Transport of magnetic vortices by surface acoustic waves

In a thin film of superconducting YBCO the impact of surface acoustic waves (SAWs) traveling on the piezoelectric substrate is investigated. A pronounced interaction between the ultrasonic waves and the vortex system in the type II superconductor is observed. The occurrence of a SAW-induced dc voltage perpendicular to the sound path is interpreted as {\em dynamic pinning} of vortices by the piezoacoustic SAW, which acts as a conveyor for the fluxquanta. Its antisymmetry with respect to the magnetic field directly evidences the induced, directed flux motion.This dynamic manipulation of vortices can be seen as an important step towards flux-based electronic devices.Comment: submitte

Ultrasonic Attenuation in the Vortex State of d-wave Superconductors

We calculate the low temperature quasi-particle contribution to the ultrasonic attenuation rate in the mixed state of d-wave superconductors. Our calculation is performed within the semi-classical approximation using quasi-particle energies that are Doppler shifted, with respect to their values in the Meissner phase, by the supercurrent associated with the vortices. We find that the attenuation at low temperatures and at fields $H_{c1} \leq H \ll H_{c2}$ has a temperature independent contribution which is proportional to $\surd H$ where $H$ is the applied magnetic field. We indicate how our result in combination with the zero-field result for ultrasonic attenuation can be used to calculate one of the parameters $v_F$, $H_{c2}$ or $\xi$ given the values for any two of them.Comment: 10 pages, RevTeX, submitted to Physica

Отказоустойчивый многофазный асинхронный электропривод с несинусоидальными токами

Рассмотрен принцип построения многофазного асинхронного электропривода, позволяющего при неоднократных отказах преобразователя частоты и двигателя обеспечить отказоустойчивое управление, на основе программируемых несинусоидальных токов с восстановлением работоспособности за счет активизации алгоритма восстановления в управляющем микроконтроллере. Приведены результаты моделирования для аварийной ситуации типа "обрыв фазы" для случая трехфазного двигателя с частичным восстановлением работоспособности асинхронного двигателя

Interference of a first-order transition with the formation of a spin-Peierls state in alpha'-NaV2O5?

We present results of high-resolution thermal-expansion and specific-heat measurements on single crystalline alpha'-NaV2O5. We find clear evidence for two almost degenerate phase transitions associated with the formation of the dimerized state around 33K: A sharp first-order transition at T1=(33+-0.1)K slightly below the onset of a second-order transition at T2onset around (34+-0.1)K. The latter is accompanied by pronounced spontaneous strains. Our results are consistent with a structural transformation at T1 induced by the incipient spin-Peierls (SP) order parameter above T2=TSP.Comment: 5 pages, 7 figure

A 3’-UTR sequence element modifies chromatin and regulates alternative splicing

The 3’-untranslated regions (3’-UTRs) of protein coding transcripts play a well established role as cis regulators of RNA stability and protein translation. Recent findings also point to functions in the nucleus. This thesis reports on the analysis of a specific 3’-UTR, referred to here as CU-RNA, originating from the CDV3 gene (carnitine deficiency-associated gene expressed in ventricle 3) that was previously identified as a 3’-UTR with a putative nuclear function. In an initial characterisation of CU-RNA it was shown that it has nuclear functions due to the following criteria: (i) the transcript was able to rescue RNase A-induced chromatin aggregation, (ii) the transcript remained within the nucleus after microinjection, (iii) the endogenous transcript was present in the nucleus, (iv) by immobilizing the RNA at a specific genomic locus it was shown that locally tethered CU-RNA induces chromatin compaction, demonstrating its chromatin modifying activity. This chromatin recruitment system was subsequently used to investigate the mechanism of action of CU-RNA. It was found that CU-RNA derived fragments recruit enhancer of zeste homolog 2 (EZH2), the enzyme that sets trimethylation of histone H3 at lysine 27 (H3K27me3). By deletion analysis a CU-RNA sequence element, CU-RNA-T0, was identified that was necessary to also induce H3K27me3. The splicing regulators PTBP1 (polypyrimidine tract binding protein 1) and U2AF2 (U2 small nuclear RNA auxiliary factor 2), and the H3K27me3-promoting factor HNRNPK (heterogeneous nuclear ribonucleoprotein K) were found to specifically interact with CU-RNA-T0. In contrast, an alternative splicing variant of CDV3 that lacks the T0 element (CU-RNA-ΔT0) and did not induce H3K27me3, bound the splice factor HNRNPC (heterogeneous nuclear ribonucleoprotein C). It was therefore investigated whether the H3K27me3 inducing activity of CU-RNA-T0 affects splicing. Reducing the H3K27me3 level at the CDV3 locus by inhibition of EZH2 enzymatic activity indeed changed the ratio of the CDV3 transcript variant levels. Based on these results a model is proposed, in which the CU-RNA-T0 element regulates alternative splicing of its own transcript, the CDV3, via a feedback loop that establishes a specific chromatin signature. Thereby stable steady-state levels between the splicing variants are regulated that might be distinct with respect to their 3’-UTR sequence dependent cytoplasmic activities. This contribution to the understanding of the mechanism governing alternative splicing is of great importance to be able to develop novel drugs targeting deregulated alternative splicing in cancer

