of anti-inflammatory mediators. Dopamine inhibits neurohormone synthesis, lymphocyte proliferation and platelet aggregation. It reduces the phagocytic activity of neutrophils and induces apoptosis. Particularly with regard to sepsis, where high serum dopamine levels are reached by enhanced endogenous production, exogenous application and impaired clearance, this immunomodulation may have a clinical impact. This review summarizes dopamine-mediated immunomodulating effects to advance the knowledge regarding dopamine as an immune regulator under septic conditions. [ABSTRACT FROM AUTHOR]

Summary. Homocysteine levels and the frequency of heterozygous methylenetetrahydrofolate reductase (MTHFR) C677T mutation are increased in open-angle glaucoma. Since homocysteine can induce vascular injury, alterations in extracellular matrix remodelling, and neuronal cell death, these findings may have important implications for understanding glaucomatous optic neuropathy. [ABSTRACT FROM AUTHOR]

Glomerular filtration rate (iothalamate clearance) was measured serially for 48 months in 26 Pima Indians with impaired glucose tolerance and 27 with normal glucose tolerance. At baseline, the mean glomerular filtration rate (SEM) was 133 ± 8 ml/min in subjects with impaired glucose tolerance and 123 ± 5 ml/min in those with normal glucose tolerance ( p = 0.12). In the 12 subjects with impaired glucose tolerance who progressed to Type II (non-insulin-dependent) diabetes during follow-up, mean glomerular filtration rate increased by 30 % ( p = 0.011). Among the remaining 14 subjects with impaired glucose tolerance, 12 reverted to normoglycaemia. The glomerular filtration rate both at baseline and after 48 months in this subgroup exceeded the values of subjects with normal glucose tolerance by 20 % ( p = 0.008) and 14 % ( p = 0.013), respectively. A pronounced rise in the glomerular filtration rate occurs at the onset of Type II diabetes but a trend to hyperfiltration is also present in those with impaired glucose tolerance. [Diabetologia (1999) 42: 90–93] [ABSTRACT FROM AUTHOR]

Deuteron disintegration by electrons is calculated in a covariant model for the quasifree region, where final-state interaction and two-body currents can be negiected, and is compared to a phenomenological approach in which one adds to the nonrelativistic one-body current relativistic contributions of lowest order and the kinematic wave-function boost. It is shown that a p/M-reduction of the relativistic theory contains the expressions of the phenomenological approach. The inclusion of relativistic contributions leads to a less frame-dependent description and the deviation from the covariant theory becomes small at low and medium energy and momentum transfers. Furthermore, the dependence of the nonrelativistic results on the current parametrization, i.e., Dirac-Pauli versus Sachs, is largely eliminated by inclusion of lowest-order relativistic contributions. Results are presented for form factors and structure functions and compared with experimental data for the inclusive reaction. [ABSTRACT FROM AUTHOR]

The influence of relativistic effects in deuteron electrodisintegration, in particular their manifestation in spin observables, is discussed. We have used a simple phenomenological approach by adding the lowest-order relativistic corrections to the nonrelativistic one-body current and including the kinematic wave-function boost. Furthermore, final-state interaction, meson-exchange currents and isobar configurations are included in order to study kinematic regions off the quasi-free case. Sizeable relativistic effects in many observables are found even at low energies. [ABSTRACT FROM AUTHOR]

The role of relativistic effects in deuteron break-up by electrons is investigated for quasi-free kinematics by including the lowest-order relativistic corrections beyond the nonrelativistic limit to electromagnetic operators and by wave-function boost. In particular, the dependence of form factors and structure functions on the frame in which they are calculated is studied. It is found that the inclusion of these corrections leads to observables that are less frame-dependent than for a pure nonrelativistic description. The boost contributions show a decisive influence even though they are small in absolute size. Furthermore, the dependence on the parametrization of the nucleon current in terms of Dirac-Pauli or Sachs form factors is considerably reduced by inclusion of relativistic contributions. [ABSTRACT FROM AUTHOR]

The vegetation of seasonally flooded savannas iin the tropical lowland of the Departamento La Paz, northern Bolivia, was studied. A first collection of vascular plants in this area includes about 600 species, at least three of which are new to the Bolivian flora and four are new to science. The eight major vegetation types distinguished within the savannas are dry bunchgrass savanna ('altura'), seasonally flooded bunch-grass community ('sartenejal'), palm swamp ('palmar'), two types of river floodplains ('bajíos'), a tall shrub community ('chaparral'), the vegetation of termite mounds, and gallery forest. The study area is among the least known in Bolivia. There is a strong need for further studies of these savannas. [ABSTRACT FROM AUTHOR]

