5,939 research outputs found
Unifying Magnons and Triplons in Stripe-Ordered Cuprate Superconductors
Based on a two-dimensional model of coupled two-leg spin ladders, we derive a
unified picture of recent neutron scattering data of stripe-ordered
La_(15/8)Ba_(1/8)CuO_4, namely of the low-energy magnons around the
superstructure satellites and of the triplon excitations at higher energies.
The resonance peak at the antiferromagnetic wave vector Q_AF in the
stripe-ordered phase corresponds to a saddle point in the dispersion of the
magnetic excitations. Quantitative agreement with the neutron data is obtained
for J= 130-160 meV and J_cyc/J = 0.2-0.25.Comment: 4 pages, 4 figures included updated version taking new data into
account; factor in spectral weight corrected; Figs. 2 and 4 change
Reduction of Coxiella burnetii prevalence by vaccination of goats and sheep, the Netherlands
Recently, the number of human Q fever cases in the Netherlands increased dramatically. In response to this increase, dairy goats and dairy sheep were vaccinated against Coxiella burnetii. All pregnant dairy goats and dairy sheep in herds positive for Q fever were culled. We identified the effect of vaccination on bacterial shedding by small ruminants. On the day of culling, samples of uterine fluid, vaginal mucus, and milk were obtained from 957 pregnant animals in 13 herds. Prevalence and bacterial load were reduced in vaccinated animals compared with unvaccinated animals. These effects were most pronounced in animals during their first pregnancy. Results indicate that vaccination may reduce bacterial load in the environment and human exposure to C. burnetii
NMR evidence for two-step phase-separation in Nd_{1.85}Ce_{0.15}CuO_{4-delta}
By Cu NMR we studied the spin and charge structure in
Nd_{2-x}Ce_{x}CuO_{4-delta}. For x=0.15, starting from a superconducting
sample, the low temperature magnetic order in the sample reoxygenated under 1
bar oxygen at 900^0 C, reveals a peculiar modulation of the internal field,
indicative for a phase characterized by large charge droplets ('Blob'-phase).
By prolonged reoxygenation at 4 bar the blobs brake up and the spin structure
changes to that of an ordered antiferromagnet (AF). We conclude that the
superconductivity in the n-type systems competes with a genuine type I
Mott-insulating state
Polarization-Based Illumination Detection for Coherent Augmented Reality Scene Rendering in Dynamic Environments
A virtual object that is integrated into the real world in a perceptually coherent manner using the physical illumination information in the current environment is still under development. Several researchers investigated the problem producing a high-quality result; however, pre-computation and offline availability of resources were the essential assumption upon which the system relied. In this paper, we propose a novel and robust approach to identifying the incident light in the scene using the polarization properties of the light wave and using this information to produce a visually coherent augmented reality within a dynamic environment. This approach is part of a complete system which has three simultaneous components that run in real-time: (i) the detection of the incident light angle, (ii) the estimation of the reflected light, and (iii) the creation of the shading properties which are required to provide any virtual object with the detected lighting, reflected shadows, and adequate materials. Finally, the system performance is analyzed where our approach has reduced the overall computational cost
Density of states and magnetoconductance of disordered Au point contacts
We report the first low temperature magnetotransport measurements on
electrochemically fabricated atomic scale gold nanojunctions. As , the
junctions exhibit nonperturbatively large zero bias anomalies (ZBAs) in their
differential conductance. We consider several explanations and find that the
ZBAs are consistent with a reduced local density of states (LDOS) in the
disordered metal. We suggest that this is a result of Coulomb interactions in a
granular metal with moderate intergrain coupling. Magnetoconductance of atomic
scale junctions also differs significantly from that of less geometrically
constrained devices, and supports this explanation.Comment: 5 pages, 5 figures. Accepted to PRB as Brief Repor
Giant enhancement of photodissociation of polar dimers in electric fields
We explore the photodissociation of polar dimers in static electric fields in
the cold regime using the example of the LiCs molecule. A giant enhancement of
the differential cross section is found for laboratory electric field
