707 research outputs found
A high efficiency, low background detector for measuring pair-decay branches in nuclear decay
We describe a high efficiency detector for measuring electron-positron pair
transitions in nuclei. The device was built to be insensitive to gamma rays and
to accommodate high overall event rates. The design was optimized for total
pair kinetic energies up to about 7 MeV.Comment: Accepted for publication by Nucl. Inst. & Meth. in Phys. Res. A (NIM
A
Entrepreneurial Orientation and Firm Performance in the Context of Upper Echelon Theory
Entrepreneurial Orientation (EO) is a firm-level phenomenon, which involves the firm’s prospects to take risks, be proactive, and be innovative. Most of the research assumes a positive EO-performance relationship adopting the EO-as-advantage perspective without providing enough theoretical foundations of the way EO enhances performance. This paper provides insights into the EO and firm performance relationship looking into the EO-as-experimentation perspective. Through EO-as-experimentation perspective, we argue for the importance of looking into the differential effects of each of the EO dimensions on firm performance in active and inactive firms. We hypothesized that the effect of each of the proactiveness and innovativeness dimension of EO on firm performance is positive among active firms and negative among inactive firms. Whereas risk taking dimension of EO is negative among active and inactive firms. Based on the results of firm fixed effect regression some empirical support for the hypotheses is presented and discussed
Effective balancing error and user effort in interactive handwriting recognition
This is the author’s version of a work that was accepted for publication in Pattern Recognition Letters. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Pattern Recognition Letters, Volume 37, 1 February 2014, Pages 135–142 DOI 10.1016/j.patrec.2013.03.010[EN] Transcription of handwritten text documents is an expensive and time-consuming task. Unfortunately, the accuracy of current state-of-the-art handwriting recognition systems cannot guarantee fully-automatic high quality transcriptions, so we need to revert to the computer assisted approach. Although this approach reduces the user effort needed to transcribe a given document, the transcription of handwriting text documents still requires complete manual supervision. An especially appealing scenario is the interactive transcription of handwriting documents, in which the user defines the amount of errors that can be tolerated in the final transcribed document. Under this scenario, the transcription of a handwriting text document could be obtained efficiently, supervising only a certain number of incorrectly recognised words. In this work, we develop a new method for predicting the error rate in a block of automatically recognised words, and estimate how much effort is required to correct a transcription to a certain user-defined error rate. The proposed method is included in an interactive approach to transcribing handwritten text documents, which efficiently employs user interactions by means of active and semi-supervised learning techniques, along with a hypothesis recomputation algorithm based on constrained Viterbi search. Transcription results, in terms of trade-off between user effort and transcription accuracy, are reported for two real handwritten documents, and prove the effectiveness of the proposed approach.The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under Grant agreement No 287755 (transLectures). Also supported by the EC (FEDER, FSE), the Spanish Government (MICINN, MITyC, "Plan E", under grants MIPRCV "Consolider Ingenio 2010", MITTRAL (TIN2009-14633-C03-01), iTrans2 (TIN2009-14511), and FPU (AP2007-02867), and the Generalitat Valenciana (Grants Prometeo/2009/014 and GV/2010/067). Special thanks to Jesus Andres for his fruitful discussions.Serrano Martinez Santos, N.; Civera Saiz, J.; Sanchis Navarro, JA.; Juan Císcar, A. (2014). Effective balancing error and user effort in interactive handwriting recognition. Pattern Recognition Letters. 37(1):135-142. https://doi.org/10.1016/j.patrec.2013.03.010S13514237
Spectroscopy of 13B via the 13C(t,3He) reaction at 115 AMeV
Gamow-Teller and dipole transitions to final states in 13B were studied via
the 13C(t,3He) reaction at Et = 115 AMeV. Besides the strong Gamow-Teller
transition to the 13B ground state, a weaker Gamow-Teller transition to a state
at 3.6 MeV was found. This state was assigned a spin-parity of 3/2- by
comparison with shell-model calculations using the WBP and WBT interactions
which were modified to allow for mixing between nhw and (n+2)hw configurations.
This assignment agrees with a recent result from a lifetime measurement of
excited states in 13B. The shell-model calculations also explained the
relatively large spectroscopic strength measured for a low-lying 1/2+ state at
4.83 MeV in 13B. The cross sections for dipole transitions up to Ex(13B)= 20
MeV excited via the 13C(t,3He) reaction were also compared with the shell-model
calculations. The theoretical cross sections exceeded the data by a factor of
about 1.8, which might indicate that the dipole excitations are "quenched".
