Coherent Cherenkov radiation from cosmic-ray-induced air showers.

Very energetic cosmic rays entering the atmosphere of Earth will create a plasma cloud moving with almost the speed of light. The magnetic field of Earth induces an electric current in this cloud which is responsible for the emission of coherent electromagnetic radiation. We propose to search for a new effect: Because of the index of refraction of air, this radiation is collimated in a Cherenkov cone. To express the difference from usual Cherenkov radiation, i.e., the emission from a fast-moving electric charge, we call this magnetically induced Cherenkov radiation. We indicate its signature and possible experimental verification.

Nasogastric tube feeding in children with cancer: the effect of two different formulas on weight, body composition, and serum protein concentrations.

BACKGROUND: Treatment of cancer cachexia partly involves the administration of adequate amounts of energy. The aim of this study was to assess the tolerance and efficacy of two equal volumes of tube feeding, one with a standard (1 kcal/mL) and one with a high energy density (1.5 kcal/mL), during the intensive phase of treatment. METHODS: Nutritional status was assessed weekly, in 27 children with a solid tumor, by measuring weight, height, midupper arm circumference, biceps and triceps skinfold, and serum proteins. Tolerance was assessed by recording the occurrence of vomiting and by expressing the administered volume as a percentage of the required volume. RESULTS: Both formulas were equally well tolerated, leading to a significantly higher energy intake in the energy-enriched formula group. In both formula groups, all anthropometric variables increased significantly (range of mean increase, 5.2% to 25.5%; p < .05) during the first 4 weeks of intervention. Between 4 and 10 weeks, variables continued to increase significantly in the energy-enriched group, resulting in adequate repletion, in contrast to the standard formula group. The concentration of serum proteins, low at initiation of tube feeding, returned to the normal range within 2 to 4 weeks with no significant differences between the two groups. CONCLUSIONS: The energy-enriched formula was more effective in improving the nutritional status of children with cancer during the intensive phase of treatment than the standard formula. Intensive, protocolized administration of an energy-enriched formula should therefore be initiated as soon as one of the criteria for initiation of tube feeding is met.

Stress prevention in bus drivers: evaluation of 13 natural experiments.

The research aim was to select, compare, and analyze interventions and preventive actions from international bus companies to decrease bus drivers' occupational stress and sickness absenteeism. Through networking, international surveys, and literature study, 13 "natural experiments" were identified with an acceptable research design rating. Interventions were both work and person directed. Principles of worker participation were often followed. The variety in intervention programs, outcome measures, case evaluations, and methodological flaws makes it difficult to present a general picture of program effectiveness. However, analyses on more objective and more subjective outcomes do point at positive effects. This study suggests that stress prevention that combines adequate interventions and proper implementation may be beneficial to both the employee and the company.

Extraction of weak transition strengths via the (3He, t) reaction at 420 MeV.

Differential cross sections for transitions of known weak strength were measured with the (3He, t) reaction at 420 MeV on targets of 12C, 13C, 18O, 26Mg, 58Ni, 60Ni, 90Zr, 118Sn, 120Sn, and 208Pb. Using these data, it is shown that the proportionalities between strengths and cross sections for this probe follow simple trends as a function of mass number. These trends can be used to confidently determine Gamow-Teller strength distributions in nuclei for which the proportionality cannot be calibrated via beta-decay strengths. Although theoretical calculations in the distorted-wave Born approximation overestimate the data, they allow one to understand the main experimental features and to predict deviations from the simple trends observed in some of the transitions.

Nature of the pygmy dipole resonance in 140Ce studied in (alpha, alpha' gamma) experiments.

A concentration of electric-dipole excitations below the particle threshold, which is frequently denoted as the pygmy dipole resonance, has been studied in the semimagic nucleus 140Ce in (alpha, alpha' gamma) experiments at E alpha = 136 MeV. The technique of alpha-gamma coincidence experiments allows the separation of E1 excitations from states of other multipolarities in the same energy region and provides an excellent energy resolution to allow a detailed analysis for each state. The experimental results show that the PDR splits into two parts with different nuclear structure: one part which is excited in (alpha, alpha' gamma) as well as (gamma, gamma') experiments and one part which is excited only in (gamma, gamma').

