Direct Observation of Second Order Atom Tunnelling

Tunnelling of material particles through a classically impenetrable barrier constitutes one of the hallmark effects of quantum physics. When interactions between the particles compete with their mobility through a tunnel junction, intriguing novel dynamical behaviour can arise where particles do not tunnel independently. In single-electron or Bloch transistors, for example, the tunnelling of an electron or Cooper pair can be enabled or suppressed by the presence of a second charge carrier due to Coulomb blockade. Here we report on the first direct and time-resolved observation of correlated tunnelling of two interacting atoms through a barrier in a double well potential. We show that for weak interactions between the atoms and dominating tunnel coupling, individual atoms can tunnel independently, similar to the case in a normal Josephson junction. With strong repulsive interactions present, two atoms located on one side of the barrier cannot separate, but are observed to tunnel together as a pair in a second order co-tunnelling process. By recording both the atom position and phase coherence over time, we fully characterize the tunnelling process for a single atom as well as the correlated dynamics of a pair of atoms for weak and strong interactions. In addition, we identify a conditional tunnelling regime, where a single atom can only tunnel in the presence of a second particle, acting as a single atom switch. Our work constitutes the first direct observation of second order tunnelling events with ultracold atoms, which are the dominating dynamical effect in the strongly interacting regime. Similar second-order processes form the basis of superexchange interactions between atoms on neighbouring lattice sites of a periodic potential, a central component of quantum magnetism.Comment: 18 pages, 4 figures, accepted for publication in Natur

One-dimensional phase transitions in a two-dimensional optical lattice

A phase transition for bosonic atoms in a two-dimensional anisotropic optical lattice is considered. If the tunnelling rates in two directions are different, the system can undergo a transition between a two-dimensional superfluid and a one-dimensional Mott insulating array of strongly coupled tubes. The connection to other lattice models is exploited in order to better understand the phase transition. Critical properties are obtained using quantum Monte Carlo calculations. These critical properties are related to correlation properties of the bosons and a criterion for commensurate filling is established.Comment: 14 pages, 8 figure

Computer-aided recording of automatic endoscope washing and disinfection processes as an integral part of medical documentation for quality assurance purposes

<p>Abstract</p> <p>Background</p> <p>The reprocessing of medical endoscopes is carried out using automatic cleaning and disinfection machines. The documentation and archiving of records of properly conducted reprocessing procedures is the last and increasingly important part of the reprocessing cycle for flexible endoscopes.</p> <p>Methods</p> <p>This report describes a new computer program designed to monitor and document the automatic reprocessing of flexible endoscopes and accessories in fully automatic washer-disinfectors; it does not contain nor compensate the manual cleaning step. The program implements national standards for the monitoring of hygiene in flexible endoscopes and the guidelines for the reprocessing of medical products. No FDA approval has been obtained up to now. The advantages of this newly developed computer program are firstly that it simplifies the documentation procedures of medical endoscopes and that it could be used universally with any washer-disinfector and that it is independent of the various interfaces and software products provided by the individual suppliers of washer-disinfectors.</p> <p>Results</p> <p>The computer program presented here has been tested on a total of four washer-disinfectors in more than 6000 medical examinations within 9 months.</p> <p>Conclusions</p> <p>We present for the first time an electronic documentation system for automated washer-disinfectors for medical devices e.g. flexible endoscopes which can be used on any washer-disinfectors that documents the procedures involved in the automatic cleaning process and can be easily connected to most hospital documentation systems.</p

Morphological and evolutionary insights into the keystone element of the human foot’s medial longitudinal arch

The evolution of the medial longitudinal arch (MLA) is one of the most impactful adaptations in the hominin foot that emerged with bipedalism. When and how it evolved in the human lineage is still unresolved. Complicating the issue, clinical definitions of flatfoot in living Homo sapiens have not reached a consensus. Here we digitally investigate the navicular morphology of H. sapiens (living, archaeological, and fossil), great apes, and fossil hominins and its correlation with the MLA. A distinctive navicular shape characterises living H. sapiens with adult acquired flexible flatfoot, while the congenital flexible flatfoot exhibits a ‘normal’ navicular shape. All H. sapiens groups differentiate from great apes independently from variations in the MLA, likely because of bipedalism. Most australopith, H. naledi, and H. floresiensis navicular shapes are closer to those of great apes, which is inconsistent with a human-like MLA and instead might suggest a certain degree of arboreality. Navicular shape of OH 8 and fossil H. sapiens falls within the normal living H. sapiens spectrum of variation of the MLA (including congenital flexible flatfoot and individuals with a well-developed MLA). At the same time, H. neanderthalensis seem to be characterised by a different expression of the MLA. © 2023, Springer Nature Limited

The talar morphology of a hypochondroplasic dwarf: A case study from the Italian Late Antique period