Uncertainties in the reaction calculations complicate that interpretation.Comment: 11 pages, 6 figure
The Nd(He,) and Sm(,He) reactions with applications to decay of Nd
The Nd(He,) reaction at 140 MeV/u and Sm(,He)
reaction at 115 MeV/u were measured, populating excited states in Pm.
The transitions studied populate intermediate states of importance for the
(neutrinoless) decay of Nd to Sm. Monopole and
dipole contributions to the measured excitation-energy spectra were extracted
by using multipole decomposition analyses. The experimental results were
compared with theoretical calculations obtained within the framework of
Quasiparticle Random-Phase Approximation (QRPA), which is one of the main
methods employed for estimating the half-life of the neutrinoless
decay () of Nd. The present results thus provide useful
information on the neutrino responses for evaluating the and
matrix elements. The matrix element
calculated from the Gamow-Teller transitions through the lowest state
in the intermediate nucleus is maximally about half of that deduced from the
half-life measured in direct counting experiments and at least
several transitions through intermediate states in Pm are
required to explain the half-life.
Because Gamow-Teller transitions in the Sm(,He) experiment are
strongly Pauli-blocked, the extraction of Gamow-Teller strengths was
complicated by the excitation of the , ,
isovector spin-flip giant monopole resonance (IVSGMR). However, the near
absence of Gamow-Teller transition strength made it possible to cleanly
identify this resonance, and the strength observed is consistent with the full
exhaustion of the non-energy-weighted sum rule for the IVSGMR.Comment: 18 pages, 13 figures, 2 table
An Improved Neutron Electric Dipole Moment Experiment
A new measurement of the neutron EDM, using Ramsey's method of separated
oscillatory fields, is in preparation at the new high intensity source of
ultra-cold neutrons (UCN) at the Paul Scherrer Institute, Villigen, Switzerland
(PSI). The existence of a non-zero nEDM would violate both parity and time
reversal symmetry and, given the CPT theorem, might lead to a discovery of new
CP violating mechanisms. Already the current upper limit for the nEDM
(|d_n|<2.9E-26 e.cm) constrains some extensions of the Standard Model.
The new experiment aims at a two orders of magnitude reduction of the
experimental uncertainty, to be achieved mainly by (1) the higher UCN flux
provided by the new PSI source, (2) better magnetic field control with improved
magnetometry and (3) a double chamber configuration with opposite electric
field directions.
The first stage of the experiment will use an upgrade of the RAL/Sussex/ILL
group's apparatus (which has produced the current best result) moved from
Institut Laue-Langevin to PSI. The final accuracy will be achieved in a further
step with a new spectrometer, presently in the design phase.Comment: Flavor Physics & CP Violation Conference, Taipei, 200
Temporally and Longitudinally Tailored Dynamic Space-Time Wave Packets
In general, space-time wave packets with correlations between transverse
spatial fields and temporal frequency spectra can lead to unique spatiotemporal
dynamics, thus enabling control of the instantaneous light properties. However,
spatiotemporal dynamics generated in previous approaches manifest themselves at
a given propagation distance yet not arbitrarily tailored longitudinally. Here,
we propose and demonstrate a new versatile class of judiciously synthesized
wave packets whose spatiotemporal evolution can be arbitrarily engineered to
take place at various predesigned distances along the longitudinal propagation
path. Spatiotemporal synthesis is achieved by introducing a 2-dimensional
spectrum comprising both temporal and longitudinal wavenumbers associated with
specific transverse Bessel-Gaussian fields. The resulting spectra are then
employed to produce wave packets evolving in both time and axial distance - in
full accord with the theoretical analysis. In this respect, various light
degrees of freedom can be independently manipulated, such as intensity,
polarization, and transverse spatial distribution (e.g., orbital angular
momentum). Through a temporal-longitudinal frequency comb spectrum, we simulate
the synthesis of the aforementioned wave packet properties, indicating a
decrease in relative error compared to the desired phenomena as more spectral
components are incorporated. Additionally, we experimentally demonstrate
tailorable spatiotemporal fields carrying time- and longitudinal-varying
