2,635 research outputs found
Low-field microwave absorption in epitaxial La-Sr-Mn-O films resulting from the angle-tuned ferromagnetic resonance in the multidomain state
We studied magnetic-field induced microwave absorption in 100-200 nm thick
LaSrMnO films on SrTiO substrate and found a
low-field absorption with a very peculiar angular dependence: it appears only
in the oblique field and is absent both in the parallel and in the
perpendicular orientations. We demonstrate that this low-field absorption
results from the ferromagnetic resonance in the multidomain state (domain-mode
resonance). Its unusual angular dependence arises from the interplay between
the parallel component of the magnetic field that drives the film into
multidomain state and the perpendicular field component that controls the
domain width through its effect on domain wall energy. The low-field microwave
absorption in the multidomain state can be a tool to probe domain structure in
magnetic films with in-plane magnetization.Comment: 9 pages, 9 Figure
BaCu3O4: High Temperature Magnetic Order in One-Dimensional S=1/2 Diamond-Chains
The magnetic properties of the alkaline earth oxocuprate BaCu3O4 are
investigated. We show that the characteristic Cu3O4 layers of this material can
be described with diamond chains of antiferromagnetically coupled Cu 1/2 spins
with only a weak coupling between two adjacent chains. These Cu3O4 layers seem
to represent a so far unique system of weakly coupled one-dimensional magnetic
objects where the local AF ordering of the Cu2+ ions leads to an actual net
magnetic moment of an isolated diamond chain. We demonstrate a magnetic
transition at a high N\'eel temperature T_{N}=336 K
Spin wave resonances in La_{0.7}Sr_{0.3}MnO_{3} films: measurement of spin wave stiffness and anisotropy field
We studied magnetic field dependent microwave absorption in epitaxial
LaSrMnO films using an X-band Bruker ESR spectrometer. By
analyzing angular and temperature dependence of the ferromagnetic and spin-wave
resonances we determine spin-wave stiffness and anisotropy field. The spin-wave
stiffness as found from the spectrum of the standing spin-wave resonances in
thin films is in fair agreement with the results of inelastic neutron
scattering studies on a single crystal of the same composition [Vasiliu-Doloc
et al., J. Appl. Phys. \textbf{83}, 7343 (1998)].Comment: 15 pages, 7 figures (now figure captions are included
Nonresonant microwave absorption in epitaxial La-Sr-Mn-O films and its relation to colossal magnetoresistance
We study magnetic-field-dependent nonresonant microwave absorption and
dispersion in thin LaSrMnO films and show that it
originates from the colossal magnetoresistance. We develop the model for
magnetoresistance of a thin ferromagnetic film in oblique magnetic field. The
model accounts fairly well for our experimental findings, as well as for
results of other researchers. We demonstrate that nonresonant microwave
absorption is a powerful technique that allows contactless measurement of
magnetic properties of thin films, including magnetoresistance, anisotropy
field and coercive field.Comment: 20 pages, 11 figure
Draft Genome Sequence of the Principal Etiological Agent of Farmer?s Lung Disease, Saccharopolyspora rectivirgula
Saccharopolyspora rectivirgula is the main cause of farmer's lung disease. The development of recombinant antigens to standardize the serodiagnosis of the disease requires knowledge of the S. rectivirgula genome. We sequenced the genome of an environmental strain, S. rectivirgula DSM 43113. A total of 3,221 proteins were found to be encoded in a short 3.9-Mb genome
Statistical inference of the generation probability of T-cell receptors from sequence repertoires
Stochastic rearrangement of germline DNA by VDJ recombination is at the
origin of immune system diversity. This process is implemented via a series of
stochastic molecular events involving gene choices and random nucleotide
insertions between, and deletions from, genes. We use large sequence
repertoires of the variable CDR3 region of human CD4+ T-cell receptor beta
chains to infer the statistical properties of these basic biochemical events.
Since any given CDR3 sequence can be produced in multiple ways, the probability
distribution of hidden recombination events cannot be inferred directly from
the observed sequences; we therefore develop a maximum likelihood inference
method to achieve this end. To separate the properties of the molecular
rearrangement mechanism from the effects of selection, we focus on
non-productive CDR3 sequences in T-cell DNA. We infer the joint distribution of
the various generative events that occur when a new T-cell receptor gene is
created. We find a rich picture of correlation (and absence thereof), providing
insight into the molecular mechanisms involved. The generative event statistics
are consistent between individuals, suggesting a universal biochemical process.
Our distribution predicts the generation probability of any specific CDR3
sequence by the primitive recombination process, allowing us to quantify the
potential diversity of the T-cell repertoire and to understand why some
sequences are shared between individuals. We argue that the use of formal
statistical inference methods, of the kind presented in this paper, will be
essential for quantitative understanding of the generation and evolution of
diversity in the adaptive immune system.Comment: 20 pages, including Appendi
A Marriage of Old and New: Chemostats and Microarrays Identify a New Model System for Ammonium Toxicity
Toxicity is related to an organism's ability to rid itself of the offending molecules. This primer provides insights into how this can be monitored by highlighting the case of ammonium toxicity
Performance of a brief geriatric evaluation compared to a comprehensive geriatric assessment for detection of geriatric syndromes in family medicine: a prospective diagnostic study.
Geriatric syndromes are rarely detected in family medicine. Within the AGE program (active geriatric evaluation), a brief assessment tool (BAT) designed for family physicians (FP) was developed and its diagnostic performance estimated by comparison to a comprehensive geriatric assessment.
This prospective diagnostic study was conducted in four primary care sites in Switzerland. Participants were aged at least 70 years and attending a routine appointment with their physician, without previous documented geriatric assessment. Participants were assessed by their family physicians using the BAT, and by a geriatriciant who performed a comprehensive geriatric assessment within the following two-month period (reference standard). Both the BAT and the full assessment targeted eight geriatric syndromes: cognitive impairment, mood impairment, urinary incontinence, visual impairment, hearing loss, undernutrition, osteoporosis and gait and balance impairment. Diagnostic accuracy of the BAT was estimated in terms of sensitivity, specificity, and predictive values; secondary outcomes were measures of feasibility, in terms of added consultation time and comprehensiveness in applying the BAT items.
Prevalence of the geriatric syndromes in participants (N=85, 46 (54.1%) women, mean age 78 years (SD 6))ranged from 30.0% (malnutrition and cognitive impairment) to 71.0% (visual impairment), with a median number of 3 syndromes (IQR 2 to 4) per participant. Sensitivity of the BAT ranged from 25.0% for undernutrition (95%CI 9.8% - 46.7%) to 82.1% for hearing impairment (95%CI 66.5% - 92.5%), while specificity ranged from 45.8% for visual impairment (95%CI 25.6-67.2) to 87.7% for undernutrition (76.3% to 94.9%). Finally, most negative predictive values (NPV) were between 73.5% and 84.1%, excluding visual impairment with a NPV of 50.0%. Family physicians reported BAT use as per instructions for 76.7% of the syndromes assessed.
Although the BAT does not replace a comprehensive geriatric assessment, it is a useful and appropriate tool for the FP to screen elderly patients for most geriatric syndromes.
The study was registered on ClinicalTrials.gov on February 20, 2013 ( NCT01816087 )
- …