120 research outputs found
The c-projective symmetry algebras of K\"ahler surfaces
Let be a K\"ahler manifold with complex structure and K\"ahler metric
. A c-projective vector field is a vector field on whose flow sends
-planar curves to -planar curves, where -planar curves are analogs of
what (unparametrised) geodesics are for pseudo-Riemannian manifolds without
complex structure. The c-projective symmetry algebras of K\"ahler surfaces with
essential (i.e., non-affine) c-projective vector fields are computed
Metrics admitting projective and c-projective vector fields
Vector fields on a smooth manifold with an affine connection are called projective (resp. c-projective) if their local flows preserve geodesics (resp. J-planar curves). In this expository paper, metrics with such vector fields are discussed. Emphasis is put on Lie’s classical 1882 problem of finding a local description of surfaces with projective vector fields, known results on this problem, as well as on various extensions in the literature
Dosage calculation for intravenous thrombolysis of ischemic stroke: to weigh or to estimate?
Background: Estimation is a widely used method of assessing the weight of patients with
acute stroke. Because the dosage of tissue plasminogen activator (tPA) is weight-dependent,
errors in estimation lead to incorrect dosing. Methods: We installed a ground-level scale in
the computed tomography (CT) suite of our hospital and also integrated a scale into the CT
table of our Mobile Stroke Unit in order to prospectively assess the differences between reported,
estimated, and measured weights of acute stroke patients. An independent rater
asked patients to report their weight. The patients’ weights were also estimated by the treating
physician and measured with a scale. Differences between reported, estimated, and measured
weights were analyzed statistically. Results: For 100 consecutive patients, weighing was
possible without treatment delays. Weights estimated by the physician diverged from measured
weights by 10% or more for 27 patients and by 20% or more for 6 patients. Weights
reported by the patient diverged from measured weights by 10% or more for 12 patients.
Weights reported by the patients differed significantly less from measured weights (mean,
4.1 ± 3.1 kg) than did weights estimated by the physician (5.7 ± 4.4 kg; p = 0.003). Conclusion: This first prospective study of weight assessment in acute stroke shows that the use of an easily
accessible scale makes it feasible to weigh patients with acute stroke without the treatment
delay associated with additional patient transfers. Physicians’ estimates of patients’ weights
demonstrated substantial aberrations from measured weights. Avoiding these deviations
would improve the accuracy of tPA dosag
Driven electronic bridge processes via defect states in Th-doped crystals
The electronic defect states resulting from doping Th in CaF
offer a unique opportunity to excite the nuclear isomeric state Th at
approximately 8 eV via electronic bridge mechanisms. We consider bridge schemes
involving stimulated emission and absorption using an optical laser. The role
of different multipole contributions, both for the emitted or absorbed photon
and nuclear transition, to the total bridge rates are investigated
theoretically. We show that the electric dipole component is dominant for the
electronic bridge photon. In contradistinction, the electric quadrupole channel
of the Th isomeric transition plays the dominant role for the bridge
processes presented. The driven bridge rates are discussed in the context of
background signals in the crystal environment and of implementation methods. We
show that inverse electronic bridge processes quenching the isomeric state
population can improve the performance of a solid-state nuclear clock based on
Th
Effects of state-wide implementation of the Los Angeles Motor Scale for triage of stroke patients in clinical practice
Background: The prehospital identification of stroke patients with large-vessel occlusion (LVO), that should be immediately transported to a thrombectomy capable centre is an unsolved problem. Our aim was to determine whether implementation of a state-wide standard operating procedure (SOP) using the Los Angeles Motor Scale (LAMS) is feasible and enables correct triage of stroke patients to hospitals offering (comprehensive stroke centres, CSCs) or not offering (primary stroke centres, PSCs) thrombectomy.Methods: Prospective study involving all patients with suspected acute stroke treated in a 4-month period in a state-wide network of all stroke-treating hospitals (eight PSCs and two CSCs). Primary endpoint was accuracy of the triage SOP in correctly transferring patients to CSCs or PSCs. Additional endpoints included the number of secondary transfers, the accuracy of the LAMS for detection of LVO, apart from stroke management metrics.Results: In 1123 patients, use of a triage SOP based on the LAMS allowed triage decisions according to LVO status with a sensitivity of 69.2% (95% confidence interval (95%-CI): 59.0-79.5%) and a specificity of 84.9% (95%-CI: 82.6-87.3%). This was more favourable than the conventional approach of transferring every patient to the nearest stroke-treating hospital, as determined by geocoding for each patient (sensitivity, 17.9% (95%-CI: 9.4-26.5%); specificity, 100% (95%-CI: 100-100%)). Secondary transfers were required for 14 of the 78 (17.9%) LVO patients. Regarding the score itself, LAMS detected LVO with a sensitivity of 67.5% (95%-CI: 57.1-78.0%) and a specificity of 83.5% (95%-CI: 81.0-86.0%).Conclusions: State-wide implementation of a triage SOP requesting use of the LAMS tool is feasible and improves triage decision-making in acute stroke regarding the most appropriate target hospital.</p
