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In the course of the past two decades, biodegradable polymers have established to serve in form of compostable or soil-biodegradable items as sustainable alternatives to standard plastics in applications where their property of biodegradability adds value. BASF has been a pioneer in this field of action with their commercially available products ecoflex® and ecovio®. Based on continuous research and development at the edge between polymer chemistry and microbiology, not only new developments were realized in the recent past but also a deep understanding about biodegradation under various conditions could be generated. This chapter provides an up-to-date picture about the chemistry and biodegradation, about processing, applications as well as the sustainability contribution of ecoflex® and ecovio®. [ABSTRACT FROM AUTHOR]

Copyright of Zeitschrift für Herz-, Thorax- und Gefaesschirurgie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Zeitschrift für Herz-, Thorax- und Gefaesschirurgie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Prävention und Gesundheitsförderung is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The nomadic, swarm-raiding army ant Labidus praedator (Smith, 1858) is an important arthropod predator in the Neotropics with a strong ecological impact on invertebrate communities. However, despite its high abundance and ubiquity over a large distribution range, it received relatively little scientific attention. Moreover, the taxonomic status is confusing because some morphological descriptions point towards the co-occurrence of several distinct taxa which are lumped together as L. praedator in most classical keys. Yet, clarifying genetic studies are lacking. Here, we show strong genetic differentiation within an L. praedator population in Mexico. Both microsatellite genotype patterns and phylogenetic analyses (concatenated nuclear and mtDNA sequences, including the coxI genetic barcoding region), reveal the occurrence of two strongly isolated lineages. Colonies from the very same location, clearly identified as the same species ( L. praedator) according to classical morphological keys, exhibit an extremely high average sequence divergence (9.7-12.8 %), which was well in the range of divergence among GenBank sequences from other Labidus species. Thus, our data very likely show genetic differentiation at species level or cryptic speciation within L. praedator, which should be recognized when investigating biodiversity and ecological importance of army ants (or other arthropods) in the Neotropics. [ABSTRACT FROM AUTHOR]

The authors present 19 cases of hyperinsulinism in children worked up with selective pancreatic venous samplings (PVS). Focal lesions were found in 7, diffuse secretion in 8 and normal insulin levels in 4. In three patients with focal hypersecretion less extensive surgery could be performed and confirmed the presence of focal lesions in two. These preliminary results are encouraging and PVS seems to be a valuable technic for detection of focal lesions in the pancreas of children with hyperinsulinism. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented regarding the effectiveness of rituximab with multiagent chemotherapy regimens in the treatment of advanced mature B-cell non-Hodgkin lymphoma (B-NHL) in children and adolescents.

Copyright of Der Chirurg is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: Impaired cerebrovascular reactivity (CR) has been reported to be associated with adverse outcome in patients with aneurysmal subarachnoid hemorrhage (aSAH). However, CR may be determined using different paradigms and it is unclear, which measurement method most suitable reflects the clinical course or is able to predict clinical deterioration.Methods: Twenty-one aSAH patients were included in this study. Following occlusion of the aneurysms with or without implantation of nicardipine prolonged release implants (NPRIs), mean arterial and mean intracranial pressure, regional tissue oxygenation, and regional cerebral blood flow was determined. Based on these data, pressure-, oxygen-, and flow-related autoregulatory indices (PRx, ORx, FRx) were simultaneously calculated and correlated with outcome parameters including the Glasgow outcome score (GOS) and the modified Rankin (mRankin) scale.Results: Eight patients showed newly developed cerebral infarcts. Low values of GOS and mRankin scale highly correlated with the incidence of cerebral infarcts (GOS, P = 0.001; mRankin, P = 0.003). However, indices of CR did not differ significantly between the infarction (I) and the noninfarction group (NI) (PRx, I, 0.058 +/- 0.096, NI, 0.097 +/- 0.203, P = 0.538; ORx, I, 0.162 +/- 0.316, NI, 0.094 +/- 0.176, P = 0.690; FRx, I, 0.395 +/- 0.200, NI, 0.265 +/- 0.177, P = 0.119). No correlation was found between indices and clinical outcome parameters (all not significant). However, ORx and FRx correlated well (P = 0.016).Conclusions: Due to the low number of included subjects, the obtained results are preliminary. However, they indicate that either the present technique of index-determination is not sensitive enough or that there is no strong relation between the measured indices and clinical outcome. Future verification is required of continuous against already established non-continuous monitoring techniques of CR in order to relate both to clinical outcome. [ABSTRACT FROM AUTHOR]

