717 research outputs found
Radio-frequency driven dipole-dipole interactions in spatially separated volumes
Radio-frequency (rf) fields in the MHz range are used to induce resonant
energy transfer between cold Rydberg atoms in spatially separated volumes.
After laser preparation of the Rydberg atoms, dipole-dipole coupling excites
the 49s atoms in one cylinder to the 49p state while the 41d atoms in the
second cylinder are transferred down to the 42p state. The energy exchanged
between the atoms in this process is 33 GHz. An external rf-field brings this
energy transfer into resonance. The strength of the interaction has been
investigated as a function of amplitude (0-1 V/cm) and frequency (1-30 MHz) of
the rf-field and as a function of a static field offset. Multi-photon
transitions up to fifth order as well as selection rules prohibiting the
process at certain fields have been observed. The width of the resonances has
been reduced compared to earlier results by switching off external magnetic
fields of the magneto-optical trap, making sub-MHz spectroscopy possible. All
features are well reproduced by theoretical calculations taking the strong
ac-Stark shift due to the rf-field into account
Factoid Forensics: Have âmore than 40â Australian families abandoned their homes because of wind farm noise?
Background Anti wind farm activists repeatedly claim that families said to be adversely affected by noise from wind turbines âabandonâ their homes. In Australia, a claim of âmore than 40 familiesâ has been made by a prominent anti wind farm activist. Methods Six sources (parliamentary submissions, media reports, an anti wind farm website, wind industry sources, correspondence with known anti wind farm activists, and with three politicians opposed to wind farms) were used to find evidence of home âabandonmentsâ. Results Claims about 12 Australian households permanently (n=10) or periodically (n=2) leaving their homes were found. However, no house appears to have been permanently âabandonedâ without sale, as the expression implies. These 12 cases need contextualizing against considerations that several of those involved were either dedicated activists against wind farms from times sometimes pre-dating their construction, were engaged in protracted negotiations for home purchase with wind companies, had pre-existing health problems, grievances with the wind company over employment or had left the area for unrelated reasons of employment elsewhere. Conclusions The statement that âmore than 40â houses have been âabandonedâ because of wind turbines in Australia is a factoid promoted by wind farm opponents for dramatic, rhetorical impact. Other considerations are often involved in abandonment unrelated to the claims made about wind farm noise
Numerical study of two-body correlation in a 1D lattice with perfect blockade
We compute the dynamics of excitation and two-body correlation for two-level
"pseudoatoms" in a 1D lattice. We adopt a simplified model where pair
excitation within a finite range is perfectly blocked. Each superatom is
initially in the ground state, and then subjected to an external driving laser
with Rabi frequency satisfying a Poissonian distribution, mimicking the
scenario as in Rydberg gases. We find that two-body quantum correlation drops
very fast with the distance between pseudoatoms. However, the total correlation
decays slowly even at large distance. Our results may be useful to the
understanding of Rydberg gases in the strong blockade regime
Visualization of neural activity of forager honeybee brain by IEGs
We assessed bone mineral density (BMD) and body composition in children with Noonan's syndrome (NS) before and during growth hormone (GH) treatment. Sixteen children (12 boys, 4 girls) with NS aged 5.8-14.2 (mean 10.0) years were studied for 2 years. Anthropometry, BMD measurements by radiographic absorptiometry and bioimpedance measurements (Akern-BIA 101/S) were performed at baseline and after 3, 6, 12 and 24 months. Daily GH dosage was 0.05 mg/kg. Trabecular volumetric BMD was normal; cortical BMD was in the lower normal range at baseline and slightly increased over the 2 years. Fat free mass and total body water were below normal at the start and increased significantly over the first 3 months, with a slight increment thereafter. Percentage fat mass decreased over the first 6 months and increased thereafter. These findings are comparable to the data on body composition in short normal children and girls with Turner's syndrome treated with GH
Telomere length and metabolic syndrome traits: a Mendelian randomisation study