Purpose. Oral bioavailability for antisense oligonucleotides has recently been reported but the mechanistic details are not known. The proposed oral delivery of nucleic acids will, therefore, require an understanding of the membrane binding interactions, cell uptake and transport of oligonucleotides across the human gastro-intestinal epithelium. In this initial study, we report on the cell-surface interactions of oligonucleotides with human intestinal cells. Methods. We have used the Caco-2 cell line as an in vitro model of the human intestinal epithelium to investigate the membrane binding interactions of 20-mer phosphodiester (PO) and phosphorothioate (PS) oligonucleotides. Results. The cellular association of both an internally [H]-labelled and a 5′end [P]-labelled PS oligonucleotide (3.0% at 0.4 µM extracellular concentration) was similar and was an order of magnitude greater than that of the 5′end [P]-labelled PO oligonucleotide (0.2%) after 15 minutes incubation in these intestinal cells. The cellular association of PS was highly saturable with association being reduced to 0.9% at 5 µM whereas that of PO was less susceptible to competition (0.2% at 5 µM, 0.1% at 200 µM). Differential temperature-dependence was demonstrated; PS interactions were temperature-independent whereas the cellular association of PO decreased by 75% from 37°C to 17°C. Cell association of oligonucleotides was length and pH-dependent. A decrease in pH from 7.2 to 5.0 resulted in a 2- to 3-fold increase in cell-association for both backbone types. This enhanced association was not due to changes in lipophilicity as the octanol:aqueous buffer distribution coefficients remained constant over this pH range. The ability of NaCl washes to remove surface-bound PS oligonucleotides in a concentration-dependent manner suggests their binding may involve ionic interactions at the cell surface. Cell-surface washing with the proteolytic enzyme, Pronase, removed approximately 50% of the cell-associated oligonucleotide for both backbone types. Conclusions. Binding to surface proteins seems a major pathway for binding and internalization for both oligonucleotide chemistries and appear consistent with receptor (binding protein)-mediated endocytosis. Whether this binding protein-mediated entry of oligonucleotides can result in efficient transepithelial transport, however, requires further study. [ABSTRACT FROM AUTHOR]

Introduction: Phototoxicity of intra-tumoral injected methylene blue (MB+) was studied in 48 experimental colonic tumours in comparison with photosan-3, Zn-phthalocyanine and tetrasulphanated ClAl-phthalocyanine. Methods: In mice, xenotransplanted subcutaneous tumours about 1 cm in diameter were treated photodynamically twice, with different sensitisers. The irradiation was performed at the sensitiser-specific wavelength, and a densitiy of 100 mW/cm2 and a dose of 100 J/cm2. Results: Light alone without sensitiser did not induce any effect in mice tumours. Surprisingly, Al-phthalocyanine could only be used for intratumoral injections because of toxic effects after intravenous applications in nude mice. Using MB+ (1%), 75% of the tumours were destroyed by a single photodynamic treatment (PDT). In addition, toxicity of MB+ was most intense when compared with Zn-phthalocyanine and photosan-3. However, after the second PDT, there was no statistically significant difference among these sensitisers. Dark toxicity of MB+ (1%) could be well demonstrated by sufficient sensitiser incorporation without irradiation, which led to a stationary tumour volume up to 3 weeks after injection. Conclusion: Intra-tumoral MB+ PDT is a potential treatment for inducing necrosis in vivo. With regard to tumour tissue, the selectivity of MB+ is high and depends on a precise local injection of the dye. [ABSTRACT FROM AUTHOR]

We recorded the prevalence of respiratory symptoms as well as smoking habits, occupational and other environmental exposures, and lung function (maximum expiratory flow-volume [MEFV]) curves in 7,984 community residents (age 7 + years) and in 691 cotton textile workers (age 45 + years). Apart from a slight but significant excess among urban nonsmoking adults of usual cough, usual phlegm and dyspnea, but not of chronic bronchitis, there were no significant differences in respiratory health between residents of urban Ansonia, Connecticut, rural Lebanon, Connecticut, and rural Winnsboro, South Carolina. Lung function values, including flows on MEFV curves, did not differ significantly in nonsmokers, nor in smokers, in the three communities, after sex, race, age, height, and weight were taken into account. Smoking of cigarettes but not of pipes or cigars was associated with significant loss of lung function. Cotton textile workers had a significant excess of both symptoms and lung function loss; the effects of smoking and of cotton dust exposure were additive. Among the community residents, a history of asthma was most common in the least polluted rural town, Winnsboro. From our own data and from comparisons between our data and those of others in either more polluted or less polluted areas, we have concluded that control of air pollution outdoors is unlikely to decrease the health impact of chronic lung diseases. Prevention of cigarette smoking and of occupational exposures, on the other hand, deserves high priority as a public health problem. In particular, adequate control of exposures to dust and fumes in industry could completely prevent disabling chronic lung disease among groups of workers now at high risk, such as cotton textile workers. [ABSTRACT FROM AUTHOR]