Urological cancer care pathways: development and use in the context of systematic reviews and clinical practice guidelines
Background: Making healthcare treatment decisions is a complex process involving a broad stakeholder base including patients, their families, health professionals, clinical practice guideline developers and funders of healthcare. Methods: This paper presents a review of a methodology for the development of urological cancer care pathways (UCAN care pathways), which reflects an appreciation of this broad stakeholder base. The methods section includes an overview of the steps in the development of the UCAN care pathways and engagement with clinical content experts and patient groups. Results: The development process is outlined, the uses of the urological cancer care pathways discussed and the implications for clinical practice highlighted. The full set of UCAN care pathways is published in this paper. These include care pathways on localised prostate cancer, locally advanced prostate cancer, metastatic prostate cancer, hormone-resistant prostate cancer, localised renal cell cancer, advanced renal cell cancer, testicular cancer, penile cancer, muscle invasive and metastatic bladder cancer and non-muscle invasive bladder cancer. Conclusion: The process provides a useful framework for improving urological cancer care through evidence synthesis, research prioritisation, stakeholder involvement and international collaboration. Although the focus of this work is urological cancers, the methodology can be applied to all aspects of urology and is transferable to other clinical specialties.11 page(s
Kriterien für die Auswahl einer Softwarelösung für den Betrieb eines Repositoriums für Forschungsdaten
Die öffentliche Bereitstellung von Forschungsdaten zur Nachnutzung im Sinne von Open Science ist Bestandteil des Lebenszyklus von Forschungsdaten und erlangt zunehmende Relevanz. Eine zitierbare Veröffentlichung dieser Daten zeugt von einer transparenten Forschung, belegt die Forschungsleistung eines Forschenden sowie der jeweiligen Einrichtung und macht Forschung reproduzierbar und damit überprüfbar. Forschungsförderer erwarten bereits bei der Antragstellung die Dokumentation und Planung eines umsichtigen und nachhaltigen Umgangs mit Forschungsdaten, bspw. in Form eines Datenmanagementplans, der unter anderem Angaben zu geplanten Lizenzen für Forschungsdaten, Rechten an Daten etc. enthält. Die Umsetzung des Datenmanagementplans ist ein kontinuierlicher Prozess im Laufe eines Projekts und nicht auf eine Datenveröffentlichung zum Projektende hin beschränkt. Der Umgang mit Forschungsdaten wird unter anderem in den Richtlinien Guter Wissenschaftlicher Praxis[1], den Open-Access-Policies von Hochschulen, Forschungsinstituten und Forschungsförderern sowie in den “Data Policies” von Zeitschriften adressiert. Repositorien bilden das technische Grundgerüst für das Forschungsdatenmanagement, da sie den gesamten Prozess von der Übernahme über die Qualitätskontrolle bis hin zur zitierfähigen Veröffentlichung unterstützen. Softwarelösungen für Repositorien sind für unterschiedliche Zwecke und Einsatzszenarien verfügbar. Zu den verbreitetsten zählen beispielsweise Fedora, DSpace, MyCoRe, Islandora, EPrints, Dataverse, Rosetta, Archivematica und Invenio. Die Bestimmung von Kriterien für die Auswahl eines Repositoriums ist nicht trivial und es müssen neben Aspekten der Wirtschaftlichkeit, Skalierbarkeit und Funktionalität noch weitere Kriterien wie die Dokumentation, Verbreitung, Entwicklungsperspektive sowie das Daten- und Lizenzmodell berücksichtigt werden. Der Aufwand für die Erarbeitung eines Kriterienkatalogs darf nicht unterschätzt werden. Im Folgenden bezeichnet Repositorium eine Softwarelösung, die - eingebettet in eine Organisationsstruktur und gegebenenfalls im Kontext weiterer Systeme - Forschungsdaten übernimmt, verwaltet und publiziert. Daraus ergeben sich zwangsläufig Abhängigkeiten zur betreibenden organisatorischen Einheit und der grundlegenden technischen Infrastruktur für den Betrieb der Software und die Speicherung der Daten. In diesem Artikel werden verschiedene Aspekte präsentiert, die für den Auswahlprozess potentiell relevant sind. [1] Siehe auch Kodex der DFG zur guten wissenschaftlichen Praxis: https://www.dfg.de/foerderung/grundlagen_rahmenbedingungen/gwp
Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector
A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements
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Research and Design of a Routing Protocol in Large-Scale Wireless Sensor Networks
无线传感器网络,作为全球未来十大技术之一,集成了传感器技术、嵌入式计算技术、分布式信息处理和自组织网技术,可实时感知、采集、处理、传输网络分布区域内的各种信息数据,在军事国防、生物医疗、环境监测、抢险救灾、防恐反恐、危险区域远程控制等领域具有十分广阔的应用前景。 本文研究分析了无线传感器网络的已有路由协议,并针对大规模的无线传感器网络设计了一种树状路由协议,它根据节点地址信息来形成路由,从而简化了复杂繁冗的路由表查找和维护,节省了不必要的开销,提高了路由效率,实现了快速有效的数据传输。 为支持此路由协议本文提出了一种自适应动态地址分配算——ADAR(AdaptiveDynamicAddre...As one of the ten high technologies in the future, wireless sensor network, which is the integration of micro-sensors, embedded computing, modern network and Ad Hoc technologies, can apperceive, collect, process and transmit various information data within the region. It can be used in military defense, biomedical, environmental monitoring, disaster relief, counter-terrorism, remote control of haz...学位:工学硕士院系专业:信息科学与技术学院通信工程系_通信与信息系统学号:2332007115216
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