Several reviews devoted to various aspects of ecdysone research have been published during the last few years. Therefore, this article concentrates mainly on the considerable progress in ecdysone research observed recently, and will cover the results obtained during the last 2 years. The main emphasis is put on the molecular mode of ecdysteroid receptor-mediated hormone action. Two examples of interaction with other hormonal signalling pathways are described, namely crosstalk with juvenile hormone and insulin. Some selected, recently investigated examples of the multitude of hormonal responses are described. Finally, ecological aspects and some practical applications are discussed. [ABSTRACT FROM AUTHOR]

Objective. To study the effects of clazosentan, a new selective endothelin receptor subtype A antagonist, on cerebral perfusion and cerebral oxygenation following severe aneurysmal subarachnoid haemorrhage (aSAH). Methods. All 12 patients treated at our institution in the context of a phase IIa, multicenter, randomized trial on clazosentan’s safety and efficacy in reducing the incidence of angiographic cerebral vasospasm were included in this substudy. The phase IIa study ( n = 34) consisted of two parts: a double-blind, randomized Part A (clazosentan 0.2 mg/kg/h versus placebo) and an open-label Part B (clazosentan 0.4 mg/kg/h for 12 h followed by 0.2 mg/kg/h) for patients with established vasospasm. In parallel to the phase IIa study protocol, which included assessment of vasospasm by angiography and transcranial Doppler sonography, we determined regional cerebral blood flow (rCBF), cerebrovascular resistance, and regional tissue oxygenation. Results. Cerebral perfusion was comparable between treatment groups during the early post-bleeding period (rCBF placebo, 22.6 ± 3.5 ml/100 g/min versus rCBF clazosentan, 23.9 ± 1.1 ml/100 g/min). By the time of control angiography (day 8 after aSAH), rCBF decreased by 50% in the placebo group (11.3 ± 6.7 ml/ 100 g/min) while it remained stable in the clazosentan group (23.5 ± 12.9 ml/100 g/min). During Part B of the study, all 3 patients who developed haemodynamically relevant vasospasm during placebo treatment, showed a sustained improvement in rCBF upon conversion to clazosentan. Conclusions. These preliminary data suggest that clazosentan reduces the extent of vasospasm-associated impairment of cerebral perfusion following aSAH. Furthermore, clazosentan may exert beneficial actions on overt vasospasm-associated hypoperfusion. [ABSTRACT FROM AUTHOR]

Copyright of Der Radiologe is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Investigates the effects of convective clouds on the three-dimensional distribution of the spectral actinic flux and on photolysis frequencies for various chemical species. Use of the Spherical Harmonic Discrete Ordinary Method solution technique; Wavelength dependency of the cloud effect on the actinic flux; Computation of photolysis rates.

Experimental results on spectra and wave functions of a ray-splitting microwave billiard are presented. The billiard is formed by a flat rectangular microwave cavity with a quarter-circle insert made of teflon in one of the corners. Using the Gutzwiller trace formula, the contribution of the periodic orbits of the billiard to the density of states are determined. The wave functions, many of them showing scars associated with periodic orbits, are interpreted in terms of the semiclassical Green function. [ABSTRACT FROM AUTHOR]