We recorded respiratory symptoms and maximum expiratory flow-volume curves in 645 white male and female cotton textile workers, aged 45 years and older, with an average of 35 years employment in carding, spinning, yarn preparing, weaving and other jobs in cotton textile mills. We included retired as well as active workers, to avoid the biases inherent in studies of active workers only. We compared the data on the textile workers with those of 662 female and 498 male white residents of three communities without cotton textile mills (controls), considering sex, age and smoking habits. Textile workers of both sexes, irrespective of age, had significant excesses of chronic cough, wheezing, dyspnea and other symptoms, in comparison with the controls. Work in textile mills was the prime variable affecting symptom prevalence, with smoking as an additional significant variable for all symptoms except dyspnea. The lungfunction data confirmed that textile workers were at much greater risk of chronic lung disease, with loss of function, than the controls, in all smoking categories. There was evidence that chronic lung disease often led to premature retirement among the male textile workers. The excess risk of lung-function loss occurred among workers in yarn preparing and weaving, as well as in carding and spinning, but not among workers employed in clothrooms and in other dust-free jobs. At least 35,000 men and women in the U.S. may suffer from disabling lung-function loss, owing to chronic lung disease, as a result of their work in cotton textile mills. Adequate programs of prevention and control of chronic lung disease, a late stage of byssinosis, as well as of the earlier acute manifestations of byssinosis, are urgently needed. [ABSTRACT FROM AUTHOR]

The average lifetime of b-flavoured baryons measured with the OPAL detector is updated to include data collected between 1990 and 1994 at LEP. Bottom-flavoured baryons that decay semileptonically and produce a Λ baryon are identified through the correlation of the baryon number of the Λ and the electric charge of the lepton. To measure the lifetime, the decay point of the b baryon is estimated by the Λ-lepton vertex, and the observed distribution of decay lengths is fitted simultaneously in 874 right-sign and 384 wrong-sign combinations. In a separate method, the impact parameter distribution of the leptons is fitted in a subset of these data. When the two results are combined, taking correlations into account, the average b-baryon lifetime is found to be τ=1.16±0.11(stat.)±0.06(syst.) ps. Using the same data, the product branching ratio is measured to be $$\begin{gathered} \hfill f(b \to \Lambda _b ) \cdot BR(\Lambda _b \to \Lambda \ell ^ - \bar vX) = (2.91 \pm 0.23(stat.) \\ \hfill \pm 0.25(stat.)) \cdot 10^{ - 3} \\ \end{gathered} $$ , where the symbol f(b→ Λ ) is the fraction of b quarks from Z decays forming b baryons, Λ represents all b-flavoured baryons and ℓ is either an electron or a muon. [ABSTRACT FROM AUTHOR]

Symmetric three-jet events are selected from hadronic Z decays such that the two lower energy jets are each produced at an angle of about 150° with respect to the highest energy jet. In some cases, a displaced secondary vertex is reconstructed in one of the two lower energy jets, which permits the other lower energy jet to be identified as a gluon jet through anti-tagging. In other cases, the highest energy jet is tagged as a b jet or as a light quark (uds) jet using secondary vertex or track impact parameter and momentum information. Comparing the two lower energy jets of the events with a tag in the highest energy jet to the anti-tagged gluon jets yields a direct comparison of b, uds and gluon jets, which are produced with the same energy of about 24 GeV and under the same conditions. We observe b jets and gluon jets to have similar properties as measured by the angular distribution of particle energy around the jet directions and by the fragmentation functions. In contrast, gluon jets are found to be significantly broader and to have a markedly softer fragmentation function than uds jets. For the k jet finder with y =0.02, we find $$\begin{gathered} \frac{{\left\langle {n^{ch.} } \right\rangle gluon}}{{\left\langle {n^{ch.} } \right\rangle b quark}} = 1.089 \pm 0.024(stat.) \pm 0.024(syst.) \hfill \\ \frac{{\left\langle {n^{ch.} } \right\rangle gluon}}{{\left\langle {n^{ch.} } \right\rangle uds quark}} = 1.390 \pm 0.038(stat.) \pm 0.032(syst.) \hfill \\ \end{gathered} $$ as the ratios of the mean charged particle multiplicity in the gluon jets compared to the b and uds jets. Results are also reported using the cone jet finder. [ABSTRACT FROM AUTHOR]

