Atomic size oscillations in conductance histograms for gold nanowires and the influence of work hardening

Nanowires of different nature have been shown to self-assemble as a function of stress at the contact between two macroscopic metallic leads. Here we demonstrate for gold wires that the balance between various metastable nanowire configurations is influenced by the microstructure of the starting materials and we discover a new set of periodic structures, which we interpret as due to the atomic discreteness of the contact size for the three principal crystal orientations.Comment: This version corrects an error in attributing the three observed periods, and includes a comparison with recent model calculation

Dust, Ice and Gas in Time (DIGIT) Herschel program first results: A full PACS-SED scan of the gas line emission in protostar DK Cha

DK Cha is an intermediate-mass star in transition from an embedded configuration to a star plus disk stage. We aim to study the composition and energetics of the circumstellar material during this pivotal stage. Using the Range Scan mode of PACS on the Herschel Space Observatory, we obtained a spectrum of DK Cha from 55 to 210 micron as part of the DIGIT Key Program. Almost 50 molecular and atomic lines were detected, many more than the 7 lines detected in ISO-LWS. Nearly the entire ladder of CO from J=14-13 to 38-37 (E_u/k = 4080 K), water from levels as excited as E_u/k = 843 K, and OH lines up to E_u/k = 290 K were detected. The continuum emission in our PACS SED scan matches the flux expected from a model consisting of a star, a surrounding disk of 0.03 Solar mass, and an envelope of a similar mass, supporting the suggestion that the object is emerging from its main accretion stage. Molecular, atomic, and ionic emission lines in the far-infrared reveal the outflow's influence on the envelope. The inferred hot gas can be photon-heated, but some emission could be due to C-shocks in the walls of the outflow cavity.Comment: 4 Page letter, To appear in A&A special issue on Hersche

Radio-Frequency Spectroscopy of Ultracold Fermions

Radio-frequency techniques were used to study ultracold fermions. We observed the absence of mean-field "clock" shifts, the dominant source of systematic error in current atomic clocks based on bosonic atoms. This is a direct consequence of fermionic antisymmetry. Resonance shifts proportional to interaction strengths were observed in a three-level system. However, in the strongly interacting regime, these shifts became very small, reflecting the quantum unitarity limit and many-body effects. This insight into an interacting Fermi gas is relevant for the quest to observe superfluidity in this system.Comment: 6 pages, 6 figure

Inter-isotope determination of ultracold rubidium interactions from three high-precision experiments

Combining the measured binding energies of four of the most weakly bound rovibrational levels of the $^{87}$Rb$_2$ molecule with the results of two other recent high-precision rubidium experiments, we obtain exceptionally strong constraints on the atomic interaction parameters in a highly model independent analysis. The comparison of $^{85}$Rb and $^{87}$Rb data, where the two isotopes are related by a mass scaling procedure, plays a crucial role. Using the consistent picture of the interactions that thus arises we are led to predictions for scattering lengths, clock shifts, Feshbach resonance fields and widths with an unprecedented level of accuracy. To demonstrate this, we predict two Feshbach resonances in mixed-spin scattering channels at easily accessible magnetic field strengths, which we expect to play a role in the damping of coherent spin oscillations

Innovaties in de zorg voor ouderen

In deze 43-ste jaargang van het Tijdschrift voor Gerontologie en Geriatrie opent de redactie de nieuwe rubriek Recent onderzoek. Onderzoekers en programmaleiders van universitaire en niet-universitaire onderzoekscentra op het gebied van de gerontologie en geriatrie in België en Nederland zijn uitgenodigd om samenvattingen in te sturen van onderzoek dat onlangs door hen zelf of in hun vakgroepen of organisaties is afgerond. Met deze rubriek wil de redactie de lezers van het Tijdschrift blijven informeren over onderzoek naar veroudering en de maatschappelijke consequenties daarvan in brede zin: medisch, psychologisch en sociaal.  Het onderzoeksprogramma “Innovaties in de zorg voor ouderen” van de CAPHRI School for Public Health and Primary Care van de Universiteit Maastricht richt zich op drie samenhangende thema’s: (1) onderzoek naar prevalentie en determinanten van relevante zorgproblemen bij ouderen; (2) ontwikkeling en evaluatie van interventies en zorgvernieuwingen die zelfredzaamheid en kwaliteit van leven van ouderen (kunnen) bevorderen en (3) de implementatie van dergelijke interventies en zorgvernieuwingen in de zorgpraktijk. Hieronder volgen enkele voorbeelden van projecten die de afgelopen jaren binnen het programma zijn uitgevoerd

