Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 8 de 8
Filter
1.
Phys Rev Lett ; 124(8): 081803, 2020 Feb 28.
Article in English | MEDLINE | ID: mdl-32167372

ABSTRACT

We present the result of an experiment to measure the electric dipole moment (EDM) of the neutron at the Paul Scherrer Institute using Ramsey's method of separated oscillating magnetic fields with ultracold neutrons. Our measurement stands in the long history of EDM experiments probing physics violating time-reversal invariance. The salient features of this experiment were the use of a ^{199}Hg comagnetometer and an array of optically pumped cesium vapor magnetometers to cancel and correct for magnetic-field changes. The statistical analysis was performed on blinded datasets by two separate groups, while the estimation of systematic effects profited from an unprecedented knowledge of the magnetic field. The measured value of the neutron EDM is d_{n}=(0.0±1.1_{stat}±0.2_{sys})×10^{-26} e.cm.

2.
Phys Rev Lett ; 103(8): 081602, 2009 Aug 21.
Article in English | MEDLINE | ID: mdl-19792714

ABSTRACT

A clock comparison experiment, analyzing the ratio of spin precession frequencies of stored ultracold neutrons and 199Hg atoms, is reported. No daily variation of this ratio could be found, from which is set an upper limit on the Lorentz invariance violating cosmic anisotropy field b perpendicular < 2 x 10(-20) eV (95% C.L.). This is the first limit for the free neutron. This result is also interpreted as a direct limit on the gravitational dipole moment of the neutron |gn| < 0.3 eV/c2 m from a spin-dependent interaction with the Sun. Analyzing the gravitational interaction with the Earth, based on previous data, yields a more stringent limit |gn| < 3 x 10(-4) eV/c2 m.

3.
J Environ Sci Health B ; 43(2): 199-204, 2008 Feb.
Article in English | MEDLINE | ID: mdl-18246513

ABSTRACT

This study sought to evaluate the potential of trees planted around commercial poultry farms to trap ammonia (NH(3)), the gas of greatest environmental concern to the poultry industry. Four plant species (Norway spruce, Spike hybrid poplar, Streamco willow, and hybrid willow) were planted on eight commercial farms from 2003 to 2004. Because temperature (T) can be a stressor for trees, T was monitored in 2005 with data loggers among the trees in front of the exhaust fans (11.4 to 17.7 m) and at a control distance away from the fans (48 m) during all four seasons in Pennsylvania. Norway spruce (Picea abies) foliage samples were taken in August 2005 from one turkey and two layer farms for dry matter (DM) and nitrogen (N) analysis. The two layer farms had both Norway spruce and Spike hybrid poplar (Populus deltoides x Populus nigra) plantings sampled as well allowing comparisons of species and the effect of plant location near the fans versus a control distance away. Proximity to the fans had a clear effect on spruce foliar N with greater concentrations downwind of the fans than at control distances (3.03 vs. 1.88%; P < or = 0.0005). Plant location was again a significant factor for foliar N of both poplar and spruce on the two farms with both species showing greater N adjacent to the fans compared to the controls (3.75 vs. 2.32%; P < or = 0.0001). Pooled foliar DM of both plants was also greater among those near the fans (56.17, fan vs. 44.67%, control; P < or = 0.005). Species differences were also significant showing the potential of poplar to retain greater foliar N than spruce (3.52 vs. 2.55%; P < or = 0.001) with less DM (46.00 vs. 54.83%; P < or = 0.05) in a vegetative buffer setting. The results indicated plants were not stressed by the T near exhaust fans with mean seasonal T (13.04 vs. 13.03 degrees C, respectively) not significantly different from controls. This suggested poultry house exhaust air among the trees near the fans would not result in dormancy stressors on the plants compared to controls away from the fans.


Subject(s)
Air Pollutants/metabolism , Ammonia/metabolism , Photosynthesis/physiology , Plant Leaves/metabolism , Trees/metabolism , Air Pollutants/analysis , Air Pollution/prevention & control , Ammonia/analysis , Ammonia/pharmacology , Animals , Biomass , Crosses, Genetic , Nitrogen/analysis , Nitrogen/metabolism , Photosynthesis/drug effects , Picea/metabolism , Poultry , Salix/metabolism , Seasons , Species Specificity , Temperature , Trees/genetics
4.
J Environ Sci Health B ; 43(1): 96-103, 2008 Jan.
Article in English | MEDLINE | ID: mdl-18161579

