714 research outputs found
Federal Employee Invention Rights - Time to Legislate
It is the purpose of this article to review judicial standards applicable to the determination of rights in inventions made by employees of the federal government, to note statutory provisions affecting the problem, to examine the content and effect of the present Executive program for determining such rights, to review and evaluate two fundamental and conflicting theories in this field, and to propose legislation establishing appropriate standards and procedures. This topic is believed to have general interest because, in addition to the urgencies suggested above, the problem touches some of the basic legal philosophy underlying the United States patent system
SPAD based imaging of Cherenkov light in radiation therapy
During radiotherapy, X-ray beams induce Cherenkov light emission in tissue as part of the dose delivery. This light can be used for dosimetry, in order to track and image the dose as it happens. The Cherenkov light levels are in the range of 10−6 to 10−9 W∕cm2, which makes it challenging to detect in a clinical environment. However, because the radiation is pulsed in 4 microsecond bursts, time-gated acquisition of the signal allows for robust detection, even in the presence of ambient room lighting. Thus, imaging sensors for this application must be highly sensitive and must be able to time gate faster than a microsecond. In this study, the use of a solid-state detector composed of 64x32 single photon avalanche diodes (SPAD) was examined. The advantages of this technology were intra-chip amplification, superior X-ray noise rejection, and fast temporal gating of the acquisition. The results show that the SPAD camera was sensitive enough to detect Cherenkov radiation despite the 3% fill factor. 2D oversampling (x25) was also used to increase final image resolution to 320x160. In this work we demonstrate the SPAD camera performance in imaging Cherenkov emission from a tissue optical phantom and one patient undergoing radiotherapy. The SPAD camera sensors could be a viable alternative for Cherenkov imaging, as compared to current imaging methods that are mostly focused around image intensifier-based cameras and so have a range of non-linearities and instabilities which could be solved by an all solid-state camera sensor.
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Rethinking Supply Chains as Neighborhoods
This paper explores the implication of a neighborhood model for interfirm interactions that explicitly tries to create an equality matching relationship among firms in an industry. The aim is to examine what would happen if these firms worked to gain trust with each other with an eye toward maximizing the value of the collaboration across projects rather than just maximizing revenues in individual projects. A review of extant literature and an analysis of in-depth interviews yielded three actionable strategies that support the creation of a sustainable neighborhood in the construction industry: 1) Hub Strategy, 2) Trust Exercise Strategy, and 3) Sustainable Neighborhood Strategy. As envisioned in this study, the hub is a concentrated, inter-organizational structure for supply chain participants in large, complex projects. Importantly, hub members engage in a variety of technical activities that infuse ongoing and future projects with innovation, scope optimization, and operational efficiencies. Additionally, other activities within the hub are designed to purposefully allow participants to develop trust through collaboration before or outside of their primary contractual engagements. At present, this model has been examined for construction megaprojects, but the general neighborhood concept could be applied to many different industries and settings including manufacturing supply chains and collaborations among communities engaging in economic development. Future work will explore whether mechanisms like the hub and trust exercises can be applied in these other settings as well.IC2 Institut
EUS-guided verteporfin photodynamic therapy for pancreatic cancer
BACKGROUND AND AIMS: Locally advanced pancreatic cancer (LAPC) often causes obstruction. Verteporfin photodynamic therapy (PDT) can feasibly "debulk" tumor more safely than noncurative surgery and has multiple advantages over older PDT agents. We aimed to assess the feasibility of EUS-guided verteporfin PDT in ablating nonresectable LAPC. METHODS: Adults with LAPC with adequate biliary drainage were prospectively enrolled. Exclusion criteria included significant metastatic disease burden, disease involving >50% duodenal or major artery circumference, and recent treatment with curative intent. CT was obtained between day -28 to 0. On day 0, verteporfin 0.4 mg/kg was infused 60 to 90 minutes before EUS, during which a diffuser was positioned in the tumor and delivered light at 50 J/cm for 333 seconds. CT was obtained on day 2, with adverse event monitoring occurring on days 1, 2, and 14. Primary outcome was