891 research outputs found
Neutrinoless Double Beta Decay, the Inverted Hierarchy and Precision Determination of theta(12)
Ruling out the inverted neutrino hierarchy with neutrinoless double beta
decay experiments is possible if a limit on the effective mass below the
minimal theoretically possible value is reached. We stress that this lower
limit depends strongly on the value of the solar neutrino mixing angle: it
introduces an uncertainty of a factor of 2 within its current 3 sigma range. If
an experiment is not background-free, a factor of two in effective mass
corresponds to a combined factor of 16 improvement for the experimental
parameters running time, detector mass, background level and energy resolution.
Therefore, a more precise determination of theta(12) is crucial for the
interpretation of experimental results and the evaluation of the potential and
requirements for future experiments. We give the required half-lifes to exclude
(and touch) the inverted hierarchy regime for all double beta decay isotopes
with a Q-value above 2 MeV. The nuclear matrix elements from 6 different groups
and, if available, their errors are used and compared. We carefully put the
calculations on equal footing in what regards various convention issues. We
also use our compilation of matrix elements to give the reachable values of the
effective mass for a given half-life value.Comment: 26 pages, 6 figures. v2: error corrected (misprint in paper we took a
value from), slightly modifying the result
Optical diffraction for measurements of nano-mechanical bending
Micromechanical transducers such as cantilevers for AFM often rely on optical
readout methods that require illumination of a specific region of the
microstructure. Here we explore and exploit the diffraction effects that have
been previously neglected when modeling cantilever bending measurement
techniques. The illumination of a cantilever end causes an asymmetric
diffraction pattern at the photodetector that significantly affects the
calibration of the signal in the popular optical beam deflection technique
(OBDT). Conditions for optimized linear signals that avoid detection artifacts
conflict with small numerical aperture illumination and narrow cantilevers
which are softer and therefore more sensitive. Embracing diffraction patterns
as a physical measurable allows a richer detection technique that decouples
measurements of tilt and curvature and simultaneously relaxes the requirements
on the alignment of illumination and detector. We show analytical results,
numerical simulations and physiologically relevant experimental data
demonstrating the usefulness of these diffraction features. We offer
experimental design guidelines and identify and quantify possible sources of
systematic error of up to 10% in OBDT. We demonstrate a new nanometre
resolution detection method that can replace OBDT, where Frauenhofer and Bragg
diffraction effects from finite sized and patterned cantilevers are exploited.
Such effects are readily generalized to arrays, and allow transmission
detection of mechanical curvature, enabling in-line instruments. In particular,
a cantilever with a periodic array of slots produces Bragg peaks which can be
analyzed to deduce the cantilever curvature. We highlight the comparative
advantages over OBDT by detecting molecular activity of antibiotic Vancomycin,
with an RMS noise equivalent to less than (1.5 nm), as example of
possible multi-maker bio-assays.Comment: 9 pages, 8 figure
Techniques for the Synthesis of Reversible Toffoli Networks
This paper presents novel techniques for the synthesis of reversible networks
of Toffoli gates, as well as improvements to previous methods. Gate count and
technology oriented cost metrics are used. Our synthesis techniques are
independent of the cost metrics. Two new iterative synthesis procedure
employing Reed-Muller spectra are introduced and shown to complement earlier
synthesis approaches. The template simplification suggested in earlier work is
enhanced through introduction of a faster and more efficient template
application algorithm, updated (shorter) classification of the templates, and
presentation of the new templates of sizes 7 and 9. A novel ``resynthesis''
approach is introduced wherein a sequence of gates is chosen from a network,
and the reversible specification it realizes is resynthesized as an independent
problem in hopes of reducing the network cost. Empirical results are presented
to show that the methods are effective both in terms of the realization of all
3x3 reversible functions and larger reversible benchmark specifications.Comment: 20 pages, 5 figure
Novel splice variants associated with one of the zebrafish dnmt3 genes
