33,930 research outputs found
Latin transversals of rectangular arrays
Let m and n be integers, . An m by n array consists of mn
cells, arranged in m rows and n columns, and each cell contains exactly one
symbol. A transversal of an array consists of m cells, one from each row and no
two from the same column. A latin transversal is a transversal in which no
symbol appears more than once. We will establish a sufficient condition that a
3 by n array has a latin transversal.Comment: Theorem 4 has been added, which provides a lower bound on L(m,n
Non-Linear Heart Rate Variability and Risk Stratification in Cardiovascular Disease
Traditional time and frequency domain heart rate variability (HRV) have cardiac patients at risk of mortality post-myocardial infarction. More recently, non linear HRV has been applied to risk stratification of cardiac patients. In this review we describe studies of non linear HRV and outcome in cardiac patients. We have included studies that used the three most common non-linear indices: power law slope, the short term fractal scaling exponent and measures based on Poincaré plots. We suggest that a combination of traditional and non-linear HRV may be optimal for risk stratification. Considerations in using non linear HRV in a clinical setting are described
The Impact of Monetary Policy on Bank Balance Sheets
This paper uses disaggregated data on bank balance sheets to provide a test of the lending view of monetary policy transmission. We argue that if the lending view is correct, one should expect the loan and security portfolios of large and small banks to respond differentially to a contraction in monetary policy. We first develop this point with a theoretical model; we then test to see if the model's predictions are borne out in the data.
OPTIMAL STEADY STATES AND THE EFFECTS OF DISCOUNTING
A simple expression for finding and characterizing the optimal steady state of a general dynamic optimization problem is derived. This expression is easy to interpret and easy to apply for various purposes as, for example, to analytically investigate the effect of the discount rate upon optimal steady state stock levels. It is shown that an increase in the discount rate may result in higher optimal stock levels even in the one-dimensional (single species) case in nonlinear models. An important result is that if demand is inelastic at the optimal steady state, a higher discount rate will unequivocally imply higher standing stock(s). Increasing marginal cost of harvest will further strengthen this result. In the multidimensional case it is demonstrated that an increased discount rate may result in higher optimal stock levels for all stocks included in the model.Research Methods/ Statistical Methods,
Housing and labor market distortions in Poland : linkages and policy implications
Poland's housing and macroeconomic policies have restricted investments in housing and urban infrastructure to a level well below that of other European countries. This has resulted in a shortage of housing typified by 15 to 20 year waits for government sponsored housing. Shortages of this magnitude are likely to cause distortions with impacts on patterns of savings and consumption, the price level, and on the functioning of labor markets. This paper focuses particularly on how housing market distortions are transmitted to labor markets, with impacts on rates of migration, relative wage levels among different regions, and, by implication, on the productivity of the Polish work force. The basic thesis of the paper is that if housing markets are prevented from reaching their competitive equilibrium that labor markets will similarly be prevented. Evidence is examined on the extent of housing and labor market disequilibria, and estimates econometric models that relate internal migration and relative wages to alternative measures of housing market disequilibria. From these analyses it is concluded that labor markets are in fact distorted by housing market distortions, with potentially major macroeconomic costs.Banks&Banking Reform,Municipal Financial Management,Housing&Human Habitats,Public Sector Economics&Finance,Urban Housing
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Landscape context mediates the relationship between plant functional traits and decomposition
Aims: It has been well demonstrated that several interacting endogenous and exogenous factors influence decomposition. However, teasing apart the direct and indirect effects of these factors to predict decomposition patterns in heterogenous landscapes remains a key challenge. Methods: At 157 locations in a temperate forest, we measured decomposition of a standard substrate (filter paper) over two years, the landscape context in which decomposition took place, and the functional composition of the woody species that contributed leaf litter to the forest floor where litter bags were placed. We tested for direct and indirect effects of landscape context and direct effects of forest functional composition on decay using structural equation modelling. Results: We found that landscape context had direct effects on decay and indirect effects on decay via its influence on the functional composition of the surrounding forest. Forest functional composition also had direct effects on decay, but these effects decreased or disappeared completely over time. Moreover, community weighted mean trait values were better predictors of decay than functional dispersion of leaf traits, and leaf nitrogen content and carbon content were better predictors of decay than leaf dry matter content or leaf toughness. Conclusions: Our results highlight the importance of an integrative approach that examines the direct and indirect effects of multiple factors for understanding and predicting decomposition patterns across heterogenous landscapes
Magnetic correlations of the quasi-one-dimensional half-integer spin-chain antiferromagnets SrVO ( = Co, Mn)
Magnetic correlations of two iso-structural quasi-one-dimensional (1D)
antiferromagnetic spin-chain compounds SrVO ( = Co, Mn) have
been investigated by magnetization and powder neutron diffraction. Two
different collinear antiferromagnetic (AFM) structures, characterized by the
propagation vectors, = (0 0 1) and = (0 0 0), have been found below
5.2 K and 42.2 K for the Co- and Mn-compounds, respectively. For
the Mn-compound, AFM chains (along the axis) order ferromagnetically within
the plane, whereas, for the Co-compound, AFM chains order
ferro-/antiferromagnetically along the direction. The critical exponent
study confirms that the Co- and Mn-compounds belong to the Ising and Heisenberg
universality classes, respectively. For both compounds, short-range spin-spin
correlations are present over a wide temperature range above . The reduced
ordered moments at base temperature (1.5 K) indicate the presence of quantum
fluctuations in both compounds due to the quasi-1D magnetic interactions.Comment: 14 pages, 10 figures, 9 table
Nodular Sarcoidosis Masquerading as Cancer.
Nodular lung disease is a rare pulmonary manifestation of sarcoidosis and resembles metastatic neoplasm disease. Nodular sarcoidosis is rare, varying from 1.6% to 4% of patients with sarcoidosis. Radiographic nodules measure from 1 to 5 cm in diameter that typically consist of coalescent granulomas. There is limited data on this form of sarcoidosis and its presentation can mimic primary or metastatic pulmonary neoplasms. Nodular sarcoidosis has a favorable prognosis, and resolution can be seen with oral corticosteroids. Herein, we present such a case of nodular pulmonary sarcoidosis with a lung nodule measured up to 6 cm
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