presence of necrosis. RESULTS: Of 8 patients (62.5% male, mean age 65±7.9 y) included in the study, 5 were staged at T3, 2 at T2, and 1 at T1. Most (4) had primary lesions in the pancreatic head. Mean pretrial tumor diameter was 33.3±13.4 mm. On day 2 CT, 5 lesions demonstrated a zone of necrosis measuring a mean diameter of 15.7±5.5 mm; 3 cases did not develop necrosis. No adverse events were noted during the procedure or postprocedure observation period (day 1-3), and no changes in patient reported outcomes were noted. CONCLUSIONS: In this pilot study, EUS-guided verteporfin PDT is feasible and shows promise as a minimally invasive ablative therapy for LAPC in select patients. Tumor necrosis is visible within 48 hours after treatment. Patient enrollment and data collection are ongoing
Noninvasive Fluorescence Monitoring of Protoporphyrin IX Production and Clinical Outcomes in Actinic Keratoses Following Short-Contact Application of 5-Aminolevulinate
Topical 5-aminolevulinic acid (ALA) is widely used in photodynamic therapy (PDT) of actinic keratoses (AK), a type of premalignant skin lesion. However, the optimal time between ALA application and exposure to light has not been carefully investigated. Our objective is to study the kinetics of protoporphyrin IX (PpIX) accumulation in AK after short contact ALA and relate this to erythemal responses. Using a noninvasive dosimeter, PpIX fluorescence measurements (5 replicates) were taken at 20-min intervals for 2 h following ALA application, in 63 AK in 20 patients. Data were analyzed for maximal fluorescent signal obtained, kinetic slope, and changes in erythema. Our results show that PpIX accumulation was linear over time, becoming statistically higher than background in 48% of all lesions by 20 min, 92% of lesions by 1 h, and 100% of lesions by 2 h. PpIX accumulation was roughly correlated with changes in lesional erythema post-PDT. We conclude that significant amounts of PpIX are produced in all AK lesions by 2 h. The linear kinetics of accumulation suggest that shorter ALA application times may be efficacious in many patients. Noninvasive fluorescence monitoring of PpIX may be useful to delineate areas of high PpIX accumulation within precancerous areas of the skin
Criteria for the design of tissue-mimicking phantoms for the standardization of biophotonic instrumentation
A lack of accepted standards and standardized phantoms suitable for the technical validation of biophotonic instrumentation hinders the reliability and reproducibility of its experimental outputs. In this Perspective, we discuss general criteria for the design of tissue-mimicking biophotonic phantoms, and use these criteria and state-of-the-art developments to critically review the literature on phantom materials and on the fabrication of phantoms. By focusing on representative examples of standardization in diffuse optical imaging and spectroscopy, fluorescence-guided surgery and photoacoustic imaging, we identify unmet needs in the development of phantoms and a set of criteria (leveraging characterization, collaboration, communication and commitment) for the standardization of biophotonic instrumentation
Multiple Projection Optical Diffusion Tomography with Plane Wave Illumination
We describe a new data collection scheme for optical diffusion tomography in
which plane wave illumination is combined with multiple projections in the slab
imaging geometry. Multiple projection measurements are performed by rotating
the slab around the sample. The advantage of the proposed method is that the
measured data can be much more easily fitted into the dynamic range of most
commonly used detectors. At the same time, multiple projections improve image
quality by mutually interchanging the depth and transverse directions, and the
scanned (detection) and integrated (illumination) surfaces. Inversion methods
are derived for image reconstructions with extremely large data sets. Numerical
simulations are performed for fixed and rotated slabs
Scattering phase Function Spectrum Makes Reflectance Spectrum Measured from Intralipid phantoms and Tissue Sensitive to the Device Detection Geometry
Reflectance spectra measured in Intralipid (IL) close to the source are sensitive to wavelength -dependent changes in reduced scattering coefficient (μs′)and scattering phase function (PF). Experiments and simulations were performed using device designs with either single or separate optical fibers for delivery and collection of light in varying concentrations of IL. Spectral reflectance is not consistentl y linear with varying IL concentration, with PF -dependent effects observed for single fiber devices with diameters smaller than ten transport lengths and for separate source- detector devices that collected light at less than half of a transport length from the source. Similar effects are thought to be seen in tissue, limiting the ability to quantitatively compare spectra from different devices without compensation
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