A method is developed for separating vN interactions from interactions involving an intranuclear cascade in vNe scattering at a mean neutrino energy of 145 GeV. The fraction of events featuring a cascade is evaluated by using a sample of vNe charged-current interactions. It is found that the multiplicity of charged particles in the forward direction takes the same value for events with and without a cascade for 4 < W² < 550 GeV². In the backward direction, cascade events have the charge multiplicity higher than the multiplicity for cascade-free events by 2.36 units. It is found that particles with momenta less than 2 GeV/c make a dominant contribution to the rescattering process. A depletion of the fastest particles for W² < 50 GeV² is observed, in accord with the formation-time concept. [ABSTRACT FROM AUTHOR]

A set-up is described allowing the automatic registration of wavefunctions of quasi-two-dimensional microwave billiards of arbitrary shape. Tests of the apparatus with rectangular shaped billiards showed that a precision of some percent in the wavefunction amplitudes can be obtained, as far as isolated resonances are considered. For the case of overlapping resonances, however, the measurement yields wavefunctions which are close to a symmetric and an antisymmetric linear combination of the original rectangle eigenfunctions. The cause for this at first sight surprising result is discussed. [ABSTRACT FROM AUTHOR]

Angiography remains a very important means of evaluation of ischemic strokes: it confirms the diagnosis showing the occluded artery. It eventually shows the anastomotic pathways for cerebral circulation and it often finds the causes of stroke, among which the most frequent are atherosclerosis (70%) and fibromuscular hyperplasia (10%). The safer way to perform angiography is the retrograde route. Indications for angiography must be discussed according to the type of stroke, its onset, and the arterial territory involved. [ABSTRACT FROM AUTHOR]

Chitinase and N-acetyl- β-D-glucosaminidase activity were quantified in Palaemon serratus (Pennant) integument and midgut gland during the moulting cycle. Studies were performed on specimens collected near Concarneau, France, in July 1989. The changes in specific activity are different in the two organs: in the midgut gland enzymatic activity is high throughout the whole moulting cycle with a weak peak at the early premoult Stage D1′, whereas in the integument the activity of both enzymes is very low throughout post- and intermoult stages and rises only after premoult Stage D1′. The highest specific activity is reached in D1‴ for chitinase and somewhat earlier (D1″) for N-acetyl- β-D-glucosaminidase. The increase in specific chitinolytic activity coincides with an increase in ecdysteroids. [ABSTRACT FROM AUTHOR]

In the first holographic bubble chamber experiment - the HOBC experiment - we have accumulated a total of 40000 holograms with particle interactions. We have determined the total charm pair cross section in pN collisions to be 23.3 μb and 3.6 μb for 360 and 200 GeV/c incident protons respectively. We have assumed a linear dependence of the cross section on the atomic number of the target. This experiment has demonstrated the feasibility of holographic recording in small bubble chambers. Assuming that the charm cross section can be described by the standard QCD factorized expression with gluon fusion and quark-antiquark annihilation, we have used our measured charm cross sections with other measurements to determine the effective charmed quark mass to be 1.8 GeV/c. The K factor, which describes the importance of the higher order corrections, is calculated to be 9.8 (See noted added in proof.) [ABSTRACT FROM AUTHOR]

The production properties of K, $$\bar \Lambda$$ and K p interactions at 32 GeV/c are investigated using the final statistics of the experiment. We present total and semi-inclusive cross sections and aver-age multiplicities. Estimates are given of the diffractive dissociation contributions to total and differential cross sections. The x-, p, and transverse mass dependence of inclusive and semi-inclusive distributions is discussed as well as properties of 'prompt' K's. The ratio of 'prompt' K ( K) to 'prompt' K cross sections is measured to be 1.03±0.12 (0.98±0.17). From a comparison of $$\bar \Lambda$$ production in K p interactions at 32 GeV/c, we estimate a strange sea-quark suppression of 0.26 ±0.02. The double differential cross sections of K's is studied as a function of Feynman- x and p, and a Triple-Regge fit performed. The data are compared in detail to versions of the Lund-model for low- p hadronic collisions. [ABSTRACT FROM AUTHOR]