Risk of infection with SARS-CoV-2 in professional orchestras and choirs

Einleitung: Das Ende 2019/Anfang 2020 aufgekommene SARS-CoV-2 bildete eine globale Pandemie, die bisher in mehreren Wellen verlief. Neben der häufigsten Manifestation einer Erkrankung der oberen Atemwege, kann das SARS-CoV-2 insbesondere bei Patient:innen mit Vorerkrankungen zu einem Lungenversagen mit potentiell tödlichem Ausgang führen. Der Übertragungsweg erfolgt hauptsächlich aerogen durch Einatmen virushaltiger Aerosole. Wir erforschen in dieser epidemiologischen Studie, ob in professionellen Orchestern und Chören durch die Exposition während Proben und Konzerten eine höhere Ansteckungsgefahr als in einer Kontrollgruppe besteht. Zusätzlich wurde wird die Häufigkeit von anderweitigen Atemwegserkrankungen sowie die Anzahl der Krankheitstage erhoben. Methodik: Studienteilnehmer:innen von 23 Kulturinstitutionen in ganz Deutschland wurden je nach beruflicher Aktivität in eine Orchester- eine Chor- oder eine Kontrollgruppe eingeteilt. Zusätzlich zum Baseline-Fragebogen erfolgte eine wöchentliche Befragung durch Follow-Up- Fragebögen über insgesamt 38 Wochen. In den Fragebögen wurden die berufliche Aktivität, individuelle Risikofaktoren für eine Infektion sowie positive Testung auf das SARS-CoV-2 abgefragt. Zwischen den Gruppen wurde anhand eines „mixed-effects cox proportional hazards“-Modells das Risiko für eine Infektion mit dem SARS-CoV-2 verglichen. Die Adjustierung auf das individuelle Risikoverhalten erfolgte anhand eines aus den Fragebogenparametern gebildeten Risiko-Scores. Ergebnisse: Es wurden 1097 Studienteilnehmer:innen mit einem Durchschnittsalter von 46,7 (SD 10,3) Jahren befragt, davon 705 Orchestermusiker:innen, 154 Chorsänger:innen und 238 Kontrollen. 46,8% der Studienteilnehmenden sind weiblich, 0,2% divers. Insgesamt traten 40 Fälle einer Infektion mit dem SARS-CoV-2 auf, 26 in der Orchestergruppe, zehn in der Chorgruppe, vier in der Kontrollgruppe. Das Hazard Ratio im Vergleich zur Kontrollgruppe betrug 1,74 (95% CI: 0,58-5,25) für die Orchestergruppe und 2,97 (95% CI: 0,87-10,28) für die Chorgruppe. Die Mehrzahl der infizierten Studienteilnehmer:innen vermuteten eine Ansteckung in ihrem privaten Umfeld. Die Krankheit verlief in allen registrierten Fällen mild bis moderat. Andere Atemwegserkrankungen traten in 6,1% aller Studienwochen in der Orchestergruppe, 10,1% aller Studienwochen in der Chorgruppe, 8,0% aller Studienwochen in der Kontrollgruppe auf. Die Zahl der Erkrankungstage im Laufe der Befragung betrug respektive 0,5%; 2,1% und 1,3%. Diskussion: Diese epidemiologische Studie zur Übertragungswahrscheinlichkeit von SARS- CoV-2 zeigte keine Hinweise auf ein signifikant erhöhtes Risiko einer Infektion mit dem SARS- CoV-2 bei Orchestergruppen und ein tendenziell höheres