The dependence of event shape cross sections on the QCD structure constants C, C and T is studied using data from the OPAL detector at LEP. The observables Thrust, Heavy Jet Mass, Total and Wide Jet Broadening are used. They allow the use of O(α), resummed NLLA, and combined O(α) plus resummed NLLA QCD calculations so that a comparison between the different approaches can be performed. The measured values of the structure constants are found to be consistent with standard QCD based on SU(3) and five active quark flavours. A measurement of the strong coupling constant using NLLA QCD calculations alone results in $$\alpha _s (M_{Z^0 } ) = 0.113_{ - 0.008}^{ + 0.009}$$ , which complements our previous determinations. [ABSTRACT FROM AUTHOR]

The string effect in QCD is investigated using data from the OPAL detector at LEP. By comparing the charged particle flow in three-jet multihadronic events with that in events with two jets and a hard isolated photon, the sensitivity to particular models is reduced. A comparison with various Monte Carlo models is presented. The difference in particle flows in the interquark region is found to be well reproduced by a leading order calculation of soft gluon emission, in the spirit of the Local Parton Hadron Duality hypothesis. [ABSTRACT FROM AUTHOR]

The branching ratios of the τ→ h h h v and τ→ h h h≥1π v decays, where h is either a charged π or K meson, are measured using a data sample of 87861 ττ pairs collected with the OPAL detector at LEP. The two branching ratios are extracted simultaneously from a sample of three charged particle decays and found to be: where the first error is statistical and the second systematic. The branching ratio of the τ lepton into three charged particles is measured to be: [ABSTRACT FROM AUTHOR]

Three jet events are selected from hadronic Z decays with a symmetry such that the two lower energy jets are produced with the same energy and in the same jet environment. In some of the events, a displaced secondary vertex is reconstructed in one of the two lower energy jets, which permits the other lower energy jet to be identified as a gluon jet, with an estimated purity of about 93%. Comparing these gluon jets to the inclusive sample of lower energy jets from the symmetric data set yields direct, model independent measurements of quark and gluon jet properties, which have essentially no bias except from the jet definition. Results are reported using both the k and cone jet definitions. For the k algorithm, we find for the ratio of the mean charged particle multiplicity of gluon to quark jets, while for the cone algorithm, we find using a cone size of 30°. We also report measurements of the angular distributions of particle energy and multiplicity around the jet directions, and of the fragmentation functions of the jets. Gluon jets are found to be substantially broader and to have a markedly softer fragmentation function than quark jets, in agreement with our earlier observations. [ABSTRACT FROM AUTHOR]

The fragmentation function for the process ee→ h+X, where h represents a hadron, may be decomposed into transverse, longitudinal and asymmetric contributions by analysis of the distribution of polar production angles. A number of new tests of QCD have been proposed using these fragmentation functions, but so far no data have been published on the separate components. We have performed such a separation using data on charged particles from hadronic Z decays at Opal, and have compared the results with the predictions of QCD. By integrating the fragmentation functions, we determine the average charged particle multiplicity to be $$\overline {n_{ch} } = 21.05 \pm 0.20$$ . The longitudinal to total cross-section ratio is determined to be σ/σ=0.057±0.005. From the longitudinal fragmentation function we are able to extract the gluon fragmentation function. The connection between the asymmetry fragmentation function and electroweak asymmetrics is discussed. [ABSTRACT FROM AUTHOR]

Measurements have been made in the OPAL experiment at LEP of the inclusive production of strange vector φ(1020) and K(892) mesons, and the tensor meson K(1430). The overall production rates per hadronic Z decay have been determined to be 0.100±0.004±0.007 φ(1020) mesons, 0.74±0.03±0.03 K(892) mesons and (for x<0.3) 0.19±0.04±0.06 K(1430) mesons. The measurements for the vector states update previously published results based on lower statistics, while the K(1430) rate represents the first direct measurement of a strange tensor state in Z decay. For the vector states, both the overall production rates and normalised differential cross sections, with respect to the scaled energy variable x, have been compared to JETSET and HERWIG predictions. The peak positions in the ζ=ln(1/ x) distributions have been measured and compared to measurements of other hadron states. [ABSTRACT FROM AUTHOR]

We have searched for lepton flavour violating Z→eμ, Z→eτ and Z→μτ decays in a sample of 4.0×10 visible Z decays collected with the OPAL detector at LEP during 1991 to 1994. No candidates are found for Z→eμ. The samples of selected Z→eτ and Z→μτ candidates are consistent with the expected background. The following limits are set at 95% confidence level: [ABSTRACT FROM AUTHOR]