We present final results on inclusive production of K(890), K(1430) and K(890) in $$\bar K^ + p$$ interactions at 32 GeV/c, based on a statistics of ∼27 events/μb. Total cross sections, p-and x-dependence of inclusive distributions are compared with experiments at other energies and with the Lund fragmentation model. Spin density matrix elements of the K(890) are also discussed. The results suggest that 'recombination' of both initial state valence quarks $$\bar s$$ and u of the K into K(890), responsible in the Lund model for ∼45% of the K(890) cross section, is strongly suppressed. [ABSTRACT FROM AUTHOR]

Results are reported on a study of events with high- p in K p collisions at centre of mass energy of 11.5 GeV/c. Interesting similarities with ISR results are observed both in charge and rapidity correlations among particles with a p>1 GeV/c trigger. Properties of high- p jet fragmentation are found to be similar to the ones observed at the ISR and in e e annihilation. [ABSTRACT FROM AUTHOR]

Inclusive and semi-inclusive cross sections and distributions of γ's and π's in K p interactions at 70 GeV/c are presented. The results are compared to other experiments and to the Lund model for low- p hadron collisions. [ABSTRACT FROM AUTHOR]

Energy, charge and strangeness flow in K p interactions at 32 and 70 GeV/c, and π p interactions at 32 GeV/c are studied in terms of the angular variable λ=| x|/ p. The data on dQ/dλ and dE/dλ show only a weak indication of scale breaking between 32 and 70 GeV/c. For inclusive 'non-diffractive', inclusive 'diffractive' and exclusive 'non-diffractive' jets, the fraction of charge in any angular region ΔΩ away from the central region is found to be proportional to the energy fraction in the same interval. The data on dQ/dE versus λ are compatible with some versions of dual-sheet models and agree also with the LUND Monte-Carlo model. The data are also compared with $$v(\bar v)p$$ interactions in BEBC. In exclusive channels the average ratio dQ/dS=0.78±0.04 is consistent, in the framework of fragmentation models, with a larger probability for the fragmentation of the $$\bar s$$ -valence quark than the u-valence quark in the K-meson. [ABSTRACT FROM AUTHOR]

Results are presented on K p elastic scattering and on the reaction K p→ K pππ at 70 GeV/c. For the elastic channel, we measured the total ((2.29±0.04)mb) and differential dσ/dt cross sections. The reaction K p→ K pππ has a total cross section of (470±23) μb and is shown to be dominated by diffractive dissociation processes. The contributions of the quasi-two-body channels and and of the Double-Pomeron Exchange (DPE) processes are estimated. [ABSTRACT FROM AUTHOR]

Results are presented on the inclusive production of π mesons and protons in $$\bar p$$ p interactions at an incident antiproton momentum of 32 GeV/c in the MIRABELLE bubble chamber, based on a sample of 55,000 inelastic events. The spectra of π(π) and p( $$\bar p$$ ) are separated in the whole kinematically admitted region of phase space by a statistical method. The semi-inclusive and inclusive cross sections and the main average characteristics of π and p production are calculated. The invariant differential cross sections are studied as functions of the Fevnman scaling variable x, the rapidity and the transverse momentum. The x distribution of π mesons in the proton fragmentation region does not show any significant contribution from quark exchange or annihilation processes. A possible contribution of hard quark scattering on mesons or baryons is observed for large transverse momenta. [ABSTRACT FROM AUTHOR]

New experimental results are presented on inclusive production properties of $$\bar \Sigma ^{ * + } $$ (1385) and $$\bar \Sigma ^{ * + } $$ (1385) in K p interactions at 32 GeV/c. The analysis is based on significantly larger statistics than previously available. A comparison is also made of invariant x-distributions of K/ $$\bar K^0 $$ , $$\bar \Lambda $$ and $$\bar \Xi ^ + $$ and of $$\bar \Sigma ^{ * \pm } $$ (1385) and K(892). These spectra exhibit regularities expected from the quark-recombination picture when it is assumed that the strange mesons and antibaryons are produced off the strange $$\bar s$$ -valence-quark in the incident K meson. Transverse momentum distributions are also presented for K(892) and $$\bar \Sigma ^{ * \pm } $$ (1385) and found to be very similar. The results on strange antibaryon average multiplicities disagree strongly with a recent version of the additive quark model. [ABSTRACT FROM AUTHOR]

