6,803 research outputs found
UNTERSUCHUNGEN UBER DIE ABGRENZUNG VON PLEIOTROPIE UND ABSOLUTER KOPPELUNG. EUR 1689.d = INVESTIGATION OF THE EXCLUSION OF PLEIOTROPY AND ABSOLUTE COUPLING. EUR 1689.d
Der Einfluss der Penetranzverhältnisse mutierter Gene auf die Leistungsfähigkeit von Positivmutanten. EUR 2510. = Influence of penetrance of mutant genes on the capacity of positive mutants. EUR 2510.
Nuclear halo of a 177 MeV proton beam in water: theory, measurement and parameterization
The dose distribution of a monoenergetic pencil beam in water consists of an
electromagnetic "core", a "halo" from charged nuclear secondaries, and a much
larger "aura" from neutral secondaries. These regions overlap, but each has
distinct spatial characteristics.
We have measured the core/halo using a 177MeV test beam offset in a water
tank. The beam monitor was a fluence calibrated plane parallel ionization
chamber (IC) and the field chamber, a dose calibrated Exradin T1, so the dose
measurements are absolute (MeV/g/p). We performed depth-dose scans at ten
displacements from the beam axis ranging from 0 to 10cm. The dose spans five
orders of magnitude, and the transition from halo to aura is clearly visible.
We have performed model-dependent (MD) and model-independent (MI) fits to the
data. The MD fit separates the dose into core, elastic/inelastic nuclear,
nonelastic nuclear and aura terms, and achieves a global rms measurement/fit
ratio of 15%. The MI fit uses cubic splines and the same ratio is 9%.
We review the literature, in particular the use of Pedroni's parametrization
of the core/halo. Several papers improve on his Gaussian transverse
distribution of the halo, but all retain his T(w), the radial integral of the
depth-dose multiplying both the core and halo terms and motivating measurements
with large "Bragg peak chambers" (BPCs).
We argue that this use of T(w), which by its definition includes energy
deposition by nuclear secondaries, is incorrect. T(w) should be replaced in the
core term, and in at least part of the halo, by a purely electromagnetic mass
stopping power. BPC measurements are unnecessary, and irrelevant to
parameterizing the pencil beam.Comment: 55 pages, 4 tables, 29 figure
Quantitative Pigmentuntersuchungen an strahleninduzierten Chlorophyllmutanten von Pisum sativum: I. die Letalmutanten. EUR 947-1. = Quantitative studies on pigment in radiation-induced chlorophyll mutations of Pisum sativum: I. Lethal mutations. EUR 947-1.
Quantitative Pigmentuntersuchungen an strahleninduzierten Chlorophyllmutanten von Pisum sativum: II. die fertilen und sterilen Chlorophyllmutanten. EUR 947-2. = Quantitative studies on pigment in radiation-induced chlorophyll mutations of Pisum sativum: II. the fertile and sterile chlorophyll mutations. EUR 947-2.
Opportunities for Improving the Drug Development Process: Results from a Survey of Industry and the FDA
In the United States, the Food and Drug Administration (FDA) agency is responsible for regulating the safety and efficacy of biopharmaceutical drug products. Furthermore, the FDA is tasked with speeding new medical innovations to market. These two missions create an inherent tension within the agency and between the agency and key stakeholders. Oftentimes, communications and interactions between regulated companies and the FDA suffer. The focus of this research is on the interactions between the FDA and the biopharmaceutical companies that perform drug R&D. To assess the current issues and state of communication and interaction between the FDA and industry, we carried out a survey of industry leadership in R&D and regulatory positions as well as senior leadership at the FDA who have responsibility for drug evaluation and oversight. Based on forty-nine industry and eight FDA interviews we conducted, we found that industry seeks additional structured and informal interactions with the FDA, especially during Phase II of development. Overall, industry placed greater value on additional communication than did the FDA. Furthermore, industry interviewees indicated that they were willing to pay PDUFA-like fees during clinical development to ensure that the FDA could hire additional, well-qualified staff to assist with protocol reviews and decision-making. Based on our survey and discussions, we uncovered several thematic opportunities to improve interactions between the FDA and industry and to reduce clinical development times: 1) develop metrics and goals at the FDA for clinical development times in exchange for PDUFA like fees; 2) establish an oversight board consisting of industry, agency officials, and premier external scientists (possibly at NIH or CDC) to evaluate and audit retrospectively completed and terminated drug projects; and 3) construct a knowledge database that can simultaneously protect proprietary data while allowing sponsor companies to understand safety issues and problems of previously developed/failed drug programs. While profound scientific and medical challenges face the FDA and industry, the first step to reducing development times and associated costs and facilitating innovation is to provide an efficient regulatory process that reduces unnecessary uncertainty and delays due to lack of communication and interaction.
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