Risiko einer SARS-CoV-2 Infektionbei der Chorgruppe im Vergleich zur Kontrollgruppe. Die genauen Infektionswege wurden durch die Studie nicht erfasst.Introduction: SARS-CoV-2, which emerged in late 2019/early 2020, formed a global pandemic that occurred in several waves. In addition to the most common manifestation of upper respiratory illness, SARS-CoV-2 can lead to lung failure with a potential fatal outcome, especially in patients with previous illnesses. The routes of transmission are mainly aerogenic through inhalation of virus-containing aerosols. In this epidemiological study, we are investigating whether exposure during rehearsals and concerts in professional orchestras and choirs increases the risk of infection compared to a control group. The frequency of other respiratory diseases and the number of days of illness will also be recorded. Methodology: The study participants from 23 cultural institutions throughout Germany were divided into an orchestra, a choir or a control group according to their professional activity. In addition to the baseline questionnaire, weekly follow-up questionnaires were sent to study participants for a total of 38 weeks. The questionnaires enquired about occupational activity, individual risk factors relating to infection and positive testing for SARS-CoV-2. A mixed-effects cox proportional hazards model was used to compare the risk of infection with SARS-CoV-2 between the study groups. We formed a risk score using questionary items to adjust for individual risk behavior. Results: 1097 study participants with a mean age of 46.7 (SD 10.3) years were interviewed, including 705 orchestral musicians, 154 choral singers and 238 controls. 46.8% of the study participants were female, 0.2% were diverse. A total of 40 cases of SARS-CoV-2 infection occurred, 26 in the orchestra group, ten in the choir group, four in the control group. The hazard ratio compared to the control group was 1.74 (95% CI 0.58-5.25) for the orchestra group and 2.97 (0.87-10.28) for the choir group. The majority of infected study participants suspected infection in their private environment. The course of disease was mild to moderate in all cases. Other respiratory diseases occurred in 6.1% of all study weeks in the orchestra group, 10.1% of all study weeks in the choir group, 8.0% of all study weeks in the control group. The number of days of illness during the survey was respectively 0.5%; 2.1% and 1.3%. Discussion: This epidemiological study on the transmission probability of SARS-CoV-2 shows no evidence of a significantly increased risk of infection with SARS-CoV-2 in orchestra groups and a tendency towards a higher risk of SARS-CoV-2 infection in the choir group compared to the control group. The exact routes of infection were not recorded by the study