The inclusive K, ¶, and $$\bar \Lambda$$ production has been studied in a $$\bar pp$$ experiment performed in the Mirabelle bubble chamber at an incident beam momentum of 32.1 GeV/c. Total, topological and differential cross sections are presented and compared with those obtained at other energies. The invariant structure functions have been parametrised in the fragmentation region by a power law and are consistent with the expectations based on quark counting rules. [ABSTRACT FROM AUTHOR]

Inclusive and semi-inclusive production of Λ and $$\bar \Lambda$$ in K p interactions is studied at an incident momentum of 70 GeV/c. Cross sections and single particle distributions are presented and compared with data at lower energies. Scaling is observed between 32 and 70 GeV/c in the Feynman x variable in the target and the beam fragmentation regions for Λ and $$\bar \Lambda$$ inclusive production respectively. An increase of Λ ( $$\bar \Lambda$$ ) production is observed in the beam (target) fragmentation regions, whereas the data at 70 and 32 GeV/c are reasonably close in the central region. The dependence of the Λ( $$\bar \Lambda$$ ) polarization as a function of x is measured and found to be in general agreement with the results at 32 GeV/c. The (Λ $$\bar \Lambda$$ ) pair production cross section increases significantly from 32 to 70 GeV/c. The Λ and $$\bar \Lambda$$ production associated with an identified proton is also studied. [ABSTRACT FROM AUTHOR]

We present results of an investigation of diffraction dissociation in exclusive channels in K p interactions at 32 GeV/c. Total cross sections are determined for K→ Kππ, K2π2π, Kππ K2ππ, K K K, Kp $$\bar p$$ , $$\bar \Lambda $$ p, and p→ pππ, p2π2π, pKK, ΛK, ΛKππ dissociation modes, ranging from a high of ≃ 300 μb to ∼ 3 μb. The dσ/dt′ differential cross sections of most of the systems studied exhibit structure, with breaks of slope at t′ ∼ 0.2 to 0.5 GeV; some modes have a sharp forward spike with a slope exceeding 10 GeV. A systematic investigation of two-body dissociation modes K→ A+ B and p→ A′+ B′ shows that these cross sections decrease with increasing threshold mass M+ M, that they are comparable for kaon and proton dissociations at similar diffractive excitation masses and are systematically suppressed by a factor 3-4 for dissociations requiring an $$s\bar s$$ quark pair creation when compared to $$u\bar u$$ pair creation indicating a breakdown of SU symmetry for the $$q\bar q$$ sea. [ABSTRACT FROM AUTHOR]

The inclusive π and γ production is studied in a $$\bar PP$$ experiment at 32.1 GeV/c performed in the Mirabelle bubble chamber with a sensitivity of ∼2.7 events/μb. Total and topological π cross sections are presented. The π and γ longitudinal and transverse momentum distributions are obtained and compared with $$\bar PP$$ data at 22.4 GeV/c and K P data at 32.1 GeV/c. The inclusive π distributions are also compared to those obtained for charged pions in the same experiment. [ABSTRACT FROM AUTHOR]

Inclusive charged pion production is studied in an exposure of BEBC, filled with hydrogen, to an incident K beam of 70 GeV/c. Total cross sections for pion production and inclusive longitudinal and transverse momentum distributions of π's and of positive particles are presented and compared with data at lower energies. Earlier evidence for scaling in the fragmentation regions is confirmed. The central region π cross section increases proportionally to p; positive particles show almost no energy dependence at x=0. Particle ratios π/π are studied as a function of x and y and a comparison with 70 GeV/c K p data is made. Analysis of structure functions for (ππ) pairs and of particle production associated with π triggers at large | x| in the context of quark/parton models, provides qualitative evidence for the diquark-quark structure of the proton. [ABSTRACT FROM AUTHOR]