ABSTRACT

This study evaluated the potential of trees planted around commercial poultry farms to trap ammonia (NH(3)) and dust or particulate matter (PM). Norway spruce, Spike hybrid poplar, hybrid willow, and Streamco purpleosier willow were planted on five commercial farms from 2003 to 2004. Plant foliage was sampled in front of the exhaust fans and at a control distance away from the fans on one turkey, two laying hen, and two broiler chicken farms between June and July 2006. Samples were analyzed for dry matter (DM), nitrogen (N), and PM content. In addition, NH(3) concentrations were measured downwind of the exhaust fans among the trees and at a control distance using NH(3) passive dosi-tubes. Foliage samples were taken and analyzed separately based on plant species. The two layer farms had both spruce and poplar plantings whereas the two broiler farms had hybrid willow and Streamco willow plantings which allowed sampling and species comparisons with the effect of plant location (control vs. fan). The results showed that NH(3) concentration h(- 1) was reduced by distance from housing fans (P < or = 0.0001), especially between 0 m (12.01 ppm), 11.4 m (2.59 ppm), 15 m (2.03 ppm), and 30 m (0.31 ppm). Foliar N of plants near the fans was greater than those sampled away from the fans for poplar (3.87 vs. 2.56%; P < or = 0.0005) and hybrid willow (3.41 vs. 3.02%; P < or = 0.05). The trends for foliar N in spruce (1.91 vs. 1.77%; P = 0.26) and Streamco willow (3.85 vs. 3.33; P = 0.07) were not significant. Pooling results of the four plant species indicated greater N concentration from foliage sampled near the fans than of that away from the fans (3.27 vs. 2.67%; P < or = 0.0001). Foliar DM concentration was not affected by plant location, and when pooled the foliar DM of the four plant species near the fans was 51.3% in comparison with 48.5% at a control distance. There was a significant effect of plant location on foliar N and DM on the two layer farms with greater N and DM adjacent to fans than at a control distance (2.95 vs. 2.15% N and 45.4 vs. 38.2% DM, respectively). There were also significant plant species effects on foliar N and DM with poplar retaining greater N (3.22 vs. 1.88%) and DM (43.7 vs. 39.9%) than spruce. The interaction of location by species (P < or = 0.005) indicated that poplar was more responsive in terms of foliar N, but less responsive for DM than spruce. The effect of location and species on foliar N and DM were not clear among the two willow species on the broiler farms. Plant location had no effect on plant foliar PM weight, but plant species significantly influenced the ability of the plant foliage to trap PM with spruce and hybrid willow showing greater potential than poplar and Streamco willow for PM(2.5)(0.0054, 0.0054, 0.0005, and 0.0016 mg cm(- 2); P < or = 0.05) and total PM (0.0309, 0.0102, 0.0038, and 0.0046 mg cm(- 2), respectively; P < or = 0.001). Spruce trapped more dust compared to the other three species (hybrid willow, poplar, and Streamco willow) for PM(10) (0.0248 vs. 0.0036 mg cm(- 2); P < or = 0.0001) and PM(> 10) (0.0033 vs. 0.0003 mg cm(- 2); P = 0.052). This study indicates that poplar, hybrid willow, and Streamco willow are appropriate species to absorb poultry house aerial NH(3)-N, whereas spruce and hybrid willow are effective traps for dust and its associated odors.


Subject(s)
Ammonia/adverse effects , Nitrogen/metabolism , Photosynthesis/physiology , Plant Leaves/metabolism , Plants/metabolism , Air Pollutants/adverse effects , Air Pollutants/analysis , Ammonia/analysis , Animals , Biomass , Dust/analysis , Particulate Matter , Photosynthesis/drug effects , Plant Development , Plant Leaves/drug effects , Plant Leaves/growth & development , Plants/drug effects , Poultry , Species Specificity , Time Factors
5.
Phys Rev Lett ; 97(13): 131801, 2006 Sep 29.
Article in English | MEDLINE | ID: mdl-17026025

ABSTRACT

An experimental search for an electric dipole moment (EDM) of the neutron has been carried out at the Institut Laue-Langevin, Grenoble. Spurious signals from magnetic-field fluctuations were reduced to insignificance by the use of a cohabiting atomic-mercury magnetometer. Systematic uncertainties, including geometric-phase-induced false EDMs, have been carefully studied. The results may be interpreted as an upper limit on the neutron EDM of |d(n)|< 2.9 x 10(-26)e cm (90% C.L.).

