Compression of sub-relativistic space-charge-dominated electron bunches for single-shot femtosecond electron diffraction

We demonstrate compression of 95 keV, space-charge-dominated electron bunches to sub-100 fs durations. These bunches have sufficient charge (200 fC) and are of sufficient quality to capture a diffraction pattern with a single shot, which we demonstrate by a diffraction experiment on a polycrystalline gold foil. Compression is realized by means of velocity bunching as a result of a velocity chirp, induced by the oscillatory longitudinal electric field of a 3 GHz radio-frequency cavity. The arrival time jitter is measured to be 80 fs

THREE MAIN SPATIAL TECHNIQUES of SPATIAL MIXING SYSTEM

This written review is to have a deep review for three techniques to realize spatial effects, which are Head Related Transfer Functions, Image Source Method, and Schroeder Reverberation, utilized in Spatial Mixing System, 2nd lab report.Architecture & Allied Art

Higher Mediterranean Diet scores are not cross-sectionally associated with better cognitive scores in 20- to 70-year-old Dutch adults: The NQplus study

Adherence to the Mediterranean Diet (MedDiet) has been suggested to reduce the risk of age-related cognitive decline. Therefore, we hypothesized that adults consuming a more Mediterranean-like diet were more likely to have better cognitive scores. We investigated cross-sectional associations between MedDiet adherence and cognitive performance using data of 1607 Dutch men and women aged 20–70 years. Dietary intake was assessed using a 183-item Food Frequency Questionnaire. MedDiet adherence was defined by a 0–9 pointscale; which was based on intakes of vegetables, legumes, fruits/nuts, cereals, fish/seafood, meat/poultry, dairy, ethanol and the MUFA:SFA ratio. Cognitive function was assessed with a neuropsychological test battery. Linear regression analyses adjusted for relevant covariates showed a significant inverse association between MedDiet adherence and everyday memory: specifically β = −0.107 ± 0.046 points (P = .02) for the total population and β = −0.139 ± 0.055 points (P = .01) for those aged ≥50 years. Further exploration of the individual MedDiet food groups suggested that the association between MedDiet and everyday memory was predominantly driven by the MUFA:SFA ratio. Moreover, associations were observed between higher ethanol intake better semantic memory and language production (β = 0.016 ± 0.008 P = .05), higher vegetable intake with better processing speed (β = 0.005 ± 0.002, P = .02), and higher legumes intake with poorer processing speed (β = −0.014 ±0.006, P = 03). Thus, in this Dutch cohort, higher MedDiet adherence was associated with poorer everyday memory

Voorstel voor een co-existentie monitoringsprogramma t.b.v. het naast elkaar bestaan van genetisch gemodificeerde (GG) en niet GG-teelten in toekomstige praktijksituaties. 1. Maïs

In het rapport wordt een voorstel voor een concreet co-existentiemonitoringprogramma (CMP) voor maïs beschreven dat is aangepast aan de specifieke gewaseigenschappen van maïs. De gemaakte keuzen t.b.v. een pragmatische invulling van het voorgestelde CMP worden in de opvolgende hoofdstukken toegelicht op basis van de huidige stand van zaken in het wetenschappelijk onderzoek aan (trans)genverspreiding in maïs. Er is nog beperkte ervaring met een CMP in maïs, bijvoorbeeld in Portugal, Tsjechië en Slowakije waar Bt MON810 maïs op beperkte schaal verbouwd wordt. Er is ook geen (Europese) standaard voor een CMP, maar er is wel voor maïs als eerste een Best Practice Document door het European Co-existence Bureau (ECoB) van het JRC uitgebracht (Rizov & Rodríguez-Cerezo 2014)

Gastric cancers of Western European and African patients show different patterns of genomic instability