Gamow-Teller strengths in the A = 14 multiplet: a challenge to the shell model.

A new experimental approach to the famous problem of the anomalously slow Gamow-Teller (GT) transitions in the beta decay of the A=14 multiplet is presented. The GT strength distributions to excited states in 14C and 14O were studied in high-resolution (d,2He) and (3He,t) charge-exchange reactions on 14N. No-core shell-model calculations capable of reproducing the suppression of the beta decays predict a selective excitation of Jpi=2+ states. The experimental confirmation represents a validation of the assumptions about the underlying structure of the 14N ground state wave function. However, the fragmentation of the GT strength over three 2+ final states remains a fundamental issue not explained by the present no-core shell model using a 6homega model space, suggesting possibly the need to include cluster structure in these light nuclei in a consistent way.

Reduction of potassium in drinks by pre-treatment with calcium polystyrene sulphonate.

Dietary potassium intake in patients with chronic renal failure is generally reduced by oral administration of potassium-binding resins. These drugs may cause disturbances of bowel function and have an unpleasant taste. Pre-treatment of drinks with these resins and their subsequent removal may prevent these inconveniences. In four formulas (whole milk, humanised infant formula, apple juice, and orange juice) we were able to lower the potassium content by 50% with calcium polystyrene sulphonate. No important increase of sodium content was observed, as was reported with the use of sodium polystyrene sulphonate. There was a, potentially beneficial, increase of the calcium concentration.

Immune escape mechanisms in Hodgkin's disease.

BACKGROUND: The nodular sclerosis and mixed cellularity subtypes of Hodgkin's disease are histologically characterised by a small population of neoplastic cells, the so-called Reed-Sternberg cells and their mononuclear variants (RS cells) and an extensive admixture of other cell types including lymphocytes, plasma cells, eosinophils, and histiocytes. The nature of this infiltrate is largely known, but the mechanisms and functional effects are not. The small lymphocytes immediately surrounding the RS cells are mostly CD4+ T cells that express early activation markers. The absence of prominent specific cytotoxic T cell or natural killer (NK) cell populations seems to argue against a Th1-type response, whereas the sometimes prominent admixture of plasma cells and eosinophils is suggestive of a Th2-type response. Enrichment of the CD4 T-cell population may result from selective influx of CD4 T cells or from selective depletion of CD8 and NK cells. RESULTS AND DISCUSSION: The T cells surrounding RS cells have an immuno-phenotype and cytokine production capability consistent with a Th2-type response. RS cells express several members of the TNF receptor family such as the FAS ligand (CD95L) that may induce apoptosis of activated, FAS expressing, CD8+ T cells and NK cells. The RS cells also produce TGF beta and interleukin-10 that may downmodulate the Th1 response. In addition, the Reed-Sternberg cells produce the chemokine TARC that could lead to the specific attraction of a Th2 T-cell subset. CONCLUSION: RS cells have several mechanisms that may allow it to escape an effective immune response. The relative contributions of each of these and other potential mechanisms are not yet known.

Excitation and decay of the isovector giant monopole resonances via the 208Pb(3He,t p) reaction at 410 MeV.

The excitation and subsequent proton decay of the isovector spin-flip giant monopole resonance (IVSGMR) is studied via the 208Pb(3He,t) reaction at 410 MeV. In the inclusive spectrum (60+/-5)% of the non-energy-weighted sum-rule strength for this 2 variant Planck's over 2h omega resonance was found in the region 29

Search for three-nucleon force effects in analyzing powers for p-->d elastic scattering.

A series of measurements have been performed at KVI to obtain the vector analyzing power A(y) of the (2)H(p-->,pd) reaction as a function of incident beam energy at energies of 120, 135, 150, and 170 MeV. For all these measurements, a range of theta(c.m.) from 30 degrees to 170 degrees has been covered. The purpose of these investigations is to observe possible spin-dependent effects beyond two-nucleon forces. When compared to the predictions of Faddeev calculations, based on two-nucleon forces only, significant deviations are observed at all energies and at center-of-mass angles between 70 degrees and 130 degrees. The addition of present-day three-nucleon forces does not improve the description of the data, demonstrating the still insufficient understanding of the properties of three-nucleon systems.