1,892 research outputs found
A Computer Algorithm For Engineering Off-Shell Multiplets With Four Supercharges On The World Sheet
We present an adinkra-based computer algorithm implemented in a Mathematica
code and use it in a limited demonstration of how to engineer off-shell,
arbitrary N-extended world-sheet supermultiplets. Using one of the outputs from
this algorithm, we present evidence for the unexpected discovery of a
previously unknown 8 - 8 representation of N = 2 world sheet supersymmetry. As
well, we uncover a menagerie of (p, q) = (3, 1) world sheet supermultiplets.Comment: 52 pages, 64 figures, LaTeX twice, added note in proof, addition of
comments about gauge invariance for 4D vector & tensor supermultiplet
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,
Impact of glucuronide interferences on therapeutic drug monitoring of posaconazole by tandem mass spectrometry
Background: Posaconazole is a novel antifungal drug for oral application intended especially for therapy of invasive mycoses. Due to variable gastrointestinal absorption, adverse side effects, and suspected drug-drug interactions, therapeutic drug monitoring (TDM) of posaconazole is recommended. Method: A fast ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for quantification of posaconazole with a run-time <3 min was developed and compared to a LC-MS/MS method and HPLC method with fluorescence detection. Results: During evaluation of UPLC-MS/MS, two earlier eluting peaks were observed in the MRM trace of posaconazole. This was only seen in patient samples, but not in spiked calibrator samples. Comparison with LC-MS/MS disclosed a significant bias with higher concentrations measured by LC-MS/MS, while UPLC-MS/MS showed excellent agreement with the commercially available HPLC method. In the LC-MS/MS procedure, comparably wide and left side shifted peaks were noticed. This could be ascribed to in-source fragmentation of conjugate metabolites during electrospray ionisation. Precursor and product ion scans confirmed the assumption that the additional compounds are posaconazole glucuronides. Reducing the cone voltage led to disappearance of the glucuronide peaks. Slight modification of the LC-MS/MS method enabled separation of the main interference, leading to significantly reduced deviation. Conclusions: These results highlight the necessity to reliably eliminate interference from labile drug metabolites for correct TDM results, either by sufficient separation or selective MS conditions. The presented UPLC-MS/MS method provides a reliable and fast assay for TDM of posaconazole. Clin Chem Lab Med 2010; 48:1723-31
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
The Evolution of Sociality and the Polyvagal Theory
The polyvagal theory (PT), offered by Porges (2021), proposes that the
autonomic nervous system (ANS) was repurposed in mammals, via a second vagal
nerve, to suppress defensive strategies and support the expression of
sociality. Three critical assumptions of this theory are that (1) the
transition of the ANS was associated with the evolution of social mammals from
asocial reptiles; (2) the transition enabled mammals, unlike their reptilian
ancestors, to derive a biological benefit from social interactions; and (3) the
transition forces a less parsimonious explanation (convergence) for the
evolution of social behavior in birds and mammals, since birds evolved from a
reptilian lineage. Two recently published reviews, however, provided compelling
evidence that the social asocial dichotomy is overly simplistic, neglects the
diversity of vertebrate social systems, impedes our understanding of the
evolution of social behavior, and perpetuates the erroneous belief that one
group, non-avian reptiles, is incapable of complex social behavior. In the
worst case, if PT depends upon a transition from asocial reptiles to social
mammals, then the ability of PT to explain the evolution of the mammalian ANS
is highly questionable. A great number of social behaviors occur in both
reptiles and mammals. In the best case, PT has misused the terms social and
asocial. Even here, however, the theory would still need to identify a
particular suite of behaviors found in mammals and not reptiles that could be
associated with, or explain, the transition of the ANS, and then replace the
asocial and social labels with more specific descriptors.Comment: 15 pages, 1 figur
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