Observational studies have revealed associations between short leucocyte telomere length (LTL), a TL marker in somatic tissues and multiple Metabolic Syndrome (MetS) traits. Animal studies have supported these findings by showing that increased telomere attrition leads to adipose tissue dysfunction and insulin resistance. We investigated the associations between genetically instrumented LTL and MetS traits using Mendelian Randomisation (MR). Fifty-two independent variants identified at FDR<0.05 from a genome-wide association study (GWAS) including 78,592 Europeans and collectively accounting for 2.93% of LTL variance were selected as genetic instruments for LTL. Summary-level data for MetS traits and for the MetS as a binary phenotype were obtained from the largest publicly available GWAS and two-sample MR analyses were used to estimate the associations of LTL with these traits. The combined effect of the genetic instruments was modelled using inverse variance weighted regression and sensitivity analyses with MR-Egger, weighted-median and MR-PRESSO were performed to test for and correct horizonal pleiotropy. Genetically instrumented longer LTL was associated with higher waist-to-hip ratio adjusted for body mass index (beta = 0.045 SD, SE = 0.018, p = 0.01), raised systolic (beta = 1.529 mmHg, SE = 0.332, p = 4x10(-6)) and diastolic (beta = 0.633 mmHg, SE = 0.222, p = 0.004) blood pressure, and increased MetS risk (OR = 1.133, 95% CI 1.057-1.215). Consistent results were obtained in sensitivity analyses, which provided no evidence of unbalanced horizontal pleiotropy. Telomere shortening might not be a major driver of cellular senescence and dysfunction in human adipose tissue. Future experimental studies should examine the mechanistic bases for the links between longer LTL and increased upper-body fat distribution and raised blood pressure.Pathophysiology, epidemiology and therapy of agein
The effect of urbanization on ant abundance and diversity
The aim of the study was to evaluate the effect of continuous and discontinuous growth hormone treatment in Noonan's syndrome (NS) on linear growth and bone maturation. Thirty-seven children with NS aged between 5.4 and 17.5 y were treated with growth hormone (GH) in a dose of 0.15 IU kg)(-1) per day; 23 of these children were randomly assigned to one of 2 groups in a 3 y partly controlled prospective multicentre study. Group A (n = 8) immediately started GH treatment and after 2 y discontinued GH treatment for 1 y; group B (n = 15) served as a control group during the first year and started GH treatment after 1 y. After the 3 y study period, 17 out of the 23 children continued GH treatment. An additional 14 children (group C) were treated according to the same protocol, but without discontinuation of GH treatment. The effect of GH treatment for up to 3 y was evaluated in terms of gain in height standard deviation score (H-SDS) for calendar age and for bone age. Gain in H-SDS over the first year was significantly higher in the GH treatment group (+0.5) than in the non-treated group (+0.0); mean bone maturation was significantly faster in the GH treatment group (1.2 vs 0.5 y/y). Discontinuation in group A in the third study year resulted in catch-down growth (mean deltaH-SDS -0.2). Over 3 y of GH treatment, mean AH-SDS for calendar age was not significantly different between discontinuous (A: +0.8) and continuous treatment (B: +0.8; C: +1.2). Mean gain in H-SDS for bone age in the 3 groups (+0.2, 0.0. +0.3) was minimal after 3 y of GH treatment. CONCLUSION: This study confirmed the gain in H-SDS CA in Noonan's syndrome during long-term GH treatment. However, the accelerating effect of GH on bone maturation seemed to compromise the final height prognosis
Actief randenbeheer Drenthe lijkt effect te hebben
Via monitoring inzicht krijgen in het effect van actief randenbeheer op de oppervlaktewaterkwaliteit en de biodiversiteit in het landelijk gebied en op de inpasbaarheid op de agrarische bedrijven in een bepaald gebied. Dat was het doel van het pilotprogramma âActief Randenbeheer Drentheâ: een initiatief van de Provincie Drenthe, LTO-Noord en de waterschappen Hunze en Aaâs en Velt en Vecht, in het zuidoostelijk deel van Drenthe. Uitvoerende partijen zijn Royal Haskoning, Praktijkonderzoek Plant & Omgeving van Wageningen UR en enkele agrarische bedrijven. Het programma begon in januari 2006 en is in november 2008 afgesloten. De totale duur van de meetperiode bedroeg 27 maande
Health impact of nanotechnologies in food production
Geen RIVM rapportnummer in publicatieInventory study on the current use of nanotechnology in food products and advise on the most relevant safety evaluation issues. This report describes the results of this study. The report is set up in two parts. First you will find an aggregation of the results in the answer to 10 questions. In this part you will also find our suggestions for prioritizing the research that is needed. The second document is a scientific background document
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