Reflective Ghost Imaging through Turbulence

Recent work has indicated that ghost imaging may have applications in standoff sensing. However, most theoretical work has addressed transmission-based ghost imaging. To be a viable remote-sensing system, the ghost imager needs to image rough-surfaced targets in reflection through long, turbulent optical paths. We develop, within a Gaussian-state framework, expressions for the spatial resolution, image contrast, and signal-to-noise ratio of such a system. We consider rough-surfaced targets that create fully developed speckle in their returns, and Kolmogorov-spectrum turbulence that is uniformly distributed along all propagation paths. We address both classical and nonclassical optical sources, as well as a computational ghost imager.Comment: 13 pages, 3 figure

A dynamical time operator in Dirac's relativistic quantum mechanics

A self-adjoint dynamical time operator is introduced in Dirac's relativistic formulation of quantum mechanics and shown to satisfy a commutation relation with the Hamiltonian analogous to that of the position and momentum operators. The ensuing time-energy uncertainty relation involves the uncertainty in the instant of time when the wave packet passes a particular spatial position and the energy uncertainty associated with the wave packet at the same time, as envisaged originally by Bohr. The instantaneous rate of change of the position expectation value with respect to the simultaneous expectation value of the dynamical time operator is shown to be the phase velocity, in agreement with de Broglie's hypothesis of a particle associated wave whose phase velocity is larger than c. Thus, these two elements of the original basis and interpretation of quantum mechanics are integrated into its formal mathematical structure. Pauli's objection is shown to be resolved or circumvented. Possible relevance to current developments in interference in time, in Zitterbewegung like effects in spintronics, grapheme and superconducting systems and in cosmology is noted

MIMO free-space optical communication employing subcarrier intensity modulation in atmospheric turbulence channels

In this paper, we analyse the error performance of transmitter/receiver array free-space optical (FSO) communication system employing binary phase shift keying (BPSK) subcarrier intensity modulation (SIM) in clear but turbulent atmospheric channel. Subcarrier modulation is employed to eliminate the need for adaptive threshold detector. Direct detection is employed at the receiver and each subcarrier is subsequently demodulated coherently. The effect of irradiance fading is mitigated with an array of lasers and photodetectors. The received signals are linearly combined using the optimal maximum ratio combining (MRC), the equal gain combining (EGC) and the selection combining (SelC). The bit error rate (BER) equations are derived considering additive white Gaussian noise and log normal intensity fluctuations. This work is part of the EU COST actions and EU projects

Conveyor belt clock synchronization

A protocol for synchronizing distant clocks is proposed that does not rely on the arrival times of the signals which are exchanged, and an optical implementation based on coherent-state pulses is described. This protocol is not limited by any dispersion that may be present in the propagation medium through which the light signals are exchanged. Possible improvements deriving from the use of quantum-mechanical effects are also addressed.Comment: 8 pages, 7 figure

Transforming Data into Action: Fostering College Success for Single Mothers and Parenting Students

Transforming Data into Action describes the accomplishments of the eight colleges that participated in College Success for Single Mothers, a three-year project that NCTN launched in January 2020. The goal of the project was to increase colleges' capacity to collect data to identify parenting students, with particular attention to single mothers students, and use that data to address their needs through the implementation of targeted action plans. Each college is transforming data into action to better support student parents' success and improve and sustain systems for ongoing data collection and use. Transforming Data into Action offers insights into what made colleges successful in their efforts. The report contributes to the limited body of research literature and practical guidance for colleges on successful approaches to improving the conditions and outcomes for parenting students

From Music to Museum: Applications of Multi-Objective Ant Colony Systems to Real World Problems

