Theory of double-resonant Raman spectra in graphene: intensity and line shape of defect-induced and two-phonon bands

We calculate the double resonant (DR) Raman spectrum of graphene, and determine the lines associated to both phonon-defect processes, and two-phonons ones. Phonon and electronic dispersions reproduce calculations based on density functional theory corrected with GW. Electron-light, -phonon, and -defect scattering matrix elements and the electronic linewidth are explicitly calculated. Defect-induced processes are simulated by considering different kind of idealized defects. For an excitation energy of $\epsilon_L=2.4$ eV, the agreement with measurements is very good and calculations reproduce: the relative intensities among phonon-defect or among two-phonon lines; the measured small widths of the D, $D'$, 2D and $2D'$ lines; the line shapes; the presence of small intensity lines in the 1800, 2000 cm$^{-1}$ range. We determine how the spectra depend on the excitation energy, on the light polarization, on the electronic linewidth, on the kind of defects and on their concentration. According to the present findings, the intensity ratio between the $2D'$ and 2D lines can be used to determine experimentally the electronic linewidth. The intensity ratio between the $D$ and $D'$ lines depends on the kind of model defect, suggesting that this ratio could possibly be used to identify the kind of defects present in actual samples. Charged impurities outside the graphene plane provide an almost undetectable contribution to the Raman signal

Behaviour of adipose-derived canine mesenchymal stem cells after superparamagnetic iron oxide nanoparticles labelling for magnetic resonance imaging

Background: Therapy with mesenchymal stem cells (MSCs) has been reported to provide beneficial effects in the treatment of neurological and orthopaedic disorders in dogs. The exact mechanism of action is poorly understood. Magnetic resonance imaging (MRI) gives the opportunity to observe MSCs after clinical administration. To visualise MSCs with the help of MRI, labelling with an MRI contrast agent is necessary. However, it must be clarified whether there is any negative influence on cell function and viability after labelling prior to clinical administration. Results: For the purpose of the study, seven samples with canine adipose-derived stem cells were incubated with superparamagnetic iron oxide nanoparticles (SPIO: 319.2 µg/mL Fe) for 24 h. The internalisation of the iron particles occurred via endocytosis. SPIO particles were localized as free clusters in the cytoplasm or within lysosomes depending on the time of investigation. The efficiency of the labelling was investigated using Prussian blue staining and MACS assay. After 3 weeks the percentage of SPIO labelled canine stem cells decreased. Phalloidin staining showed no negative effect on the cytoskeleton. Labelled cells underwent osteogenic and adipogenic differentiation. Chondrogenic differentiation occurred to a lesser extent compared with a control sample. MTT-Test and wound healing assay showed no influence of labelling on the proliferation. The duration of SPIO labelling was assessed using a 1 Tesla clinical MRI scanner and T2 weighted turbo spin echo and T2 weighted gradient echo MRI sequences 1, 2 and 3 weeks after labelling. The hypointensity caused by SPIO lasted for 3 weeks in both sequences. Conclusions: An Endorem labelling concentration of 319.2 µg/mL Fe (448 µg/mL SPIO) had no adverse effects on the viability of canine ASCs. Therefore, this contrast agent could be used as a model for iron oxide labelling agents. However, the tracking ability in vivo has to be evaluated in further studies

The Impact of Competition on the Interconnection Industry

One of the most critical problems facing the telecommunications industry is the extent to which competition will be introduced into what has been, for the most part, a regulated industry. In the forefront of the competitive environment has been the telephone interconnection industry. The genesis of this industry was the Carterfone decision by the Federal Communications Commission which allowed competition in the interconnection field. It is the thesis of this project that the most significant factor affecting the telephone interconnection industry today is the continued impact of competition on the industry. To insure that the project stayed within manageable limits the authors chose to examine the issues dealing with that part of the interconnect industry providing for the connection of answering devices, acoustic couplers, personal custom telephones, intercom systems, key business systems, or private branch exchanges (PBX) to the telephone system. Issues surrounding the competitive interconnect services of microwave and satellite links provided by the specialized common carriers are beyond the scope of this project. The specialized common carrier area is a critical issue on its own right and should be the subject of investigation by future participants in the Telecommunications Program. An analysis of present, past and potential interconnect manufacturers is provided to show how the lure and promise of competition has affected the industry. Because there are hundreds of companies involved in the manufacture and marketing of interconnect devices, only a limited cross section has been chosen for this project