BACKGROUND: DNA methylation and the methyltransferases are known to be important in vertebrate development and this may be particularly true for the Dnmt3 family of enzymes because they are thought to be the de novo methyltransferases. Mammals have three Dnmt3 genes; Dnmt3a, Dnmt3b, and Dnmt3L, two of which encode active enzymes and one of which produces an inactive but necessary cofactor. However, due to multiple promoter use and alternative splicing there are actually a number of dnmt3 isoforms present. Six different dnmt3 genes have recently been identified in zebrafish. RESULTS: We have examined two of the dnmt3 genes in zebrafish that are located in close proximity in the same linkage group and we find that the two genes are more similar to each other than they are to the other zebrafish dnmt3 genes. We have found evidence for the existence of several different splice variants and alternative splice sites associated with one of the two genes and have examined the relative expression of these genes/variants in a number of zebrafish developmental stages and tissues. CONCLUSION: The similarity of the dnmt3-1 and dnmt3-2 genes suggests that they arose due to a relatively recent gene duplication event. The presence of alternative splice and start sites, reminiscent of what is seen with the human DNMT3s, demonstrates strong parallels between the control/function of these genes across vertebrate species. The dynamic expression levels of these genes/variants suggest that they may well play a role in early development and this is particularly true for dnmt3-2-1 and dnmt3-1. dnmt3-2-1 is the predominantly expressed form prior to zygotic gene activation whereas dnmt3-1 predominates post zygotic gene activation suggesting a distinct developmental role for each
Interpreting and Reporting Results Based on Patient-Reported Outcomes
AbstractThis article deals with the incorporation of patient-reported outcomes (PROs) into clinical trials and focuses on issues associated with the interpretation and reporting of PRO data. The primary focus and context of this information relates to the evidentiary support and reporting for a labeling or advertising claim of a PRO benefit for a new or approved pharmaceutical product. This manuscript focuses on issues associated with assessing clinical significance and common pitfalls to avoid in presenting results related to PROs. Specifically, the questions addressed by this manuscript involve: What are the best methods to assess clinical significance for PROs? How should investigators present PRO data most effectively in a Food and Drug Administration (FDA) application? In labeling or in a scientific publication? Guidelinesfor interpreting clinical significance of PROs and for comprehensively reporting on the methods, measures and results of clinical trials that incorporate PROs are important for clinicians, regulatory agencies, and most of all to patients. Clear specifications for considering a finding on a PRO measure, as clinically meaningful, need to be determined by instrument developers and psychometricians; they need to be reported for all clinical trials involving PRO end points. Clinical trial reports need to be comprehensive, clear, and sufficient to enable any reader to understand the methods, PRO measures, statistical analysis, and results
Diversified Late Acceptance Search
The well-known Late Acceptance Hill Climbing (LAHC) search aims to overcome
the main downside of traditional Hill Climbing (HC) search, which is often
quickly trapped in a local optimum due to strictly accepting only non-worsening
moves within each iteration. In contrast, LAHC also accepts worsening moves, by
keeping a circular array of fitness values of previously visited solutions and
comparing the fitness values of candidate solutions against the least recent
element in the array. While this straightforward strategy has proven effective,
there are nevertheless situations where LAHC can unfortunately behave in a
similar manner to HC. For example, when a new local optimum is found, often the
same fitness value is stored many times in the array. To address this
shortcoming, we propose new acceptance and replacement strategies to take into
account worsening, improving, and sideways movement scenarios with the aim to
improve the diversity of values in the array. Compared to LAHC, the proposed
Diversified Late Acceptance Search approach is shown to lead to better quality
solutions that are obtained with a lower number of iterations on benchmark
Travelling Salesman Problems and Quadratic Assignment Problems
The planetary data system educational CD-ROM
The Planetary Data System (PDS) is producing a special educational CD-ROM that contains samples of PDS datasets and is expected to be released in 1993. The CD-ROM will provide university-level instructors with PDS-compatible materials and information that can be used to construct student problem sets using real datasets. The main purposes of the CD-ROM are to facilitate wide use of planetary data and to introduce a large community to the PDS. To meet these objectives the Educational CD-ROM will also contain software to manipulate the data, background discussions about scientific questions that can be addressed with the data, and a suite of exercises that illustrate analysis techniques. Students will also be introduced to the SPICE concept, which is a new way of maintaining geometry and instrument information. The exercises will be presented at the freshman through graduate student levels. With simplification, some of the material should also be of use at the high school level
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