The production of neutral kaons in ee annihilation at centre-of-mass energies in the region of the Z mass and their Bose-Einstein correlations are investigated with the OPAL detector at LEP. A total of about 1.26×10 Z hadronic decay events are used in the analysis. The production rate of K mesons is found to be 1.99±0.01±0.04 per hadronic event, where the first error is statistical and the second systematic. Both the rate and the differential cross section for K production are compared to the predictions of Monte Carlo generators. This comparison indicates that the fragmentation is too soft in both Jetset and Herwig. Bose-Einstein correlations in KK pairs are measured through the quantity Q, the four momentum difference of the pair. A threshold enhancement is observed in KK pairs originating from a mixed sample of $$K^0 \bar K^0$$ and KK ( $$\bar K^0 \bar K^0$$ ) pairs. For the strength of the effect and for the radius of the emitting source we find values of λ=1.14±0.23±0.32 and R=(0.76±0.10±0.11) fm respectively. The first error is statistical and the second systematic. [ABSTRACT FROM AUTHOR]

The forward-backward asymmetry of $$e^ + e^ - \to Z^0 \to b\bar b$$ has been measured using approximately 2.15 million hadronic Z decays collected at the LEP ee collider with the OPAL detector. A lifetime tag technique was used to select an enriched $$b\bar b$$ event sample. The measurement of the $$b\bar b$$ asymmetry was then performed using a jet charge algorithm to determine the direction of the primary quark. Values of: were measured where, in each case, the first error is statistical, the second is systematic and the third term gives the variation due to a change $$\Delta (\Gamma _{b\bar b} /\Gamma _{had} )$$ in the value of $$\Gamma _{b\bar b} /\Gamma _{had} = 0.216$$ assumed. The dependence on the assumed charm asymmetry at the same energy is Δ( A)≈+0.07Δ( A). Assuming the Standard Model form for the couplings, these measurements correspond to an effective weak mixing angle of: giving M=196GeV/ c, where the first error is statistical and the second is systematic. The Higgs mass assumed is 300 GeV/ c. A variation in the assumed mass of the Higgs boson between 60 and 1000 GeV/ c corresponds to an uncertainty in sinθ of ±0.00006 and on M ofGeV/ c. [ABSTRACT FROM AUTHOR]

Updated measurements of the B and B meson lifetimes are presented. From a data sample of 1.72 million hadronic Z decays recorded during the period 1991 to 1993, a sample of approximately 1000 semileptonic B meson decays containing a D, D or D has been isolated. From the distribution of decay times in the different samples the lifetimes of the B and B mesons are determined to be 1.53±0.12±0.08 ps and 1.52±0.14±0.09 ps, respectively, where the first error is statistical and the second systematic. The ratio of the B to B lifetimes is measured to be 0.99±0.14, confirming expectations that the lifetimes are similar. [ABSTRACT FROM AUTHOR]

Using the OPAL data accumulated in 1991-1993 amounting to 74 pb of integrated luminosity, corresponding to 1.64×10 selected multi-hadronic events, a search has been performed for charged particles with unusual mass or unusual charge. The mass was determined from a combination of momentum and ionization energy loss measurements. No isolation criteria were applied to the tracks examined, so that both isolated particles and particles produced in jets were valid candidates. For particles with charge Q/e=−1, one candidate with a mass of approximately 4.2 GeV/c was found, which is compatible with the background rate expected according to a Monte Carlo simulation. The implications of this search for the mass limits of a conjectured stable or quasi-stable charged gluino composite $$(\tilde gq\bar q')^ \pm $$ are discussed. Limits are also presented for the production of fractionally-charged particles with Q/e=±2/3 and ±4/3 as well as for particles with Q/e=±2. [ABSTRACT FROM AUTHOR]

We have studied the production of D mesons in a sample of 1.25 million multihadronic decays of the Z, in which 1969 candidates have been identified. We have determined the total multiplicity of charged D mesons in multihadronic Z decays to be [ABSTRACT FROM AUTHOR]

The properties of hadronic Z decays with final state photons, measured with OPAL at LEP, have been compared with predictions from two different matrix element calculations of O(αα). Two calculations, GNJETS and EEPRAD, have been investigated which use different schemes to restrict the phase space around the poles of the cross section. Assuming the E0-JADE jet definition, both calculations describe the data well in large regions of phase space for y values around 0.06. For very large and very small jet-photon masses some deviations from the predictions have been found, indicating the importance of higher order corrections. Significant differences between the calculations are only apparent in the predicted rate of 1-jet plus photon events. The rate is higher in GNJETS which reproduces the data better than EEPRAD. [ABSTRACT FROM AUTHOR]

