4,688 research outputs found
Kinetic behavior of the general modifier mechanism of Botts and Morales with non-equilibrium binding
In this paper, we perform a complete analysis of the kinetic behavior of the
general modifier mechanism of Botts and Morales in both equilibrium steady
states and non-equilibrium steady states (NESS). Enlightened by the
non-equilibrium theory of Markov chains, we introduce the net flux into
discussion and acquire an expression of product rate in NESS, which has clear
biophysical significance. Up till now, it is a general belief that being an
activator or an inhibitor is an intrinsic property of the modifier. However, we
reveal that this traditional point of view is based on the equilibrium
assumption. A modifier may no longer be an overall activator or inhibitor when
the reaction system is not in equilibrium. Based on the regulation of enzyme
activity by the modifier concentration, we classify the kinetic behavior of the
modifier into three categories, which are named hyperbolic behavior,
bell-shaped behavior, and switching behavior, respectively. We show that the
switching phenomenon, in which a modifier may convert between an activator and
an inhibitor when the modifier concentration varies, occurs only in NESS.
Effects of drugs on the Pgp ATPase activity, where drugs may convert from
activators to inhibitors with the increase of the drug concentration, are taken
as a typical example to demonstrate the occurrence of the switching phenomenon.Comment: 19 pages, 10 figure
Multi-wavelength Stellar Polarimetry of the Filamentary Cloud IC5146: I. Dust Properties
We present optical and near-infrared stellar polarization observations toward
the dark filamentary clouds associated with IC5146. The data allow us to
investigate the dust properties (this paper) and the magnetic field structure
(Paper II). A total of 2022 background stars were detected in -, -,
-, and/or -bands to mag. The ratio of the polarization
percentage at different wavelengths provides an estimate of ,
the wavelength of peak polarization, which is an indicator of the small-size
cutoff of the grain size distribution. The grain size distribution seems to
significantly change at 3 mag, where both the average and dispersion
of decrease. In addition, we found
0.6-0.9 m for mag, which is larger than the 0.55 m
in the general ISM, suggesting that grain growth has already started in low
regions. Our data also reveal that polarization efficiency (PE ) decreases with as a power-law in -, -, and
-bands with indices of -0.710.10, -1.230.10 and -0.530.09.
However, -band data show a power index change; the PE varies with
steeply (index of -0.950.30) when mag but softly
(index of -0.250.06) for greater values. The soft decay of PE in
high regions is consistent with the Radiative Aligned Torque model,
suggesting that our data trace the magnetic field to mag.
Furthermore, the breakpoint found in -band is similar to the where we
found the dispersion significantly decreased. Therefore, the
flat PE- in high regions implies that the power index changes result
from additional grain growth.Comment: 31 pages, 17 figures, and 3 tables; accepted for publication in Ap
Raman Characterizations of Red Blood Cells With β-Thalassemia Using Laser Tweezers Raman Spectroscopy
This study aimed to study the differences in Raman spectra of red blood cells (RBCs) among patients with β-thalassemia and controls using laser tweezers Raman spectroscopy (LTRS) system.A total of 33 patients with β-thalassemia major, 49 with β-thalassemia minor, and 65 controls were studied. Raman spectra of RBCs for each sample were recorded. Principal component analysis (PCA), one-way analysis of variance (ANOVA), and independent-sample t test were performed.The intensities of Raman spectra of β-thalassemia (major and minor) RBCs were lower than those of controls, especially at bands 1546, 1603, and 1619 cm. The intensity ratio of band 1546 cm to band 1448 cm demonstrated that there was a significant difference between the spectra of β-thalassemia major (mostly below 2.15) and those of controls. The spectra of controls could be well distinguished from those of β-thalassemia major using PCA. After normalization, the spectra of two different genotypes with β/β mutations mainly overlapped, while those with β/β mutations had lower intensity at bands 1546, 1603, and 1619 cm.The present study provided Raman characteristics of RBCs in patients with β-thalassemia major and supported the use of LTRS as a method for screening β-thalassemia major. The recognition rate for β-thalassemia minor needs to be further improved
The Nonlinear Permittivity Including Non-Abelian Self-interaction of Plasmons in Quark-Gluon Plasma
By decomposing the distribution functions and color field to regular and
fluctuation parts, the solution of the semi-classical kinetic equations of
quark-gluon plasma is analyzed. Through expanding the kinetic equations of the
fluctuation parts to third order, the nonlinear permittivity including the
self-interaction of gauge field is obtained and a rough numerical estimate is
given out for the important \vk =0 modes of the pure gluon plasma.Comment: 7 pages, shortened version accepted by Chin.Phys.Let
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