This project aims to test whether geometric morphometric (GM) and trabecular analyses may be useful tools in identifying talar characteristics related to hypochondroplasia. We quantified the external and internal talar morphology of a hypochondroplasic dwarf (T17) from Modena (northern Italy) dated to the sixth century AD. External talar morphology of T17 was compared with a broad sample of modern human tali (n = 159) using GM methods. Additionally, a subsample of these tali (n = 41) was used to investigate whole talar trabecular changes in T17. Our results show that GM and trabecular analyses identify a combination of traits linked to the dwarfing disorder of hypochondroplasia. These traits include decreased scaled talar dimensions compared with normal-sized individuals, presence of an accessory antero-lateral talar facet, high bone volume fraction, and high anisotropy values throughout the entire talus. In our case study, hypochondroplasia does not appear to substantially modify external talar morphology probably due to the fast growth of the talus. We suggest that small talar dimensions are associated with hypochondroplasia. An antero-lateral talar facet may result from the talus and calcaneus coalition (i.e., talocalcaneal abnormal bridging) possibly related to an everted foot posture that was limited by overgrowth of the fibula. We suggest that high talar trabecular density and strut orientation provide insights into pathological development of the trabecular plates in T17. Finally, our study suggests that high talar trabecular density and strut orientation, and small talar dimensions, may be added as possible concomitant talar hallmarks for hypochondroplasia

Metacarpal trabecular bone varies with distinct hand-positions used in hominid locomotion

Trabecular bone remodels during life in response to loading and thus should, at least in part, reflect potential variation in the magnitude, frequency and direction of joint loading across different hominid species. Here we analyse the trabecular structure across all non-pollical metacarpal distal heads (Mc2-5) in extant great apes, expanding on previous volume of interest and whole-epiphysis analyses that have largely focussed on only the first or third metacarpal. Specifically, we employ both a univariate statistical mapping and a multivariate approach to test for both inter-ray and interspecific differences in relative trabecular bone volume fraction (RBV/TV) and degree of anisotropy (DA) in Mc2-5 subchondral trabecular bone. Results demonstrate that while DA values only separate Pongo from African apes (Pan troglodytes, Pan paniscus, Gorilla gorilla), RBV/TV distribution varies with the predicted loading of the metacarpophalangeal (McP) joints during locomotor behaviours in each species. Gorilla exhibits a relatively dorsal distribution of RBV/TV consistent with habitual hyper-extension of the McP joints during knuckle-walking, whereas Pongo has a palmar distribution consistent with flexed McP joints used to grasp arboreal substrates. Both Pan species possess a disto-dorsal distribution of RBV/TV, compatible with multiple hand postures associated with a more varied locomotor regime. Further inter-ray comparisons reveal RBV/TV patterns consistent with varied knuckle-walking postures in Pan species in contrast to higher RBV/TV values toward the midline of the hand in Mc2 and Mc5 of Gorilla, consistent with habitual palm-back knuckle-walking. These patterns of trabecular bone distribution and structure reflect different behavioural signals that could be useful for determining the behaviours of fossil hominins

Trabecular architecture in the sciuromorph femoral head: allometry and functional adaptation

Background: Sciuromorpha (squirrels and close relatives) are diverse in terms of body size and locomotor behavior. Individual species are specialized to perform climbing, gliding or digging behavior, the latter being the result of multiple independent evolutionary acquisitions. Each lifestyle involves characteristic loading patterns acting on the bones of sciuromorphs. Trabecular bone, as part of the bone inner structure, adapts to such loading patterns. This network of thin bony struts is subject to bone modeling, and therefore reflects habitual loading throughout lifetime. The present study investigates the effect of body size and lifestyle on trabecular structure in Sciuromorpha. Methods: Based upon high-resolution computed tomography scans, the femoral head 3D inner microstructure of 69 sciuromorph species was analyzed. Species were assigned to one of the following lifestyle categories: arboreal, aerial, fossorial and semifossorial. A cubic volume of interest was selected in the center of each femoral head and analyzed by extraction of various parameters that characterize trabecular architecture (degree of anisotropy, bone volume fraction, connectivity density, trabecular thickness, trabecular separation, bone surface density and main trabecular orientation). Our analysis included evaluation of the allometric signals and lifestyle-related adaptation in the trabecular parameters. Results: We show that bone surface density, bone volume fraction, and connectivity density are subject to positive allometry, and degree of anisotropy, trabecular thickness, and trabecular separation to negative allometry. The parameters connectivity density, bone surface density, trabecular thickness, and trabecular separation show functional signals which are related to locomotor behavior. Aerial species are distinguished from fossorial ones by a higher trabecular thickness, lower connectivity density and lower bone surface density. Arboreal species are distinguished from semifossorial ones by a higher trabecular separation. Conclusion: This study on sciuromorph trabeculae supplements the few non-primate studies on lifestyle-related functional adaptation of trabecular bone. We show that the architecture of the femoral head trabeculae in Sciuromorpha correlates with body mass and locomotor habits. Our findings provide a new basis for experimental research focused on functional significance of bone inner microstructure

Microvascular decompression may be an effective treatment for nervus intermedius neuralgia

AbstractObjective:To report microvascular decompression as a possible effective treatment for patients with nervus intermedius neuralgia, and to contribute to the literature regarding both this syndrome and this specific form of treatment.Method:Case report of a patient with intermedius neuralgia. The main complaint was severe otalgia in the area innervated by the nervus intermedius, possibly caused by neurovascular compression of the nervus intermedius by the anterior inferior cerebellar artery. Microvascular decompression was undertaken, with good results.Results:Post-operatively, the patient felt immediate and total relief of her otalgia, with normal facial nerve function and no otological morbidity. One year post-operatively, she was still free from otalgia.Conclusion:Patients with nervus intermedius neuralgia who do not respond to medical treatment may benefit from microvascular decompression.</jats:sec