27 research outputs found
Impurity induced double transitions for accidentally degenerate unconventional pairing states
Non-magnetic impurities can lift the accidental degeneracy of unconventional
pairing states, such as the -wave state recently proposed for
SrRuO. This type of effect would lead to a superconducting double
transition upon impurity doping. In a model calculation it is shown how this
behavior depends on material parameters and how it could be detected.Comment: 5 pages, 3 figure
Correction of Static Posterior Shoulder Subluxation by Restoring Normal Scapular Anatomy Using Acromion and Glenoid Osteotomies: A Case Report
CASE
A 40-year-old man presented with progressive shoulder pain, associated with static posterior subluxation and mild eccentric glenohumeral osteoarthritis. Compared with a mean statistical shape model of a normal shoulder, the patient's acromion was abnormally high and horizontal, and the glenoid abnormally inclined inferiorly and minimally retroverted. Restoration of normal scapular anatomy using 3-dimensional planned acromial and glenoid osteotomies led to recentering of the joint and full shoulder function up to 24 months postoperatively.
CONCLUSION
The correction of associated acromial and glenoid malformation can revert early static posterior subluxation of the shoulder. Whether successful recentering prevents progression of osteoarthritis remains to be established
Impurity induced magnetic ordering in SrRuO
Ti substituting Ru in SrRuO in small concentrations induces
incommensurate spin density wave order with a wave vector corresponding to the nesting vector of two out of
three Fermi surface sheets. We consider a microscopic model for these two bands
and analyze the correlation effects leading to magnetic order through
non-magnetic Ti-doping. For this purpose we use a position dependent mean field
approximation for the microscopic model and a phenomenological Ginzburg-Landau
approach, which both deliver consistent results and allow us to examine the
inhomogeneous magnetic order. Spin-orbit coupling additionally leads to spin
currents around each impurity, which in combination with the magnetic
polarization produce a charge current pattern. This is also discussed within a
gauge field theory in both charge and spin channel. This spin-orbit coupling
effect causes an interesting modification of the magnetic structure, if
currents run through the system. Our findings allow a more detailed analysis of
the experimental data for SrRuTiO. In particular, we
find that the available measurements are consistent with our theoretical
predictions.Comment: 17 pages, 12 figure
Posterior stability of the shoulder depends on acromial anatomy: a biomechanical study of 3D surface models
PURPOSE
Primary glenohumeral osteoarthritis is commonly associated with static posterior subluxation of the humeral head. Scapulae with static/dynamic posterior instability feature a superiorly and horizontally oriented acromion. We investigated whether the acromion acts as a restraint to posterior humeral translation.
METHODS
Five three-dimensional (3D) printed scapula models were biomechanically tested. A statistical shape mean model (SSMM) of the normal scapula of 40 asymptomatic shoulders was fabricated. Next, a SSMM of scapular anatomy associated with posterior subluxation was generated using data of 20 scapulae ("B1"). This model was then used to generate three models of surgical correction: glenoid version, acromial orientation, and acromial and glenoid orientation. With the joint axially loaded (100N) and the humerus stabilized, an anterior translation force was applied to the scapula in 35°, 60° and 75° of glenohumeral flexion. Translation (mm) was measured.
RESULTS
In the normal scapula, the humerus translates significantly less to contact with the acromion compared to all other configurations (p < .000 for all comparisons; i.e. 35°: "normal" 8,1 mm (± 0,0) versus "B1" 11,9 mm (± 0,0) versus "B1 Acromion Correction" 12,2 mm (± 0,2) versus "B1 Glenoid Correction" 13,3 mm (± 0,1)). Restoration of normal translation was only achieved with correction of glenoid and acromial anatomy (i.e. 75°: "normal" 11 mm (± 0,8) versus "B1 Acromion Correction" 17,5 mm (± 0,1) versus "B1 Glenoid Correction" 19,7 mm (± 1,3) versus "B1 Glenoid + Acromion Correction" 11,5 mm (± 1,1)).
CONCLUSIONS
Persistence or recurrence of static/dynamic posterior instability after correction of glenoid version alone may be related to incomplete restoration of the intrinsic stability that is conferred by a normal acromial anatomy.
LEVEL OF EVIDENCE V
biomechanical study
Unsplit superconducting and time reversal symmetry breaking transitions in SrRuO under hydrostatic pressure and disorder
There is considerable evidence that the superconducting state of
SrRuO breaks time reversal symmetry. In the experiments showing time
reversal symmetry breaking its onset temperature, , is generally
found to match the critical temperature, , within resolution. In
combination with evidence for even parity, this result has led to consideration
of a order parameter. The degeneracy of the two components
of this order parameter is protected by symmetry, yielding , but it has a hard-to-explain horizontal line node at .
Therefore, and order parameters are also under
consideration. These avoid the horizontal line node, but require tuning to
obtain . To obtain evidence distinguishing
these two possible scenarios (of symmetry-protected versus accidental
degeneracy), we employ zero-field muon spin rotation/relaxation to study pure
SrRuO under hydrostatic pressure, and SrLaRuO at
zero pressure. Both hydrostatic pressure and La substitution alter
without lifting the tetragonal lattice symmetry, so if the degeneracy is
symmetry-protected should track changes in , while
if it is accidental, these transition temperatures should generally separate.