Valid model-free spatial prediction

Predicting the response at an unobserved location is a fundamental problem in spatial statistics. Given the difficulty in modeling spatial dependence, especially in non-stationary cases, model-based prediction intervals are at risk of misspecification bias that can negatively affect their validity. Here we present a new approach for model-free spatial prediction based on the {\em conformal prediction} machinery. Our key observation is that spatial data can be treated as exactly or approximately exchangeable in a wide range of settings. For example, when the spatial locations are deterministic, we prove that the response values are, in a certain sense, locally approximately exchangeable for a broad class of spatial processes, and we develop a local spatial conformal prediction algorithm that yields valid prediction intervals without model assumptions. Numerical examples with both real and simulated data confirm that the proposed conformal prediction intervals are valid and generally more efficient than existing model-based procedures across a range of non-stationary and non-Gaussian settings.Comment: 30 pages, 9 figures, 3 tables. Comments welcome at https://www.researchers.one/article/2020-06-1

Development and validation of an oligonucleotide microarray to characterise ectomycorrhizal fungal communities

Background: In forest ecosystems, communities of ectomycorrhizal fungi (ECM) are influenced by several biotic and abiotic factors. To understand their underlying dynamics, ECM communities have been surveyed with ribosomal DNA-based sequencing methods. However, most identification methods are both time-consuming and limited by the number of samples that can be treated in a realistic time frame. As a result of ongoing implementation, the array technique has gained throughput capacity in terms of the number of samples and the capacity for parallel identification of several species. Thus far, although phylochips (microarrays that are used to detect species) have been mostly developed to trace bacterial communities or groups of specific fungi, no phylochip has been developed to carry oligonucleotides for several ectomycorrhizal species that belong to different genera. Results: We have constructed a custom ribosomal DNA phylochip to identify ECM fungi. Specific oligonucleotide probes were targeted to the nuclear internal transcribed spacer (ITS) regions from 95 fungal species belonging to 21 ECM fungal genera. The phylochip was first validated using PCR amplicons of reference species. Ninety-nine percent of the tested oligonucleotides generated positive hybridisation signals with their corresponding amplicons. Cross-hybridisation was mainly restricted at the genus level, particularly for Cortinarius and Lactarius species. The phylochip was subsequently tested with environmental samples that were composed of ECM fungal DNA from spruce and beech plantation fungal communities. The results were in concordance with the ITS sequencing of morphotypes and the ITS clone library sequencing results that were obtained using the same PCR products. Conclusion: For the first time, we developed a custom phylochip that is specific for several ectomycorrhizal fungi. To overcome cross-hybridisation problems, specific filter and evaluation strategies that used spot signal intensity were applied. Evaluation of the phylochip by hybridising environmental samples confirmed the possible application of this technology for detecting and monitoring ectomycorrhizal fungi at specific sites in a routine and reproducible manner