The inclusive inelastic processes K p→ pX and K p→ Δ X are studied at an incident momentum of 70 GeV/c. The data comes from the Big European Bubble Chamber BEBC filled with hydrogen, exposed to an rf reparated K beam at the CERN SPS accelerator. The inclusive cross section for protons with laboratory momentum p≦1.2 GeV/c is equal to (6.1±0.1) mb. Inclusive Δ-production is studied for | t|<1.0(GeV/c). Comparisons are made with other K p data and with pp data at 69 GeV/c. Evidence is found for Pomeron exchange at the beam vertex both for slow proton and Δ-production as well as for absorptive pion exchange at the ( p, Δ) vertex. [ABSTRACT FROM AUTHOR]

Total and semi-inclusive cross sections, longitudinal and transverse momentum distributions and spin density matrix elements of the K(892) and K(892) produced in the inclusive reactions K p→ K(892)+ X and K p→ K(892)+ X at 32 GeV/ c are studied in detail. The inclusive spectra of the K(892) and their decay products are compared with pion and neutral kaon production. The K(892) and K(892) are dominantly produced by kaon fragmentation processes. The dependence of average transverse momentum < p> vs. x for resonances has been investigated for the first time. [ABSTRACT FROM AUTHOR]

We study single and double inclusive diffractive production in a 32 GeV/ c K p experiment in MIRABELLE at the Serpukhov accelerator. From reactions K p→ K+ X and K p→ X+ p we determine the total proton and kaon single diffractive dissociation cross sections $$\sigma (p\xrightarrow{{K^ + }}p_D ) = 0.90 \pm 0.12 mb$$ and $$\sigma (K^ + \xrightarrow{p}K_D^ + ) = 0$$ . 90±0.17 mb, respectively. In either case the only notable contributions come from dissociations into 1 and 3 charged particles. Kaon dissociation exhibits a pronounced slope-mass correlation. The search for double diffractive production in reactions K p→( Kππ)+ X and K p→( pπ π)+ X leads in either case to an estimated total double diffractive cross section σ( Kp→Kp) of ≅220 μb. The double dissociation differential cross section exhibits a large slope of ≅10GeV in the nearthreshold mass region, rapidly decreasing to ≅4 GeV with increasing excitation mass. At our c.m. energy $$(\sqrt s \simeq 8 GeV)$$ the ratio σ/σ is 0.85±0.10, the total diffractive cross section σ≡σ+σ=4.41±0.24 mb and the fraction σ( K p)/σ( K p) is 25±2%. The K and K diffractive excitation mass spectra, differential cross sections and total diffractive cross sections are very similar for both single and double dissociations. [ABSTRACT FROM AUTHOR]

Cross sections and charged multiplicity distributions for K p interactions at 70 GeV/ c are presented and compared with K p data at other energies. Comparisons are also made with available π p, pp, and K p data. [ABSTRACT FROM AUTHOR]

Copyright of Der Radiologe is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Using the H1 detector at HERA, charged particle multiplicity distributions in deep inelastic e p scattering have been measured over a large kinematical region. The evolution with W and Q of the multiplicity distribution and of the multiplicity moments in pseudorapidity domains of varying size is studied in the current fragmentation region of the hadronic centre-of-mass frame. The results are compared with data from fixed target lepton-nucleon interactions, e e annihilations and hadron-hadron collisions as well as with expectations from QCD based parton models. Fits to the Negative Binomial and Lognormal distributions are presented. [ABSTRACT FROM AUTHOR]