<p>Abstract</p> <p>Background</p> <p>Infection with <it>H. pylori </it>is important in the etiology of gastric cancer. Gastric cancer is infrequent in Africa, despite high frequencies of <it>H. pylori </it>infection, referred to as the African enigma. Variation in environmental and host factors influencing gastric cancer risk between different populations have been reported but little is known about the biological differences between gastric cancers from different geographic locations. We aim to study genomic instability patterns of gastric cancers obtained from patients from United Kingdom (UK) and South Africa (SA), in an attempt to support the African enigma hypothesis at the biological level.</p> <p>Methods</p> <p>DNA was isolated from 67 gastric adenocarcinomas, 33 UK patients, 9 Caucasian SA patients and 25 native SA patients. Microsatellite instability and chromosomal instability were analyzed by PCR and microarray comparative genomic hybridization, respectively. Data was analyzed by supervised univariate and multivariate analyses as well as unsupervised hierarchical cluster analysis.</p> <p>Results</p> <p>Tumors from Caucasian and native SA patients showed significantly more microsatellite instable tumors (p < 0.05). For the microsatellite stable tumors, geographical origin of the patients correlated with cluster membership, derived from unsupervised hierarchical cluster analysis (p = 0.001). Several chromosomal alterations showed significantly different frequencies in tumors from UK patients and native SA patients, but not between UK and Caucasian SA patients and between native and Caucasian SA patients.</p> <p>Conclusions</p> <p>Gastric cancers from SA and UK patients show differences in genetic instability patterns, indicating possible different biological mechanisms in patients from different geographical origin. This is of future clinical relevance for stratification of gastric cancer therapy.</p

Tunable few-electron double quantum dots and Klein tunnelling in ultra-clean carbon nanotubes

Quantum dots defined in carbon nanotubes are a platform for both basic scientific studies and research into new device applications. In particular, they have unique properties that make them attractive for studying the coherent properties of single electron spins. To perform such experiments it is necessary to confine a single electron in a quantum dot with highly tunable barriers, but disorder has until now prevented tunable nanotube-based quantum-dot devices from reaching the single-electron regime. Here, we use local gate voltages applied to an ultra-clean suspended nanotube to confine a single electron in both a single quantum dot and, for the first time, in a tunable double quantum dot. This tunability is limited by a novel type of tunnelling that is analogous to that in the Klein paradox of relativistic quantum mechanics.Comment: 21 pages including supplementary informatio

Spin Exciton in quantum dot with spin orbit coupling in high magnetic field

Coulomb interactions of few ($N$) electrons confined in a disk shaped quantum dot, with a large magnetic field $B=B^*$ applied in the z-direction (orthogonal to the dot), produce a fully spin polarized ground state. We numerically study the splitting of the levels corresponding to the multiplet of total spin $S=N/2$ (each labeled by a different total angular momentum $J_z$) in presence of an electric field parallel to $B$, coupled to $S$ by a Rashba term. We find that the first excited state is a spin exciton with a reversed spin at the origin. This is reminiscent of the Quantum Hall Ferromagnet at filling one which has the skyrmion-like state as its first excited state. The spin exciton level can be tuned with the electric field and infrared radiation can provide energy and angular momentum to excite it.Comment: 9 pages, 9 figures. submitted to Phys.Rev.

Spectral function of the Kondo model in high magnetic fields

Using a recently developed perturbative renormalization group (RG) scheme, we calculate analytically the spectral function of a Kondo impurity for either large frequencies w or large magnetic field B and arbitrary frequencies. For large w >> max[B,T_K] the spectral function decays as 1/ln^2[ w/T_K ] with prefactors which depend on the magnetization. The spin-resolved spectral function displays a pronounced peak at w=B with a characteristic asymmetry. In a detailed comparison with results from numerical renormalization group (NRG) and bare perturbation theory in next-to-leading logarithmic order, we show that our perturbative RG scheme is controlled by the small parameter 1/ln[ max(w,B)/T_K]. Furthermore, we assess the ability of the NRG to resolve structures at finite frequencies.Comment: 8 pages, version published in PRB, minor change