Minimal renormalization without epsilon-expansion: Amplitude functions in three dimensions below T_c

Massive field theory at fixed dimension d<4 is combined with the minimal subtraction scheme to calculate the amplitude functions of thermodynamic quantities for the O(n) symmetric phi^4 model below T_c in two-loop order. Goldstone singularities arising at an intermediate stage in the calculation of O(n) symmetric quantities are shown to cancel among themselves leaving a finite result in the limit of zero external field. From the free energy we calculate the amplitude functions in zero field for the order parameter, specific heat and helicity modulus (superfluid density) in three dimensions. We also calculate the q^2 part of the inverse of the wavenumber-dependent transverse susceptibility chi_T(q) which provides an independent check of our result for the helicity modulus. The two-loop contributions to the superfluid density and specific heat below T_c turn out to be comparable in magnitude to the one-loop contributions, indicating the necessity of higher-order calculations and Pade-Borel type resummations.Comment: 41 pages, LaTeX, 8 PostScript figures, submitted to NPB [FS

SARS-CoV-2 infections in professional orchestra and choir musicians—a prospective cohort study

During the COVID-19 pandemic, rehearsal and concert activities of professional orchestras and choirs were severely restricted based on the assumption of particularly high infection risks associated with wind instruments and singing. Therefore, our primary objective was to determine the incidence of SARS-CoV-2 infections in orchestra and choir musicians compared to controls. We also assessed influenza, flu, upper respiratory tract infections, and course of illness. Musicians from professional orchestras and choirs and controls from 23 institutions throughout Germany were included in a prospective cohort study. Data were collected from October 2020 to June 2021 by weekly online surveys. A mixed-effects cox proportional hazards model was used to assess the effect of exposure by professional activity on SARS-CoV-2 infection. In 1,097 participants (46.7 years (SD 10.3); 46.8% female; 705 orchestra, 154 choir, and 238 control subjects) 40 SARS-CoV-2 infections occurred. Cases per person-years were 0.06 in orchestras, 0.11 in choirs, and 0.03 in controls. Hazard ratios compared to controls were 1.74 (95% CI 0.58 to 5.25, p = 0.320) for orchestra musicians and 2.97 (0.87 to 10.28, p = 0.087) for choir singers. Infection source was suspected predominantly in private contexts. Disease courses were mild to moderate. Other respiratory infections were reported in 6.1% of study weeks in orchestras, 10.1% in choirs, and 8.0% in controls. Sick leave days of total study days were 0.5, 2.1 and 1.3%, respectively. This epidemiologic study during the pandemic in professional musicians indicates no increased risk of SARS-CoV-2 infections in orchestra musicians and a trend towards increased risk in choir singers compared to controls. However, the exact routes of infection could not be validated. If appropriate hygiene concepts are adhered to, safe orchestra and choir activity appears possible in pandemic times

Design and Motion Planning for a Reconfigurable Robotic Base

A robotic platform for mobile manipulation needs to satisfy two contradicting requirements for many real-world applications: A compact base is required to navigate through cluttered indoor environments, while the support needs to be large enough to prevent tumbling or tip over, especially during fast manipulation operations with heavy payloads or forceful interaction with the environment. This paper proposes a novel robot design that fulfills both requirements through a versatile footprint. It can reconfigure its footprint to a narrow configuration when navigating through tight spaces and to a wide stance when manipulating heavy objects. Furthermore, its triangular configuration allows for high-precision tasks on uneven ground by preventing support switches. A model predictive control strategy is presented that unifies planning and control for simultaneous navigation, reconfiguration, and manipulation. It converts task-space goals into whole-body motion plans for the new robot. The proposed design has been tested extensively with a hardware prototype. The footprint reconfiguration allows to almost completely remove manipulation-induced vibrations. The control strategy proves effective in both lab experiment and during a real-world construction task.Comment: 8 pages, accepted for RA-L and IROS 202

Biocompatibility and functionality of a tissue-engineered living corneal stroma transplanted in the feline eye

PURPOSE. Corneal tissue shortage has become a major concern worldwide, which has motivated the search for alternative solutions to eye bank human eyes for corneal transplantation. Minimally invasive lamellar transplantation and tissue engineering may offer new opportunities for the rehabilitation of diseased corneas. The aim of this study was to evaluate the biocompatibility and functionality of stromal lamellar grafts tissue-engineered (TE) in vitro and transplanted in vivo in the cornea of a feline model. METHODS. The corneal stromas were engineered in culture from corneal stromal cells using the self-assembly approach, without the addition of exogenous material or scaffold. Eight healthy animals underwent two intrastromal grafts in one eye and the contralateral eye was used as a control. Animals were followed with slit-lamp ophthalmic examination, corneal esthesiometry and optical coherent tomography. Confocal microscopy, immunofluorescence, histology, and transmission electron microscopy (TEM) were performed at 4 months. RESULTS. Four months after transplantation, the TE-stromal grafts were transparent, functional, and well tolerated by the eye. All grafts remained avascular, with no signs of immune rejection, despite a short course of low-dose topical steroids. Corneal sensitivity returned to preoperative level and reinnervation of the grafts was confirmed by confocal microscopy and immunofluorescence. Histology and TEM of the TE-grafts showed a lamellar stromal structure with regular collagen fibril arrangement. CONCLUSIONS. These results open the way to an entirely new therapeutic modality. Intracorneal filling using a biocompatible, transparent, and malleable TE-stroma could be the basis for multiple types of novel therapeutic options in corneal interventional surgery