International audienceRecommender systems are a flourishing domain in computer science for almost 30 years now. This rising popularity follows closely the number of data collected all around the world. Each and every internet user produces a huge amount of content during his lifetime. Recommender systems proactively help users to navigate these pieces of information by gathering, and selecting the items to users' needs. In this paper, we discuss the possibility and interest of applying our Multi-Objective Ant Colony System called AntRS to recommend items in different application domains. In particular, we show how our model performs better than the state-of-the-art models with music dataset, and describe our work-in-progress with the museum of fine arts in Nancy (France). The motivation behind this change of application domain is the recommendation of progressive sequences rather than unordered lists of items

Einfluss von Erythropoietin auf die Frakturheilung im murinen Ischämiemodell

Einfluss von Erythropoietin auf die Frakturheilung im murinen Ischämiemodell Erythropoietin (EPO) fördert die Blutbildung im Knochenmark und stimuliert die Angiogenese über die Expression von Wachstumsfaktoren wie VEGF (Vascular Endothelial Growth Factor). Verschiedene Studien konnten bereits zeigen, dass die Behandlung mit EPO die Frakturheilung verbessert. Dies ist wahrscheinlich auf die erhöhte Expression von angiogenen Wachstumsfaktoren im Kallus zurückzuführen. Ziel dieser Studie war es daher, den Einfluss von EPO auf die Frakturheilung im ischämischen Mausmodell zu untersuchen. Insgesamt wurden für die Studie 45 CD-1 Mäuse untersucht. Die Ischämie wurde durch die Ligatur der Arteria femoralis superficialis im Bereich der rechten unteren Extremität induziert. Anschließend wurden die Femora geschlossen frakturiert und mit einer intramedullären Kompressionsschraube osteosynthetisch versorgt. Den Tieren wurden täglich 500 IE/kg Körpergewicht EPO intraperitoneal appliziert. Die Kontrollgruppe erhielt die äquivalente Menge Kochsalzlösung. 2 und 5 Wochen postoperativ wurden die Knochen biomechanisch, histologisch, radiologisch (Röntgen, Micro-Computertomographie) sowie mittels Western Blot untersucht. Biomechanisch zeigte sich nach Gabe von EPO 5 Wochen postoperativ eine signifikant höhere Biegesteifigkeit im Vergleich zur Kontrolle. Histologisch konnte sowohl nach 2 Wochen als auch nach 5 Wochen ein signifikant höherer Anteil an Knochengewebe und ein geringerer Anteil an Bindegewebe im Kallus nachgewiesen werden. In der CT-Auswertung zeigte sich 2 Wochen postoperativ nach Gabe von EPO ein größeres Knochenvolumen im Vergleich zur Kontrollgruppe. In den Western Blot Untersuchungen zeigte sich im Kallus der mit EPO behandelten Tiere eine höhere Expression des angiogenen Wachstumsfaktors CYR61 (Cysteine-rich angiogenic inducer 61) sowie von OPG (Osteoprotegerin) und RANKL (Receptor Activator of NF-κB Ligand). Interessanterweise hatte die Behandlung mit EPO keinen signifikanten Einfluss auf die Expression von VEGF. Zusammenfassend lässt sich sagen, dass die Behandlung mit Erythropoietin den Remodelingprozess beschleunigt und die Frakturheilung signifikant verbessert.The influence of erythropoietin on fracture healing in an ischemic murine model Erythropoietin (EPO) induces hematopoiesis in the bone marrow and stimulates angiogenesis through expression of different growth factors. Former studies could show that the treatment with EPO improves fracture healing. This might be due to an increased expression of angiogenic growth factors in the fracture callus. Therefore, we studied the influence of EPO on fracture healing in an ischemic murine fracture model. In this study, a total number of 45 CD-1 mice were used. Ischemia was induced through a ligature of the profound femoral artery in the lower right extremity. A closed fracture of the femora was created and stabilized using an intramedullary compression screw. The animals received 500 IE/kg bodyweight EPO intraperitoneally daily. The control group received an equivalent amount of saline solution. 2 and 5 weeks after fracture, the bones were analyzed using biomechanical, histological, radiological (x-ray, Micro-CT) and Western Blot methods. Biomechanical analysis at 5 weeks after fracture showed a significantly higher bending stiffness after treatment with EPO compared to the control group. Histologically, the amount of bone tissue was significantly higher and the amount of fibrous tissue was significantly reduced in the EPO treated animals 2 and 5 weeks after fracture. The micro-CT-analysis showed also a higher bone volume in the callus after EPO treatment at 2 weeks after fracture compared to the controls. The Western Blot analysis showed a higher expression of the angiogenic growth factor CYR61 (Cysteine-rich angiogenic inducer 61) and OPG (Osteoprotegerin) / RANKL (Receptor Activator of NF-κB Ligand). Interestingly, EPO did not effect the expression of VEGF (Vascular Endothelial Growth Factor). In conclusion, the treatment with EPO accelerates the remodeling process and improves fracture healing in an ischemic fracture model