strengths, and analyzed with varying rovibrational bound states, continuum
energies as well as field strengths.Comment: 6 pages, 6 figure
Experiences and needs of patients with incurable cancer regarding advance care planning:results from a national cross-sectional survey
Introduction: Patients faced with incurable cancer may experience a lack of support from their physician throughout and after treatment. Studies on the needs and experiences of these patients are scarce. In this study, we explored the needs and experiences of patients diagnosed with incurable cancer regarding the conversation, in which they were told that their cancer was incurable, the care received after this conversation, and their preferences regarding end-of-life conversations. Methods: Data were cross-sectionally collected through a national online survey in the Netherlands (September 2018). Descriptive statistics and correlation coefficients were reported and subgroups were compared. Results: Six hundred fifty-four patients (mean age 60Â years; 58% women) completed the survey. Patients were primarily diagnosed with breast cancer (22%) or a hematological malignancy (21%). Patients reported a strong need for emotional support during the conversation, in which they were told their cancer was incurable (mean score 8.3; scale 1â10). Their experienced satisfaction with received emotional support was mediocre (mean score 6.4; scale 1â10). Of those patients who felt like they did not receive any additional care (37%) after the diagnosis, the majority expressed a clear need for this kind of care (59%). Mostly, support pertained to psychosocial issues. Regarding conversations about the end of life, most patients (62%) expressed a need to discuss this topic, and preferred their healthcare provider to initiate this conversation. Conclusion: Care for patients with incurable cancer can be further improved by tailoring conversations to specific needs and timely providing appropriate supportive care services
Conduction channels of superconducting quantum point contacts
Atomic quantum point contacts accommodate a small number of conduction
channels. Their number N and transmission coefficients {T_n} can be determined
by analyzing the subgap structure due to multiple Andreev reflections in the
current-voltage (IV) characteristics in the superconducting state. With the
help of mechanically controllable break-junctions we have produced Al contacts
consisting of a small number of atoms. In the smallest stable contacts, usually
three channels contribute to the transport. We show here that the channel
ensemble {T_n} of few atom contacts remains unchanged up to temperatures and
magnetic fields approaching the critical temperature and the critical field,
respectively, giving experimental evidence for the prediction that the
conduction channels are the same in the normal and in the superconducting
state.Comment: 8 pages, 5 .eps figures. To be published in Physica B 22
First time determination of the microscopic structure of a stripe phase: Low temperature NMR in La2NiO4.17
The experimental observations of stripes in superconducting cuprates and
insulating nickelates clearly show the modulation in charge and spin density.
However, these have proven to be rather insensitive to the harmonic structure
and (site or bond) ordering. Using 139La NMR in La2NiO4.17, we show that in the
1/3 hole doped nickelate below the freezing temperature the stripes are
strongly solitonic and site ordered with Ni3+ ions carrying S=1/2 in the domain
walls and Ni2+ ions with S=1 in the domains.Comment: 4 pages including 4 figure
Shot noise suppression at room temperature in atomic-scale Au junctions
Shot noise encodes additional information not directly inferable from simple
electronic transport measurements. Previous measurements in atomic-scale metal
junctions at cryogenic temperatures have shown suppression of the shot noise at
particular conductance values. This suppression demonstrates that transport in
these structures proceeds via discrete quantum channels. Using a high frequency
technique, we simultaneously acquire noise data and conductance histograms in
Au junctions at room temperature and ambient conditions. We observe noise
suppression at up to three conductance quanta, with possible indications of
current-induced local heating and noise in the contact region at high
biases. These measurements demonstrate the quantum character of transport at
room temperature at the atomic scale. This technique provides an additional
tool for studying dissipation and correlations in nanodevices.Comment: 15 pages, 4 figures + supporting information (6 pages, 6 figures
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