We observe to track , supporting the hypothesis of
order.Comment: 14 pages, 8 Figure
Chronic Social Stress Leads to Reduced Gustatory Reward Salience and Effort Valuation in Mice
Pathology of reward processing is a major clinical feature of stress-related neuropsychiatric disorders including depression. Several dimensions of reward processing can be impacted, including reward valuation/salience, learning, expectancy and effort valuation. To establish the causal relationships between stress, brain changes, and reward processing pathologies, valid animal models are essential. Here, we present mouse experiments investigating behavioral effects of chronic social stress (CSS) in association learning tests of gustatory reward salience and effort valuation. The reward salience test (RST) comprised Pavlovian pairing of a tone with gustatory reward. The effort valuation test (EVT) comprised operant responding for gustatory reinforcement on a progressive ratio schedule (PRS). All testing was conducted with mice at 100% baseline body weight (BBW). In one experiment, mice underwent 15-day CSS or control handling (CON) and testing was conducted using sucrose pellets. In the RST on days 16–17, CSS mice made fewer feeder responses and had a longer tone response latency, than CON mice. In a shallow EVT on days 19–20, CSS mice attained a lower final ratio than CON mice. In a second CSS experiment, mice underwent CSS or CON and testing was conducted with chocolate pellets and in the presence of standard diet (low effort/low reward). In the RST on days 16–18, CSS mice made fewer feeder responses and had a longer tone response latency, than CON mice. In a steep EVT on days 19–20, CSS and CON mice attained less pellets than in the RST, and CSS mice attained a lower final ratio than CON mice. At day 21, blood levels of glucose and the satiety adipokine leptin were similar in CSS and CON mice. Therefore, CSS leads to consistent reductions in reward salience and effort valuation in tests based on association learning. These reward pathology models are being applied to identify the underlying neurobiology and putative molecular targets for therapeutic pharmacology
An automated optimization pipeline for clinical-grade computer-assisted planning of high tibial osteotomies under consideration of weight-bearing
3D preoperative planning for high tibial osteotomies (HTO) has increasingly replaced 2D planning but is complex, time-consuming and therefore expensive. Several interdependent clinical objectives and constraints have to be considered, which often requires multiple rounds of revisions between surgeons and biomedical engineers. We therefore developed an automated preoperative planning pipeline, which takes imaging data as an input to generate a ready-to-use, patient-specific planning solution. Deep-learning based segmentation and landmark localization was used to enable the fully automated 3D lower limb deformity assessment. A 2D-3D registration algorithm allowed the transformation of the 3D bone models into the weight-bearing state. Finally, an optimization framework was implemented to generate ready-to use preoperative plannings in a fully automated fashion, using a genetic algorithm to solve the multi-objective optimization (MOO) problem based on several clinical requirements and constraints. The entire pipeline was evaluated on a large clinical dataset of 53 patient cases who previously underwent a medial opening-wedge HTO. The pipeline was used to automatically generate preoperative solutions for these patients. Five experts blindly compared the automatically generated solutions to the previously generated manual plannings. The overall mean rating for the algorithm-generated solutions was better than for the manual solutions. In 90% of all comparisons, they were considered to be equally good or better than the manual solution. The combined use of deep learning approaches, registration methods and MOO can reliably produce ready-to-use preoperative solutions that significantly reduce human workload and related health costs
Stress deficits in reward behaviour are associated with and replicated by dysregulated amygdala-nucleus accumbens pathway function in mice
Reduced reward interest/learning and reward-to-effort valuation are distinct, common symptoms in neuropsychiatric disorders for which chronic stress is a major aetiological factor. Glutamate neurons in basal amygdala (BA) project to various regions including nucleus accumbens (NAc). The BA-NAc neural pathway is activated by reward and aversion, with many neurons being monovalent. In adult male mice, chronic social stress (CSS) leads to reduced discriminative reward learning (DRL) associated with decreased BA-NAc activity, and to reduced reward-to-effort valuation (REV) associated, in contrast, with increased BA-NAc activity. Chronic tetanus toxin BA-NAc inhibition replicates the CSS-DRL effect and causes a mild REV reduction, whilst chronic DREADDs BA-NAc activation replicates the CSS effect on REV without affecting DRL. This study provides evidence that stress disruption of reward processing involves the BA-NAc neural pathway; the bi-directional effects implicate opposite activity changes in reward (learning) neurons and aversion (effort) neurons in the BA-NAc pathway following chronic stress
The SIB Swiss Institute of Bioinformatics' resources: focus on curated databases
The SIB Swiss Institute of Bioinformatics (www.isb-sib.ch) provides world-class bioinformatics databases, software tools, services and training to the international life science community in academia and industry. These solutions allow life scientists to turn the exponentially growing amount of data into knowledge. Here, we provide an overview of SIB's resources and competence areas, with a strong focus on curated databases and SIB's most popular and widely used resources. In particular, SIB's Bioinformatics resource portal ExPASy features over 150 resources, including UniProtKB/Swiss-Prot, ENZYME, PROSITE, neXtProt, STRING, UniCarbKB, SugarBindDB, SwissRegulon, EPD, arrayMap, Bgee, SWISS-MODEL Repository, OMA, OrthoDB and other databases, which are briefly described in this article
Symmetry conditions for the superconducting diode effect in chiral superconductors
We analyze the presence of nonreciprocal critical currents, the so-called superconducting diode effect, in chiral superconductors within a generalized Ginzburg-Landau framework. After deriving its key symmetry conditions we illustrate the basic mechanism for two examples, the critical current in a thin film and a Josephson junction. The appearance of spontaneous edge currents and the energy bias for the formation of Josephson vortices play an essential part in establishing a splitting of the critical currents running in opposite directions. Eventually this allows us to interpret a superconducting diode effect observed in the 3-Kelvin phase of Sr2RuO4 as evidence for spontaneously broken time-reversal symmetry in the superconducting phase.ISSN:2643-156