The decay τ→π v has been studied using data collected with the OPAL detector at LEP during 1992 and 1993. The hadronic structure functions for this decay are measured model independently assuming G-parity invariance and neglecting scalar currents. Simultaneously the parity violating asymmetry parameter is determined to be $$\gamma VA = 1.08 _{ - 0.41 - 0.25}^{ + 0.46 + 0.14} $$ , consistent with the Standard Model prediction of γ VA=1 for left-handed tau neutrinos. Models of Kühn and Santamaria and of Isgur et al. are used to fit distributions of the invariant 3π mass as well as 2π mass projections of the Dalitz plot. The model dependent mass and width of the a resonance are measured to be $$m_{a_1 } = 1.266 \pm 0.014_{ - 0.002}^{ + 0.012} $$ GeV and $$\Gamma _{a_1 } = 0.610 \pm 0.049_{ - 0.019}^{ + 0.053} $$ GeV for the Kühn and Santamaria model and $$m_{a_1 } = 1.202 \pm 0.009_{ - 0.001}^{ + 0.009} $$ GeV and $$\Gamma _{a_1 } = 0.422 \pm 0.023_{ - 0.004}^{ + 0.033} $$ GeV for the Isgur et al. model. The model dependent values obtained for the parity violating asymmetry parameter are γ=0.87±0.27 for the Kühn and Santamaria model and γ=1.10±0.31 for the Isgur et al. model. Within the Isgur et al. model the ratio of the S-and D-wave amplitudes is measured to be D/S=−0.09±0.03±0.01. [ABSTRACT FROM AUTHOR]

The results of a study of charm meson production in semileptonic B hadron decays are presented. Based on a sample of 1.72 million hadronic Z decays the following product branching ratios (averaged over electrons and muons) are obtained: where the first error is statistical and the second systematic. The results of a search for the narrow P-wave charmed mesons, (D), in semileptonic B decays are also reported. Using the decay channels D→Dπ, D→Dπ and D→Dπ we observe a total signal of 44±8 D and 48±10 D events. This is the first evidence for semileptonic B decays to charged P-wave charm states. The observed signals also provide evidence for the production of both pseudovector and tensor P-wave charmed mesons in semileptonic B decay. Together these modes are estimated to make up 34±7% of charmed semileptonic B and B decays. [ABSTRACT FROM AUTHOR]

The leptonic branching ratios of the tau lepton have been determined from data collected by the OPAL detector in 1991 and 1992. From a sample of 27196 ee→ττ candidates we find 7322 $$\tau \to e\nu \bar \nu$$ and 7941 $$\tau \to \mu \nu \bar \nu$$ candidates. Using efficiency and background estimates determined from a study of Monte Carlo events and control samples of data, the branching ratios $$B(\tau \to e\nu \bar \nu )$$ =(18.14±0.20±0.28)% and $$B(\tau \to \mu \nu \bar \nu )$$ =(17.48±0.18±0.23)% have been obtained. These new results have been combined with the published results for the 1990 OPAL data to yield the following branching ratios for data taken between 1990 and 1992: These leptonic branching ratios are used with other properties of the muon and tau-lepton to test the universality of charged current leptonic couplings in these decays. The ratio $$R_\tau = B(\tau \to hadrons + \nu _\tau )/B(\tau \to e\bar \nu _e \nu _\tau )$$ is calculated using our measured values of the leptonic branching fractions of the tau and tau lifetime from which a value of α( Q= M) is extracted. The value of α( Q= M) is obtained by Q evolution and agrees with the value from the Z line shape analysis. [ABSTRACT FROM AUTHOR]

The time dependence of B meson oscillations is studied using hadronic Z decays with identified leptons in both thrust hemispheres. Decay times are reconstructed for each of the semileptonic B decays by forming vertices which include the lepton and by estimating the B meson momentum. The mass difference of the two mass eigenstates in the B system, Δ m, is measured to be $$0.462_{ - 0.053 - 0.035}^{ + 0.040 + 0.052} ps^{ - 1}$$ , where the first error is statistical and the second systematic. For the B system, a lower limit of Δ m>2.2 ps at 95% C.L. is derived. [ABSTRACT FROM AUTHOR]

Evidence is presented for kinematic and charge correlations of B mesons with charged pions and kaons. Using a new technique, a sample of over 80 000 partially reconstructed B mesons is obtained in 3.5·10 hadronic Z decays recorded using the OPAL detector at LEP. The invariant mass distributions of Bπ and BK combinations show enhancements consistent with the decays of P-wave resonances of a b antiquark and a light quark. We observe an excess of 1738±195 Bπ pairs with invariant masses in the range 5.60-5.85 GeV and an excess of 149±31 BK pairs with invariant masses in the range 5.80-6.00 GeV. Labeling the observed enhancements generically as B we find where B indicates the sum of B and B and the errors include statistical and systematic contributions. From a study of π-B charge-flavor correlations we conclude that the production flavor of a B meson can be tagged with the charge of a pion in an appropriately chosen kinematic region, and that the performance of this flavor tag compares favorably in the $$Z^0 \to q\bar q$$ environment with lepton-based tags. [ABSTRACT FROM AUTHOR]

