Nanoscale Magnets Embedded in a Microstrip.

Nanoscale magnetic resonance imaging (NanoMRI) is an active area of applied research with potential applications in structural biology and quantum engineering. The success of this technological vision hinges on improving the instrument's sensitivity and functionality. A particular challenge is the optimization of the magnetic field gradient required for spatial encoding and of the radio frequency field used for spin control, in analogy to the components used in clinical MRI. In this work, we present the fabrication and characterization of a magnet-in-microstrip device that yields a compact form factor for both elements. We find that our design leads to a number of advantages, among them a 4-fold increase of the magnetic field gradient compared to those achieved with traditional fabrication methods. Our results can be useful for boosting the efficiency of a variety of different experimental arrangements and detection principles in the field of NanoMRI.

Soft-Clamped Silicon Nitride String Resonators at Millikelvin Temperatures.

We demonstrate that soft-clamped silicon nitride strings with a large aspect ratio can be operated at mK temperatures. The quality factors (Q) of two measured devices show consistent dependency on the cryostat temperature, with soft-clamped mechanical modes reaching Q>10^{9} at roughly 46 mK. For low optical readout power, Q is found to saturate, indicating good thermalization between the sample and the stage it is mounted on. Our best device exhibits a calculated force sensitivity of 9.6 zN/sqrt[Hz] and a thermal decoherence time of 0.38 s, which bode well for future applications such as nanomechanical force sensing.

Mid-infrared fiber-coupled photoacoustic sensor for biomedical applications.

Biomedical devices employed in therapy, diagnostics and for self-monitoring often require a high degree of flexibility and compactness. Many near infrared (NIR) optical fiber-coupled systems meet these requirements and are employed on a daily basis. However, mid-infrared (MIR) fibers-based systems have not yet found their way to routine application in medicine. In this work we present the implementation of the first MIR fiber-coupled photoacoustic sensor for the investigation of condensed samples in the MIR fingerprint region. The light of an external-cavity quantum-cascade laser (1010-1095 cm(-1)) is delivered by a silver halide fiber, which is attached to the PA cell. The PA chamber is conically shaped to perfectly match the beam escaping the fiber and to minimize the cell volume. This results in a compact and handy sensor for investigations of biological samples and the monitoring of constituents both in vitro and in vivo. The performance of the fiber-coupled PA sensor is demonstrated by sensing glucose in aqueous solutions. These measurements yield a detection limit of 57 mg/dL (SNR = 1). Furthermore, the fiber-coupled sensor has been applied to record human skin spectra at different body sites to illustrate its flexibility.

Different Levels of Context-Specificity of Teacher Self-Efficacy and Their Relations With Teaching Quality.

On the basis of Bandura's social cognitive theory, researchers often assume that a teachers' self-efficacy (TSE) will have a positive effect on teaching quality. However, the available empirical evidence is mixed. Building on previous research into TSE, we examined whether assessing class-/task-specific TSE gives a more accurate indication of the associations between TSE assessments and student-rated teaching quality. The analyses were based on the English sample of the Teaching and Learning International Survey (TALIS) Video Study. Mathematics teachers (N = 86) rated their self-efficacy beliefs using generalized task-specific TSE items and class-/task-specific TSE items. Their students (N = 1,930) rated the quality of teaching in their math class. Multilevel regression analyses revealed stronger associations between student-rated teaching quality and class-/task-specific TSE than generalized task-specific TSE. We discuss possible reasons for these results and outline the potential benefits of using class-specific assessments for future TSE research.

Remediation for Students With Mathematics Difficulties: An Intervention Study in Middle Schools.

As empirical studies have consistently shown, low achievement in mathematics at the secondary level can often be traced to deficits in the understanding of certain basic arithmetic concepts taught in primary school. The present intervention study in middle schools evaluated whether such learning deficits can be reduced effectively and whether the type of instruction influences students' progress. The sample consisted of 123 students in 34 classes, split among one control group and two intervention groups: (a) small group instruction and (b) independent work partially integrated into regular classrooms. Over a period of 14 weeks, students were taught basic concepts, such as place value and basic operations. In addition, they practiced fact retrieval and counting (in groups). Multilevel regression analyses demonstrated that the interventions can be used to reduce given deficits.