Chronic fatigue syndrome; an approach combining self-management with graded exercise to avoid exacerbations.

Controversy regarding the aetiology and treatment of patients with chronic fatigue syndrome (CFS) continues to affect the medical professions. The Cochrane collaboration advises practitioners to implement graded exercise therapy for CFS sufferers using cognitive behavioural principles. In contrast there is evidence that exercise can induce symptom exacerbations in CFS where too vigorous exercise/activity promotes immune dysfunction, which in turn increases symptoms in patients with CFS. When designing and implementing an exercise programme it is important to be aware of both these seemingly opposing view points in order to deliver a programme without any detrimental effects on CFS pathophysiology. Using evidence from both the biological and clinical sciences, the present manuscript explains that graded exercise therapy for people with CFS can be safely undertaken without detrimental effects to the immune system. Exercise programs should be designed to cater for individual physical capabilities and should also account for the fluctuating nature of symptoms commonly reported by people with CFS. In line with cognitive behaviourally and graded exercise-based strategies, self-management for people with CFS involves encouraging the patients to pace their activities and respect their physical and mental limitations with the ultimate aim of improving their everyday function

On deflection fields, weak-focusing and strong-focusing storage rings for polar molecules

In this paper, we analyze electric deflection fields for polar molecules in terms of a multipole expansion and derive a simple but rather insightful expression for the force on the molecules. Ideally, a deflection field exerts a strong, constant force in one direction, while the force in the other directions is zero. We show how, by a proper choice of the expansion coefficients, this ideal can be best approximated. We present a design for a practical electrode geometry based on this analysis. By bending such a deflection field into a circle, a simple storage ring can be created; the direct analog of a weak-focusing cyclotron for charged particles. We show that for realistic parameters a weak-focusing ring is only stable for molecules with a very low velocity. A strong-focusing (alternating-gradient) storage ring can be created by arranging many straight deflection fields in a circle and by alternating the sign of the hexapole term between adjacent deflection fields. The acceptance of this ring is numerically calculated for realistic parameters. Such a storage might prove useful in experiments looking for an EDM of elementary particles.Comment: 8 pages, 5 figure

Sensitivity of rotational transitions in CH and CD to a possible variation of fundamental constants

The sensitivity of rotational transitions in CH and CD to a possible variation of fundamental constants has been investigated. Largely enhanced sensitivity coefficients are found for specific transitions which are due to accidental degeneracies between the different fine-structure manifolds. These degeneracies occur when the spin-orbit coupling constant is close to four times the rotational constant. CH and particularly CD match this condition closely. Unfortunately, an analysis of the transition strengths shows that the same condition that leads to an enhanced sensitivity suppresses the transition strength, making these transitions too weak to be of relevance for testing the variation of fundamental constants over cosmological time scales. We propose a test in CH based on the comparison between the rotational transitions between the e and f components of the Omega'=1/2,J=1/2 and Omega'=3/2,J=3/2 levels at 532 and 536 GHz and other rotational or Lambda-doublet transitions in CH involving the same absorbing ground levels. Such a test, to be performed by radioastronomy of highly redshifted objects, is robust against systematic effects

Ramsey-type microwave spectroscopy on CO (a3Πa^3\Pi)

Using a Ramsey-type setup, the lambda-doublet transition in the $J=1,\, \Omega=1$ level of the $a^3\Pi$ state of CO was measured to be 394 064 870(10) Hz. In our molecular beam apparatus, a beam of metastable CO is prepared in a single quantum level by expanding CO into vacuum and exciting the molecules using a narrow-band UV laser system. After passing two microwave zones that are separated by 50 cm, the molecules are state-selectively deflected and detected 1 meter downstream on a position sensitive detector. In order to keep the molecules in a single $m_J^B$ level, a magnetic bias field is applied. We find the field-free transition frequency by taking the average of the $m_J^B = +1 \rightarrow m_J^B = +1$ and $m_J^B = -1 \rightarrow m_J^B = -1$ transitions, which have an almost equal but opposite Zeeman shift. The accuracy of this proof-of-principle experiment is a factor of 100 more accurate than the previous best value obtained for this transition

Plantenparasitaire nematoden en golfvelden

Over schimmels en insecten, als belagers van grassen en golfvelden, is relatief veel bekend. Minder bekend zijn nematoden ofwel aaltjes. Vanuit met name Ierland en het Verenigd Koninkrijk, golflanden bij uitstek, worden de laatste jaren regelmatig problemen gemeld met slecht groeiend gras op golfbanen veroorzaakt door nematoden. Vooral de greens laten veel schade zien

UV frequency metrology on CO (a3Pi); isotope effects and sensitivity to a variation of the proton-to-electron mass ratio

UV frequency metrology has been performed on the a3Pi - X1Sigma+ (0,0) band of various isotopologues of CO using a frequency-quadrupled injection-seeded narrow-band pulsed Titanium:Sapphire laser referenced to a frequency comb laser. The band origin is determined with an accuracy of 5 MHz (delta \nu / \nu = 3 * 10^-9), while the energy differences between rotational levels in the a3Pi state are determined with an accuracy of 500 kHz. From these measurements, in combination with previously published radiofrequency and microwave data, a new set of molecular constants is obtained that describes the level structure of the a3Pi state of 12C16O and 13C16O with improved accuracy. Transitions in the different isotopologues are well reproduced by scaling the molecular constants of 12C16O via the common mass-scaling rules. Only the value of the band origin could not be scaled, indicative of a breakdown of the Born-Oppenheimer approximation. Our analysis confirms the extreme sensitivity of two-photon microwave transitions between nearly-degenerate rotational levels of different Omega-manifolds for probing a possible variation of the proton-to-electron mass ratio, \mu=m_p/m_e, on a laboratory time scale

Line tensions, correlation lengths, and critical exponents in lipid membranes near critical points

Membranes containing a wide variety of ternary mixtures of high chain-melting temperature lipids, low chain-melting temperature lipids, and cholesterol undergo lateral phase separartion into coexisting liquid phases at a miscibility transition. When membranes are prepared from a ternary lipid mixture at a critical composition, they pass through a miscibility critical point at the transition temperature. Since the critical temperature is typically on the order of room temperature, membranes provide an unusual opportunity in which to perform a quantitative study of biophysical systems that exhibit critical phenomena in the two-dimensional Ising universality class. As a critical point is approached from either high or low temperature, the scale of fluctuations in lipid composition, set by the correlation length, diverges. In addition, as a critical point is approached from low temperature, the line tension between coexisting phases decreases to zero. Here we quantitatively evaluate the temperature dependence of line tension between liquid domains and of fluctuation correlation lengths in lipid membranes in order to extract a critical exponent, nu. We obtain nu=1.2 plus or minus 0.2, consistent with the Ising model prediction nu=1. We also evaluate the probability distributions of pixel intensities in fluoresence images of membranes. From the temperature dependence of these distributions above the critical temperature, we extract an independent critical exponent beta=0.124 plus or minus 0.03 which is consistent with the Ising prediction of beta=1/8.Comment: 22 pages, 7 figure