Using 27 490 Z→ττ decays, accumulated in 1991, 1992 and 1993 with the OPAL detector at LEP, a direct test of CP-invariance in the neutral current reaction e e→ττ is performed by measuring CP-odd observables which are proportional to the weak dipole moment of the τ-lepton. A new method based on optimal CP-odd observables constructed from the τ flight and spin directions is employed. More sensitive measurements of the real and, for the first time, the imaginary part of the weak dipole moment with highest possible signal to noise ratio are obtained. No evidence for a non-zero expectation value of the considered observables and hence for CP-violation is observed. An upper limit on the weak dipole moment of |Re( d)|<7.8×10 e·cm and |Im( d)|<4.5×10 e·cm with 95% confidence level is obtained. [ABSTRACT FROM AUTHOR]

From 1 105 045 hadronic Z decays observed with the OPAL detector at the LEP ee collider, 21 732 four-jet events are selected. A simultaneous fit of three selected angular variables from these events by the second order QCD matrix element calculation yields C/ C=2.11±0.16(stat.)±0.28(syst.) T/ C=0.40±0.11(stat.)±0.14(syst.) for the ratios of colour factors, in agreement with SU(3) expectations of C/ C=9/4 and T/ C=3/8. [ABSTRACT FROM AUTHOR]

An upper limit for the ν mass is determined through the kinematic reconstruction of the decay τ→5 π ν in the OPAL detector at LEP. The limit is obtained using a new method based on the comparison of the two-dimensional distribution of energy and invariant mass of the five-pion system with expectations from different neutrino mass hypotheses. From a sample of five events surviving the selection criteria we obtain an upper limit of 74 MeV at 95% confidence level. It is the first measurement at LEP energies, where the larger average multiplicity of $$e^ + e^ - \to q\bar q$$ events makes the suppression of this background more robust compared to lower energies. [ABSTRACT FROM AUTHOR]

We report on a measurement of the tau lepton polarization and its forward-backward asymmetry at the Z resonance using the OPAL detector. This measurement is based on analyses of the $$\tau \to e\bar v_e v_\tau $$ , $$\tau \to \mu \bar v_\mu v_\tau $$ , τ→π(K) v and τ→ ρ v from a sample of 30663 ee→ττ events collected during the years 1990 to 1992. Assuming that the tau lepton decays according to V-A theory, we measure the average τ polarization to be < P>=(−14.9±1.9±1.3)% and the τ polarization forward-backward asymmetry to be A=(−8.9±2.2±0.9)%, where the first error is statistical and the second systematic. These results are consistent with the hypothesis of lepton universality. When combined under the assumption of universality, our results can be interpreted as a measurement of sin θ=0.2321±0.0023 within the context of the Standard Model. [ABSTRACT FROM AUTHOR]

The fraction of $$Z^0 \to b\bar b$$ ; events in hadronic Z decays has been measured using the data collected by OPAL in 1992 and 1993. The presence of electrons or muons from semileptonic decays of bottom hadrons and the detection of bottom hadron decay vertices were used together to obtain an event sample enriched in $$Z^0 \to b\bar b$$ decays. To reduce the systematic error on the measurement of the $$Z^0 \to b\bar b$$ fraction, the efficiency of the $$b\bar b$$ event tagging was obtained from the data by comparing the numbers of events having a bottom signature in either one or both thrust hemispheres. A value of was obtained, where the first error is statistical and the second systematic. The uncertainty on the decay width $$\Gamma (Z^0 \to c\bar c)$$ is not included in these errors. A fractional variation of this width by ±8% about its Standard Model prediction would result in a variation of the measured $$Z^0 \to b\bar b$$ fraction of ±0.0015. [ABSTRACT FROM AUTHOR]

A measurement of the single photon production cross-section is presented based on a data-sample of 40.5 pb collected with the OPAL detector at centre-of-mass energies within 3 GeV of the Z mass. Single photon events arise from initial state radiation and the production of an 'invisible' final state consisting of neutrinos or possibly particles such as sneutrinos or photinos. The single photon topology is also sensitive to new Z decays such as $$Z^0 \to \bar vv* \to \bar vv\gamma $$ or Z→γX, X→invisible particles. A total of 447 single photon candidates were observed with energy exceeding 1.75 GeV in the polar angle region |cosθ|<0.7. The estimated background from processes with visible reaction products, mainly ee→eeγ, is 37±6 events. Interpreting the cross-sections as being solely due to Z decay to invisible particles and the expected W-contributions, the Z invisible with is determined to be 539±26±17 MeV corresponding to N=3.23±0.16±0.10 light neutrino generations. The differential cross-section with photon energy is presented. Upper limits are set on additional invisible contributions to the Z width, on possible non-resconant processes, and on Z decays to single photons. The energy spectra are used to constrain exotic sources of high energy single photons. In particular, the radiative twobody decay of the Z to a new particle X, with mass below 64 GeV and an invisible signature, has a Z branching ratio of less than 4.3×10 at 95% confidence level. [ABSTRACT FROM AUTHOR]

