Intrinsic avalanches and collective phenomena in a Mn(II)-free radical ferrimagnetic chain

Magnetic hysteresis loops below 300 mK on single crystals of the Mn(II) - nitronyl nitroxide free radical chain (Mn(hfac)_2({\it R})-3MLNN) present abrupt reversals of the magnetization, or avalanches. We show that, below 200 mK, the avalanches occur at a constant field, independent of the sample and so propose that this avalanche field is an intrinsic property. We compare this field to the energy barrier existing in the sample and conclude that the avalanches are provoked by multiple nucleation of domain-walls along the chains. The different avalanche field observed in the zero field cooled magnetization curves suggests that the avalanche mechanisms are related to the competition between ferromagnetic and antiferromagnetic order in this compound.Comment: 9 pages, 7 fig, to be published in Phys. Rev.

A Novel Survey Tool to Quantify the Degree and Duration of STEMI Regionalization Across California.

IntroductionCalifornia has been a global leader in regionalization efforts for time-critical medical conditions. A total of 33 local emergency medical service agencies (LEMSAs) exist, providing an organized EMS framework across the state for almost 40 years. We sought to develop a survey tool to quantify the degree and duration of ST-elevation myocardial infarction (STEMI) regionalization over the last decade in California.MethodsThe project started with the development of an 8-question survey tool via a multi-disciplinary expert consensus process. Next, the survey tool was distributed at the annual meeting of administrators and medical directors of California LEMSAs to get responses valid through December, 2014. The first scoring approach was the Total Regionalization Score (TRS) and used answers from all 8 questions. The second approach was called the Core Score, and it focused on only 4 survey questions by assuming that the designation of STEMI Receiving Centers must have occurred at the beginning of any LEMSA's regionalization effort. Scores were ranked and grouped into tertiles.ResultsAll 33 LEMSAs in California participated in this survey. The TRS ranged from 15 to 162. The Core Score range was much narrower, from 2 to 30. In comparing TRS and Core Score rankings, the top-tertiles were quite similar. More rank variation occurred between mid- and low-tertiles.ConclusionThis study evaluated the degree and duration of STEMI network regionalization from 2004 to 2014 in California, and ranked 33 LEMSAs into tertiles based upon their TRS and their Core Score. Successful application of the 8-item survey and ranking strategies across California suggests that this approach can be used to assess regionalization in other states or countries around the world

Minimising gear conflict and resource sharing issues in the Shark Bay trawl fisheries and promotion of scallop recruitment

Objectives 1. To determine size specific recapture mortality rates of Amusium balloti as a result of repeated capture and release experiments and gear impacts on newly recruited (juvenile) scallops. 2. To determine the impacts of various scallop mesh sizes for the capture of the target size of Amusium balloti and its impact on damage to and retention of prawns. 3. To investigate if small-scale spatial closures assist recruitment of Amusium balloti by reducing gear impacts and capture mortality but without affecting overall prawn catches. 4. To examine whether existing hydrodynamic models can guide the selection of spatial closures and to investigate the larval transport mechanisms of both prawn and scallop larvae in Shark Bay

Criterios de calidad y evaluación: un instrumento de medición para el área de la lengua alemana

La Xarxa Universitària sobre Responsabilitat Social és una xarxa de més de 40 universitats d'Alemanya i Àustria establerta el 2009 que volen fer realitat i ampliar la seva responsabilitat social promovent sistemàticament la participació a la societat civil d'estudiants, professors i altres membres universitaris, vinculant-ho amb la seva missió educativa per influir activament en la societat i contribuir a la transferència mútua de coneixements. L'aprenentatge servei (ApS) és una manera de fer-ho. El 2018, un taller va iniciar una discussió entre representants del món acadèmic i de la societat civil. El focus era analitzar els criteris de qualitat de l’ApS. El grup va plantejar deu criteris diferents que proporcionen un marc de referència per a les diferents manifestacions de l’ApS a la comunitat. A partir d'aquests criteris, es van desenvolupar procediments i instruments adequats per oferir als actors orientació i suggeriments per a la implementació i avaluació dels projectes d’ApS.The University Network on Social Responsibility is a network of more than 40 universities in Germany and Austria established in 2009 that want to realise and expand their social responsibility by systematically promoting the civil society engagement of students, teachers, and other members of higher education, linking this with their educational mission and thus actively influencing society and contributing to the mutual transfer of knowledge. This can be done through the teaching-learning format of service learning (SL). In 2018, a workshop initiated a discussion between representatives of academia and civil society. The focus was the aspect of quality of SL. The group came up with ten different criteria which provide a frame of reference for the different manifestations of SL in the community. Based on these criteria, suitable procedures and instruments were developed to provide SL actors with orientation and suggestions for the implementation and evaluation of SL projects.La Red Universitaria sobre Responsabilidad Social es una red de más de 40 universidades en Alemania y Austria, establecida en 2009, que desean realizar y expandir su responsabilidad social promoviendo sistemáticamente la participación de la sociedad civil de estudiantes, docentes y otros miembros universitarios, vinculando con su misión educativa para influir activamente en la sociedad y contribuir a la transferencia mutua de conocimientos. Ello se puede hacer a través del aprendizaje-servicio (ApS). En 2018, un taller inició un debate entre representantes de la academia y la sociedad civil. El foco fue los aspectos de calidad del ApS. El grupo ideó diez criterios diferentes que proporcionan un marco de referencia para las diferentes manifestaciones de ApS en la comunidad. Con base en estos criterios, se desarrollaron procedimientos e instrumentos adecuados para proporcionar a los actores orientación y sugerencias para la implementación y evaluación de proyectos de ApS