Untersuchung der vestibulospinalen Funktionen bei Parkinsonpatienten

In der Parkinsonerkrankung stehen mit zunehmender Krankheitsdauer Gangstörungen und Stürze im Vordergrund,welche einen erheblichen Anteil an Einschränkungen der Patienten im alltäglichen Leben ergeben. An der physiologischen Kontrolle des Gehens und Stehens sind zahlreiche Hirnstammkerne beteiligt. In dieser Studie wurde untersucht, inwieweit eine Dysfunktion vestibulärer Hirnstammkerne ursächlich für die Gang- und Haltungsstörung ist,und ob diese Dysfunktion therapeutisch beeinflussbar ist. Methodisch wählten wir hierfür die etablierten neurophysiologischen Paradigmen des cVEMPs und die Soleus H-Reflexmodulation durch vertikale Körperkippung. Die Amplitude des cVEMPs zeigt deutlich reduzierte Ausprägung bei Parkinsonpatienten im Vergleich zu den Probanden. Die dopaminerge Medikation vergrößerte die Amplitude, aber normalisierte sie nicht. Die Neurostimulation hatte keinen Effekt. Die Soleus H-Reflexmodulation zeigte sich im vorbeschrieben Maße bei Normalprobanden wie auch bei unbehandelten Parkinsonpatienten. Levodopa Medikation und Neurostimulation erbrachten keine Veränderung. Diese verringerte Erregbarkeit des medialen Vestibulospinalentraktes in der Parkinsonerkrankung, die nur durch Levodopa moduliert wird bildet eine wichtige neurophysiologische Grundlage für die Balance und damit der im langen Krankheitsverlauf immer wichtiger werdenden posturalen Kontrolle. Die unterschiedliche Auslenkbarkeit der Therapieoptionen auf den vestibulospinalen Hirnstammschaltkreis weißen auf eine direkte dopaminerge Beeinflussung hin, möglicherweise auf Hirnstammniveau durch das mesolimbokortikales Systems und die Formatio reticularis. Eine Modulation der inhibitorischen Basalganglieneingangs ist wenig wahrscheinlich,diese müsste gleichsinnig unter Neurostimulation und Medikation vorliegen. Diese Ergebnisse stehen gut im Einklang mit den Beobachtungen aus klinischen Langzeitstudien,welche nur der medikamentöser Therapie eine Verbesserung auf die posturale Kontrolle zuschreiben

Dr. med. Cäsar Hirsch - ein jüdisches Arztschicksal in Stuttgart

Allein die Tatsache, dass Dr. Cäsar Hirsch von 1923 – 1933 der erste Chefarzt der Hals-Nasen-Ohrenklinik am Marienhospital in Stuttgart war, diese Klinik aufbaute und zu einem weit über Stuttgart hinausgehenden, sehr guten Ruf verhalf, wäre Grund genug, sich mit seiner Vita zu beschäftigen. Als einer seiner Nachfolger im Amt (1976 – 2003) musste ich mich bereits 2 x mit Cäsar Hirsch befassen. Das erste Mal für die Festschrift zum 100-jährigen Jubiläum des Marienhospitals 1990. Hierin habe ich die Geschichte der HNO-Klinik und ihrer Chefärzte beschrieben. Damals konnte ich nur wenige eigene Recherchen zu C.H. anstellen. Als 2001 von Tilman Brusis für die Deutsche Hals-Nasen-Ohren-Gesellschaft die Geschichte der Hals-Nasen-Ohren-Kliniken herausgegeben wurde, war ich das zweite Mal mit Cäsar Hirsch konfrontiert. 1996 stattete der Sohn von Cäsar Hirsch, Peter Hearst, Deutschland und unter anderem dem Marienhospital Stuttgart einen Besuch ab, um nach eventuell noch vorhandenen Gegenständen (Bücher, Instrumente) seines Vaters zu forschen. Leider kam es damals zu keiner Begegnung mit dem Sohn. Außerdem waren auch keine persönlichen Gegenstände von C.H. mehr vorhanden wegen der teilweisen Zerstörung des Marienhospitals im Krieg und der vielen Um- und Neubauten in der Folgezeit bis heute. Im Jahre 1999 entdeckte der Tübinger Historiker und Journalist Dr. Hans-Joachim Lang die bis dahin verschollen geglaubte Bibliothek von C.H. in der Universitätsbibliothek von Tübingen und erreichte eine Rückgabe an den Sohn, welcher die Bücher der Universitätsbibliothek von Los Angeles stiftete. Durch all diese Berührungspunkte veranlasst, war dann irgendwann die Idee vorhanden, eine Biografie und Würdigung von Dr. Cäsar Hirsch zu verfassen. Hierbei konnte ich außerdem auf Berichte und Erzählungen inzwischen verstorbener Ordensfrauen zurückgreifen, welche noch mit Cäsar Hirsch zusammengearbeitet haben. Sie waren Zeitzeugen der Flucht und der darauf folgenden dramatischen Ereignisse. Aus dem bisher Bekannten ergab sich für C.H. einerseits ein durchaus übliches "jüdisches Schicksal" unter den Nazis, andererseits hatte der Fall auch ganz persönliche Momente, welche mich veranlassten, eigene intensive Recherchen anzustellen