Fragility Fractures of the Pelvic Ring: Analysis of Epidemiology, Treatment Concepts, and Surgical Strategies from the Registry of the German Pelvic Multicenter Study Group

Background: Fragility fractures of the pelvic ring (FFPs) represent a fast-growing entity in geriatric traumatology with increasing incidence worldwide. This study aimed to analyze the epidemiology, treatment concepts, and surgical strategies for FFPs based on data collected by the German Pelvic Multicenter Study Group documented in the German Pelvic Fracture Registry. It is the largest cohort study of its kind. Methods: This retrospective cohort study included patients aged 65 years or older after FFPs, as classified according to the Rommens and Hofmann classification. Data were collected from July 2018 onward and analyzed for demographics; fracture classifications; treatment modalities (operative vs. non-operative); and details of surgery, including timing and choice of implants. Patients after high-energy trauma were excluded. Statistical analyses included descriptive metrics and subgroup comparisons. Results: Among 1242 patients (84% female; median age 83.4 years), FFP Type II was the most common fracture type (50.8%), followed by Type IV (21.1%). Non-operative management was employed in 68.8% of cases, while 30.9% underwent surgery. Surgical intervention was more frequent in higher-grade FFPs (e.g., 72.1% in Type IV). The most common surgical technique for the posterior pelvic ring was percutaneous screw fixation (61.3%), with navigation used in 47.4% of cases. Conclusions: This study highlights the variability in treatment strategies for FFPs, with conservative management predominating in lower-grade fractures and surgical approaches increasingly utilized for more complex cases. The findings underscore the need for standardized, evidence-based guidelines and further research to optimize treatment and long-term outcomes for geriatric patients with FFPs

A novel minimally invasive and press-fit method for symphysiodesis - a biomechanical analysis

Purpose Does the cylindrical shaped bone block allow a stable construct for the arthrodesis of the pubic symphysis compared to a rectangular shaped bone block. The cylindrical shaped bone block stabilized by a 3.5 symphyseal plate is inferior to the stabilization with an internal fxator. Methods This study analyzed the arthrodesis of the pubic symphysis on 24 synthetic pelvises, using a rectangular shaped bone block (control group) or a cylindrical shaped bone block, stabilized with a symphysis locking plate (n=8) as the standard clinical procedure. Additionally we analyzed the stability using an internal fxator. Results This study showed that utilizing a cylindrical shaped synthetic bone graft results in a signifcant higher contact area and compression force compared to the classical rectangular shaped graft. Furthermore, the stabilization with an internal fxator had the tendency for increases of compression force and contact area, yet without a statistical signifcance, when compared to the plate fxation. Conclusion The novel method of cylindrical symphysis resection and cylindrical bone block implantation allowed an increased biomechanical stability compared to using a classical rectangular bone graft, also resulting in higher contact area. Moreover, this technique would also allow a minimally invasive approach for this purpose, which in turn could preserve perisymphyseal ligaments, thereby improving healing in a clinical context