6.
Ned Tijdschr Geneeskd ; 147(7): 286-90, 2003 Feb 15.
Article in Dutch | MEDLINE | ID: mdl-12622005

ABSTRACT

Primary hip prostheses dislocate in 0.4 to 8.7% of the cases. Revision hip prostheses dislocate in 5 to 20% of the cases. High age, female sex, co-morbidity and alcoholism increase the risk of dislocation. The surgical approach of the hip and the experience of the surgeon are important factors in the operation technique. The anterior approach causes the least dislocations, but a disadvantage of this approach is that patients are more likely to walk with a limp afterwards. The selected implant also influences the dislocation risk. The smaller the head, the narrower the neck must be. Furthermore, the femur must not come to be too close to the pelvis. If necessary, a cup can be used with a raised anterior edge. Treatment of a primary dislocation is usually conservative and is based on providing the patient with guidelines. An abduction brace can be prescribed if a patient is not able or willing to comply with these rules. If dislocation is a recurring problem, revision of the prosthesis is often the only solution.


Subject(s)
Arthroplasty, Replacement, Hip/methods , Hip Dislocation/etiology , Hip Prosthesis , Age Factors , Aged , Alcoholism/complications , Arthroplasty, Replacement, Hip/adverse effects , Braces , Female , Hip Dislocation/epidemiology , Hip Dislocation/therapy , Hip Prosthesis/adverse effects , Humans , Incidence , Male , Reoperation , Risk Factors , Sex Factors , Treatment Outcome
7.
Appl Ergon ; 32(5): 525-34, 2001 Oct.
Article in English | MEDLINE | ID: mdl-11534798

ABSTRACT

Lifting, carrying, pushing and pulling at work are assumed to be related to increased risks of musculoskeletal injury, mainly in the low back and shoulder region. The implementation of products to reduce the physical load in heavy work is a well-known strategy to attack this problem. The success of these products depends not only on the product itself, but also on the process of product development and implementation. In this paper, seven cases are described where products have been developed to reduce the physical load on scaffolders, bricklayers, bricklayer's assistants, roofworkers, aircraft loaders, glaziers and assembly line workers. These products are described with special reference to the physical load problem in the occupational task, the process of product development, the nature of the product, the potential effects on physical load and the opinion of workers. From these cases, a list of key factors in product development contributing to the success of a product is composed. These concern among others a direct participation of workers, a wide analysis of risks, an analysis of potential negative side effects, and a systematic stepwise approach.


Subject(s)
Ergonomics/methods , Musculoskeletal Diseases/prevention & control , Stress, Physiological/prevention & control , Work/physiology , Workload , Equipment Design , Evaluation Studies as Topic , Humans , Occupations
8.
Occup Environ Med ; 55(2): 73-83, 1998 Feb.
Article in English | MEDLINE | ID: mdl-9614390

ABSTRACT

OBJECTIVES: Due to recent changes in legislation on occupational health and safety, a national monitor on stress and physical load was developed in The Netherlands to monitor (a) risks and consequences of stress and physical load at work, (b) preventive actions in companies to reduce these risks, and (c) organisational and environmental variables that facilitate preventive actions. METHODS: Information was gathered from employers, employees, and employees' representatives. The monitor was used with a nationally representative sample of companies in industry, wholesale trade, and banking and finance, 782 companies in total. RESULTS AND CONCLUSIONS: The information from the employees, aggregated at the company level, was not found to be correlated with that from the employer from the same companies. Although many employers do recognise risk factors for both physical load and stress as a problem they often seem to underestimate the problem when compared with employees or their representatives. This is particularly the case for psychosocial risk factors. Also, the perception of outcome measures, especially employers who consider emotional exhaustion to be work related, were fewer than the employees' representatives of the same organisation. Preventive measures on physical load are much more popular than measures against stress. It is the responsibility of the employer to take more preventive action of all kinds. They need to recognise risk factors as problems and health outcomes to be related to work. Employees of larger companies should participate with employers to consider effective measures, and more use should be made of support at branch level. For specific preventive measures, specific predictors emerged. Except for measures to prevent work stress, information from employees did not sufficiently contribute to the initiation of preventive measures in the workplace.


Subject(s)
Occupational Health , Stress, Psychological , Workload , Employee Grievances , Female , Health Policy , Humans , Logistic Models , Male , Netherlands/epidemiology , Occupational Health/statistics & numerical data , Retrospective Studies , Risk Factors , Safety Management/methods , Stress, Psychological/epidemiology , Stress, Psychological/etiology , Stress, Psychological/prevention & control , Surveys and Questionnaires
SELECTION OF CITATIONS
SEARCH DETAIL
...