Subtle competition between ferromagnetic and antiferromagnetic order in a Mn(II) - free radical ferrimagnetic chain

The macroscopic magnetic characterization of the Mn(II) - nitronyl nitroxide free radical chain (Mn(hfac)2(R)-3MLNN) evidenced its transition from a 1-dimensional behavior of ferrimagnetic chains to a 3-dimensional ferromagnetic long range order below 3 K. Neutron diffraction experiments, performed on a single crystal around the transition temperature, led to a different conclusion : the magnetic Bragg reflections detected below 3 K correspond to a canted antiferromagnet where the magnetic moments are mainly oriented along the chain axis. Surprisingly in the context of other compounds in this family of magnets, the interchain coupling is antiferromagnetic. This state is shown to be very fragile since a ferromagnetic interchain arrangement is recovered in a weak magnetic field. This peculiar behavior might be explained by the competition between dipolar interaction, shown to be responsible for the antiferromagnetic long range order below 3 K, and exchange interaction, the balance between these interactions being driven by the strong intrachain spin correlations. More generally, this study underlines the need, in this kind of molecular compounds, to go beyond macroscopic magnetization measurements.Comment: 12 pages, 10 figures, submitted to Phys. Rev.

Experimental testing of bionic peripheral nerve and muscle interfaces: animal model considerations

Introduction: Man-machine interfacing remains the main challenge for accurate and reliable control of bionic prostheses. Implantable electrodes in nerves and muscles may overcome some of the limitations by significantly increasing the interface's reliability and bandwidth. Before human application, experimental preclinical testing is essential to assess chronic in-vivo biocompatibility and functionality. Here, we analyze available animal models, their costs and ethical challenges in special regards to simulating a potentially life-long application in a short period of time and in non-biped animals. Methods: We performed a literature analysis following the PRISMA guidelines including all animal models used to record neural or muscular activity via implantable electrodes, evaluating animal models, group size, duration, origin of publication as well as type of interface. Furthermore, behavioral, ethical, and economic considerations of these models were analyzed. Additionally, we discuss experience and surgical approaches with rat, sheep, and primate models and an approach for international standardized testing. Results: Overall, 343 studies matched the search terms, dominantly originating from the US (55%) and Europe (34%), using mainly small animal models (rat: 40%). Electrode placement was dominantly neural (77%) compared to muscular (23%). Large animal models had a mean duration of 135 ± 87.2 days, with a mean of 5.3 ± 3.4 animals per trial. Small animal models had a mean duration of 85 ± 11.2 days, with a mean of 12.4 ± 1.7 animals. Discussion: Only 37% animal models were by definition chronic tests (>3 months) and thus potentially provide information on long-term performance. Costs for large animals were up to 45 times higher than small animals. However, costs are relatively small compared to complication costs in human long-term applications. Overall, we believe a combination of small animals for preliminary primary electrode testing and large animals to investigate long-term biocompatibility, impedance, and tissue regeneration parameters provides sufficient data to ensure long-term human applications

Detection of pathogenic Bacteria by Electrochemical Impedance Spectroscopy: Influence of the immobilization strategies on the sensor performance

Electrochemical impedance spectroscopy (EIS) is applied to detect pathogenic E. coli O157:H7 bacteria via a label free immunoassay-based detection method. Polyclonal anti-E.coli antibodies (PAb) are immobilized onto gold electrodes following two different strategies, via chemical bond formation between antibody amino groups and a carboxylic acid containing self-assembled molecular monolayer (SAM) and alternatively by linking a biotinylated anti-E. coli to Neutravidin on a mixed-SAM. Impedance spectra for sensors of both designs for increasing concentrations of E. coli are recorded in phosphate buffered saline (PBS). The Nyquist plots can be modeled with a Randle equivalent circuit, identifying the charge transfer resistance RCT as the relevant concentration dependent parameter. Sensors fabricated from both designs are able to detect very low concentration of E. coli with limits of detection as low as 10-100 cfu/ml. The influence of the different immobilization protocols on the sensor performance is evaluated in terms of sensitivity, dynamic range and resistance against nonspecific absorption

Is an Impacted Morselized Graft in a Cage an Alternative for Reconstructing Segmental Diaphyseal Defects?

Large diaphyseal bone defects often are reconstructed with large structural allografts but these are prone to major complications. We therefore asked whether impacted morselized bone graft could be an alternative for a massive structural graft in reconstructing large diaphyseal bone defects. Defects in the femora of goats were reconstructed using a cage filled with firmly impacted morselized allograft or with a structural cortical autograft (n = 6 in both groups). All reconstructions were stabilized with an intramedullary nail. The goats were allowed full weightbearing. In all reconstructions, the grafts united radiographically. Mechanical torsion strength of the femur with the cage and structural cortical graft reconstructions were 66.6% and 60.3%, respectively, as compared with the contralateral femurs after 6 months. Histologically, the impacted morselized graft was replaced completely by new viable bone. In the structural graft group, a mixture of new and necrotic bone was present. Incorporation of the impacted graft into new viable bone suggests this type of reconstruction may be safer than reconstruction with a structural graft in which creeping substitution results in a mixture of viable and necrotic bone that can fracture. The data suggest that a cage filled with a loaded morselized graft could be an alternative for the massive cortical graft in reconstruction of large diaphyseal defects in an animal model