Spin-dependent transport in metal/semiconductor tunnel junctions

This paper describes a model as well as experiments on spin-polarized tunnelling with the aid of optical spin orientation. This involves tunnel junctions between a magnetic material and gallium arsenide (GaAs), where the latter is optically excited with circularly polarized light in order to generate spin-polarized carriers. A transport model is presented that takes account of carrier capture in the semiconductor surface states, and describes the semiconductor surface in terms of a spin-dependent energy distribution function. The so-called surface spin-splitting can be calculated from the balance of the polarized electron and hole flow in the semiconductor subsurface region, the polarized tunnelling current across the tunnel barrier between the magnetic material and the semiconductor surface, and the spin relaxation at the semiconductor surface. Measurements are presented of the circular-polarization-dependent photocurrent (the so-called helicity asymmetry) in thin-film tunnel junctions of Co/Al2O3/GaAs. In the absence of a tunnel barrier, the helicity asymmetry is caused by magneto-optical effects (magnetic circular dichroism). In the case where a tunnel barrier is present, the data cannot be explained by magneto-optical effects alone; the deviations provide evidence that spin-polarized tunnelling due to optical spin orientation occurs. In Co/τ-MnAl/AlAs/GaAs junctions no deviations from the magneto-optical effects are observed, most probably due to the weak spin polarization of τ-MnAl along the tunnelling direction; the latter is corroborated by bandstructure calculations. Finally, the application of photoexcited GaAs for spin-polarized tunnelling in a scanning tunnelling microscope is discussed.

Detection of NTRK Fusions and TRK Expression and Performance of pan-TRK Immunohistochemistry in Routine Diagnostics:Results from a Nationwide Community-Based Cohort

Gene fusions involving NTRK1, NTRK2, and NTRK3 are rare drivers of cancer that can be targeted with histology-agnostic inhibitors. This study aimed to determine the nationwide landscape of NTRK/TRK testing in the Netherlands and the usage of pan-TRK immunohistochemistry (IHC) as a preselection tool to detect NTRK fusions. All pathology reports in 2017–2020 containing the search term ‘TRK’ were retrieved from the Dutch Pathology Registry (PALGA). Patient characteristics, tumor histology, NTRK/TRK testing methods, and reported results were extracted. NTRK/TRK testing was reported for 7457 tumors. Absolute testing rates increased from 815 (2017) to 3380 (2020). Tumors were tested with DNA/RNA-based molecular assay(s) (48%), IHC (47%), or in combination (5%). A total of 69 fusions involving NTRK1 (n = 22), NTRK2 (n = 6) and NTRK3 (n = 41) were identified in tumors from adult (n = 51) and pediatric (n = 18) patients. In patients tested with both IHC and a molecular assay (n = 327, of which 29 NTRK fusion-positive), pan-TRK IHC had a sensitivity of 77% (95% confidence interval (CI), 56–91) and a specificity of 84% (95% CI, 78–88%). These results showed that pan-TRK IHC has a low sensitivity in current routine practice and warrants the introduction of quality guidelines regarding the implementation and interpretation of pan-TRK IHC

In-Brace versus Out-of-Brace Protocol for Radiographic Follow-Up of Patients with Idiopathic Scoliosis:A Retrospective Study

The purpose of this retrospective study was to compare two standardized protocols for radiological follow-up (in-brace versus out-of-brace radiographs) to study the rate of curve progression over time in surgically treated idiopathic scoliosis (IS) patients after failed brace treatment. In-brace radiographs have the advantage that proper fit of the brace and in-brace correction can be evaluated. However, detection of progression might theoretically be more difficult. Fifty-one IS patients that underwent surgical treatment after failed brace treatment were included. For 25 patients, follow-up radiographs were taken in-brace. For the other 26 patients, brace treatment was temporarily stopped before out-of-brace follow-up radiographs were taken. Both groups showed significant curve progression compared to baseline after a mean follow-up period of 3.4 years. The protocol with in-brace radiographs was noninferior regarding curve progression rate over time. The estimated monthly Cobb angle progression based on the mixed-effect model was 0.5 degrees in both groups. No interaction effect was found for time, and patients' baseline Cobb angle (p = 0.98), and for time and patients' initial in-brace correction (p = 0.32). The results of this study indicate that with both in-brace and out-of-brace protocols for radiographic follow-up, a similar rate of curve progression can be expected over time in IS patients with failed brace treatment

Are language production problems apparent in adults who no longer meet diagnostic criteria for attention-deficit/hyperactivity disorder?

In this study, we examined sentence production in a sample of adults (N = 21) who had had attention-deficit/hyperactivity disorder (ADHD) as children, but as adults no longer met DSM-IV diagnostic criteria (APA, 2000). This “remitted” group was assessed on a sentence production task. On each trial, participants saw two objects and a verb. Their task was to construct a sentence using the objects as arguments of the verb. Results showed more ungrammatical and disfluent utterances with one particular type of verb (i.e., participle). In a second set of analyses, we compared the remitted group to both control participants and a “persistent” group, who had ADHD as children and as adults. Results showed that remitters were more likely to produce ungrammatical utterances and to make repair disfluencies compared to controls, and they patterned more similarly to ADHD participants. Conclusions focus on language output in remitted ADHD, and the role of executive functions in language production