482 research outputs found
Information homeostasis as a fundamental principle governing the cell division and death
To express genetic information with minimal error is one of the key functions of a cell. Here we propose an information theory based phenomenological model for the expression of genetic information. Based on the model we propose, the concept of "information homeostasis" ensures that genetic information is expressed with minimal error. We suggest that together with energy homeostasis, information homeostasis is a fundamental working principle of a biological cell. This model proposes a novel explanation of why a cell divides and why it stops to divide and thus provides novel insight into oncogenesis and various neuro-degenerative diseases. Moreover, the model suggests a theoretical framework to understand cell division and death, beyond specific biochemical pathways
Some new evidence on determinants of foreign direct investment in developing countries
The authors of this paper expand on earlier studies of the determinants of foreign direct investment (FDI) by empirically analyzing various factors - including political risk, business conditions, and macroeconomic variables - that influence direct investment flows to developing countries. They try to fill a gap in the literature by examining qualitative factors. Using a pooled model of developing countries, they test three groups of hypotheses on what influences direct investment. Tests of the first hypothesis indicate that a qualitative index of political risk is a significant determinant of FDI flows for countries that have historically attracted high FDI flows. For countries that have not attracted such flows, sociopolitical instability has a negative impact on investment flows. Tests of the second hypothesis show that a general qualitative index of business operation conditions is an important determinant of FDI in countries that receive high flows. This country group also shows a positive relationship between taxes on international transactions and FDI flows. Results from tests of the third hypothesis reveal that exports generally, especially manufacturing exports, are significant determinant of FDI flows for countries in which FDI is high. Finally, export orientation is the strongest variable for explaining why a country attracts FDI. This finding is in line with the secular trend toward increasing complementarity between trade and FDI.Labor Policies,Economic Theory&Research,Environmental Economics&Policies,Statistical&Mathematical Sciences,International Terrorism&Counterterrorism,Environmental Economics&Policies,Inequality,Statistical&Mathematical Sciences,Foreign Direct Investment,Economic Theory&Research
Synthesis of 2,2',4,4',6,6' Hexanitrostilbene
An economical method of synthesis of HNS has been developed in which solution of TNT is treated with 6 per cent sodium hypochlorite at 3 +-1 degree Celsius to get the desired product. Effect of concentration as well as pH of sodium hypochlorite on the yield of HNS has also been studied. The solubility of HNS in various organic solvents has also been determined
New atmospheric parameters and spectral interpolator for the MILES cool stars
Context: The full spectrum fitting of stellar spectra against a library of
empirical spectra is a well-established approach to measure the atmospheric
parameters of FGK stars with a high internal consistency. Extending it towards
cooler stars still remains a challenge. Aims: We address this question by
improving the interpolator of the MILES (Medium-resolution INT Library of
Empirical Spectra) library in the low effective temperature regime (Tefff <
4800 K), and we refine the determination of the parameters of the cool MILES
stars. Methods: We use the ULySS package to determine the atmospheric
parameters (Teff, logg and [Fe/H]), and measure the biases of the results with
respect to our updated compilation of parameters calibrated against theoretical
spectra. After correcting some systematic effects, we compute a new
interpolator that we finally use to redetermine the atmospheric parameters
homogeneously and assess the biases. Results: Based on an updated literature
compilation, we determine Teff in a more accurate and unbiased manner compared
to those determined with the original interpolator. The validity range is
extended downwards to about Teff = 2900 K compared to 3500 K previously. The
mean residual biases on Teff, logg, and [Fe/H], with respect to the literature
compilation for the coolest stars (Teff <= 3800 K) computed using the new
interpolator, are -15 K, -0.02 dex, and 0.02 dex respectively. The
corresponding estimations of the external precision are 63 K, 0.23 dex, and
0.15 dex respectively. For the stars with Teff in the range 3800 - 4200 K, the
determinations of Teff and [Fe/H] have been slightly improved. At higher
temperatures, the new interpolator is comparable to the original one. The new
version of the interpolator is publicly available.Comment: A&A Accepted, 30 pages, 10 figure
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