First results on inclusive $$\mathop {D^0 }\limits^{( - )} $$ and D* production in neutral current deep inelastic ep scattering are reported using data collected by the H1 experiment at HERA in 1994. Differential cross sections are presented for both channels and are found to agree well with QCD predictions based on the boson gluon fusion process. A charm production cross section for 10 GeV≤Q≤100 GeV and 0.01≤ y≤0.7 of $$\sigma (ep \to ec\bar cX) = (17.4 \pm 1.6 \pm 1.7 \pm 1.4) nb$$ is derived. A first measurement of the charm contribution $$F_2^{c\bar c} (x,Q^2 )$$ to the proton structure function for Bjorken x between 8·10 and 8·10 is presented. In this kinematic range a ratio $$F_2^{c\bar c} /F_2 = 0.237 \pm 0.021 \pm 0.041$$ is observed. [ABSTRACT FROM AUTHOR]

A search for squarks of R-parity violating supersymmetry is performed in ep collisions at HERA using H1 1994 e data. Direct single production of squarks of each generation by e -quark fusion via a Yukawa coupling λ′ is considered. All possible R-parity violating decays and gauge decays of the squarks are taken into account. No significant deviation from the Standard Model predictions is found in the various multi-lepton and multi-jet final states studied and exclusion limits are derived. At 95% confidence level, the existence of first generation squarks is excluded for masses up to 240 GeV for coupling values λ′≳√4 πα . The limits obtained are shown to be only weakly dependent on the free parameters of the Minimal Supersymmetric Standard Model. Stop squarks are excluded for masses up to 138 GeV for coupling λ′×cos θ to e d pairs ≳0.1×√4 πα , where θ is the mass mixing angle. Light stop squarks are furthermore searched for through pair production in γ-gluon fusion processes. No signal is observed and exclusion limits are derived. Masses in the range 9 to 24.4 GeV are excluded at 95% confidence level for λ′×cos θ >10. [ABSTRACT FROM AUTHOR]

Properties of the hadronic final state in photoproduction events with large transverse energy are studied at the electron-proton collider HERA. Distributions of the transverse energy, jets and underlying event energy are compared to $$\bar pp$$ data and QCD calculations. The comparisons show that the γp events can be consistently described by QCD models including - in addition to the primary hard scattering process - interactions between the two beam remnants. The differential jet cross sections dσ/dE and dσ/dη are measured. [ABSTRACT FROM AUTHOR]

We present a new measurement of the total photoproduction cross section performed with the H1 detector at HERA. For an average centre of mass energy of 200 GeV a value of σ=165±2±11 µb has been obtained. A detailed analysis of the data in adequate kinematic regions enabled a decomposition of the total cross section in its elastic, single diffractive dissociation and remaining non-diffractive parts, based on safe assumptions on the double diffractive dissociation contribution. [ABSTRACT FROM AUTHOR]

The cross sections for the charged current processes {ie566-1} and, for the first time, {ie566-2} are measured at HERA for transverse momenta larger than 25 GeV. [ABSTRACT FROM AUTHOR]

We present an experimental study of the ep→ eγ+ p and ep→ eγ+ X processes using data recorded by the H1 detector in 1993 at the electron-proton collider HERA. These processes are employed to measure the luminosity with an accuracy of 4.5 %. A subsample of the ep→ eγ+ X events in which the hard photon is detected at angles θ ≤ 0.45 mrad with respect to the incident electron direction is used to verify experimentally the size of radiative corrections to the ep→ eX inclusive cross section and to investigate the structure of the proton in the Q domain down to 2 GeV, lower than previously attained at HERA. [ABSTRACT FROM AUTHOR]

A search in the H1 experiment at HERA for scalar and vector leptoquarks, leptogluons and squarks coupling to first generation fermions is presented in a data sample corresponding to an integrated luminosity of 425 nb. For masses ranging up to ∼275 GeV, no significant evidence for the direct production of such particles is found in various possible decay channels. At high masses and beyond the centre of mass energy of 296 GeV a contact interaction analysis is used to further constrain the couplings and masses of new vector leptoquarks and to set lower limits on compositeness scales. [ABSTRACT FROM AUTHOR]