orbital angular momentum, such that the local topological charge evolves every
~1 ps in the time domain and 10 cm axially. We believe that our space-time wave
packets can significantly expand the exploration of spatiotemporal dynamics in
the longitudinal dimension, and potentially enable novel applications in
ultrafast microscopy, light-matter interactions, and nonlinear optics
Inflammatory Response of Ischemic Tolerance in Circulating Plasma : Preconditioning-Induced by Transient Ischemic Attack (TIA) Phenomena in Acute Ischemia Patients (AIS)
Ischemic tolerance (IT) refers to a state where cells are resistant to the damaging effects caused by periods of ischemia. In a clinical scenario, the IT phenomenon would be activated by a recent transient ischemic attack (TIA) before an ischemic stroke (IS). The characterization of inflammatory protein expression patterns will contribute to improved understanding of IT. A total of 477 IS patients from nine hospitals, recruited between January 2011 and January 2016, were included in the current study and divided in three groups: 438 (91.9%) patients without previous TIA (group 1), 22 (4.6%) patients who suffered TIA 24 h before IS (group 2), and 17 (3.5%) patients who suffered TIA between 24 h and 7 days prior to IS (group 3). An inflammatory biomarker panel (IL-6, NT-proBNP, hsCRP, hs-Troponin, NSE, and S-100b) on plasma and a cytokine antibody array was performed to achieve the preconditioning signature potentially induced by TIA phenomena. Primary outcome was modified rankin scale (mRs) score at 90 days. Recent previous TIA was associated with better clinical outcome at 90 days (median mRS of group 1: 2.0 [1.0-4.0]; group 2: 2.0 [0.0-3.0]; group 3: 1.0 [0-2.5]; p = 0.086) and smaller brain lesion (group 1: 3.7 [0.7-18.3]; group 2: 0.8 [0.3-8.9]; group 3: 0.6 [0.1-5.5] mL; p = 0.006). All inflammation biomarkers were down regulated in the groups of recent TIA prior to IS compared to those who did not suffer a TIA events. Moreover, a cytokine antibody array revealed 30 differentially expressed proteins between the three groups. Among them, HRG1-alpha (Fold change 74.4 between group 1 and 2; 74.2 between group 1 and 3) and MAC-1 (Fold change 0.05 between group 1 and 2; 0.06 between group 1 and 3) expression levels would better stratify patients with TIA 7 days before IS. These two proteins showed an earlier inflammation profile that was not detectable by the biomarker panel. Inflammatory pathways were activated by transient ischemic attack, however the period of time between this event and a further ischemic stroke could be determined by a protein signature that would contribute to define the role of ischemic tolerance induced by TIA
Q^2 Dependence of the S_{11}(1535) Photocoupling and Evidence for a P-wave resonance in eta electroproduction
New cross sections for the reaction are reported for total
center of mass energy =1.5--2.3 GeV and invariant squared momentum transfer
=0.13--3.3 GeV. This large kinematic range allows extraction of new
information about response functions, photocouplings, and coupling
strengths of baryon resonances. A sharp structure is seen at 1.7 GeV.
The shape of the differential cross section is indicative of the presence of a
-wave resonance that persists to high . Improved values are derived for
the photon coupling amplitude for the (1535) resonance. The new data
greatly expands the range covered and an interpretation of all data with
a consistent parameterization is provided.Comment: 31 pages, 9 figure
Light Vector Mesons in the Nuclear Medium
The light vector mesons (, , and ) were produced in
deuterium, carbon, titanium, and iron targets in a search for possible
in-medium modifications to the properties of the meson at normal nuclear
densities and zero temperature. The vector mesons were detected with the CEBAF
Large Acceptance Spectrometer (CLAS) via their decays to . The rare
leptonic decay was chosen to reduce final-state interactions. A combinatorial
background was subtracted from the invariant mass spectra using a
well-established event-mixing technique. The meson mass spectrum was
extracted after the and signals were removed in a nearly
model-independent way. Comparisons were made between the mass spectra
from the heavy targets () with the mass spectrum extracted from the
deuterium target. With respect to the -meson mass, we obtain a small
shift compatible with zero. Also, we measure widths consistent with standard
nuclear many-body effects such as collisional broadening and Fermi motion.Comment: 15 pages, 18 figures, 3 table
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