1,160 research outputs found
Cavity Optomechanical Magnetometer
A cavity optomechanical magnetometer is demonstrated where the magnetic field
induced expansion of a magnetostrictive material is transduced onto the
physical structure of a highly compliant optical microresonator. The resulting
motion is read out optically with ultra-high sensitivity. Detecting the
magnetostrictive deformation of Terfenol-D with a toroidal whispering gallery
mode (TWGM) resonator a peak sensitivity of 400 nT/Hz^.5 was achieved with
theoretical modelling predicting that sensitivities of up to 500 fT/Hz^.5 may
be possible. This chip-based magnetometer combines high-sensitivity and large
dynamic range with small size and room temperature operation
Model of a microtoroidal magnetometer
We present a model of a cavity optomechanical magnetic field sensor based on a microtoroidal resonator. The magnetic field induced expansion of a magnetostrictive material is transduced onto the physical structure of a highly compliant optical microresonator. The resulting motion is read out optically with ultra-high sensitivity. According to our theoretical model sensitivities of up to 750 fT/√ Hz may be possible. The simultaneous presence of high-quality mechanical and optical resonances in microtoroids greatly enhances both the response to the magnetic field and the measurement sensitivity
In-trap conversion electron spectroscopy
The Penning trap REXTRAP at ISOLDE was used to test the feasibility of in-trap conversion electron spectroscopy. The results of simulations, experiments with solid conversion electron sources as well as first on-line and tests with trapped radioactive ions are presented. In addition to obtaining high-resolution spectroscopic data, the detection of conversion electrons was found to be a useful tool for the diagnostics of the trap operation. The tests proved the feasibility of in-trap spectroscopy but also revealed some potential problems to be addressed in the future
Sensitivity of cavity optomechanical field sensors
This article presents a technique for modeling cavity optomechanical field sensors. A magnetic or electric field induces a spatially varying strain across the sensor. The effect of this strain is accounted for by separating the mechanical motion of the sensor into eigenmodes, each modeled by a simple harmonic oscillator. The force induced on each oscillator can then be determined from an overlap integral between strain and the corresponding eigenmode, with the optomechanical coupling strength determining the ultimate resolution with which this force can be detected
Genome-wide association study of borderline personality disorder reveals genetic overlap with bipolar disorder, major depression and schizophrenia
Borderline personality disorder (BOR) is determined by environmental and
genetic factors, and characterized by affective instability and impulsivity,
diagnostic symptoms also observed in manic phases of bipolar disorder (BIP).
Up to 20% of BIP patients show comorbidity with BOR. This report describes the
first case–control genome-wide association study (GWAS) of BOR, performed in
one of the largest BOR patient samples worldwide. The focus of our analysis
was (i) to detect genes and gene sets involved in BOR and (ii) to investigate
the genetic overlap with BIP. As there is considerable genetic overlap between
BIP, major depression (MDD) and schizophrenia (SCZ) and a high comorbidity of
BOR and MDD, we also analyzed the genetic overlap of BOR with SCZ and MDD.
GWAS, gene-based tests and gene-set analyses were performed in 998 BOR
patients and 1545 controls. Linkage disequilibrium score regression was used
to detect the genetic overlap between BOR and these disorders. Single marker
analysis revealed no significant association after correction for multiple
testing. Gene-based analysis yielded two significant genes: DPYD (P=4.42 ×
10−7) and PKP4 (P=8.67 × 10−7); and gene-set analysis yielded a significant
finding for exocytosis (GO:0006887, PFDR=0.019; FDR, false discovery rate).
Prior studies have implicated DPYD, PKP4 and exocytosis in BIP and SCZ. The
most notable finding of the present study was the genetic overlap of BOR with
BIP (rg=0.28 [P=2.99 × 10−3]), SCZ (rg=0.34 [P=4.37 × 10−5]) and MDD (rg=0.57
[P=1.04 × 10−3]). We believe our study is the first to demonstrate that BOR
overlaps with BIP, MDD and SCZ on the genetic level. Whether this is confined
to transdiagnostic clinical symptoms should be examined in future studies
MRI of female genital tract congenital anomalies: European Society of Urogenital Radiology (ESUR) guidelines
OBJECTIVE: To develop imaging guidelines for the MR work-up of female genital tract congenital anomalies (FGTCA). METHODS: These guidelines were prepared based on a questionnaire sent to all members of the European Society of Urogenital Radiology (ESUR) Female Pelvic Imaging Working Group (FPI-WG), critical review of the literature and expert consensus decision. RESULTS: The returned questionnaires from 17 different institutions have shown reasonable homogeneity of practice. Recommendations with focus on patient preparation and MR protocol are proposed, as these are key to optimised examinations. Details on MR sequences and planning of uterus-orientated sequences are provided. CONCLUSIONS: The multiplanar capabilities and soft tissue resolution of MRI provide superb characterisation of the wide spectrum of findings in FGTCA. A standardised imaging protocol and method of reporting ensures that the salient features are recognised, contributing to a correct diagnosis and classification of FGTCA, associated anomalies and complications. These imaging guidelines are based on current practice among expert radiologists in the field and incorporate up to date information regarding MR protocols and essentials of recently published classification systems. KEY POINTS: * MRI allows comprehensive evaluation of female genital tract congenital anomalies, in a single examination. * A dedicated MRI protocol comprises uterus-orientated sequences and vaginal and renal evaluation. * Integration of classification systems and structured reporting helps in successful communication of the imaging findings
Curvature-coupling dependence of membrane protein diffusion coefficients
We consider the lateral diffusion of a protein interacting with the curvature
of the membrane. The interaction energy is minimized if the particle is at a
membrane position with a certain curvature that agrees with the spontaneous
curvature of the particle. We employ stochastic simulations that take into
account both the thermal fluctuations of the membrane and the diffusive
behavior of the particle. In this study we neglect the influence of the
particle on the membrane dynamics, thus the membrane dynamics agrees with that
of a freely fluctuating membrane. Overall, we find that this curvature-coupling
substantially enhances the diffusion coefficient. We compare the ratio of the
projected or measured diffusion coefficient and the free intramembrane
diffusion coefficient, which is a parameter of the simulations, with analytical
results that rely on several approximations. We find that the simulations
always lead to a somewhat smaller diffusion coefficient than our analytical
approach. A detailed study of the correlations of the forces acting on the
particle indicates that the diffusing inclusion tries to follow favorable
positions on the membrane, such that forces along the trajectory are on average
smaller than they would be for random particle positions.Comment: 16 pages, 8 figure
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