In hadronic Z decays collected by the OPAL experiment at LEP, event shape variables such as jet rates, jet masses, thrust and the energy-energy correlation for $$Z^0 \to b\bar b$$ events are compared to those for all flavours using secondary vertex information to tag the b quarks. The measured distributions are found to be well described by an O"(α) calculation for heavy quarks as well as by parton shower simulations. We also determine the ratio of the strong coupling constant for b quarks and all quarks, α/α, from these distributions. We find where the errors are the statistical and systematic errors. The result can be converted into the ratio for b quarks relative to the complementary flavours udsc α/α=0.992±0.007. [ABSTRACT FROM AUTHOR]

A search for the neutral Higgs bosons h and A, predicted by the Minimal Supersymmetric Extension of the Standard Model (MSSM), has been performed by the OPAL Collaboration at LEP. The analysis was based on approximately 75 pb of data taken at centre-of-mass energies in the vicinity of the Z resonance. No Higgs boson signals have been detected. Using, in addition, an upper limit on the contribution of non-Standard Model processes to the Z boson width, almost the entire MSSM parameter space that can be reached at present LEP energies has been excluded. In particular, at the 95% confidence level, our results imply that $$m_{h^0 } > 44.5$$ GeV/c and $$m_{A^0 } > 24.3$$ GeV/c, for tan β≥1. The sensitivity to this assumption is discussed and the search results are also interpreted in the context of general two-doublet models. [ABSTRACT FROM AUTHOR]

This paper describes an analysis of sub-jet multiplicities, which are expected to be sensitive to the properties of soft gluon radiation, in hadronic decays of the Z. Two- and three-jet event samples are selected using the k jet clustering algorithm at a jet resolution scale y. The mean sub-jet multiplicity as a function of the sub-jet resolution, y, is determined separately for both event samples by reapplying the same jet algorithm at resolution scales y< y. These measurements are compared with recent perturbative QCD calculations based on the summation of leading and next-to-leading logarithms, and with QCD Monte Carlo models. The analytic calculations provide a good description of the sub-jet multiplicity seen in three- and two-jet mvents in the perturbative region ( y≈ y)), and the measured form of the data is in agreement with the expectation based on coherence of soft gluon radiation. The analysis provides good discrimination between Monte Carlo models, and those with a coherent parton shower are preferred by the data. The analysis suggests that coherence effects are present in the data. [ABSTRACT FROM AUTHOR]

We describe a cone-based jet finding algorithm (similar to that used in $$\bar p$$ p experiments), which we have applied to hadronic events recorded using the OPAL detector at LEP. Comparisons are made between jets defined with the cone algorithm and jets found by the 'JADE' and 'Durham' jet finders usually used in e e experiments. Measured jet rates, as a function of the cone size and as a function of the minimum jet energy, have been compared with O(α) calculations, from which two complementary measurements $$\alpha _s \left( {M_{Z^0 } } \right)$$ have been made. The results are $$\alpha _s \left( {M_{Z^0 } } \right)$$ =0.116±0.008 and $$\alpha _s \left( {M_{Z^0 } } \right)$$ =0.119±0.008 respectively, where the errors include both experimental and theoretical uncertainties. Measurements are presented of the energy flow inside jets defined using the cone algorithm, and compared with equivalent data from $$\bar p$$ p interactions, reported by the CDF collaboration. We find that the jets in e e are significantly narrower than those observed in $$\bar p$$ p. The main contribution to this effect appears to arise from differences between quark- and gluon-induced jets. [ABSTRACT FROM AUTHOR]

The inclusive production rates of π, K and p $$\bar p$$ in Z decays have been measured with the OPAL detector at LEP. Using the energy loss measurement in the jet chamber, the momentum range up to the beam energy (45.6 GeV/c) has been covered. Differential cross sections and total particle yields are given. Comparisons of the inclusive momentum spectra and the total rates with predictions of the JETSET and the HERWIG Monte Carlo model are presented. The total single rates are found to be 17.05±0.43 π, 2.42±0.13 K and 0.92±0.11 p $$\bar p$$ per hadronic event. Predictions of JETSET for cross sections and total rates agree very well for π; however, for momenta greater than 4 GeV/c, K rates are underestimated and $$\bar p$$ rates are overestimated. Combined with data of other particle species there is evidence that the peak positions in the ξ=ln(1/ x) distributions show a different mass dependence for mesons and baryons. However, both JETSET and HERWIG Monte Carlo predictions agree with the observed data. [ABSTRACT FROM AUTHOR]