1,327 research outputs found
BORROWING BEHAVIOR UNDER FINANCIAL STRESS BY THE PROPRIETARY FIRM: A THEORETICAL ANALYSIS
This paper extends finance theory under risk to account for borrowing behavior under financial stress conditions. As the financial stress level for the firm increases, the role of credit or unused borrowing capacity changes. With a strong equity position, credit is valued as a reserve to avoid liquidation costs resulting from the sale of fixed assets to meet cash flow obligations. As the financial stress on the firm increases the model demonstrates the firmÂ’s willingness to reduce credit reserves and increase its financial leverage in order to increase its probability of survival. These results are derived in a tractable framework by describing risky alternatives in terms of expected values and variances.Financial Economics,
Use of multiple singular value decompositions to analyze complex intracellular calcium ion signals
We compare calcium ion signaling () between two exposures;
the data are present as movies, or, more prosaically, time series of images.
This paper describes novel uses of singular value decompositions (SVD) and
weighted versions of them (WSVD) to extract the signals from such movies, in a
way that is semi-automatic and tuned closely to the actual data and their many
complexities. These complexities include the following. First, the images
themselves are of no interest: all interest focuses on the behavior of
individual cells across time, and thus, the cells need to be segmented in an
automated manner. Second, the cells themselves have 100 pixels, so that they
form 100 curves measured over time, so that data compression is required to
extract the features of these curves. Third, some of the pixels in some of the
cells are subject to image saturation due to bit depth limits, and this
saturation needs to be accounted for if one is to normalize the images in a
reasonably unbiased manner. Finally, the signals have
oscillations or waves that vary with time and these signals need to be
extracted. Thus, our aim is to show how to use multiple weighted and standard
singular value decompositions to detect, extract and clarify the signals. Our signal extraction methods then lead to simple although
finely focused statistical methods to compare signals
across experimental conditions.Comment: Published in at http://dx.doi.org/10.1214/09-AOAS253 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Phonon-driven ultrafast exciton dissociation at donor-acceptor polymer heterojunctions
A quantum-dynamical analysis of phonon-driven exciton dissociation at polymer
heterojunctions is presented, using a hierarchical electron-phonon model
parameterized for three electronic states and 24 vibrational modes. Two
interfering decay pathways are identified: a direct charge separation, and an
indirect pathway via an intermediate bridge state. Both pathways depend
critically on the dynamical interplay of high-frequency C=C stretch modes and
low-frequency ring-torsional modes. The ultrafast, highly non-equilibrium
dynamics is consistent with time-resolved spectroscopic observations
Balancing Communal Goods and Personal Privacy Under a National Health Informational Privacy Rule
Integration of New Technologies and Alternative Methods in Laboratory-Based Scenarios
In this study, we report a preliminary requirements analysis to recognize needs and possibilities for integrating new technologies and methods for lab-based learning in the field of Industry 4.0 and Internet of Things. To this aim, different scenarios, such as real, remote and virtual labs, are considered to be addressable within an integrated learning environment that focuses on alternative methods (i.e. Serious Games, Self-Regulated and Collaborative Learning) and new technologies (i.e. Open Badges, Mixed Reality and Learning Analytics). To support the design of the laboratory-based learning environment, qualitative interviews were conducted with both expert lecturers and relevant students in the field of engineering, to provide complementary perspectives. These interviews were carried out to analyze the requirements, and to identify possible benefits that relevant stakeholders expect by using these teaching and learning methods and technologies. A qualitative content analysis has been started on the interviews to define which is the perception of the new technologies and teaching methods. The different points of view about technologies and methods coming from expert lecturers’ and relevant students’ interviews are provided
Automated simulation of areal bone mineral density assessment in the distal radius from high-resolution peripheral quantitative computed tomography
SummaryAn automated image processing method is presented for simulating areal bone mineral density measures using high-resolution peripheral quantitative computed tomography (HR-pQCT) in the ultra-distal radius. The accuracy of the method is validated against clinical dual X-ray absorptiometry (DXA). This technique represents a useful reference to gauge the utility of novel 3D quantification methods applied to HR-pQCT in multi-center clinical studies and potentially negates the need for separate forearm DXA measurements.IntroductionOsteoporotic status is primarily assessed by measuring areal bone mineral density (aBMD) using 2D dual X-ray absorptiometry (DXA). However, this technique does not sufficiently explain bone strength and fracture risk. High-resolution peripheral quantitative computed tomography (HR-pQCT) has been introduced as a method to quantify 3D bone microstructure and biomechanics. In this study, an automated method is proposed to simulate aBMD measures from HR-pQCT distal radius images.MethodsA total of 117 subject scans were retrospectively analyzed from two clinical bone quality studies. The distal radius was imaged by HR-pQCT and DXA on one of two devices (Hologic or Lunar). Areal BMD was calculated by simulation from HR-pQCT images (aBMD(sim)) and by standard DXA analysis (aBMD(dxa)).ResultsThe reproducibility of the simulation technique was 1.1% (root mean-squared coefficient of variation). HR-pQCT-based aBMD(sim) correlated strongly to aBMD(dxa) (Hologic: R (2) = 0.82, Lunar: R (2) = 0.87), though aBMD(sim) underestimated aBMD(dxa) for both DXA devices (p < 0.0001). Finally, aBMD(sim) predicted aBMD at the proximal femur and lumbar spine with equal power compared to aBMD(dxa).ConclusionThe results demonstrate that aBMD can be simulated from HR-pQCT images of the distal radius. This approach has the potential to serve as a surrogate forearm aBMD measure for clinical HR-pQCT studies when axial bone mineral density values are not required
Quantum Criticality in doped CePd_1-xRh_x Ferromagnet
CePd_1-xRh_x alloys exhibit a continuous evolution from ferromagnetism (T_C=
6.5 K) at x = 0 to a mixed valence (MV) state at x = 1. We have performed a
detailed investigation on the suppression of the ferromagnetic (F) phase in
this alloy using dc-(\chi_dc) and ac-susceptibility (\chi_ac), specific heat
(C_m), resistivity (\rho) and thermal expansion (\beta) techniques. Our results
show a continuous decrease of T_C (x) with negative curvature down to T_C = 3K
at x*= 0.65, where a positive curvature takes over. Beyond x*, a cusp in cac is
traced down to T_C* = 25 mK at x = 0.87, locating the critical concentration
between x = 0.87 and 0.90. The quantum criticality of this region is recognized
by the -log(T/T_0) dependence of C_m/T, which transforms into a T^-q (~0.5) one
at x = 0.87. At high temperature, this system shows the onset of valence
instability revealed by a deviation from Vegard's law (at x_V~0.75) and
increasing hybridization effects on high temperature \chi_dc and \rho.
Coincidentally, a Fermi liquid contribution to the specific heat arises from
the MV component, which becomes dominant at the CeRh limit. In contrast to
antiferromagnetic systems, no C_m/T flattening is observed for x > x_cr rather
the mentioned power law divergence, which coincides with a change of sign of
\beta. The coexistence of F and MV components and the sudden changes in the T
dependencies are discussed in the context of randomly distributed magnetic and
Kondo couplings.Comment: 11 pages, 11 figure
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